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The Carnot cycle, which has a quantum equivalent, [11] is reversible so the four processes that comprise it, two isothermal and two isentropic, can also be reversed. When a Carnot cycle runs in reverse, it is called a reverse Carnot cycle. A refrigerator or heat pump that acts according to the reversed Carnot cycle is called a Carnot ...
A Carnot cycle is an ideal thermodynamic cycle proposed by French physicist Sadi Carnot in 1824 and expanded upon by others in the 1830s and 1840s. By Carnot's theorem, it provides an upper limit on the efficiency of any classical thermodynamic engine during the conversion of heat into work, or conversely, the efficiency of a refrigeration system in creating a temperature difference through ...
The operating principle of the refrigeration cycle was described mathematically by Sadi Carnot in 1824 as a heat engine. The most common types of refrigeration systems use the reverse-Rankine vapor-compression refrigeration cycle, although absorption heat pumps are used in a minority of applications. Cyclic refrigeration can be classified as:
In a reciprocating quantum heat engine the working medium is a quantum system such as spin systems [16] or an harmonic oscillator. [17] For maximum power the cycle time should be optimized. There are two basic timescales in the reciprocating refrigerator the cycle time τ cyc {\displaystyle \tau _{\text{cyc}}} and the internal timescale 2 π ...
The cycle is reversible, meaning that if supplied with mechanical power, it can function as a heat pump for heating or cooling, and even for cryogenic cooling. The cycle is defined as a closed regenerative cycle with a gaseous working fluid. "Closed cycle" means the working fluid is permanently contained within the thermodynamic system.
The Cromer cycle is primarily used in air conditioning and drying applications. The cold surface portion of the cycle is most often a result of a reversed Carnot or refrigeration cycle. For the Cromer cycle to operate, a desiccant must be exposed to two air streams, one with higher humidity from a cold surface, and one with lower humidity to ...
The most common refrigeration cycle is the vapor compression cycle, which models systems using refrigerants that change phase. The absorption refrigeration cycle is an alternative that absorbs the refrigerant in a liquid solution rather than evaporating it. Gas refrigeration cycles include the reversed Brayton cycle and the Hampson–Linde cycle.
The coefficient of performance, and the work required by a heat pump can be calculated easily by considering an ideal heat pump operating on the reversed Carnot cycle: If the low-temperature reservoir is at a temperature of 270 K (−3 °C) and the interior of the building is at 280 K (7 °C) the relevant coefficient of performance is 27.