Exergy analysis of heat pumps for simultaneous heating and cooling

This article presents the evolution of a concept of air-source heat pump for simultaneous heating and cooling (HPS). A heat pump can simultaneously produce heating and cooling energies for collective residential buildings, hotels or highly-glazed office buildings. The heat pump prototypes operate under three main modes. (1) The heating mode produces hot water using heat available in the ambient air. (2) The cooling mode produces cold water and rejects heat to the ambient air. (3) The simultaneous mode produces hot water thanks to heat taken from the cold water, therefore becoming colder. During the simultaneous mode, two thermal energy amounts, for cooling and heating, are produced simultaneously. Therefore, it is interesting for the user that the heat pump operates in the simultaneous mode as much as possible. A winter operating sequence involving a heat exchanger for refrigerant subcooling enhances the performance of the machine. Two prototypes working with R407C and R290 (propane) were built consecutively and tested following European Standard EN 14,511 in a climatic chamber. The experimental results show that the second prototype has a higher performance than the first one regarding exergy aspects thanks to not only the refrigerant choice but also to a better design of components.