What is a refrigerator used in a heat engine?

To obtain useful work, it is necessary that the work of the external force be less than the work done during the expansion of the gas. This is possible if the pressure (respectively, and the temperature) during the expansion of the gas was greater than during the compression. Therefore, before compression or during compression, the gas must be cooled, that is, brought into contact with a body, the temperature of which is T2 <T1 This body (it is called a refrigerator) is transferred from the working body part of the internal energy.

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