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Advanced Engineering and Applied Sciences: An International Journal
Universal Research Publications. All rights reserved
ISSN 2320–3927
Original Article
FABRICATION AND ANALYSIS OF REFRIGERATOR CUM CHILLED
WATER DISPENSER
P.Dasthagiri1, H.Ranganna2, G. Maruthi Prasad Yadav3
1. PG Student, Mechanical Engineering Dept, St Johns College of Engg & Technology, Yemmiganur-518360, Kurnool
(Dist), AP
2 & 3.Associate Professor, Mechanical Engineering Dept, St Johns College of Engg & Technology, Yemmiganur-518360,
Kurnool(Dist), AP, maruthiprasadyadav@gmail.com.
Received 04 March 2015; accepted 20 March 2015
Abstract
The invention of refrigerator has changed the lifestyle of people. The refrigerator is used to store food items, medicines,
beverages and such other materials. The useful life of foods and other items can be lengthened due to storing at low
temperatures. Now a day’s refrigerator is not a luxury it has become part of requirements in every middle and lower middle
class households. The household’s refrigerator is also used for cool water and ice cubes. The consumption cold water
requires frequent opening of the refrigerator doors, this decreases the performance of the refrigerator as well as the food
item stored undergo sharp rise in temperatures around.
Hence providing a separate water cooler/chilling provision with in the refrigerator and providing a convenient water
outlet without opening the doors will be very advantageous for the performance of the refrigerator.
The Refrigerator consists of compressor, condenser coils, expansion devices and evaporator coils. In this system a
hermitically sealed compressor having capacity of about 120 watts, an air cooled condenser, an evaporator coil are
generally used.
In The present work a domestic refrigerator is modified to serve both the purposes as refrigerator and water dispenser.
Suitable design and operation conditions were modified with a view to save space, initial cost and maintenance costs.
© 2015 Universal Research Publications. All rights reserved
out at temperature higher than the surroundings. It is also
clear that the foodstuff placed inside the refrigerator is
1. INTRODUCTION
Vapour-compression refrigeration is one of the many cooled by giving out their heat to the refrigerator which in
refrigeration cycles available for use. It has been and is the turn, so to say, absorbs heat q1, of course at lower
most widely used method for air-conditioning of large temperature than the surroundings. Every refrigerator is
public buildings, offices, private residences, hotels, supplied with energy wither in the form of heat or
hospitals, theaters, restaurants and automobiles. It is also electricity, that is, some work (w) is provided to it. The
used in domestic and commercial refrigerators, large-scale refrigerating device, thus is absorbing heat at lower
warehouses for chilled or frozen storage of foods and temperature and giving out at higher temperature; this is
meats, refrigerated trucks and railroad cars, and a host of usually not possible in our day to day life, since heat cannot
other commercial and industrial services. Oil refineries, flow from lower to higher temperature, but in case of a
petrochemical and chemical processing plants, and natural refrigerator this is achieved at the cost of energy supplied to
gas processing plants are among the many types of it. For the boundary total heat given out (q 2) is equal to the
industrial plants that often utilize large vapor-compression total energy input in the form of heat absorbed (q 1) and the
refrigeration systems.
work absorbed (w) Balancing them.
Refrigeration may be defined as lowering the temperature
For a refrigerator device, we are interested in how much
of an enclosed space by removing heat from that space and heat is extracted from food stuff and how little electrical
transferring it elsewhere. A device that performs this energy we spend, minimizing our power bill. The ratio of
function may also be called a heat pump.
heat absorbed to the work input in the form of electric
energy (w) is called coefficient of performance (COP). The
Energy analysis of Refrigeration
Consider a boundary enclosing a space in which a ratio should be as high as possible.
refrigerator is placed. It is clear that some heat q 2 is given
C.O.P = 𝑞1/𝑤 = q1/(q2-q1)
7
Advanced Engineering and Applied Sciences: An International Journal 2015; 5(1): 7-14
Theoretical COP is ratio of theoretical refrigerating
effect (N), found from pressure heat content chart or
temperature -entropy chart to the theoretical compressor
work (W) or isentropic compressor work, found from the
chart.
Actual COP is the ratio of actual cooling effect, to
the actual energy supplied to the compressor known from
watt-hour reading.
Relative COP is the ratio of actual to the theoretical
COP. It is a pure number without any unit.
2. DOMESTIC REFRIGERATOR
Most domestic refrigerators are of two types—either a
single door fresh food refrigerator or a two-door
refrigerator-freezer combination, with the freezer
compartment on the top portion of the cabinet, or a
vertically split cabinet (side-by-side), with the freezer
compartment on the left side of the cabinet. They are
completely self-contained units and are easy to install.
Most refrigerators use R-22 refrigerant, normally
maintaining temperatures of -17oC in the freezer
compartment and about 1.66oC to 7.22oC in the refrigerator
compartment. The technician must be able to perform
various duties in the maintenance and repair of domestic
refrigerators, water coolers, and ice machines. This section
provides information to aid you in handling some of the
more common types of troubles. But let us remind you that
the information given here is intended as a general guide
and should, therefore, be used with the manufacturer's
detailed instructions.
2.1Domestic Refrigerator Parts and their Working
The domestic refrigerator is one found in almost all the
homes for storing food, vegetables, fruits, beverages, and
much more. This article describes the important parts of the
domestic refrigerator and also their working. The parts of
domestic refrigerator can be categorized into two
categories: internal and external. Let see these in details
along with their images.
2.1.1 Internal Parts of the Domestic Refrigerator
The internal parts of the refrigerator are ones that carry out
actual working of the refrigerator. Some of the internal
parts are located at the back of the refrigerator, and some
inside the main compartment of the refrigerator. Some
internal parts of the domestic refrigerator are (please refer
the figure1):
1) Refrigerant: The refrigerant flows through all the
internal parts of the refrigerator. It is the refrigerant that
carries out the cooling effect in the evaporator. It absorbs
the heat from the substance to be cooled in the evaporator
(chiller or freezer) and throws it to the atmosphere via
condenser. The refrigerant keeps on recirculating through
all the internal parts of the refrigerator in cycle.
2) Compressor: The compressor is located at the back of
the refrigerator and in the bottom area. The compressor
sucks the refrigerant from the evaporator and discharges it
at high pressure and temperature. The compressor is driven
by the electric motor and it is the major power consuming
device of the refrigerator.
3) Condenser: The condenser is the thin coil of copper
tubing located at the back of the refrigerator. The
refrigerant from the compressor enters the condenser where
8
it is cooled by the atmospheric air thus losing heat absorbed
by it in the evaporator and the compressor. To increase the
heat transfer rate of the condenser, it is finned externally.
Fig 1 Internal parts of domestic refrigerator
4) Expansive valve or the capillary: The refrigerant leaving
the condenser enters the expansion device, which is the
capillary tube in case of the domestic refrigerators. The
capillary is the thin copper tubing made up of number of
turns of the copper coil. When the refrigerant is passed
through the capillary its pressure and temperature drops
down suddenly.
5) Evaporator or chiller or freezer: The refrigerant at very
low pressure and temperature enters the evaporator or the
freezer. The evaporator is the heat exchanger made up of
several turns of copper or aluminum tubing. In domestic
refrigerators the plate types of evaporator is used as shown
in the figure above. The refrigerant absorbs the heat from
the substance to be cooled in the evaporator, gets
evaporated and it then sucked by the compressor. This
cycle keeps on repeating.
6) Temperature control devise or thermostat: To control the
temperature inside the refrigerator there is thermostat,
whose sensor is connected to the evaporator. The
thermostat setting can be done by the round knob inside the
refrigerator compartment. When the set temperature is
reached inside the refrigerator the thermostat stops the
electric supply to the compressor and compressor stops and
when the temperature falls below certain level it restarts the
supply to the compressor.
7) Defrost system: The defrost system of the refrigerator
helps removing the excess ice from the surface of the
evaporator. The defrost system can be operated manually
by the thermostat button or there is automatic system
comprising of the electric heater and the timer.
Those were the some internal parts of the domestic
refrigerator; now let us see the external parts of the
refrigerator.
2.1.2 External Visible Parts of the Refrigerator
The external parts of the compressor are the parts that are
visible externally and used for the various purposes. The
figure 2 shows the common parts of the domestic
refrigerator and some them are described below:
1) Freezer compartment: The food items that are to be kept
at the freezing temperature are stored in the freezer
compartment. The temperature here is below zero degree
Celsius so the water and many other fluids freeze in this
compartment. If you want to make ice cream, ice, freeze
Advanced Engineering and Applied Sciences: An International Journal 2015; 5(1): 7-14
the food etc. they have to be kept in the freezer
compartment.
2) Thermostat control: The thermostat control comprises of
the round knob with the temperature scale that help setting
the required temperature inside the refrigerator. Proper
setting of the thermostat as per the requirements can help
saving lots of refrigerator electricity bills.
3) Refrigerator compartment: The refrigerator compartment
is the biggest part of the refrigerator. Here all the food
items that are to be maintained at temperature above zero
degrees Celsius but in cooled condition are kept. The
refrigerator compartment can be divided into number of
smaller shelves like meat keeper, and others as per the
requirement.
4) Crisper: The highest temperature in the refrigerator
compartment is maintained in the crisper. Here one can
keep the food items that can remain fresh even at the
medium temperature like fruits, vegetables, etc.
5) Refrigerator door compartment: There are number of
smaller subsections in the refrigerator main door
compartment. Some of these are egg compartment, butter,
dairy, etc.
6) Switch: This is the small button that operates the small
light inside the refrigerator. As soon the door of the
refrigerator opens, this switch supplies electricity to the
bulb and it starts, while when the door is closed the light
from the bulb stops. This helps in starting the internal bulb
only when required.
Because you milk is colder than the room, heat energy
moves from the room into the milk. This movement of heat
energy affects the objects involved, your supper or milk,
changing their temperatures. This concept of moving heat
has a direct bearing on our lives. In the winter, we move
heat from a fire, or a radiator, or an electric heater into our
house, changing its temperature. In summer, we want to do
the opposite, move heat from our house to somewhere else
(we don’t really care where), again changing the
temperature of our house.
Fig 3 Principle of refrigerator
2.3 Technical Data of a Typical Household Refrigerator
1. Compressor H.P.-1/8 to 1/6.
2. Capillary-0.82 mm in diameter.
3. Normal refrigerant charge-160 to 190 grams for 165
liters capacity but varies as per
capacity.
4. Power consumption - 3 to 4 kW-hr for 286 liters capacity
refrigerator per day and 2 to 3 kWh for 165 liters capacity
unit.
5. Maximum running time- 40 to 60% of day time for small
refrigerator and 60 to 80% for bigger refrigerator.
6. Lower evaporator temperature-(-17±2)0 C.
7. Temperature in chill tray-0o C or below.
Fig 2 External parts of refrigerator
8. Suction pressure -0.7 to 1.6 bars.
2.2 Basic Refrigeration Principle
9. Discharge pressure-12 to 15 bars.
If you were to place a hot cup of coffee on a table and leave
3. WATER COOLERS
it for a while, the heat in the coffee would be transferred to The purpose of water coolers is to make water available at
the materials in contact with the coffee, i.e. the cup, the a constant temperature irrespective of ambient temperature.
table and the surrounding air. As the heat is transferred, the They are meant to produce cold water at about 7 oC to 13oC
coffee in time cools. Using the same principle, refrigeration for quenching the thirst of the people working in hot
works by removing heat from a product and transferring environment. The warm or normal water can serve the
that heat to the outside air. The principle involves the physical requirement of our system for the proper
transfer of heat. We could discuss entropy and the laws functioning of the body organs but it does not quench the
of thermodynamics, but we’re not going to do that. That thirst especially in hot summers.
isn’t really necessary to understand this concept. It is one 3.1 Types of Water Coolers
that we are all familiar with, whether we have any interest The water coolers are two types i.e. the storage type and the
in science or not. If you take your supper off the stove but instantaneous type. In the storage type water coolers, the
don’t eat it right away, it gets cold. If you leave the evaporator coil is soldered on to the walls of the storage
milk out on the counter, it gets warm. Actually, your supper tank of the cooler, generally on outside surface of the walls.
and your milk would become the same temperature, the The tank may be of galvanized steel or stainless steel
temperature of the room. Because your supper is hotter than sheets. The water level in the tank is maintained by a float
the room, heat energy moves from it into the room. valve. In this type of water cooler, the machine will have to
Advanced Engineering and Applied Sciences: An International Journal 2015; 5(1): 7-14
9
run for long time to bring down the temperature of the mass
of water in the storage tank. Once the temperature touches
the set point of the thermostat, the machine cycle is
stopped. When the water is drawn from the cooler and an
equal amount of fresh water is allowed in the tank, the
temperature will rise up slowly and the machine starts
again. As such there is always a reservoir of cold water all
the time.
Fig.4 cooling coil of instantaneous type cooler
In instantaneous type water coolers, the evaporator
consists of two separate cylindrically wound coils made of
copper or stainless tube. The evaporating refrigerant is in
one of the coils and the water to be cooled is in the other
coil. The water is cooled by the refrigerant in evaporator by
conduction. These water coolers are further classified as (a)
bottle type, (b) pressure type, and (c) self contained remote
type, these are discussed, in detail, as follows :
(a) Bottle type. As the name suggests, this type of
instantaneous water cooler employs a bottle or reservoir for
storing water to be cooled. No city main inlet connection is
required as it is normally used to cool water supplied in 25
litre glass bottles, which are placed on top of the unit, as
shown in Fig.5.
waste water and the length of the pipe coil comprising of
pre-cooler.
The pre-cooled water then enters the storage chamber and loses its heat to
Fig 6 pressure type
(c) Self contained remote type cooler. This type of cooler
employs a mechanical refrigeration system. The water
cooled from the remote cooler is supplied to desired
drinking place, away from the system. This type of
arrangement does not require extra space near the place of
work and is quite useful.
Fig 7 self-contained remote type
Fig 5 Bottle type
(b) Pressure type. In this type of instantaneous water
cooler, as shown in Fig.6, water is supplied under pressure.
The city main water enters the cooler through the inlet
connection at the rear of the cooler. It then passes through a
pre-cooler. The pre-cooler is cooled by the waste water of
the cooler. As the waste water temperature is low, it is
made use of cooling the supply water by passing through a
pipe coil wrapped around the drainage line. This
arrangement helps in reducing the cooling load for the
cooler. The amount of cooling depends upon the quantity of
10
3.2 Capacity of Water Coolers
The cooling load for the water cooler (Q) may be obtained
from the following relation:
Q=mw cp (Ti-To)
Where
mw= Rate of water consumption
cp= Specific heat of water
Ti= Inlet temperature of water, and
To= Outlet temperature of water.
The amount of cold water requirements under various
conditions is given. These figures are based on extensive
statistical survey. The refrigerants such as ammonia,
sulphur dioxide etc. are now-a-days not used because of
safety reasons. Generally R-12 is the most common
refrigerant up to one tonne refrigeration (1TR) capacity and
R-22 for two tonne refrigeration (2TR) capacity and
appropriate combination for larger size units.
The amount of wastage of cold water should be included
while estimating the amount of water consumption. Usually
Advanced Engineering and Applied Sciences: An International Journal 2015; 5(1): 7-14
heavy insulation around 40mm to 60mm thick glass wool
or thermocole is provided rendering insignificant heat
transfer through insulation.
4. PROBLEM STATEMENT
. Now a day’s refrigerator is not a luxury it has
become part of requirements in every middle and lower
middle class households. The refrigerator is used to store
food items, medicines, beverages and such other materials.
The useful life of foods and other items can be lengthened
due to storing at low temperatures. The household’s
refrigerator is also used for cool water and ice cubes. They
are usually specified by the internal gross volume and the
deep freezers volume. A storage temperature of 0 oC to 4oC
is satisfactory for the preservation of most of the fresh
foods.
The purpose of water cooler is to make water
available at a constant temperature irrespective of ambient
temperature. They are meant to produce cold water at about
7oC to 13oC for quenching the thirst of the people working
in hot environment. The warm or normal water can serve
the physical requirement of our system for the proper
functioning of the body organs but it does not quench the
thirst especially in hot summers.
In present days many families use refrigerator for
both food preservation and water cooling. A sample survey
conducted reveals that in many houses, the refrigerator
door is frequently opened just to get the cool water bottles.
Due to this frequent opening of the refrigerator door, the
ambient hot air keeps on entering into the refrigerator
cabin. It results in the increase of cabin temperature. To
reduce the cabin temperature the compressor runs most of
the time. It leads to more power consumption. Generally
six or seven liters of water is kept inside the refrigerator
cabin for drinking purpose. If we can keep the water
outside the refrigerator cabin, the space saved can be
utilized for keeping other products.
In the present work a domestic refrigerator is
modified to serve both the purposes of refrigerator as well
as water dispenser. Suitable design and operation
conditions were made to save space, initial cost and
maintenance cost.
5. EXPERIMENTAL SETUP
The domestic refrigerator and water dispenser works
on the vapour compression refrigeration system. The
domestic refrigerator is used to preserve the food items and
others. The water dispenser is used to cool water.
This project focuses to modify the domestic
refrigerator to serve both the purposes, as refrigerator and
also water dispenser. In this modified refrigerator the water
to be cooled is stored in the tank fixed outside the cabin, at
the top of the refrigerator. The water flows from the tank to
the accumulator located below the evaporator, through
10mm copper pipe line. The refrigerant flowing from the
evaporator outlet is made to flow through the pipe line
wound around the accumulator. Hence the water inside the
accumulator is cooled by the refrigerant flowing through
the pipe line. The cool water from the accumulator is taken
out from the outside of the refrigerator door by using a
flexible pipe between the accumulator outlet and tap, which
is arranged outside the refrigerator door. In this
11
arrangement the refrigerator is served as refrigerator as well
as water dispenser.
In order to know the performance characteristics of
the vapour compression refrigerating system the
temperature and pressure gauges are installed at each entry
and exit of the component.
Different types of tools are also used like tube cutter
- to cut the tubes, tube bender - to bend the copper tube to
the required angle, rivet set - to riveting process and
welding equipments - to joining process. Finally the
domestic refrigerator is fabricated as per the requirement of
the project. All the values of pressure and temperatures are
tabulated.
5.1 Experimental Set up
Domestic refrigerator selected for the project has the
following specifications
Refrigerant used: R-134a
Capacity of The Refrigerator: 160 liters
Compressor capacity: 0.16 H.P.
Compressor
Length 8.5 m
Diameter6.4 cms
Evaporator
Length 7.62 m
Diameter6.4 cms
Capillary
Length 2.428 m
Diameter0.8 mm
 A hole is made centrally at the top of the
refrigerator by using portable drilling machine
 A steel bowl is selected to store the water as well
as to give support to the water can, the steel bowl size is
: Diameter: 85mm
Height:
105mm
 A 10mm hole is made at the bottom of the steel
bowl to give connection to the water pipe
 A copper tube, to carry water from the steel bowl
is brazed to this hole
 Four L plates were welded at the bottom of the
steel bowl, to fix the bowl at the top of the refrigerator.
 The steel bowl was riveted at the top of the
refrigerator as shown in Fig 8
Fig 8 A view of steel bowl on top of refrigerator

A circular plate is riveted at the top of the steel
bowl, to support the water tank as shown in Fig 9.
Advanced Engineering and Applied Sciences: An International Journal 2015; 5(1): 7-14

The following diagrams illustrates the working
principle of present work
Fig 9 A view of circular plate

An accumulator is selected to store the water, the
sizes of accumulator is: Diameter: 34mm, Length:
280mm A copper tube coming from the evaporator outlet
is wound around the accumulator.

The accumulator is clamped at the bottom of
evaporator as shown in Fig 10.
Fig 10 A view of an accumulator to clamp the evaporator

A copper tube is connected the accumulator.

The evaporator set up is inserted into the body of
refrigerator.

A hole is made in the refrigerator door at
convenient location to tap water.

A tap is fitted to the door.

A flexible pipe is connected between the
accumulator and the tap.

Positioning of pressure gauges at suction and
discharge lines of compressor as shown in Fig 11
Fig 11 A view of pressure gauges position
12
Fig 12 Refrigerator cum chilled water dispenser
Fig 13 Principle of Refrigerator cum chilled water
dispenser
The following procedure is adopted for experimental setup
of the vapor compression refrigeration system
1.
The domestic refrigerator is selected, working on
vapor compression refrigeration system.
2.
Pressure and temperature gauges are installed at
each entry and exit of the components.
3.
Flushing of the system is done by pressurized
nitrogen gas.
4.
R 134a refrigerant is charged in to the vapor
compression refrigeration system by the following
process:
5.
The systematic line diagram for charging is shown
in the fig 14. it is necessary to remove the air from the
refrigeration unit before charging. First the valve V2 is
closed and pressure gauge P2, vacuum gauge V are fitted
as shown in the fig. the valve V5 is also closed and
valves V1, V4, V6 and V3 are opened and the motor is
started thus the air from the condenser receiver and
evaporator is sucked through the valve V1 and it is
discharged in to atmosphere through the valve V6 after
compressing it in the compressor the vacuum gauge V
indicates sufficiently low vacuum when most of the air is
removed in the system. The vacuum reading should be at
least 74 to 75 cm of Hg. If the vacuum is retained per
above an hour it may be concluded that the system is free
from the air. After removing the air the compressor is
stopped and valves V1 and V6 are closed, the valves V5,
Advanced Engineering and Applied Sciences: An International Journal 2015; 5(1): 7-14
V2 and V7 of the refrigerant cylinder are opened and
then the compressor is started whenever the sufficient
quantity of refrigerant is taken in to the system which
will be noted in the pressure gauges. The compressor is
stopped. The valves V7 and V5 are closed and valve V1
is opened the refrigerant cylinder is disconnected from
the system the pressure gauge is used to note the pressure
during the charging the system.
Calculation Performance Parameters
1. Net Refrigerating Effect (NRE) = h1-h4
=
249.3-114.3 = 135 kJ/kg
2. Mass flow rate to obtain one TR, kg/min.
mr = 210/NRE = 210/135 = 1.555 kg/min.
3. Work of Compression = h2-h1
= 273-249.3
= 23.67kJ/kg
4. Heat Equivalent of work of compression per TR
mr x (h2-h1) = 36.81 kJ/min
5. Theoretical power(compressor)= 0.6136 kW
6. Coefficient of Performance (COP) = h1-h4 / h2-h1 =
135/23.67 = 5.70
7. Heat to be rejected in condenser = h2-h3 = 158.7 kJ/kg
8. Heat Rejection per TR = (210/NRE) x (h2-h3) =
1.55X158.7 = 178.7 kJ/min
𝑫𝒊𝒔𝒉𝒄𝒂𝒓𝒈𝒆 𝑷𝒓𝒆𝒔𝒔𝒖𝒓𝒆
9. Compression Pressure Ratio =
=
𝑷𝒅
𝑷𝒔
𝑺𝒖𝒄𝒕𝒊𝒐𝒏 𝑷𝒓𝒆𝒔𝒔𝒖𝒓𝒆
=4.152
REFRIGERATOR CUM CHILLED WATER DISPENSER
Fig 14 systematic line diagram for charging
6.
Leakage tests are done by using soap solution, In
order to further test the condenser and evaporator
pressure and check purging daily for 12 hours and found
that there is no leakages which required the absolutely
the present investigation to carry out further experiment.
7.
Switch on the refrigerator and observation is
required for 1 hour and take the pressure and temperature
readings at each section.
8.
The performance of the existing system is
investigated, with the help of temperature and pressure
gauge readings.
9.
Temperature and pressure gauge readings are
taken and the performance is investigated.
6. CALCULATIONS
The various thermodynamic properties at state points of
domestic refrigerator are as follows
Temperatures
Compressor Suction Temp T 1
=10°C
Compressor Discharge Temp T2 =53°C
Condensing Temperature T3=
44°C
Evaporator Temperature T4 =
-2°C
Pressures
Compressor suction pressure P1
=0.68 bar
Compressor discharge pressure P2=12.4bar
Condenser pressure P3
= 12 bar
Evaporator pressure P4
=
0.8 bar
Enthalpies
From pressure-enthalpy chart for R-134a, enthalpy
values at state points 1,2,3,4. The state points are fixed
using pressure and temperature and each point.
h1
=249.3kJ/kg
h2
=273 kJ/kg
h3
=114.3 kJ/kg
h4
= 114.3 kJ/kg
13
Temperatures
Compressor Suction Temperature T 1= 13°C
Compressor Discharge Temp T2 =58°C
Condensing Temperature T3
=48°C
Evaporator Temperature T4
=
2°C
Pressures
Compressor suction pressure
P1=0.75 bar
Compressor discharge pressure
P2= 14 bar
Condenser pressure
P3
= 13.6 bar
Evaporator pressure
P4
= 0.9 bar
Enthalpies
From pressure-enthalpy chart for R-134a, enthalpy
values at state points 1,2,3,4. The state points are fixed
using pressure and temperature and each point.
h1
=
251.7 kJ/kg
h2
=
274.6 kJ/kg
h3
=
120.4 kJ/kg
h4
=
120.4 kJ/kg
Calculation Performance Parameters
1. Net Refrigerating Effect (NRE) = h1-h4
=
251.7-120.4 = 131.3kJ/kg
2. Mass flow rate to obtain one TR, kg/min.
3.
4.
5.
6.
7.
8.
9.
mr = 210/NRE=210/131.3=1.6 kg/min
Work of Compression = h2-h1 = 274.6-251.7 =
22.91kJ/kg
Heat Equivalent of work of compression per TR
mr x (h2-h1) = 1.6X22.91 = 36.66 kJ/kg
Theoretical power of compressor
= 36.66/60=
0.611 kW
Coefficient of Performance (COP)
= h1-h4 / h2h1= 131.3/22.91 = 5.72
Heat to be rejected in condenser = h2-h3 = 274.6120.4 = 154.2kJ/kg
210
Heat Rejection per TR =
x (h2-h3) = 1.6x 154.2 =
𝑁𝑅𝐸
178.8 kJ/min
𝐷𝑖𝑠ℎ𝑐𝑎𝑟𝑔𝑒 𝑃𝑟𝑒𝑠𝑠𝑢𝑟𝑒
𝑃
Compression Pressure Ratio =
= 𝑑
𝑆𝑢𝑐𝑡𝑖𝑜𝑛 𝑃𝑟𝑒𝑠𝑠𝑢𝑟𝑒
= 3.982
Advanced Engineering and Applied Sciences: An International Journal 2015; 5(1): 7-14
𝑃𝑠
7. RESULTS
Experimental investigations are carried out on
Refrigerator cum Water cooler and the results are compared
with a domestic refrigerator and the following are the
outcome for above investigation.
1.
The cop of the system is almost equivalent to
domestic refrigerator i.e. 5.7.
2.
The net refrigeration effect of combined system is
22% less than the domestic refrigerator.
3.
The mass flow of refrigerant per ton increases by
35%
4.
The Power required to drive the compressor
remains same.
5.
The heat rejected per ton of refrigerant in
condenser is same.
6.
The pressure ratio is decreases by 4% in the
experimental model.
8. CONCLUSIONS
The domestic refrigerator serves the purpose of cooling
food items and such other household requirements. Storing
of cold water in the refrigerator needs more no of openings
of the door.
In the present work a refrigerator is modified to serve
both purposes of refrigerator and also dispenser of cold
water.
It is found that a small modification saved power as
well as ease in operation and use of the refrigerator.
It is also found that the temperature inside the cabinet
are not much altered and C.O.P of the system did not
changed. It shows that chilled water is dispensed and even
then COP is not changed means that system gives superior
performance with this modification.
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Source of support: Nil; Conflict of interest: None declared
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Advanced Engineering and Applied Sciences: An International Journal 2015; 5(1): 7-14