New working fluid R-474A for BEV thermal management [8]

Battery electric vehicles (BEV) will have a significant share in future vehicle fleets. The acceptance of electrified vehicles by the market is essentially dependent on the achievable driving range of the vehicles.

In order to maximize the range of BEVs, the energy efficiency becomes more important. Since the energy density of batteries is still limited and the waste heat flows in BEVs are lower than in internal combustion engine (ICE) vehicles, the energy and waste heat must be used as efficiently as possible as part of the thermal management. This includes the increase of heat pumps to further increase the thermal system efficiency.
Automotive refrigerant blends using the new component R-1132(E) enable the thermal system to expand the operation conditions in the heat pump (HP) mode down to ambient temperatures of -30 °C while staying subcritical in air conditioning (AC) mode. The advantageous pressure and temperature behavior delivers high capacity at great efficiency across all conditions. This high capacity provides high cabin comfort and cooling or heating of relevant vehicle systems at the same time.

The lecture presents the thermophysical, chemical and material compatibility properties of the automotive refrigerant R-474A, a blend containing R-1132(E) and R-1234yf. Simulation results and various tests on component and system level shed light on efficiency and performance improvements compared to existing BEV thermal management solutions using the refrigerants R-1234yf and R-744. A summary of current development programs and an outlook on the next steps concludes the presentation.