group no. 2 evaporative condensaation

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A

PROJECT REPORT

on

EVAPORATIVE CONDENSATION IN WINDOW A.C.

Submitted in the partial fulfillment of the requirement for the award of the degree

of

BACHELOR OF ENGINEERING

in

MECHANICAL ENGINEERING

by

AUTI VISHAL ASHOK

CHAKAVE PRASHANT BABAN

GHOSALKAR SHRADDHA SUDHIR

SINGH GAURAV ARVIND

UNDER THE GUIDANCE OF

PROF. AMOL DAYMA

H.O.D. MECHANICAL DEPARTMENT (not required)

DEPARTMENT OF MECHANICAL ENGINEERING

SHIVAJIRAO S. JONDHLE COLLEGE OF ENGG.& TECHNOLOGY,

ASANGAON

2013-2014


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APPROVAL SHEET

The project report entitled EVAPORATIVE CONDENSATION IN WINDOW A.C.

submitted by

AUTI VISHAL ASHOK



SINGH GAURAV ARVIND

approved for partial fulfillment of requirement for the award of the degree of Bachelor of

Engineering in Mechanical Engineering.

PROF. AMOL DAYMA PROF. AMOL DAYMA

Head Guide

Department of Mechanical Engineering Department of Mechanical Engineering

Shivajirao S. Jondhle college of Engg.& Tech. Shivajirao S. Jondhle college of Engg.&

Tech

Asangaon Asangaon

Principal

Shivajirao S. Jondhle college of Engg.& Tech.

Asangaon

EXAMINERS

1. ____________

2.

____________

CONTENTS


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List of Figures

List of Tables

Definitions (Nomenclature)

(Abstract)

Chapter No

1

2.

3.

4

5

6

7

Title

INTRODUCTION

1.1 Air conditioning

1.2

Evaporative cooling

1.3 Existing VCR System

LITERATURE REVIEW

2.1 Vapor-compressionrefrigeration cycles

2.2

Compressors

2.3 Condensers

2.4 Expansion device

2.5

Evaporators

2.6 Refrigerant

2.7

Tonnes of refrigerantDESIGN PRINCIPLE

3.1 concept of evaporative condensation

EXPERIMENTATION

4.1 Aim

4.2 prior concept

4.3 New concept

4.4 apparatus

4.5 stepwise procedure

4.6 observation table

4.7 calculation

RESULTS AND CONCLUSION

EXPENDITURE

REFERENCE

age No.

1

6

23

26

35

38

40
http://en.wikipedia.org/wiki/Refrigeration_cyclehttp://en.wikipedia.org/wiki/Refrigeration_cycle


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Sr. no.

1.1

1.2

1.3

2.1

2.2

2.3

2.4

2.5

2.6

2.7

2.8

2.9

2.10

2.11

2.12

2.13

2.14

3.13.2

4.1

4.2

List of figure

Figure

window ac unit

evaporative cooling system

vapour compression system

p-h diagram of VCR system

reciprocating compressor

Rotary Compressor

centrifugal compressor

air cooled condensor

water cooled condenser

tube in tube water cooled condenser

Shell and coil condenser

Shell and tube condenser

Evaporative condenser

Capillary tube

Automatic or constant pressure expansion valve

Thermostatic expansion valve

Dry expansion evaporator

Example Setup For Evaporative Condensation

Block Diagram Of Evaporative Condenser

Pressure v/s Enthalpy Diagram of VCR system

Pressure v/s Enthalpy diagram of VCR system with sub-

cooling

(make list of tables and fig. in tabular for)


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List of Table

Sr No Table

4.1 Reading for Simple VCR System

4.2 Reading for Subcooling In VCR System

4.3 Cut-Off Time of Compressor

5.1 Comparisons of C.O.P

5.2 Comparison of Heat Rejected By Condenser

5.3 Comparison of Mass Flow Rate

Fig. no. Figure name Page no.

ACKNOWLEDGEMENT

we would like to take this opportunity to express my sincere and heartily thanks to

PROF. AMOL DAYMA, H.O.D. , Department of Mechanical Engineering for their

timely guidance and inspiration, without which my work would not have been

completed.


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we would like to thanks to DR.NEERAJ AGRAWAL , Associate Professor ,

Department of Mechanical Engineering , Dr. Babasaheb Ambedkar Technological

Institute , Lonere.For their valuable guidance about evaporative cooling system.

we would also like to thank him to giving me this opportunity to study the vast and

interesting field of tool condition monitoring.

submitted by :

AUTI VISHAL ASHOK



SINGH GAURAV ARVIND


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ABSTRACT

An air conditioner is amajor orhome appliance,system, ormechanism designed to

change the air temperature and humidity within an area (used for cooling and

sometimes heating depending on the air properties at a given time). The cooling is

typically done using a simple refrigeration cycle, but sometimesevaporation is used,

commonly for comfort cooling in buildings and motor vehicles.

As water is evaporated, energy is lost from the air, reducing the temperature. Two

temperatures are important when dealing with evaporative cooling systems.

In this system we going to used basic principal of evaporative cooling system in air

conditioning unit for increasing its efficiency.

Procedure used:

Main procedure is to work on coefficient of performance (C.O.P.) of air conditioningunit as per the basic principle in which cooling effect is obtain by evaporation of liquid

i.e. water.

Calculation and comparison of C.O.P. of following two systems :

Window air conditioner

Window air conditioner using evaporative condensation i.e. water cooled condesation

system

(for all pages use margin left 1.5, right 1, top 1 & bottom1)

(always use a single tab for new sentence)
http://en.wikipedia.org/wiki/Major_appliancehttp://en.wikipedia.org/wiki/Home_appliancehttp://en.wikipedia.org/wiki/Systemhttp://en.wikipedia.org/wiki/Mechanism_(technology)http://en.wikipedia.org/wiki/Cooling_(disambiguation)http://en.wikipedia.org/wiki/Refrigeration_cyclehttp://en.wikipedia.org/wiki/Evaporative_coolerhttp://en.wikipedia.org/wiki/Evaporative_coolerhttp://en.wikipedia.org/wiki/Refrigeration_cyclehttp://en.wikipedia.org/wiki/Cooling_(disambiguation)http://en.wikipedia.org/wiki/Mechanism_(technology)http://en.wikipedia.org/wiki/Systemhttp://en.wikipedia.org/wiki/Home_appliancehttp://en.wikipedia.org/wiki/Major_appliance


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DEFINITIONS

AC Air conditioner

oF Degrees Fahrenheit

EC Evaporative condenser

EER Energy Efficiency Ratio

EIR Electric input ratio

HVAC Heating, ventilation, and air conditioning

kW Kilowatt

kWh Kilowatt-hour

RECS Residential Energy Consumption Survey

TXV Thermostatic expansion valveW Watt

K kelvin


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CHAPTER 1

INTRODUCTION

(this page not required)


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Chapter 1

INTRODUCTION

1.1 Air conditioning (always use single tab for new sentence)

Air conditioning (often referred to AC or A/C) is the process of altering the properties

ofair (primarily temperature andhumidity) to more favorable conditions, typically with the

aim of distributing the conditioned air to an occupied space to improve comfort. More

generally, air conditioning can refer to any form of technology, heating, cooling, de-

humidification, humidification, cleaning, ventilation, or air movement, that modifies the

condition of air.

An air conditioner is amajor orhome appliance,system, ormechanism designed to

change the air temperature and humidity within an area (used for cooling and sometimes

heating depending on the air properties at a given time). Thecooling is typically done using a

simplerefrigeration cycle,but sometimesevaporation is used, commonly for comfort cooling

in buildings and motor vehicles. In construction, a complete system of

heating,ventilation and air conditioning is referred to as "HVAC".

Fig.1.1 : window ac unit
http://en.wikipedia.org/wiki/Airhttp://en.wikipedia.org/wiki/Temperaturehttp://en.wikipedia.org/wiki/Humidityhttp://en.wikipedia.org/wiki/Major_appliancehttp://en.wikipedia.org/wiki/Home_appliancehttp://en.wikipedia.org/wiki/Systemhttp://en.wikipedia.org/wiki/Mechanism_(technology)http://en.wikipedia.org/wiki/Cooling_(disambiguation)http://en.wikipedia.org/wiki/Refrigeration_cyclehttp://en.wikipedia.org/wiki/Evaporative_coolerhttp://en.wikipedia.org/wiki/Constructionhttp://en.wikipedia.org/wiki/Ventilation_(architecture)http://en.wikipedia.org/wiki/HVAChttp://en.wikipedia.org/wiki/HVAChttp://en.wikipedia.org/wiki/Ventilation_(architecture)http://en.wikipedia.org/wiki/Constructionhttp://en.wikipedia.org/wiki/Evaporative_coolerhttp://en.wikipedia.org/wiki/Refrigeration_cyclehttp://en.wikipedia.org/wiki/Cooling_(disambiguation)http://en.wikipedia.org/wiki/Mechanism_(technology)http://en.wikipedia.org/wiki/Systemhttp://en.wikipedia.org/wiki/Home_appliancehttp://en.wikipedia.org/wiki/Major_appliancehttp://en.wikipedia.org/wiki/Humidityhttp://en.wikipedia.org/wiki/Temperaturehttp://en.wikipedia.org/wiki/Air


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1.2 Evaporative cooling

An evaporative cooler (also swamp cooler, desert cooler and wet air cooler) is a device that

cools air through theevaporation of water. Evaporative cooling differs from typicalair

conditioning systems which usevapor-compression or absorption refrigeration cycles.

Evaporative cooling works by employing water's largeenthalpy of vaporization. The

temperature of dry air can be dropped significantly through the phase transition of liquid

water to water vapor (evaporation), which can cool air using much less energy

thanrefrigeration.In extremely dry climates, evaporative cooling of air has the added benefit

of conditioning the air with more moisture for the comfort of building occupants.

Air washers andwet cooling towers use the same principles as evaporative coolers but are

designed for purposes other than directly cooling the air inside a building. For example, an

evaporative cooler may be designed to cool the coils of a large air conditioning or

refrigeration system to increase its efficiency.

Fig.1.2 : evaporative cooling system

Evaporative cooling works because as warm air passes through a series of wet filter pads, the

water in the pads evaporates, therefore cooling the air passing through them. No refrigerants

are required, with their complex, energy intensive compression systems, in the production of

cold air used in evaporative cooling. This is why these systems run at 10% of the power of

air-con units.
http://en.wikipedia.org/wiki/Evaporationhttp://en.wikipedia.org/wiki/Air_conditioninghttp://en.wikipedia.org/wiki/Air_conditioninghttp://en.wikipedia.org/wiki/Vapor-compression_refrigerationhttp://en.wikipedia.org/wiki/Enthalpy_of_vaporizationhttp://en.wikipedia.org/wiki/Refrigerationhttp://en.wikipedia.org/wiki/Cooling_towerhttp://en.wikipedia.org/wiki/Cooling_towerhttp://en.wikipedia.org/wiki/Refrigerationhttp://en.wikipedia.org/wiki/Enthalpy_of_vaporizationhttp://en.wikipedia.org/wiki/Vapor-compression_refrigerationhttp://en.wikipedia.org/wiki/Air_conditioninghttp://en.wikipedia.org/wiki/Air_conditioninghttp://en.wikipedia.org/wiki/Evaporation


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1.3 EXISTING VCR SYSTEM

Fig.1.3 : vapour compression system

The existing cycle of consists of 4 basic parts viz. compressor, condenser, capillary

tube and an evaporator. The compressor used is a reciprocating compressor. An air cooled

condenser is used. Capillary tube which has reducing diameter is used in the system. It is the

cheapest expansion device available which satisfies the required condition of the refrigerantin the system. Refrigerant used in the present available system in the market is R22.

The hot vapour refrigerant from the evaporator flows into the compressor after taking heat

from the evaporator. The reciprocating compressor compresses this vapour refrigerant. This

increases the pressure and temperature of the refrigerant. The condition of the refrigerant at

the outlet of the compressor is superheated. This superheated vapour refrigerant is then

supplied to the condenser.

The refrigerant from the compressor is cooled inside the condenser. First few coils of

condenser cool the refrigerant by taking out the latent heat from the refrigerant. This reduces

the temperature and pressure of the refrigerant and the vapour refrigerant gets converted into

liquid refrigerant due to removal of latent heat from the refrigerant. Next some coils further

cool the refrigerant by removing sensible heat from the refrigerant. In this stage of the

condenser, the temperature of the refrigerant is reduced at constant pressure. The remaining

coils of the condenser coil further reduce the temperature and pressure of the refrigerant. This

stage is called sub cooling. This increases the refrigerant effect. Thus a system with sub

CAPILLARY TUBE

CONDENSOR

COMPRESSOR

EVAPORATOR


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cooling will have better coefficient of performance. The cooled liquid refrigerant from the

condenser is then passed through the capillary tube. This further reduces the temperature and

pressure of the refrigerant. This is due to the frictional resistance offered by a small diameter

tube. One of the biggest advantages using a capillary tube is that when the compressor stops

the refrigerant continues to flow inside the evaporator and equalizes the pressure between the

high side and low side of the system. This considerably decreases the static load on the

compressor. Thus a low starting torque motor can be used to drive the compressor. Since the

refrigerant charge in the capillary tube system is critical therefore no receiver is required.

This low pressure low temperature liquid refrigerant from the capillary tube flows into the

evaporator. due to the temperature difference between the liquid refrigerant and the

surrounding inside the evaporator, heat transfer takes place between the two. As we know

that the heat transfers from high temperature to low temperature, heat from the surrounding

which is at high temperature flows to refrigerant which is at low temperature. This increases

the pressure and temperature of the refrigerant. This causes phase transformation due to the

latent heat absorbed and the liquid refrigerant gets converted into vapour refrigerant. The hot

vapour refrigerant from the evaporator is then supplied to the compressor and the cycle is

repeated.

Another important component of the existing system is the circulating fan. The fan issituated along with the evaporator. The fan circulates the cold air that is generated in the

evaporator section in the entire refrigerating unit and produces cooling inside the entire

refrigerator. The malfunctioning of the fan can result in the breakdown of the refrigerating

unit as effective cooling will not be available in some section of the refrigerating unit.

A thermostat is also used which is connected to the overload and relay of a

compressor. It acts like a censor. The required temperature in the refrigerator is set in the

thermostat. When the set temperature inside the refrigerator is reached, the thermostat sends

signal to the compressor and the compressor stops. When the temperature inside the

refrigerator rises above the set temperature the thermostat sends signal to the compressor and

the compressor starts again. Defrosting is also provided in some of the refrigerating systems.


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CHAPTER 2

LITERATURE REVIEW



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Chapter 2

LITERATURE REVIEW

2.1 VAPOR-COMPRESSIONREFRIGERATION CYCLES

Vapor-compression refrigeration is one of the manyrefrigeration cycles and is the most

widely used method forair-conditioning of buildings and automobiles. It is also used in

domestic and commercial refrigerators, large-scale warehouses for chilled or frozen storage

of foods and meats, refrigerated trucks and railroad cars, and a host of other commercial and

industrial services.Oil refineries,petrochemical andchemicalprocessing plants, andnatural

gas processingplants are among the many types of industrial plants that often utilize largevapor-compression refrigeration systems.

Liquid saturation curve Vapour saturation curve

P2 3 Condensation 2 Condenser pressure

Wet region Superheated region

Sub-cooled region Expansion Compression

P1 4 Evaporation 1 Evaporator pressure

h3 = h4 Enthalpy h1 h2

fig. 2.1 : p-h diagram of VCR system

Refrigeration may be defined as lowering the temperature of an enclosed space by removing

heat from that space and transferring it elsewhere. A device that performs this function may

also be called aheat pump.

The vapor-compression uses a circulating liquidrefrigerant as the medium which absorbs and

removes heat from the space to be cooled and subsequently rejects that heat elsewhere.
http://en.wikipedia.org/wiki/Refrigeration_cyclehttp://en.wikipedia.org/wiki/Refrigeration_cyclehttp://en.wikipedia.org/wiki/Air_conditioninghttp://en.wikipedia.org/wiki/Oil_refineryhttp://en.wikipedia.org/wiki/Petrochemicalhttp://en.wikipedia.org/wiki/Chemical_planthttp://en.wikipedia.org/wiki/Natural_gas_processinghttp://en.wikipedia.org/wiki/Natural_gas_processinghttp://en.wikipedia.org/wiki/Heat_pump_and_refrigeration_cyclehttp://en.wikipedia.org/wiki/Refrigeranthttp://en.wikipedia.org/wiki/Refrigeranthttp://en.wikipedia.org/wiki/Heat_pump_and_refrigeration_cyclehttp://en.wikipedia.org/wiki/Natural_gas_processinghttp://en.wikipedia.org/wiki/Natural_gas_processinghttp://en.wikipedia.org/wiki/Chemical_planthttp://en.wikipedia.org/wiki/Petrochemicalhttp://en.wikipedia.org/wiki/Oil_refineryhttp://en.wikipedia.org/wiki/Air_conditioninghttp://en.wikipedia.org/wiki/Refrigeration_cyclehttp://en.wikipedia.org/wiki/Refrigeration_cycle


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All such systems have four components:

1.

acompressor

2. condenser

3.

athermal expansion valve(also called athrottle valve)

4.

an evaporator.

Circulating refrigerant enters the compressor in the thermodynamic state known as a

saturated vapor and is compressed to a higher pressure, resulting in a higher temperature as

well. The hot, compressed vapor is then in the thermodynamic state known as a superheated

vapor and it is at a temperature and pressure at which it can becondensed with either cooling

water or cooling air. That hot vapor is routed through a condenser where it is cooled and

condensed into a liquid by flowing through a coil or tubes with cool water or cool air flowingacross the coil or tubes. This is where the circulating refrigerant rejects heat from the system

and the rejected heat is carried away by either the water or the air (whichever may be the

case).

The condensed liquid refrigerant, in the thermodynamic state known as asaturated liquid,is

next routed through an expansion valve where it undergoes an abrupt reduction in pressure.

That pressure reduction results in the adiabaticflash evaporation of a part of the liquid

refrigerant. The auto-refrigeration effect of the adiabatic flash evaporation lowers thetemperature of the liquid and vapor refrigerant mixture to where it is colder than the

temperature of the enclosed space to be refrigerated.

The cold mixture is then routed through the coil or tubes in the evaporator. A fan circulates

the warm air in the enclosed space across the coil or tubes carrying the cold refrigerant liquid

and vapor mixture. That warm airevaporates the liquid part of the cold refrigerant mixture.

At the same time, the circulating air is cooled and thus lowers the temperature of the enclosed

space to the desired temperature. The evaporator is where the circulating refrigerant absorbs

and removes heat which is subsequently rejected in the condenser and transferred elsewhere

by the water or air used in the condenser.

To complete the refrigeration cycle, the refrigerant vapor from the evaporator is again a

saturated vapor and is routed back into the compressor.
http://en.wikipedia.org/wiki/Gas_compressorhttp://en.wikipedia.org/wiki/Condenser_(heat_transfer)http://en.wikipedia.org/wiki/Thermal_expansion_valvehttp://en.wikipedia.org/wiki/Throttlehttp://en.wikipedia.org/wiki/Boiling_point#Saturation_temperature_and_pressurehttp://en.wikipedia.org/wiki/Condensationhttp://en.wikipedia.org/wiki/Boiling_point#Saturation_temperature_and_pressurehttp://en.wikipedia.org/wiki/Flash_evaporationhttp://en.wikipedia.org/wiki/Evaporateshttp://en.wikipedia.org/wiki/Refrigeration_cyclehttp://en.wikipedia.org/wiki/Refrigeration_cyclehttp://en.wikipedia.org/wiki/Evaporateshttp://en.wikipedia.org/wiki/Flash_evaporationhttp://en.wikipedia.org/wiki/Boiling_point#Saturation_temperature_and_pressurehttp://en.wikipedia.org/wiki/Condensationhttp://en.wikipedia.org/wiki/Boiling_point#Saturation_temperature_and_pressurehttp://en.wikipedia.org/wiki/Throttlehttp://en.wikipedia.org/wiki/Thermal_expansion_valvehttp://en.wikipedia.org/wiki/Condenser_(heat_transfer)http://en.wikipedia.org/wiki/Gas_compressor


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2.2 COMPRESSORS

A refrigerant compressor as the name indicates is a machine used to compress the

vapour refrigerant from the evaporator and to raise its pressure so that the the corresponding

saturation temperature is higher than that of the cooling medium. It also continually circulates

the refrigerant through the the refrigerating system. Since the compression of refrigerant

requires some work to be done on it therefore a compressor must be driven by some prime

mover.

Classification of compressors:

1) According to method of compression

a) Reciprocating compressor

b) Rotary compressor

c) Centrifugal compressor

2) According to number of working strokes

a) Single acting

b) Double acting

3) According to number of stages

a) Single stage or single cylinder

b) Multi stage or multi cylinder

4) According to location of prime mover

a) Semi-hermetic compressor

b) Hermetic compressor


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2.2.1 Reciprocating compressor:

Fig. 2.2 reciprocating compressor

The compressor in which the refrigerant is compressed by reciprocating motion of

the piston is called reciprocating compressor. These compressors are used for refrigerants

which have comparatively low volume per kg and a large differential pressure. The

compression cylinders also known as stages, of which a particular design may have from one

to six or more, provide confinement for the process gas during compression. A piston is

driven in a reciprocating action to compress the gas. Arrangements may be of single-or dual-

acting design. (In the dual-acting design, compression occurs on both sides of the piston

during both the advancing and retreating stroke.) Some dual-acting cylinders in high-pressure

applications will have a piston rod on both sides of the piston to provide equal surface area

and balance loads. Tandem cylinder arrangements help minimize dynamic loads by locating

cylinders in pairs, connected to a common crankshaft, so that the movements of the pistons

oppose each other. Gas pressure is sealed and wear of expensive components is minimized


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through the use of disposable piston rings and rider bands respectively. These are formed

from comparatively soft metals relative to piston and cylinder/liner metallurgy or materials

such as polytetrafluoroethylene (PTFE). Process gas is drawn into the cylinder, squeezed,

contained and then released by mechanical valves that typically operate automatically by

differential pressures. Depending on system design, cylinders may have one or multiple

suction and discharge valves. Unloaders and clearance pockets are special valves that control

the percent of full load carried by the compressor at a given rotational speed of its driver.

Unloaders manipulate the suction valves action to allow the gas to recycle. Clearance pocket

valves alter the cylinder head space (clearance volume). They may be fixed or variable.

2.2.2 Rotary compressor

Fig.2.3 Rotary Compressor

In rotary compressors, the vapour refrigerant from the evaporator is compressed due to the

movement of the blades. The rotary compressors are positive displacement type compressors.

Since the clearance in the rotary compressor is negligible therefore they have high volumetric

efficiency. The rotary compressor is adaptable to direct drive by induction motors , gasoline

or diesel engines. The units are compact, relatively inexpensive, and require

operating attention and maintenance. They occupy a fraction of the space and weight

of a reciprocating machine of equivalent capacity. Rotary compressor units are classified


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into three general groups, slide vane-type, lobe-type, and liquid seal ring-type. The rotary

slide vane-type, has longitudinal vanes, sliding radially in a slotted rotor mounted

eccentrically in a cylinder. The centrifugal force carries the sliding vanes against the

cylindrical case with the vanes forming a number of individual longitudinal cells in the

eccentric annulus between the case and rotor. The suction port is located where the

longitudinal cells are largest. The size of each cell is reduced by the eccentricity of the rotor

as the vanes approach the discharge port, thus compressing the air.

2.2.3 Centrifugal compressors

Fig. 2.4 : centrifugal compressor

This compressor increases the pressure of low pressure vapour refrigerant to high

pressure using centrifugal force. The centrifugal compressors are generally used for

refrigerants that require large displacement and less condensing pressure. A single stage

centrifugal compressor in its simplest form consists of an impeller, to which a number of

curved vanes are fitted symmetrically. The impeller rotates in an air tight volute casing with

inlet and outlet points. The impeller draws in low pressure vapour refrigerant from the

evaporator. When the impeller rotates it pushes the vapour refrigerant from centre of the

impeller to its periphery by centrifugal force. the kinetic energy thus attained at the impeller

outlet is converted into pressure energy when the high velocity vapour refrigerant passes over

the diffuser. The volute casing collects the vapour refrigerant from the diffuser and it further

converts kinetic energy into pressure energy before it leaves the refrigerant to the evaporator.


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The centrifugal compressor has no valves, pistons and cylinder. The only wearing parts are

the main bearings.

2.3 CONDENSERS

Condenser is an important device used in high pressure side of a refrigeration system.

Its function is to remove heat of hot vapour refrigerant discharged from the compressor. The

hot vapour refrigerant consist of heat absorbed by the evaporator and the heat of compression

added by mechanical energy of compressor motor. The heat from hot vapour refrigerant in a

condenser is removed first by transferring it to the walls of the condenser tubes and then from

the tubes to the condensing or cooling medium. The condensing medium may be water or air

or combination of the two. The selection of condenser depends upon capacity of refrigeration

system, the type of refrigerant used and type of cooling medium available.

The condenser cools the refrigerant in following three stages:

a) The superheated vapour is cooled to saturation temperature corresponding to pressure

of the refrigerant.

b)

Saturated vapour refrigerant gives up its latent heat and is condensed to a saturated

liquid refrigerant.

c)

The temperature of the liquid refrigerant is reduced below its saturation temperature

in order to increase the refrigerating effect.

Classification of condensers:

a) Air cooled condenser

b)

Water cooled condenser

c) Evaporative condenser

2.3.1 Air cooled condenser


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Fig. 2.5 : air cooled condensor

Air cooled condenser is one in which the removal of heat is done by air. It consist of copper

or steel tubing through which the refrigerant flows. The size of tube usually ranges from 6mm

to 18mm outside diameter. Generally copper tubes are used because of its excellent heat

transfer ability. The tubes are usually provided with plate type fins to increase the surface

area for heat transfer. The fin spacing is quite wide to reduce dust clogging. The condensers

with single row of tubing provide most efficient heat transfer. Thus is because the air

temperature rises as it passes through each row of tubing. However single row tubing requires

more space than multi row condensers. Air cooled condensers may have two or more rows oftubing. More than eight rows of tubing is not efficient because air temperature will be too

close to the condenser temperature to absorb any more heat after passing through eight rows

of tubing.

Types of air cooled condensers:

a) Natural convection air cooled condenser

b)

Forced convection air cooled condenser

2.3.2 Water cooled condenser


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Fig. 2.6 : water cooled condenser

A water cooled condenser is one in which water is used as the condensing medium.

they are always preferred when an adequate supply of clear and inexpensive water and meansof water disposal are available. These condensers are commonly used in commercial and

industrial refrigerating units. The water cooled condensers may use either of the two systems:

a) Waste water system

b) Recirculated water system

The water cooled condensers operate at a lower condensing temperature than an air cooled

condenser. this is because the supply water temperature is normally lower than the ambient

air temperature. But the difference between condensing and cooling medium temperatures is

normally the same. Thus the compressor for a water cooled condenser requires less power

for the same capacity.

Types of water cooled condenser:

a. Tube in tube or double tube condenser


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Fig. 2.7 : tube in tube water cooled condenser

b. Shell and coil condenser

Fig.2.8 : Shell and coil condenser

c. Shell and tube condenser


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Fig. 2.9 : Shell and tube condenser

2.3.3 Evaporative condenser


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Fig. 2.10 : Evaporative condenser

The evaporative condenser uses both air and water as condensing medium to condense hot

vapour refrigerant to liquid refrigerant. These condenser performs combined functions of

water cooled condenser and cooling tower.

The water is pumped from a sump to spray header and sprayed through nozzles over

condenser coils through which the hot vapour refrigerant from the compressor is passing. The

heat transfers from refrigerant through the condensing tube walls and into the water that is

wetting the outside surface of tubes. At the same time a fan draws air from the bottom side of

condenser and discharged out at top of condenser. The air causes the water from the coil

surface to evaporate and absorb latent heat of evaporation from remaining water to cool it.

The cold water that drops down into a sump is recirculated. The eliminator is provided above

spray header to stop particles of water escaping along with the discharged air.

2.4 EXPANSION DEVICES


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The expansion device also known as metering device or throttling device is an important

device that divides the high pressure side and low pressure side of a refrigerating system. it is

connected between the compressor and the evaporator. The expansion device performs the

following functions:

1)

It reduces the high pressure liquid refrigerant to low pressure liquid refrigerant before

being fed to the evaporator.

2) It maintains the desired pressure difference between high and low pressure sides of the

system. So that the liquid refrigerant vapourises at the desired pressure in the

evaporator.

3) It controls the flow of refrigerant according to the load on the evaporator.

The expansion devices used with dry expansion evaporators are called expansion valve and

the expansion devices used with flooded evaporators is known as float valve.

Types of expansion devices are as follows:

1)

Capillary tube

2) Hand operated expansion valve

3) Automatic or constant pressure expansion valve

4)

Thermostatic expansion valve5) Low side float valve

6) High side float valve

Some important types of expansion devices are explained below:

2.4.1 Capillary tube

Fig. 2.11 : capillary tube


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The capillary tube is used as expansion device in small capacity hermetic sealed refrigerating

units such as domestic refrigerators, water coolers, air conditioners and freezers. It is a copper

tube of small internal diameter and varying length depending upon the application. The inside

diameter of tube used in refrigeration work is generally about 0.5 to 2.25mm and length

varies from 500mm to 5000mm. it is installed in the liquid line between condenser and the

evaporator. A fine mesh is provided at the inlet of the tube in order to protect it from any

contaminants. A small filter drier is used on some system to provide additional freeze up

applications.

In operation, liquid refrigerant from condenser enters capillary tube. Due to frictional

resistance offered by the small diameter tube pressure drops. The frictional resistance is

directly proportional to the length and inversely proportional to the diameter. The cost of

capillary tube is less than all other forms of expansion devices. Also the refrigerant charge in

a capillary tube system is critical, therefore no receiver is necessary.

2.4.2 Automatic or constant pressure expansion valve

Fig. 2.12 : Automatic or constant pressure expansion valve

Automatic expansion valve is also known as constant pressure expansion valve because it

maintains constant evaporator pressure regardless of the load on the evaporator.


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The automatic expansion valve consist of a needle valve and a seat , a metallic diaphragm,

spring and a adjusting screw. The opening and closing of the valve depends upon two

opposing forces acting on diaphragm:

1)

The spring pressure and the atmospheric pressure on top of the diaphragm

2)

The evaporator pressure acting below the diaphragm.

When the evaporator pressure falls down, the diaphragm moves downwards to open the

valve. This allows more liquid refrigerant to enter into the evaporator and thus increasing the

evaporator pressure till the desired evaporator pressure is reached. On the other hand when

the evaporator pressure rises, the diaphragm moves upwards to reduce the opening of the

valve. This decreases the flow of liquid refrigerant in the evaporator which in turn lowers the

evaporator pressure till the desired evaporator pressure is reached.

When the compressor stops, the liquid refrigerant continues to flow inside the evaporator and

increases the pressure inside the evaporator. The increase in the evaporator pressure causes

the diaphragm to move upwards and the valve is closed. It remains closed until the

compressor starts again and reduces the pressure in the evaporator.

2.4.3 Thermostatic expansion valve

Fig. 2.13 : Thermostatic expansion valve

The thermostatic expansion valve consists of an additional feature that is of feeler or thermal

bulb which is mounted on the suction line near outlet of the evaporator coil. This feeler bulb


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is partially filled with same liquid refrigerant as used in the refrigerating system. The opening

and closing of the valve depends upon following forces acting on the diaphragm:

1) The spring pressure acting on the bottom of the diaphragm.

2)

The evaporator pressure acting on the bottom of the diaphragm.

3)

The feeler bulb pressure acting on top of the diaphragm.

Since the feeler bulb is installed on the suction line, therefore it will be at the same

temperature as the refrigerant at that point.

If the load on the evaporator increases, it causes the liquid refrigerant to boil faster in the

evaporator coil. The temperature of the feeler bulb increases due to early vapourisation of the

liquid refrigerant. Thus the feeler bulb pressure increases and the pressure is transmitted

through the capillary tube to the diaphragm. The diaphragm moves downwards and opens the

valve to admit more quantity of liquid refrigerant to the evaporator. This continues until

pressure equilibrium on the diaphragm is reached. On the other hand, when the load on the

evaporator decreases, less liquid refrigerant evaporates in the evaporator. The excess liquid

refrigerant flows towards the evaporator outlet which cools the feeler bulb due to which

feeler bulb pressure decreases. The low feeler bulb pressure through the capillary tube is

transmitted to the diaphragm and it moves upwards. This reduces the opening of the valve

and thus the flow of liquid refrigerant to the evaporator. The evaporator pressure decreases

due to reduced quantity of liquid refrigerant flowing in the evaporator. This continues till the

evaporator pressure and the spring pressure maintains equilibrium with feeler bulb pressure.

2.5 EVAPORATORS

The evaporator is an important device used in low pressure side of a refrigeration

system. The liquid refrigerant from the expansion valve enters into the evaporator where it

boils and changes into vapour. The function of the evaporator is to absorb heat from the

surrounding location or medium which is to be cooled, by means of a refrigerant. The

temperature of the boiling refrigerant in the evaporator must always be less than that of the

surrounding medium so that the heat flows to the refrigerant. The evaporator becomes cold

and remains cold due to following reasons:

1) The temperature of the evaporator coil is low due to the low temperature of the

refrigerant inside the coil.


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2) The low temperature of the refrigerant remains unchanged because any heat it absorbs

is converted to latent heat as boiling proceeds.

The evaporator is also known as a cooling coil or a chilling coil or a freezing coil.

Classification of evaporators:

1) According to type of construction

a) Bare tube coil evaporator

b) Finned tube evaporator

c) Plate evaporator

d) Shell and tube evaporator

e) Shell and coil evaporator

f) Tube in tube evaporator

2) According to the manner in which the liquid refrigerant is fed:

a) Flooded evaporator

b) Dry expansion evaporator

3) According to mode of heat transfer

a) Natural convection evaporator

b) Forced convection evaporator

4) According to operating conditions:

a) Frosting evaporator

b) Non-frosting evaporator

c) Defrosting evaporator


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Some important types of evaporators are explained below:

2.5.1 Flooded evaporators

In flooded evaporators, a constant liquid refrigerant level is always maintained. Afloat control valve is used as expansion device which maintains a constant liquid level inside

the evaporator. The liquid refrigerant from the receiver passes through the low side float

control valve and accumulator before entering the evaporator. The accumulator serves as

storage for liquid refrigerant. It maintains a constant liquid level inside the evaporator and

helps to separate the liquid refrigerant from the vapour returning to the compressor. Due to

the heat supplied by the surrounding the liquid evaporates and the liquid level inside the

evaporator falls down. The accumulator supplies more liquid to the evaporator in order to

keep the liquid refrigerant in the evaporator at proper level. In this way the level of liquid

refrigerant in the accumulator also falls down. Since the float within the float chamber rests

on liquid refrigerant at the same level as in the accumulator, therefore the float also falls

down and opens the float valve. Now the liquid refrigerant from receiver is admitted to the

accumulator. As the liquid level in the accumulator rises and reaches to the constant level the

float also rises with it till the float control valve closes.

The advantage of the flooded evaporator is that the whole surface of the evaporator

coil is in contact with the liquid refrigerant under all load conditions. Thus it gives high heat

transfer rate than a dry expansion evaporator of the same size. However the flooded

evaporator is more expensive to operate as it requires more refrigerant charge. The flooded

evaporator has many industrial applications especially is chemical and food processing

industries.

2.5.2 Dry expansion evaporator

Fig. 2.14 : Dry expansion evaporator


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Dry expansion evaporator use very little refrigerant as compared to flooded evaporators

having same coil volume. The dry expansion evaporators are only one-fourth or one-third

filed with liquid refrigerant. In dry expansion valve the liquid refrigerant from the receiver is

fed by an expansion valve to the evaporator coil. The expansion valve controls the rate of

flow of liquid refrigerant in such a way that all the liquid refrigerant is vapourised by the time

it reaches the end of the evaporator coil or at suction line to the compressor. The vapour is

also superheated to a limited extent.

The rate at which the liquid refrigerant is fed to the evaporator generally depends

upon the rate of vapourisation and increases or decrease as the load on it increases or

decreases. When the cooling load on the evaporator is light the quantity of the liquid

refrigerant inside the evaporator is small. If the coil diameter is small the bubbles can cause

dry areas on the interior of the coils. These dry areas reduce the rate of heat transfer. Thus the

evaporator efficiency decreases as the dry areas increases that is when the load on the

evaporator is light. If the cooling load on the evaporator is heavy the expansion valve allows

large quantity of liquid refrigerant into the evaporator coil in order to accommodate the heavy

load. In this case the liquid and the vapour separate. The liquid refrigerant flows along the

bottom of the coil and the vapour rises towards the top. in this way the evaporator efficiency

is greatest. However this efficiency depends upon the diameter of the evaporator tube,quantity of the refrigerant in the evaporator and velocity of the liquid refrigerant within the

evaporator coil.

2.6 REFRIGERANTS

The refrigerant is a heat carrying medium which during their cycle in the refrigeration

system absorbs heat from a low temperature system and discards the heat to high temperature

system. The natural ice and mixture of ice and salt were the first refrigerants. The suitability

of refrigerant for particular application is determined by its physical, thermodynamic,

chemical properties and by various practical factors. There is no one refrigerant that can be

used for all types of applications. There is no ideal refrigerant. If one refrigerant has certain

good advantages it will have some disadvantages also.

An ideal refrigerant must have following properties:

1)

low boiling point

2) High critical temperature


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3) High latent heat of vapourisation

4) Low specific heat of liquid

5)

Low specific volume of vapour.

6) Non-corrosive to metal

7) Non flameable and nonexplosive

8)

Non-toxic

9) Low cost

10) Easy to liquify at moderate temperature and pressure

Classification of refrigerants:

1) Primary refrigerants

The refrigerants which directly take part in the refrigeration system are called as

primary refrigerant.

The primary refrigerants are further classified as:

a) Halo-carbon refrigerants

Commonly used halo-carbon refrigerants are: R11, R12, R13, R21 and R22.

b) Azeotrope refrigerants

Various Azeotrope refrigerants used are: R500, R502, R503 and R504.

c) Inorganic refrigerants

Commonly used inorganic refrigerants are: R118, R717, R729, R744 and R764

d) Hydro-carbon refrigerants:

Various hydro-carbon refrigerants are: R170, R290, R600, R1130 and R1150

2) Secondary refrigerants

The refrigerant that is first cooled by primary refrigerant and then is used for cooling

purpose is known as secondary refrigerants.

Brine is an example of secondary refrigerant.


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2.7 Tonne Of Refrigeration

Thecooling capacity of refrigeration systems is often defined in units called "tons of

refrigeration". The most common definition of that unit is: 1ton of refrigeration is the rate of

heat removal required to freeze ashort ton (i.e., 2000pounds,907.2 kg) of water at 32F (0

C) in 24 hours. Based on the heat of fusion for water being 144Btuper pound, 1 ton of

refrigeration = 12,000 Btu/h = 12,660 kJ/h = 3.517 kW. Most residential air conditioning

units range in capacity from about 1 to 5 tons (3.5 - 18 kW) of refrigeration.

A much less common definition is: 1tonne of refrigeration is the rate of heat removal

required to freeze ametric ton (i.e., 1000 kg) of water at 0C in 24 hours. Based on theheat

of fusionbeing334.9 kJ/kg, 1 tonne of refrigeration = 13,954 kJ/h = 3.876 kW. As can be

seen, the definition of 1 tonne of refrigeration in metric units is 10 percent larger than 1 ton of

refrigeration using old imperial units.
http://en.wikipedia.org/wiki/Cooling_capacityhttp://en.wikipedia.org/wiki/Tonhttp://en.wikipedia.org/wiki/Short_tonhttp://en.wikipedia.org/wiki/Pound_(mass)http://en.wikipedia.org/wiki/Fahrenheithttp://en.wikipedia.org/wiki/Heat_of_fusionhttp://en.wikipedia.org/wiki/Btuhttp://en.wikipedia.org/wiki/Tonnehttp://en.wikipedia.org/wiki/Tonnehttp://en.wikipedia.org/wiki/Celsiushttp://en.wikipedia.org/wiki/Heat_of_fusionhttp://en.wikipedia.org/wiki/Heat_of_fusionhttp://en.wikipedia.org/wiki/Heat_of_fusionhttp://en.wikipedia.org/wiki/Heat_of_fusionhttp://en.wikipedia.org/wiki/Celsiushttp://en.wikipedia.org/wiki/Tonnehttp://en.wikipedia.org/wiki/Tonnehttp://en.wikipedia.org/wiki/Btuhttp://en.wikipedia.org/wiki/Heat_of_fusionhttp://en.wikipedia.org/wiki/Fahrenheithttp://en.wikipedia.org/wiki/Pound_(mass)http://en.wikipedia.org/wiki/Short_tonhttp://en.wikipedia.org/wiki/Tonhttp://en.wikipedia.org/wiki/Cooling_capacity


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CHAPTER 3

DESIGN PRINCIPLE 0F PROJECT



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3. DESIGN PRINCIPLE 0F PROJECT

3.1 concept of evaporative condensation

Evaporative condensers improve the heat rejection process by using the cooling effect of

evaporation. Water is sprayed over the condensing coil from above while air is

simultaneously blown up through the coil from below to naturally lower the condensing

temperature. The lower condensing temperature reduces compressor workload. As a result,

your system operates more efficiently than air cooled alternatives and it uses far less

energy. In fact, the reduced compressor kW draw (25 to 30%) coupled with demand charge

savings (up to 30% of a utility bill in some cases) can result in operating cost savings of more

than 40% versus air-cooled condensers. But the benefits do not stop here:

The reduced compressor kW draw can lower electrical installed costs because wire

sizes, disconnects and other electrical controls can be reduced.

Repair costs and downtime can be reduced and component life can increase because

the compressors work against a smaller pressure differential versus air-cooled

condensers.

Fig. 3.1 : Example Setup For Evaporative Condensation


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In the evaporative-cooled condensing process, water is sprayed over the condenser coil as the

condenser fans draw air across the coil to evaporate the spray and cool the refrigerant tubes

toward the ambient wet bulb temperature. Unlike an air-cooled condenser which rejects heat

from the

refrigerant to the air at the ambient dry bulb temperature, an evaporative cooled condenser

rejects heat from the refrigerant to the water at the wet bulb temperature which can be 15 to

25F lower than dry bulb. The lower condensing temperature means that the evaporative-

cooled condenser can reject more heat than an air-cooled condenser, while requiring less

compressor work and consuming less energy. As a result an evaporative cooled

condenser can be 20% to 40% more efficient than a comparable air-cooled condenser. In

addition the electrical service to the unit can be sized for lower amps, reducing installedcosts.

Fig 3.2 : Block Diagram Of Evaporative Condenser


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CHAPTER 4

EXPERIMENTATION



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4. EXEPERIMENTATION

Aim :

To determine coefficient of performance (c.o.p.) and heat rejection Qr in condenser of

window AC unit by;

1. Air cooled condenser

2. Evaporative condensation

Prior concept:

Concept of simple vapor compression cycle used in window ac.

Evaporative cooling system

New concept:

Subcooling in VCR system .

Evaporative condensation (i.e. water + air cooled condenser ) system used in VCR system

Apparatus :

1. Window ac unit

2. Evaporative cooling system

-evaporative pad

-water distribution system

Procedure :

1. Study the complete VCR system used in domestic AC system

2.

Install AC unit in closed room having 150 sq ft area

3. Take readings of every point in VCR system at different room temperature .

4. Install evaporative cooling system for water cooled condenser in window ac unit .


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5. Again took readings at different room temperature in same area and atmospheric

condition.

6.

Prepare observation table for readings at various room temperature.

7. calculate COP (coefficient of performance) and Heat lost by refrigerant in

condensation process i.e heat rejected by condenser

Diagram :


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Observation table :

1. Reading using simple VCR system

Room tempC

Evaporativetemp

Compressortemp

Condensatetemp

Expansiontemp

16 16 80 40 21

20 20 95 47 26

24 24 104 58 30

Table 4.1 : reading for simple VCR system

2.

readings using subcooling in VCR system (i.e. evaporative condensation)

Room temp

C

Evaporative

temp

Compressor

temp

Condensate

temp

Expansion

temp

16 16 60 33 21

20 20 75 36 26

24 24 95 42 30

Table 4.2 : reading for subcooling in VCR system

3.

cut off time of compressor ( from 34 C room temp)

Room temp Cut-off time during simple VCR

system

(min)

Cut-off time during VCR system

with subcooling

(min)

24 12 10.30

20 6.35 5.2

16 4.8 4

Table 4.3 : cut-off time of compressor


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Calculation :

Refrigerant : R22

Power consumption : 1235 W

Cooling capacity : 1 Tr = 3.5 kw = 3457 Watt

Energy efficiency : 2.8 EER

Calculation on the basis of P-h diagram

Case 1 : calculation for simple VSR system

Consider following p-h diagram,

Liquid saturation curve Vapour saturation curve

P2 3 Condensation 2 Condenser pressure

Wet region Superheated region

Sub-cooled region Expansion Compression

P1 4 Evaporation 1 Evaporator pressure

h3 = h4 Enthalpy h1 h2

Fig. 4.1 : Pressure v/s Enthalpy Diagram of VCR system

Diagram is of ideal theoretical process for conventional system of domestic refrigerator

where we use Air-cooled condenser to cool high pressure, high temperature refrigerant. In

this case we are assuming that, point 1 is on the vapor saturated curve but in actual process it

will shift slightly in superheated region. Also we have considered that condenser cools the

refrigerant upto liquid saturation curve and whole refrigerant is saturated liquid at point 3.


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Hence as describe before,

Process 1-2 is Compression (Assuming isentropic process which is practically not possible)

consuming 1235 watt power, producing Refrigeration effect of 3457 watt.

Description of points and lines on above curve

Sample calculation for room temperature = 16

Evaporator Temperature: 16 C

Condensation Temperature: 40 C (check suffix and prefix in report)

Form Mathur-Mehta chart,

h1 = 410 KJ/Kg ,

h2 = 428 KJ/Kg

Wc = mr ( h2h1 ) ....(1)

Putting all the values in above equation (1)

1235 = mr (428410) * 10^3

Therefore,

mr = 0.068 kg/s/Tr

Aslo, Refrigeration effect or Cooling Effect,

RE = 3457 watt

Therefore,

RE = mr (h1h4)

3457 = 0.068 (410h4)*10^3

h4 = 359.16 KJ/Kg

This is sufficient data to plot complete diagram on P-h chart.

COP = RE / WC


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= (410-359.16) / (428-410)

= 2.8

Now Heat lost by refrigerant in condensation process i.e heat rejected by condenser is,

Qr = mr (h2h3)

= 0.0686 ( 428250 ) *10^3

Qr = 12210.8 watt .(2)

This is exact amount of heat that condenser has to escape to surrounding so that, refrigerant

will produce desired effect. Now if we increase the heat lost in condenser by

EVAPORATIVE CONDENSATION then we can get more cooling effect in refrigerator.

This was calculation for Air- cooled condenser in use.

Case 2 : calculation for VCR with subcooling

Whenever we use water cooled condenser then, more heat can be possibly removed from

refrigerant and point 3 can be shifted to sub-cooled region.

Consider following diagram of P-h chart for water cooled condenser in use.

P2 3 3 2

Pressure Condensation Condenser pressure

Compression

Sub-cooled Region Expansion Superheated region

Wet region P1 4 4 1 Evaporator pressure

Evaporation

h4=h3 Enthalpy h1 h2

Fig 4.2 Pressure v/s Enthalpy diagram of VCR system with sub-cooling


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Evaporator Temperature: 16 C

Condensation Temperature: 33 C

Degee of subcoolig = 40-33 = 7 C

Cpl= 4.187 KJ/KGK

Form R.S.Khurmi chart,

h1 = 410 KJ/Kg

h2 = 424 KJ/K

h3= 250 kj/kgk

Enthalpy at 3 ,

h3=h3 - Cpl (t3-t3)

=2504.187(40-33)

h3=216.295 kj/kg k

Wc = mr ( h2h1 ) ....(3)

Putting all the values in above equation (3)

1235 = mr (424 - 410)

Therefore,

mr = 0.0882 kg/s/Tr

Aslo, Refrigeration effect or Colling Effect,

RE = 3457 watt

Therefore,

RE = mr (h1h4)

3457 = 0.0882 (410h4)*10^3

h4 = 370.80 KJ/Kg


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This is sufficient data to plot complete diagram on P-h chart.

COP = RE / WC

= (410-370.80) / (424-410)

= 2.8

Now Heat lost by refrigerant in condensation process i.e heat rejected by condenser is,

Qr = mr (h2h3)

= 0.0882 ( 424216.295 ) *10^3

Qr = 18319.58 watt (4)

According to (2) and (4) it has been shown that, calculation according two different charts

gives us different values of Heat rejected in condenser.

For further calculation we shall take value of Qr that we have calculated from Mathur

Mehta chart.

As said before whenever we shall use water cooled condenser then as shown in above

diagram point 3 will shift into sub cooled region. But how much will that shift is

unpredictable before calculation so just to start with the process, we shall assume that water

takes all the heat from refrigerant instead of air without any loss and amount is similar to that

in previous case.


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CHAPTER 5

RESULTS AND CONCLUSION



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5. RESULT AND CONCLUSION

Results :

1.

Coefficient of performance in simple VCR system and subcooling in VCR system are as

follow :

ROOM Temp Coefficient of performance (cop)

Simple VCR Subcooling in VCR

16 2.88 2.79

20 2.79 2.82

24 2.79 2.798

Table 5.1 : comparisons of c.o.p

2. Heat rejected by condenser (kw) in simple VCR system and subcooling in VCR system

are as follow :

ROOM Temp Heat rejected by condenser (kw)


16 11.75 17.97

20 11.662 23.67

24 34.48 76.78

Table 5.2 : comparison of heat rejected by condenser

3. Mass flow rate (kg/sec/Tr) in simple VCR system and subcooling in VCR system are as

follow :

ROOM Temp Mass flow rate (kg/sec/Tr)


16 0.0686 0.0882

20 0.0686 0.10292

24 0.2403 0.3183

Table 5.3 : comparison of mass flow rate


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CONCLUSION :

1. There is no more difference in coefficient of performance by using subcooling VCR

system as compare to simple VCR system.

2.

In calculation according two different charts gives us different values of Heat rejected

in condenser at different room temperature.

3. Mass flow rate (kg/sec/Tr) is increased in subcooling in VCR system as compare to

simple VCR system.

4. By using subcooling in VCR system water takes all the heat from refrigerant instead

of air without any loss and amount is similar to that in previous case.

5. Because of increase in mass flow rate and heat rejection in condenser , time required

for cooling desired area get reduced . i.e. increased in cooling rate of unit.

FUTURE SCOPE :

This is attempt to increase the cooling capacity of standard household window A.C. system

while reducing energy usage. This is accomplished by evaporative cooling of the air entering

the condenser (outside part) unit. The lower temperature allows the condenser to operate at

lower temperature and pressure. This reduced pressure allows ac compressor to pump

additional refrigerant and decrease the energy useage .

By adopting these system , indirectly we save energy by reducing compressor work.


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CHAPTER 6

EXEPENDTURE



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6. EXPENDITURE

sr.no. Componenet Cost

1 Window a.c. unit 4000/-

2 Table 1400/-

3 Cooler Motor 150 /-

4. Other equipment (pipe, wire , socket, thermacol sheet etc. ) 500/-

5. Mechanic charges 400/-

Total 6450/-


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CHAPTER 7

REFERANCE


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REFERENCES

1. DR.NEERAJ AGRAWAL , Associate Professor and their M.TECH Student

department of mechanical engineering

Dr. Babasaheb Ambedkar technological Institute , lonere.

2 Textbook of Refrigerating and Air conditioning

Author: R.S Khurmi

Published by: S. Chand, Delhi

3 . refrigerant and psychometric properties

(tables and charts)

Mathur & Mehta

4 textbook of refrigeration and air conditioning

Author: Anantnarayan

5. S.S. Lifestyle Pvt. Ltd. , Mumbai

Dealers of evaporative pad

6. www.google.com

7. www.wikipedia.com

8 . technical papers on evaporative condensation and evaporative cooling system


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group no. 2 evaporative condensaation

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