1. Thermodynamic cycles and their implementation

1.1 Thermodynamics reminder

The aim of cryorefrigerators is to remove a quantity of heat Q _f at a cold temperature T _f . This operation requires the input of energy, generally in the form of work W, and the release of a quantity of heat Q _c at the warm temperature T _c . These different quantities are shown in figure 1 . All the chillers described here are based on fluid cycles, most of which are closed.