Towards an integral decision-making process applied to the refrigerant selection in heat pumps

Abstract

In practice, there are methods such as EN 15450 designing a heat pump system consisting of a heat pump, auxiliary heater, and thermal energy storage. In heat pumps, the refrigerant has a significant impact on the overall efficiency and thus on its sustainability. However, refrigerant selection is not considered in standard design procedures. Moreover, the refrigerant selection is complex due to many selection criteria, boundary conditions, and stakeholder dependencies. Therefore, a guided procedure is promising to support the selection process. Applying prescriptive decision theory and the PROMETHEE method, a seven-phase selection process is presented, focusing on refrigerant selection for residential applications. Compared to standard selection processes, we integrate a stakeholder dependency into the evaluation to capture process-relevant boundary conditions. We carry out four phases of the decision process and present a reduced refrigerant list for residential heat pumps. Based on stakeholder-dependent and process-relevant boundary conditions, mainly hydrocarbons and their mixtures represent a sustainable selection. However, hydrocarbons are flammable and safety significantly impacts different stakeholders. Hence, a recommendation for further and especially safety measures, which should be proven in living labs, is deduced to increase the quality of the refrigerant selection towards sustainable heat pump systems.