heat pump
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CG: n

CT: A heat pump is an electrical device that extracts heat from one place and transfers it to another. The heat pump is not a new technology; it has been used in Canada and around the world for decades. Refrigerators and air conditioners are both common examples of this technology.

S: NRC – http://www.nrcan.gc.ca/energy/publications/efficiency/heating-heat-pump/6827 (last access 9 December 2014).

N: 1. heat (n): Old English hætu, hæto “heat, warmth; fervor ardor,” from Proto-Germanic *haita– “heat” (cognates: Old Saxon hittia, Old Norse hiti, Old Frisian hete, German hitze “heat,” Gothic heito “fever”), from PIE *kaid-, from root *kai– “heat.” The same root is the source of Old English hat “hot” and hæða “hot weather”. Heat wave “period of excessive hot weather” first attested 1890; earlier in reference to solar cycles.
pump (n): “apparatus for forcing liquid or air,” early 15c., of uncertain origin, possibly from Middle Dutch pompe “water conduit, pipe,” or Middle Low German pumpe “pump” (Modern German Pumpe), both from some North Sea sailors’ word, possibly of imitative origin.
2. A heat pump is a device which applies external work to extract an amount of heat QC from a cold reservoir and delivers heat QH to a hot reservoir.
3. A heat pump is subject to the same limitations from the second law of thermodynamics as any other heat engine and therefore a maximum efficiency can be calculated from the Carnot cycle.
4. Heat Pumps are usually characterized by a coefficient of performance which is the number of units of energy delivered to the hot reservoir per unit of work input.
5. The most common type of heat pump is the air-source heat pump, which transfers heat between your house and the outside air.

S: 1. OED – http://www.etymonline.com/index.php?allowed_in_frame=0&search=heat&searchmode=none (last access: 9 December 2014). 2, 3 & 4. HPHYSICS – http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/heatpump.html (last access: 9 December 2014). 5. ED – http://energy.gov/energysaver/articles/heat-pump-systems (last access: 9 December 2014).

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CR: geothermal energy