Residential Heat Pumps with OpteonTM XL20 / R-454C - System optimizations results [7]

A residential Heat Pump from serial production has been tested in an independent laboratory in Germany using R-454C refrigerant. The thermodynamic properties of the Low GWP A2L refrigerant OpteonTM XL20 (R-454C) together with compressor envelope data showed promising opportunities for this application.

Still at -30 °C evaporation temperature (corresponding with about -25 °C ambient temperature) a condensing temperature of 65 °C (corresponding with about 60 °C water flow temperature) could be achieved – sufficiently high for production of domestic hot water at the same time. That means additional electrical heater could be avoided.

Different system components and parameters have been varied and measured in laboratory and optimized, targeting to improve system energy efficiency and heating capacity. A thermodynamic model has been developed based on Modelica / Dymola that allows for adaption to different system configurations and for changing different system components and parameters to understand their influence on energy efficiency and system capacity, thus for an effective optimization of the whole system. This model might support Heat Pump OEM manufacturers improving their Heat Pump systems´ capacity and energy efficiency while saving R&D resources and time within the development process.

This presentation shows the main measurement results and the general features of the thermodynamic model. Finally, the main improvements in energy efficiency and system capacity are being discussed for a range of operating conditions.