Different strategies in an integrated thermal management system of a fuel cell electric bus under real driving cycles in winter

Abstract

Due to the climate crisis and the restriction measures taken in the last decade, electric buses are gaining popularity in the transport sector. However, one of the most significant disadvantages of this type of vehicle is its low autonomy. Many electric buses with proton-exchange membrane fuel cells (PEMFC) systems have been developed to solve this problem in recent years. These have an advantage over battery-electric buses because the autonomy depends on the capacity of the hydrogen tanks. As with batteries, thermal management is crucial for fuel cells to achieve good performance and prolong service life. For this reason, it is necessary to investigate different strategies or configurations of a fuel cell electric bus's integral thermal management system (ITMS). In the present work, a novel global model of a fuel cell electric bus (FCEB) has been developed, which includes the thermal models of the essential components. This model was used to evaluate different strategies in the FCEB integrated thermal management system, simulating driving cycles of the public transport system of Valencia, Spain, under winter weather conditions. The first strategy was to use the heat generated by the fuel cell to heat the vehicle's cabin, achieving savings of up to 7%. The second strategy was to use the waste heat from the fuel cells to preheat the batteries. It was found that under conditions where a high-power demand is placed on the fuel cell, it is advisable to use the residual heat to preheat the battery, resulting in an energy saving of 4%. Finally, a hybrid solution was proposed in which the residual heat from fuel cells is used to heat both the cabin and the battery, resulting in an energy saving of 10%.