computer intergrated heat exchanger laboratory apparatus

Group Number: UGP2016-14

Development of a computer integrated heat

exchanger test apparatus for the thermodynamics

laboratory of the Department FINAL REPORT

Submitted to the

DEPARTMENT OF MECHANICAL & MANUFACTURING ENGINEERING

Of the

FACULTY OF ENGINEERING

in partial fulfillment of the requirements for the

Degree of Bachelor of Science of Engineering

By MAITIPE P.C. (EG/2012/1992)

RAJASINGHE R.A.D.P.M. (EG/2012/2044)

WIMUKTHI K.A.H. (EG/2012/2123)

Approved:

DEPARTMENT OF MECHANICAL & MANUFACTURING ENGINEERING

FACULTY OF ENGINEERING

UNIVERSITY OF RUHUNA

…………………………………….

Dr. Chaminda Karunasena (Supervisor)

…………………………………….

Ms. Thamali Jayawickrama (Co-Supervisor

…………………………………….

Mrs. Kalpani Pathmasiri (Co-Supervisor)

ii

ABSTRACT

Computer integrated heat exchanger unit is most useful equipment for testing the

various kind of heat exchangers in the laboratory. Considering mechanical and manufacturing

department’s thermodynamic laboratory it still has not this kind of computer integrate heat

exchanger test apparatus. Because of its normal market price is very high around six million

rupees. The overall objective of the project is to development of a computer integrated heat

exchanger test apparatus for the thermodynamics laboratory of the Mechanical and

Manufacturing Department. This unit can use for find the heat removal rate for each material,

overall heat transfer coefficient and heat rejection for different materials. Heat exchangers are

most important parts of the machinery in the industry such as automobiles, chillers and oil

coolers.

iii

TABLE OF CONTENTS

LIST OF FIGURES .............................................................................................................. v

LIST OF TABLES ............................................................................................................... vi

INTRODUCTION ........................................................................................... 1

1.1 Background of the project ...................................................................................... 1

1.2 Background of Problem ......................................................................................... 2

1.3 Aims and objectives ............................................................................................... 2

1.4 Scope of project ..................................................................................................... 2

LITERATURE REVIEW ................................................................................ 4

2.1 Function of heat exchanger .................................................................................... 4

2.2 Theory ................................................................................................................... 5

2.2.1 Conduction ........................................................................................................ 5

2.2.2 Convection......................................................................................................... 5

2.2.3 Radiation ........................................................................................................... 6

2.2.4 Heat Exchangers ................................................................................................ 6

2.2.5 Counter Flow ..................................................................................................... 6

2.2.6 Parallel flow ...................................................................................................... 7

2.2.7 Enthalpy Balances in Heat Exchangers .............................................................. 8

2.2.8 Average Temperature of Fluid Stream................................................................ 9

2.2.9 Overall Heat Transfer Coefficient .................................................................... 10

....................................................................................................................... 12

ONGOING WORK AND DESIGN CALCULATIONS ...................................................... 12

3.1 Computer aided design of apparatus .................................................................... 12

3.2 Design calculations .............................................................................................. 13

3.2.1 Windshield pump ............................................................................................. 13

3.3 Detailed design .................................................................................................... 14

3.4 Calculations ......................................................................................................... 34

iv

3.5 Future works ........................................................................................................ 35

3.6 Time Line ............................................................................................................ 36

BIBLIOGRAPHY ............................................................................................................... 37

APPENDIX ........................................................................................................................ 38

v

LIST OF FIGURES

Figure 1: Counter flow heat exchanger ...........................................................................................................7

Figure 2: Parallel flow heat exchanger............................................................................................................8

Figure 3. CAD design of heat exchanger apparatus ...................................................................................... 12

Figure 4. Windshield washer pump .............................................................................................................. 13

Figure 5. Motor controller connect with Arduino AT-mega .......................................................................... 14

Figure 6. Test apparatus for pump calibration ............................................................................................... 14

Figure 7: Side view of Heat exchanger test apparatus ................................................................................... 15

Figure 8: Top view of heat exchanger........................................................................................................... 16

Figure 9: fabricated model ........................................................................................................................... 18

Figure 10: double pipe heat exchanger ......................................................................................................... 18

Figure 11: Hot water tank with heater........................................................................................................... 19

Figure 12: Cold water tank with pump ......................................................................................................... 19

Figure 13: wind shield pump ........................................................................................................................ 20

Figure 14: Temperature sensor ..................................................................................................................... 20

Figure 15: Motor controller .......................................................................................................................... 21

Figure 16: arduino mega .............................................................................................................................. 21

Figure 17: 5 channel selector switch ............................................................................................................. 22

Figure 18: Electrical layout .......................................................................................................................... 22

Figure 19: labview program ......................................................................................................................... 24

Figure 20: Lab view interface ....................................................................................................................... 25

Figure 21: Simulation model ........................................................................................................................ 25

Figure 22: Parallel flow ................................................................................................................................ 34

Figure 23: time Line ..................................................................................................................................... 36

vi

LIST OF TABLES

Table 1. Results of water pump calibration ................................................................................................... 13

Table 2: Conceptual design .......................................................................................................................... 17

1

INTRODUCTION

1.1 Background of the project

Exchangers are easily one of the most important and widely used pieces of process

equipment found in industrial sites. Regardless of the particular industry in question, it will

likely require some type of temperature regulation. Exchangers may be used for either

heating or cooling, however, in the industrial sector, particularly within plants and

refineries, they are overwhelmingly used for cooling. Heat exchangers have a very broad

range of industrial applications. They are used as components of air conditioning and

cooling systems or of heating systems. Different types of heat exchangers work in different

ways, that practical unit has double pipe heat exchangers use different flow arrangements,

equipment, and design feature

The double-pipe heat exchanger is one of the simplest types of heat exchangers. It is

called a double-pipe exchanger because one fluid flows inside a pipe and the other fluid

flows between that pipe and another pipe that surrounds the first. This is a concentric tube

construction. Flow in a double-pipe heat exchanger can be co-current or counter-current.

There are two flow configurations: co-current is when the flow of the two streams is in the

same direction, counter current is when the flow of the streams is in opposite directions.

Heat Exchangers are generally classified by one of the following four metrics,

1. The nature of the heat exchange process

2. The physical state of the fluids

3. The heat exchanger’s flow arrangement

4. The design and construction of the heat exchanger

2

1.2 Background of Problem

A range of small-scale heat exchangers, designed to illustrate the principles and

techniques of indirect heat transfer between fluid streams. Different types of heat

exchanger can be mounted on a common bench-top service unit. Small scale versions of

commonly used industrial heat exchangers are available (including plate, tubular and ‘shell

and tube’) for analysis and comparison. The equipment is controlled by a user supplied

personal computer, which serves as the operator interface. Full data logging, control and

educational software is supplied with the equipment. In addition, the equipment has been

fitted with failsafe systems, including a watchdog circuit, which allows for safe operation

from a remote computer.

1.3 Aims and objectives

The overall objective of the project is to development of a computer integrated heat

exchanger test apparatus for the thermodynamics laboratory of the Mechanical and

Manufacturing Department.

- Test different type of heat exchangers at one unit.

- The market cost of this type of apparatus is expensive. But. Hope to made it in low

cost with same functions.

1.4 Scope of project

Computer integrate heat exchanger laboratory apparatus is fabricated to thermodynamic

laboratory for test various kind of heat exchange parameters and compare different type of

heat exchangers performance.

The following degrees of freedom can be varied in this experiment:

Hot water feed temperature and flow rate

Cold water feed temperature and flow rate

Heat exchanger type (tubular, shell & tube, or plate)

Flow direction (parallel or counter-flow)

Heat exchanger configurations; parallel vs. counter-current flow

Logarithmic Mean Temperature Difference (LMTD) and Effectiveness-NTU

methods for analysis of heat exchangers

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We hope to investigate effects of these variables on the following performance indicators:

Return temperatures and of the hot and cold water

Heat flow rate (𝑞)

Overall heat transfer coefficient (𝑈)

The equipment is controlled by a user supplied personal computer, which serves as the

operator’s interface. Full data logging, controlling software is communicating with the

equipment. The “Arduino” and “LabVIEW” software were used as a major controlling

software.

Arduino is an open-source hardware, open-source software, and microcontroller-

based kits for building digital devices and interactive objects that can sense and

control physical devices.

LabVIEW (Laboratory Virtual Instrument Engineering Workbench) is a system-

design platform and development environment for a visual programming language.

In this project we will fabricate a lab-scale model and simulator of a computer integrated

heat exchanger test apparatus.

4

LITERATURE REVIEW

Heat exchanger is a device, such as an automobile radiator, used to transfer heat from a fluid on one

side of a barrier to a fluid on the other side without bringing the fluid into direct contact. Usually,

this barrier is made from metal which has good thermal conductivity in order to transfer heat

effectively from one fluid to another fluid. Besides that, heat exchanger can be defined as any of

several devices that transfer heat from a hot to a cold fluid. In engineering practical, generally, the

hot fluid is needed to cool by the cold fluid. For example, the hot vapor is needed to be cool by

water in condenser practical. Moreover, heat exchanger is defined as a device used to exchange heat

from one medium to another often through metal walls, usually to extract heat from a medium

flowing between two surfaces. In automotive practice, radiator is used as heat exchanger to cool

hot water from engine by air surrounding same like intercooler which used as heat exchanger to

cool hot air for engine intake manifold by Air surrounding. Usually, this device is made from

aluminum since it is lightweight and good thermal conductivity.

2.1 Function of heat exchanger

Heat exchanger is a special equipment type because when heat exchanger is directly fired by a

combustion process, it becomes furnace, boiler, heater, tube-still heater and engine. Vice versa,

when heat exchanger makes a change in phase in one of flowing fluid such as condensation of steam

to water, it becomes a chiller, evaporator, sublimate, distillation-column reboiler, still, condenser

or cooler-condenser. Heat exchanger may be designed for chemical reactions or energy-generation

processes which become an integral part of reaction system such as a nuclear reactor, catalytic

reactor or polymer. Normally, heat exchanger is used only for the transfer and useful elimination or

recovery of heat without changed in phase. The fluids on either side of the barrier usually liquids

but they can be gasses such as steam, air and hydrocarbon vapor or can be liquid metals such as

sodium or mercury. In some application, heat exchanger fluids may use fused salts [2].

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2.2 Theory

The process of heat exchange between two fluids that are at different temperatures and separated

by a solid wall occurs in many engineering applications. The device used to implement this

exchange is called a heat exchanger, and specific applications may be found in space heating and

air-conditioning, power production, waste heat recovery and chemical processing. The flow of heat

from a fluid through a solid wall to another fluid is often encountered in chemical engineering

practice. The heat transferred may be latent heat accompanying phase changes such as condensation

or vaporization, or it may be sensible heat coming from increasing or decreasing the temperature of

a fluid without phase change. Heat transfer is the movement of energy due to a temperature

difference. There are three physical mechanisms of heat transfer; conduction, convection, radiation.

All three modes may occur simultaneously in problems of practical importance.

2.2.1 Conduction

Heat conduction is the transfer of heat from one part of a body to another part of the same body or

from one body to another body in physical contact with it, without appreciable displacement of the

particles of the body. Energy transfer by conduction is accomplished in two ways. The first

mechanism is that of molecular interaction, in which the greater motion of a molecule at a higher

energy level imparts energy to adjacent molecules at lower energy levels. This type of transfer is

present, to some degree, in all systems in which a temperature gradient exists and in which

molecules of a solid, liquid, or gas are present. The second mechanism of conduction heat transfer

is by free electrons. The free-electron mechanism is significant primarily in pure metallic

Solids: the concentration of free electrons varies considerably for alloys and becomes very low for

nonmetallic solids. The distinguishing feature of conduction is that it takes place within the

boundaries of a body, or across the boundary of a body into another body placed in contact with the

first, without an appreciable displacement of the matter comprising the body.

2.2.2 Convection

Heat transfer by convection occurs in a fluid by the mixing of one portion of the fluid with another

portion due to gross movements of the mass of fluid. The actual process of energy transfer from

one fluid particle or molecule to another is still one of conduction, but the energy may be transported

from one point in space to another by the displacement of the fluid itself. Convection can be further

subdivided into free convection and forced convection. If the fluid is made to flow by an external

agent such as a fan or pump, the process is called forced convection. If the fluid motion is caused

6

by density differences which are created by the temperature differences existing in the fluid mass,

the process is termed free convection or natural convection. The motion of the water molecules in

a pan heated on a stove is an example of a free convection process. The important heat transfer

problems of condensing and boiling are also examples of convection, involving the additional

complication of a latent heat exchange. It is virtually impossible to observe pure heat conduction in

a fluid because as soon as a temperature difference is imposed on a fluid, natural convection currents

will occur due to the resulting density differences.

2.2.3 Radiation

Thermal radiation describes the electromagnetic radiation that is emitted at the surface of a body

which has been thermally excited. This electromagnetic radiation is emitted in all directions and

when it strikes another body part may be reflected part may be transmitted and part may be

absorbed. Thus heat may pass from one body to another without the need of a medium of transport

between them. In some instances there may be a separating medium, such as air which is unaffected

by this passage of energy. The heat of the sun is the most obvious example of thermal radiation.

2.2.4 Heat Exchangers

Heat exchangers are typically classified according to flow arrangement and type of construction. In

the first classification flow can be count flow or parallel Heat exchangers can also be classified

based on their configuration as double pipe and shell & tube heat exchangers. Double pipe is the

Simplest form of heat exchanger and consists of two concentric tubes carrying the hot and Cold

fluids. Heat is transferred to from one fluid in the inner tube from to the other fluid in the

Outer annulus across the metal tube wall that separates the two fluids.

2.2.5 Counter Flow

In the countercurrent flow heat exchangers, the fluids enter at opposite ends, flow in opposite

Directions, and leave at opposite ends. The temperatures are denoted as follows:

T1: Temperature of entering hot fluid, °C

T2: Temperature of mid-position hot fluid, °C

T3: Temperature of leaving hot fluid, °C

T4: Temperature of entering cold fluid, °C

T5: Temperature of mid-position cold fluid, °C

T6: Temperature of leaving cold fluid, °C

7

Distance along the heat exchanger

The approaches are

𝑇1 − 𝑇6 = Δ𝑇1

𝑇3 − 𝑇4 = Δ𝑇2

2.2.6 Parallel flow

In the parallel flow heat exchanger, the hot and cold fluids enter at the same end, flow in the same

direction, and leave at the same end. The temperature practices across the tube length are shown in the

below figure

Figure 1: counter flow heat exchanger

8

The approaches are,

𝑇1 − 𝑇6 = Δ𝑇1

𝑇3 − 𝑇4 = Δ𝑇2

2.2.7 Enthalpy Balances in Heat Exchangers

To design or predict the performance of a heat exchanger, it is essential to determine the heat lost

to the surrounding for the analyzed configuration. A parameter can be defined to quantify the

percentage of losses or gains. Such a parameter may readily be obtained by applying overall energy

balances for hot and cold fluids. In heat exchangers there is no shaft work and mechanical potential

and mechanical kinetic energies are small in comparison with the other terms in the energy balance

equation. If Qe is the heat power emitted from hot fluid, while Qa is the heat power absorbed by

cold fluid, and also if constant specific heats are assumed

𝑄𝑒 = �̇�ℎ(ℎ,𝑖−ℎ,𝑜) = �̇�ℎ𝐶𝑝ℎ(𝑇ℎ,𝑖−𝑇ℎ,𝑜)

𝑄𝑎 = �̇�𝑐(ℎ𝑐,𝑖−ℎ𝑐,𝑜) = �̇�𝑐𝐶𝑝𝑐(𝑇𝑐,𝑖−𝑇𝑐,𝑜)

Figure 2: parallel flow heat exchanger

9

Where,

𝑚 ̇ℎ, �̇�𝑐 : mass flow rate of hot and cold fluid, respectively.

ℎ, 𝑖, ℎ, : inlet and outlet enthalpies of hot fluid, respectively.

ℎ𝑐, 𝑖, ℎ𝑐, : inlet and outlet enthalpies of cold fluid, respectively.

𝑇ℎ,, 𝑇ℎ,𝑜 : inlet and outlet temperatures of hot fluid, respectively.

𝑇ℎ,, 𝑇ℎ,𝑜 : inlet and outlet temperatures of cold fluid, respectively.

𝐶𝑝ℎ, 𝐶𝑝 : specific heats of hot and cold fluid, respectively.

𝐻𝑒𝑎𝑡 𝑝𝑜𝑤𝑒𝑟 𝑔𝑎𝑖𝑛 𝑜𝑟 𝑙𝑜𝑠𝑠=|𝑄𝑒|−|𝑄𝑎|

Percentage P of losses or gains is,

𝑃=|𝑄𝑎||𝑄𝑒|×100

If the heat exchanger is well insulated, Qe and Qa should be equal. Then, the heat lost by the hot

fluid is gained by the cold fluid Qa = -Qe

In practice these differ due to heat losses or gains to/from the environment. If the average cold fluid

temperature is above the ambient air temperature then heat will be lost to the surroundings resulting

In P < 100%. If the average cold fluid temperature is below the ambient temperature, heat will be

gained resulting P > 100%.

2.2.8 Average Temperature of Fluid Stream

When a fluid is being heated, the temperature of the fluid is a maximum at the wall of the heating

surface and decreases toward the center of the stream. If the fluid is being cooled the temperature

is a minimum at the wall and increases toward the center. Because the temperature difference

between the hot and cold fluid streams varies along the length of the heat exchanger it is necessary

to derive an average temperature difference from which heat transfer calculations can be performed.

This average temperature difference is called the Logarithmic Mean Temperature Difference

(LMTD)

∆𝑇𝑙𝑚 = ∆𝑇1− ∆𝑇2

ln (∆𝑇1∆𝑇2

) ………….. (01)

10

2.2.9 Overall Heat Transfer Coefficient

It can be expected that the heat flux may be proportional to a driving force. In heat flow, the driving

force is taken as Th - Tc where Th is the average temperature of the hot fluid and Tc is that of the

cold fluid. The quantity Th - Tc is the overall temperature difference. It is denoted by ΔT. that T

can vary considerably from point to point along the tube, and therefore since the heat flux is

proportional to ΔT, the flux also varies with tube length. It is necessary to start with a differential

equation, by focusing attention on a differential area dA through which a differential heat flow dq

occurs under the driving force of a local value of ΔT. The local flux is then dx/dA and is related to

the local value of ∆𝑇𝑙𝑚

………………. (02)

The quantity U, defined by as a proportionality factor between dq/dA and ΔT, is called the local

overall heat-transfer-coefficient. To complete the definition of U in a given case, it is necessary to

specify the area. If A is taken as the outside tube area Ao, U becomes a coefficient based on that

area and is written Uo. Likewise, if the inside area Ai is chosen, the coefficient is also based on that

area and is denoted by Ui. Since ΔT and dq are independent of the choice of area, it follows that

………………… (03)

Where Di and Do are the inside and outside tube diameters, respectively. To apply Eq. 02 to the

entire area of a heat exchanger the equation must be integrated. The assumptions are ,

1. The overall coefficient U is constant.

2. The specific heats of the hot and cold fluids are constant.

3. Heat exchange with the surroundings is negligible.

The most questionable of these assumptions is that of a constant overall coefficient. The coefficient

does in fact vary with the temperatures of the fluids, but its change with temperature is gradual, so

that when the temperature ranges are moderate, the assumption of constant U is not seriously in

error.

Assumptions 2 and 4 imply that if Tc and Th are plotted against q, straight lines are obtained. Since

Tc and Th vary linearly with q, ΔT does likewise, and d(ΔT)/dq the slope of the graph of ΔT vs. q,

is constant. Therefore:

11

The variables ΔT and A can be separated, and if U is constant, the equation can be integrated over

the limits AT and 0 for A and ΔT2 and ΔT1 for ΔT, where AT is the total area of the heat-transfer

surface.

Thus,

Total heat transfer surface area in the tubular heat exchanger is defined as

Effectiveness-Net Transfer Units (NTU) Method

The heat exchanger effectiveness ε is define as,

ε = 𝑞

𝑞𝑚𝑎𝑥

𝑞𝑚𝑎𝑥 = 𝐶𝑚𝑖𝑛(𝑇ℎ,𝑖 − 𝑇𝑐,𝑖 )

𝑁𝑇𝑈 = 𝑈𝐴

𝐶𝑚𝑖𝑛

𝑇ℎ,𝑖, 𝑇𝑐,𝑖 = Temperature difference between hot and cold point

𝐶𝑚𝑖𝑛 = Heat capacity rate

12

ONGOING WORK AND DESIGN CALCULATIONS

3.1 Computer aided design of apparatus

The CAD model of heat exchanger lab apparatus was designed by using a solidwork software to

get basic idea of computer integrated heat exchanger test apparatus. Following figure shown how

is going to fabricate the apparatus.

Basic components of heat exchanger test apparatus as follows,

1 – Cold water storage tank

2 – Hot water storage tank

3 – 12V power supply

4 – Windshields water pump

5 – Thermal sensor (DS18B20)

6 – Microcontroller (Arduino)

7 – Motor controller

8 – Heat exchanger

Figure 3. CAD design of heat exchanger apparatus

13

3.2 Design calculations

3.2.1 Windshield pump

We were planning to fabricate heat exchanger test apparatus according to our basic CAD design as

shown above figure. First of all, we were calibrated windshield washer pump with respect to

different PWMs such as 50,100,150,200 and 250.

PWM VOLUME(ml) TIME(s) FLOW RATE (𝑚𝑙𝑠⁄ ) CURRENT(A) VOLTAGE (V)

50 600 121 4.95 0.43 12.0

100 600 85 7.06 0.72 12.0

150 600 69 8.70 1.16 9.0

200 600 54.2 11.07 1.38 9.0

250 600 37 16.22 1.65 9.0

Figure 4. Windshield washer pump

Table 1. Results of water pump calibration

14

3.3 Detailed design

Computer integrated heat exchanger practical unit was fabricated to study about variation

of heat transfer through the copper tube industrial was used for heating the water for supply to

Figure 5. Motor controller connect with Arduino AT-mega

Figure 6. Test apparatus for pump calibration

15

cupper tube that heater temperature was controlled by using inbuilt thermostat valve and for

circulation of hot water used the 12V wind shield pump that pump flow rate was controlled by

PWM signals. Cold water supplied by using gravity force.

Figure 7: Side view of Heat exchanger test apparatus

16

1 – DC power supply

2 – Wind shield pump

3 – Hot water inlet port

4 – Hot water outlet port

5 – Cold water inlet port

6 – Cold water outlet port

7 – Thermal sensor (DS18B20)

8 – AC power supply for Heater

Temperature sensors were mounted hot in and hot out chamber of inner pipe and cold in

cold out chamber of outer pipe then that temperature reading directly get lab view interface through

the arduino mega board.

Figure 8: Top view of heat exchanger

17

Computer integrated heat exchanger unit

Heat exchangers

1.Double pipe

2.Shell and tube

3.Plate type

Double pipe

Pumps

230 ac pump

12v dc pump

Wind shield pump

12V dc pump

12V dc wind shielded pump

Sensors

Thermocouple

LM 35

Ds18b20

DS18b20 sensor

Micro controller

Arduino

PIC

Arduino mega

Flow controller

VFD drive

L 298N

L298N

Software

Lab View

Visual basic

LabView

Module

NI 9211

Max 6675

The monitoring unit consist of following two software

• Arduino- to get temperature from sensors

• Labview-monitering temperature and plotting the graph

Conceptual Design

Mass flow rate Cold water Hot water

97.34(ml/s) 16.22(ml/s)

Table 2: conceptual design

18

Fabrication model

Design components

Double pipe heat exchanger unit

Double pipe heat exchanger include copper inner tube and PVC outer tube each of hot in

hot out and cold in cold out temperature’s measured by using (ds18b20) sensor.

Figure 9: fabricated model

Figure 10: double pipe heat exchanger

19

Hot water tank with heater

As hot water reservoir use the 5 liters tank combined with 1200w thermostat heater

Cold water tank with pump

As cold water reservoir use the 3 liters 12v dc pump the flow rate control by using speed control of

pump using pwm signal change use the labview interface.

Figure 11: Hot water tank with heater

Figure 12: Cold water tank with pump

20

Wind shield pump

This pump is use to circulate the hot water in heat exchanger the flow rate is controlled by changing

the PWM signals

Temperature sensors (ds1820)

To measure the temperature values of specific points, here was used a DS18B20 three wire

temperature sensor. Some specifications of temperature sensor as stainless steel tube encapsulation

waterproof and moisture proof. For this sensor signal pin and VCC pin should short circuit with

4.7K resistors

Stainless steel tube size: Approximately 6*50mm (Diameter*Length)

Operating temperature range: -55°C - +125°C (-67°F - +257°F)

Accuracy over the range of -10°C to +85°C: ±0.5°C.

Figure 13: wind shield pump

Figure 14: Temperature sensor

21

Motor controller (L298N)

L298N H-bridge IC that can allows you to control the speed and direction of two motors, control

one bipolar steeper motor with ease

Arduino mega

The arduino mega is microcontroller board on the AT mega 1280 it has 54 digital

input/output pins

Analog input pins: 16

DC current for 3.3V pins: 50mA

DC current per I/O pins: 40mA

Digital I/O pins : 54 (of which provided PWM output)

Figure 15: Motor controller

Figure 16: arduino mega

22

5 channel selector switch

This switch can select the position that switch is use to get the different temperature values on the

lab view interface

Electrical layout

Figure 17: 5 channel selector switch

Figure 18: Electrical layout

23

Lifabase Firmware

// Standard includes. These should always be included.

#include <Wire.h>

#include <SPI.h>

#include <Servo.h>

#include "LabVIEWInterface.h"

#include <OneWire.h> //For use with OneWire devices

#include <DallasTemperature.h> //For use with Maxim/Dallas DS18B20 or similiar

Temperature devices

//Defines for OneWire and Dallas Temperature

#define ONE_WIRE_BUS 2

//Setup a oneWire instance to communicate with any OneWire devices

OneWire oneWire(ONE_WIRE_BUS);

//Pass our oneWire reference to Dalls Temperature

DallasTemperature sensors(&oneWire);

/************************************************************************

*********

** setup()

**

** Initialize the Arduino and setup serial communication.

**

** Input: None

** Output: None

******************************************************************************

***/

void setup()

{

// Initialize Serial Port With The Default Baud Rate

syncLV();

24

// Place your custom setup code here

sensors.begin();

sensors.setResolution(9);

}

/************************************************************************

*********

** loop() ** ** The main loop. This loop runs continuously on the Arduino

Labview program

Digital port 8 and 9 port of arduino use for controlling the pumps speed through the L298N motor

controller as the speed controller use the knob button in lab view interface with indicator digital

port 2 that port is defined by (lifabase) use the (ds18b20) temperature sensors that temperature

parameters get the thermometer table and graph in lab view interface

Figure 19: labview program

25

Lab view interface

This interface can read the each temperature values without any delay and also it can get the graph

how to varying temperature with time and also it can control the both hot and cold water flow

rates.

Simulation model

Figure 20: Lab view interface

Figure 21: Simulation model

26

CAD version SOLIDWORKS 2016 SP0.1

CPU speed 2401 MHz

General Info

Model Assem11k.SLDASM

Project name double pipe

Project path D:\final year project\design\2

Units system SI (m-kg-s)

Analysis type Internal

Exclude cavities without flow

conditions

On

Coordinate system Global coordinate system

Reference axis X

INPUT DATA

Global Mesh Settings

Automatic initial mesh: On

Result resolution level: 3

Advanced narrow channel refinement: Off

Refinement in solid region: Off

Geometry Resolution

Evaluation of minimum gap size: Automatic

Evaluation of minimum wall thickness: Automatic

Computational Domain

Size

X min -0.023 m

X max 0.480 m

Y min 0.260 m

Y max 0.363 m

27

Z min 0.364 m

Z max 0.394 m

Boundary Conditions

2D plane flow None

At X min Default

At X max Default

At Y min Default

At Y max Default

At Z min Default

At Z max Default

Physical Features

Heat conduction in solids: On

Heat conduction in solids only: Off

Radiation: Off

Time dependent: Off

Gravitational effects: Off

Rotation: Off

Flow type: Laminar only

Cavitation: Off

High Mach number flow: Off

Default roughness: 0 micrometer

Default outer wall condition: Adiabatic wall

Initial Conditions

Thermodynamic parameters Static Pressure: 101325.00 Pa

Temperature: 293.20 K

Velocity parameters Velocity vector

Velocity in X direction: 0 m/s

Velocity in Y direction: 0 m/s

Velocity in Z direction: 0 m/s

28

Solid parameters Default material: Copper Tungsten

(Cu10/W90)

Initial solid temperature: 293.20 K

Material Settings

Fluids

Water

Solid Materials

Copper Tungsten (Cu10/W90) Solid Material 1

Boundary Conditions

Inlet Volume Flow 2

Type Inlet Volume Flow

Faces Face<1>@Part4-1

Coordinate system Face Coordinate System

Reference axis X

Flow parameters Flow vectors direction: Normal to face

Volume flow rate: 0.0001 m^3/s

Fully developed flow: No

Inlet profile: 0

Thermodynamic parameters Temperature: 323.00 K

Inlet Volume Flow 1

Type Inlet Volume Flow



Reference axis X

Flow parameters Flow vectors direction: Normal to face

Volume flow rate: 0.0002 m^3/s

Fully developed flow: No

Inlet profile: 0

Thermodynamic parameters Temperature: 303.00 K

29

Environment Pressure 1

Type Environment Pressure



Reference axis X

Thermodynamic parameters Environment pressure: 101325.00 Pa


Environment Pressure 2

Type Environment Pressure



Reference axis X

Thermodynamic parameters Environment pressure: 101325.00 Pa


Calculation Control Options

Finish Conditions

Finish Conditions If one is satisfied

Maximum travels 4

Goals convergence Analysis interval: 5.000000e-001

Solver Refinement

Refinement: Disabled

Results Saving

Save before refinement On

30

Advanced Control Options

Flow Freezing

Flow freezing strategy Disabled

RESULTS

General Info

Iterations: 217

CPU time: 117 s

Log

Mesh generation started 01:44:26 , Nov 20

Mesh generation normally finished 01:44:31 , Nov 20

Preparing data for calculation 01:44:32 , Nov 20

Calculation started 0 01:44:34 , Nov 20

Calculation has converged since the

following criteria are satisfied: 216

01:46:30 , Nov 20

Max. travel is reached 216

Calculation finished 217 01:46:31 , Nov 20




Calculation Mesh

Basic Mesh Dimensions

Number of cells in X 61

Number of cells in Y 13

Number of cells in Z 4

Number Of Cells

Cells 35779

Fluid cells 10206

Solid cells 25573

31

Partial cells 8504

Irregular cells 0

Trimmed cells 0

Min/Max Table

Name Minimum Maximum

Density (Fluid)

[kg/m^3]

987.52 987.52

Density (Solid)

[kg/m^3]

17170.00 17170.00

Pressure [Pa] 101318.14 101981.74

Temperature [K] 304.00 323.00

Temperature (Fluid)

[K]

304.00 323.00

Temperature (Solid)

[K]

323.00 323.00

Velocity [m/s] 0 2.311

Velocity (X) [m/s] -2.311 8.985e-024

Velocity (Y) [m/s] -0.005 0.005

Velocity (Z) [m/s] -0.008 0.009

Velocity RRF [m/s] 0 2.311

Velocity RRF (X)

[m/s]

-2.311 8.985e-024

Velocity RRF (Y)

[m/s]

-0.005 0.005

Velocity RRF (Z)

[m/s]

-0.008 0.009

Vorticity [1/s] 1.62e-023 1503.49

Relative Pressure [Pa] -6.86 656.74

Shear Stress [Pa] 2.90e-026 16.65

Bottleneck Number [ ] 2.0700438e-017 1.0000000

Heat Flux [W/m^2] 1.576e-004 0.911

32

Heat Transfer

Coefficient [W/m^2/K]

1.866e-009 0.028

Overheat above

Melting Temperature [K]

-1030.150 -1030.150

ShortCut Number [ ] 7.9225902e-031 1.0000000

Surface Heat Flux

[W/m^2]

-0.828 0.358

Engineering Database

Solids

Copper Tungsten (Cu10/W90)

Path: Solids Pre-Defined\Alloys

Density: 17170.00 kg/m^3

Specific heat: 149.2 J/(kg*K)

Conductivity type: Isotropic

Thermal conductivity: 160.0000 W/(m*K)

Electrical conductivity: Conductor

Resistivity: 6.4000e-008 Ohm*m

Radiation properties: No

Melting temperature: Yes


Liquids

Water

Path: Liquids Pre-Defined

33

Density

Dynamic viscosity

Specific heat (Cp)

Thermal conductivity

0

200

400

600

800

1000

1200

0 100 200 300 400 500 600

Den

sity

[kg/

m^3

]

Temperature[K]

0

0.0005

0.001

0.0015

0.002

0 100 200 300 400 500 600

Dyn

amic

vis

cosi

ty[P

a*s

]

Temperature[K]

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0 100 200 300 400 500 600

The

rmal

co

nd

uct

ivit

y[W

/(m

*K)]

Temperature[K]

4100

4200

4300

4400

4500

4600

4700

4800

4900

0 100 200 300 400 500 600

Spe

cifi

c h

eat

(Cp

)[J/

(kg*

K)]

Temperature[K]

34

Cavitation effect: Yes

Temperature: 0 K

Saturation pressure: 0 Pa

Radiation properties: No

3.4 Calculations

𝑇1= Temperature of entering hot fluid

𝑇2= Temperature of leaving hot fluid

𝑇3= Temperature of entering cold fluid

𝑇4= Temperature of leaving hot fluid

For parallel flow,

∆𝑇1=𝑇1-𝑇3

∆𝑇1= 49.6℃-29.3℃

= 20.3℃

∆𝑇2=𝑇2-𝑇4

∆𝑇2=48.5℃-29.9℃

=18.6℃

∆𝑇𝑙𝑚=∆𝑇1−∆𝑇2

𝑙𝑛∆𝑇1∆𝑇2

∆𝑇𝑙𝑚=20.3−18.6

𝑙𝑛20.3

18.6

= 19.43

Figure 22: Parallel flow

35

𝑄𝑒= Heat emitted from hot fluid

𝑄𝑎= Heat absorb from cold fluid

�̇�ℎ=Mass flow rate of hot fluid

�̇�𝑐=Mass flow rate of cold fluid

𝑐ℎ= Specific heat of hot fluid

𝑐𝑐= specific heat of cold fluid

𝑄𝑒= �̇�ℎ𝑐ℎ(𝑇ℎ,1 − 𝑇ℎ,2)

𝑄𝑎= �̇�ℎ(𝑇𝑐,1 − 𝑇𝑐,2)

𝑄𝑒=16.22*10−6*(49.6-48.5) *4134

=73.75W

𝑄𝑒=UA∆𝑇𝑙𝑚

A=outer surface of copper tube

A=2𝜋𝑅𝑜L

U=𝑄𝑒

𝐴∆𝑇𝑙𝑚

A=2*3.14*0.005*0.5𝑚2

=0.0157𝑚2

U=73.75

0.0157∗19.43

=241.76W/𝑚2𝑘

Experiential valve for cupper and water is 241.76W/𝑚2𝑘

Theoretical value range for cupper and water is 240-455 W/𝑚2𝑘

3.5 Future works

We have planned to do some future actives to conduct in near future. These activities will

help us to give a precious output with all functions. Our future plans mention as bellows.

Modify this apparatus to get both parallel & counter flow.

Insulate heat exchanger part to reduce losses.

Suppose to attach shell & tube and plate heat exchanger to this apparatus.

36

Figure 23: time Line

3.6 Time Line

37

BIBLIOGRAPHY

[1] A. Ltd, “Computer Controlled Heat Exchanger Service Module,” Armfield Ltd, 2016.

[Online]. Available: http://discoverarmfield.com/en/products/view/ht30xc/computer-

controlled-heat-exchanger-service-module. (May 2016)

[2] M. S. BIN ALIAS, “DESIGN OF SMALL HEAT EXCHANGER,” 2010.

[3] D. P. F. P. I. A. S. L. DeWitt, willey, 7th ed. wiley, 2011.

38

APPENDIX

DEPARTMENT OF MECHANICAL AND MANUFACTURING ENGINEERING

M3 – THERMODYNAMIC LABORATORY

MEXXXX: HEAT TRANSFER

Lab sheet

DATE :

TITLE : OVERALL HEAT TRANSFER COEFFICIENT

AIM :

NOTATIONS:

Symbol

To evaluate the performance of a Heat Exchanger in

counter flow under variations of flow rates

Description Units

U Overall heat transfer coefficient [kW/𝑚2K]

A Hot water tube surface area [𝑚2]

�̇�ℎ Mass flow rate of hot water [kg/s]

𝐶ℎ Specific heat of hot water [J/kg K]

𝑇1 Cold water inlet Temperature [K]

𝑇2 Cold water outlet Temperature [K]

𝑇3 Hot water inlet Temperature [K]

𝑇4 Hot water outlet Temperature [K]

𝑇5 Hot water reservoir tank Temp. [K]

∆𝑇1 , ∆𝑇2 Temperature difference [K]

𝑄ℎ Heat emitted by cold water [K]

∆𝑇𝑙𝑚 LMTD value [K]

THEORY:

Applying the First Law of Thermodynamics, to the hot water side,

𝑄ℎ = �̇�ℎ (𝑇3 − 𝑇4)

39

According to Logarithmic Mean Temperature Difference (LMTD) method,

𝑄ℎ = 𝑈 𝐴 ∆𝑇𝑙𝑚

𝑈 = 𝑄ℎ

𝐴 ∆𝑇𝑙𝑚

∆𝑇𝑙𝑚 = ∆𝑇1− ∆𝑇2

ln (∆𝑇1∆𝑇2

)

PROCEDURE:

Open drain valve for the heat exchanger apparatus (Cold water outlet).

Closed the drain valve for hot water reservoir.

Make sure the hot water reservoir is primed (full).

Make sure the hot water reservoir is full. And also connect the clear pipe of cold water

reservoir to tap water line.

Turn on the power to heat exchanger apparatus.

Turn on the computer, login and open "Overall Heat Transfer Coefficient" folder. And

also open LabVIEW software interface

Turn on the power to the heater & set the temperature controller to 80 ℃. And check the

T5 value by using interface.

Turn on the hot water supply pump at minimum flow rate.

Once T5 sensor value is 50 ℃, turn on the cooling water supply pump.

Changing following flow rates of hot water supply, take the temperature sensor readings.

OBSERVATIONS:

1 50 4.95 27 27.6 48 47.2 48.2

2 100 7.06 27 27.8 48.3 47.6 48.6

3 150 8.7 27.1 27.9 48.9 47.9 49.1

4 200 11.07 27.3 28.3 49.1 48.2 49.7

5 250 16.22 27 28.5 50.1 48.6 50.5

Test PWM Value MASS FLOW

RATE(kg/s)( )

Temperature (C)

𝑇1 𝑇2 𝑇3 𝑇4 𝑇510−3

40

DATA:

Diameter of copper tube = 0.01m

Length of copper tube = 0.50m

CALCULATIONS:

Find the overall heat transfer coefficient for Copper and Water.

RESULTS:

Write the results you obtained.

DISCUSSION:

Write a discussion describing the following points.

1. Practical importance of the experiment.

2. State the assumptions you made during the practical.

3. Point out the problems associated with the practical.

4. Mention the reasons for the deviation of the values you obtained from the theoretical values.

REFERENCE:

[1] “Experiment Lab Manual.” [Online]. Available:

https://web.njit.edu/~me/ME_406_Exp6_Lab_Manual.pdf. [Accessed: 19-Nov-2016].

computer intergrated heat exchanger laboratory apparatus

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