How Does a Heat Pump Work?
Heat pumps are devices that work on principle of refrigeration invented by Rankine early in the 20th century. They are refrigerators that have been optimized, not for cooling the insides of a cabinet but to provide an external heat source, hence the name Heat Pumps. Heat Pumps are used in various applications. The Main application of a Heat Pump is to provide hot water for domestic and commercial use. The hot water produce by the Heat Pump is used in laundrettes to provide the hot water for the washing cycle. Heat pumps can also be employed as the heat source in large commercial Tumble Dryers. The typical temperature that a Heat Pump produces is between 60-70 degrees Centigrade, 130-150 degrees Fahrenheit. Heat Pumps are also used in domestic and commercial central heating systems often replacing a fossil fuel powered boiler. Heat Pumps are also used as reverse cycle air conditioners that provide cooling in the summer months and heating during the winter months. There are four main types of Heat Pump on the market today. These are the geothermal type, Air to water type, Water to water type and finally the Reverse cycle heat pump used in air conditioning.
How Does a Heat Pumps work?
A basic Heat Pump of all types consists of an evaporator, a heat exchanger, condenser, compressor copper pipes and a control circuit. The geothermal heat pump has a circulating pump and the reverse cycle air to air heat pump contains a reversing valve. All the types of Heat Pump use Freon gas as the heat transfer medium. Stating at the compressor the unit compresses the heat saturated gas from the evaporator into a very of liquid. This liquid exits the compressor at between 70-90 degrees Centigrade, 160-180 degrees Fahrenheit This hot liquid is then passed through the primary heat exchanger were it gives up most but not all its heat. The hot gas is then passed through a smaller secondary heat exchanger where the gas is cooled usually by a fan blowing across the condenser coil into a cool liquid. This cool liquid is then passed to the capillary tube where the cool liquid is compressed further into a higher pressure. This high pressure cold gas is forced through the capillary tube and into the evaporator. On entering the evaporator it uses heat to expand rapidly into a heat saturated gas which is then returned to the compressor where the heat pump cycle begins again.