The document discusses the history and basic principles of refrigeration. It describes how William Cullen conducted early experiments in artificial refrigeration and how Oliver Evans designed the first refrigeration machine. The basic principle is explained as passing a colder liquid around an object to continuously remove heat from it. The key components of a refrigerator - compressor, condenser, evaporator, and throttling device - are outlined. The document also provides details on how each component functions within the refrigeration cycle and explains the concept of refrigerants. Common refrigerants like R12, R290, R134a, and R600a are mentioned.

1. Mahakal Institute of Tech. & Science,
Ujjain
Submitted By: Prakhar Pandey

2. Contents
o Introduction
o History
o The Basic Principle
o Components of Refrigerator & Working
o Concept of Refrigerant
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3. Introduction
What is a Refrigerator
The mechanism used for removing heat from a
substance under controlled conditions.
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4. History
o William Cullen, the first to conduct experiments into artificial
refrigeration.
o Oliver Evans, designed the first refrigeration machine for
practical purpose.
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5. The Basic Principle
Basic principle of refrigeration is simple-
Just pass a colder liquid continuously around the object which is
to be cooled. This will take heat out from the object.
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6. Components of Refrigerator
It has got 4 main components;
o Compressor
o Condenser
o Evaporator and
o Throttling Device.
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7. Throttling Device
o Throttling device is an obstruction to the flow.
o It is responsible for the production of cold liquid.
o It causes the pressure and temperature drop in high pressure
liquid.
Length = 2m
Diameter = 0.6mm
(www.learningengineering.com)
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8. Evaporator - Heat Absorption Process
o The Evaporator is a heat exchanger
required to carry the cold refrigerant
over the body.
o Here, the refrigerant further evaporates
and transforms into pure vapor.
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9. Compressor
o Usually hermetically sealed reciprocating type with proper
sealing is used.
o Compressor will raise the pressure back to its initial value.
o Now the refrigerant is high pressure vapor.
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10. Condenser
o This heat exchanger is fitted
outside refrigerator.
o Here, vapor will get condensed to
liquid and temperature will come
down to normal level.
o Now the refrigerant is high
pressure liquid.
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11. Refrigerant concept
o Refrigerant = R
o Notations = CmHnFpClq
o In which, (n + p + q) = 2m+2 (for saturated hydrocarbon)
(n + p + q) = 2m (for unsaturated hydrocarbon)
R(m−1)(n+1)(p)
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12. Cntd.
Presently Working
substance is R12, R12
is CFC (chloro-floro
carbon).
B’use of the ozone
layer depletion
problem, alternatives
such as following are
also used in place of
R12-
• R290, viz., Propane C3H8)
• R134a viz., Tetra-
fluoroethene (C2H2F4)
• R600a, viz., Isobutane
(C4H10)
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