Exemples de développements de pompe à chaleur aux fluides naturels : cas du propane et du CO2.

The evolution of the directives on the use of refrigerants, classified as greenhouse-gases, stimulates research on suitable replacement solutions. In the systems operating thanks to a mechanical vapour-compression cycle, technical solutions have started to emerge, based on the use of so-called natural refrigerants, such as propane and carbon dioxide. Propane has interesting transfer properties as compared to presently-used refrigerants. Research on increased system compactness with propane is a major issue in the development. Carbon dioxide has the particularity of being used in a transcritical cycle, in which the compressor discharge pressure is higher than the critical pressure (73.8 bars). The authors present these various elements, with the experimental results obtained on two vapour-compression system prototypes. The characteristics of the heat exchangers used and the measured thermal performances will be dealt with in particular.