Carnot engine refrigerator

Figure 6.1. Scheme of a Carnot engine as a) a heat engine and b) as a refrigerator or heat pump. 

The ideal work of the process is that of a Carnot engine operating between the temperature of the refrigerated space and the temperature of the surroundings. 

Let engine E drive the Carnot engine backward as a Carnot refrigerator, as shown schematically in Fig. 5.1. For the engine/refrigerator combination, the net heat extracted from the cold reservoir is... 

A Carnot engine is coupled to a Carnot refrigerator so that all of tlie work produced by the engine is used by the refrigerator in extraction of heat from a heat reservoir at... 

Suppose we run the Carnot engine in reverse, as a refrigerator, but instead of having the interior of the refrigerator serve as the cold reservoir we use the outdoors as the cold reservoir and the interior of the house as the hot reservoir. Then the refrigerator pumps heat, Q2, from outdoors and rejects heat, — 6u the house. The coefficient of performance of the heat pump, is the amount of heat pumped into the high temperature... 

The Carnot cycle can be operated in the reverse direction, and then the signs are reversed for the work and heat in each step. This means that net work is done on the gas in one cycle, and heat is released into the higher-temperature bath (step 1) and absorbed from the lower-temperature bath (step 3). In this manner, the Carnot engine operates as a heat pump or refrigerator. 

Figure 2.18 Alternative representation for the Carnot cycle, (a) Carnot engine (b) Carnot refrigerator.

Fig. 1. Schematic representation of (a) Carnot heat engine and (b) Carnot refrigerator used as a heat pump.

See also Carnot, Nicolas Leonard Sadi Climatic Effects Engines Matter and Energy Nuclear Energy Nuclear Fission Refrigerators and Freezers Thermal Energy. 

It is an immediate consequence of Carnot s theorem that the ratio of the quantities of heat absorbed and rejected by a perfectly reversible engine working in a complete cycle, depends only on the temperatures of the bodies which serve as source and refrigerator. 

A distinction must be drawn between available energy unnecessarily dissiputed into unavailable energy, by reason of some irreversibility inherent to some part of the process, and the necessary balance of unavailable energy left in the refrigerator of a Carnot s engine which is working in a perfectly reversible manner. 

If the Carnot cycle for a heat engine is carried out in the reverse direction, the result will be either a Carnot heat pump or a Carnot refrigerator. Such a cycle is shown in Fig. 1.5. Using the same graphical explanation that was used in the Carnot heat engine, the heat added from the low-temperature reservoir at Tl is area 1-4-5-6-1 g4i is the amount of heat added to the Carnot cycle from a low-temperature thermal reservoir. 

The Carnot cycle is a reversible cycle. Reversing the cycle will also reverse the directions of heat and work interactions. The reversed Carnot heat engine cycles are Carnot refrigeration and heat pump cycles. Therefore, a reversed Carnot vapor heat engine is either a Carnot vapor refrigerator or a Carnot vapor heat pump, depending on the function of the cycle. 

Chen, L. and Wu, C., Effect of heat transfer law on the performance of generalized irreversible Carnot refrigerator. Journal of Engineering Thermophysics, 20(2), 10-13, 1999. 

Just as the Carnot cycle C of Fig. 4.3 can be claimed to be the most efficient possible heat engine ( reai < fcamot = 1 — c/ h )> so too can the reverse Carnot cycle C be claimed to be the most efficient possible refrigerator ... 

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