Refrigeration cycles in commercial and Industrial Units

A typical commercial mechanical refrigeration system is illustrated. This system is made possible by the proper use of temperature, pressure and latent heat of vaporization. Instead of ammonia, other substances having certain advantages are widely used. In the system swown, water is circulated in the condenser. The water removes heat from the hot, compressed refrigerant to condense it. Thus, the water carries away the heat that is picked up by the evaporator as the refrigerant boils. It can now again carry out its function of picking up heat.
Note that at the top of the drawing an expansion (metering device) valve is placed in the line between the condenser and the evaporator. This expansion valve provides a restrction (reduced sized opening) so that there is a steady flow of refrigerant.
The valve also maintains the diffrence of pressure required to change the state of the efrigerant, that is, fromm a liquid to a gas.
The accompanying schematic diagram shows a refrigeration cycle simplified terms. Since this is a basic cycle, the following facts must be known:
1. Heat is picked up by the boiling refrigerant regardless of the shape of the
evaporator.
2. Heat which is rejected at the condenser may be carried away by air, water, the
evaporation of water, or other means.
3. The function of a metering device or expansion valve is to permit the compressor
to maintain a pressure difference.
4. The heart of the system provides the energy for its operation whether it be by
mechanical, heat, or other energy.
The diffrent components (main parts) which are identified and described in detail in succeeding units are related to this basic refrigeration cycle.