ABSTRACT
A heat pump is mainly a refrigeration system similar to that used in a domestic refrigerator, but produces a heating effect rather than a cooling one. The cycle consists of a condenser that gives off heat, an evaporator that takes in heat, a compressor and an expansion valve. The components are connected by tubes in which a refrigerant circulates. The compressor is the only component that uses power. The attraction of heat pumps is that fi rst they are effi cient in terms of energy generation (typically for 1 kW of electricity consumed a pump gives off/ removes some 2.5 kW of heat, and second they can be used for both heating and cooling. They can take low-grade heat from any source (air, water, earth) and can be used to produce either heating or cooling effects.
