Fabrication On Domestic Refrigerator

2.5    THE VAPOUR COMPRESSION REFRIGERATOR SYSTEM
Vapour compression refrigeration system is one of the many refrigeration cycles available for use. It has been and is the most widely use for chilled or frozen storage of food and meats, refrigerated, trucks and rail road ears, host of other commercial and industrial services.(Robert T, Belmar (2011): Modern Engineering thermodynamic”),
The system consists of the following parts.
i.    The evaporatror
ii.    The compressor
iii.    The condenser
iv.    The expansion valve
Process 1-2: The refrigerant leaves the evaporator as a gas at low temperature, it is compressed in the compressor to a high temperature and pressure. Process 2-3: The refrigerant leaves the compressor out high temperature and pressure in gaseous state. Heat of evaporation and compression is removed from the refrigerant in the condenser. The refrigerant flow through one circuit in the condenser not a lever temperature. As a result of this, the refrigerant condensed to liquid. But in the case of small size refrigerator, heat of compression and evaporation is conducted to the atmosphere.
Process 3-4: The refrigerant is in the liquid state at a relatively high temperature and pressure; it flows through the throttle valve or control device (expansion valve). On passing through the restriction, the refrigerant losses it pressure becomes low arid a little portion of the refrigerant is evaporated (expansion).
Process 4-1: Hence the refrigerant flows through the evaporator the substance to be cooled is at a higher temperature.
Weak NH3 solution (aqua ammonia) entering the absorb becomes strong solution after absorbing NH3 vapour and then it is pumped to the generator through the heat exchanger. The pump increases the pressure the strong solution to generator pressure. The solution in the generator becornes over as NH3 vapour comes out of it. The pressure of the liquid is reduced to the absorber pressure by the throttle valve.
This system can through provide refrigeration, yet its operation efficiency is very low. This system makes of the ability of another substance usually liquid. The absorbent hasthe ability to absorb large titles. Colin,(2005).
The following are merits and demerit of vapour absorption refrigeration system.
•    The energy supplied to the generator is informed of heat which can form kerosene, gas steam or hot water. Hence it is good in remote area where there is no electricity.
•    The system give quit manning with no vibration source heat rather than the mechanical power energy input to the system.
•    The system requires little maintenance one to fewer moving parts.
•    It is preferable option in industrial application where the heat that could otherwise he wasted serve as a heat source of absorption machine.
DEMERIT
•    The system is heavier than the compression refrigeration system and hence it is more expensive to produce.
•    The coefficient of performance of the system is lower than that of a vapour compression system operating under the same pressure limit.
Therefore heat is transferred from it to the refrigeration byconventional method of heat transfer. This, producing cooling ii red to preserve the food. The refrigerant vaporize because of the heat received from the substance to be cooled through the evaporator, it completely vaporized. The refrigerant has aimed to its initial stages andis now ready t o repeat the cycle Cohn (2005)
2.6     COMPONENT PARTS OF REFRIGERATION
Compressor: This is a mechanical device which draws in refrigerant gas and is at a higher pressure to the condenser. It is normally by an electric motor. Compressors are of various rating.
Condenser: The condenser is an apparatus which extract sensible and latest heat from its surroundings by evaporation of the liquid refrigerant metered into the liquid is thus transfer in to gas.
Liquid Receiver:It is a container which is situated lamed latch below the condenser to collect the liquefied refrigerant.
Suction Line: This is a pipe that delivers a fluid to the suctionor side of a pump or compressor. It connects the evaporator inlet and the compressor inlet. Low pressure refrigerator vapour is drawn from the evaporator to the compressor through the line.
Discharge Line: It is the line in which the refrigerant passes through after brings discharged by the compressor the substance to b\e cooled through the evaporator, it completely vaporized.