What is Refrigeration? In general, refrigeration is defined as any process of “HEAT REMOVAL.” More specifically, refrigeration is defined as the branch of science that deals with the process of reducing and maintaining the temperature of a space or material below the temperature of the surroundings. To accomplish this, heat must be removed from the body being refrigerated and transferred to another body whose temperature is below that of the refrigerated body. Since heat will always move from a region of high temperature to a region of lower temperature, there is a continuous flow of heat into the refrigerated region from the warmer surroundings. To limit the flow of heat into the refrigerated region to some practical minimum, it is usually necessary to isolate the region from its surroundings with a good heat insulating material. Definition: – Refrigeration load is the rate at which heat must be removed from the refrigerated space or material in order to produce or maintain the desired temperature conditions. The Total Refrigeration Load on the refrigeration equipment is found by adding the heat gained from the following sources: .
The heat transmitted through the insulated walls. The heat that must be removed from the warm air that enters the space through opening and closing doors… The heat that must be removed from the refrigerated product to reduce the temperature of the product to the storage temperature… The heat given off by people working in the refrigerated space, by motors, lights and other heat producing equipment operating in the space. Definition: In any refrigerating process, the substance employed as the heat absorber (or cooling agent) is called the Refrigerant. Sensible and Latent Cooling Processes.
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All cooling processes may be classified as either sensible or latent according to the effect the absorbed heat has upon the refrigerant. When the absorbed heat causes an increase in temperature of the refrigerant, the cooling process is said to be sensible. When the absorbed heat causes a change in the physical state of the refrigerant [changing from a solid to a liquid (melting) or changing from a liquid to a gas (vapour ising) ], the cooling effect is said to be latent. With either process, if the refrigerating effect is to be continuous, the temperature of the refrigerant must be kept below that of the space or material being refrigerated.
It is possible and practical to achieve continuous refrigeration with a sensible cooling process provided that the refrigerant is continuously chilled and re-circulated through the refrigerated space. Latent cooling may be accomplished with either solid or liquid refrigerants. The solid refrigerants most frequently employed are: – ICE & SOLID CARBON DIOXIDE. ICE.