CHAPTER ONE
INTRODUCTION
Refrigeration is defined as a process of removing heat from the evaporator in other to make it cooler. More so, it is the branch of science, which deals with the process of reducing and maintaining the temperature of the surroundings.
Generally, however, for a space to be cooler, it must loose heat to another substance. Also for a space or a material to get hotter, it must absorb heat from another substance, thus, heat is the characteristic agent of heating and cooling.
Consequently, for heat to flow there must be a medium or mode for the transmission. This implies from high temperature region to low temperature region.
In refrigeration process, there is always a body employed as the heat absorber or the cooling agent known as refrigerant.
The refrigerant circulates round the evaporating and condensing region. In other to maintain a constant refrigeration process, it does its work by evaporating and condensing.
When it loses the absorbed heat and return to its original liquid or solid state, as the case may be, classified as sensible heat or LATENT HEAT depending on the physical effect on the refrigerants.
Generally, when a mass body absorbs heat, the following physical change takes place.
(1) The mass expand or increase in physical dimensions (as the molecules resonate willing a wider range).
(2) The temperature increase (as molecules gain more internal kinetic energy).
(3) There is a change in phase (as the mass changes from solid to liquid and consequently to gas and vice versa).
1.2 THE REFRIGERATION
Refrigeration is an electro-mechanical appliance, which is used in maintaining the temperature of a substance as require of the user. Or it is electro mechanical appliance used in carrying on artificial cooling. It operate the principle’s of reversed cannot cycle.
In other words, heat is absorbed from a low temperature region and reject to a high temperature region. The temperature at which heat is absorbed is kept at constant.
The energy for the pumping of the refrigerant round the refrigeration cycle comes from the compressor (heat of the refrigerant) it takes use of both mechanical and electrical components.
The tongue for driving the crankshaft and consequently the piston is produced by an electric motor (it makes use of the magnetic effect of the current) similarly, the pumping effect of the piston arêtes the high pressure which induces to the refrigeration.
This thus set in motion to the refrigerants which after some physical metamorphosis returns to the former staff –ready for another cycle.
In the refrigerator, the condenser performs a function similar to that of the radiator in an automobile; it is the cooling coil for the hot refrigerant gas. In the condenser, the refrigerant is condensed and expelled to the surrounding atmosphere. The metering device expanding the length of the gas and inside diameter to meter., the exact amount of liquid refrigerant flow requires for each unit, the evaporator consist of convolutions of a copper tubing which is where the actual cooling section of the refrigerator take place.
However, a lot of insulating is done o isolate the refrigeration space from the surrounding environment and it effect. This is achieved by the following measure.