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ELEMENTS OF MECHANICAL ENGINEERINGELEMENTS OF MECHANICAL ENGINEERING

Refrigeration &

Air – Conditioning

LOCATION & ATMOSPHERE OF GUJARATLOCATION & ATMOSPHERE OF GUJARAT

HIGHEST TEMPERATURE IN SUMMER 46 CHIGHEST TEMPERATURE IN SUMMER 46 C

AVERAGE TEMPERATURE IN MONSOON 26 C TO 32 C AVERAGE TEMPERATURE IN MONSOON 26 C TO 32 C

REQUIRED LOWERED TEMPERATURE FOR REQUIRED LOWERED TEMPERATURE FOR FOLLOWING PURPOSEFOLLOWING PURPOSE

FOOD PRESERVATIONFOOD PRESERVATIONLIKE DAIRY PRODUCT, VEGETABLES, FRUITS, MEATS, LIKE DAIRY PRODUCT, VEGETABLES, FRUITS, MEATS, FISH, ICE CREAM PRODUCTS ETC. FISH, ICE CREAM PRODUCTS ETC.


TRANSPORTATION OF FOOD STUFFTRANSPORTATION OF FOOD STUFFLIKE DAIRY PRODUCT, VEGETABLES, FRUITS, MEATS, LIKE DAIRY PRODUCT, VEGETABLES, FRUITS, MEATS, FISH, ICE CREAM PRODUCTS ETC. FISH, ICE CREAM PRODUCTS ETC.


COOLING OF WATERCOOLING OF WATER


FOR MAKING ICEFOR MAKING ICE

REFRIGERATIONREFRIGERATION

THE METHOD OF REDUCING THE TEMP. OF A SYSTEM BELOW THE SURROUNDING TEMP.AND MAINTAIN IT AT THE LOWER TEMP. BY CONTINUOUSLY ABSTRACTING THE HEAT FROM IT.

PRINCIPLE OF REFRIGERATIONPRINCIPLE OF REFRIGERATION

Heat Rejected Work Input

Heat abstracted

High Temperature Reservoir

Low Temperature Reservoir

R

TYPES OF REFRIGERATIONTYPES OF REFRIGERATION

NATURAL REFRIGERATION NATURAL REFRIGERATION THE COOLING EFFECT IS

PRODUCED BY EVAPORATION OF LIQUID OR MELTING OF SOLIDS

MECHANICAL REFRIGERATION MECHANICAL REFRIGERATION THE COOLING EFFECT IS

PRODUCED BY EXTERNAL SOURCE OF MECHANICAL ENERGY OR HEAT ENERGY.

IT HAS THREE TYPESIT HAS THREE TYPES

VAPOUR COMPRESSION VAPOUR COMPRESSION CYCLECYCLE

VAPOUR ABSORPTION VAPOUR ABSORPTION CYCLECYCLE

AIR REFRIGERATION CYCLEAIR REFRIGERATION CYCLE

VAPOUR COMPRESSION REFRIGERATIONVAPOUR COMPRESSION REFRIGERATION

Condenser

Evaporator

High Pressure Side

Low Pressure Side

CompressorExpansion Device

12

3

4

REFRIGERANTREFRIGERANT

PROPERTIES:-PROPERTIES:-

IT IS A HEAT CARRYING MEDIUM WHICH ABSORBS HEAT FROM SPACE WHICH IS TO BE COOLED AND REJECT IT TO THE ATMOSPHERE. e.g. NH3, R-11, R-12, R-22, R-134a, CO2, AIR etc.

HIGH LATENT HEAT OF EVAPORATION.

GOOD THERMAL CONDUCTIVITY.

NON-TOXIC, NON FLAMMABLE.

IT SHOULD BE ECONOMICAL.


Condenser

Evaporator

High Pressure Side

Low Pressure Side


12

3

4

Low pressure liquid refrigerant in evaporator absorbs heat and changes to vapour


The superheated vapour enters the compressor where its pressure is raised

Condenser

Evaporator

High Pressure Side

Low Pressure Side


12

3

4


Condenser

Evaporator

High Pressure Side

Low Pressure Side


12

3

4

The high pressure superheated gas is cooled in several stages in the condenser


Condenser

Evaporator

High Pressure Side

Low Pressure Side


12

3

4

Liquid passes through expansion device, which reduces its pressure and controls the flow into the evaporator

DOMESTIC REFRIGERATORDOMESTIC REFRIGERATOR

IT WORKS ON VAPOUR COMPRESSION CYCLE.IT WORKS ON VAPOUR COMPRESSION CYCLE.

FRONT SIDE FRONT SIDE

BACK SIDE BACK SIDE

P-h & T-s DIAGRAM OF VCR SYSTEMP-h & T-s DIAGRAM OF VCR SYSTEM

P

h

T

S

CONDENSATION

CO

MPR

ESSIO

NEVAPORATION

EX

PA

NS

ION

1

23

41

2

3

4

h2h1h2=h3

P2=p3

P1=p4

s3 s4 s1=s2

T2

T3

T1=T4

Pressure-Enthalpy (p-h) Diagram

Temperature- Entropy (T-s) diagram

UNIT OF REFRIGERATIONUNIT OF REFRIGERATION

TON OF REFRIGERATIONTON OF REFRIGERATION

IT IS DEFINED AS THE AMOUNT OF HEAT REQUIRED TO REMOVED IN IT IS DEFINED AS THE AMOUNT OF HEAT REQUIRED TO REMOVED IN ORDER TO FORM ONE TON OF ICE IN 24 HOUS FROM WATER AT ORDER TO FORM ONE TON OF ICE IN 24 HOUS FROM WATER AT TEMPERATURE 0TEMPERATURE 0°C.°C.

LATENT HEAT OF ICE IS 335 KJ/KGLATENT HEAT OF ICE IS 335 KJ/KGREFRIGERATION REQUIRED TO PRODUCE 1 TON (1000 KG) ICE IN 24 REFRIGERATION REQUIRED TO PRODUCE 1 TON (1000 KG) ICE IN 24 HRS.HRS.

= 335X900 KJ/HR= 335X900 KJ/HR 24 24

=210 KJ/MIN=210 KJ/MIN

=3.5 KW=3.5 KW

1 TON OF REFRIGERATION 1 TON OF REFRIGERATION =3.5 KW=3.5 KW

ASSESMENT OF REFRIGERATIONASSESMENT OF REFRIGERATION

CO-EFFICIENT OF PERFORMANCECO-EFFICIENT OF PERFORMANCE

COP = REFRIGERATING EFFECT IN KWCOP = REFRIGERATING EFFECT IN KW

WORK OF COMPRESSOR IN KW WORK OF COMPRESSOR IN KW

VAPOUR ABSORPTION REFRIGERATIONVAPOUR ABSORPTION REFRIGERATION

Condenser Generator

Evaporator

AbsorberCold Side

Hot Side

Low pressure, low temp vapour NH3 coming from Evaporator enters in absorber where it is absorbed by weak solution coming from generator.


Condenser Generator

Evaporator

AbsorberCold Side

Hot Side


Condenser Generator

Evaporator

AbsorberCold Side

Hot Side

Strong solution enters into generator, where it is heated and NH3 seperated from solution.


Condenser Generator

Evaporator

AbsorberCold Side

Hot Side

NH3 vapour coming from generator rejects the heat in condensor and transform into liquid state.


Condenser Generator

Evaporator

AbsorberCold Side

Hot Side

Liquid NH3 is throttled through expansion device and it enters into evaporator


Condenser Generator

Evaporator

AbsorberCold Side

Hot Side

NH3 evaporates by absorbing latent heat of evaporation to produce refrigerating effect.

AIR REFRIGERATIONAIR REFRIGERATION

AIR REFRIGERATION IS WIDELY USED IN AIR REFRIGERATION IS WIDELY USED IN AEROPLANESAEROPLANES

WHY REFRIGERATION IS REQUIRED IN AEROPLANES?WHY REFRIGERATION IS REQUIRED IN AEROPLANES?

AIR RAMMINGAIR RAMMING

SOLAR RADIATIONSOLAR RADIATION

CONTROLSCONTROLS

PASSENGERSPASSENGERS

AIR REFRIGERATION SYSTEMAIR REFRIGERATION SYSTEM

COMPRESSOR

RAM AIR IN

BYPASS RAM AIR

HE

FAN

EXPANDER

AIR TO CABIN

AIR EXIT

ADVANTAGES OF ADVANTAGES OF AIR REFRIGERATIONAIR REFRIGERATION

1. AIR IS CHEAP & EASILY AVAILABLE REFRIGERANT.

2. AIR IS NON TOXIC & NON FLAMMABLE.

3. COLD AIR CAN BE DIRECTLY SUPPLIED TO THE REFRIGERATED SPACE SO THERE IS NO NEED OF EVAPORATOR WHICH RESULTS IN LESS WEIGHT OF THE SYSTEM.

WHAT IS AIR CONDITIONING?WHAT IS AIR CONDITIONING?

The Air conditioning is defined as the The Air conditioning is defined as the simultaneous control of :- simultaneous control of :-

TemperatureTemperature HumidityHumidity Air movementAir movement Air cleanlinessAir cleanliness

Air Conditioning Air Conditioning

APPLICATIONS OF APPLICATIONS OF AIR CONDITIONING AIR CONDITIONING

FOR HUMAN COMFORTFOR HUMAN COMFORT

To provide cooling or heating and conditioning of air as per To provide cooling or heating and conditioning of air as per comfort of human being. This is known as comfort air comfort of human being. This is known as comfort air conditioning.conditioning.

Comfort air conditioning means conditioning of air in such Comfort air conditioning means conditioning of air in such a way that the human being can feel good.a way that the human being can feel good.The standards for comfort conditions are:The standards for comfort conditions are:

Temp. - 17Temp. - 17°C to °C to 2525°C°CHumidity - 30% to 70%Humidity - 30% to 70%Velocity of air – 0.1 m/s to 0.25 m/sVelocity of air – 0.1 m/s to 0.25 m/s


FOR HUMAN COMFORTFOR HUMAN COMFORT


FOR COMMERCIAL USEFOR COMMERCIAL USE

To provide cooling or heating and conditioning of air To provide cooling or heating and conditioning of air as per required in some engineering manufacturing as per required in some engineering manufacturing processing. This is known as industrial air conditioning.processing. This is known as industrial air conditioning.

HOW DOES A WINDOW A/C WORK?HOW DOES A WINDOW A/C WORK?

SPLIT AIR CONDITIONERSPLIT AIR CONDITIONER

THANKSTHANKS

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