Heat Pumps and Optimized Thermal Management Strategies in Battery-Electric Rail Vehicles—Modeling and Evaluation

Abstract

Battery-electric rail vehicles are a sustainable alternative for diesel-powered vehicles on tracks without catenary. However, the energy demand to heat and cool the cabin limits the vehicle range, and the applied synthetic refrigerants are environmentally harmful. Therefore, this paper studies how energy demand and load on the battery in battery-electric rail vehicles can be reduced using heat pumps with natural refrigerants and efficient thermal management. A heat pump and thermal car body model are developed and validated, which calculate the energy demand in battery-electric rail vehicles. In these models, an optimized thermal management strategy is implemented, which changes the cabin set-point temperature based on catenary availability. For a two-car battery-electric rail vehicle in the climate zone II of Central Europe, the annual thermal energy demand is up to 110 MWh. The application of a heat pump with R290 (propane) can reduce the annual electrical energy demand for heating and cooling by up to 55%. The load on the battery can be mitigated further with the optimized thermal management strategy, reducing the equivalent full cycles by 3%. Overall, the heat pump operation and efficient thermal management strategy lead to higher vehicle range and flexibility in daily operation, increasing the acceptance of battery-electric rail vehicles.