About Refrigeration VAR cycle VCR cycle application of Refrigeration

1. GANDHINAGAR INSTITUTE OF
TECHNOLOGY(012)
Active Learning Assignment on the topic of
“Refrigeration”
SUBJECT : ELEMENTS OF MECHANICAL
ENGINEERING(2110006)
BE
Prepared By: Pandya Yash D. (Enrollment no.)
2/27/2018 1

2. CONTAINS
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 Introduction
 How does it work ?
 Refrigerant
 Unit of Refrigeration
 Applications of Refrigeration
 Refrigeration system for Industrial
 Types Of Refrigeration

3. Introduction
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 The machine used for lowering or producing low temp.
in a body or a space, whose temp. is already below the
temp. of its surrounding, is called the refrigeration
system.
 Here the heat is being generally pumped from low level
to the higher one and is rejected at high temp.
 The term refrigeration may be defined as the process of
removing heat from a substance under controlled
conditions.
 It also includes the process of reducing heat &
maintaining the temp. of a body below the general
temp. of its surroundings.

4. How does it work?
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 Refrigeration and air conditioning is used to cool products or
a building environment.
R
Heat Rejected
High Temperature
Reservoir
Low Temperature
Reservoir
Heat Absorbed

5. How does it work?
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 Thermal energy moves from left to right through five loops
of heat transfer :-
1)
Indoor air
loop
2)
Chilled
water loop
3)
Refrigerant
loop
4)
Condenser
water loop
5)
Cooling
water loop

6. Refrigerant
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 The working substance used in refrigerating equipment is
known as Refrigerant.
 The refrigerant is a heat carrying medium which during their
cycle in a refrigeration system absorbs heat from a low temp.
system & delivers it to a higher temp. system.
 Refrigerant under goes various process of refrigeration cycles
which are used to produce refrigeration.
 Commonly used refrigerants are CFC, CHCIF2, NH3, CO2 and air.

7. Unit Of Refrigeration
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 The unit of refrigeration is ton of refrigeration.
 Simply ton denoted by TR.
 1 TON of refrigeration means amount of heat required to
remove from one short ton of water at 0°C to produce ice at
0°C in 24 hours.
 1 TR = kW
= 3.516 kW
334.9 ₓ 907.18
24 ₓ 3600
Lf of ice = 334.9 kJ /kg
1 ton = 907.18 kg

8. Refrigeration system for
Industrial
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 Small capacity modular units of direct
expansion type (50 Tons of Refrigeration)
 Centralized chilled water plants with chilled
water as a secondary coolant (50 – 250 TR)
 Brine plants with brines as lower
temperature, secondary coolant (>250 TR

9. Types Of Refrigeration
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 There are two types of refrigeration :-
1) Vapour Compression Refrigeration
(VCR): uses mechanical energy
2) Vapour Absorption Refrigeration
(VAR): uses thermal energy

10. 1) Vapour Compression
Refrigeration
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 This is the most important system from the point of
commercial & domestic utility & most practical form of
refrigeration.
 This system of refrigeration thus act as latent heat pump
since its pump its latent heat from the cold body or brine
& rejects it or deliver it to the external hot body or the
cooling medium.
 According to the law of thermodynamics , this can be
done only on the expenditure of energy which is
supplied to the system in the form of electrical energy
driving the compressor.
 The vapour compression cycle is used in most of the
modern refrigeration systems in large industrial plants.

11. VCR
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 The vapour in this cycle is circulated through the various
components of the system, where it undergoes a
number of changes in its state or condition
 Each cycle of operation consists of the four fundamental
changes of state or processes:-
 Expansion
 Vaporisation
 Compression
 Condensation

12. VCR cycle
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Condenser
High
Pressure
Side
Expansion
Device
3
4
2 Low
Pressure
Side
1
Evaporator
Compressor

13. 2) Vapour Absorption
Refrigeration
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There are two widely used absorbent – refrigeration pairs for vapour
absorptionsystem:
1) NH3 – H2O system :
in which NH3 is refrigerant and H2O is absorbent.
2) H2O – LiBr system :
in which H2O is refrigerant and LiBr is absorbent.
NH3 vapour enters the absorber. In absorber it is absorbed by weak
solution coming from generator through throttle valve. Due to absorption
of NH3 vapour solution becomes strong. Heat of absorption is released
and it is to be rejected to cooling medium. This strong solution is pumped
in to generator at point. In generator heat is supplied from external
source and NH3 vapour is generated.

14. VAR cycle
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Condenser
Generator
Evaporator
AbsorberCold
Side
Hot
Side

15. THANK YOU
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