Improving driving range for FCEVs by use of an innovative metal hydride air-conditioning system

Abstract

Driving range of alternative powered vehicles, such as fuel cell electric vehicles (FCEV), became a core requirement and an unneglectable selling argument. Besides the energy efficiency of the powertrain itself and the body specifications, such as weight and air resistance factor, the auxiliaries need to be focused to extend vehicle range. As cooling and heating the cabin is one of the main energy consumers this presentation will elaborate an innovative concept to support or even substitute the vehicles conventional air-conditioning. The system is based on the reversible reaction of metal hydrides (MH) with hydrogen and uses the pressure difference between a high-pressure hydrogen tank and the fuel cell to provide heat and cold without producing water. So, without changing the chemical state of the hydrogen. Based on an existing lab-scale prototype, a mathematical model was validated and been implemented into the simulation platform 'KULI'. This contribution discusses the integration strategy of such a metal hydride air conditioning system into a FCEV and elaborates its impact on energy consumption and corresponding driving range in numerical simulations. Integrating a coolant to air heat exchanger into the HVAC box allows using both cold coolant from desorption side of the MH-reactor in summer and hot coolant from the absorption side in winter. Our results demonstrate significant energy saving potentials by reducing the utilization of electric climate compressor and electric PTC heater. Simulations also show that these benefits are not achieved by reducing passenger comfort, but instead both cool-down and warm-up times are even reduced.