mae - 446 energy systems design project - nomad€¦ · nomad power is a design group consisting of...

Hybrid Emergency Microturbine Generator (HEMG)

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MAE - 446 ENERGY SYSTEMS DESIGN

PROJECT - NOMAD

Team Picture: (From Left) Shuyu Gong, Danyang Yu, Guoyi Li, Tanvi Nidgalkar,

Jake Gunnoe (back), Ben Sandoval, Tianze Peng

Hybrid Emergency Microturbine Generator (HEMG) System

Sponsor: Dr Steven Trimble, Professor of Practice

Date: 22nd, April, 2014


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Design Team NOMAD: Declaration of Responsibility

I hereby declare that I have contributed to and reviewed the contents of this final report and

take responsibility for the content herein.

_______________________ Date:

Benjamin Sandoval



_______________________ Date:

Tanvi Nidgalkar



_______________________ Date:

Tianze Peng



_______________________ Date:

Shuyu Gong



_______________________ Date:

Jake Gunnoe



_______________________ Date:

Danyang Yu



_______________________ Date:

Guoyi Li


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Executive Summary

The following report is a documentation of the steps and processes followed in completing the capstone

project for Ira A. Fulton School of Engineering Mechanical Engineering

undergraduate program. The details are presented to meet the Accreditation Board for

Engineering and Technology criteria that demonstrate the ability of the team to function as an effective

team of engineers in a simulated professional setting.

Steven Trimble, Professor of Practice acted as the primary advisor of the project. Randy Roberson,

Disaster Relief Expert, acted as the customer for the Nomad design team. He challenged the team with a

unique problem that necessitates an energy system design solution. The problem in short: When response

teams first arrive to a disaster zone, they have no access to power and must use small portable generators

and solar panels to charge their computers, communications, and telemedicine equipment. As their relief

camp grows in size the demand for power also grows. Within one week of the disaster, 20x8x8ft

“containerized” facilities are continuously shipped in, further increasing the power demand. Demand

levels reach peaks during hot days when air conditioning and dehumidification is required for the

containerized surgery rooms. He requires a portable energy system that can supply high quality power to

a growing demand for an extended period of time. The system must require minimal maintenance.

Furthermore, the energy system fit in a 20x8x8ft shipping container and be capable of delivery via a

Sikorsky S-64 SkyCrane Helicopter.

Randy Roberson’s aforementioned needs served as the requirements of the energy system that we have

come to know as the “Hybrid Emergency MicroTurbine Generator” (HEMG). His needs also helped the

team establish a mission profile for optimizing a hybrid system that utilizes an onboard battery in

conjunction with the microturbines. Upon further research and planning, the team was able to define the

scope of the project and begin conceptualization.

The final preliminary design of this energy system is unique. It is completely self contained and can be set

down nearly anywhere via a helicopter. The system is capable of delivering 95kW, of which 10kW is

high quality, uninterrupted power. It can run at this maximum output for roughly 5.7 days continuously,

assuming standard day conditions. During periods of low demand, a ‘hybrid mode’ enables the system to

efficiently output power over the complete range of 0 to 95 KW, a feat not possible with microturbines

alone. That being said, the system can operate on the mission profile (a ramped demand) for over 1000

hrs.

Team Nomad strictly adhered to the Integrated Product Development Support (IPDS) process in order to

minimize the amount of rework necessary in later stages, thereby reducing the time used in development,

allowing for efficient team dynamics. Obstacles and the processes taken to overcome them are explained

in full detail within the relevant sections of the report.

For the established requirements and mission profile, this system is the optimal configuration; however,

with further development and weight optimization, the runtime of the system might be capable of

increase. Overall, team Nomad believes that the Hybrid Emergency Microturbine Generator preliminary


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design was a success and would like to continue development into the detailed design phase. Below is a

conceptual 3D rendering of the final preliminary design. The exterior walls of the shipping container have

been removed for component visibility.

Figure E1. An annotated 3D rendering of the preliminary design of the Hybrid Emergency Microturbine

Generator.


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Contents

Design Team NOMAD: Declaration of Responsibility ................................................................................ 2

1. Introduction ............................................................................................................................................. 10

1.1 Voice Of Customer/Background ....................................................................................................... 10

1.2 The Design Team .............................................................................................................................. 10

1.3 Design Need ..................................................................................................................................... 11

1.3.1 Natural Disaster Relief ............................................................................................................... 11

1.3.2 Provide Backup Grid Integrity ................................................................................................... 11

1.4 Problem Statement ........................................................................................................................... 13

1.4.1 Hypothetical Mission Profile and Resulting Need for a ‘Hybrid Mode’ ................................... 13

1.4.2 Design Space Limitation ............................................................................................................ 14

1.5 Physics Involved ........................................................................................................................... 15

1.6 Project Scope and Limitations .......................................................................................................... 16

1.7 Social Impact .................................................................................................................................... 16

1.7.1 Disaster Relief ............................................................................................................................ 16

1.7.2 Supplemental Energy Production ............................................................................................... 16

1.8 ABET Criteria/Final Report Cross Reference Table ........................................................................ 17

1.9 Report Organization .......................................................................................................................... 18

1.10 Project Notebook ............................................................................................................................ 18

2. Final Preliminary Design Description ..................................................................................................... 19

2.1 Design Description Overview ....................................................................................................... 19

2.1.1 Microturbine Generator Set Description .................................................................................... 21

2.1.2 Battery System Description ....................................................................................................... 22

2.1.3 Fuel System Description ............................................................................................................ 23

2.1.4 Safety System Description ......................................................................................................... 24

2.1.5 Packaging Description ............................................................................................................... 25

2.2 Method of Operation ......................................................................................................................... 26

2.3 Key Features and Benefits ................................................................................................................ 28

2.4 Key Performance Results .................................................................................................................. 29

2.5 Cost, Weight, and Runtime Results .................................................................................................. 31

2.6 Requirements/Validation Matrix ....................................................................................................... 32

2.7 Intellectual Property Considerations ................................................................................................. 34

3. Design Process and Project Planning ...................................................................................................... 35


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3.1 Integrated Product Design and Support (IPDS) Process ................................................................... 35

3.2 Project Plan ....................................................................................................................................... 36

3.2.1 Overview .................................................................................................................................... 36

3.2.2 Pre-Concept Design ................................................................................................................... 36

3.2.3. Key Issues ................................................................................................................................. 38

3.2.4. Technical Approach .................................................................................................................. 39

3.2.5. Project Management Approach ................................................................................................. 39

3.2.6 Risk Management ...................................................................................................................... 40

3.2.7 Work Breakdown Structure ....................................................................................................... 41

3.2.8 Project Schedule ......................................................................................................................... 42

3.2.9 Labor Loading and Labor Budget .............................................................................................. 43

3.2.10 Monetary Budget...................................................................................................................... 44

3.2.11 Project Success Factors ............................................................................................................ 44

4. Requirements and Constraints ............................................................................................................... 46

4.1 Needs to Requirements .................................................................................................................... 46

4.2 Applicable Standards and Regulations ............................................................................................ 50

4.3 Validation Methods .......................................................................................................................... 52

4.3.1 Analysis ...................................................................................................................................... 52

4.3.2 Solid Modelling ........................................................................................................................ 52

4.3.3 Research .................................................................................................................................... 52

4.4 Requirements/Validation Matrix .................................................................................................. 53

5. Conceptual Design .................................................................................................................................. 54

5.1 Functional Block Diagram ................................................................................................................ 54

5.2 Research of Prior Art ..................................................................................................................... 54

5.3. Conceptual Design Options .......................................................................................................... 55

5.3.1.Power Generation ....................................................................................................................... 55

5.3.2 Fuel Storage ............................................................................................................................... 56

5.3.3 Battery Function ......................................................................................................................... 56

5.5.4 System Packaging ...................................................................................................................... 56

5.4 Methods of Selecting Final Conceptual Design ................................................................................ 56

5.4.1 Power Generation Selection Criteria .......................................................................................... 56

5.5. Final Selection Comparisons and Rationale ................................................................................. 58

5.5.1 Power Generation ....................................................................................................................... 58


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5.5.2 Fuel Storage ............................................................................................................................... 58

5.5.3 Battery Function ......................................................................................................................... 58

5.5.4 System Packaging ...................................................................................................................... 59

5.6 Description of Final Conceptual Design ........................................................................................... 59

5.6.1 Microturbine Set Description ..................................................................................................... 59

5.6.2 Fuel Type/System Description ................................................................................................... 63

5.6.3 Battery System Description ....................................................................................................... 64

5.6.4 Safety System Description ......................................................................................................... 66

Summary of System Requirements ..................................................................................................... 66

System Specifications ......................................................................................................................... 66

5.6.5 Packaging Description ............................................................................................................... 66

5.7 Analysis............................................................................................................................................. 67

5.7.1 Gas Generator Selection and Rational ....................................................................................... 67

5.7.2 Battery System Selection and Rational ..................................................................................... 69

5.7.3 Fuel System Selection and Rational .......................................................................................... 70

5.7.4 Safety System Selection and Rational....................................................................................... 71

5.8 Proof of Concept Testing ................................................................................................................. 72

5.8.1 Test Plan .................................................................................................................................... 72

5.8.2 Mean Time Between Failure (MTBF) Testing and Prediction Models .................................... 72

5.8.3 Drop Testing ............................................................................................................................. 72

5.9 Cost of Electricity and Weight Model for Conceptual Design ................................................... 73

6 Preliminary Design and Optimization ..................................................................................................... 75

6.1 Final Configuration Block Diagram ................................................................................................ 75

6.2 Analysis Plan ................................................................................................................................... 75

6.3 Failure Modes and Effects Analysis ................................................................................................ 76

6.3.1 Thermodynamic Model ............................................................................................................. 77

6.4 System Optimization ........................................................................................................................ 79

6.5 Proof-of-Concept Testing ................................................................................................................ 80

6.6 Trade Studies ................................................................................................................................... 80

7. Project Performance ................................................................................................................................ 82

7.1. Project Metrics ................................................................................................................................. 82

7.2. Key Learnings .................................................................................................................................. 83

8. Project Conclusions ................................................................................................................................ 84


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9. Recommendations ................................................................................................................................... 84

References ................................................................................................................................................... 85

APPENDIX ................................................................................................................................................. 87

APPENDIX A - Microturbine Generator Specifications and Calculations ............................................ 87

APPENDIX B - Runtime Studies ........................................................................................................... 93

APPENDIX C - Fuel System Calculations ............................................................................................. 94

APPENDIX D - Other Battery System Specifications ........................................................................... 95

APPENDIX E - Safety System Calculation ............................................................................................ 97

APPENDIX F - Cost Model ................................................................................................................... 98

APPENDIX G - NOX emission analysis ................................................................................................. 99

APPENDIX H - Team members contact information ........................................................................... 100


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Figure # Description Page #

1.8.1 ABET Criteria/Final Report Cross Reference Table 16

2.5.1 Results of cost, weight, and runtime 30

2.6.1 Requirements Validation Matrix 31

3.2.1 Pre-Concept Design Critical Requirements 35

3.2.2 Design Risk 38

3.2.3 Project Risk 39

3.2.4 The projected labor loading hourse established at the beginning of the project 42



5.5.1 Categories, Weights, and Team Ratings (1-10) of Each Design Option 58

5.5.2 Comparison Scores of Each Option After Applying Weights 58

5.6.1 Performance Ratings at Full Load Power and ISO Conditions 60

5.6.2 Electrical Performance Ratings in Standalone Mode 61

5.6.3 Reference Cost from 2007 62

5.6.4 The Input Specifications 64

5.4.5 The Output Specifications 65

5.6.6 Sizing for Cylinder Options 66

5.6.7 Weight for Cylinder Options 66

5.7.1 Micro Turbine Trade Study 69

5.7.2 Trade Study: Battery System 70

5.7.3 Fuel System Trade Study 71

5.7.4 Trade Study : Safety System 72

5.9.1 COE and Weight Model 75

5.9.2 COE Model Factors 75

6.3.1 Top 5 FMEA Summary 78

6.2.1 Data reported in University of Colorado study 79

6.2.2 Temperatures reported in University of Colorado study 80


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1. Introduction

Nomad Power is a design group consisting of seven mechanical engineering students supported and

mentored by Stephen Trimble, Professor of Practice. The primary goal of Nomad Power is to design a

portable hybrid power system for disaster relief. To accomplish this, the design team has developed a

system using MicroTurbine technology. This report outlines the preliminary design, why the Hybrid

Emergency MicroTurbine Generator is needed, and how the design team formulated the design solution,

including details of all models, trade studies, and rework that led to the design outcome.

1.1 Voice Of Customer/Background

Randy Roberson, Senior Disaster Response & Telemedicine Specialist, provided a detailed description of

the response necessary in a disaster relief situation. Originally, the design objective was to create an

emergency power system packaged to fit on a semi truck trailer. However, after further conversations

with Randy, it became clear that this system would have to be packaged in a container sized for

convenient transport due to the inherent inaccessibility that occurs during disaster situations. Disaster

relief operations often utilize shipping containers, and Roberson specified this as the preferred packaging.

This decision went into further examination during the preliminary design stage of the project (see

Section 6).

As an adviser for the project, Roberson was able to provide this, and other valuable insight on deployable

systems and what specifically that entails in his line of work. He made it clear to the group, that although

disaster relief is not a field in which people “enjoy” more business, but it is without a doubt a very

necessary service. Roberson was able to illustrate that disaster relief is a ever-growing industry and is

constantly seeking new technologies to improve relief response and efforts. When he was introduced to

the initial pre-concept design for the Emergency MicroTurbine Generator, Roberson expressed great

interest and need for such a product.

1.2 The Design Team

The founding ideals of the design team was maximizing expertise while minimizing micro-management.

In order to do this, technical lead positions were assigned to individuals who had the most experience or

greatest personal interest in the specific area. The team consisted of four technical leads, and three project

managers who focused on system integration, project planning, and coordination.Throughout the

duration of the project, the design team met on a weekly basis in order keep other members up-to-date on

component progress and enable for more seamless component integration towards the end of the design

process.


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1.3 Design Need

1.3.1 Natural Disaster Relief

The design inspiration for the Hybrid Emergency MicroTurbine Generator was for aiding emergency

relief camps during natural disasters. In many cases, the most crippling thing that occurs is the widespread

loss of power, often accompanied by a shortage of fuel due to inaccessibility and/or subsequent demand.

It is common practice by some organizations to install micro-turbines to run vital facilities such as

hospitals, databases, and police stations. However, these installations take precious time, and we feel that

we can deliver high quality and flexible power with no installation necessary.

These emergency microturbine generator sets could also prove useful in situations such as the ice storms

that occurred in the eastern united states in February 2014. The harsh winter left over 600,000 PECO

energy customers without electricity. Unfortunately many of these people used electricity for heating

purposes, forcing them to endure the harsh winter. Had they had access to systems such as these,

responsive relief to larger populations might have been possible.

1.3.2 Provide Backup Grid Integrity

There are also a number of situations in which this emergency generator set could be benificially utilized

besides just emergency and disaster relief. President Barack Obama has been working closely with the

EPA and individual states to establish even lower emission requirements on new and existing power

plants. The regulation mandates that all future plants can exhaust a maximum of 1,100 pounds of carbon

dioxide per megawatt-hour generated. An average US coal plant currently dumps over 1,700 pounds of

carbon dioxide into the atmosphere for every megawatt-hour of energy it produces. For many plants, the

upgrade costs will be very high, for those that use dirty fuels such as coal this cost might be too high and

they will be forced to close. Because most coal plants currently produce around 1,700 pounds of carbon

dioxide per megawatt-hour, there are numerous coal plants scheduled to retire by the end of 2014. Figure

1.3.1, below shows the scheduled retirements for 2014, notice that the majority of these plants use Coal.


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Figure 1.3.1 Utility Scale Power Generating Units Planned to Retire from January 2014 to December 2014. (U.S.

EIA, ‘Annual Electric Generator Report’ and ‘Monthly Update to the Annual Electric Generator Report.’)

Due to the constantly increasing demand for energy and the effective loss of generation capacity a number

of new installations are planned to come on-line in order to take over the power demand. These systems,

below in Figure 1.3.2, are primarily solar, wind, and natural gas power plants.

Figure 1.3.2. Power Generating Units Planned to Go Online from January 2014 to December 2014. (U.S. EIA

‘Annual Electric Generator Report’ and ‘Monthly Update to the Annual Electric Generator Report.’)


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During this transitional time, the grid may suffer from instability before new plants fully take on the

power demand. In the interim, the HEMG would be suitable for deployment near vital facilities, ensuring

they stay online and connected to high quality power.

1.4 Problem Statement

Design an ultra low maintenance, self sustaining energy system capable of fire without access to auxiliary

power or fuel. It must have a minimum of two gas generators capable of producing a combined output of

no less than 70kW (at -5F to 110F). It must be packaged to fit in a 20x8x8ft shipping container, weighing

no more than 20,000 lbs with appropriate safety accommodations included for rapid transport via

Skycrane helicopter and potentially adverse conditions. The system must be capable of delivering at least

5kW of medical-grade power. Component and configuration selection must be purposed to maximize the

runtime for the given hypothetical mission profile that simulates the power demand for a growing disaster

relief camp.

1.4.1 Hypothetical Mission Profile and Resulting Need for a ‘Hybrid Mode’

In a disaster situation, the power demand for a relief camp follows a growth model based on the amount

of resources and equipment onsite. During the early hours of relief, power demands are low, and grow

slowly as more supplies are delivered. Until the the roads are cleared and a significant supply chain is

established, the system will have to supply power to loads that are below the operating range of the

selected gas turbines. To this problem, two solutions exist: 1) Select a small generator capable of

producing power during low demand or 2) Select a battery system capable of raising the fuel conversion

efficiency during this time of low demand. Because of the constraints and requirements established early

on, the design team decided to select a battery system that was optimal for the given mission profile.

Figure 1.4.1. Hypothetical Mission profile for a growing disaster relief camp (supply chain established at 1100

hours, represented by quickened demand growth.)


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1.4.2 Design Space Limitation

The design space is limited primarily by the constraints defined by the shipping container and the

maximum lift of a medium-lift helicopter, specifically the Sikorsky S-64 SkyCrane. On one end of the

spectrum, a small generator would be light and thus leave room for a substantial amount of fuel. If said

generator is 1kW, it would be capable of running for hundreds of hours without refueling, however it

would not be capable of operating substantial facilities. If the generator is in the 200 kW range, not only

is it heavier, leaving less room/weight for fuel, but additionally the fuel consumption increases nearly 1:1

with the output. That being said, the runtime is primarily a function of power output and fuel capacity, as

summarized in the figure below.

Figure 1.4.2. A simple explanation of the size constraints and design space limited by the packaging and weight

requirements.


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1.5 Physics Involved

The operation of a microturbine is exactly the same as it’s larger counterpart, the gas turbine. First, is

compressed, raising the temperature and pressure. This system utilizes a recuperator to preheat the air

using waste heat from the exhaust gases before entering the combustion chamber. Heat is added to the air

by igniting fuel, raising the temperature and volume of the air for expansion through the turbine. The

turbine shaft produces usable work that drives the compressor and an electric generator. A diagram of the

microturbine generator utilized in this design is below in Figure 1.4.3.

Figure 1.4.3. A diagram denoting the operation of the microturbine utilized in this design.

The major drawback of a gas turbine heat engine is that it drastically drops in efficiency at high

temperatures or low demands. A delicate balance between battery size, weight, and resulting runtime

must be met in order to design the optimum disaster relief system.


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1.6 Project Scope and Limitations

This project is bounded from the ‘voice of customer’ to the ‘preliminary design’ phases of the integrated

product development and support system. Although this system might have some commercial

applications, due to the mission profile used for optimization, team nomad is focused on designing a

deployable power system for disaster relief.

1.7 Social Impact

The Hybrid Emergency MicroTurbine Generator has great potential for a variety of issues. Within the

bounds of its primary function of disaster relief alone it can fill an immense and dire societal need.

Looking further into the future the Hybrid Emergency MicroTurbine Generator could potentially pave the

way to a variety of different applications that require portable or quickly deployable power generation.

Thus the societal impact is two-fold: rapid disaster relief and accessible energy production.

1.7.1 Disaster Relief

Between 2011 and 2013, the US government spent $136 billion on disaster relief alone (Weiss, 2013).

When tragedy strikes the need for disaster relief is immense. This system is meant to support the first

responders throughout the initial stages of relief. By providing these individuals with the power they

need, they can continue to operate the equipment and facilities that are vital in establishing order in the

chaos.

1.7.2 Supplemental Energy Production

The world needs energy, and the easier it is to get it, the better. In certain circumstances users may need a

temporary and portable effective supply of energy. This, for instance, could be military operations,

hospitals, or during infrastructure changes. A package such as the Hybrid Emergency MicroTurbine

Generator will enable entire buildings to temporarily operate off the grid in the case of power outages and

other similar instances. Because the Hybrid Emergency MicroTurbine Generator can be quickly deployed,

its use requires short notice. A technology such as this could change how we respond to changes or

outages in general power infrastructure.


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1.8 ABET Criteria/Final Report Cross Reference Table

A note to the ABET Assessors,

This report has been specifically tailored to meet the accreditation requirements described in the ABET

criteria. It contains all material and calculations immediately relevant, however, we also have a network

storage system (through Google Drive) that enabled the efficient documentation, sharing, and syncing of

all documents, research, and other related media. This system ensured that every member had access to

the most up-to-date information at all times, provided an internet connection. Essentially, we effectively

utilized an electronic design notebook, which is described in more detail in the next section, 1.10. Table

1.8.1, located on the next page, outlines the ABET criteria and where each requirement is addressed in

the report.

Table.1.8.1 ABET Criteria/Final Report Cross Reference Table

SR

NO. OUTCOME

LEVEL OF

KNOWLEDGE

REPORT

REFERENCE

1 An ability to apply knowledge of mathematics, science,

and engineering Analysis Section 5,6

2

An ability to design and conduct experiments, as well as

analyze and interpret data Analysis Section 5,6

3

An ability to design a system, component or process to

meet desired needs within realistic constraints such as

economic, environmental, social, political, ethical, health

and safety, manufacturability, and sustainability

Analysis Seetion 2,4,

Appendices

4 An ability to identify, formulate, and solve engineering

problems Analysis Section 1,5,6

5 An understanding of professional and ethical

responsibility Application

Not

Applicable

6 An ability to communicate effectively Application Entire Report

7

The broad education necessary to understand the impact

of engineering solutions in a global, economic,

environmental, and societal context.

Comprehension Section 1

8 A recognition of the need for, and an ability to engage in

lifelong learning Application Research

9 A knowledge of contemporary issues Application Section 1

10 An ability to use the technique, skills, and modern

engineering tools necessary for engineering practice. Analysis

Section 5, 6,

Appendices

(Solidworks,

Matlab)


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1.9 Report Organization

The report is divided into eight sections. Section 1 discusses the societal need, the project

problem statement and project scope. Section 2 presents the final preliminary design that

has been optimized to meet the requirements and the hypothetical mission profile. Section 3 discusses the

project plan that was established early and followed throughout the preliminary design. Section 4 explains

how the design requirements were developed and 5 present the conceptual and preliminary design efforts,

respectively. Section 6 summarizes the project plan effectiveness in terms of schedule, labour budget,

material budget, meeting requirements and mitigating risks. Section 7 discusses the project conclusions

and section 8 provides go forward recommendations. The appendix is located a the end and contains

detailed information on trade studies not shown in the report and detailed component specifications.

1.10 Project Notebook

As previously mentioned, the team organized all documents in a shared folder on Google Drive. The

folder contains detailed descriptions of all the trade studies, analyses, tests and team discussions. The final

report is written as a comprehensive, stand-alone document with all relevant information either listed in

the body or the appendix. That being said, a copy of the Team Notebook file structure is available upon

request. Using this system has a number of benefits including: All files up to date, all changes are logged,

files become available as soon as they are created, and they can be edited and viewed from a mobile

Android or Iphone device. Additionally, no expensive software is needed to edit or view the majority of

the file formats. Figure 1.9.1, below, is a screen capture of the shared folder.

Figure 1.9.1. A screen capture of the shared Google Drive folder used for the organization of all project relevant

documents, logs, and information.


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2. Final Preliminary Design Description

This section describes the final design preliminary design tailored to meet Randy Roberson’s (advisor,

disaster relief and telemedicine specialist) needs and the requirements that resulted therefrom.

2.1 Design Description Overview

Team Nomad was successful in developing a system to meet the majority of the requirements and

constraints without prototype construction. Although there was a great deal of rework that occurred

throughout the design process, each iteration only improved the system in one form or another. The

spatially efficient packaging was a huge part of the design, and could only be completed after the

preliminary design components were selected. As shown in Figure 2.1.1 below, the team was successful

in selecting components and a configuration pattern that met the spatial constraints. Overall, the design

team is proud of the Hybrid Emergency MicroTurbine Generator and after finalizing the weight and fuel

calculations, it performs better than expected, capable of outputting 95kW for 5.7 days at a total weight of

20,000lbs.

Figure 2.1.1 A 3D rendering of the Hybrid Emergency MicroTurbine Generator system with major

components shown. The watertight exterior shell of the packaging shipping container is not shown.

The figure below (Figure 2.1.2) is a block diagram that represents the functional components of the

system that are shown Figure 2.1.1. The diagram is a simplified version of the Hybrid Emergency

MicroTurbine Generator system, included for the sake of clarity. As shown in the block diagram, the

65kW microturbine acts as the master while the 30kW microturbine acts as the slave.


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Figure 2.1.2. Preliminary Design component block diagram.


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2.1.1 Microturbine Generator Set Description

The first stage of our project was to devise the system heat engine. A comparative study using a decision

matrix was performed comparing Diesel Generators and Microturbines to determine the model that gives

optimal performance with respect to weight, size, and efficiency, all of which are directly related to the

system runtime. The design team determined that the Capstone C30 and Capstone C65 microturbines are

the optimum gas generators for the specified purpose and resulting constraints/requirements. In selecting

the best generator, it was necessary to determine a microturbine size capable of sharing the limited space

available while still providing an adequate amount of power. Spin up time is short, runtime is optimal,

maintenance is simple and infrequent. All other components are designed around the function, efficiency,

and safety of these gas generators.

Figure 2.1.3. 3D model with Capstone diagrams of the selected gas generator combination,

namely: the Capstone C30 and Capstone C65 microturbine generator set.

Certifications

● CARB 2010

● UL-2200 (UL files AU2687, E209370)

● ISO 9001:2008

● ISO 14001:2004


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2.1.2 Battery System Description

The battery system selected for the preliminary design is an APC Symmetra 10 kW unit. This battery

system enables the plant to run at very low loads without operating the turbine at part power, thus saving

fuel and maximizing turbine efficiency. Furthermore, the battery will support higher-than-normal load

demands. The battery system will be paired with a controller that allows users to specify overall function

and output times of the battery system. This will allow users to determine if they would prefer an

emergency high-load support system, or a supplementary energy output system. The controller would also

allow users to determine at what capacity the battery would begin charging/discharging.

Figure 2.1.4. 3D Model of the APC battery system.

Certifications

● cUL Listed

● CE Mark

● CSA C22.2 No.107.3-05

● EN 50091-1, 2, 3

● ENERGY STAR (USA)

● Eurobat General Purpose

● FCC Part 15 Class A

● ISO 14001, 9001

● UL 1778, 60950


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2.1.3 Fuel System Description

In the conceptual design phase, the system utilized a high pressure spherical tank to house compressed

natural gas. After further analysis during the preliminary design phase, it was determined that a liquid fuel

would provide drastic increases in runtime due to the inherent energy density and the ability to store the

fuel in a significantly lighter vessel. For the fuel storage vessel, the design team selected a rubberized

nylon fuel bladder manufactured by Aero Tec Laboratories and similar to those used by the military or in

ultralight aircraft. The bladder is capable of holding 3140 gallons of JP-8 fuel, although it’s maximum

capacity for airlift via Skycrane is roughly 9,700lbs of liquid fuel.

Figure 2.1.5. 3D Model of the fuel bladder and fuel line.

Certifications

● ATL-9000 (Manufacturer Quality Control)

● Mil-Q-9858-A

● Mil-I-45208

● ISO-9001-2008


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2.1.4 Safety System Description

The safety system is more accurately described as a fire suppression system. It will be subcontracted to

Sensors located around the microturbines sense for a ‘flash,’ usually signifying the ignition of fuel outside

of the combustion chamber. At this point, the system would flood the entire volume with Carbon Dioxide

to quench any flames. A firewall and heat shield is placed between the generator set and the microturbines

to ensure that the fuel does not come into contact with high temperatures or flames (if they should erupt.)

Figure 2.1.6. 3D Model of the safety system with CO2 tank.

Certifications:

● ISO 9001

● ISO 14001

● Various NFPA


25

2.1.5 Packaging Description

In the preliminary phase, the design team began making necessary modifications, trades, and

optimizations to increase the runtime, which is primarily a function of output and fuel. When reviewing

the components of the system, it was clear that the shipping container was one of the heaviest components

(roughly 5,000lbs) and it was decided that modifications must be made. Figure 2.1.7 and 2.1.8, below

show the aluminum shipping container designed by the team. This container utilizes Aluminum

components as well as an internal framing that increases strength while reducing the thickness required of

the external panels. Note: The figure below does not show the inlet and exhaust ports that would be

necessary to accommodate the microturbine operation.

Figure 2.1.7. 3D Model of the 20x8x8ft ultralight aluminum shipping container.

Figure 2.1.8. 3D Model of the 20x8x8ft ultralight aluminum shipping container with system logo

Certifications:

Any international transport must have a valid safety approval plate or "CSC plate". CSC is the

abbreviation for Container Safety Convention.


26

2.2 Method of Operation

The mode of operation for the system has been optimized to operate at the highest efficiencies possible

through the utilization of two microturbine generators (30 and 65 kW) and a 10 kW battery system.

During periods of low demand, the battery will operate in conjunction with the 65 kW microturbine to

achieve efficiencies of greater than 25%, which is much higher than the efficiency of the 30 kW

microturbine operating at partial loads. Figure 2.2.1, below, summarizes the microturbine operation based

on the demand.

Figure 2.2.1. Showing the mode of operation through the entire range of expected power demands.

The battery system accomplishes two things: first it allows the system to operate at maximize efficiency

for low levels of demand and, second, it allows for more control of the power supply. Both of these goals

save fuel.

The systems will be stored in warehouses until the necessity warrants deployment. Systems will likely be

shipped via airplane and then dropped in the necessary location via medium lift helicopter. A visual

representation of deployment via helicopter is shown below in Figure 2.2.2.


27

Figure 2.2.2. Deployment of the Hybrid Emergency Microturbine Generator via Helicopter.

Figure 2.2.3. Depicting the removal of a defective 65kW microturbine using a forklift for servicing offsite.

Airdrop capabilities enable the system to be delivered to nearly any location no matter the circumstances.

This was a necessary requirement for the system from the early stages of development based on the nature

of natural disasters. In most cases, ground delivery is nearly impossible due to road blockage and access


28

to the necessary equipment. Delivering the system with a helicopter overcomes most of the deployment

challenges inherent of groundlocked systems.

When packaging the system, a great deal of consideration was given to the maintenance of the

microturbine generator sets. They are located directly inside one set of doors for easy access,

maintenance, and/or removal. A visual representation/explanation of this is located above in Figure 2.2.3.

2.3 Key Features and Benefits

This energy system has a number of features and benefits that make it suitable for use in emergency

situations. The most notable of these are listed below.

● Airdrop via Skycrane medium lift helicopter (Total weight: 20,000lbs)

○ Capable of operating for 5.8 days at 95kW on a partially full fuel tank (included in

weight)

○ Capable of operating for 77.2 days at 10kW through hybrid mode utilization

● Airdrop via Mi-26 , or other heavy lift helicopter (Total weight: 31,000lbs)

○ Capable of operating for 12.7 days at 95kW on a full fuel tank (included in weight)

○ Capable of operating for 167 days at 10kW through hybrid mode utilization

● Completely self sustaining capable of fire with no external fuel or power

● Low maintenance, long life expectancy (10 year runtime with regular maintenance.)

● Long shelf life due to the water/air tight shipping container

● Designed for rapid deployment

● Aluminum exterior packaging is light, water tight, rust proof, and extremely durable

● Empty weight is 10,218 lbs

● Fuel bladder capable of holding over 21,000lbs of JP-8 fuel

● Hybrid operation effectively increases the efficiency through the entire range of power outputs (0

-95kW)


29

2.4 Key Performance Results

The Capstone Microturbines have a partial power curve that is similar to those of other gas turbine

generators. At below 30% part power, the efficiency begins to reduce drastically, as shown in Figure

2.4.1, below.

Figure 2.4.1. Capstone C30 Microturbine efficiency curve at partial loads (Nasimento, 2013)

To offset this major loss in efficiency, the system operates in a hybrid mode with the 10 kW battery

supplying to all demands of less than 10 kW. The increase in efficiency of the demand range from

0 - 10 kW is drastic (up to 23% increases vs the microturbine alone), effectively increasing the system

runtime for the hypothetical mission profile. The efficiencies over the operable range are shown in Figure

2.4.2 below.

Figure 2.4.2. The top Graph is the efficiency curve of the baseline system with no battery (shown in blue) and the

optimized system with the 10 kW battery is shown in red. The lower graph is a ramped function of the demand over

the operable range.

In order to successfully deploy this system, it is necessary to predict the operating characteristics over a

range of temperatures and outputs. From this analysis, runtime and other useful information can be


30

gauged onsite. The figure below is a characterization of the performance of the system over various

temperatures and resulting outputs and efficiencies.

Figure 2.4.3. A characterization of the System while operating at various temperatures.


31

2.5 Cost, Weight, and Runtime Results

Below in Table 2.5.1 the total cost of the components, miscellaneous items, and the estimated cost of

manufacturing are summarized and totalled. Additionally, a column totalling the weight is included in this

model because the focus of the design was to optimize weight and subsequently increase the fuel

capacity and runtime.

Table 2.5.1 Results of cost, weight, and runtime

Component/System 2014 Cost

(US Dollars)

Weight

Capstone C30 $47,230 1,271 + 100 lbs

Capstone C65 $101,570 2,471 + 150 lbs

APC UPC $43,088 1,717 + 40 lbs

Rubberized Nylon Fuel Bladder, Aero Tech

Labor.

$2,000 4 + 1 lbs

Janus Fire Suppression $2,500 705 + 25 lbs

Ultralight Aluminum Shipping Container $10,000 3,000 + 400 lbs

Communications and Monitoring Eq. $4,000 50 + 10 lbs

Miscellaneous Items:

-Additional Structural Members

-Fuel Lines

-Insulation, Ducting, Filtration, Baffles

-Electrical Equipment, Wiring,

-Circuit Breakers

$30,000 1,000 + 200 lbs

Estimated Cost of Manufacturing $140,000

Total 2014$: $380,388 10,218 + 926 lbs

Total 2017$: $440,346 (5% infl.)

Remaining Weight for JP-8 Fuel: 9,782 + 926 lbs

(1, 460 gal)

Runtime at Full Power, Standard Day (95kW) 139 + 13.4 hrs

(5.8 days)

Runtime at 10 kW, Standard Day 1,215 + 193 hrs

(50 days)


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2.6 Requirements/Validation Matrix

A number of requirements and constraints were utilized to narrow the design space to the point where

preliminary designs could be conceptualized and developed in detail. Below in Table 2.6.1 and Table

2.6.2 the requirements are listed as well as the method of validation (how the design team confirmed that

the requirements were met by the preliminary design), the result of the validation, and finally the page

number where the requirement is validated.

Table 2.6.1 Requirements Validation Matrix

Requirement Method of

Validation

Validation Result

1) Full Power Efficiency > 24% Analysis Based on 5 test runs, full power

efficiency = 29.2+/- 0.5 %

2) 90kW Max Standard Day Analysis 95kW Max

3) 75kW @

-5 F > Temperature >120 F

Research Net Power Vs Temperature plots

for Capstone Microturbines

4) Operate for 3 days at 90kW Analysis Operates up to 5.8 days @

95kW

5) Operate for 720 hrs (30 days) on

Hypothetical Mission Profile

Analysis Mission profile operation

exceeds 1000hrs

6) 2 + Gas Turbines Analysis 2x Capstone MT, Power

Outputs: 30 KW + 65 KW, 95

KW Combined power O/P

7) Battery System Capable of

Hybrid Operation

Analysis/ Research 10 KW Battery with controller

8) 20,000lbs Max (With Fuel) Research, Solidworks Weight Requirement met

9) Packaged Size:

No more than 8x8x20ft

Research, Solidworks Size requirement met

10) Suspension System for

protecting microturbines from 1ft

corner, edge, flat drop

Subcontract Subcontract suspension system

to Lord Corporation motion

management technology

11) Fire suppression system capable

of clearing container volume 3

times

Analysis, Subcontract Volumetric Analysis of CO2,

system detailed design would be

subcontracted to KEVTA

Table continued on next page (Table 2.6.2)


33



Validation

Validation Result

12) Full Power Efficiency >

24%

Analysis Based on 5 test runs, full power efficiency =

29.2+/- 0.5 %

13) Push button start capability

for spin up of under 2 minutes

Research, Build, Test Preliminary designs indicate this is possible, but

the development of a prototype would be

necessary

14) Meet all Applicable

Standards and Regulations

(Described in Section 4.3)

Research, Build,

Certify

Research and historical examples indicate this is

possible, but a prototype would have to be

inspected for validation

15) CG located in the center of

the shipping container

Analysis, Solidworks NOT MET, CG is roughly 2 ft from the center of

the container

16) Operations Access Space

minimum of 3ft x 3ft

Analysis, Solidworks Access space is 4x3.5 ft

17) Aluminum structure

capable of supporting fully

loaded weight (30,000) with a

safety factor of n = 1.2

Analysis, FMEA,

Solidworks

Structure Capable of supporting 40,000lbs, n =

1.33

18) Fuel tank capable of

holding more than 3 days of

fuel at 95kW, roughly 5,000lbs.

Analysis Fuel tank capable of holding 21,200lbs

(The maximum weight for the system is set at

20,000lbs because of the payload limit of a

SkyCrane Helicopter. The tank is of larger

capacity in case a larger helicopter is used for

delivery. The increase in weight of the tank is

small and well worth the capacity and runtime

increase.)


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2.7 Intellectual Property Considerations

-

After a great deal of research, it was determined that there is nothing in this system that would prove

novel enough for a patent. Ultimately this system is a portable generator designed for the purpose of

disaster relief. That being said, there are a number of areas that might be noted as trade secrets. The most

apparent is the mode of operation and the utilization of a battery system to increase runtime during

periods of low demand. This mode of operation was numerically optimized, and it would definitely be

necessary to keep this operation out of the reach of competitors. The packaging of the system is also

unique and very effective, however reverse engineering would be simple and it cannot be considered a

trade secret.


35

3. Design Process and Project Planning

The design process is formatted to enable the team to work at optimal efficiency throughout the project

duration. The driving philosophy for the team is to work smarter not harder. To achieve this, the planning

and organization is based on team member capability and interest. The project schedule is modeled after

each team member’s availability, the milestones are projected in accordance to proposed team hours, and

the project goals fit personal team interests so as to provide an internal motivation for project progression.

3.1 Integrated Product Design and Support (IPDS) Process

The Integrated Product Development and Support (IPDS) process is a flowchart structure used to organize

project planning. The IPDS is a collection of basic project concepts and milestones that are essential to

any project, big or small. The diagram is shown below in Figure 3.1.1:

Figure 3.1.1 The IPDS Flow Chart

In this instance, the project is focused on conceptual design, not development or testing, so for our

purposes the IPDS process will be altered as shown in Figure 3.1.2:


36

Figure 3.1.2 The project-relevant portions of the IPDS process

3.2 Project Plan

3.2.1 Overview

The founding concept behind this project is dynamic energy generation and delivery. The team was

formed based on a mutual interest in this topic ensuring that each member has a personal stake in the

project advancement. Together, the team agreed upon a product concept, designed to provide energy in

emergency situations. Given this, the goal of project is to develop a seamless, portable, power plant that

can fit the needs of most disaster situations. The conclusion here is that whatever the final shape of the

project, the team must create a list of product metrics that any client could quickly understand in order to

determine whether or not the product was viable for their specific needs.

After an end goal was established, the project plan was based on working backwards by identifying each

step that would be needed to reach the overall goal. First by outlining the technical components of the

system, then by dividing the focus of each engineer to the technical areas, and finally, creating a list of

tasks that each system would require in order to meet the design needs.

3.2.2 Pre-Concept Design

It is first necessary to list out a few critical requirements before defining the pre-concept design. It is the

goal of the pre-concept design to act as a “starting point,” leaving space for changes and approaches that

the team is expecting to make as research is furthered and each individual system is designed in further

detail. Block diagrams of the initial-conceptual system are shown below in Figure 3.2.1 and 3.2.2.


37

Table 3.2.1: Pre-Concept Design Critical Requirements

Critical Requirement Numerical Metric

Must fit within a shipping container 20’x8’x8’ area

Maximum weight 20,000 lbs

High Demand Power Output 90 kW

Operation Time at Max Demand 2 days

Operation Time at Average Demand 11 days

Max On-Board Battery Demand 30 kW

No Auxiliary Fuel Requirement N/A

Max Drop Resistant Height 20’

Easy Disassembly for Maintenance Access N/A

On-Board Fire Suppression System N/A

Figures 3.2.1 and 3.2.2 below show the initial pre-concept design models.

Figure 3.2.1 A conceptual rendering with component systems labeled.


38

Figure 3.2.2 A functional block diagram, showing the interactions between the component systems

3.2.3. Key Issues

It is the goal of the team to locate areas where key issues will be present during the design process. This

insight was gained from thorough market research, topic-specific journals, and eventually guidance from

systems manufacturers.

The SWOT analysis for the project scope is detailed below.

Strengths:

1. Team members are experienced in thermodynamic analyses.

2. Team members are experienced in project project management and planning.

3. Team members are experienced in SolidWorks modeling.

4. Mentorship from Dr. Trimble, an industry-experienced professional.

5. Project concept is very unique and has never been developed.

Weaknesses:

1. Team members do not have direct industry experience.

2. Project has a high-demand time frame and team members have many time constraints.


39

3. Team members do not have a diverse engineering background.

Opportunities:

1. Consulting with Randy Roberson, an industry expert.

2. Innovative energy designs are in high demand.

Threats:

1. Microturbines are relatively new to the market and do not have high demand or availability.

2. Customers may prefer traditional methods of portable energy generation.

Following are the key issues that are needed to be addressed:

1. A major component/process that will be focused on will be ‘shopping’ i.e. searching for manufacturers

who make component systems that fall in line with our power-plant requirements;

2. Installation and maintenance manuals will be of particular importance once specific systems have been

selected.

3. The Runtime of the system will be optimized as much as possible, which would be a result of system

overall efficiency studies.

4. The optimization will need coming up with a mission profile against which optimization will be carried

out.

In the case of the pre-concept design, arbitrary systems (that have not yet been optimized) have been

selected to gain a further understanding of space, sizing, and layout requirements.

3.2.4. Technical Approach

The technical approach followed will be keeping in mind the sensitivity of the system. The components

that we chose will be chosen by undertaking a thorough trade study for choosing the system that fits our

system the best.

The results will be validated by modelling the system components by studying the weight, size and

system layout. This is one of the ways of achieving optimization relevant to the physical system.

The performance of the system is validated using softwares like Matlab. Since we are optimizing the

runtime we will be running matlab codes and plotting graphs to study and reach the best efficiency given

by the system.

3.2.5. Project Management Approach

The team project manager operates under the belief in alignment opposed to management. Meaning, that

it is better to identify individual strengths and capabilities instead of trying to control or manipulate any

team members to produce something beyond their means. To achieve this using a practical approach, each

team member creates his or her own project plan based on the same overview planning principles as the

project. In each overview plan, individuals will identify their


40

own personal investment in the project along with their availability. Using this as an initial step, the

project manager can then make a decision as to which tasks fit each member the best and what time

commitment to expect. In this way, team members are accountable to stay consistent to their own plan by

completing each of their outlined deliverables within their proposed time frame.

As the project progresses, each member is to track his or her own hours and report them to the PM. The

PM should be responsible for tracking total project hours and comparing it to the initial projection. Team

hours and metrics are to be posted on shared network drive so all members can see who is meeting their

requirements and who is falling short. Project metrics will include, meeting attendances, completed tasks,

and remaining tasks.

Throughout the project, decisions should be minimized where possible so as to avoid conflicting

viewpoints. If ever a split decision is to arise, the first step is to use a deductive approach to analyze why

the decision is needed and what relation it has to the project goals. If a consensus cannot be based on a

logic approach, then an expert will be consulted. A qualified expert should first be the team sponsor,

followed by any experience engineering professional.

3.2.6 Risk Management

The risk management has been separated into two key focuses: design risk and project risk. Design risk

deals primarily with risks that would be seen in the operation of the system, thus these risks needed to be

considered in order to ensure design quality. Project risk is risk that would occur in project management

or team collaboration. The identified risks and their mitigation methods are shown below.

Table 3.2.2 Design Risk

Risk Number Risk Description Possible Mitigation

1 Unpredictable variation in demand

load.

On-board battery system to augment

energy production for high and low

load demands.

2 High maintenance cost and complex

maintenance procedures.

Functional packaging design that

allows for easy component unpacking

for maintenance. Heave investigation

and testing of each product before

deployment.

3 Explosive chemical hazards. On-board fire suppression system in

case of failure.

4 Impact damage from deployment. On-board shock absorbing system.


41

Table 3.2.3 Project Risk

Risk Number Risk Description Possible Mitigation

1 Team member failing to meet project

demands.

Encourage each team member to set

their own goals and deliverables

relevant to the project to increase

accountability.

2 Lack of technical expertise. Frequent meetings with project

mentor to ensure technical accuracy.

3 Failure to meet time demands. Track weekly project hours and

compare to the projected schedule in

order to mitigate and deviations.

3.2.7 Work Breakdown Structure

The work breakdown structure below illustrates the different focuses and task that need to be addressed

through the duration of the project. Each focus is derived from a different stage established in the IPDS

diagram shown in Figure 3.2.3.

Figure 3.2.3 Project Work Breakdown Structure


42

3.2.8 Project Schedule

The project schedule below shows in which weeks the group plans on working on each individual section.

The figure reflects the categories defined in the work breakdown structure.

Figure 3.2.4 The projected project schedule


43

3.2.9 Labor Loading and Labor Budget

Table 3.2.4 below details the projected labor loading chart of the project. The project is divided into the

sections that were established in the work breakdown structure.

Table 3.2.4: The projected labor loading hourse established at the beginning of the project.

In Figure 3.2.5, the projected project hours are compared to the actual total hours spent working on the

project. Hours are shown versus the week number of the project.


44

Figure 3.2.5 The total projected work hours for the for project

3.2.10 Monetary Budget

This system will be unique from most other power systems because the COE will not be the center of

focus nor optimization. Portability and runtime will be what makes the system marketable, and these are

features that customers will (hopefully) find useful and pay the excess money for. Essentially, this system

is a portable, self-sustaining, backup generator and for qualitative budgetary estimates, will be rated

against backup diesel generator systems with similar capabilities. That being said, the definition and size

of the system budget will be a free variable that is to be determined through obtaining budgetary estimates

from manufacturers of appropriate component systems and using manufacturing and assembly cost

scaling-factors.

3.2.11 Project Success Factors

Summarizing the goal of this project: to create an adequate design within the projected time - an adequate

design will be one that presents a marketable product complete with operation performance specifications

and safety features. The major factors that will contribute to achieving this goal and ultimately

considering this project successful are as follows:

● Regular team and sub-group meetings

● Communication will be emphasized

● Project status will be monitored on a weekly basis

● Scheduled deliverables will be finished in detail, on time

● Individual team-member responsibility

● Individual team members have been charged with full component system designs

● Labor loading will be defined in detail and followed from the start to ensure

steady, quality work, avoiding a large, time intensive push as the project

approaches the submission deadline

● They must select, analyze, and define specifications for their system

● Specifications of systems must be communicated in detail

● Individual team members must be responsible for gaining relevant information

from system leaders of interacting component systems


45

● Proper market, topic research, shopping

● We will NOT try to ‘reinvent the wheel’

● High quality component systems from reliable manufacturers will be sought


46

4. Requirements and Constraints

This section provides an overview of how the requirements and constraints of the project were

determined. First the requirements were translated from voice of customer needs established in Section 1.

Then, the requirements were validated by using the industry standards are regulations.

4.1 Needs to Requirements

Originally, the design objective was to create an emergency power system packaged to fit on a semi truck

trailer, however, after further conversations with Roberson, Senior Disaster Response & Telemedicine

Specialist, it became clear that this system would have to be packaged in a container sized for convenient

transportation due to the inherent inaccessibility that occurs during disaster situations. Disaster relief

operations often utilize shipping containers.

Our target is developing a power system that helps sustain life in disaster zones. The system should be

able to supply power to disaster sites to operate vital facilities such as hospitals, databases, and police

stations. The system should be able to operate medical equipments with an uninterrupted power supply

for at least for 3 days continuously without refuelling.

Granted, although this is not a typical three-phase energy system present in residential American homes,

it will serve as a starting point to establish electrical infrastructure in damaged regions across the world.

Furthermore, the rotating turbine contains a vast amount of kinetic energy, the conversion between

different energy states will certainly create energy losses; therefore the group established an efficiency

requirement. Since designing a system with no energy loss is impossible, this requirement should ensure

that at least 95 kW can be sustained.


47

Table 4.1 Requirements Validation Matrix


Validation

Validation Result


efficiency = 29.2+/- 0.5 %


3) 75kW @





95kW




exceeds 1000hrs





Hybrid Operation



9) Packaged Size:











times




Table continued on next page (Table 4.1.1)


48



Validation

Validation Result

12) Full Power Efficiency >

24%

Analysis Based on 5 test runs, full power efficiency =

29.2+/- 0.5 %

13) Push button start capability

for spin up of under 2 minutes

Research, Build, Test Preliminary designs indicate this is possible, but

the development of a prototype would be

necessary

14) Meet all Applicable

Standards and Regulations

(Described in Section 4.3)

Research, Build,

Certify

Research and historical examples indicate this is

possible, but a prototype would have to be

inspected for validation

15) CG located in the center of

the shipping container

Analysis, Solidworks NOT MET, CG is roughly 2 ft from the center of

the container

16) Operations Access Space

minimum of 3ft x 3ft

Analysis, Solidworks Access space is 4x3.5 ft

17) Aluminum structure

capable of supporting fully

loaded weight (30,000) with a

safety factor of n = 1.2

Analysis, FMEA,

Solidworks

Structure Capable of supporting 40,000lbs, n =

1.33

18) Fuel tank capable of

holding more than 3 days of

fuel at 95kW, roughly 5,000lbs.

Analysis Fuel tank capable of holding 21,200lbs

(The maximum weight for the system is set at

20,000lbs because of the payload limit of a

SkyCrane Helicopter. The tank is of larger

capacity in case a larger helicopter is used for

delivery. The increase in weight of the tank is

small and well worth the capacity and runtime

increase.)

HEMG Full List of Requirements:

1) Total Package weight less than or equal to 20,000lbs

● The standard weight capacity of a helicopter which would be used to drop the packaged system

is maximum 20000 lbs.

2) Package Exterior Dimensions 19 x 7.6 x 7.6 ft

● This is because of the available packaging units having standard dimensions 20 X 8 X 8. Due to

clearance requirements for transportation, accessibility and heat dissipation requirements the

system is to be designed to a sized lesser than the one specified above.


49

3) Onboard High Pressure Fuel Tank

● The tank can supply the microturbine system with sufficient fuel due to the high pressure. In

addition, requirement of space has a relative strict limitation. To save space of entire system, high

pressure tank is necessary.

4) Battery System Capable of delivering 10 kWh

● Battery systems are designed to improve the dynamic load response capability of the system. And

greatly enhance the efficiency at low loads. However, the battery system should have efficient

float charging performance and low noise, withstand overload.

5) Fire suppression system that utilizes CO2, capable of filling the entire package volume

● In case of a system failure resulting in an on-board explosion or fire, this system will be use to

quickly douse and flames by filling the shipping container with CO2. The suppression system

should be compact in order to take up minimal space, but must still be able to adequately respond

to failure.

6) Compartmentalized, insulated, sound proofed MicroTurbine Generator chambers

● In order to minimize sound and fire hazards, the MTGs should be isolated in separate chambers

from the battery and fuel tank.

7) The energy system must have a simple installation and setup process

● The HEMG installation must only involve setting the system on the ground (or any other surface,

covered or uncovered) connecting loads, and powering up. To achieve this, the system must be

packaged in an operable state.

8) The owner of the installation must have the ability to do on-site and off-site maintenance and

monitoring

● The HEMG system must be connected to an on-board monitoring system that will allow the user

of to monitor all component functionality. In addition, a regular and scheduled maintenance plan

must be followed to ensure long life, high performance, and smooth operation.

● The packaging must allow the operator to remove and replace any malfunctioning components.

9) The system must have longevity and reliability

● This requires two gas generators for redundancy: a high and low output power generator for

achieving three speeds at which maximum efficiency can be achieved.

● This requires that the HEMG is thoroughly tested and a robust maintenance plan must be created

and adhered to.

10) The system must be capable of easy upgrades to meet market needs

● While the HEMG is currently designed to run on liquid fuel, the major advantage of MTGs is

their unique ability to nearly seamlessly switch between fuel types (sometimes with very little

modification other than the air fuel ratio and subsequent specific fuel consumption). This opens

up possibilities of overhauling in the future if a more cost effective liquid or gas fuel is

discovered or experiences a major reduction in price.

● Packaging auxiliary systems will make upgrades to the HEMG easy and cost effective

● Packaged Air Inlet Cooling System, increases efficiency in some climates


50

● Packaged Supplementary Fuel Tanks

● Packaged Water Heating and Delivery System, increasing efficiency by capturing waste heat.

This would effectively turn the MTGP into a Combined Heat and Power Plant (CHP)

● Packaged Organic Rankine Cycle

● Packaged Absorption Cooling

● Large UPS System

11) Additional Packaging Requirements

● As briefly mentioned earlier, the system must be packaged or compartmentalized. The packages

must be in a form capable of consolidation for large quantity transportation. The system will use

complex components that are currently manufactured, linking them together in a beneficial way

to reduce space, increase safety, and cost constraints, and the labor necessary to perform the

installation. Because this system could potentially be installed anywhere in the world, a

packaging method suitable for oversea transport is required.

● This requires that the system have shock absorbers attached to critical components

● The exterior packaging of the HEMG system will need to have a commercial coating to protect it

from the elements in case it is installed in an uncovered location

12) Additional requirements resulting from Standards and Regulations (discussed below and where

applicable in further sections.)

Since this system will be designed for rebuilding disaster sites until further infrastructure can be

reestablished, we want to ensure that we are able to get a nominal life expectancy with the system

to ensure minimum maintenance and replacement. In an ideal situation, with a constant supply of

fuel, the nominal life expectancy of the system is 10 consecutive years of operation.

With further thought about where the system will be located, it is uncertain what the temperature

conditions of the system will be. With this vast uncertainty, we elected to design for a wide range

of temperature conditions by requiring all parts to be able to handle temperatures from -10 to 70

Deg Fahrenheit.

The detailed requirement matrix is shown in Table 4.4.1.

4.2 Applicable Standards and Regulations

The EPA published a rule first proposed in September that would cap carbon emissions on new power

plants to no more than 1,000 pounds of carbon dioxide per megawatt hour of energy generated for large

plants, and 1,100 pounds of carbon dioxide per megawatt hour of energy for smaller power plants. The

Capstone MTG achieves nearly complete combustion of all flare and vent gases, effectively eliminating a

majority of the unburned hydrocarbons.

● The MTG exhausts 9 ppm (parts per million) NOx. If MTGs are installed with the Capstone

CARB unit, these levels drop below 4 ppm.

● MTGs are capable of nearly complete combustion; this law will not add any design constraints

UL-2200 covers stationary engine generator assemblies with a voltage rating of no more than 600 volts


51

that are intended for installation and used in ordinary locations in accordance with the National Electrical

Code, NFPA-70; the Standard for the installation and Use of Stationary Combustion Engines and Gas

Turbines, NFPA-37; the Standard for Health Care Facilities, NFPA-99; and the Standard for Emergency

and Standby Power Systems, NFPA-110.

● This standard adds a number of safety requirements, discussed in further detail below

NFPA-70 addresses a number of issues concerning the routing of electrical lines and equipment. Topics

covered in detail are as follows: the installation of electrical conductors, equipment, and raceways;

signaling and communications conductors, equipment, and raceways; and optical fiber cables and

raceways in commercial, residential, and industrial occupancies.

● The electrical conductors, equipment, and raceways; signaling and communications conductors,

equipment, and raceways; and optical fiber cables and raceways electrical systems must adhere to

NFPA-70

NFPA-37 applies to fire safety for the installation and operation of stationary combustion engines and gas

turbines. The standard also encompasses any portable engines or generator sets that connected and remain

in a fixed location for one week or more. This standard addresses a number of topics including gas piping

requirements, engine exhaust systems and clearances to combustible materials, control and

instrumentation requirements on gas turbines, and operating and emergency instruction requirements.

Boosters or compressors, if used, shall be approved for the service intended and receivers, if used, must

be stamped as complying with the ASME Boiler and Pressure Vessel Code. Instruction manuals must be

included for use by non-specialist personnel in case of operation during an emergency.

● The fuel storage system must adhere requirements from ASME Section VIII, Division 2, for

National Board registration and ASME BPVC Section II, EN 13445-2

● NFPA-37 requires that the gas train for engines contains a minimum of a manual shutoff valve,

regulator, low-pressure switch, automatic safety shutoff valve, automatic control valve, manual

leak test valve, and high-pressure manual reset switch with exceptions.

NFPA-99 concerns health care services or systems. These requirements have been set forth to lower the

risk to the patients, staff, or visitors in health care facilities by minimizing the hazards of fire, explosion,

and electricity. This standard sets requirements for installation, inspection, testing, maintenance,

performance, and safe practices for facilities, material, equipment, and appliances, including medical gas

and vacuum

● NFPA-99 adds additional safety requirements for health care facilities. It requires a robust fire

suppression system, standardization of installation, inspection, testing, maintenance, performance,

and safe practices.

NFPA 110 covers performance requirements for power systems (power sources, transfer

equipment, controls, supervisory equipment, and any other related electrical and mechanical auxiliary

equipment) providing an alternate source of electrical power to loads in buildings and facilities in the

event that the primary power source fails. The standard also requires prototype testing of the generator

set. The supplier must show proof of performance under normal and adverse conditions before

installation; this avoids problems otherwise not discovered until the installation startup, or later.

● The MTG must adhere to NFPA 110


52

● The Battery System must adhere to NFPA 110

ASME-B133.8 gives methods and procedures for specifying the sound emissions of gas turbine

installations for industrial, pipeline, and utility applications.

● Intake and Exhaust systems must have baffling to reduce noise to acceptable levels

● Sound proofing must be applied around the gas turbine compartment

Since this system doesn’t fall under well-defined regulations for large-scale power

production facilities like dams and nuclear plants, typical standards are not able to be

directly applied to this project. However, in order to consider possible long-term effects

from the system to the neighbourhood, applicable Environmental Protection Agency standards

were applied. These mainly consisting of ensuring that no hazardous emissions are involved and the

system meets fire safety regulations.

4.3 Validation Methods

In order to evaluate our set requirements, a series of validation methods has to be established. With

conversations with the group sponsor, we were able to derive some methods of validation.

4.3.1 Analysis

Validation via analysis consists of verifying performance by calculations using MATLAB or EXCEL to

ensure applicable requirements are met. The analysis of the plant was done by preparing a

thermodynamic model and performing calculations for various components. It requires a detailed analysis

of a particular component. Mainly the system efficiencies for various loads was studied to determine an

operating mode for maximizing the system runtime.

4.3.2 Solid Modelling

The system layout optimization and weight optimization was validated by a computer generated solid

model using SolidWorks. The model will enable the visualization and configuration of the project layout.

Evaluation of the results will determine if the sizing requirements were met.

4.3.3 Research

Manufactures and suppliers chosen to procure the different system components will also be able to

provide detailed specifications. It is the responsibility of the group to incorporate these specifications in

any detailed system integration analyses. Thus, the research component of the validation process will be

conducted based off of manufacture and industry tested data.

Inspection, demonstration and testing would come into picture if the execution of the project is considered

which currently is out of scope. Further details related to validation of requirements are discussed in the

next section.


53

4.4 Requirements/Validation Matrix

Table 4.4.1 below details the requirements validation matrix. This matrix establishes each system

requirement and details how it would perform during validation testing.



Validation

Validation Result


efficiency = 29.2+/- 0.5 %


3) 75kW @





95kW




exceeds 1000hrs





Hybrid Operation



9) Packaged Size:











times





54

5. Conceptual Design

5.1 Functional Block Diagram

During conceptual design, the team derived a functional block diagram for the designed system. Below is

a figure showing how each component relates to each other, and the energy process and transfers

throughout the system.

Figure 5.1.1 Functional Block Diagram

5.2 Research of Prior Art

For a long period of time, the gas turbine generator is used for large scale power plant. And for small

scale generation of electricity, diesel electricity generators are often used for backup and emergency

power generation.

MicroTurbines are relatively new to the power market, and they have not yet taken a sizable market claim

(in terms of kWs installed). In recent years, microturbines (~30 to 250 kW) have emerged as a promising

alternative to reciprocating engines because of its flexibility. Thus the microturbines have been widely

used in distributed electricity generation, as well as disaster relief. Although the diesel engine has higher

cycle efficiency, considering the flexibility, our primary motivation in selecting a microturbine generator


55

set is to choose a microturbine set rather than a diesel or spark ignition engine. Moreover, what makes the

system unique is that it can be packaged for rapid deployment and optimized to run at a variety of loads (0

- 95kW) for an extended runtime.

Microturbines have several benefits over reciprocating engines, such as

1) Fewer moving parts and maintenance requirements, and

2) Simpler heat recovery (all waste heat is emitted as high temperature exhaust) and quite often have

the additional benefits of

3) Simpler installation,

4) Reduced noise and vibrations, and

5) Lower nitrogen oxides (NOx) and carbon monoxide (CO) emissions.

Because of emissions and vibrations reductions, microturbines have found a niche market where

reciprocating engines are unacceptable or undesirable. A key area of superiority for microturbines over

reciprocating engines is their lower NOx emissions, a parameter of significant environmental concern. In

California, a large market for distributed generation (DG), strict emissions standards that come into effect

in 2007 may preclude reciprocating engines entirely.

5.3. Conceptual Design Options

Given the multi-component nature of this system, the design team faced many potential variations in

component selection. Based off of the simple system requirements, it is decided that the system needs to

produce enough energy to support a maximum 90 kW load efficiently. It is decided that final product will

include a battery system, but the primary function of this system must be better defined. Given these

initial decisions, the design options can be narrowed down to four major focus: power generation, fuel

storage, battery function, and system packaging.

5.3.1.Power Generation

1) MicroTurbine

a. Ideally this system would be used in an urban environment where gas lines are in

tack and easily accessible. This would allow users to utilize available natural gas

and this would eliminate the need to supply fuel.

b. On the down side, this would greatly limit the portability of the system and

would require some technical expertise to connect the system to a gas line.

2) Diesel Generator

a. The most commonly used portable energy generation method. The industry is

large and well established, thus vendors would be competitive and products

would be advanced. Diesel is an easily accessible fuel, and competitively priced.

b. Drawbacks include, a lower high demand power output, and the system is very

heavy.

3) Spark Ignition Engine

a. This option is very similar to the diesel generator in that it is more widely

available thus more competitively priced.


56

b. Drawbacks include fuel limitations and lower power to weight ratio.

5.3.2 Fuel Storage

1) Cylindrical fuel tank

a. Very inexpensive to manufacture and widely available. The cylindrical tank is

the most commonly used fuel storage method.

2) Spherical fuel tank

a. Has a high fuel capacity and is very space efficient. The spherical shape is

structurally sound thus it is less prone to fracturing.

5.3.3 Battery Function

1) High capacity battery to be used during medium to high demand, and recharged during

low demand.

2) Low capacity battery to be used only during very low demand (in place of MTG) or

spike. ‘Floating Charge’ (between 70-90% capacity) maintained via the 30kW MTG.

5.5.4 System Packaging

1) Placing the system on a large flatbed trailer to be towed to the user using a semi-truck.

2) Packaging the system in a shipping container to be air-dropped on site.

5.4 Methods of Selecting Final Conceptual Design

The first step in the selection method was to identify options that can be eliminated by using simple,

logical comparisons. In certain cases, the best option were not apparent, thus additional methods were

used. The ideal method for a more complex case was to use a comparative matrix and analyze the weights

and added value of each proposed component. The Heat Engine was chosen based on this method. After

the categories and weights were established, each group member voted on a rating of 1-10 (10 being best)

on how well the component fits the category. The individual ratings are based on initial research done for

each category. After the ratings were averaged they were entered into a matrix. Finally the points for each

component are calculated using the formula: WEIGHT RATING / HIGHEST SCORE. The weights

and categories are described below.

Out of all the conceptual design options, the power generation system presents the most complex

decision. The remaining three categories are simple two-option decisions. Therefore, the comparative

matrix was used to determine the ideal power generation, and logical comparisons were used for the other

options. The selection rationale for the other options is discussed in greater detail in Section 5.5.

5.4.1 Power Generation Selection Criteria

1) Energy Production

It is the most important aspect of the project since the base requirements are

modeled around the amount of energy the product can provide to the client. In an

emergency situation energy is needed in a large amount. Thus this gets the highest weight

of 35%.


57

2) Running Cost

In an emergency situation the running cost should be minimized so users could

focus more on immediate needs. Even with a high energy production, the product still

needs a low running cost otherwise energy production is diminished. The weight is 20%.

3) Efficiency

This category also goes hand in hand with the two previous categories. Running

cost must efficiently produce a reasonable amount of energy. A low efficiency would

imply that high energy production would require even higher energy costs and fuel

demand. The weight is 15%.

4) Upfront Cost

This is the initial cost of the component. A higher upfront cost would translate to

a higher product cost. The weight is 10%.

5) Safety

Safety is always important in any product but in this case the safety rating is in

relevance to the safety of the product without and safety precautions taken. A major

component of the detailed design is to ensure safety, so if a component is initially unsafe

it will require a greater cost and demand design to make it safer, but ultimately the group

would not produce an unsafe product. The weight is 10%.

6) Size

All of these components will be packaged in a single transportable unit. The

component must be able to fit within the 20x8x8 shipping container. A larger single

component would require smaller additional components to preserve space. Additional

weight should fit the established requirement of 2000 lbs. Larger components have a

smaller rating. The weight is 5%.

7) Uniqueness

This category translates that the allure of the final product. As a product, the

Nomad should bring a unique set of features to the industry that would make client more

interested. The weight is 5%.


58

5.5. Final Selection Comparisons and Rationale

5.5.1 Power Generation

Table 5.1 and 5.2 below detail the selection process and weights for the power generating component of

the system. The highest scoring component is the Gas Line Microturbine, thus this is the final selection.

Table 5.5.1 Categories, Weights, and Team Ratings (1-10) of Each Design Option

Criteria Weights

Gas Line

MT Diesel

Other

Engine Highest Score

Energy Production 35 8 6 6 8

Running Cost 20 9 8 8 9

Efficiency 15 7 5 3 7

Upfront Cost 10 4 9 9 9

Safety 10 1 6 6 6

Size 5 7 5 2 7

Uniqueness 5 10 5 5 10

TOTAL 100 46 44 39 --

Table 5.5.2 Comparison Scores of Each Option After Applying Weights

Criteria Gas Line MT Diesel Other Engine

Energy Production 35.00 26.25 26.25

Running Cost 20.00 17.78 17.78

Efficiency 15.00 10.71 6.43

Upfront Cost 4.44 10.00 10.00

Safety 1.67 10.00 10.00

Size 5.00 3.57 1.43

Uniqueness 5.00 2.50 2.50

TOTAL 86.11 80.81 74.38

5.5.2 Fuel Storage

In order to meet the requirements for this project, the fuel tank should be able to maximize space and size

efficiency. Price is not as important as the tank’s overall weight. Given this consideration, the spherical

tank is much more space efficient, and provides more structural security making it a lighter and safer

option. Thus, the spherical tank is the final selection for the conceptual design

5.5.3 Battery Function

A high capacity battery is alluring because it allows the system to maintain very high emergency demand

loads, but is much heavier than the low capacity battery. Furthermore, the low capacity battery would be

used much more frequently in order to help the system run more efficiently. Using the battery in this

manner would allow the system to support very low loads without having to run the power generation


59

cycle at a low efficiency. Since the low capacity battery is lighter, and supports a more efficient system, it

is ultimately a better option and thus is the final selection.

5.5.4 System Packaging

The two options for system packaging are truck-bed placement, and shipping container storage. Using a

truck bed would allow for inexpensive and convenient transportation, but would require a lighter load. A

shipping container would requirement more expensive transportation as well is a load drop shock

absorption system, but would allow for a heavier system and greater accessibility. Ultimately, since the

shipping container allows for larger loads and would enable delivery to more locations, it is the prefered

option despite the increase in cost.

5.6 Description of Final Conceptual Design

Figure 5.6.1: Conceptual Block Diagram

5.6.1 Microturbine Set Description

Micro-turbines offer many beneficial characteristics depending on the various needs and the particular

application including fuel flexibility, low NOx emission levels, low maintenance costs and requirements,

compact size, and quiet operation (Hamilton, 2003). For the established requirements, types of generator

satisfying the requirement are micro-turbine and diesel generator. Although diesel generator can be

applied in this kind of demands, considering that diesel generators has high frequency for maintenance as

well as limited range of temperature to guarantee continuous work, micro-turbine is selected.


60

For output under 100 kWh, two manufacture, Capstone Turbine and Elliot Turbine, have products which

satisfy the demand. Capstone Turbine has microturbines available in the following sizes: 30 kW, 60 kW,

65 kW, and etc., and Elliot offers turbine for 100 kWh. (Capstone Inc., 2005) Capstone Turbine is the

pioneer in the development of the microturbine which has the most mature commercial products on the

market. Considering budget of weight and dimension, output, runtime, efficiency, and other issues, from a

series of trade studies, the combination of one set Capstone C30 and one set Capstone C65 is the best

solution among other possible combination which gives power output for 30kW, 65kW, and 95kW

(during standard day: 59F, 30%RH).

The most remarkable beneficial characteristics of microturbine chosen are fuel flexibility and low NOx

emission levels. For fuel flexibility, both C30 and C65 can run on natural gas as well as a series options

such as biogas, flare gas, diesel, propane, kerosene, and aviation. Though type of fuel can affect the

performance of microturbine as well as economics of application, it’s really helpful when this system is

set in emergency use. For low NOx emission level, the Capstone C30 and C60 microturbine at full load is

less than 9 ppm, a NOx level significantly lower than existing and entrenched diesel generators.

Some basic but significant specifications of power and electricity performance are listed in the following

tables.

Table 5.6.1 Performance Ratings at Full Load Power and ISO Conditions (Grid Connection Mode)

Product Net Power Output Net Efficiency

(LHV) Nominal Net Heat

Rate (LHV)

Nominal Generator Heat

Rate

Model C30 (HPNG, SG,

or L/DG) (without

gas compression

option)

30 (+0/-1) kW net 3 Phase 400/480 Volts AC

46 A per phase max continuous, 50/60 Hz

26 (± 2)% (Efficiency values

might be lower if

fuel gas compression is

required for L/DG)

13,800 kJ (13,100 Btu /kWh)

12,800 kJ (12,200 Btu/kWh)

Model C65 (HPNG) (without gas

compression

option)

65 (+0/-2) kW net 3 Phase 400/480 Volts AC

100 A per phase max continuous, 50/60 Hz

29 (± 2)% 12,400 kJ

(11,800 Btu /kWh) 11,600 kJ

(11,000 Btu /kWh)

(Ref: http://www.globalmicroturbine.com/pdf/brochures/capstone_specs.pdf)

Table 5.6.1 gives the performance of C30 and C65, the efficiency of each microturbine can be obtained as

28% (C30) to 29% (C65). In this project, the working mode or microturbines are standalone with

combining modes. The table below gives electricity performance in Standalone Mode.


61

Table 5.6.2 Electrical Performance Ratings in Standalone Mode (Capstone, 2005)

Parameter Model C30 Model C65

Net Power Output 30 (+0/-1) kW net 38.2

kVA max at 480 VAC 65 (+0/-2) kW net 83

kVA max at 480 VAC

Nominal Voltage

Operating Range 400 to 480 VAC 400 to 480 VAC

Frequency Operating

Range 10 to 60 Hz 10 to 60 Hz

Output Voltage

Connection

3-phase, 4 wire wye (Neutral must be solidly grounded)

3-phase, 4 wire wye (Neutral must be solidly grounded)

Output Current (1)

46 Amps RMS maximum

steady state 125 Amps RMS maximum

steady state

Voltage THD IEEE 519 Compliant, 5% IEEE 519 Compliant, 5%


From above tables, both microturbine supplies power voltage from 400 to 480 VAC, and the range of

frequency reaches from 10 to 60 Hz. Considering different situations with different temperature, the

efficiency may decrease do to the increase of ambient temperature. The temperature effect also applies to

performance of power output. Below are curves plotted for temperature effect on output and efficiency for

C30. Due to the exactly similar structure, the effect of temperature for C65 is almost same. Therefore, the

curves are plotted in appendix.

Figure 5.6.2: Net Power Output for Capstone C30 vs. Ambient Temperature


http://www.globalmicroturbine.com/pdf/brochures/capstone_specs.pdf



62

Figure 5.6.3 Net efficiency for Capstone C30 vs. Ambient temperature


Figure 5.6.2 and 5.6.3 show that, the microturbine is sensitive to temperature. And the best working

temperature is below 65 F. As temperature increases to such extreme situation such as 120F , the power

output drops by 23% and the efficiency drops by 22%.

At above 65% power, both microturbines have a fuel flow rate is highly linear proportional to the output

of electricity. If gas fuel is stored at 5500 psi, we can estimated that for 51.3217 cube feet spherical tank,

for different output modes as 30kW, 65 kW, and 95 kW, the running time is 47 hours, 17 hours, and 12

hours.

The table listed below denotes the Equipment and installed cost in 2007. Since all microturbines and

accessories will be installed by the group, the majority of cost of microturbine is package and material

cost.

Table 5.6.3: Reference Cost from 2007 (EEA,2008)

Cost Capstone C30 Capstone C65 TOTAL

Equipment Cost / kW (2007) $1,290 $1,280 $2,570

Material and Installation / kW $470 $370 $840

Total Plant Cost /kW $52,800 $107,250 $160,050

(Ref: http://www.epa.gov/chp/documents/catalog_chptech_microturbines.pdf)

Therefore from the above table, the total cost for the microturbine generator set (Capstone C30 + C65) is

$160,050.



63

5.6.2 Fuel Type/System Description

Advantages of using natural gas (PSEG, 2014)

1) Natural gas is the cleanest burning fossil fuel. Because the combustion process for natural gas is

almost perfect, very few byproducts are emitted into the atmosphere as pollutants. Also, with the

introduction of new technologies, nitrogen oxides, pollutants targeted by the Clean Air Act can

be significantly reduced. The blue flame seen when natural gas is ignited is a sign of perfect

combustion.

2) Switching to natural gas eliminates the need for an underground storage tank--eliminating the

threat of oil spills, soil contamination and costly environmental clean-up.

3) If the oil tank is above ground, switching to natural gas eliminates worry about spills or

corrosion of the tank. And, there's no unsightly storage tank to clutter the appearance of the

property.

Advantages and details of using natural gas

1) Jet Propulsion No.8 (JP-8) is a jet fuel made by refining crude petroleum. The primary ingredient

in JP-8 is kerosene, which is about 99.8% by weight.

2) JP-8 is a jet fuel used in U.S. military aircraft, vehicles, and other equipment (Fact sheet JP-8,

2002).

3) It is a replacement for the JP-4 fuel; the U.S. Air Force replaced JP-4 with JP-8 completely by the

fall of 1996, in order to use less flammable, less hazardous fuel for better safety and combat

survivability (Oilgae, 2014)

For the conceptual design, the team selected a spherical tank to act as the fuel container.

A sphere is the most efficient pressure vessel because it offers the maximum volume for the least surface

area and the required thickness of a sphere is one-half the thickness of a cylinder of the same

diameter.The stresses in a sphere are equal in each of the major axes, ignoring the effects of supports. In

terms of weight, the proportions are similar. When compared with a cylindrical vessel, for a given

volume, a sphere would weigh approximately only half as much. Spheres are economical for the storage

of volatile liquids and gases under pressure, the design pressure being based on some marginal allowance

above the vapor pressure of the contents.

The vessel assembly is custom designed using the specifications and requirements from ASME Section

VIII, Division 2, for National Board registration.ASME BPVC Section II, EN 13445-2. NFPA-37

requires that the gas train for engines contains a minimum of a manual shutoff valve, regulator, low-

pressure switch, automatic safety shutoff valve, automatic control valve, manual leak test valve, and high-

pressure manual reset switch with exceptions.For the requirement of entire system, the max major

diameter is 7ft and use it as the diameter of selected tank.


64

5.6.3 Battery System Description

Considering the requirements of battery system, we need a stable and durable battery system which can

provide us the load diversity. The key requirement is more than 60min output at 10 kW. Additionally it

should fit the dimension and weight budget.

The battery runtime is a function of output. Below in Figure 5.6.4 is a graphical summary of runtime

versus output for various models and loads and the selected component is highlighted in red. Also, there

are some more options. The best choice is the SYCFXR8. From this figure, we can determine that the best

choice is the SYCFXR8 from battery system's runtime.

Figure 5.6.4 The Runtime vs. Loading Chart

(Ref: http://www.apcmedia.com/salestools/GSIG-8SEBUA/GSIG-8SEBUA_R0_EN.pdf)

Table 5.6.4 The Input Specifications

Requirement 40 kW System

Connection type 3PH + N + G

Input voltage (V) 3-Phase 208 V (166 V - 240 V)

Input frequency (Hz) 40-70

THDI <6% at full load

Nominal input current (A) 123

Maximum input current - continuous, at minimum

mains voltage (A) 154

Maximum Short Circuit Withstand (kA) 30



65

This battery system has variable input mode. But it is still running in different voltage than the gas

turbine. To solve this requires the implementation of a transformer to properly correct the input voltage

and current.

Table 5.6.5 The Output Specifications

Output voltage 208 V

Connection type 3PH + N + G

Overload capacity 150% for 30 seconds (normal operation)

150% for 30 seconds (battery operation)

125% continuous (bypass operation)

1000% for 500 ms (bypass operation)

Nominal output current (A) 111

Maximum output current (in bypass only at 125% overload,

per phase)(A)

139

Neutral output current with 100% switch mode load (A) 192

Output frequency (on line, in bypass) Synchronized to input over the range 57 Hz

– 63 Hz

Output frequency (on battery)(Hz) 50/60

Slew rate (Hz/s) Programmable to 0.25, 0.5, 1, 2, 4, and 6

THDU < 2% linear

< 5% non-linear


The battery system has an alternate output: 139 Amperes for 15 minutes. This will make the whole

system more durable and stable.


66

5.6.4 Safety System Description

This safety system utilizes Carbon Dioxide (CO2) as the primary fire suppression agent. CO2 is a

colorless, odorless, and chemically inert gas that is both readily available and electrically non-conductive

(Carbon Dioxide Properties, 2003). It extinguishes fire primarily by lowering the level of oxygen that

supports combustion in a protected area. This mechanism of fire suppression makes CO2 suppression

systems highly effective, requiring minimal clean-up. All of these advantages are suitable for our system

which includes combustible gas (natural gas) and electrical equipment.

Summary of System Requirements

The safety system has the task of monitoring the functional components of the facility for potential fire

threats as well as operating a CO2 fire suppression system in the event of a fire (Janus Fire Systems

2013).

System Specifications

The CO2 in each suppression tank weighs 75 lbs , the empty weight is 160 lbs, the height of the

extinguisher is 61.1 inch, and the width of each extinguisher is 9.2 inch. These specifications are

summarized below.

Table 5.6.6: Sizing for Cylinder Options

Nominal Cylinder Size(CO2) Empty Weight Full Weight Height Width

75 lbs. 160 lbs. 235 lbs. 61.1 in. 9.2 in.

(Ref: http://www.janusfiresystems.com/products/Carbon-Dioxide-co2)

After calculation mentioned in appendix, we need three such size cylinders to guarantee that the fire

extinguisher can be able to clean the volume 3 times.

Due to requirement that the suppression needs to have the capacity of us for three times, we need to

mount three cylinders. The total mass and weight of CO2 is 225 lbs and 705 lbs, respectively. The height

is 61.1 inch and the length is 27.6 inch. These data are shown in the table named weight for the

suppression options. Table 5.6.7: Weight for Cylinder Options

Nominal Cylinder Size(CO2) Empty Weight Full Weight Height Length Width

lb lb lb in in in

225 480 705 61.1 27.6 9.2

(Ref: http://www.janusfiresystems.com/products/Carbon-Dioxide-co2) 5.6.5 Packaging Description

The packaging in this system contains one shipping container made of aluminum alloy in size of 20

[in] 8 [in] 8 [in], which weights for 5,015 lbs. All components of the system is packaged in the

container.


67

5.7 Analysis

5.7.1 Gas Generator Selection and Rational

A diesel engine has the highest thermal efficiency of any standard internal or external combustion engine

due to its very high compression ratio. We considered a configuration of 3 diesel engines of 30 KW

capacity to meet our power output requirement. However its maintenance has been looked into and there

have been some visible hazards. Fuel injection introduces potential hazards in engine maintenance due to

the high fuel pressures used. Residual pressure can remain in the fuel lines long after an injection-

equipped engine has been shut down. This residual pressure must be relieved, and if it is done so by

external bleed-off, the fuel must be safely contained. If a high-pressure diesel fuel injector is removed

from its seat and operated in open air, there is a risk to the operator. Also due to the stringent weight

requirements we had to drop the option and look into gas turbines.

Micro Turbine is a gas turbine of an internal combustion engine. We considered this option since we

found some advantages to our system over diesel generator. Firstly it has very high power-to-weight ratio,

which makes its suitable to meet the weight and dimensional budget of the system. Smaller than most of

the diesel engines of the same power rating. Also the microturbines that we are considering have greater

reliability, particularly in applications where sustained high power output is required. The maintenance

hazards are also reduced due to low operating pressures. Also since the system needs to adaptable to

different fuel types due to its mission requirement of being deployed anywhere, turbines that can run on a

wide variety of fuels are preferred.

Figure 5.7.1 Structure of Capstone Micro Turbine

(Ref:http://en.wikipedia.org/wiki/Capstone_Turbine)

However, we still kept facing problems with weight and space overshoot and had to look at alternative

system configuration of microturbines.

We looked into the available microturbines in different power capacities and realized that we could use a

configuration of 1 x 30 KW and 1 x 65 KW capacity in combination. This has inherent advantage, saving


68

weight and space and also further analysis revealed benefits in terms of higher efficiency and improved

runtime compared to earlier generator combinations.

Table 5.7.1 Micro Turbine Trade Study

Decision Factors

Alternatives Ranking

Weigh

t

3 Capstone

C30

2 Capstone

C65

1 Capstone

C30 & 1

Capstone C65

Elliot

Rankin

g

Weight

Rankin

g

Rankin

g

Weight

Rankin

g

Rankin

g

Weight

Rankin

g

Rankin

g

Weight

Rankin

g

Weight budget 8 0.98 7.84 0.76 6.08 1 8 0.83 6.64

Dimension budget 5 0.76 3.8 0.89 4.45 1 5 1 5

Max. Power Output 5 0.69 3.45 1 5 0.73 3.65 0.77 3.85

Power Output

Adjustability 6 0.98 5.88 0.76 4.56 1 6 0.63 3.78

Max. Runtime 5 1 5 0.77 3.85 1 5 0.57 2.85

Input source 2 1 2 0.9 1.8 0.9 1.8 0.7 1.4

Manufacturers 2 1 2 1 2 1 2 0.7 1.4

Efficiency 7 0.86 6.02 1 7 0.9 6.3 1 7

Acoustic Emissions 1 0.32 0.32 0.44 0.44 0.46 0.46 1 1

Operation Flexibility 4 0.57 2.28 0.7 2.8 0.7 2.8 1 4

Safety 5 1 5 0.9 4.5 1 5 0.8 4

Maintenance 2 1 2 1 2 1 2 0.8 1.6

Weighted total 52

45.59

44.48

48.01

42.52

Figure 5.7.2 Capstone Microturbine C30 of C60


69

5.7.2 Battery System Selection and Rational

Table 5.7.2 Trade Study: Battery System

Decision Factors

Alternative Ranking

Weig

ht

APC Symmetra PX 125-

250kW

APC Symmetra PX 10-

40kW

APC Symmetra PX

10+SYBFXR8X

Ranking Weight

Ranking Ranking

Weight

Ranking Ranking

Weight

Ranking

Within weight

budget 10 0.5 5 1 10 0.9 9

Within dimension

budget 10 0.5 5 1 10 0.9 9

Power Output 10 0.8 8 0.5 5 0.5 5

Runtime 10 0.9 9 0.3 3 0.7 7

Maintenance 5 1 5 1 5 1 5

Safty 10 1 10 1 10 1 10

Efficiency 8 0.98 7.84 0.94 7.52 0.94 7.52

Weighted Total 63 49.84 50.52 52.52

Figure 5.7.3 Battery System


70

5.7.3 Fuel System Selection and Rational

Rework and optimization during the preliminary design excluded a pressurized gas fuel system from the

design. It was determined that a liquid fuel would provide the system with a much higher runtime.

Table 5.7.3 Fuel System Trade Study

Decision Factors


Weight

Customized Natural

Gas Storage Tanks

Steel Large Capacity

Natural Gas Storage

Tanks

Type4 Natural Gas

Storage Tank

Ranking Weight

Ranking Ranking

Weight

Ranking Ranking

Weight

Ranking

Heat Value of fuel 10 0.9 9 0.9 9 0.8 8

Cost 8 0.7 5.6 0.6 4.8 0.7 5.6

handling 6 0.8 4.8 0.6 3.6 0.9 5.4

Multiple fuel

usage(Natural/LPG) 6 0.8 4.8 1 6 0.8 4.8

Fuel tank capacity 9 1 9 0.8 7.2 0.9 8.1

Fuel tank dimension 7 1 7 0.8 5.6 0.7 4.9

Fuel tank weight 8 1 8 0.6 4.8 0.8 6.4

Weighted total 54

48.2

41

43.2

Figure 5.7.4 Spherical Tank

(Ref:http://www.rainharvest.com/norwesco-325-gal-underground-sphere-cistern.asp?gclid=CNusr5Tp-

r0CFQKSfgod-IQAZQ)


71

5.7.4 Safety System Selection and Rational

Comparing the relevant products in different companies, we decided to choose Janus fire suppression

for our system due to the suitable dimension, weight and high efficiency which has been shown in

the table below.

Table 5.7.4 Trade Study : Safety System

Decision Factor Weight


KEVTA Fike Western States Co.

Ranking Weight

Ranking Ranking

Weight

Ranking Ranking

Weight

Ranking

Weight Budget 5 0.5 2.5 0.6 3 0.5 2.5

Dimension Budget 7 0.6 4.2 0.7 4.9 0.5 3.5

Clean-up 9 0.9 8.1 0.7 6.3 0.9 8.1

Efficiency 9 0.8 7.2 0.8 7.2 0.9 8.1

Human exposure

hazard 5 0.9 4.5 0.9 4.5 0.9 4.5

Capacity 8 0.9 7.2 0.9 7.2 0.7 5.6

Easy-handling 4 0.8 3.2 0.9 3.6 0.8 3.2

Cost 8 0.6 4.8 0.5 4 0.7 5.6

Experience 6 0.9 5.4 0.4 2.4 0.3 1.8

Available Options 5 0.7 3.5 0.4 2 0.8 4

Weighted total 66

50.6

45.1

46.9

The connection of the safety suppression system is given in the next page.

Figure 5.7.5: Fire Suppression Safety System

(Ref: http://www.janusfiresystems.com/products/carbon-dioxide-co2)


72

5.8 Proof of Concept Testing

5.8.1 Test Plan

In the case of this preliminary design project the test plan is to manufacture a pilot unit by packaging the

specified components onto a skid in the critical dimensions in order to perform a proof of concept (POC)

demonstration. The expected outcome of the POC test is that the unit will function properly with the

given component configurations, however rework will likely be necessary with respect to running the

electrical and fuel lines in a consolidated fashion, although this work can be done accurately beforehand

using Solidworks.

5.8.2 Mean Time Between Failure (MTBF) Testing and Prediction Models

It will be necessary to have prediction models for the Mean Time Between Critical Failure (MTBCF),

however, for most of the components, these statistics can be retrieved from the manufacturer before any

testing takes place. Mean Time Between Unit Replacement (MTBUR) will also be of interest. Although

data from the manufacturer will prove useful, the POC prototype must undergo longevity and fatigue

testing and subsequent analysis in an effort to measure the above mean times. With this information, a

scheduled maintenance plan could be fully developed on a component to component and system wide

basis.

5.8.3 Drop Testing

Some of the components, namely the microturbine, are inherently sensitive to drops. The object of

primary interest is the MT air bearing; a large impact will likely cause damage. Other components that are

vulnerable due to the configuration are the fuel storage and delivery system. The HEMG utilizes shock

absorbers with three dimensions of freedom to avoid damage to these components, however fine tuning

this system would be key in preventing incident upon delivery. The drop testing methods include free fall,

corner and edge drops. Provided Capstone has not already done so, we would like to develop a test rig

with the same air bearing a shaft used in the microturbine to determine the systems resiliency to the

aforementioned impacts.


73

5.9 Cost of Electricity and Weight Model for Conceptual Design

Table 5.9.1 COE and Weight Model

Component/System Cost Weight

Capstone C30 $38,700 1,271 lbs

Capstone C65 $83,200 2,471 lbs

APC UPS $33,000 1,717 lbs

Spherical Fuel Tank $9,500 3,000 lbs

5,500PSI NG Compressor $25,000 850 lbs

Janus Fire Suppression $2,500 705 lbs

Shipping Container $3,000 5,000 lbs

Communications and Monitoring Eq. $4,000 50 lbs

Miscellaneous Items:

-Additional Structural Members

-Fuel Lines, Gas Train,

-Insulation, Ducting, Filtration,

-Electrical Equipment, Wiring,

-Circuit Breakers

$30,000 1,000lbs

Estimated Manufacturing Price $140,000

Maximum Fuel Capacity NG @ 5,500 1034.8lbs

Totals: $278,900 17,098.8 lbs

Remaining Weight for Fuel ~ 3,000 lbs

Table 5.9.2 COE Model Factors

Cost of Electricity Model Factors Price/Factor

Rated Capacity 95kW

Capital Investment $278,900

Capacity Factor (Depends on Deployment, Sales) 0.1 - 1

Efficiency 0.2817%

Fixed Charge Rate 0.1

Fuel Cost 4.61/MMBtu

Operation and Maintenance 0.015 $/kWh


74

Fixed Charges = (Fixed Charge Rate + Capital Investment)/(Rated Capacity * Capacity Factor * 8760

hrs/year)

Fixed Charges = $0.0335519/kWh (HIGH USAGE)

Fixed Charges = $0.335519/kWh (LOW USAGE)

Fuel Charges = (Fuel Cost * 10^-6 [Btu/MMBtu] *3414)/Efficiency

Fuel Charges = $ 0.0558699/kWh

COE = Fixed Charges + Fuel Charges + Operation and Maintenance

COE = $0.104421/kWh (HIGH USAGE)

COE = $0.406389/kWh (LOW USAGE)


75

6 Preliminary Design and Optimization

6.1 Final Configuration Block Diagram

The configuration diagram shown in the Fig. 6.1.1 shows the block diagram for the final design of the

system. The fuel is stored in a bladder and is supplied to the two gas turbines during operation. The 2 gas

turbines would operate in different modes in combination with the battery depending on which mode the

system is operating in. Transformer would be used to step down the high voltage output coming out

through the turbines. The transformer feeds in power into the UPS Battery. This battery performs the job

of storing energy and outputs DC electricity for the fire suppression system, monitoring system, safety

system, and communication system. In case the system operates at low loads, the output lower than 30

kW will come from the battery system. We have also included an exhaust duct as a part of our system.

Figure 6.1.1 Final Configuration Block Diagram

6.2 Analysis Plan

Given below is the analysis plan through which the project is planned to progress after the pre-concept

was developed. The project plan was made only upto the preliminary stage due to the scope restrictions.

The team performed a thorough research about the hybrid power supply systems, safety systems,

industrial standards and regulations and the a mission requirement in the form of a demand profile. After

we chose the Gas turbines as the best choice for the heat engines some thermodynamic calculations were

made to verify expected performance. The other systems were also finalized after some trade offs and

with this the conceptual stage was completed. Further on the runtime which is the key parameter was


76

optimized and the performance was characterized. The Final PReliminary Design was proposed after the

requirements list was validated.

Figure 6.2.1 Analysis Plan

6.3 Failure Modes and Effects Analysis

The Failure Modes and Effect Analysis (FMEA) is a list of parts in the assembly that are susceptible to

failure and potentially damage or disable the system. The table consists of tabulated data measuring

various factors such as failure mode, probability of failure, level of severity, end effect, and risk priority

number. The risk priority number, RPN, is a measure of design risk that is the product of the severity,

detection, and occurrence.

There is a table that lists designated numbers for the severity, detection, and occurrence based on a 1 to 10

scale. Severity is an assessment of the seriousness of an effect of potential failure mode. Detection is a

design control put in place to anticipate and correct possible issues with the assembly. Occurrence simply

refers to the likelihood that a specific cause/mechanism will occur.

Once the risk priority number has been determined through the FMEA process, steps must be taken to

improve the assembly and minimize the RPN. The amount of information contained in the FMEA is too

large to properly format in Microsoft Word and will be in the appendix.


77

Table 6.3.1 Top 5 FMEA Summary

Failure

Mode Part

Name Function Potentia

l Failure

Mode

Potential

Failure

Effect

SEV Potentia

l Causes OCCUR Current

Design

Controls -

Prevention -

Detection

DETECT RPN

Failure

Mode 1 Turbin

e Master

Generato

r

Burning Catastrophi

c Damage 9 Incorrec

t

Operatin

g

2 Spark detector

and Fire

suspension

system

4 72

Failure

Mode 2 Turbin

e C30 Slave

Generato

r

Break

Down Power

output

reduction

by 30 kW

6 Overloa

d caused

fracture

3 Using battery

system along

with the C30

2 36

Failure

Mode 3 Battery Store the

power Leakage Structure

corrosion

and

lowering

the

efficiency

4 Long

time no

use

7 Programming

the computer

to

automatically

start the

turbine to

charge the

battery every

3 month

1 28

Failure

Mode 4 Fuel

Tank Store the

fuel Leakage Loss of fuel

and system

down

8 Punctur

e during

airdrop

1 Using high-

tech self

sealing tank

by Aerotek tm

2 16

Failure

Mode 5 Packag

ing

unit

Contain

and

protect

the

system

Broken Can not

protect the

unit any

longer

2 Seal

failure 1 Using

aluminum

structural

member

1 2

6.3.1 Thermodynamic Model

In this system, the thermodynamic model involved is a typical brayton cycle with a recuperator which is

denoted by point 3 and 6. There exist losses in the compressor, turbine and recuperator, and the dash lines

in the state point curve in T-S diagram denotes the process with compressor, and turbine efficiencies

while the solid line denotes the ideal brayton cycle.

Air from ambient environment goes into the compressor being compressed and then goes into

recuperator. After being heated in the recuperator, the air is mixed with the fuel and goes directly in to the

combustor. In the combustor, the chemical energy of fuel is rapidly transferred to heat of the air mixture,

and the highly heated air pushes the turbine changing the heat to the shaft work, which can be converted

to the electricity via generator module. Exhaust gas exits the turbine goes back to another side of the

recuperator, heating the compressed inlet air. Then exhausted air exits the recuperator. The specifications

of Capstone C30 is given in the table 6.2.1, and the thermodynamic calculation is based on this table.


78

Figure 6.2.1 States of brayton cycle (Hamilton, 2003)

Table 6.3.1: Data reported in University of Colorado study. (Johansen, 2013)

Pressure ratio 2.4

Compressor Isentropic Efficiency 70.00%

Turbine Isentropic Efficiency 81.00%

Recuperaor Effectiveness 81.00%

Pressure drop over recuprator, relative 7.50%

Electrical Efficiency 21.80%

Fuel input 48.06 kW = 163987.54 BTU/hr

mass flow air 0.17 kg/s = 0.3747 lb/s

(Ref: http://brage.bibsys.no/xmlui/bitstream/handle/11250/183107/Johansen_Paal_Andre)

Table 6.3.2 shows a Capstone C30 study in University of Colorado, which tested the temperature of the

fully loaded C30 microturbine at each state point. Finally after calculation, we find the results is in the

range which Capstone listed in the specification sheets. The derivation of calculation is listed in the

appendix, and the efficiency of 27.2% at 59 F and 18.2% at 120F.


79

Table 6.3.2: Temperatures reported in University of Colorado study (Johansen, 2013)

T1 Compressor inlet temperature[1]

68 oF 527.67

oR

T2 Compressor outlet temperature 282.2 oF 741.87

oR

T3 combustion chamber inlet temperature 960.8 oF 1420.47

oR

T4 Turbine inlet temperature 1407.2 oF 1866.87

oR

T5 Turbine outlet temperature 1121 oF 1580.67

oR

T6 Recuperator outlet temperature 827.6 oF 1287.27

oR


6.4 System Optimization

The battery size of the system was optimized for runtime based on the low demand section of the mission

profile shown below in Figure 6.4.1. As you can see, the size of the battery directly relates to an increase

in efficiency at that level of output. After the demand reaches the maximum output capacity of the

battery, the curve drops to the efficiency curve of the C30 microturbine.

Figure 6.4.1 Efficiency Curve for the system over the mission profile. Various batteries are used to increase the

efficiency at low outputs.


80

The team selected the battery that gave the longest mission profile runtime with 3 days of 95kW ouput

remaining. As can be seen in figure 6.4.2, the study was insensitive for battery size, and thus the 10kW

battery was selected as the optimal runtime solution.

Figure 6.4.2 Runtime Curve

6.5 Proof-of-Concept Testing

● (Is beyond the scope)

6.6 Trade Studies

From the early stages of the design, a Functional Block Diagram was used to represent different

functional components. This was purposed towards keeping the design space open so that a variety of

different options and approaches could be considered before the preliminary phase. That being said, there

were some design paths taken that eventually led to a ‘dead end,’ but the team was not afraid to take an in

depth look at the problem and rework through analysis and options in order to refine the design towards

the optimal solution. One example of drastic rework that took place was in the design of the fuel system.

Entering the preliminary design phase, the “Fuel Storage” functional block was a pressurized spherical

tank for holding natural gas. Upon detailed analysis and further design, it was clear that the tank was

suboptimum for a number of reasons. Upon realizing this, the team stepped back to the functional block

to rework towards a better solution, which quickly became clear after some rework. Figure 6.4.2 is a

visual map of the process that took place during this design.


81

Figure 6.4.2 A summary of the trade studies, optimizations and rework

that led to the optimum design for the given problem statement, requirements, and constraints.

● (See Appendix H for additional information)


82

7. Project Performance

The project performance section outlines how relevant the project remained to the projected schedule

outlined in Section 3. In this section we outline how the project was tracked using performance metrics,

how many man hours were spent on the project, and the key things that were learned.

7.1. Project Metrics

In order to evaluate the successfulness of this project, measurable metrics have to be created

and observed. One of these is setting up a project schedule and recording when time was

allocated to a particular task. This schedule is below in figure 7.1.1. As noted beforehand, an initial

project schedule was created to outline the entire project scope. Below is the finalized project schedule for

both semesters. The final program schedules show in Figure 7.1.2, summarizes the work done through the

semester and the timelines for completing the required tasks.

Figure 7.1.1 Completed Project Schedule


83

Figure 7.1.2 Total projected hours versus actual project man hours

The team started off a pretty fast with actual manpower hours shooting above as compared to what had

been budgeted. The optimization phase was more or less in shape by the week 9. Since most of the work

was done then the hours needed after week 10 were less and timelines could be met even without the need

to put in the given number of projected hours. Since we followed an electronic method of documentation

changes could be made in real time by everyone and helped the team function much more efficiently. We

were well on track to complete everything on time.

7.2. Key Learnings

During the analysis and performance optimization the team also had to tackle with the final report and

presentation for the assessment fair coming at the end of the semester. The thoroughness of the report,

although exhausting, gave insight to the importance of analysis and presentation in industry. It’s a

realization that even though something can be successfully analysed, a large

portion of the work required in order being entirely successful lies within how well it can be

presented to an investor or sponsor.

Also through different stages of the project the understanding of working in a multicultural team became

more clear which gave us an introduction to working in global communities. It enhanced our interpersonal

skills at a great level.

The project being a very diverse system, we had to research a lot about various uncertainty factors that are

needed to be taken into consideration. We learnt to think laterally about engineering problems through

this.


84

8. Project Conclusions

Nomad design was successful in designing a system to meet Randy Roberson’s needs. The prototype

meets the majority of the significant requirements, with others capable of fulfillment with further research

and development (such as the center of gravity). The preliminary design is ready for a proof of concept

model for establishing actual specifications and a process for manufacturing.

Upon further review of the design process followed by team Nomad, there were definitely instances

where communication might have been improved. In addition, some design ‘mistakes’ were made that

could have been avoided with proper research and analysis - or the application of a ‘trained eye.’ That

being said, this project was success because the team understands that learning by application is

extremely necessary in the complex field of engineering.

9. Recommendations

Team Nomad must develop a business plan based on a ‘pay for availability’ concept. Further work with

Randy Roberson will be necessary to determine the logistics of deploying the HEMG systems. They must

then seek investors who will sponsor the production of HEMG units. These units will be kept in Tempe,

Arizona, just 15 minutes from the Phoenix International Airport, and when the time and need arise, they

will be sent to the appropriate location and begin aiding first responders.


85

References

Hamilton, S., 2003. The handbook of microturbine generators. 1st ed. Tulsa, Okla.: PennWell.

Various Contributors. "Capstone Turbine Corporation." Capstone Turbine Corporation. N.p., n.d. Web. 1

Apr. 2014. <http://www.capstoneturbine.com/>.

Nascimento, et al. 2013. Progress in Gas Turbine Performance. Rijeka, Croatia: InTech

Various Contributors. "APC by Schneider Electric." American Power Conversion Corporation. N.p., n.d.

Web. 1 Apr. 2014. <http://www.apc.com/>

Giampaolo, Tony. The Gas Turbine Handbook: Principles and Practices. Lilburn, GA: Fairmont, 2003.

Print.

Kreith, Frank. The CRC Handbook of Mechanical Engineering. Boca Raton: CRC, 1998. Print.

Moran, Michael. Introduction to Thermal Systems Engineering. United States of America: John Wiley &

Sons, Inc., 2003.

National Academy of Engineering (NAE), Various Contributors. "Grand Challenges - Engineering

Challenges." Grand Challenges - Engineering Challenges. N.p., n.d. Web. 1 Apr. 2014.

<http://www.engineeringchallenges.org/cms/challenges.aspx>.

Pulkrabek, Willard W. Engineering Fundamentals of the Internal Combustion Engine. Upper Saddle

River, NJ: Pearson Prentice Hall, 2004. Print.

Trimble, Steve - Professor of Practice. "Internal Combustion Engines, Energy System Design at Arizona

State University." Lecture Hall. Tempe East Campus. 2010-2014. Lecture.

T.-W. Lee - Associate Professor. "Thermodynamics at Arizona State University." Lecture Hall. Tempe

East Campus. 2010-2014. Lecture.

Various Contributors. "U.S. Energy Information Administration - EIA - Independent Statistics and

Analysis." U.S. Energy Information Administration (USEIA). N.p., n.d. Web. 09 Feb. 2014.

Various Contributors. "The Advantage of Natural Gas" Public Service Enterprise Group (PSEG). N.p.,

n.d. Web. 1 April. 2014.

"Phase change data for Carbon dioxide". National Institute of Standards and Technology. Retrieved 2008-

01-21

W.Q.Zhang, Layout and design of Carbon dioxide fire extinguishing system. JiaoTong University. 2010


86

Other Website References:

http://www.americanprogress.org/issues/green/report/2013/04/29/61633/disastrous-spending-federal-

disaster-relief-expenditures-rise-amid-more-extreme-weather/


87

APPENDIX

APPENDIX A - Microturbine Generator Specifications and Calculations

Table A1: Data reported in University of Colorado study. (Johansen, 2013) (Ref: http://brage.bibsys.no/xmlui/bitstream/handle/11250/183107/Johansen_Paal_Andre)

Figure. A1 States of thermodynamic cycle (Hamilton, 2003)

Pressure ratio 2.4

Compressor Isentropic Efficiency 70.00%

Turbine Isentropic Efficiency 81.00%

Recuperaor Effectiveness 81.00%

Pressure drop over recuprator, relative 7.50%

Electrical Efficiency 21.80%

Fuel input 48.06 kW = 163987.54 BTU/hr

mass flow air 0.17 kg/s


88

Table A2: Temperatures reported in University of Colorado study (Johansen, 2013)


The University of Colorado is situated at around 1600 meters above sea level, and the lower ambient air

pressure and density causes the power output of the turbine to drop about 20%. (Johansen, 2013) This

efficiency drop is caused by the reduction in air density. The data reported was for lower loads than we

would expect for our plant. Load performance of gas turbines are poor, so this has a large effect on the

efficiency of the system at CU. In addition these tests were performed at an ambient temperature of 68 oF

a much lower than our conditions, but this can be revised by curved coefficient provided by Capstone.

Set ambient temperature as T1 =68 oF=527.67

oR

[Eng. Unit]

T [°R]

h[BTU/lb]

T = 515.61 741.87 1420.47 1866.87 1580.67 1287.27

h = 125.998 177.6835 348.258 467.9991 390.5886 313.6657

pr = 1.27994 4.231709 45.37222 132.0248 68.16768 31.23338

Pressure ratio

1 Inlet temperature was calculated by adding 6.7oC to the ambient temperature. This

temperature rise is caused the generator being cooled by the inlet air.

T1 Compressor inlet temperature1 68

oF 527.67

oR

T2 Compressor outlet temperature 282.2 oF 741.87

oR

T3 combustion chamber inlet temperature 960.8 oF 1420.47

oR

T4 Turbine inlet temperature 1407.2 oF 1866.87

oR

T5 Turbine outlet temperature 1121 oF 1580.67

oR

T6 Recuperator outlet temperature 827.6 oF 1287.27

oR


89

Corresponding . Thus

In 55°F the back work ratio is

Set ambient temperature as T1=115 °F=574.67 °R

Pr1 = 1.7252

h1= 137.3808

Pr2=5* Pr1=8.6260

T2s = 906.2229

h2s = 217.7908

Set ambient temperature as T1=1600 °F=2059.67 °R

Pr4= 196.1293

h4 = 521.3867

Pr5s= 39.2259

h5s = 334.3819

In 115F the back work ratio is

The cycle efficiency with recuperator is


90


91

Table A.3 Microturbine CHP - Typical Performance Parameters


92

Capstone C30 = 1,290 (2007$/kW)

Capstone C65 = 1,280 (2007$/kW)

2007 Cost of C30 = 1,290 (2007$/kW) * 30(kW) = 38,700 (2007$)

2014 Cost of C30 = 47,230 (2014$)

2007 Cost of C65 = 1,280 (2007$/kW)*65(kW) = 83,200 (2007$/kW)

2014 Cost of C65 = 101,570 (2014$)


93

APPENDIX B - Runtime Studies

● Runtime Calculation for CNG

Runtime59 =

43.5412 20.0959 13.7498

Runtime115 =

41.6744 17.3643 12.2572

● Runtime Calculation for JP-8 at 95kw

clear

HHV_C30=435000; %btu/hr

HHV_C65=842000; %btu/hr

Hv_jp8=18413; %btu/lb

mass=1000; %lb

Runtime=(mass*Hv_jp8)/(HHV_C30+HHV_C65)

Runtime = 14.4190 [hrs]

● GT Calcs and Code

T=Runtime

P=Power Output 30kW-60kW-90kW

eta=Efficiency of GT

etab=Efficiency of Battery

LHV=Low heat value of fuel

m=mass of fuel

D=Diameter of the fuel tank

rho=Density

m(D)=rho*4/3*D^3

T(P)=P/(m*LHV*eta*etab)

plot(P,T)

2-D figure of

Runtime vs. Power vs. Temperature

When over 90 kw output ; The maximum output = 100kW for 140 minutes.


94

APPENDIX C - Fuel System Calculations

Reference Cost for 3000 Gallon Pillow Tank

http://www.baselineequipment.com/

Cost Model - Spherical CNG Tank (NOT USED IN PRELIMINARY DESIGN)

Description

For approximate the total cost of fuel tank, it is necessary to use two major variables with the cost model.

The first step is operating with the size model, which define the reference size as 300 gallons. And

then,based on cost approximated by size model and define the reference pressure as 2 Mpa(290 psi) to

solve the pressure model.

1. Size model

● Cost’=777.83 US dollar

2. Pressure model

● Cost=9500 US dollar

3. Mass of tank

● Mass of the spherical vessel M=3055.68lb

1. Size model

● Cr = 672.95; %Dollars

● S = 383.91; %gallon

● Sr = 300; %Ref Size gallon

● m = 0.6;

● Cost = Cr*(S/Sr)^m=777.83 US dollar

2. Pressure model

● m1=0.85

● Cr=777.83 US dollar

● P=5500 psi

● Pr=290 psi

● Cost=Cr*(P/Pr)^m1=9500 US dollar(after round-off)

3. Mass of tank

● Pressure difference from ambient 5500 psi

● Vmax=88683.8976 in^3

● Density=0.284 lb/in^3

● The maximum working stress is defined as 63800 psi

● Mass of the spherical vessel M=3055.68 lb

4. Mass of natural gas

● Density of natural gas at 5500 psi is 0.0083525441 lb/in^3.

● Mass of natural gas is 741 lb.


95

APPENDIX D - Other Battery System Specifications

Efficiency

Table D.1 The efficiency of different battery models.


Figure D.1 The efficiency curve


This Curve shows the Efficiency vs Load. The efficiency is different between different loads. To achieve

higher efficiency, load the battery to maximum.

Transformer

Table D.2 The Transformer information

(Ref: http://www.schneider-electric.com/products/us/en/53700-transformers/53720-low-voltage-

transformers/60303-drive-isolation-transformers/)

The operating voltage of the battery system and the gas turbine are different. From our research, we

decided to use two transformers. The transformer will be purchased separately but will be installed into

the battery system.

http://www.schneider-electric.com/products/us/en/53700-transformers/53720-low-voltage-transformers/60303-drive-isolation-transformers/

http://www.schneider-electric.com/products/us/en/53700-transformers/53720-low-voltage-transformers/60303-drive-isolation-transformers/


96

Battery Cell

Table D.3 The Battery Specifications


The UPS model uses VRLA battery. VRLA battery has a large capacity and do not need any

maintenance. What's more, It is very safe and will never explode or burn.

Cost Model

Table D.4 Current Cost Model Excluding Tax

Environment

Table D.5 The Environmental Information


Operation is quiet and temperature insensitive.


97

APPENDIX E - Safety System Calculation

Calculation for Safety/Fire Suppression System

The density in the cylinder is d=0.111 lb/ft^3

The volume of the packaging is V=20*8*8=1280 ft^3

When the ratio of the volume of Carbon Dioxide to the total volume is 0.35~ 0.5 , the fire will be put off,

we choose the coefficient k=0.5

(Source: CO2 fire extinguishing system calculations, Water Transportation Planning and Design Institute

of Heilongjiang, 2012)

According to the requirement that CO2 needs to be used 3 times.

The total mass of CO2 is m=3*k*density*volume=213.12 lb

Number of cylinder n=m/75=2.84

Therefore, we need 3 cylinders

Cost Model

The similar fire suppression is 1000 US dollar, Cr =1000 US dollar;

and the quantity of Carbon Dioxide is 154.32 lb, Sr = 154.32 lb;

The quantity of Carbon Dioxide in our system is 705 lb S =705 lb;

m = 0.6;

Therefore, the cost for the fire suppression system is 2488.06 US dollar.

Cost = Cr*(S/Sr)^m=2488.06 US dollar


98

APPENDIX F - Cost Model

Table F.1 Cost excluding tax (2014$)

Item Price

Gas Turbine C30 $ 47,230

Gas Turbine C65 $ 101,570

Fuel Bladder (3000 gallons) $ 4,145.47

Spherical fuel tank $ 9,500.00

Battery system $ 43,088.00

Suspension System C30 $ 5,000.00

Suspension System C65 $ 7,500.00

Safety System $ 2,488.06

Packaging unit $ 10,000.00

Warehouse storage cost $ 900.00 / month *36 months = $ 32,400

Manufacturing Cost $100,000


99

APPENDIX G - NOX emission analysis

Figure G.1 Ryan Firestone and Chris Marnay, 2005,

“Microturbine Economic Competitiveness:A Study of Two Potential Adopters”, LBNL-57985


100

APPENDIX H - Team members contact information

Design Team NOMAD - Contact Information

Name Phone Email Designation

Ben Sandoval (928)978-1860 [email protected] Team Lead

Jake Gunnoe (928)710-8915 [email protected] Project Manager

Tanvi Nidgalcar (480)463-0714 [email protected] Lead Engineer

Tianze Peng (480)619-1555 [email protected] Gas Turbine Systems Engineer

Shuyu Gong (480)432-2745 [email protected] Battery Systems Engineer

Guoyi Li (480)577-1756 [email protected] Fuel Systems Engineer

Danyang Yu (480)252-4327 [email protected] Safety Systems Engineer

mae - 446 energy systems design project - nomad€¦ · nomad power is a design group consisting of...

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