The process of refrigeration consists of the removal of heat from a body that is colder than its surroundings.
Refrigeration cycle:
Process of removing heat from a body.
Refrigeration circuit:
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Physical components involved in the cycle, evaporator, compressor, condenser. Throttling/expansion valve or capillary tube, blower coil.
Refrigeration system:
A refrigeration/Refrigerated system is an apparatus or Combination of mechanical equipments in which a refrigerant is circulated for cooling or extracting heat from space.
Refrigeration units/Refrigerators:
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(i) Domestic refrigeration units:
Small sized air conditioner.
(ii) Commercial refrigeration:
Medium sized, Transport Refrigeration, ice plant.
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(iii) Industrial refrigeration:
Large sized cold storage. Treatment of metals.
(iv) Self contained refrigeration unit:
All the components are assembled in one decorative enclosure-Room air conditioner.
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(v) Remote Refrigeration unit:
Refrigeration unit & heating unit are separated from each other, central air conditioning unit.
Applications of Refrigeration:
Following are applications:
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(a) Food storage
(b) Food Processing
(c) Chemical Industries
(d) Food transportation
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(e) Air conditioning
(f) Oil refineries
(g) Manufacturing and treatment of metals
(h) Medical applications
(i) Creation of artificial atmosphere.
Methods for Providing Refrigeration Effects:
(i) Ice refrigeration:
Ice is put around the object or liquid which is to be cooled, separation is by wood or steel. In this heat is taken from object and ice melts & converted in to water.
(ii) Evaporative refrigeration:
Volatile liquid absorbs its latent heat of Vaporization from the space or object which is to be cooled & gives this heat to the coolant in the condenser and again becomes liquid.
(iii) Dry refrigeration
(iv) Gas/Air expansion refrigeration:
First-compress a gas adiabatically and then cool this high pressure gas keeping pressure constant. Then cool this high pressure low initial temperature gas to a atmospheric pressure, it is found that temperature of the gas will be less than 0″C.
(v) Gas Throttling refrigeration
(vi) Steam jet refrigeration
(vii) Liquid gas refrigeration
(viii) Vapour comperssion refrigeration
(ix) Vapour absorption refrigeration
(x) Thermoelectric refrigeration.
(xi) By chemical means
(xii) By means of heat pump cascade refrigeration system.
Laws of Refrigeration:
(i) Fluid absorbs heat while changing from a liquid to a Vapour state and vice versa-condenser & evaporator.
(ii) The temperature at which a changing state occurs is constant if pressure remains constant, condenser & evaporator.
(iii) First law of thermodynamics.
(iv) Second law of Thermodynamics.
Evaporator & condenser material, have high heat conductivity.
Refrigerator:
A m/c producing cold or a heat pump and to remove heat from the cold body to produce low temperature for useful purpose.
Refrigeration effect:
The rate of heat absorbed from the body or space to be cooled is the refrigerating effect.