Performance and safety analysis of charge reduced brine to water heat pumps using R290

The European implementation of the Montreal protocol, the F-gas regulation, restricts the use of refrigerants with high Global Warming Potential (GWP). Thus, low-GWP refrigerants, in particular propane (R290), are be-coming the standard in the strongly growing heat pump market. Current production capabilities and safety solu-tions need to evolve to support the predicted growth. Within this contribution the results of the research project LC150 ("Low Charge 150g") are shown. The focus is on the reduction of charge needed in heat pumps, favorably below 150g Propane, and therefore reducing safety hazards. As part of this project at Fraunhofer ISE many different components were combined and experimentally evalu-ated regarding charge efficiency and thermal performance. Conclusions and correlations will be described based on ErP standards, total charge, COP, heating capacity and more. To support this analysis individual components in refrigerant circuits were replaced. Thus, a quantification of charge impact of a single component within one refrigerant circuit is possible. All measurements are done with compact plate-to-plate refrigerant circuits. The heating capacity range is be-tween 2 kW and 12 kW. The current best solution achieves a specific heating capacity <10 g/kW (g charge/ kW heating capacity) with a SCOP (ErP) >4.3. Additionally an easy-to-apply concept of the heat pump module will be presented, taking manufacturing and safety aspects into account. In this contribution part of the results will be shown and discussed regarding charge efficiency and thermal efficiency of individual components, as well as the safety concepts supporting the charge reduced circuits.