Refrigeration Concept :


                  In thermodynamics, Refrigeration is one of the most important concept, which has very wide applications in Human's life. Air coolers, Fridges, Air Condition etc are some of the highly famylier applications.

                  The American Society of Refrigeration engineers define that, Refrigeration is the science of Providing and maintaining the temperature below surrounding temperature. In this definition, the words which are to be focused are lower temperature and surrounding temperature. After studying this carefully we can say, for some cases Refrigeration is a relative concept. Lets Assume some examples :

  1. We have a fridge/ Refrigerator at home. It works on electricity. Definitely its common that temperature exchange to surroundings is not allowed. In this case System is the cold storage where temperature is maintained below a limit. But considering from other side the refrigerator forcefully transfers that heat to surroundings / Outside. If outside atmosphere is considered to be SYSTEM then the system is getting HEATED and surroundings (here cold storage) is getting freezed.
  2. On other side if we consider heater, In winter it transfers heat from Cold nature to hot room forcefully. Here we generally consider Room as System and Outside as Surrounding, for this case it is a heating process but if outside is considered as system it is a Refrigeration process. 
                    So any heat transfer process may be heating or cooling process. It may depend upon consideration of system and surrounding. From this analysis definitely Refrigeration process is said to be relative.

VCR (Vapour Compression Refrigeration) System :

VCR system consists of the following components:
  • Compressor 
  • Condenser 
  • thermostatic Expansion valve
  • Evaporator
Also working fluids / Refrigerants like Carbon Dioxide, Ammonia, Sulphur Dioxide, R12, R22 are used. 
As shown below the arrangement of the components of VCR system works:


                     The refrigerant vapour is sucked in Compressor and it is compressed. Due to compression its temperature and pressure are increased. This compressed vapour then goes to condenser. This vapour is condensed and temperature is lowered. after condensation this high pressure low temperature fluid goes to condenser and there it is throttled ie expansion takes place. This low temp low pressure fluid goes to Evaporator to form a low pressure vapour. This low pressure low temperature fluid passes through capillary tubes in evaporator. As shown in figure the fan blows the warm  air from system to evaporator and that air cools and goes to surroundings, but due to this heat transfer temperature of vapour increases and again it goes to compressor and this process continues.Ph diagram is shown below.



                     For this case also the concept of relativity is applied in vaporiser. when the warm air from system is exhausted on tubes containing refrigerant liquid. There the warm air is cooled but the refrigerant is heated up, as warm air is a medium of transfer of heat from system to surroundings, temperature of system is lowered and hence Refrigeration takes place. This Refrigeration system is known as VCR (vapour compression Refrigeration) System. 

(The Idea of Relativity is just an idea presented by author to understand Heat Transfer and analyse it.)



Published by :

Shreyas S Chaudhari.