Left: bridge with cars overhead surrounded by water; right: the BTM logo

CO2-BTM – Combined refrigeration/cooling circuit with environmentally friendly refrigerant CO2 for vehicles with fuel cells

The CO2-BTM project targets on increasing the maximum driving range of fuel-cell powered electric vehicles. By combining the high-/ low temperature and the cooling medium circuits into one system, the energy efficiency as well as the hydrogen consumption are optimized. As conventional approaches cannot be used for controlling this system, a novel and model-based control algorithm with 2 degrees of freedom is developed and used. In order to guarantee efficient heat-pump operation even for temperatures below 5 °C, the environmentally friendly cooling medium CO2 (R744) is used to replace the conventional cooling medium R134a.