Study of a Refrigeration Unit (R633)

A Report on

STUDY OF A REFRIGERATION UNIT

Bangladesh University of Engineering and Technology

ChE 302

Chemical engineering laboratory - II

Experiment No. 7 Group No. 03 (A2)

Name of the experiment:

STUDY OF A REFRIGERATION UNIT

Submitted by:

Md. Hasib Al Mahbub

Student Id: 0902045

Level: 3; Term: 1

Section: A2

Date of performance: 28/04/2013

Date of submission: 19/05/2013

Partners Student Id. 0902041

0902042

0902043

0902044

Department of Chemical Engineering.

Bangladesh University of engineering and technology, Dhaka.

Page | ii

Summary

The objectives of this experiment were to be familiar with the refrigeration process and the

essential parts or units of the system (i.e., evaporator, compressor, condenser, and throttling

device or expansion valve) and also to know basic thermodynamics related to this process.

Specifically, this experiment aimed at the vapor compression refrigeration cycle with visual

observation including the investigation of the saturation pressure-temperature relationship

during evaporation and condensation, effect of evaporating and condensing temperature on

refrigeration rate, effect of compressor pressure ratio on system performance and to determine

the overall heat transfer coefficient. This experiment was conducted by Refrigeration Unit

R633 using refrigerant Forane-R141b (1,1-dichloro-1-flouroethane) to determine the overall

heat transfer coefficient between R141b and water in evaporator and condenser. Overall heat

transfer coefficient varied from 724.02 W/m2oC to 1148.35 W/m2oC and 583.15 W/m2oC to

805.50 W/m2oC for evaporator and condenser respectively. Graphs of Saturation pressure vs.

saturation temperature, rate of heat transfer vs. condensing temperature, rate of heat transfer

vs. compressor pressure ratio for both evaporator and condenser were plotted. Comparing with

the reference graphs and possible causes for discrepancies are stated in discussions.

Page | iii

Acknowledgement

First of all, I would like to thank our respected teacher, Tania Tabassum Emi, Lecturer,

Department of Chemical Engineering, BUET for the guidance and adjuration. Besides, I would

like to thank the authority of Bangladesh University of Engineering and Technology (BUET)

for providing us with a good facility to complete this report. Also, I would like to take the

opportunity to thank the Department of Chemical Engineering, Bangladesh University of

Engineering and Technology (BUET) for offering this course, Chemical Engineering

Laboratory-II. In addition, I would also like to thank my group partners who helped me in doing

the experiment.

Table of Contents

Page | iv

Title Page No.

Summary ii

Acknowledgement iii

1. Introduction 7

2. Theory 9

2.1 Assumptions for Ideal vapor compression refrigeration cycle 11

2.2 The Steps of Ideal Vapor Compression Cycle 12

2.3 Actual vapor-compression refrigeration cycle 14

2.4 Heat Transfer Coefficient 15

3. Experimental Setup 18

3.1 Apparatus 18

3.2 Chemical Used 18

3.3 Schematic Diagram 19

3.4 R633 Valve Position 20

3.5 Procedure 21

4. Observed Data 22

5. Calculated Data 23

6. Sample Calculation 24

7. Graph 26

7.1 Graph of Saturation pressure vs. Saturation temperature for both

evaporator and condenser

26

7.2 Graph of rate of heat transfer vs. condensing temperature for both


27

7.3 Graph of rate of heat transfer vs. compressor pressure ratio for both


28

8. Result 29

9. Discussion 30

10. Conclusion 35

References 36

Nomenclature 37

Appendices 38

Appendix A: Choice of Refrigerant. 39

Appendix B: Usage and Application of Refrigeration Process. 41

Appendix C: Other Refrigeration Processes (Modification). 43

Page | v

List of Illustrations

List of Figure

No. of Figure Name of Figure Page No.

1 Schematic diagram of a refrigeration unit 9

2 Schematic and T-s diagram for the ideal vapor compressor

refrigerator cycle

11

3 P-h diagram for the ideal vapor compressor refrigerator cycle 13

4 Vapor compressor refrigerator cycle in household refrigerator 13

5 Schematic and T-s diagram of an actual vapor-compression

refrigeration cycle

14

6 Refrigeration cycle demonstration unit R633 16

7 Schematic diagram of a refrigeration unit (R633) 19

8 Different valve position of refrigeration unit R633 20

9 Saturation pressure vs. saturation temperature curve for both


26

10 Rate of heat transfer vs. condensing temperature curve for both


27

11 Rate of heat transfer vs. compressor pressure ratio curve for both


28

12 The theoretical graph of saturation pressure vs. saturation

temperature for both evaporator and condenser

31

13 Theoretical graph of heat transfer vs. condensing temperature for

both evaporator and condenser

32

14 Theoretical graph of heat transfer vs. compressor pressure ratio for

both evaporator and condenser

33

15 A two-stage cascade refrigeration system with the same refrigerant

in both

43

16 A Multistage compression refrigeration systems 44

17 A Multipurpose refrigeration systems 45

18 Vapor-compression refrigeration system is by multistage

compression with regenerative cooling

46

19 Gas Refrigeration Systems 47

20 Absorption Refrigeration Systems 48

21 Thermoelectric Refrigeration Systems 49

Page | vi

List of Tables

No. of Table Name of Table Page No.

1 Observed Data for Vapor Compression of Refrigeration Cycle 22

2 Calculated Data of vapor Compression Refrigeration Cycle 23

3 Tabulated data of the results (rate of heat transfer, compressor

pressure ratio, and overall heat transfer coefficient for evaporator and

condenser)

29

4 List of symbols 37

Page | 7

1. Introduction

Refrigeration cycle is a sequence of thermodynamic processes whereby heat is withdrawn from

a cold body and expelled to a hot body. It is a reversed heat engine cycle. In general words

refrigeration refers to the process of removing heat from an enclosed space, or from a

substance, to lower its temperature. The device whose prime function is to do the job is known

as refrigerator and the working fluids used in the refrigeration cycle is called refrigerant. A

refrigerator uses the evaporation of a liquid to absorb heat. The liquid, or refrigerant, used in a

refrigerator evaporates at a low temperature, creating cooling or freezing temperatures inside

the refrigerator.

Including thermodynamics many other phases of engineering are involved in the design,

manufactures, application and operation of refrigeration system. The thermodynamic

properties of the refrigerants must be known before the cycle analysis can be made. Evaporators

and condensers of the system is used for the absorption and rejection of heat respectively

involved the fields of heat transmission. Steady state are involved in the determination of

cooling-load requirements. On the other hand, the design of reciprocating compressor involves

a variety of machine problems. The physical capacity of a compressor or expender will be

determined from thermodynamic factors.

The physical capacity of a compressor or expander can be determined from thermodynamic

factors. The measure of effectiveness of a refrigerator is its coefficient of performance (C.O.P).

It is the expression of the cycle efficiency and is stated as the ratio of the heat absorbed in the

refrigerated space to the heat energy equivalent of the energy supplied to the compressor.

The first known method of artificial refrigeration was demonstrated by William Cullen at the

University of Glasgow in Scotland in 1756. Cullen used a pump to create a partial vacuum over

a container of diethyl ether, which then boiled, absorbing heat from the surrounding air. The

experiment even created a small amount of ice, but had no practical application at that time.

Todays refrigeration process is far more advanced, easy to use and control and more

environment friendly, and thus it has become a very common system adopted at households

and many other places as the first cost and operating costs had also become reasonable.

Page | 8

The application of refrigeration are numerous in our daily life. The most widely used current

applications of refrigeration are for air conditioning of private homes and public buildings, and

refrigerating foodstuffs in homes, restaurants and large storage warehouses. In commerce and

manufacturing, there are many uses for refrigeration. Refrigeration is used to liquefy gases -

oxygen, nitrogen, propane and methane, for example. In compressed air purification, it is used

to condense water vapor from compressed air to reduce its moisture content. In oil refineries,

chemical plants, and petrochemical plants, refrigeration is used to maintain certain processes

at their needed low temperatures. Textile mills uses refrigeration in mercerizing, bleaching,

and dyeing. Manufacturers of paper, drugs, soap, glue, shoe polish, perfume, celluloid, and

photographic materials. Fur and woolen goods storage could beat the moths by using

refrigerated warehouses. So it is important to have a general knowledge on refrigeration which

has prompted to conduct the experiment.

The experiment has been performed to study various components of a refrigeration unit

physically and operating it at different operating modes to get acquainted with this process and

all of its essential parts and also to know the thermodynamic basics of refrigeration thoroughly

and specially the overall heat transfer coefficient so that the operations may become well

known to us and a platform for further modification is created.

Page | 9

2. Theory

Refrigeration implies the maintenance of a temperature below that of the surroundings. This

requires continuous absorption of heat at a low temperature level usually accomplished by

evaporation of a liquid in a steady-state flow process. The vapor reformed to liquid state for re-

evaporation generally by compressing and then condensing by rejecting heat at a higher

temperature consecutively Refrigeration cycle is a sequence of thermodynamic processes

whereby heat is withdrawn from a cold body and expelled to a hot body, which is a reversed

heat-engine cycle. According to the 2nd law of thermodynamics it required an external source

of energy or external work done on the system to transfer heat from a lower temperature level

to a higher one.

A refrigerator is shown schematically in figure 1. Here QL is the magnitude of the heat removed

from the refrigerated space at temperature TL. QH is the magnitude of the heat rejected to the

warm space at temperature TH, and Wnet in is the net work input the refrigerator (R).

Figure 1. Schematic diagram of a refrigeration unit

Warm

environment

R

QH

QL (Desired output)

Wnet, in (Required input)

Cold

refrigerated

space

Page | 10

In such a case the performance of refrigerators is expressed in terms of the coefficient of

performance (COP), defined as

COP =Desired output

Required input =

Cooling effect

Work input =

QL

Wnet,in ... ... ... ... ... ... ... ... ... (2.1)

Since energy cannot be destroyed, the heat taken in at low temperature plus any other energy

input must be dissipated to the surroundings. The Clausius statement of the second law of

thermodynamics states that heat will not pass from a cold to a hotter region without the aid of

an external agency. Thus a refrigerator will require an input of high grade energy for it to

operate. The most common type of refrigerator uses a work input and operates on the Vapor

compression cycle. The work input to the Vapor Compression Cycle derives a compressor

which maintains a low pressure on an evaporator and a higher pressure in condenser. The

temperature at which a liquid will evaporate (or a vapor will condense) is dependent on

pressure, thus if a suitable fluid is introduced it will evaporate at a low temperature in the low

pressure evaporator (taking in heat) and will condense at a higher temperature in the high

pressure condenser (rejecting heat). The high pressure liquid formed in the condenser must

then be returned to the evaporator at a controlled rate. Thus, the simple vapor compression

refrigeration cycle has four main component1,

(1) An evaporator where heat is taken in at a low temperature as a liquid evaporator at a

low pressure.

(2) A compressor which uses a work input to reduce the pressure in the evaporator and

increase the pressure of the vapor being transferred to the condenser.

(3) A condenser where the high pressure vapor condenser, rejecting heat to its

surroundings.

(4) A flow control device which controls the fowl of liquid back to the evaporator and

which brings about the pressure reduction.

The refrigeration cycle is most interesting from the thermodynamic view point. It is one of the

few practical plants which operates on a true thermodynamic cycle and involves8-

(a) Nucleate boiling and film wise condensation.

(b) Steady flow process, i.e. throttling, compression and heat exchange.

(c) Flow control.

Page | 11

(d) The thermodynamic properties, i.e. pressure, specific volume, temperature, specific

enthalpy and entropy of a pure substance at all conditions between sub-cooled liquid

and super-heated vapor.

The refrigeration cycle can be described by and ideal process operated on a Carnot cycle and

then can be converted to the actual cycle or actual changes in entropy and enthalpy during the

process. The Carnot cycle for refrigeration consists of 4 steps as well similar to heat engine.

The phase changes of the refrigerant in the vapor compression cycle are the main key process

of the refrigeration system and they can be represented by the T-S diagram in figure 2.

2.1 Assumptions for Ideal vapor compression refrigeration cycle2

Irreversibility within the evaporator, condenser and compressor are ignored

No frictional pressure drops

Refrigerant flows at constant pressure through the two heat exchangers (evaporator and

condenser)

Stray heat losses to the surroundings are ignored

Compression process is isentropic

Figure 2. Schematic and T-s diagram for the ideal vapor compressor refrigerator cycle.5

QH

Warm

Cold

Evaporator

Condenser

Compressor

QL

Expansion

Valve Win

1

2 3

4

Saturated

liquid

Saturated vapor

QL

QH

Win

T

S

Page | 12

2.2 The Steps of Ideal Vapor Compression Cycle:

The cycle operates on following four process:6

1-2: Isentropic compression

2-3: Constant pressure heat rejection (Condenser)

3-4: Adiabatic expansion in a throttling device

4-1: Constant pressure heat absorption (Evaporator)

I. (1-2) Isentropic compression in a compressor: A compressor which uses a work input

to reduce the pressure in the evaporator and increase the pressure of the vapor being

transferred to the condenser. External work is done on the cycle to initiate the cycle to

flow heat from lower temperature to higher. The saturated vapor outlet from evaporator

goes in the compressor and is compressed to superheated vapor. Here the ideal process

is an isentropic process but in actual case the entropy increases due to increase in

temperature. The compression process is represented by line 1-2 in figure 2.

II. (2-3) Constant pressure heat rejection in a condenser: A condenser where the high

pressure vapor condenses, rejecting heat to its surroundings. This is another isothermal

process in which heat QH is rejected at higher temperature in the condenser. The

superheated vapor from the outlet of the compressor goes in the condenser and cooled

to saturated vapor and then condensed to saturated liquid by rejecting latent heat to the

surrounding at higher temperature (room temperature) The condensation process is a

constant pressure and temperature process which is represented by 2-3 line in the

figure 2.

III. (3-4) Adiabatic expansion in a throttling device: it is an adiabatic process and also

an isenthalpic process of expansion. An expansion device (throttle valve) is used to get

back the refrigerant to its original pressure at the inlet of evaporator. The pressure drop

in this irreversible process results from fluid friction in the valve. At the inlet of the

throttle valve the refrigerant is saturated liquid and due to expansion, it is converted to

a liquid vapor mixture at outlet. This process is represented by line 3-4 in figure 2.

IV. (4-1) Constant pressure heat absorption in an evaporator: It is an isothermal step

in which heat QL is absorbed at the lower temperature in the evaporator. Here the

liquid refrigerant evaporates at constant pressure and temperature absorbing the latent

heat of vaporization. The inlet of the evaporator is a liquid-vapor mixture and absorbing

Page | 13

heat from air of lower temperature (room temperature in this case) it becomes saturated

vapor. The process in evaporator is represented by line4-1 in figure 2.

The P-h diagram in figure 3 is another convenient diagram often used to illustrate the

refrigeration cycle. Where, process 1-2 indicates isentropic compression process, process 2-3

indicates P = constant heat rejection process, process 3-4 indicates expansion under throttling

process, h = constant, process 4-1 stands for P = constant heat addition process.

Figure 3. P-h diagram for the ideal vapor compressor refrigerator cycle.7

The ordinary household refrigerator is a good example of the application of this cycle-

Figure 4. Vapor compressor refrigerator cycle in household refrigerator.3

Evaporator coil

Freezer

compartment

Capillary tube

QH

Condenser coil

Compressor

QL

Kitchen air

25

3

-18

Page | 14

2.3 Actual vapor-compression refrigeration cycle1

An actual vapor-compression refrigeration cycle differs from the ideal one in several ways,

owing mostly to the irreversibilities that occur in various components. Two common sources

of irreversibilities are fluid friction (causes pressure drops) and heat transfer to or from the

surroundings. The T-s diagram of an actual vapor-compression refrigeration cycle is shown in

Figure 5.

Figure 5. Schematic and T-s diagram of an actual vapor-compression refrigeration cycle.

The reason for the deviation is that, there are frictional effects that result in pressure drops as

the refrigerant flows through the condenser, evaporator, and the piping connecting various

components in the actual cycle. The actual compression process (process 1-2) starts in

superheated vapor region, not on the saturated vapor line. The actual compression process is

irreversible (not isentropic) and goes in the direction of increase of entropy (S2>S1). The

isentropic efficiency of the compressor is used to evaluate the performance of the compressor

and define enthalpy at the exit of the actual compressor (point 2). And at the end of the actual

heat rejection process in the condenser (process 2-3) the liquid is sub cooled, not saturated.

Warm

Cold

Evaporator

Condenser

Compressor

QL

Expansion

Valve Win

1

2 5

7

3 4

6

8

1

2 3

2`

4

5 6 7 8

T

s

Page | 15

2.4 Heat Transfer Coefficient

Heat transfer coefficient is defined as the amount of heat which passes through a unit area of a

medium or system in a unit time when the temperature difference between the boundaries of

the system is 1 degree.2 The heat transfer coefficient, in thermodynamics and in mechanical

and chemical engineering, is used in calculating the heat transfer, typically by convection or

phase transition between a fluid and a solid:

Where

Q = heat flow in input or lost heat flow, J/s = W

h = heat transfer coefficient, W/ (m2K)

A = heat transfer surface area, m2

T= difference in temperature between the solid surface and surrounding fluid area

From the above equation, the heat transfer coefficient is the proportionality coefficient between

the heat flux, that is heat flow per unit area, q/A, and the thermodynamic driving force for the

flow of heat (i.e., the temperature difference, T).

The heat transfer coefficient has SI units in watts per square meter kelvin: W/ (m2K).

The overall heat transfer coefficient (U) is a measure of the overall ability of a series of

conductive and convective barriers to transfer heat1. It is commonly applied to the calculation

of heat transfer in heat exchangers, but can be applied equally well to other problems.

For the case of a heat exchanger, U can be used to determine the total heat transfer between the

two streams in the heat exchanger by the following relationship:

Where

Q = heat transfer rate, W

U = overall heat transfer coefficient, W/ (mK)

A = heat transfer surface area, m2

TLMTD = log mean temperature difference, K

U=

Q

ATLMTD

... ... ... ... ... ... ... ... ... (2.2)

... ... ... ... ... ... ... ... ... (2.3)

Page | 16

With the use of refrigeration cycle demonstration unit R633 (Figure 6) in laboratory, following

steps leads to the calculation of overall heat transfer coefficient (U).

Figure 6. Refrigeration cycle demonstration unit R633

Absolute pressure= Gauge pressure (pe) + Atmospheric pressure (P)

Saturation pressure of Evaporator, Pe = pe + P

Saturation pressure of Compressor, Pc = pc + P

Rate of heat transfer for Evaporator, Qe= meCp(t1-t2)

Rate of heat transfer for Condenser, Qc= mcCp(t3-t4)

Where

Cp = Specific Heat of Water, (KJ/Kg .K)

me = Evaporator Water Flow rate

mc = Condenser Water Flow rate

t1 = Evaporator Water Inlet Temperature, ()

t2 =Evaporator Water Outlet Temperature, ()

t3 =Condenser Water Outlet Temperature, ()

t4 =Condenser Water Inlet Temperature, ()

Finally,

Overall Heat Transfer Coefficient,

U=

Q

ATLMTD

Page | 17

Where each term Q, A and TLMTD refer to the corresponding value for condenser and

evaporator

TLMTD =

Where

Tin= temperature difference of water inlet and supplied refrigerant.

Tout= temperature difference of water outlet and supplied refrigerant.

Tin

Tout

Tin-Tout

ln ( ) ... .... ... ... ... ... ... ... ... ... (2.4)

Page | 18

3. Experimental Setup

3.1 Apparatus

Compressor

Temperature indicator

Condenser rotameter

Evaporator rotameter

Condenser

Evaporator

Condenser pressure gauge

Evaporator pressure gauge

Condenser inlet thermometer

Condenser outlet thermometer

Evaporator inlet thermometer

Evaporator outlet thermometer

Condenser thermometer

Evaporator thermometer

Throttle valve

Compressor discharge thermometer

Control valve

Switcher

Capillary tube

Water reservoir

Pump

3.2 Chemical Used

R141b (1,1-dichloro-1-fluoroethane)

Water

Fig

ure

7.

Sch

em

ati

c d

iagra

m o

f a r

efri

ger

ati

on

un

it (

R6

33)

Outl

et C

onden

ser

Ther

mom

eter

Conden

ser

Pre

ssure

Gau

ge

Conden

ser

Ther

mom

eter

Inle

t C

onden

ser

Ther

mom

eter

Conden

ser

Rota

met

er

Tem

per

ature

Indic

ator

Inle

t E

vap

ora

tor

Ther

mom

eter

Evap

ora

tor

Pre

ssure

Gau

ge

Evap

ora

tor

Th

erm

om

eter

Outl

et E

vap

ora

tor

Ther

mom

eter

Evap

ora

tor

Rota

met

er

Evap

ora

tor

Conden

ser

Thro

ttle

Val

ve

Wat

er O

utl

et

Com

pre

ssor

Wat

er R

eser

voir

Pum

p

3.3 Schematic diagram

3.4 R633 Valve Position

Normal Operation

Refrigerant Pump Down

Oil Return

Shutdown

Figure 8. Different valve position of refrigeration unit R633

Page | 21

3.5 PROCEDURE

The main components of the refrigeration unit were identified.

The piping and control system were studied.

The cooling water supply and mains supply to the unit were turned on.

Water supply to the unit was turned on and the evaporator water flow rate was adjusted

to 10 g/s and condenser water flow rate was adjusted to 50 g/s using control valve.

When the main switch was turned on, then the compressor was started and the two

internal lamps were lighted.

The evaporator pressure and the compressor pressure were set approximately at -75

KN/m2 and 120 KN/m2.

The unit was allowed to run approximately 15 minutes in order to reach suitable

temperature and pressure.

The temperatures (t1, t2, t3, t4, t5, t6, t7, t8), pressure pe and pc, water flow rate me and mc

were recorded.

Similarly steps h - i were repeated after reducing condenser water flow rate to 40 g/s,

30 g/s, 20 g/s, 10 g/s.

Page | 22

4. Observed Data

Water Coil Surface Area of Condenser, Ac= 0.032 m2

Water Coil Surface Area of Evaporator, Ae=0.032 m2

Specific Heat of Water, Cp= 4.18 KJ/Kg .K

Refrigerant used= R141b (1, 1- dichloro-1-fluroethane) of approximately 800 cm3

Normal Boiling Point= 32

Local Atmospheric Pressure, P= 101.325 KN/m2

Table 1. Observed Data for Vapor Compression of Refrigeration Cycle.

Number of observation 1 2 3 4 5

Evaporation Gauge pressure, pe (KN/m2) -70 -68 -70 -69 -68

Absolute Evaporator pressure, Pe (KN/m2) 31.33 33.33 31.33 32.33 33.33

Evaporator temperature, T5 () 7 8 8 6 7

Evaporator water flow rate, e (g/s) 4 7 4 4 4

Evaporator Water Inlet Temperature, T1 () 15 14 17 18 19

Evaporator Water Outlet Temperature, T2

() 9 10 9 9 10

Condensed Liquid Temperature, T8 () 24.10 25.40 26.90 28.30 31.1

Condenser Gauge Pressure, pc (KN/m2) 50 54 59 65 78

Absolute Condenser Pressure, Pc (KN/m2) 151.33 155.33 160.33 166.33 179.33

Compressor Discharge Temperature, T7 () 43 44 49 52 53

Condenser Temperature, T6 () 23 24 26 27 30

Condenser Water Flow Rate, c (g/s) 50 40 30 20 10

Condenser Water Inlet Temperature, T4 () 12 13.5 15.5 17 18

Condenser Water Outlet Temperature, T3 () 13 15 17 19 23

Page | 23

5. Calculated Data

Table 2. Calculated Data of vapor Compression Refrigeration Cycle.

Number of Observation 1 2 3 4 5

Saturation Pressure of Evaporator,

Pe (KN/m2) 31.33 33.33 31.33 32.33 33.33

Saturation Pressure of Condenser,

Pc (KN/m2) 151.33 155.33 160.33 166.33 179.33

Rate of Heat Transfer for

Evaporator, Qe (W)=meCp(t1-t2) 100.32 117.04 133.76 150.48 150.48

Rate of Heat Transfer for Condenser,

Qc (W) )=mCCp(t3-t4) 209 250.80 188.1 167.20 209

Compressor Pressure Ratio,

4.83 4.66 5.12 5.14 5.38

Temperature difference for

evaporator inlet, Tin,e= t1-t5 8 6 9 12 12


evaporator outlet, Tout,e= t2-t5 2 2 1 3 3

TLMTD(Evaporator)()=,,

(,

,)

4.33 3.64 3.64 6.49 6.49


condenser inlet, Tin,c= t6-t4 11 10.5 10.5 10 12


condenser outlet, Tout,c=t6-t3 10 9 9 8 7

TLMTD (Condenser)()=,,

(,

,)

10.49 9.73 9.73 8.96 9.28

Overall Heat Transfer Coefficient

(Evaporator), Ue (W/m2)=

724.02 1004.81 1148.35 724.58 724.58

Overall Heat Transfer Coefficient

(Condenser), Uc (W/m2)=

622.62 805.50 604.12 583.15 703.80

Page | 24

6. Sample Calculation

Sample calculation for observation- 5

Atmospheric pressure = 101.325 KN/m2

Water coil surface area in Evaporator, Ae = 0.032 m2

Water coil surface area in Condenser, Ac = 0.032 m2

Evaporator gauge pressure, pe = -68 KN/m2

Evaporator absolute pressure, Pe = (-68+101.325) KN/m2

= 33.33 KN/m2

Condenser gauge pressure, pc = 78 KN/m2

Condenser absolute Pressure, Pc = (78+101.325) KN/m2

= 179.325 KN/m2

Compressor Pressure Ratio,

=

179.325

33.33 = 5.38

Evaporator water flow rate, e = 4 g/s

Evaporator water inlet temperature, t1 = 19

Evaporator water outlet temperature, t2 =10

Rate of heat transfer to water in evaporator, Qe = eCp(t1-t2)

= 44.18(19-10) W

= 150.48 W

Condenser water flow rate, c = 10 g/s

Condenser water inlet temperature, t4 = 18

Condenser water outlet temperature, t3 = 23

Rate of heat transfer to water in Condenser, Qc = cCp(t3-t4)

= 104.18(23-18) W

= 209 W

Page | 25

For Evaporator

Evaporator temperature, t5 = 7

Tin = ( t1- t5 )

= (19-7)

=12

Tout = (t2- t5)

= (10-7)

= 3

TLMTD =

ln(

)

= 123

ln(12

3)

= 6.49

For evaporator overall heat transfer coefficient, Ue =

= 150.48

0.0326.49 W/m2

= 724.58 W/m2

For Condenser

Condenser temperature, t6 = 30

Tin = ( t6- t4 )

= (30-18)

= 12

Tout = ( t6- t3 )

= (30-23)

= 7

TLMTD =

ln(

)

= 127

ln(12

7)

= 9.28

For condenser overall heat transfer coefficient, Ue =

= 209

0.0329.28W/m2.0 C

= 703.79 W/m2

703.8 W/m2

Page | 26

7. Graphs

7.1 Graph of Saturation pressure vs. Saturation temperature for both evaporator and condenser

Figure 9. Saturation pressure vs. saturation temperature curve for both evaporator and

condenser

y = 32.33

R = 0

y = 3.9667x + 59.397

R = 0.9859

0

20

40

60

80

100

120

140

160

180

200

0 5 10 15 20 25 30 35

1 s

mal

l sq

uar

e =

5 K

Pa

Sat

ura

tion P

ress

ure

, (

KP

a )

Saturation Temperature, ( C ) 1 small square = 1C

Evaporator

Condenser

Page | 27

7.2 Graph of rate of heat transfer vs. condensing temperature for both evaporator and condenser

Figure 10. Rate of heat transfer vs. condensing temperature curve for both evaporator

and condenser

y = 7.3825x - 70.093

R = 0.8415

y = 4.0215x + 53.305

R = 0.9914

90

100

110

120

130

140

150

160

170

180

190

22 23 24 25 26 27 28 29 30 31 32

Rat

e of

hea

t tr

ansf

er f

or

both

evap

ora

tor

and

co

nd

ense

r(W

)

(1 s

quar

e unit

= 2

W)

Condensing temperature(C) (1 square unit = 0.4 C )

Evaporator

Condenser

Page | 28

7.3 Graph of rate of heat transfer vs. compressor pressure ratio for both evaporator and condenser

Figure 11. Rate of heat transfer vs. compressor pressure ratio curve for both evaporator and

condenser

y = 64.155x - 192.03

R = 0.6918

y = -68.943x + 551.33

R = 0.3951

80

100

120

140

160

180

200

220

240

260

4.6 4.7 4.8 4.9 5 5.1 5.2 5.3 5.4 5.5

Rat

e of

hea

t tr

anfe

r fo

r both

evap

ora

tor

and

co

nd

ense

r(W

)

1 s

quar

e um

it =

10 W

Compressor pressure ratio

1 square unit = 0.04

Evaporator

Condensor

Page | 29

8. Result

Results obtained in the experiment are shown below:

Table 3. Tabulated data of the results (rate of heat transfer, compressor pressure ratio,

and overall heat transfer coefficient for evaporator and condenser).

Observation

Number

Rate of Heat

Transfer to

Water in

Evaporator,

Qe (W)

Rate of Heat

Transfer to

Water in

Condenser,

Qc (W)

Overall Heat

Transfer

Coefficient,

Ue(W/m2.)

Over all Heat

Transfer

Coefficient,

Uc(W/m2.)

Compressor

Pressure

Ratio,

( Pc / Pe)

1 100.32 209 724.02 622.62 4.83

2 117.04 250.8 1004.81 805.50 4.66

3 133.76 188.1 1148.35 604.12 5.12

4 150.48 167.2 724.35 583.15 5.14

5 150.48 209 724.58 703.80 5.38

Page | 30

9. Discussion

From the calculated data the required graphs, i.e.

I. Saturation pressure vs. Saturation temperature curve,

II. Rate of heat transfer vs. Condensing temperature curve and

III. Rate of heat transfer vs. Compressor pressure ratio curve for both evaporator and

condenser

are shown above. Though the curves shows the general characteristics somewhat accurately,

these experimental curves show some deviations from the theoretical curves. The major causes

for the deviation of the experimental graphs4 from the theoretical graphs are discussed below.

i) Saturation pressure vs. Saturation temperature curve

The relationship between saturation pressure and temperature was observed in both evaporator

and condenser. However variation of evaporating temperature was small for all but extreme

changes in cooling water flow.

As the condenser contains refrigerants in all stages from superheated vapor through to sub

cooled liquid the thermometer pocket t6 only records temperature close to saturation when the

pocket is showing signs of condensed liquid. Therefore it is recommended that the pressure

temperature relationship in the condenser is investigated as the condenser pressure increases.

In case of investigating pressure temperature relationship by reducing the condenser pressure

then the t6 thermometer pocket will be at a temperature that is higher than the surrounding

vapor due to its thermal inertia. Therefore no vapor will condense on the pocket and an

incorrect temperature will be measured.

The theoretical graph of saturation pressure vs. saturation temperature for both evaporator and

condenser for R141b is shown below. Here the standard pressure gauge accuracy of 1% of

gauge full scale has been shown as dotted lines about a mean. We can see from the graph that,

the curves of condenser and evaporator are so close and the trend line seems to be a single one.

But form the experimental graph (figure. 12), it can be seen that they are far apart due to the

discrepancies like reading errors, absolute accuracy of temperatures etc.

Page | 31

Figure 12. The theoretical graph of saturation pressure vs. saturation temperature for

both evaporator and condenser4

ii) Rate of heat transfer vs. Condensing temperature curve

The effect of evaporating temperature on the refrigerator rate could be investigated, but due to

the limited effect on evaporating temperature it is more graphic to investigate condensing

temperature. The effect of increasing the condensing temperature on many refrigeration system

and heat pumps is a reduction in the heat discharge from the condenser and in many cases a

smaller reduction in the refrigerating effect at the evaporator.

The following theoretical graph shows that the heat transfer at the condenser decreases as the

condensing temperature increases. From the graph it can be seen that the evaporator curve is

parallel to x-axis and condenser curve makes a negative slope. But form the experimental graph

it can be seen that the evaporator curve is not parallel to x- axis and condenser curve is different

from the theoretical one. Here heat transfer rate for both evaporator and condenser increases

with condensing temperature. Which may be due to the discrepancies like pressure variation,

reading error etc.

Page | 32

Figure 13. Theoretical graph of heat transfer vs. condensing temperature for both

evaporator and condenser4

iii) Rate of heat transfer vs. Compressor pressure ratio curve for both evaporator

and condenser

The theoretical curve for the Rate of heat transfer vs. Compressor pressure ratio shows that the

heat transfer at the condenser decreases as the compressor pressure ratio increases. From the

graph it can be seen that the evaporator curve is parallel to x-axis and condenser curve makes

a negative slope. form the experimental graph it can be seen that condenser curve is same as

the theoretical one but the evaporator curve is not parallel to x- axis rather it is positively sloped

and. Here heat transfer rate increases for evaporator and decreases for condenser with

compressor pressure ratio.

Page | 33

Figure 14. Theoretical graph of heat transfer vs. compressor pressure ratio for both

evaporator and condenser4

The deviation of experimental curves and some observations of data for which the rate of heat

transfer was not identical with other calculated value which might cause from the following

discrepancies.

The experiment and the calculations was done considering the system to be operated

on ideal Carnot cycle. But in actual case the conditions vary from the ideal one. The

actual compression process starts in superheated vapor region, not on the saturated

vapor line. The actual compression process is irreversible (not isentropic) and goes in

the direction of increase of entropy. And at the end of the actual heat rejection process

in the condenser the liquid is sub cooled, not saturated.

Presence of air in refrigeration unit causes the compressor delivery pressure to rise,

reducing the coefficient of performance. This increase of pressure is generally due to -

(i) the total pressure in the condenser is approximately equal to the sum of the

refrigerant saturation pressure and the pressure of the air present. And (ii) the air tends

to be swept towards the heat transfer surfaces, forming an insulated layer which reduces

the heat transfer coefficient

Page | 34

Because of fluid friction small pressure drops occur and some error is found in

calculation. A small heat exchange also occurs with the surroundings of the system as

the system cant be insulated in such a way so that no heat is exchanged with the

surroundings.

Another cause for the deviation of the vapor compression cycle applied for actual

refrigeration cycles from the Carnot cycle is due to the irreversibility in expansion in

the throttle valve and also in the compression process. Error is found therefor in the

calculation and experimental graphs deviate from the theoretical one.

Pressure of condenser was increasing very rapidly and was not stable enough to get

accurate values of temperature for corresponding pressure of condenser.

Mass flow rate had to be controlled by observing the flow meter as the flow rate was

not constant in any certain observation. It was fluctuating a little bit.

Page | 35

10. Conclusion Modern life has reached in such position that temperature control is unavoidable in various

cases which cant be imagined without refrigeration. So it is important to have an overall

knowledge about refrigeration system, its different parts and operating modes. Selection of

refrigerator for any purpose depends on refrigerant types, efficiency required, system

characteristics and environmental feature. In this experiment all the separate parts of the

refrigeration unit, their structure and mechanisms had been well observed and studied. The

objective of this experiment have been completely achieved as required and at the same time,

all the parameters required to be solved have been calculated and solved accordingly. In

addition, all of the experiments have eventually being done according to the procedures given

systematically and appropriately. There were many discrepancies while performing the

experiment due to which experimental data deviates from the theoretical one. But still it is very

helpful to acquire a general idea on refrigeration.

Page | 36

References

1. Abbot, M. M., Van Ness, and Smith, J. M., (2001), Introduction to CHEMICAL

ENGINEERING THERMODYNAMICS, 6th edition, Tata McGraw-Hill Publishing

Company Limited, pp. 309-322.

2. Cengel, Y. A. and Boles, M. A., (2006), THERMODYNAMICS An Engineering

Approach, 5th edition, Tata McGraw-Hill Publishing Company Limited, pp. 607-637.

3. Perry, R. H. and Green, D. W., (1997) Perrys Chemical Engineers Handbook, 7th

edition, McGraw-Hill, New York, pp. 11/76-11/80.

4. Experimental Operating and Maintenance Manual Refrigeration cycle

demonstration unit. P. A. Hilton Ltd. SI no 3080 Feb. 96, pp. 4, 27-29, 36-38, 40-42.

5. Richard C. Jordan & Gayle B. Priester Refrigeration and Air Conditioning, Chapter-

2, pp. 16-17,423

6. C P Arora, Refrigeration and Air conditioning, 2nd edition, Tata McGraw-Hill

Publishing Company Limited, New Delhi, 2000, pp. 113,119.

7. Andrew D. Althouse, Carl H. Turnquist, Alfred F. Bracciano, Modern Refrigeration

And Air Conditioning, The Goodheart-Wilcox Company, Inc.1968, pp. 319-324.

8. Stoecker W. S., (1998), Industrial Refrigeration Handbook, McGraw-Hill, New

York, pp. 115-120.

Page | 37

Nomenclature

List of symbols used throughout the report are given below:

Table 4. List of symbols

Symbol Significance Unit (SI)

COP Coefficient of performance Unitless

h Enthalpy J

I Current Amp

P Pressure KPa

Q Supplied heat Watt

Qc Heat removed from cold reservoir Watt

QH Heat supplied to hot reservoir Watt

QL Amount of heat of low temperature source Watt

S Entropy KJ K-1

Tm Logarithmic Mean Temperature Difference

(LMDT) C

Tcold Temperature of cold reservoir C

Thot Temperature of hot reservoir C

TH Temperature of condenser C

TL Temperature of evaporator C

U Overall Heat Transfer Coefficient W/m2C

W Work J

Page | 38

Appendices

A. Choice of Refrigerant.

B. Usage and Application of Refrigeration Process.

C. Other Refrigeration Processes (Modification).

Page | 39

Appendix A: Choice of Refrigerant

Factors which affect the efficiency of a refrigeration system are:

the refrigerant performance

heat exchangers

evaporating temperature

condenser temperature

compressor efficiency

pipe sizing

The coefficient of performance of a carnot refrigerator is independent of the refrigerant.

However, the irreversibilities inherent in the vapor compression cycle cause the COP of

practical refrigerators to depend to some extent on the refrigerant. The following characteristics

of a refrigerant are important in case of selection:

Toxicity

Flammability

Chemical stability

Cost

Corrosion properties

Vapor pressure in relation to temperature

Thermal factors

Ozone depletion

Global warming impact

If the refrigerant is toxic or flammable it will be very hazardous and injurious to health if even

a small leakage of the system takes place which is not an abnormal phenomenon. If it is

flammable then explosion can take place easily in case of leakage or if pressure is built up

inside somehow.

Cost is also an important factor for smaller units costly refrigerant can be used but in industrial

purpose optimization of cost is required.

If the refrigerant is corrosive then the whole unit would be affected and would sustain smaller

period of time than expected.

Page | 40

The vapor pressure of the refrigerant at the evaporator temperature should be greater than

atmospheric pressure so that air cannot leak into the refrigeration system. On the other hand,

the vapor pressure of the refrigerant at condenser temperature should not be unduly high,

because of the initial cost and operating expense of high pressure equipment. These two

requirements limit the choice of refrigerant to relatively few fluids. The final selection then

depends on the other characteristics.

Thermal Factors

The heat of vaporization of the refrigerant should be high. The higher hfg, the greater

the refrigerating effect per kg of fluid circulated

The specific heat of the refrigerant should be low. The lower the specific heat, the less

heat it will pick up for a given change in temperature during the throttling or in flow

through the piping, and consequently the greater the refrigerating effect per kg of

refrigerant

The specific volume of the refrigerant should be low to minimize the work required

per kg of refrigerant circulated

Since evaporation and condenser temperatures are fixed by the temperatures of the

surroundings- selection is based on operating pressures in the evaporator and the

condenser

Ozone Depletion Potential

chlorinated and brominated refrigerants

acts as a catalyst to destroy ozone molecules

reduces the natural shielding effect from incoming ultra violet B radiation

Global Warming Potential

gases that absorb infrared energy

gases with a high number of carbon-fluorine bonds

generally have a long atmospheric lifetime

Page | 41

Appendix B: Usage and Application of Refrigeration Process.

Refrigeration can serve us from the cradle to the grave. For some, the benefits starts at birth in

the air condition delivery room and for a few in the modern incubator and nursery for premature

babies. Applications are then encountered and appreciated though the often indirectly

throughout life and for some, refrigeration is even applied after death in cooling the slab vault

at the city morgue. The applications may be classified into one of the following five general

groups. They are as follows:

1. Domestic Refrigeration

2. Commercial Refrigeration

3. Industrial Refrigeration

4. Marine and Transportation Refrigeration

5. Air-Conditioning Refrigeration

1. Domestic Refrigeration: Domestic refrigeration is rather limited in scope, being

concerned primarily with household refrigerator and home freezers. However, because the

number of units in service is quite large, domestic refrigeration represents a significant

portion of the refrigeration industry. Domestic units are usually small in size having

horsepower ratings of between 1/20 and 1/2 horsepower and were of the hermetically sealed

type. Since these applications are familiar to everyone.

2. Commercial Refrigeration: Commercial refrigeration is concerned with the designing,

installation and maintenance of refrigerated fixtures of the type used by retail stores,

restaurants, hotels and institutions for the storing, displaying, processing and dispensing of

perishable commodities of all types.

3. Industrials Refrigeration: Industrial application is larger in size than commercial

application. Typical industrial application is ice plants, large food packing plants that were

fish, meat, poultry, frozen foods etc.

4. Marine and Transportation Refrigeration: Marine refrigeration, of course, referrers to

refrigeration aboard marine vessels and included, for example, refrigeration for boats and

for vessels transporting perishable cargo as well as refrigeration for the ships stores on

Page | 42

vessels of all kinds. Transportation refrigeration is concerned with refrigeration equipment

as it is applied to trucks, both long distance transports and local delivery and to refrigerated

railway cars.

5. Air-Conditioning Refrigeration: Air conditioning applications are of two types, either

comfort or industrial, according to the purpose. Any air-conditioning, which has as its

primary function the conditioning of air for human comfort is called comfort air-

conditioning. Typical installations of comfort air conditioning are in homes, schools,

offices, churches, hotels, retail stores, public buildings, factories, automobiles, busses,

trains, planes, ships etc. The applications of industrial air conditioning are almost without

limit both in number and in variety. Generally speaking, the functions of industrial air

conditioning systems are to

Control the moisture content of hydroscopic materials

The govern rate of chemical and bio-chemical reactions

Limit the variations in the size of precision manufactured articles because of thermal

expansion and construction

Provide clean, filtered air, which was often essential to trouble free operation and to the

production of quality products.

In spite of some specific classifications would include as follows:

Oil refining and synthetic rubber manufacturing

Creation of artificial atmospheric conditions

Medical and Surgical aids

Heat Pump

Ice making

Page | 43

Appendix C: Other Refrigeration Processes (Modification)

1. Cascade refrigeration systems

Some industrial applications require moderately low temperatures, and the temperature range

they involve may be too large for a single vapor compression refrigeration cycle to be practical.

A large temperature range also means a large pressure range in the cycle and a poor

performance for a reciprocating compressor. One way of dealing with such situations is to

perform the refrigeration process in stages, that is, to have two or more refrigeration cycles that

operate in series. Such refrigeration cycles are called cascade refrigeration cycles.

Figure 15. A two-stage cascade refrigeration system with the same refrigerant in both

Refrigerants with more desirable characteristics can be used in each cycle. In this case, there

would be a separate saturation dome for each fluid, and the T-s diagram for one of the cycles

would be different. Also, in actual cascade refrigeration systems, the two cycles would overlap

somewhat since a temperature difference between the two fluids is needed for any heat transfer

to take place. It is evident from the T-s diagram in Fig.16 that the compressor work decreases

and the amount of heat absorbed from the refrigerated space increases as a result of cascading.

Page | 44

Therefore, cascading improves the COP of a refrigeration system. Some refrigeration systems

use three or four stages of cascading.

The characteristics of a cascade refrigeration system are following:

combined cycle arrangements

two or more vapor compression refrigeration cycles are combined

used where a very wide range of temperature between TL and TH is required

the condenser for the low temperature refrigerator is used as the evaporator for the high

temperature refrigerator

2. Multistage compression refrigeration systems

In case of using same refrigerant, then we have the option to mix the refrigerant of each system

with each other to attain better heat transfer properties. These type of systems are called

multistage compression refrigeration systems. In order to understand the behavior, we will

consider 2 stage refrigeration system.

Figure 16. A Multistage compression refrigeration systems

Page | 45

By looking at the T-s diagram of the system, we can clearly see that the refrigerant expands in

the first expansion valve to the flash chamber pressure, the same pressure which the interstage

compressor have. At the time of doing compression, part of the liquid gets evaporated

represented as state 3 and mixed with superheated vapors come from low pressure

compressor at state 2. When the mixture is prepared in the chamber then it will enter in the

high pressure compressor. The saturated liquid state then expands in the second expansion

valve where it further picks up the heat from refrigerated space.

Because of using flash chamber which further do direct mixing process of the refrigerant, we

can relate it with the regeneration process where we extract heat from one process of the cycle

and then delivers the same amount of heat to the other process in the same cycle.

3. Multipurpose refrigeration systems

There are many practical applications in which we require refrigerating effect at more than one

temperature. So to attain this phenomenon either we can do throttling process by installing the

separate throttling valve or to install compressor for each evaporator having unique

temperatures. But the installation of either systems will be too bulky and uneconomical,

therefore we need to make this system much more efficient and economical. For this reason,

we redirect the route of all exit streams from each evaporator to the single compressor.

In order to understand the behavior, we consider ordinary refrigerator freezer unit usually

installed in the houses. Normally the temperature of the freezer compartment is 18C but to

do heat transfer, the refrigerant temperature should be 25C.

Figure 17. A Multipurpose refrigeration systems

Page | 46

Now if we have single expansion valve and evaporator then the same refrigerant will pass

through both freezer compartment and then to the evaporator coils where ice formation will

start. But to reduce the problem of evaporator coil freezing, we can throttle it to the minimum

pressure so that we can use it in the freezer compartment. From where it is then compressed by

single compressor to the condenser pressure.

4. Liquefaction of gases

Another way of improving the performance of a vapor-compression refrigeration system is by

using multistage compression with regenerative cooling. The vapor-compression refrigeration

cycle can also be used to liquefy gases after some modifications.

Figure 18. Vapor-compression refrigeration system is by multistage compression with

regenerative cooling.

Page | 47

5. Gas Refrigeration Systems

The power cycles can be used as refrigeration cycles by simply reversing them. Of these, the

reversed Brayton cycle, which is also known as the gas refrigeration cycle, is used to cool

aircraft and to obtain very low (cryogenic) temperatures after it is modified with regeneration.

The work output of the turbine can be used to reduce the work input requirements to the

compressor. Thus, the COP of a gas refrigeration cycle is

Figure 19. Gas Refrigeration Systems

6. Absorption Refrigeration Systems

Another form of refrigeration that becomes economically attractive when there is a source of

inexpensive heat energy at a temperature of 100 to 200 is absorption refrigeration, where the

refrigerant is absorbed by a transport medium and compressed in liquid form. The most widely

used absorption refrigeration system is the ammonia-water system, where ammonia serves as

the refrigerant and water as the transport medium. The work input to the pump is usually very

small, and the COP of absorption refrigeration systems is defined as

Page | 48

Figure 20. Absorption Refrigeration Systems

7. Thermoelectric Refrigeration Systems

A refrigeration effect can also be achieved without using any moving parts by simply passing

a small current through a closed circuit made up of two dissimilar materials. This effect is

called the Peltier effect, and a refrigerator that works on this principle is called a thermoelectric

refrigerator.

The thermoelectric device, like the conventional thermocouple, uses two dissimilar materials.

There are two junctions between these two materials in a thermoelectric refrigerator. One is

located in the refrigerated space and the other in ambient surroundings. When a potential

difference is applied, as indicated, the temperature of the junction located in the refrigerated

Page | 49

space will decrease and the temperature of the other junction will increase. Under steady-state

operating conditions, heat will be transferred from the refrigerated space to the cold junction.

The other junction will be at a temperature above the ambient, and heat will be transferred from

the junction to the surroundings. A thermoelectric device can also be used to generate power

by replacing the refrigerated space with a body that is at a temperature above the ambient.

Figure 21. Thermoelectric Refrigeration Systems

Marking scheme: Formal Report on Study of a Refrigeration Unit

Name: Md. Hasib Al Mahbub

Student number: 0902045

Section and marks allocated Marks

Summary (10)

Introduction (5)

Theory (10)

Experimental setup (10)

Observed data (5)

Calculated data (5)

Sample calculation (5)

Graphs (15)

Results and Discussions (10)

Conclusion (5)

References and Nomenclature (10)

Overall (10)

Total (100)

ChE 302 Chemical Engineering Laboratory II

PERFORMANCE EVALUATION SHEET

Experiment No : 7 Group No : 03 (A2)

Name of Experiment : STUDY OF A REFRIGERATION UNIT

Following is the list of contributions each of the members of the group conducted while

performing the experiment:

Student

Number

Contribution

Experiment Report

0902041 Has drawn the experimental

setup and observed all data

Has drawn Graphs in Microsoft

Excel

0902042 Has done Calculation Has done sample calculation in

Microsoft word

0902043 Has observed all temperatures

of evaporator and condenser

Has done all calculations in

Microsoft Excel

0902044 Has observed all other

temperature of system, water

flow rate, pressure

Has tabulated all observed and

calculated data in Microsoft word

0902045 Has collected all observed data

in tabulated form

Has drawn graphs and all other

necessary work necessary for

creating a formal report

I hereby announce that every statement I provided above is true and I will be responsible for

any misinformation.

Sign above the line

Name (Group Leader): Md. Hasib Al Mahbub

Student Number: 0902045

CoverTopSummarypage 1-12Figure 1Figure 2page 15-43Marking schemeEvolution

Study of a Refrigeration Unit (R633)

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