A REPORT ON ENERGY EFFICIENT REFRIGERATION

MECHANICAL ENGINEERING

A

Project Report on

ENERGY EFFICIENT REFRIGERATION

Submitted to

„MAHARASHTRA STATE BOARD OF TECHNICAL EDUCATION‟

In partial fulfilment for the award of

Diploma in Mechanical Engineering

Submitted by

MR.KADUKAR ASHUTOSH G.

MR. KAKADE MAYUR J.

MR. KOLI SANDESH N.

MR. KUMBHAR VINAY S.

Under the guidance of

PROF. D. M. PATIL

DEPT. OF MECHANICAL ENGG.

NEW POLYTECHNIC, KOLHAPUR

2013-14


SHRI PRINCE SHIVAJI MARATHA BOARDING HOUSE‟S

NEW POLYTECHNIC, KOLHAPUR

CERTIFICATE

This is to certify that

1) MR. KADUKAR ASHUTOSH G. 2) MR. KAKADE MAYUR J.

3) MR. KOLI SANDESH N. 4) MR. KUMBHAR VINAY S.

of final year of diploma in Mechanical Engineering

have satisfactorily completed their project work entitled

“ENERGY EFFICIENT REFRIGERATION”

Under my supervision and guidance

Towards the partial fulfilment of award of

Diploma in Mechanical Engineering as laid by the

MAHARASHTRA STATE BOARD OF TECHNICAL EDUCATION,

MUMBAI

During academic year 2013-14.

Date:

Guide External Examiner HOD Principle


ACKNOWLEDGEMENT

We would like to place on record our deep sense of gratitude to Prof. D. M. Patil Sir for

his excellent guidance, help and constant encouragement during the completion of this project.

Our sincere thanks to Mr. Saiprasad Bondre, for his timely guidance and help.

We are thankful Prof. G. N. Munishwar (Head of Mechanical Dept.) and all staff

members for giving us the proper and constant guidance during this project. Without their

guidance it was really impossible task for us to complete this project.

Finally, we wish to thank all of our friends and those who directly and indirectly helped

us a lot during this course of project work.

Thank you,

Students‟ Names

Mr. Kadukar Ashutosh G.

Mr. Kakade Mayur J.

Mr. Koli Sandesh N.

Mr. Kumbhar Vinay S.


INDEX

CHAPTER NAME OF CONTENT PAGE NO.

1 Introduction 1

2 Field survey

3

Design

3.1. Conventional design

3.1.1. Vapour Compression Cycle

3.1.2. Vapour Compression Refrigeration System

3.2. Modified Design

3.2.1.Sub-cooling

3.2.2. Methods and Effects of Sub-cooling

3.2.3. Design Details

3.3. Details of parts of system

3.3.1. Compressor

3.3.2. Condenser

3.3.3. Capillary tube

3.3.4. Evaporator

3.3.5. Helping Condenser

4

Manufacturing Activities

4.1. Fabrication

4.1.1. Water Tank

4.1.2. Insulation

4.1.3. Box Mounting

4.1.4. Temperature Indicator

4.1.5. Water Cooled Condenser


4.1.6. Pressure Gauges

4.2. Machines/Tools Used

4.2.1. Hand Shear

4.2.2. Portable Drilling Machine

4.2.3. Fly Press

4.2.4. Riveter

4.2.5. Tube Cutter

4.2.6. Spring Pipe Bender

4.2.7. Flare

4.2.8. Gas Torch

4.2.9. Soldering Gun

4.2.10. Vacuum Pump

5 Testing

6 Results and Analysis

7 Conclusion and Scope For Future



CHAPTER NO.1


1. INTRODUCTION:

The fossil fuels and the petroleum fuels are depleting very fast and the human race has to

hunt for newer resources for energy. Similarly energy has to be saved and used very

economically because saving is earning. As such, we engineers working in several branches as

well as the end users of the machines/gadgets who are playing role of energy consumers should

think of the gadgets which are energy efficient.

Our project is endeavouring to save energy in our house by developing a gadget which utilizes

the heat coming out from the condenser. As such besides working to cool the milk, fruits,

vegetables, the refrigerator will also work as a heating device for some useful work.

The electrical energy consumption for a typical 200 lit. refrigerator is …. Kwh and the

approximate expenditure of running is …. The total amount of heat coming out of condenser is

… Kcal and this can be used for heating of 38 liters of water.

The various design parameters considered for developing this gadget are:

-Ease of manufacturing

-Low Cost

-Ease of adaptability/Installation

-High efficiency

-Compactness

The results obtained are fantastic and we hope that in the coming few years, this product will be

developed better than ours and be used on large scale.


CHAPTER NO.2


2. FIELD SURVEY:

Our field survey started with location where we were about to execute the entire project

regarding activities. We visited such locations and found four workshops for our project. The

two of which were located in Belbag near Gokhale College named „Viky Refrigeration‟ and

„Som Refrigeration‟ and one in Shivaji Udyamnagar named „Car Refrigeration‟ but due to

convenience of travelling and transportation, we finalized „Sai-Vabhav Refrigeration‟ located in

Uchgaon.

Next major part of our project was to buy a second-hand refrigerator. We finalized the

specification of the refrigerator as 190 liters with R134a refrigerant. We visited different

electronics shops and refrigeration industries in different locations around city. We selected a

good working refrigerator of specification of 200 liters and refrigerant R134a; near „Tatakadil

Talim Mandal, Rankala‟ from Mr. Juned Bagwan.

For fabrication of sheet metal boxes we visited two places. A shop in Shahupuri near the

Bagal Chowk and another shop in Belbag near Gokhale College. We fabricated sheet metal

boxes from the shop in Belbag.

For pressure gauges we visited „Kadam Refrigeration‟ in Shivaji Udyamnagar. Also for

temperature indicator and thermocouples we visited „Bombay Furnace‟ in Shivaji Udyamnagar.

Also for the rest of the materials like electrical wires, cables and piping materials, we visited

local shops in Uchgaon in the vicinity of our workshop.


CHAPTER NO.3


3. DESIGN:

3.1. CONVENTIONAL DESIGN:

The conventional design of any refrigeration system is based on the „Vapour

Compression Cycle‟ (VCC) and the system working on Vapour Compression Cycle is called

as „Vapour Compression Refrigeration System‟.

3.1.1. VAPOUR COMPRESSION CYCLE:

The Vapour Compression Cycle is as represented in the p-h diagram below. The diagram

represents Pressure (p) on X-axis and Enthalpy (h) on Y-axis.

P (Bar)

h (kJ/kg)

Pe

Pc

h3 = h4 h2 h1

Qa

Qr

W


i. Compression Process (1-2):

Vapour at evaporator pressure (Pc) enters into the compressor at state point 1. It is

compressed isentropically (reversible adiabatically) upto the discharge condenser pressure (Pc)

and vapour is assumed to become dry-saturated.

ii. Condensation Process (2-3):

Dry-saturated vapour at state point 2 enters the condenser where it rejects heat Qr at constant

pressure (Pc) to surrounding. It is assumed that the vapour is completely condensed and it

becomes saturated liquid.

iii. Expansion Process (3-4):

Saturated liquid at state point 3 and condenser pressure (Pc) is now passed through an

expansion device having restricted opening and it is throttled down to the evaporator pressure

(Pe). This process of throttling is constant enthalpy or isenthalpic process.

iv. Vaporization Process (4-1):

Slightly evaporated refrigerant enters into evaporator at state point 4, where the refrigerant

absorbs the heat (Qa) from space to be cooled. This effect of heat absorption is called as

„Refrigerating Effect‟. Now vapour refrigerant leaves the evaporator in vapour state as entry to

compressor at state point 1. Hence the cycle is completed.


3.1.2. VAPOUR COMRESSION REFRIGERATION SYSTEM:

The vapour compression refrigeration system by far is the most popular and widely used

system in refrigeration and air conditioning both for industrial and domestic applications.

In this system the working substance is a refrigerant like NH3, R-12, R-22, R-134a, etc.

A refrigerant readily evaporates and condenses depending upon the pressure and

temperatures during the cycle therefore; refrigerant undergoes a change of phase alternatively

between liquid and vapour phases without leaving the system.

Any vapour compression refrigeration system consists of four basic parts:

1) Compressor 2) Condenser 3) Expansion Device 4) Evaporator.

WORKING:

When the compressor is started it draws the low pressure vapour from the evaporator at state

point 1and compresses it isentropically to a sufficiently high pressure upto state point 2. Since

the compression work is done on the vapour, its temperature also increases.

Hot vapour from compressor under pressure is discharged into the condenser where it is

cooled at constant pressure by rejecting heat to condenser cooling medium; usually air. This

converts the hot vapour into liquid at state point 3. This liquid at high pressure is passed into

expansion device.

This expansion device, while restricting the flow, also reduces the pressure of the liquid

with the result liquid changes into vapour at low dryness fraction represented by state point 4.

During this process the temperature of refrigerant reduces corresponding to its pressure.

Finally, the low pressure, low temperature refrigerant passes through the evaporator coil

where it absorbs its latent heat from the space to be cooled or from the brine solution at constant

pressure and converts into vapour at state point 1. It is again applied to the compressor. Thus

cycle is completed.


3.2. MODIFIED DESIGN:

We modified the conventional design by implementing a water cooled condenser and

using the conventional air cooled condenser as a helping condenser. With this modified design,

we have been able to obtain the effect of „Sub-Cooling‟ at the cost of heated water which is

usable for daily needs.

Before going into the physical construction of the refrigerator, let us understand the concept of

„Sub-Cooling‟ followed by the methods and effects of sub-cooling.

3.2.1. SUB-COOLING:

Sub-Cooling can be simply defined as, “Cooling of the refrigerant below its saturation

temperature at constant pressure.”

Sometimes it happens that the liquid refrigerant flowing through the condenser gets

cooled below its saturation temperature before entering into the expansion device. Also it may be

obtained by installing a „Sub-Cooler‟ between the condenser and the expansion valve.

The diagram below represents the effect of sub-cooling the refrigerant. Ideal cycle is

represented by (1-2-3-4) and the cycle with sub-cooling is represented by (1-2-3’-4’)

P (Bar)

h (kJ/kg)

Pe

Pc

h3 = h4 h2 h1

Qa

Qr

W

h3’ = h4’

3’

4’


3.2.2. METHODS AND EFFECTS OF SUBCOOLING:

Below discussed are the two cases by which sub-cooling can be achieved artificially, followed

by their effects if employed in a system.

In case the sub-cooling of liquid refrigerant is achieved by refrigerant from condenser at

state point 3 through a heat exchanger in which cold vapour from evaporator flows in opposite

direction. The effects of sub-cooling are stated below:

i. It superheats the vapour entering into the compressor. Superheating results in increased

volume of vapour to be compressed; consequently increasing compressor work.

ii. Though it increases the refrigerating effect, but it may not increase the COP of the system

due to increased compressor work.

iii. However it overcomes the disadvantage of wet compression.

If we consider our project, the sub-cooling of the refrigerant is achieved by water-cooling the

condenser coil. The condenser coil connected to discharge of compressor is directly circulated in

a water tank. Thus the heat rejected by refrigerant from condenser (between state points 2-3) is

absorbed by the water in the tank and refrigerant gets sub-cooled. The effects of sub-cooling are

as stated below:

i. Sub-cooling increases the refrigerating effect (Qa) by an amount (h4-h4’)kJ/kg, therefore,

reduces the mass of refrigerant to be circulated.

ii. Though the compressor work remains the same per kg of refrigerant, but, it reduces the

compressor power per tonne of refrigeration due to reduced mass flow rate of refrigerant.

iii. Also it reduces piston displacement of compressor.

Increases the COP of the system.


3.2.3. DESIGN DETAILS:

Figure below represents the schematic arrangement of the actual modification of refrigerator.

The basic parts used in our vapour compression refrigeration system include:

1) Compressor 2) Water Cooled Condenser 3) Helping Condenser 4) Capillary 5) Evaporator

i. Compressor discharge is connected to water cooled condenser.

ii. The outlet of water cooled condenser is connected to the air cooled condenser which acts

as a helping condenser.

iii. Outlet of the helping condenser is connected to the expansion device. In this case a

capillary tube is used as an expansion device.

iv. Outlet of capillary tube is connected to evaporator.

v. Outlet of evaporator is connected to compressor suction.


3.3. DETAIILS OF PARTS OF SYSTEM:

3.3.1. COMPRESSOR:

The hermetically sealed reciprocating compressor is widely

used for the refrigeration and air conditioning applications. One can

find it in all the household refrigerators, deep freezers, window air

conditioners, split air conditioners, most of the packaged air

conditioners.

In hermetically sealed compressor, the compressor and the motor are enclosed in the

welded steel casing and the two are connected by a common shaft. This makes the whole

compressor and the motor a single compact and portable unit that can be handled easily. The

hermetically sealed compressor is very different from the traditional open type of compressors in

which the compressor and the motor are different entities and the compressor is connected to the

motor by coupling or belt.

In hermetically sealed compressor, in one side of the enclosed casing the various parts of

the compressor like cylinder, piston, connecting rod and the crankshaft are located. On the other

side of the casing is the electric winding inside which the shaft of the motor rotates. In

hermetically sealed compressors the crankshaft of the reciprocating compressor and the rotating

shaft of the motor are common. The rotating shaft of the motor extends beyond the motor and

forms the crankshaft of the hermetically sealed reciprocating compressor.

All these parts of the hermetically sealed compressor are assembled and enclosed in a strong and

rigid casing made up of welded steel shell. The steel shell comprises of two half rounded steel

bodies that are welded together to form the casing for the hermetically sealed compressor. In

some cases the two halves of the shell can be bolted together instead of welding, which permits

easy opening of the casing in case of compressor burnout.


3.3.2. CONDENSER:

A refrigerator condenser is one of the main operating components that make up the

cooling system on a standard refrigerator. It consists of a series of copper tubes that overlap in a

grid or coiling pattern. On most models, the condenser is located at the back of the unit, though

some may be installed on the bottom or along one side of the unit. While its size can vary, it

often covers at least half of the area of the refrigerator wall, and some even cover the entire wall

of the unit.

Combined with the evaporator unit within the fridge, the condenser removes heat from

inside the refrigerator and transfers it to the outside of the unit. A series of metallic tubes or pipes

connect the two devices, and liquid refrigerant passes through these tubes to travel from one to

the other. As the refrigerant passes through the evaporator, it collects heat energy from within the

refrigerator or freezer, leaving the inside of the unit cold enough for food storage. The extra heat

energy warms the refrigerant, causing it to transform into a gaseous material. This gaseou

refrigerant then travels down to the condenser.

As the refrigerant passes through the condenser heat transfer takes place by which

refrigerant inside gets cooled and the excess heat energy is exhausted into the room. Once the

heat leaves the refrigerant, it transforms back into a liquid and then travels back into the

evaporator to repeat this cooling cycle.


3.3.3. CAPILLARY TUBE:

Capillary tube is one of the most commonly used throttling

devices in the refrigeration and the air conditioning systems. The

capillary tube is a copper tube of very small internal diameter. It is

of very long length and it is coiled to several turns so that it would

occupy less space. The internal diameter of the capillary tube used

for the refrigeration and air conditioning applications varies from

0.5 to 2.28 mm (0.020 to 0.09 inches). Capillary tube used as the

throttling device in the domestic refrigerators, deep freezers, water

coolers and air conditioners.

When the refrigerant leaves the condenser and enters the capillary tube its pressure drops

down suddenly due to very small diameter of the capillary. In capillary the fall in pressure of the

refrigerant takes place not due to the orifice but due to the small opening of the capillary.

The decrease in pressure of the refrigerant through the capillary depends on the diameter

of the capillary and the length of the capillary. Smaller is the diameter and more is the length of

the capillary more is the drop in pressure of the refrigerant as it passes through it.

In the normal working conditions of the refrigeration plant there is drop in pressure of the

refrigerant across the capillary but when the plant stops the refrigerant pressure across the two

sides of the capillary equalize. Due to this reason when the compressor restarts there won‟t be

much load on it. Also, due to this reason one cannot over-charge the refrigeration system with

the refrigerant and receiver is not required.

The capillary tube is non-adjustable device that means one cannot control the flow of the

refrigerant through it as one can do in the automatic throttling valve. Due to this the flow of the

refrigerant through the capillary changes as the surrounding conditions changes. However, if it is

selected properly, it can work reasonably well over a wide range of conditions.


3.3.4. EVAPORATOR:

It is in the evaporators where the actual cooling

effect takes place in the refrigeration and the air

conditioning systems. 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.

In the domestic refrigerators the evaporators are commonly known as the freezers since

the ice is made in these compartments. In case of the window and split air conditioners and other

air conditioning systems where the evaporator is directly used for cooling the room air, it is

called as the cooling coil. In case of large refrigeration plants and central air conditioning plant

the evaporator is also known as the chiller since these systems are first used to chill the water,

which then produces the cooling effect.

In the evaporator the refrigerant enters at very low pressure and temperature after passing

through the expansion device. This refrigerant absorbs the heat from the substance that is to be

cooled so the refrigerant gets heated while the substance gets cooled. Even after cooling the

substance the temperature of the refrigerant leaving the evaporator is less the than the substance.

The refrigerant leaves the evaporator in vapour state, mostly superheated and is absorbed by the

compressor.


3.3.5. HELPING CONDENSER:

Helping condenser is a normal air cooled condenser

used to transfer the heat rejection load when the water

cooled (primary) condenser is unable to reject the heat or is

malfunctioning. The inlet of helping condenser is

connected to outlet of water cooled and outlet is connected

to the capillary tube inlet.

As in case of our project, the water cooled

condenser is a copper coil circulated in water tank. The

water cooled condenser is directly connected to the

compressor discharge. The water cooled condenser will

efficiently reject the heat until temperature of water comes

in equilibrium with temperature of refrigerant flowing through the water cooled condenser. Thus,

when this state is reached, hot water in the tank needs to be replaced with relatively cold water;

otherwise the refrigerant will not condense and result in malfunctioning of the entire system.

So from safety consideration as well as to ensure smooth working of refrigeration system,

we used the air cooled condenser as a helping condenser. Such that when water cooled condenser

stops rejecting heat, the heat rejection load is naturally transferred to the helping condenser

which rejects heat to atmospheric air; ensuring that the refrigerant condenses normally and the

system works smoothly.


CHAPTER NO.4


4. MANUFACTURING ACTIVITIES:

4.1. FABRICATION:

4.1.1. WATER TANK:

Our fabrication activities started with fabrication of water tank. For this we had to

fabricate two boxes of sheets of galvanized iron. Such that the internal box would store the water

and the external box would carry the puff insulation.

Initially we made marking on the sheets of galvanized iron. Then we cut the sheets as per

the desired dimensions with the help of a hand shear. Thereafter the different cut sections of

sheet were bent by using hand press such that appropriate shape of box is obtained. After the two

boxes were ready, a lid to cover the internal box was fabricated which would fit into the rim of

internal box. So as to make the water tank leak-proof the edges and corners of boxes were

soldered with soldering gun.

4.1.2. INSULATION:

For facilitating of pouring of insulation, we provided holes on the top side of the box.

Now for the preparation of puff insulation, we combined two chemicals named ...... in a jug.

These two chemicals react with each other to form a bubbly froth of insulation. This insulation is

poured in through the holes ensuring that it is distributed evenly through the entire space

between two boxes. Same goes for the insulation of lid. Two holes were drilled diagonally and

insulation was poured. After this, we waited until puff insulation got cured completely which

generally takes upto 5 minutes.


4.1.3. BOX MOUNTING:

For fixing the box rigidly on top of the refrigerator, we decided to provide three strips on

either sides and back side of the box. For this, we cut strips of stainless steel from scrap using

hand shear and riveted those strips on the refrigerator and on the box with the use of puff rivets.

Now for facilitating draining of water, we provided a hole using drilling machine at the

bottom of tank. We bent a copper pipe using spring pipe bender; also increased its diameter from

one end using flare. This pipe was inserted & soldered in the previously drilled hole. A tap is

provided which is connected to copper pipe outlet through a flexible pipe. Flexible pipe is fixed

using clamps.

4.1.4. TEMPERATURE INDICATOR:

For installation of temperature indicator, we fabricated a box from sheet of galvanized

iron. For this, we made marking on sheet as per dimensions and cut accordingly using hand

shear. Now sections of sheet were bent as desired using hand press. Now after the box was ready,

temperature indicator was mounted into the box and the box was riveted to the water tank using

puff rivets.


4.1.5. WATER COOLED CONDENSOR:

For assembly of water cooled condenser, we had to cut the conventional condenser coil

which would act as a helping condenser. So before cutting the condenser coils, we released the

refrigerant to atmosphere. Now the condenser coils were cut as required using a pipe cutter.

For coils of water cooled condenser, we bent a copper pipe using spring pipe bender

which would fit in the water tank. Now the copper pipe was welded (to compressor discharge

and inlet of helping condenser) using butane gas torch.

4.1.6. PRESSURE GAUGES:

For the installation of pressure gauges, we provided two holes one on the evaporator coils

at compressor suction and one on condenser coils at compressor discharge. We fit suction and

delivery pressure gauges in respective holes and welded to make the assembly leak-proof. Now

using a vacuum pump, the refrigerant was charged into the system. Also to ensure that the

system is leak proof, we carried out a leakage test.


4.2. TOOLS USED:

Below illustrated are the tools used during fabrication activities with their description.

4.2.1. HAND SHEAR:

Hand shear is similar to the scissors

which are commonly used. Hand shear is a

handy cutting tool used to cut through sheet

metal to obtain sections of sheet to the desired

dimensions. A hand shear consists of two arms

connected with oppositely constructed knife

edges. These arms with knife edges are pivoted

at an interval where cutting knife edges end. A

compression spring is used between arms to

facilitate easier cutting operation.

4.2.2. PORTABLE DRILLING MACHINE:

Portable drilling machine is a compact & handy

version of floor mounted drilling machine. This machine uses

an electric motor to rotate spindle. Spindle has a jawed chuck

in which a drill bit can be held rigidly. Rotary drill bit (twist

drill) is used as a cutting tool. With use of a drill bit a hole of

size of bit can be drilled in the surface. Thus we can obtain a

hole of desired size using respective drill bit.


4.2.3. FLY PRESS:

Fly press is a manually operated type

press which works on the principle of nut and

screw which convert rotary motion into linear

motion. The press uses flywheel or flyballs

for maintaining the inertia of the punch.

Punch can be attached with a horizontal plate

which can be used to bend sections sheet metal

into desired angle; forcing them against a die.

4.2.4. RIVETER:

Riveter is a device used to

fix rivets in previously drilled hole.

It consists of a head to hold rivet stem.

When the lever is operated, stem of

rivet is pulled and shank of rivet is

compressed. Compressive force

crushes and warps rivet shank which

results in fastening of two sheets

rigidly.

Rivet Shank

Rivet Stem

Rivet Head


4.2.5. TUBE CUTTER:

Tube cutter is a very small tool used to cut

the pipe to required length. It consists of an adjustable

frame and a movable arm. This facilitates easy

accommodation of tubes of different diameters.

Movable arm holds a circular disc with cutting edges

on its periphery which can rotate freely. There are two

rollers to opposite side of the disc which support the

pipe. Tube cutter is fit and tightened on pipe. After

which it is rotated continuously about the axis of tube

until the tube is cut.

4.2.6. SPRING PIPE BENDER:

Spring bender is a device used to bend metallic pipe manually. The spring used for pipe

bender is tension spring. Use of tension spring reduces efforts required to bend a particular

section of pipe. Pipe is inserted in the spring. Spring is moved over to the section which is to

be bent. Now with force of hand,

pipe is bent as per the requirement.


4.2.7. FLARE:

Flare is a tool which is used to enlarge the

diameter of pipe at the inlet or outlet of the pipe.

Flare is made up in two halves for facilitating easy

fitment of pipes in flare. Flare can accommodate

standard sizes of pipes in its pre-form holes. Once

the pipe is fit in flare, with the use of flare puller, a

conical center is forced against mouth of the pipe.

This results in compression of metal and

consequently the diameter of respective end gets

enlarged. There is a wide range of flares available

according to diameters and mouth sizes.

4.2.8. GAS TORCH:

Gas torch is used for gas welding

operation. Gas torch consists of a nozzle

from which gas comes out. The quantity

or discharge of gas can be controlled using

regulator fit on top of conducting pipe.

Gas is stored in a cylinder. Gas used may

be Butane, Isobutene or Oxy-acetylene.

Butane gas torches have claimed to develop

temperatures as high as 1430C.

Temperatures as high as this are enough to

fuse two materials in each other to obtain a

leak-proof welded joint.


4.2.9. SOLDERING GUN:

Soldering gun is an approximately pistol-

shaped tool for soldering metals using tin-based

solder to achieve a strong mechanical bond with good

electrical contact. It works on the principle of

electrical resistance to rapidly heat the tip of gun.

Soldering gun was used to solder edges and corners

of boxes of water tank for leak proofing. Soldering

process also reduces hassle of fastening with the use

of screws and rivets.

4.2.10. VACUUM PUMP:

Vacuum pump is used for charging of

refrigerant into the system. For this, pump is

attached on the charging line of the compressor.

After which, the pump is run to force all the air

and remaining refrigerant out of the system such

that, partial vacuum is created in the system. This

process takes about 20 minutes. Now for

charging the refrigerant, vacuum pump is

removed and a cylinder consisting compressed

refrigerant is attached to charging line of

compressor. Refrigerant is sucked into the system

which due to partial vacuum; thus the refrigerant

is charged into the system.


CHAPTER NO.5


5. TESTING:



CHAPTER NO.6


CHAPTER NO.7


7. SCOPE:

Our project is a small scale model which can be employed on any vapour compression

refrigeration system to improve its COP.

Such system can be employed in processing industries such as food processing industry or

dairy industry where large amounts of heat is dissipated to atmosphere as waste. The figure

below represents an example where heat recovery unit (HRU) is used in dairy industry.

As seen in the figure, a heat recovery unit is installed on the condensers of refrigeration

system. Now the heat is dissipated from the refrigerant flowing through the condenser coil into

the water. This assembly as a whole is called as „HRU or Heat Recovery Unit‟. Employing a

HRU on a vapour compression refrigeration system provides the effect of sub-cooling. Sub-

cooling increases the refrigerating effect (Qa) consequently increasing the COP of the system but

keeping the compressor work constant at the same time.

Now the heated water from HRU can be pumped into the water drum of boiler as pre-heated

water. Using pre-heated water as inlet of water drum of boiler reduces the heat required to

convert water into steam; resulting in reduced fuel consumption of boiler.


CHAPTER NO.


COSTING:

Sr. No. Material Qty Cost (Rs.)

1 Fridge 1 5850

2 Boxes and lid 2 1800

3 Puff Insulation and service charge - 2500

4 Sub-Zero 1 700

5 Temperature Indicator 1 2250

6 Pressure gauge 2 700

7 Thermocouple 1 72

8 Pipes and wires 200


ANALYSIS:

STEPWISE PROCEDURE:

1. Follow the precautions as specified by the manufacturer such as never operate the unit if

voltmeter on the panel reads less than 220 V or more than 240 V.

2. Keep the load in evaporator.


CALCULATIONS:

Observations:

Readings for COP calculations.

Sr. No. Description Symbol Reading

1 Initial temperature in evaporator T1 29C

2 Final temperature in evaporator T2 8C

3 Evaporator Pressure P1 5 Psi

4 Condenser Pressure P2 135 Psi

5 Initial Energy meter Reading E1 779.6 units

6 Final Energy meter Reading E2 780.0 units

7 Time of Test T 7200 sec

1) Calculations of Theoretical COP


2) Calculations of Actual COP:

Actual COP = Actual refrigerating effect / Actual Work

= Qact / Wact

Qact = mw x Cpw x (ti-tf) / time (sec)

= 3 x 4.2 x (29-8) / 7200

Qact = 0.03765 kJ/sec

Wact = Ef – Ei / time (Hr)

= 780.0 - 779.6 / 2

Wact = 0.2 KW

Actual COP = Qact / Wact

= 0.03765 / 0.2

COPact = 0.18

A REPORT ON ENERGY EFFICIENT REFRIGERATION

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