Nova Kool Manufacturing ULC

Basic Refrigeration Principles

Most users normally associate refrigeration with cold and cooling, yet the practice of refrigeration engineering deals almost entirely with the transfer of heat. This seeming paradox is one of the most fundamental concepts that must be grasped to understand the workings of a refrigeration system.

Cold is really only the absence of heat, just as darkness is the absence of light, and dryness is the absence of moisture.

Density & Specific Volume

Density: The density of a substance is defined as weight per unit volume, and in the United States is normally expressed in pounds per cubic foot. Since by definition density is directly related to specific volume, the density of a gas may vary greatly with changes in pressure and temperature, although it still remains a gas, invisible to the naked eye. Water vapor or steam at 50 psia pressure and 281 ° F. temperature is over 3 times as heavy as steam at 14.7 psia pressure and 212° F.

Specific Volume: Specific volume of a substance is defined as the number of cubic feet occupied by one pound, and in the case of liquids and gases, it varies with the temperature and the pressure to which the fluid is subjected. Following the perfect gas law, the volume of a gas varies with both temperature and pressure. The volume of a liquid varies with temperature, but within the limits of practical refrigeration practice, it may be regarded as incompressible.

Katey Werner