Knowra Heat pump and refrigeration cycle Heat pump and refrigeration cycle A thermodynamic cycle that uses work to move heat from a colder region to a warmer one. Reversing its heat flows enables either refrigeration or space heating.
Vapor-compression refrigeration : A refrigeration cycle that circulates a vapor-compressible working fluid through a compressor, condenser, expansion device, and evaporator. This is the cycle’s most common practical form, used in refrigerators and many heat pumps.
First law of thermodynamics : The principle that energy is conserved, changing form or moving between systems rather than being created or destroyed. It accounts for heat delivered as the sum of extracted heat and compressor work.
Air-source heat pump : A heat pump that exchanges heat with outdoor air as its source or sink. It applies the cycle to building heating and cooling without a ground loop.
Absorption refrigerator : A refrigerator driven mainly by heat, using an absorbent and refrigerant pair instead of a mechanical vapor compressor. It produces refrigeration with a different cycle and energy input than the work-driven compression cycle.
Compressor : A machine that raises a gas’s pressure by supplying mechanical work. It raises refrigerant pressure and temperature, enabling heat rejection at the warm side.
Second law of thermodynamics : The principle that spontaneous processes increase total entropy and that heat does not flow from cold to hot without work. It explains why the cycle must consume work to pump heat uphill in temperature.
Ground-source heat pump : A heat pump that exchanges heat with the ground or groundwater through buried loops or wells. The relatively stable ground temperature can improve seasonal heating and cooling performance.
Transcritical carbon dioxide cycle : A refrigeration cycle using carbon dioxide that rejects heat above its critical pressure without condensing in a conventional condenser. It adapts the basic cycle for a natural refrigerant with distinctive high-pressure operation.
Condenser : A heat exchanger in which a vapor releases heat and becomes liquid. The cycle rejects heat to its surroundings as refrigerant condenses.
Enthalpy : A thermodynamic property equal to internal energy plus pressure times volume, useful for analyzing flowing fluids. Refrigerant enthalpy changes quantify heat absorbed, heat rejected, and work in cycle calculations.
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