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Thermodynamic heat pump cycles or refrigeration cycles are the conceptual and mathematical models for heat pump, air conditioning and refrigeration systems. [1] A heat pump is a mechanical system that transmits heat from one location (the "source") at a certain temperature to another location (the "sink" or "heat sink") at a higher temperature. [2]
This reduces the amount of the heat required to raise the temperature of the subcooled liquid of the working fluid to the saturation temperature corresponding to the pressure in the Rankinecycle's evaporator. So most of the heat is added at the maximum cycle temperature, and the Rankine cycle can approach more closely the Carnot cycle.
In winter a heat pump can move heat from the cool outdoors to warm a house; the pump may also be designed to move heat from the house to the warmer outdoors in summer. As they transfer heat rather than generating heat, they are more energy-efficient than heating by gas boiler. [2] A gaseous refrigerant is compressed so its pressure and ...
The maximum theoretical efficiency is ... (or Fluidyne heat pump), ... Increasing the temperature differential and/or pressure allows Stirling engines to produce more ...
A reversible heat engine with a low efficiency delivers more heat (energy) to the hot reservoir for a given amount of work (energy) to this engine when it is being driven as a heat pump. All these mean that heat can transfer from cold to hot places without external work, and such a heat transfer is impossible by the second law of thermodynamics.
The refrigerant is compressed by the compressor to a high-pressure and high-temperature gaseous state. The high-pressure and high-temperature gas then enters the condenser. The condenser cools the high-pressure and high-temperature gas allowing it to condense to a high-pressure liquid by transferring heat to a lower temperature medium, usually ...
In the heat engine model with two thermal reservoirs (hot and cold reservoirs), the limit of the efficiency of any heat engine =, where and are work done by the heat engine and heat transferred from the hot thermal reservoir to the engine, respectively, can be derived by the first law of thermodynamics (i.e., the law of conservation of energy ...
A low temperature difference (LTD, or Low Delta T (LDT)) Stirling engine will run on any low-temperature differential, for example, the difference between the palm of a hand and room temperature, or room temperature and an ice cube. A record of only 0.5 °C temperature differential was achieved in 1990. [44]