Refrigerant Selection for District Heating’s Large-scale Heat Pumps

Abstract: The global demand for heat as the primary source of final energy underscores the urgency of decarbonizing the heating sector to foster sustainability. Heat pumps are crucial in achieving sustainability, particularly in district heating applications, offering efficient centralized heating solutions. However, certain refrigerants used in heat pumps have environmental implications, prompting the European Union to introduce the F-Gas Regulation and PFAS Ban proposal to phase out harmful options. This study focuses on performance analyses of natural and synthetic refrigerant options applicable to heat pump systems with a heating capacity of 10 MW and above in district heating applications. Comparative evaluations were conducted under five distinct boundary conditions, using R134a as the current refrigerant. Moreover, to understand performance variations caused by seasonal temperature changes, additional general boundary conditions were introduced for further comparison. The research demonstrates that R717(Ammonia) performs best among the tested refrigerants, followed by R600a and R152a, with commendable results. However, performance alone is insufficient for refrigerant selection. Safety analysis revealed that despite its high performance, ammonia may not be a suitable choice due to its toxic nature. Thus, when considering performance, technological compatibility, and safety aspects, R152 or R600a refrigerants emerge as more appropriate options for these applications. The study highlights the importance of identifying environmentally friendly and efficient refrigerants for heat pump systems in district heating applications. By considering various performance scenarios and safety considerations, decision-makers can make informed choices to decarbonize the heating sector effectively, contributing to a more sustainable and eco-friendly world.