i

SOLAR REFRIGERATION

CAPSTONE PROJECT REPORT

in partial fulfillment for the award of the degree

of

BACHELOR OF TECHNOLOGY

IN

MECHANICAL ENGINEERING

Under The Guidance of: Submitted by:

Mr. Vikas Rathore Manoj K.Mallick (11105019)

Assistant Professor (ME) Lokesh Kumar (11107291)

Piyuesh Goyal (11102052)

Puneet (11107785)

Pratik Gupta (11114883)

LOVELY PROFESSIONAL UNIVERSITY

Phagwara144401, Punjab (India)

2015

ii

CERTIFICATE

This is to certify that the Project titled Solar Refrigeration in partial fulfillment of the

requirements for the award of degree of BACHELOR OF TECHNOLOGY and submitted in

Department of Mechanical Engineering , Lovely Professional University , Punjab is a record

of bonafide work done under the supervision and guidance of Sir Vikas Rathore , Assistant

Professor , Department of Mechanical Engineering , Lovely Professional University ,

Punjab.

The contents of this project , in full or in parts , have neither been taken from any other

source nor have been submitted to any other Institute or University for award of any degree

or diploma and the same is certified.

Date : Manoj K. Mallick (11105019)

Lokesh Kumar (11107291)

Piyuesh Goyal (11102052)

Puneet (11107785)

Pratik Gupta (11114883)

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

knowledge.

Date : Mr. Vikas Rathore

Project Supervisor

(Mechanical Department)

iii

ACKNOWLEDGEMENT

Through this acknowledgement we would like to thank our mentor, supervisor and people

who directly as well as indirectly motivated us for the completion of the project. It is

meaningless if we say that we completed this project of our own.

First and foremost we would like to thank our mentor Mr. Vikas Rathore , Assistant

Professor at Department of Mechanical Engineering at Lovely Professional University ,

Punjab. Our mentor who possesses great skills of encouraging, guiding and giving good

suggestions has always given us the freedom to explore the possibilities and has also given us

time at any hour of the day to seek his guidance and presence. We are heartily delighted and

honoured to have our teacher as our mentor for this project.

Secondly we would like to thank our university Head of School, Head of Department and

various teachers including lab assistants who through their practical knowledge and skills

have always given us their precious time when we needed them most.

Also we would like to thank our parents and friends who very selflessly co-operated us at

every phase of this project. No work in our life is possible without the blessings of our

parents and good wishes of our friends. We would like to thank each one of them through

our words and through our thoughts.

Last but not the least we would like to thank god the eternal who is always with us at each

and every phase of our life.

iv

TABLE OF CONTENTS

Contents Page No.

Certificate i

Acknowledgement ii

Table of figures v

Abstract vii

CHAPTER 1

1.1 Introduction..1

1.1.1 Solar energy...1

1.1.2 Current applications of refrigeration.1

CHAPTER 2

2.1 Review of Literature....3

CHAPTER 3

3.1 Scope of the study....4

CHAPTER 4

4.1 Objective and Hypothesis of the study.....6

CHAPTER 5

5.1 Research Methodology.....7

CHAPTER 6

6.1 Components of the solar refrigeration system..8

6.1.1 Galvanized sheet metal.9

6.1.2 Polystyrene..10

6.1.3 DC battery...11

6.1.4 (a) DC fan....12

v

6.1.4 (b) Fan below the holes..12

6.1.5 DC oxygen pump......................................................................................... 13

6.1.6 (a) Aluminium vessel.14

6.1.6 (b) Aluminium vessel over the fan.14

6.1.7 Acetone..15

6.1.8 Sealant16

6.1.9 Solar panel..17

CHAPTER 7

7.1 Work plan with Timeline..18

CHAPTER 8

8.1 Expected Outcomes of the study...19

CHAPTER 9

9.1 Process carried out during the construction..20

9.1.1 Box construction....20

9.1.1 (a) Shearing process20

9.1.1 (b) Snipers..21

9.1.1 (c) V-Bending22

9.1.1 (d) Edge bending22

9.1.1 (e) Refrigerator box23

9.1.1 (f) Internal chamber of the refrigerator box24

9.1.1 (g) Slotted hole to fit the aluminium vessel24

9.1.1 (h) Punched holes for air passage25

9.1.1 (i) Air tight gate for refrigerator .25

9.2 Working of the refrigeration system..27

CHAPTER 10

10.1 Specification of Components...31

vi

CHAPTER 11

11.1 Result and Discussion......34

CHAPTER 12

12.1 Conclusion....35

References....36

Approved project topic in the prescribed format..37

vii

TABLE OF FIGURES

List of figures Page No.

6.1.1 Galvanized sheet metal9

6.1.2 Polystyrene..10

6.1.3 DC battery...11

6.1.4 (a) DC fan....12

6.1.4 (b) Fan below the holes..12

6.1.5 DC oxygen pump......................................................................................... 13

6.1.6 (a) Aluminium vessel.14

6.1.6 (b) Aluminium vessel over the fan.14

6.1.7 Acetone..15

6.1.8 Sealant16

6.1.9 Solar panel..17

9.1.1 (a) Shearing process20

9.1.1 (b) Snipers..21

9.1.1 (c) V-Bending22

9.1.1 (d) Edge bending22

9.1.1 (e) Refrigerator box23

9.1.1 (f) internal chamber of the refrigerator box24

9.1.1 (g) Slotted hole to fit the aluminium vessel24

9.1.1 (h) Punched holes for air passage25

9.1.1 (i) Air tight gate for refrigerator .25

9.2 (a) Block diagram of the refrigeration system..29

9.2 (b) Typical diagram of the refrigeration system30

10.1 Dimensions of the refrigerator.31

viii

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 refrigeration system. The refrigeration

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. Acetone

and air are used as working fluids in this system. The basic idea of this project is derived

from the cooling effect of acetone at it absorbs the heat from any object and gets vapourized.

In this project various observations are done by varying operating conditions related to

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

weather conditions and requires high initial investment which stands as a barrier for

commercializing the solar refrigeration system.

1

CHAPTER 1

1.1 Introduction

Literal meaning of refrigeration is the production of cold confinement relative to its

surroundings. In this, temperature of the space under consideration is maintained at a

temperature lower than the surrounding atmosphere. To achieve this, the mechanical device

extracts heat from the space that has to be maintained at a lower temperature and rejects it to

the surrounding atmosphere that is at a relatively higher temperature.

It is a well-known fact that the spoilage of food and many other items reduces at a

lower temperature. The refrigerator removes unwanted heat from the food products and

throws away that heat to the room the surrounding environment of the refrigerator.

In refrigeration, heat is pumped out from a lower temperature space to a higher

temperature environment.

1.1.1 Solar energy

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

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.

This refrigeration system doesnt use any of the CFCs so our ozone layer is safe.

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.

1.1.2 Current applications of refrigeration

Probably 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. The use of refrigerators in kitchens for storing

fruits and vegetables has allowed adding fresh salads to the modern diet year round, and

storing fish and meats safely for long periods. Optimum temperature range for perishable

food storage is 3 to 5 C (37 to 41 F).

2

i. Condensation of gases

ii. Dehumidification of air

iii. Removal of Heat of Reaction

iv. Control of Fermentation

v. Cooling for preservation

vi. Preservation of Dairy Products

vii. Food storage and distribution

viii. Cold treatment of metals

ix. Medical applications:

3

CHAPTER 2

2.1 REVIEW OF LITERATURE

Solar refrigeration is a useful application in areas of the world with high insulation

levels where there is a demand for cooling and there is not electricity to supply conventional

power systems.

A detailed literature search was conducted to find out what research has been done in

the area of solar assisted cooling, 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.

Solar absorption refrigeration devices are of importance to meet the needs for cooling

requirements such as air-conditioning and ice-making and food preservation in remote areas.

They are also noiseless, non corrosive, and environment friendly. For the latter reasons,

research activities in this sector are on the increase in order to solve the crucial factors which

render these systems not ready to compete with the well-known vapor compression system.

Environmental-friendly means of air conditioning and refrigeration are attracting a lot of

attention nowadays since traditional methods such as vapor compression cycles require

consumption of expensive electric energy and are responsible for emission of green house

gases.

Absorption air conditioning is an attractive alternative to the latter-mentioned

methods. The emphasis when reviewing the research was on the design, evaluation and cost

effectiveness of the prototypes.

4

CHAPTER 3

3.1 SCOPE OF THE STUDY

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.

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?

There is environmental concern regarding conventional refrigeration technologies

including contribution to ozone layer depletion and global warming. Refrigerators which

contain ozone depleting and global warming substances such as chlorofluorocarbons (CFCs),

in their insulation foam or their refrigerant cycle, are the most harmful. By making a solar-

powered refrigerator we are eliminating the use of these harmful gases and save earth from

global warming.

In India what we commonly notice is the abatement in electricity mostly during the

summer days, our project directly uses solar energy to charge up the battery and use that

power for refrigeration. In this way we are going to have the refrigeration effect whole day

even in case of abatement of electricity and thus the probability of wasting food would

gradually decrease.

The study can be further commercialized in rural areas where the people have limited

or no resources for refrigeration or no electricity and also want cheap products for their

comfort; the refrigeration system made in this study uses parts that are generally available at

low price and easily in market.

Making a cheap product that can be used by every household reduces the wastage of

food resources. In India the resources are really limited and thus making it a poor country, by

saving the resources we are also contributing to our society to make it safe and sound.

Problem Statement:

Using a volatile liquid for refrigeration requires a compact closed system. As acetone

is highly inflammable and vaporizes at a very low temperature of 20oC it is very important to

isolate the chemical from the outside environment.

The problem is solved by insulating the body with double layered foam and thus

maintaining the inside temperature of acetone at a lower degree.

5

As the body is made by sheet metal cent percent closed or leak proof container is not

possible to make and acetone being volatile vaporizes and there is a loss in chemical or

wastage.

The solution to this problem is to close every corner by silicon gel to make it air tight

and eliminate the loss of chemical by vaporizing.

As we are using solar panel and using solar energy for power generation, it can work

with full efficiency only on summer days. During winter days the sunlight gets deemed and

there is less power generation.

The problem can be solved using a battery of large capacity and a controller to control

the flow of charge from the battery.

The solar panel requires high initial investment for implanting in houses. It is a barrier

for use by the poor people who are not able to afford the price of solar panels.

6

CHAPTER 4

4.1 OBJECTIVE & HYPOTHESIS OF THE STUDY

The main objective of Solar Refrigerator system is given below:

The main objective of this project is to build a refrigerator which runs on energy

directly provided by sun, and include photovoltaic energy.

The second most important thing to consider is electricity; price of electricity per unit is

increasing day by day. Our project focuses on eliminating the electricity consumption

and use the free source solar energy to power the refrigerator.

Price factor: The project is so designed that it uses the least amount of power and

relatively cheap from the conventional refrigerators.

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

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.

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

minimize it as far as possible.

To make the energy and power free for everyone and every user. Every user in India

can equally use the power resources and lead a comfortable life.

To make a refrigeration system using low grade energy that is renewable and always

available in abundance.

To make a refrigeration system without using compressor or any toxic chemicals like

ammonia.

7

CHAPTER 5

5.1 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 different parts of the container, partition, door etc.

7. Assembly of different parts were done by rivets.

8. The vessel and fan were fixed between the container and holes were made as required

for wiring purpose

9. Acetone was poured in the vessel and the partition was made air tight by silica gel.

10. The pump and the fan were connected to the battery or directly to the solar panel.

11. Observations were taken using thermometer for the reduction in temperature inside the

refrigerator.

12. Successful results and cold object were obtained by the refrigeration system.

8

CHAPTER 6

6.1 COMPONENTS OF SOLAR REFRIGERATION SYSTEM

I. SHEET METAL

II. THERMOCOL (POLYSTYRENE)

III. 12V BATTERY

IV. 12V DC FAN

V. 12V DC OXYGEN PUMP

VI. ALUMINIUM VESSEL

VII. ACETONE

VIII. SEALANT OR SILICA GEL

IX. SOLAR PANEL

For our project we are using the components that are easily available in the market place and

doesnt have much cost. So our prime aim is to lower the price when the components are

taken in consideration,

The detailed explanations of the above component are as follow:

9

6.1.1 SHEET METAL

Sheet metal is metal formed by an industrial process into thin, flat pieces. It is one of

the fundamental forms used in metalworking and it can be cut and bent into a variety of

shapes. Countless everyday objects are constructed with sheet metal. Thicknesses can vary

significantly; extremely thin thicknesses are considered foil or leaf, and pieces thicker than

6 mm (0.25 in) are considered plate.

Sheet metal is available in flat pieces or coiled strips. The coils are formed by running

a continuous sheet of metal through a roll slitter.

Galvanizing is a process of coating iron or steel with zinc in order to provide greater

protection against corrosion for the iron or steel base.

The chemical composition of the coating is 55 % of Al, 43.5 % of Zn and 1.5 % of Si

and it is composed of a three-phase structure

Hot-dip Galvanizing:

The immersion of iron or steel in molten zinc, after the surface of the base metal has

been properly cleaned.

Fig 6.1.1 Galvanized sheet metal

10

6.1.2 THERMOCOL (POLYSTYRENE)

The white coloured foam which is also known as thermocol is generally used as a

good insulation material.

Our project is made up of sheet metal and it contains highly volatile chemical and

flammable substance which can be danger if allowed to pass heat through the body so to

insulate the whole body we used the insulation property of this thermocol and had a double

layered sheet metal body which not only restricts the transfer of heat but also keep the

refrigeration effect inside the refrigerator.

Thermocol being very light and very less weight by volume, large proportions can be

used for insulation purpose without any effect on the weight of the whole project and thus is

very suitable product for any kind of insulation.

Polystyrene (PS) is a synthetic aromatic polymer made from the monomer styrene.

Polystyrene can be solid or foamed.

In chemical terms, polystyrene is a long chain hydrocarbon wherein alternating

carbon centers are attached to phenyl groups (the name given to the aromatic ring benzene).

Polystyrene's chemical formula is (C8H8) n; it contains the elements carbon and hydrogen.

The material's properties are determined by short-range Vander attractions between

polymers chains. Since the molecules are long hydrocarbon chains that consist of thousands

of atoms, the total attractive force between the molecules is large. When heated (or deformed

at a rapid rate, due to a combination of viscoelastic and thermal insulation properties), the

chains are able to take on a higher degree of conformation and slide past each other.

Fig. 6.1.2 Polystyrene

11

6.1.3 DC BATTERY

The 12V DC lead acid battery is used are commonly used in cars and supplies enough

power for various appliances used in cars.

The battery we are using in our project takes 4 hour to get fully charged and being

used for the project.

This battery can be used to power fan and oxygen pump that is used for the

refrigeration system of our project.

In the discharged state both the positive and negative plates become lead (II)

sulfate (PbSO4), and the electrolyte lose much of its dissolved sulfuric acid and becomes

primarily water. The discharge process is driven by the conduction of electrons from the

negative plate back into the cell at the positive plate in the external circuit.

Negative plate reaction:

Pb(s) + HSO4

(aq) PbSO4(s) + H+(aq) + 2e

Positive plate reaction:

PbO2(s) + HSO4

(aq) + 3H+(aq) + 2e

PbSO4(s) + 2H2O(l)

The total reaction can be written as

Pb(s) + PbO2(s) + 2H2SO4(aq) 2PbSO4(s) + 2H2O(l)

Fig. 6.1.3 DC battery

12

6.1.4 DC FAN

The fan usually used in cars or other vehicles that runs on 12V DC current having

enough rotational speed and have good air blowing capacity.

The fan is mounted at the bottom of the fridge and the partition above the fan is made

to have to circular radius holes to supply air flow throughout the refrigerator.

Fig. 6.1.4 (a) DC fan

The partition containing the fan is closed later on to prevent the air from flowing in

multi direction and the holes on the sheet helps in the unidirectional flow of air to the top.

Fig. 6.1.4 (b) Fan below the holes

13

6.1.5 DC OXYGEN PUMP

An Air pump is used to aerate the water. It plugs in to a regular electrical outlet and is

usually attached to an air stone, tubing, etc. It is designed to pump air bubbles up through the

tank.

Here we are using the oxygen pump to blow air inside the acetone using a pipe to

create bubbles of acetone in the closed vessel.

Acetone being a volatile liquid has a property that when it is blown or heated it

produces cooling effect. Using the same property we are pumping air into acetone to produce

cooling effect and condense the vaporized acetone.

Fig. 6.1.5 DC oxygen pump

The pump used here is a single outlet pump that is mounted outside the refrigerator. It

intakes the air from the surrounding and supplies it inside the closed vessel to generate

bubbles of acetone.

The reaction inside the vessel takes as follows when oxygen is passed to the acetone:

CH3COCH3 + 4O2 = 3CO2 + 3H2O

Carbon dioxide (CO2) is used as a key cryogenic agent in cooling, chilling and

freezing applications protecting the taste and texture of your food products by maintaining

proper temperature control.

14

6.1.6 ALUMINIUM VESSEL

Aluminium is a chemical element in the boron group with symbol Al and atomic

number 13. It is a silvery white, soft, nonmagnetic, ductile metal. Aluminium is the third

most abundant element (after oxygen and silicon), and the most abundant metal in

the Earth's crust. It makes up about 8% by weight of the Earth's solid surface. Aluminium

metal is so chemically reactive that native specimens are rare and limited to

extreme reducing environments. Instead, it is found combined in over 270

different minerals. The chief ore of aluminium is bauxite.

Fig. 6.1.6 (a) Aluminium vessel

The aluminium vessel is used to contain acetone liquid and is placed above the fan.

When oxygen is pumped in acetone it generates CO2 making the vessel cold which absorbs

heat from the refrigerator.

Also Aluminium is an excellent conductor of heat and electricity. An aluminium

conductor weighs approximately half as much as a copper conductor having the same

conductivity. Aluminium is extremely durable in neutral and slightly acid environments.

Fig.6.1.6 (b) Aluminium vessel over the fan

15

6.1.7 ACETONE

Acetone (named propan-2-one)is the organic compound with the formula (CH3)2CO.

It is a colorless, volatile, flammable liquid, and is the simplest ketone.

The same volatile property has been utilized to obtain cooling effect for our

refrigeration system. We generally see when we put some acetone in our hand we feel cool in

our hand, the reason behind this cooling is that Acetone absorbs the heat for its vaporization

from our hand and makes us feel cool whereas acetone escapes by vaporizing.

Acetone is produced directly or indirectly from propylene. Approximately 83% of

acetone is produced via the cumene process; as a result, acetone production is tied to phenol

production. In the cumene process, benzene is alkylated with propylene to produce cumene,

which is oxidized by air to produce phenol and acetone:

Molecular formula C3H6O

Molar mass 58.08 g mol1

Appearance Colorless liquid

Density 0.79 g/cm3

Melting point 94.9 C, 178 K, -139 F

Boiling point 56.53 C, 330 K, 134 F

Fig. 6.1.7 Acetone

16

6.1.8 M-SEAL OR SEALANT

Sealant is a substance used to block the passage of gases or liquids through the

surface or joints or openings in materials, a type of mechanical seal. In building

construction, sealant is sometimes synonymous with caulking and also serve the purpose of

blocking dust, sound and heat transmission. Sealants may be weak or strong, flexible or rigid,

permanent or temporary. Sealants are not adhesives but some have adhesive qualities and are

called adhesive-sealants or structural sealants.

Sealants, despite not having great strength, convey a number of properties. They seal

top structures to the substrate, and are particularly effective in waterproofing processes by

keeping moisture out (or in) the components in which they are used. They can provide

thermal and acoustical insulation, and may serve as fire barriers. They may have electrical

properties, as well. Sealants can also be used for simple smoothing or filling. They are often

called upon to perform several of these functions at once.

Fig. 6.1.8 Sealant

Seeing the property of this sealant we used it as an alternative of silica gel. Silica gel

is also a material that is used to make air tight chambers or fill gap between parts

permanently. But as we discussed earlier that cost is our prime consideration so we decided to

adapt the M-Seal in place of silica gel and had the same result.

Here we are using M-seal to fill the gap between different parts or the gap between

the sheet metal bodies.

It is also used to seal the chamber to eliminate the leakage of acetone vapour and save

the acetone from being getting vaporized and loss to the environment.

17

6.1.9 SOLAR PANEL

Solar panels use light energy (photons) from the sun to generate electricity through

the photovoltaic effect. The majority of modules use wafer-based crystalline silicon cells

or thin-film cells based on cadmium telluride or silicon. The structural (load carrying)

member of a module can either be the top layer or the back layer. Cells must also be

protected from mechanical damage and moisture. Most solar modules are rigid, but semi-

flexible ones are available, based on thin-film cells.

Fig.6.1.9 Solar panel

Choosing the solar panel was a tough task because for this we have to consider many

things like rate of sunlight where we are making the refrigerator, capacity of the battery and

how fast we need it to get charged. Choosing the right power and voltage of the solar panel

can be done by using many solar panel calculators that are available online.

Here we are using a solar panel of 15 watt power to charge a 12V dc battery. The

solar panel is having a power volt of 18V so that when we use it to charge a 12 V battery the

18V get maintained at 13-15 V and thus we have a constant DC power supply.

Depending on construction, photovoltaic modules can produce electricity from a

range of frequencies of light, but usually cannot cover the entire solar range

(specifically, ultraviolet, infrared and low or diffused light). Hence much of the

incident sunlight energy is wasted by solar modules, and they can give far higher efficiencies

if illuminated with monochromatic light.

18

CHAPTER 7

7.1 WORK PLAN WITH TIMELINE

S.N ACTIVITY START

DATE

END

DATE

1. Selection of design parameter of the project 1st

March 11th

March

2. Selection of material for making the refrigerator 15th

March 16th

March

3. Selection of material for insulation of the whole body 16th

March 16th

March

4. Calculation of dimensions of the box used as

refrigerator

17th

March 20th

March

5. Preparation of the sheet metal box for refrigerator 22nd

March 2nd

April

6. Selection of DC fan as per required for refrigeration

system

3rd

April 5th

April

7. Selection of the aluminium vessel for storing the

chemical

3rd

April 6th

April

8. Selection of the volatile chemical required for cooling

mechanism

8th

April 10th

April

9. Calculation and selection of the oxygen pump required

to pump air inside the refrigerator

10th

April 13th

April

10. Selection of battery according to power required to run

the fan and air pump

13th

April 13th

April

11. Selection of Solar panel required to charge up the

battery

14th

April 14th

April

12. Sealing the box with sealant to make it leak proof 15th

April 15th

April

13. Assembly of all components of project in a circuit 16th

April 16th

April

14. Observation of the result after pouring acetone in the

vessel and calculation of the time required for

temperature drop

16th

April 16th

April

19

CHAPTER 8

8.1 EXPECTED OUTCOMES OF THE STUDY

The outcome of the project will be a working prototype of an acetone based refrigeration system powered by solar energy designed for rural application.

The construction of the assembly is relatively simple and we are sure that it

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.

However the construction is easy but the efficiency of temperature drop is

better than ice refrigeration that is used in commercial shops.

Our project would be able to stand among other refrigeration techniques due

to its less power consumption.

People get aware about the harmful effect of refrigerants used in other

refrigeration systems and prioritize the use of acetone as prime refrigerant which has no

harmful effect on the environment.

The innovative idea that we generated for using acetone based refrigeration

could be used further in commercial shops.

20

CHAPTER 9

9.1 PROCESS CARRIED OUT DURING THE CONSTRUCTION:

9.1.1 Box construction

For the refrigeration system first thing we need is a refrigerator box. Since GI sheet metal

is easily available in the market place and light weight when compared to other metals sheet.

The processes that are carried out while preparing the refrigerator box are as follows:

a) Shearing process

The process which use shearing force to cut, fracture or separate the material. Here we

use this process to cut the sheet as per dimensions to make the refrigerator box.

In this process enough shearing force is applied, the shear stress in the material will

exceed the ultimate shear strength and the material will fail and separate at the cut location.

This shearing force is applied by two tools, one above and one below the sheet.

Whether these tools are a punch and die or upper and lower blades, the tool above the sheet

delivers a quick downward blow to the sheet metal that rests over the lower tool. A small

clearance is present between the edges of the upper and lower tools, which facilitates the

fracture of the material. The size of this clearance is typically 2-10% of the material thickness

and depends upon several factors, such as the specific shearing process, material, and sheet

thickness.

Fig 9.1.1 (a) Shearing process

21

We also use the direct cutting method

b) Cutting Tools

Snips, also known as shears, are hand tools used to cut sheet metal and other tough webs.

These snipers are the most common cutting tools are available in the sheet metal lab or any

sheet metal working shop. They are categorized as follows:

Straight snip: - They have straight jaws and used for straight line cutting.

Curved snip: - They have curved blades for making circular cuts.

Fig 9.1.1 (b) Snipers

Forming process

Process which causes metal to undergo desired shape and the metal changes its shape

without failure like excessive thinning, or cracking. This includes bending and stretching.

During forming processes no material is removed, i.e. they are deformed and displaced.

Bending process is use to bend the corner of sheet. Here we use two method of bending.

c) V-Bending

In this the sheet metal is bending in v-shaped punch and dies. Included angle range from

very obtuse to very acute can be made with this dies. Here we bend the sheet to properly

shape the refrigeration box.

22

Fig 9.1.1 (c) V-Bending

d) Edge Bending

It is used to bend the edge to avoid the sharp edge of sheet to have better hold. It

involves the cantilever loading of sheet metal. A pressure pad is used to apply a force to hold

the base of part against the die, while the punch forces the part to bend over the edge of die.

Edge bending is limited to bend to 900 or less. For angles greater than 90

0 wiping die is used.

Fig 9.1.1 (d) Edge bending

The corners of the refrigerator box are made by bending a long sheet inspite of cutting

small sheets and joining them, as it takes more time to join every small sheet and it also

reduces the strength of the box.

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e) Final assembled project

By use of shearing, cutting and bending processes we make the refrigeration box.

Fig 9.1.1 (e) Refrigerator box

f) Internal chamber

By use of shearing, cutting and bending processes we made the refrigeration box.

Now to make the internal chamber we use different process as detailed below:

For making the upper chamber we cut the sheet as per dimensions and fit this sheet

with the use of screw. This chamber should be leak proof.

Note: The cutting should be as per dimensions and accurate.

Now to make the lower chamber the sheet is cut same as upper and fitted this with the

help of screw.

The middle chamber gets automatically made by the lower and upper chamber sheet.

24

Fig 9.1.1 (f) internal chamber of the refrigerator box

Aluminium vessel fitting:-

To fit the aluminium vessel in upper chamber sheet we use the slotting process.

g) Slotting process

This term is used for punching operation that cut out an elongated or spherical hole.

The diameter of the vessel is measured and a hole is slotted using the same diameter

so that the vessel gets fit in properly.

Fig 9.1.1 (g) Slotted hole to fit the aluminium vessel

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Air directed hole:-

To circulate the air inside the refrigeration we use the DC fan, to direct this air we

punched the hole in the lower chamber plate with the help of punching process.

h) Punching process

It is the shearing process which uses the punch and dies to separate the piece from the

surrounding stock. In this the separate piece is scrap, called the slug. The remaining stock is

the desired part.

Fig 9.1.1 (h) Punched holes for air passage

i) Gate

Gate of refrigeration box is made by use the cutting, shearing, bending and punching process.

Fig 9.1.1 (i) Air tight gate for refrigerator

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j) Refrigerator assembly

The entire component is assembled with the help of holder, screw driver, hammer.

Fig 9.1.1 (j) Assembled refrigerator

27

9.2 WORKING OF THE REFRIGERATION SYSTEM

Process 1

The main part of the solar refrigeration system is the solar panel. So we start our

process with the absorption of radiation from sunlight by solar panel and generation of power

which is stored in the battery. It takes almost 4 hour to fully charge up our battery, as

discussed earlier the charging time of the battery totally depends on the power of solar panel

and capacity of the battery.

Let say our battery is fully charged now, or else we can directly run our DC

components using direct sunlight by help of solar panels.

Process 2

Now what we need for refrigeration system is that acetone absorbs the heat from the

objects placed in the refrigerator. For the flow of heat we just installed a DC fan at the bottom

of the refrigerator which is almost 1 foot below the vessel.

The reason behind installing the fan is that firstly it helps in the flow of heat from the

object to the vessel by blowing air in the box.

Secondly it develops a low pressure at the bottom chamber and as the acetone gets

vaporized it develops a high pressure at the top chamber, and we know that cooling effect

flows from high pressure area to low pressure area. Thus the cooling effect transfers from the

top chamber while going downwards while passing to the fan. In this way we have the

refrigeration effect in the whole refrigerator box.

Process 3

The most important thing for the refrigeration to take place is the volatile chemical

which produces the cooling effect.

Acetone which is placed at the top chamber absorbs the heat for its vaporization from

the object placed in the box. Being highly volatile it requires very less heat to get vaporized

thus developing a high pressure at the top and making the object cooler.

Process 4

Now as the acetone is in the closed chamber and continuously being vaporized and

developing high pressure at the top chamber. The pressure of the upper chamber needs to be

control and maintained at a pressure. For this purpose we install a oxygen pump which

continuously blows oxygen by the pipe immersed in the acetone.

The bubbles produced by the blowing of oxygen produce cooling effect inside the top

chamber which condenses the vaporized chemical back to its normal liquidity. When the

28

acetone gets condensed the pressure again drops thus maintaining almost constant pressure in

the chamber and transfers the refrigeration throughout the refrigerator.

This whole process is repeated and we obtain refrigeration process in the refrigerator

for a long time without wastage of any energy.

The most important to consider during the whole process taking place is that we

should not allow the acetone vapors to leak from the refrigerator box. Because if the vapors

are allowed to escape after some time whole vapors will get escaped and we have to again put

acetone for refrigeration process.

To reduce the wastage and obtain refrigeration system for longer time duration we

sealed every portion of the chamber using M-seal and obtained almost leak proof chamber

and saved the chemical from wasting up.

Now the whole process or concept can be further shown using a simple block diagram

that is represented as:

29

Fig. 9.2 (a) Block diagram of the refrigeration system

As we can see the refrigeration system obtained is very simple and takes place within

less no of process.

Further we will represent the refrigeration system with a help of a typical diagram of

the refrigerator box and the components installed inside the refrigerator.

Solar panel absorbs

sunlight and produces

energy which is stored in

the battery.

The fan blows air to the

object and transfers heat

to the aluminium vessel

placed at the top.

Acetone absorbs the

heat for its vaporization

and gets vaporized

developing a high

pressure.

Oxygen pump blows

oxygen inside acetone

producing bubbles which

condenses back the

acetone.

1 2

3 4

30

Fig. 9.2 (b) Typical diagram of the refrigeration system

Aluminium vessel

containing acetone

12V DC oxygen

pump to create

bubbles in the

acetone

12V DC fan

Heat from the object is

carried to the vessel

The heat for vaporizing is

absorbed from the object

placed in between the fan and

the vessel

Pipe blows

oxygen or air

which is

absorbed by

acetone

12V Battery

powered by

solar panel High

pressure

chamber

Low

pressure

chamber

31

CHAPTER 10

10.1 SPECIFICATIONS OF PARTS OF THE SYSTEM

10.1.1 SHEET METAL BOX

Length = 50.80 cm (20 inches)

Breadth = 40.64 cm (16 inches)

Height = 68.58 cm (27 inches)

Thickness = 2.54 cm (1 inch)

Upper chamber

Length = 45.72 cm (18 inches)

Breadth = 38.10 cm (15 inches)

Height = 15.24 cm (6 inches)

Lower chamber

Length = 45.72 cm (18 inches)

Breadth = 38.10 cm (15 inches)

Height = 16.5 cm (6.5 inches)

Fig 10.1 Dimensions of the refrigerator

32

Mid chamber

Length = 45.72 cm (18 inches)

Breadth = 38.10 cm (15 inches)

Height = 31.75 cm (12.5 inches)

Gate

Length = 47.24 cm (18.6 inches)

Height = 66.04 cm (26 inches)

Breadth = 2.54 cm (1 inch)

10.1.2 OXYGEN PUMP

VOLT: AC230/115V/12V

FREQ: 50/60Hz

POWER: 2.5W

PRESSURE: 0.012MPa

OUTPUT: 3.2L/min

WEIGHT: 0.20kg

SIZE: 75x50x120mm

10.1.3 ALUMINIUM VESSEL

Height = 12cm (4.72 inches)

Diameter = 21 cm (8.26 inches)

10.1.4 FAN

Blade size: 15.24 cm (6 inches)

Size: 20.32 cm (8 inches)

Working voltage: 12/24 V DC

10.1.5 BATTERY

Power: 12V, 7.6 AH

Charging time: 4 hour

33

10.1.6 SOLAR PANEL

Power: 15 watt

Voltage: 18 V

Length:

Breadth:

10.1.7 RERFRIGERANT

Quantity: 2.5 liters

Grade: ACS (American Chemical Society)

Type: Acetone

Molecular formula: CH3COCH3

Molar mass: 58.08 g mol-1

Density: 0.79 g/cm3

Appearance: Colorless liquid

Melting point: -94.90C, 178 K, -139

0F

Boiling point: 56.530C, 330K, 134

0F

Fig. 10.1.7 Acetone

34

CHAPTER 11

11.1 RESULTS & DISCUSSION

The charging time of battery is 4 hour during full sunlight.

The Battery used is 12V generating 7.6AH which is used to run the fan and the oxygen pump.

Initial temperature inside the refrigerator: 270C

Final temperature: 160C

Time taken: 1 hour 50 min

S.No. Initial temperature Final temperature Time taken

1. 270C 24

0C 45 min

2. 270C 21

0C 1 hour 15 min

3. 270C 19

0C 1 hour 45 min

4. 270C 16

0C 2 hour 10 min

The final cooling temperature changes if the box is not leak proof i.e. if the box

contains gap in between there will be loss in acetone vapors and the cooling mechanism

would not work efficiently.

Thus for proper cooling or refrigeration it is necessary for us to seal all the gaps in the

box and make it air tight.

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CHAPTER 12

12.1 CONCLUSION

This project solar powered refrigeration system is operated by low grade solar energy, we

does not require any AC supply or any other high 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 and other small shops where they

use ice for cooling purpose.

This project is totally different from other refrigeration systems of VARS or VCRS systems.

In this project we tried to innovate a new refrigeration system that would be cost effective

and easily installed in any place. VARS or VCRS uses high grade energy and AC supply that

cannot be utilized by small scale shops. But our project focuses on cost so that it can be used

in small scale shops also.

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

costs but also preserving our environment. This refrigeration system doesnt use any of the

CFCs so our ozone layer is safe. Every new project is now made considering its effect on the

environment and how it is having impact on the global warming. So we also considered the

effect and made a environment friendly project.

36

REFERENCES

1. www-old.me.gatech.edu/jonathan.colton/me4210/sheetmetalproc.pdf

2. www3.nd.edu/~manufact/MPEM_pdf_files/Ch07.pdf

3. http://pubchem.ncbi.nlm.nih.gov/compound/acetone

4. https://www.youtube.com/watch?v=-_AqxTkrVXQ

5. http://thelibraryofmanufacturing.com/sheetmetal_bending.html

6. http://www.newworldencyclopedia.org/entry/Acetone

7. http://www.nrgmanagement.ca/refrigeration-process-cooling

8. nptel.ac.in/courses/112105129/pdf/RAC%20%20Lecture%201.pdf

9. www.gaa.com.au/index.php?page=mechanical-properties-of-galvanized.