Chapter 1 - Fundamentals

Abstract

Refrigeration is the science of moving heat from low temperature to high temperature. In addition to chilling and freezing applications, refrigeration technology is applied in air conditioning and heat pumps. This chapter describes the fundamentals of refrigeration. The minimum amount of work to drive a refrigerator can be defined in terms of the absolute temperature scale. Matter may have different forms of energy, potential, or kinetic, depending on pressure, position, and movement. Enthalpy is the sum of its internal energy and flow work. If a change of enthalpy can be sensed as a change of temperature, it is called sensible heat. This is expressed as specific heat capacity: the change in enthalpy per degree of temperature change, in kJ/(kg K). If there is no change of temperature but a change of state, it is called latent heat that is expressed as kJ/kg but it varies with the boiling temperature. Heat moves from a hot body to a colder one by conduction, convection, and radiation that is mainly by infrared waves, which are independent of contact or an intermediate fluid.