SOLAR ABSORPTION DOMESTIC REFRIGERATION

SYSTEM

CAPSTONE PROJECT

Submitted in Partial Fulfillment of the

Requirement for Award of the Degree

Of

BACHELOR OF TECHNOLOGY

In

MECHANICAL ENGINEERING

VIKAS TIWARI (11107080)

RAHISH KUMAR SAHA (11105204)

MOHAN LAL SAHU (11100839)

ANUPAM DWIVEDI (11105812)

Under the Guidance of

Mr. ASHISH KUMAR PATEL

DEPARTMENT OF MECHANICAL ENGINEERING

LOVELY PROFESSIONAL UNIVERSITY

PHAGWARA, PUNJAB (INDIA) -144411

2015

i

Lovely Professional University Jalandhar, Punjab

CERTIFICATE

I hereby certify that the work which is being presented in the Capstone

project/Dissertation entitled “SOLAR ABSORPTION DOMESTIC REFRIGERATION

SYSTEM” in partial fulfillment of the requirement for the award of degree of Bachelor

of technology and submitted in Department of Mechanical Engineering, Lovely

Professional University, Punjab is an authentic record of my own work carried out during

period of Capstone/Dissertation under the supervision of Mr. ASHISH KUMAR

PATEL(Asst. Prof.) Department of Mechanical Engineering, Lovely Professional

University, Punjab.

The matter presented in this dissertation has not been submitted by me anywhere for

the award of any other degree or to any other institute.

This is to certify that the above statement made by the candidate is correct to best of

my knowledge.

Date: ….. APRIL, 2015 Mr. ASHISH KUMAR PATEL

(Asst. Prof.)

Supervisor

The B-Tech Capstone project/ M-Tech Dissertation examination, has been held on

Signature of Examiner

ii

ACKNOWLEDGEMENT

The satisfaction that accompanies the successful completing of any task would be

incomplete without mentioning names of people whose ceaseless co-operation made the task

possible. Their constant guidance and encouragement plays a much important role in

successful completion of this Capstone project. Making capstone project at LPU gave a good

practical experience to us. We would like to express my regards to all my seniors & fellow

trainees who supervised us in one or another way. So, at the outset we express my deep sense

of gratitude to Mr. ASHISH KUMAR PATEL (Mentor) and other staff members who have

been the perennial source of inspiration and guidance in the completion of this project.

iii

TABLE OF CONTENTS

Contents Page No.

Certificate i

Acknowledgement ii

Abstract v

1. Introduction……………………………….………………….……1

2. Review of Literature………………………….…………….….…..3

3. Scope of the study……………………………….…….…….……..5

4. Objective and Hypothesis of the study…………….….….………..6

5. Research Methodology…………………………………….……....7

6. Components of Refrigeration……………………………………....8

6.1.1 Absorber…………………………………………………9

6.1.2 Pump…………………………………………………….9

6.1.3 Heat Exchanger…………………………………………10

6.1.4 Generator………………………………………………..11

6.1.4.1 Working of Generator………………………….11

6.1.5 Condenser………………………………………………12

6.1.6 Capillary tube…………………………………………..13

6.1.7 Evaporator……………………………………………...13

6.1.8 DC Battery……………………………………………..14

6.1.9 Solar system……………………………………………15

iv

7 Work plan with Timeline………………………………………..16

8 Expected Outcomes of the study………………………………..17

9. Experimental Work done………………………………………..18

9.1 Working……………………………………………………...18

9.2 Ammonia Water chart……………………………….………...21

9.2.1 Data obtained from graph………………………………22

9.3 Calculation…………………………………………….………24

9.3.1 Calculation of Heat…………………………………….24

9.3.2 Calculation of COP…………………………………….25

9.3.3 Calculation for Pump…………………………………..26

9.3.4 Calculation for Capillary tube………………………….27

9.3.5 Calculation for Heat Exchanger………………………..32

9.4 Specification of Components……………………………..……34

10. Result and Discussion………………………………………….37

11. Conclusion……………………………………………………..38

12. References……………………………………………………...39

13. Approved project topic in the prescribed format…………………40

v

TABLE OF FIGURE

List of figure Page No.

6.1 Absorber…………………………………………….…………….9

6.2 Centrifugal pump……………………………….………………..10

6.3 Heat Exchanger………………………………….……………….11

6.4 Generator………………………………………….……………...12

6.5 Condenser……………………………………….………………..12

6.6 Capillary tube…………………………………………………….13

6.7 Evaporator………………………………………………………..14

6.9a Solar panel………………………………………………………15

6.9b Components of solar power system……………………………..15

9.1 Circuit diagram VARS system…………………………………...20

9.2 Ammonia Water chart……………………………………………21

9.3 Ammonium hydroxide…………………………………………...36

vi

ABSTRACT

For past few decades, energy has played a prominent role in the development of

technology and economy. Energy has now become inevitable factor for production as well.

The objective of this project is to develop an environment friendly vapour absorption system.

Vapour absorption system uses heat energy, instead of mechanical energy as in vapour

compression system, in order to change the condition of refrigerant required for the operation

of the cycle. R 717(NH3) and water are used as working fluids in this system. The basic idea

of this project is derived from the solar heating panel to obtain heat energy, instead of using

any conventional source of heat energy. In this project various observations are done by

varying operating conditions related to heat source, condenser, absorber and evaporator

temperatures. The drawback of this system is that, it remains idle in the cloudy weather

conditions.

Keyword: - Absorber, Condenser, Capillary tube, Dc battery, Evaporator, Generator, Heat

exchanger, Pump, Solar panel

1

CHAPTER-1

INTRODUCTION

Refrigeration is defined as the process of achieving and maintaining a temperature

below that of the surroundings, the aim being to cool some product or space to the required

temperature. One of the most important applications of refrigeration has been the

preservation of perishable food products by storing them at low temperatures. Refrigeration

systems are also used extensively for providing thermal comfort to human beings by means

of air conditioning.

The subject of refrigeration and air conditioning has evolved out of human need for

food and comfort, and its history dates back to centuries.

Vapour Absorption Refrigeration Systems (VARS) belong to the class of vapour

cycles similar to vapour compression refrigeration systems. However, unlike vapour

compression refrigeration systems, the required input to absorption systems is in the form of

heat. Hence these systems are also called as heat operated or thermal energy driven systems.

Since conventional absorption systems use liquids for absorption of refrigerant, these are also

sometimes called as wet absorption systems. Similar to vapour compression refrigeration

systems, vapour absorption refrigeration systems have also been commercialized and are

widely used in various refrigeration and air conditioning applications. Since these systems

run on low-grade thermal energy, they are preferred when low-grade energy such as waste

heat or solar energy is available. Since conventional absorption systems use natural

refrigerants such as water or ammonia they are environment friendly.

The development of refrigeration and air conditioning industry depended to a large

extent on the development of refrigerants to suit various applications and the development of

various system components. At present the industry is dominated by the vapour compression

refrigeration systems, even though the vapour absorption systems have also been developed

commercially. The success of vapour compression refrigeration systems owes a lot to the

development of suitable refrigerants and compressors. The theoretical thermodynamic

efficiency of a vapour compression system depends mainly on the operating temperatures.

However, important practical issues such as the system design, size, initial and operating

costs, safety, reliability, and serviceability etc. depend very much on the type of refrigerant

and compressor selected for a given application.

The power from the sun intercepted by the earth is approximately 1.8 ×1011 MW

which is much larger than the present consumption rate on the earth of all commercial energy

sources. Thus, in principle, solar energy could supply all the present and future energy needs

of the world on the continuing basis. This makes it one of the most promising of the

2

unconventional energy sources. In addition to its size, solar energy has two other factors in its

favour. First unlike fossil fuels and nuclear power, it is an environmental clean source of

energy. Second, it is free and available in adequate quantities in almost all parts of the world

where people live. So it can prove very economical to use solar energy for refrigeration and

air conditioning system. The change done in this project is the change in the mode of

obtaining energy for generator in vapour absorption system. By producing an adsorption

refrigeration system we are not only cutting down the energy costs but also preserving our

environment. This refrigeration system doesn’t use any of the CFCs so our ozone layer is

safe. Greenhouse gases and their damaging effects on the atmosphere have received increased

attention following the release of scientific data by United Nations Environment Programme

and World Meteorological Organization that show carbon dioxide to be the main contributor

to increased global warming. The domestic refrigerator-freezers operating on alternative

refrigerants such as HFC-134a, contribute indirectly to global warming by the amount of

carbon dioxide produced by the power plant in generating electricity to operate over a unit

over its lifetime. This contribution is nearly 100 times greater than the direct contribution of

the refrigerant alone.

Moreover, approximately 62 million mew units are being manufactured worldwide

every year, and hundreds of millions are currently in. use. It is anticipated that the production

of refrigerator-freezers will substantially increase in the near future as a result of the

increased demand, especially in the developing countries. Therefore, in response to global

concerns over greenhouse resorts are being made to produce refrigerator-freezers with low

energy consumption.

3

CHAPTER-2

LITERATURE REVIEW

An extensive review of the literature has been done on vapour absorption

refrigeration. The main idea was to have possible future direction of research, with the aim of

obtaining fundamental understandings of solar absorption systems and to gain useful

guidelines regarding designs parameters as applied in both air-conditioning and refrigeration.

A large number of researchers have carried out research in the field of vapor absorption

refrigeration using different working pairs and the most common working pairs are LiBr-

H2O and NH3-H2O.

1. Solar absorption refrigeration (October 30, 1990)

Tyagi carried out the detailed study on aqua-ammonia VAR system and

plotted the coefficient of performance, mass flow rates as a function of operating

parameters i.e. absorber, evaporator and generator temperatures. He showed that COP

and work done are the function of evaporator, absorber, and condenser and generator

temperature and also depends on the properties of binary solution.

2. Aqua-ammonia absorption refrigeration (June 24, 1994)

Gogus showed the irreversibility’s in components of aqua-ammonia

absorption refrigeration system by second law analysis. They calculated the

dimensionless exergy loss of each component, exergetic coefficient of performance,

coefficient of performance and circulation ratio for different generator, absorber

evaporator and Condenser temperature. They concluded that aqua-ammonia system

needs a rectifier for high ammonia concentrations but it will lead to additional exergy

loss in the system. They observed the highest exergy loss in evaporator followed by

absorber. I was also concluded that the dimensionless total exergy loss depends on

generator temperature.

3. Ammonia water absorption refrigeration system (June 21, 2005)

Sozen studied the effect of heat exchangers on the system performance in an

ammonia water absorption refrigeration system. Thermodynamic performance of the

system is analyzed and the irreversibility’s in the system components have been

determined for three different cases. The COP, circulation ratio, and non dimensional

exergy loss of each component of the system is calculated. They concluded that the

evaporator, absorber, generator, mixture heat exchanger and condenser show high

non-dimensional exergy losses. They also concluded that using refrigerant exchanger

in addition to mixture heat exchanger does not increase the system performance.

4

4. Solar water cooler (August 21, 2007)

Fernandez-Seara and Vazquez studied the optimal generator temperature in

single stage ammonia – water absorption refrigeration system. They studied the

behavior of this temperature on thermal operating conditions and system design

parameters. They carried out study based on parametric analysis by developing a

computer program and based on the results designed a control system. The control

system developed maintains a constant temperature for the space to be refrigerated

and also control the optimal temperature in the system generator.

5. Vapour absorption refrigeration (May 12, 2008)

Yamankaradeniz performed calculations for a 10kW cooling load system. The

evaporator and condenser temperature was taken as 4oC and 38oC respectively. The

generator temperature was taken as 90oC. Effectiveness of solution heat exchanger

was assumed as 0.5 and efficiency of pump was assumed equal to 0.9. They

concluded that entropy generation of the generator is an important fraction of the total

entropy generation in the system basically due to the temperature differences between

25 the heat source and the working fluid and in order to decrease the total entropy

generation of the system, the generator should be developed.

5

CHAPTER-3

SCOPE OF THE STUDY

The prices of energy have been increasing exponentially worldwide. Industrial

Refrigeration is one of the most energy consuming sector. What if a refrigeration system is

designed which uses no energy or minimal amount of energy?

In the present times, the conventional sources of energy are depleting rapidly. Then these

sources may not available in future. This demands increase the price of conventional energy.

The only way to reduce the consumption of these sources of energy as well as to fulfil the

demands of the ever increasing population is shift to the renewable source of energy, such as

solar energy.

By producing an adsorption refrigeration system we are not only cutting down the energy

costs but also preserving our environment. This refrigeration system doesn’t use any of the

CFCs so our ozone layer is safe.

This invention can improve refrigerating unit, raise coefficient of performance, reduce

energy cost of refrigerating unit and has notably social and economic benefit.

6

CHAPTER-4

OBJECTIVE & HYPOTHESIS OF THE STUDY

The main objective of Solar Refrigerator system is given below-

To improve the COP of the adsorption/absorption refrigerator to make it more

attractive for usage.

To reduce the size of the assembly by making it more compact.

Cost is the biggest barrier in implementation of absorption refrigeration. We aim to

minimize it as far as possible.

The absorption/adsorption refrigeration system is too bulky. Its weight reduction is

also one of the aims. It can be reduced by using other materials.

Till date absorption refrigeration is limited for industrial purposes. We aim to make it

available for mass rural use as stated above in small capacities by using solar

absorption.

7

CHAPTER-5

RESEARCH METHODOLOGY

1. Selection of the project as it has vast scope in future.

2. Selection of raw material for different component.

3. Design and selection of different components.

4. Setup of base of the whole arrangement was done.

5. Different components of the system were prepared.

6. Mathematical modelling of generator, absorber, heat exchanger and condenser was done.

7. Assembly of different component were done by brazing.

8. Ammonia was made to flow through the system.

9. Observations were taken.

10. Calculation and successful results were obtained.

8

CHAPTER-6

COMPONENTS USED IN SOLAR ABSORPTION

REFRIGERATION SYSTEM

I. ABSORBER

II. PUMP

III. HEAT EXCHANGER

IV. GENERATOR

V. SOLAR PANEL

VI. CONDENSER

VII. CAPILLARY TUBE

VIII. EVAPORATOR

IX. DC BATTERY, INVERTER

The detailed explanation given below-

6.1.1 ABSORBER

Absorber in absorption system is used to store the mixture of water and ammonia in

particular proportion. It is actually a box which has three ports. First port connects the pump

to the absorber. Second port connects the capillary tube to the absorber. Third port connects

the evaporator to the absorber. It is kept at the lowest position in the system.

Heat is dissipated from the absorber as shown in the below diagram. It is important

that the temperature of absorber should be kept low so that the vapour of ammonia can get

mixed with the water, coming from the generator through throttle valve, thus producing the

aqua ammonia solution. This aqua ammonia solution is then pump to the generator with the

help of pump as shown in the above diagram.

9

Fig 6.1 Absorber

6.1.2 PUMP

A pump is a device that moves fluids (liquids or gases), or sometimes slurries, by

mechanical action. In the absorption system, the compressor is replaced by an absorber which

dissolves the refrigerant in a suitable liquid, a liquid pump which raises the pressure and a

generator which, on heat addition, drives off the refrigerant vapour from the high-pressure

liquid. Some work is needed by the liquid pump but, for a given quantity of refrigerant, it is

much smaller than needed by the compressor in the vapour compression cycle. In an

absorption refrigerator, a suitable combination of refrigerant and absorbent is used. The most

common combinations are ammonia (refrigerant) with water (absorbent). Generally in the

absorption system pump work is negligible.

10

Fig 6.2 centrifugal pump

6.1.3 HEAT EXCHANGER

A heat exchanger is equipment built for efficient heat transfer from one medium to

another. The heat exchanger provided between the pump and the generator is used to cool the

weak hot solution returning from the generator to the absorber. The heat removed from the

weak solution raises them temperature of the strong solution leaving the pump and going to

generator. This operation reduces the heat supplied to the generator and the amount of

cooling required for the absorber. Thus the economy of the plant increases.

Generally shell and tube type heat exchanger are used for better effectiveness, where

hot and cold fluid flow in opposite to each other.

Figure of heat exchanger is given next,

11

Fig 6.3 Heat exchanger

6.1.4 GENERATOR

This is unit of a system which separates the dissolved ammonia from the water-

ammonia solution. It has a heating coil inside it. The purpose of heating coil is to heat the

mixture up to a boiling temperature of ammonia solution. Since boiling point of ammonia

solution is lower than the boiling point of water, the ammonia gets converted into vapour and

water remains in its liquid state. It is not possible to separate ammonia solution from water

completely; therefore we use rectifier for achieving 99 percent separation of ammonia vapour

from solution.

6.1.4.1 Working of Generator-

In generator we have a coil through which current is passed. Due to current heat is

generated in the generator. The temperature is maintained so as to vaporize the ammonia and

thus separating ammonia from strong solution of aqua-ammonia. For getting 99 percent of

pure ammonia in form of vapour, we are required to use analyser and rectifier. In present

project we are using only simple generator without any analyser. Electricity required by

heating coil we be obtained from the solar panel. Generator has pressure greater than

absorber. Therefore it is required to increase the pressure of the strong aqua-ammonia

solution so that it can be transferred to the generator, and this is obtained with the help of the

12

liquid pump. Once the strong aqua-ammonia solution reaches the generator, it is heated and

the liquid ammonia present in strong aqua-ammonia solution is converted into vapour. These

ammonia vapours then move towards the condenser due to pressure difference between the

generator and condenser. The weak solution, after the separation of ammonia vapour, is then

transferred to the absorber.

Fig 6.4 Generator

6.1.5 CONDENSER

A condenser is a device or unit used to condense a substance from its gaseous to

its liquid state, typically by cooling it. In so doing, the latent heat is given up by the

substance, and will transfer to the condenser coolant. Condensers are typically heat

exchangers which have various designs and come in many sizes ranging from rather small

(hand-held) to very large industrial-scale units used in plant processes.

13

Fig 6.5 Condenser

6.1.6 CAPILLARY TUBE

Capillary tube is an expansion device having very narrow diameter. This device

connects between condenser and evaporator to reduce the pressure or for expansion process

at constant enthalpy. Due to this refrigerant comes to saturation states and able to extract heat

from cabin in evaporator.

Another capillary tube is used in between generator and absorber in vapour absorption

refrigeration system for the same purpose to reduce the pressure.

Fig 6.6 Capillary tube

14

6.1.7 EVAPORATOR

An evaporator is a device used to turn the liquid into its gaseous form. The liquid is

evaporated, or vaporized, into a gas.

In evaporator low temperature, low pressure refrigerant extract the heat from the cabin or

system which we have to cool.

It is in the evaporators where the actual cooling effect takes place in the refrigeration.

The evaporators are heat exchanger surfaces that transfer the heat from the substance to be

cooled to the refrigerant, thus removing the heat from the substance. The evaporators are used

for wide variety of diverse applications in refrigeration and air conditioning processes and

hence they are available in wide variety of shapes, sizes and designs.

Fig 6.7 Evaporator

6.1.8 DC BATTERY

Direct current is the unidirectional flow of electric charge. Direct current is produced

by sources such as batteries, thermocouples. Here battery is used to power the pump and

15

another battery and inverter set up to powered the heater inside generator. Battery is

charged by solar system, which produces dc power and this dc power converted into ac by

using inverter.

6.1 .9 SOLAR SYSTEM

A solar cell, or photovoltaic cell, is an electrical device that converts the energy

of light directly into electricity by the photovoltaic effect. It is a form of photoelectric cell,

defined as a device whose electrical characteristics, such as current, voltage, or resistance,

vary when exposed to light. Solar cells are the building blocks of photovoltaic modules,

otherwise known as solar panels.

Fig 6.9a Solar panel

As solar radiation is irradiance on solar panel dc power is generated by photovoltaic effect

and this power is regulated or controlled by regulator. For ac supply this dc power must be

change into ac power by using inverter.

16

Fig 6.9b components of solar power system

17

CHAPTER-7

WORK PLAN WITH TIMELINE

S.N ACTIVITY START

DATE

END DATE

1. Selection of design parameter of the project 16th march 20th march

2. Selection of condenser as per requirement 21st march 21st march

3. Selection of evaporator as per requirement 23rd march 23rd march

4. Calculation and selection of pump 24th march 27th march

5. Calculation and selection of capillary tubes 25th march 2nd April

6. Preparation of absorber and generator box 24th march 26th march

7. Calculation and preparation of heat exchanger 28th march 5th April

8. Calculation of heat required and selection of heater 1st April 4th April

9. Selection of battery, inverter 5th April 5th April

10. Assembly of all components of project in a circuit 7th April 12th April

11. Observation of project 15th April 15th April

18

CHAPTER-8

EXPECTED OUTCOMES OF THE STUDY

The outcome of the project will be a working prototype of an NH3/water

based absorption refrigerator designed for rural application.

The construction of the assembly is relatively simple and we are sure will not take much

time. Keeping the objective of the project in mind we will be stressing upon the design and

idea part to enhance the learning experience and improving the efficiency and portability of

the system.

As per our design expected capacity of the refrigerator is 0.15TR and expected COP will be

1.53.

19

CHAPTER-9

EXPERIMENTAL WORKDONE

9.1 WORKING

1-2

Solution of ammonia is heated to generate ammonia vapour, which is transferred to the

condenser. In condenser ammonia vapour is cooled by air and vapour ammonia changes to

ammonia liquid.

2-3

After condenser liquid ammonia is passed through narrow capillary tube where pressure

reduces from 14bar to 5bar.

3-4

Saturated liquid ammonia at low pressure comes to evaporator, where it extract the heat from

cabin or system which we have to cool. After extracting heat liquid ammonia become vapour

again.

4-5

Ammonia vapour is then transferred to absorber where it is absorbed by water as absorber

and form strong solution of ammonia called ammonium hydroxide.

5-6

Strong solution of ammonia then pumped to generator by pump.

6-7

Heat exchanger connected between absorber and generator extracts the heat of coming weak

solution and give to strong solution.

20

7-1 and 7-8

Strong solution coming from absorber is then heated up to 90 degree Celsius. Ammonia

vapour then passes through rectifier and transferred to condenser again.

And weak solution of ammonia comes back to absorber again.

8-9

In heat exchanger heat of weak solution transferred to strong solution of ammonia so that it

will preheat before generator.

9-10

High pressure refrigerant in generator is reducing to low pressure by another capillary tube

before absorber.

21

22

9.2 AMMONIA WATER CHART

23

9.2.1 FROM GRAPH OBTAINED DATA

Calculation for Pump:-

State 1- saturated vapour state at =14 bar, C=1

= C, =1700 kj/kg

State 2- saturated liquid at =14 bar, C=1

= C, =500kj/kg

State 3- isenthalpic process: - at C=1, =5bar

= C, = =500 kj/kg

State 4- saturated vapour at =5 bar, C=1

=1660 kj/kg

State 5- From absorber (strong solution) at P=5bar

= C, C=0.53, =70 kj/kg

State 6- After pump, negligible enthalpy change

Therefore =

State 7-after heat exchanger, =200kj/kg

State 8-P=14 bar, =305 kj/kg

State 9- =150 kj/kg

State 10- = =150 kj/kg

=-190 kj/kg

=1790 kj/kg

(Weak) = 0.42

24

(Strong) = 0.53

Concentration:-

0.98

0.42

0.53

Pressure:-

Bar (Condenser pressure)

5 Bar (Evaporator pressure)

Mass flow rate:-

0.0271 kg/min.

0110 kg/min.

0.137 kg/min.

25

9.3 CALCULATIONS

Refrigerant: - (Ammonia)

Boiling point = C

Melting point = C

Specific gravity= 0.91

Solubility in o = 47% at C

31% at C

18% at C

Absorbent: - o (water)

Boiling point = C

Density = 1000kg/m3

9.3.1 Calculation of heat

Assume capacity=0.15TR

Heat extracted by Evaporator:-

= 0.0271 kg/min.

= ( ) = 0.15 210 = 31.5 kj/min.

Heat removed by condenser:-

= ( ) =32.52 kj/min.

Heat removed on absorber:-

= ( ) =50.135 kj/min.

Heat given in Generator:-

26

= ( ) =53.658 kj/min.

Again =894.3 watt

Heater of 894.3 watt is required for generator.

9.3.2Coefficient of performance:-

Actual COP: - = = 0.587

Theoretical COP: - = = 1.53

At absorber

By using equations

Or,

&

Then,

-----eq. (1)

& 0.0265= --------eq. (2)

From eq. (1) & eq. (2)

We get,

=0.137 kg/min.

=0.110 kg/min.

27

For :-

By using formula

&

From the refrigeration table

At 5 bar = 0.001096

At 5 bar = 0.00158

=0.00127 /kg

= 70+ = 71.104 kj/kg

9.3.3 Power consumed by pump:-

P =

Then, P = = 0.0025 kW

P=2.52 watt

Assume efficiency =0.7

Then Power required to pump =3.6 watt

9.3.4 Tube design:-Capillary

For capillary 1

Diameter of capillary tube, D = 0.914 mm

28

Area of cross section, A = 0.000000486

From the refrigeration table

AT 14 BAR

Viscosity of ammonia

=116 Ns/

Specific volume of ammonia

=1.71

Mass flow rate of ammonia

=0.0271kg/min. = 0.0004516kg/sec.

G = = 927.88

Then velocity at entrance of capillary tube

=G =1.585 m/sec.

Now, Reynold number

= =6295.18 ….eq (i)

Then, friction factor

= =0.036 ….eq (ii)

Enthalpy at entrance of the capillary tube

=357.25kj/kg

AT 5 BAR

From refrigeration table

29

Various parameters of ammonia at liquid and vapour states

= 171.63 kj/kg

= 1269.45 kj/kg

= 0.174 Ns/

= 0.00916 Ns/

Now,

…..eq (a)

Dryness fraction

X= 0.146

Now, at exit of capillary tube

Similarly by using formula as eq (a)

Specific volume

Velocity at exit

44.18 m/sec

Viscosity:-

Similarly by using formula as eq (a)

Ns/

And friction factor

30

By using equation i and ii

Now,

Change in pressure = P0-P1

= 9 Ns/

Change in velocity = u1-u0

=42.6 m/s

Average velocity

u= =22.88 m/sec.

Average fiction factor

f= =0.037

Now, Length of capillary tube

By using formula,

L= =1.72m.

L = 5.6 ft

For capillary 2

=0.11kg/min. = 0.00183kg/sec.

G = 3771.6 kg/m2s

From refrigeration table

At :-

31

Specific volume

=0.00121

Then velocity at entrance

= G =4.5 m/sec

Viscosity,

= 0.45 Ns/ , 0.098 Ns/

At concentration 0.42

=0.42 ( ) +0.58 ( )

= 0.302 Ns/

And, friction factor

By using equation i and ii

=0.032

At 4 bar & at concentration 0.42

From refrigeration table

Specific volume

= 0.00158 , = 0.001

0.42 ( ) +0.58 ( ) = 0.0012436

Then velocity at exit

= G = 4.7 m/sec

Viscosity.

= 0.153 Ns/ , 1 Ns/

32

Then, by using above equation

= 0.644 Ns/

And friction factor

By using eq i and ii

= 0.038

Now,

Change in pressure P0-P1 =9bar

Change in velocity

=0.2 m/s

Average velocity

u= =4.6 m/sec

Average friction factor.

f = 0.035

Then Length of capillary tube

By using formula

L= =2.3m. =7.5ft

9.3.5 Design of heat exchanger:-

From our design data

Temp of hot fluid at inlet

33

Temp of hot fluid at exit

Temp of cold fluid at exit

Temp of cold fluid at inlet

Now, Q1= Th1-Tc1

Q2= Th2-Tc2

For calculation of LMTD

By using equation

Qm = (Q1- Q2)/lnQ1/Q2

Then = =294.5 k

Heat transferred in heat exchanger,

By using formula

Q = =300 watt

Taking Overall heat transfer coefficient of ammonia solution

U = 80 w/m2.degree

Then,

Q = UA

300 = 80

Length of pipe inside heat exchanger,

l=1.6 m.

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9.4 SPECIFICATION OF PARTS OF THE SYSTEM

1. ABSORBER -

Specification:

Length= 10.16 cm, Breadth= 10.16 cm, Height= 10.16 cm.

Material used: Galvanized iron.

Volume: (1048.77) cm^3

2. GENERATOR-

Specification:

Length= 38.1 cm, Diameter 12.7cm

Material used: Galvanized iron.

Volume: (4826.4) cm^3

It has three ports.

3. CONDENSER

Specification:

Length= 38 cm, Width= 38 cm

Number of turns= 9

Outer diameter of condenser pipe= 5.5mm

4. A. CAPILLARY TUBE

Specification:

Length=1.72 m

Outer diameter= 0.914mm

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B. CAPILLARY TUBE

Specification: Length= 2.3 m

Outer diameter=0.914mm

5. PUMP

Type: Centrifugal pump.

Specification: 4 W, 12V DC

6. Evaporator

Type: evaporator with cabin

Specifications:

Length=76cm, breadth=45cm, height= 25cm

Pipe diameter= 6mm

7. Heat exchanger

Type: Shell and tube

Length =12.7 cm

Inner dia. of shell= 7.6 cm

Outer dia. of shell= 10 cm

Length of pipe= 1.6 m

8. Heater

Type: immersion rod

Power= 500watt

36

9. Battery 1

Specification: 12volt, 7Amp

10. Battery 2

Specification: 12volt, 40Amp

11. REFRIGERANT

Quantity: 1 Litre

Type: R-717(Ammonia Hydroxide- (50%-60%) concentration)

Specific gravity=0.91

Fig 9.1 ammonium hydroxide

37

CHAPTER 10

RESULTS & DISCUSSION

As calculated earlier, the heat input required to run the 0.15TR vapour refrigeration

system, for the operating conditions design is about 900 watt.

For this system the coefficient of performance is also calculated. The result can be

summarized as

Condenser pressure : 14 Bar

Evaporator pressure : 5 Bar

Heat input required : 900 watt

Power of solar panel : 100watt

Theoretical COP : 1.53

Actual COP : 0.58

Evaporator temp : 10 – 20 degree Celsius

The natural cooling arrangement was sufficient. Condensing temperature averaged at 37

degree Celsius

The cold box temperature increased over 10 °C and up to 20 °C during the day phase, thus

the aim of maintaining low temperatures in the chamber was not attained. This comes from

the higher heat gain of the box than expected. An improved box of lower heat losses must be

built in order to improve the results, especial the connection between the condenser and the

evaporator.

Final analysis shows that the process of solar absorption-assisted cooling could be an

alternative for vapour compression system for cold room applications.

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CHAPTER 11

CONCLUSION

This project solar powered vapour absorption refrigeration system is operated by low

grade solar energy, AC supply or any other unconventional low grade energy, so its running

cost will be less. Mainly this project is done for those rural areas where electricity is limited

and for the outside city playground where players can drink cold water.

This project is different is different from today’s refrigerator because refrigerator is normally

run by vapour compression system as high grade energy, which become heavy and bulky due

to compressor used.

By producing an adsorption refrigeration system we are not only cutting down the

energy costs but also preserving our environment. This refrigeration system doesn’t use any

of the CFCs so our ozone layer is safe.

39

REFERENCES

www.iaeng.org/publication/WCE2012/WCE2012_pp2016-2020

By VK Bajpai - 2012.

www.ijetae.com/files/Volume4Issue9/IJETAE_0914_64

By K Karthik.

www.students.iitk.ac.in/ge3/ART%20PI%20copy

By IIT Kanpur.

www.ijates.com/images/short_pdf/1396856289_P10-16.pdf

By International Journal of Emerging Technology and Advanced engineering

September 2014.

“REFRIGERATION AND AIR CONDITIONING” By C P Arora.

Tata McGraw-Hill Education, 01-Jul-2001

“REFRIGERATION AND AIR CONDITIONING” By P L Ballaney

Khanna, 2005.

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APPROVED PROJECT TOPIC IN THE PRESCRIBED

FORMAT

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