ABSTRACT
Heat pumps capture heat energy from low grade heat sources such as ambient air, ground, and waste heat streams and upgrade to a higher temperature level for useful applications. This entry includes a brief history, fundamentals, classifications, applications and performance parameters of heat pumps. Working principles of the magnetic heat pump, the thermoelectric heat pump, the absorption heat pump, the adsorption heat pump, the gas compression heat pump, and the vapor compression heat pump are explained. Performance parameters of the heat pump systems (coefficient of performance, energy efficiency ratio, primary energy ratio, and ambient energy fraction) are presented. The short‐term and long‐term greenhouse gas saving potentials for the use of heat pumps are discussed.
