mechanical systems thesis proposal - penn state engineering ......mechanical, electrical, and...

Mechanical Systems Thesis Proposal: Calvert Memorial Hospital

Prince Frederick, MD

Holly Mawritz

Senior Thesis Project Proposal

Penn State University Department of Architectural Engineering

Mechanical Emphasis Faculty Consultant: Dr. Jim Freihaut

12-10-04

Mechanical Systems Thesis Proposal Calvert Memorial Hospital


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Table of Contents:

Executive Summary 2

Background: Existing Mechanical Systems 3

Air Systems 3

AHU-3 3

AHU-4 3,4

Water Systems 4

Heat Pumps 4

Heat Pump Cooling Tower 4

Chilled Water Plant 5

Boiler Plant 5

Areas of Focus for Better Design Solutions 6,7

Proposed Design Solutions 8

Removal of Patient Room Heat Pumps 8

The Desiccant Wheel 9,10

Ultraviolet Germicidal Irradiation 10,11

Design Solution Methods 12

Removal of Patient Room Heat Pumps 12

The Desiccant Wheel 12,13

Ultraviolet Germicidal Irradiation 13

Breadth Ideas 14

Project Methods 15

Preliminary Research Resources 16

Calendar Schedule of Tasks 17-20



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Executive Summary:

This report is based on the collaboration of previously written research papers in

preparation for the redesign of the mechanical systems of Calvert Memorial Hospital in

Prince Frederick, Maryland. This proposal will assimilate an analysis of the hospital’s

mechanical, electrical, and structural systems. This project will be finished and presented

in the Penn State University Architectural Engineering Senior Thesis Presentations at the

end of the spring 2005 semester.

The existing mechanical system is explained in basic detail to represent the current

operation of the equipment. The objectives to the mechanical design rely heavily on

indoor air quality and infection control. These issues will increase the building’s first

costs, but eventually the benefits of the proposed systems in this report will eventually

overshadow the first cost expenses. The use of UVGI (Ultraviolet Germicidal

Irradiation) systems for infection control in critical spaces and exhaust ducts will

decrease insurance costs over time. The addition of desiccant wheels to the system

cooling configuration will result in a reduction of some of the mechanical equipment

sizes, which will also lower mechanical equipment costs. Smaller mechanical equipment

creates a reduction in energy used. All of these topics will be discussed in further detain

in this proposal.

The scope of this proposal is to fully explain the mechanical redesign and include areas

of breadth topics such as the electrical and structural systems. The impact of these

proposed ideas will be evaluated in this thesis study.

Lastly, there will be an estimated schedule that gives an outline of the research processes

for this proposal. This timeline will begin in December 2004 with the initial thesis

proposal and end in April 2005 when the Architectural Engineering Senior Thesis

Presentations will begin.



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Background: Existing Mechanical Systems:

Calvert Memorial Hospital contains a plethora of different mechanical systems. Due to

the complexity and size of the hospital, the areas of focus will include the 2nd – 5th floor

patient towers. Below is a summary of the mechanical systems serving these areas of the

hospital. Many of these systems will be replaced or renovated in the proposal section of

this report.

Air Systems:

AHU-3

AHU-3 is a commercial grade, constant volume air handling unit which was

originally installed in 1977. The air handling unit resides in the second floor

mechanical penthouse. The areas served by this unit are the Intensive Care areas

and Isolation rooms on the second and third floors. The unit utilizes a percentage

of outside air and has a rating of 4000 cfm at 3.0 inches of static pressure. The

unit is in poor condition and lacks final filters. Due to these unsatisfactory

conditions, the hospital has begun planning for expansion of the areas served by

this air handling unit. The new air handler, AHU-PT-1 will replace the original

AHU-3 and will remain in the second floor mechanical room and serve the same

areas including the expanded areas. The planned capacity for the new air handler

will be approximately 50,000 cfm.

AHU-4

AHU-4 is a commercial grade, constant volume air handling unit which was also

installed in 1977. This unit is located in the second floor mechanical penthouse

and currently serves the first, second, and third floor corridors. This unit utilizes a

percent of outside air and is rated for 11,000 cfm at 3.5 inches of static pressure.

This unit is also in poor condition, and is also lacking the appropriate final filters.

The hospital renovation plans are to remove the existing AHU-4 and using the

new AHU-PT-1 as the unit to serve the new second floor patient expansion and



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existing second and third floor patient towers. In addition, AHU-PT-1 will serve

the Post-Partum on the first floor that is currently supplied by heat pumps.

Water Systems:

Heat Pumps

Water source heat pumps are used to serve numerous portions of the hospital but

serve a majority of the rooms involved in the hospital patient tower (floors two

through five). The patient tower’s heat pump systems serve the second and third

floor patient rooms and the entire fourth and fifth floors of the hospital. The heat

pumps can either cool the air by rejecting heat or heat the air by collecting heat

from the central condenser water loop. The heat pumps are of varying ages and

capacities. Removing the heat pumps and replacing them with an all-air system

configuration has been discussed, but currently no new designs have been

developed.

Heat Pump Cooling Tower

Approximately one-third of Calvert Memorial Hospital is served by water source

heat pumps. These heat pumps reject to two cooling towers: Cooling Tower

No.1 and Cooling Tower No.4. Cooling Tower No.1 is a 378 ton forced-draft

cooling tower was installed in 1977. Cooling Tower No.4 is an induced-draft

cooling tower of unknown capacity. Cooling Tower No. 1 serves the basement,

first, second, and third floor heat pumps while Cooling Tower No.4 serves the

fourth and fifth floor heat pumps. Both of the cooling towers are in poor

condition. For winter operation, Cooling Tower No. 4 utilizes an electric boiler

and a plate and frame heat exchanger for adding required heat to the loop. Also,

the louvers required for optimal winter operation of Cooling Tower No. 1 are

missing. The hospital already has plans of removing these heat pumps, but not for

another 15-20 years.



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Chilled Water Plant

The existing chilled water plant consists of three electric centrifugal chillers.

These chillers are located in the basement mechanical room. Chiller No. 1 has a

rated capacity of 110 tons and was installed in 1996. Chiller No. 2 and Chiller

No. 3 each have a rated capacity of 260 tons and were both installed in 1998.

The chiller plant’s total capacity is 630 tons. Chiller No.1 uses R-22 refrigerant

while Chiller No. 2 and Chiller No. 3 use R-134A refrigerant. The chillers

operate with an entering chilled water temperature of 55oF and a leaving chilled

water temperature of 45oF. All of the chillers are in good condition.

Boiler Plant

The main boiler plant is located in the basement of the hospital. The plant

contains two hot water boilers, each having a rated capacity of 5021 MBH. They

are both forced-draft, gas-fired, fire tube type and are each equipped with a

Cyclonetic burner. They were installed in 1996 are in excellent condition.



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Areas of Focus for Better Design Solutions:

The main emphasis of the mechanical redesign of Calvert Memorial Hospital is to

achieve a more desirable performance of the mechanical systems based on the assignment

requirements. The topics proposed in this redesign report in no way imply that the

current mechanical, electrical, or structural systems of Calvert Memorial Hospital are

dangerous or in error.

One of the primary focuses of health care facilities are indoor air quality, and infection

and disaster control. Through time, these issues have become more critically studied.

Hospitals must follow important design parameters to ensure that the occupants are not

exposed to any harmful contaminants in the air.

A new air distribution system must be designed for the patient tower of Calvert Memorial

Hospital in order to maintain a healthier living environment for the hospital occupants.

The patient tower consists of the second, third, fourth, and fifth floors. The majority of

the spaces on each floor consist of patient rooms that are all conditioned by water-source

heat pumps. The heat pumps contain condensate drip pans that collect moisture

condensing on the evaporator coil in the air conditioning system. These drip pans allow

molds and other particles to grow, eventually exposing bacteria and mold spores to the

breathable air. It is proposed that all of the hospital’s heat pumps located in patient

rooms be removed and replaced with all overhead air systems.

The existing cooling towers serving the heat pumps are presently in poor shape. A new

single cooling tower is suggested to replace the other cooling tower configuration. The

cooling tower capacity will be further calculated once the heat pumps are removed and

the new room loads are calculated. The Chilled Water and Boiler Plants, will most likely

need replacements and modification due to the new system configurations.

In continuing the quest for a healthier indoor air environment, humidity control must also

be taken into consideration. Humid air creates the possibility for molds and bacteria to



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grow, allowing infections to possibly spread from person to person. A drier air

environment is needed; therefore a Desiccant Wheel will be implemented to air system.

Along with the desiccant wheel configuration, UVGI (Ultraviolet Germicidal Irradiation)

systems will be installed in the critical spaces and exhaust ducts.



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Proposed Design Solutions:

The following section describes a summary of the different design solutions to the

mechanical systems being evaluated. In the solution for administering the proper indoor

air quality and infection control of the hospital, the following ideas will be implemented

to the building design: Removal of all patient room heat pumps, use of desiccant wheels

in the building cooling system, and the installation of Ultraviolet Germicidal Irradiation

in the critical care areas and exhaust ducts.

Removal of Patient Room Heat Pumps

The heat pumps serving the patient tower patient rooms contain bacteria and

molds in the condensate drip pans. A drip pan is shaped to collect moisture

condensing on an evaporator coil in an air conditioning of refrigeration system.

Inadequate drainage of ductwork in terminal humidifiers can lead to potential

downstream condensation, which may cause microbial growth in air distribution

systems. These contaminants are emitted into the breathable air space, creating

unsatisfactory breathable air quantities. To eliminate this problem, the heat

pumps will all be removed and replaced with all overhead air systems. By

removing the heat pumps the amount of equipment that needs to be maintained

will be minimized and the system will become more versatile for future

modifications.

The overhead air system replacing the heat pumps will be a variable-air-volume

configuration. There will be two air handling units provided to serve these

spaces. The first of the two units, AHU-PT-1 (old AHU-3) is currently serving

areas of the second and third floor spaces. The second and third floor patient

rooms that were originally conditioned by the heat pumps will be added to the

existing air handling unit, AHU-PT-1. As described in the Existing Mechanical

Systems portion on the proposal, the AHU-PT-1 is located in the second floor

mechanical room. The entire fourth and fifth floors will be served by a new air

handling unit that will be located on fifth floor patient tower roof.



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The Desiccant Wheel

In the cooling system of the building, it is proposed that desiccant wheels are

installed to help control the hospital’s humidity levels. Dehumidification is the

main focus of the desiccant cooling system. It reduces the building’s latent load

by removing excess moisture from the air. Moisture reduction stops or slows

bacteria from growing or traveling through the air. The reduction of the latent

load also decreases the size of the chiller. The air temperature of the sensible load

will be dry but very hot, so sensible coolers such as rotary heat exchangers,

evaporative coolers or coiling coils will be installed and sized accordingly.

The desiccant used can either be solid or liquid. In this analysis a liquid lithium

bromide spray solution will be used. The liquid desiccants work based-on the

principle of chemical absorption of water vapor from the air to be conditioned.

The humid air will pass through the lithium bromide solution spray becoming

dehumidified. This occurs because the desiccant solution has a lower water vapor

pressure than the air passing through it. Over time, the desiccant solution will

become diluted due to the water extracted from the air, so it must be fed to a

regenerator. The regenerator will then heat the lithium bromide, causing moisture

to transfer to the desiccant. The heated desiccant is then sprayed into the air

stream of the outdoor air and the moisture is released and exhausted to the

outside. The regenerated desiccant is then cooled and reused.

The benefits of using the lithium bromide solutions vary.. The performance of the

solution depends on the air temperature. Lower temperature are desired, therefore

it is best to run the solution through a chiller. Also, the lithium bromide kills

bacteria on contact so the liquid desiccant has the ability to deliver biologically

uncontaminated air to the surroundings. There are also no wet surfaces to

promote bacterial growth, so this system is more beneficial than using cooling

coils. If there were any doubts or worries about the spread of the lithium bromide

solution to the surrounding breathable air, the UVGI (Ultraviolet Germicidal



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Irradiation) in the exhaust ducts would kill off any of the proposed particles.

These UVGI systems will be further discussed in the following section of this

proposal.

Ultraviolet Germicidal Irradiation

One of the major aspects of contamination control is ventilation. In Calvert

Memorial Hospital an alternative measure will be taken through the use of UVGI

(Ultraviolet Germicidal Irradiation). Two kinds UVGI will be used to control

contamination; one alternative will be Ultraviolet placed in the exhaust air stream

and the other will be Ultraviolet lamp fixtures placed in the critical space areas.

By adding these two UVGI systems, there will be a significant initial expense to

the hospital. But the systems will create a savings on the hospital’s insurance

issues due to the enhanced infection control configurations. The system will

reduce energy costs due to the decreased outdoor air intake.

Determining the amount of equivalent air flow received after installation of the

UV systems and the kill rate of UVGI to that which is realized by adding

ventilation for proper contamination control must be evaluated. The added

ventilation dilutes the contamination as if the bacteria have been killed. The

equivalent air flow for the addition of UV is found by comparing the added

ventilation to the actual kill rate from UV.

Duct irradiation will be used in the exhaust air stream. The duct irradiation

sterilizes the air which flows through a portion of the exhaust air stream. In order

to maintain efficient kill results, duct sizes will need to be sized as large as

possible without being too much of a burden on cost. The reason for the larger

ducts is to slow down the velocity of the air moving through the UV killing zone.

The longer the contaminant particles remain in the UV killing zone, the more

particles will be killed. By slowing down the air velocity of the duct, more

harmful particles will be killed.



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Upper room irradiation will be implemented in the critical areas of the hospital

such as the patient rooms, intensive care units, and operating rooms. The Upper

Room Irradiation involves UVGI lamp fixtures that will be suspended or mounted

on the room’s ceiling or walls. The bottom portion of the light will be shielded to

direct all radiation upward and prevent the lamps from coming in contact with the

direct sight of the occupants. In analyzing the upper room irradiation procedure,

the following factors will be considered: distance from the source, humidity

levels, dust in the air, height of the ceiling, and the mixing factors occurring in the

rooms. These different factors will determine the effectiveness of the upper room

radiation.



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Design Solution Methods:

The following section describes a brief explanation of the different methods that will be

used to redesign the mechanical systems being evaluated. The design solution methods

will decipher the proper indoor air quality and infection control of the hospital.

ASHRAE Standard 62 will be used in evaluating the clean air procedures. The following

methods will be explained: Removal of all patient room heat pumps, the use of desiccant

wheels in the building cooling system, and the installation of Ultraviolet Germicidal

Irradiation in the critical care areas and exhaust ducts.

Removal of Patient Room Heat Pumps

The heat pumps will all be removed and replaced with overhead air systems.

Loads will be calculated for the second, third, fourth, and fifth floor patient tower

rooms by the HAP (Hourly Analysis Program) to determine the appropriate air

distribution to each space. Once these airflows are determined, the air handling

units can be chosen. The existing unit located in the second floor mechanical

room (first floor roof) should be able to handle the additional load requirements

for the second and third floor patient rooms. An appropriate air handling unit will

then be selected for the fourth and fifth floors as well. The first and fifth floor

roof structural systems will be evaluated to determine if the structures will

withstand the weight of the new equipment.

The Desiccant Wheel

Dehumidification is the main focus of the desiccant cooling system. An analysis

of the reduction of the latent load will be administered, thus changing the

capacities of some of the mechanical equipment. Examples of the changed

equipment are: heat exchangers, evaporative coolers, cooling coils, and the

chiller. The loads determined from the HAP analysis will assist in determining a

total loads for rooms in question.



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The liquid lithium bromide spray that will be desiccant material of the cooling

system will then be evaluated in terms of effectiveness, cost and other benefits of

the spray solution. A detailed analysis explaining the desiccant wheel cooling

system configuration will also be implemented into the report. From the HAP

loads as well as the desired operating temperature of the desiccant fluid, a new

chiller will be chosen.

Ultraviolet Germicidal Irradiation

By running a new load analysis on the hospital patient rooms, a new ventilation

requirement will be established. Since contamination control is heavily related to

ventilation in buildings, this will decipher the usages of UVI (Ultraviolet

Germicidal Irradiation) that will be employed in the hospital. The two kinds

UVGI will be used to control contamination; one alternative will be Ultraviolet

placed in the exhaust air stream the other will be Ultraviolet fixtures placed in the

critical space areas. The system ductwork, both supply and exhaust, will be sized

from the load. The equivalent air flow for the addition of UV will be evaluated

by comparing the added ventilation to the actual kill rate from UV and then

setting up the proper equations. This will also affect the sizes of the ducts for the

duct irradiation procedure because the larger the duct size, the slower the air flow.

The slower the air flow is, the more time the lithium bromide spray has to collect

harmful particles to be killed.

Upper room irradiation will be implemented in the critical areas of the hospital

such as the patient rooms, intensive care units, and operating rooms. Due to the

UVGI lamps being wall or ceiling mounted in the rooms, there will be an intense

analysis of distances from the lamp source to the room occupant. It is important

that the radiation emitted from the UVGI lamps does not come in direct site with

the occupants. Humidity levels, dust in the air, height of the ceiling, and the

mixing factors occurring in the rooms will also be evaluated.



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Breadth Ideas:

The mechanical redesign of Calvert Memorial Hospital will impact the other building

systems in the construction and operational aspects. The breadth areas under analysis for

this proposal are: electrical and structural.

The complicated mechanical redesign requires there to be advanced electrical changes to

the hospital’s electrical systems. New UVGI (Ultraviolet Germicidal Irradiation) lamps,

also known as upper room radiation, will be installed in the existing patient rooms and

critical areas to help increase the building indoor air quality. New electrical loads will be

evaluated for each space thus changing the system feeders, panel boards, and over current

protection devices.

The structural system of the hospital will be evaluated at the first floor roof and at the

fifth floor roof. The existing air handling unit located in the second floor mechanical

room (on the first floor roof) is designated as AHU-PT-1. This portion of the first floor

roof will be analyzed to determine if the new AHU-PT-1 load will affect the existing

structural members. The second and new air handling unit being evaluated will be placed

on the roof of the fifth floor of the building. Here, the framing member sizes will be

analyzed and compared to the existing structure to determine if there is a necessary

increase in load.



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Project Methods:

The research and modeling of the previously proposed design schemes will be

accomplished by using various design tools. The redesign of Calvert Memorial Hospital

will begin with the mechanical systems and continue on with the breadth topics; the

electrical and structural systems.

The first area of analysis will be the new hospital loads. By researching the patient room

and intensive care treatment areas, important data will be accumulated for the load

calculation process. Information on the types of equipment, square footages, and

occupants will be acquired by contacting Calvert Memorial Hospital. Information may

also be attained from Leach Wallace Associates, who have already done previous work

on the hospital. Carrier’s Hourly Analysis Program will them be used to model the

proposed new ventilation and air systems. With these calculations, research from the

UVGI duct systems and desiccant cooling configurations will be evaluated.

After the mechanical depth has been established, the breadth work on the electrical

system will begin. The electrical system will change due to the installation of UVGI

lamps located in the critical patient areas. A lighting compliance will be administered

using the ASHRAE Standard 90.1-2001 to ensure that the proper lighting is being

delivered to each of the spaces. The 2002 National Electric Code will be utilized to make

alterations to the electrical designs.

The addition of air handling units and energy recovery equipment will prompt the

structural analysis. The STAAD program will be used to determine if the loads of the

new equipment meet the structure requirement. These results will be compared to the

existing conditions and will be altered if needed.



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Preliminary Research Resources:

Bahnfleth, W. P., PhD, PE, W. J. Kowalkski,. PhD, PE. “Airborne-Microbe Filtration in

Indoor Environments.” HPAC Engineering. Jan. 2002: pp. 57-69.

Finkelstein, Hal. Contamination Control, Ventilation: A Guide to Engineering, Design,

& Operations. Washington, D.C.: The National Resource Center, 1998.

Hansen, Wayne, PE, REA, CEM. A Guide to Managing Indoor Air Quality in Health

Care Organizations. Oakbrook Terrace: Joint Commissions on Accreditation of

Healthcare Organizations, 1997.

Memarzadeh, Farhad. Handbook on Assessing the Efficacy of Ultraviolet Germicidal

Irradiation and Ventilation in Removing Mycobacterium Tuberculosis. Bethesda:

National Institutes of Health, 2000.

“Natural Gas Desiccant Systems.” Uniongas: A Duke Energy Company. Union Gas

Limited 2000-2004. 7 Dec. 2004 <http://www.uniongas.com/dehumid/systems.asp>

Streifel, Andrew J., MPH, REHS. “Health-Care IAQ: Guidance for Infection Control.”

HPAC Heating/Piping/Air-Conditioning Engineering. Oct. 2000: pp. 28-36.



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Calendar Schedule of Tasks:



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mechanical systems thesis proposal - penn state engineering ......mechanical, electrical, and...

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