Thermal Management Concepts for Fuel Cell Electric Vehicles Based on Thermochemical Heat Storages

Abstract

Due to the heating and cooling requirement of the passenger compartment and powertrain components such as the fuel cell, battery, electric motor and power electronics, the fuel cell electric vehicles have increased vehicle thermal management complexity compared to the conventional cars with internal combustion engines. The use of different systems for the cooling and heating of the different components results in increased weight and higher costs. Additionally, the required energy for the thermal management system is provided by the fuel cell and the battery, which is critical to fuel cell vehicle performance and causes reduction in the electric range. The DLR Institute of Vehicle Concepts examine an optimized thermal management system for the fuel cell electric vehicles, which uses thermochemical heat storages in order to minimize the electrical energy required by the thermal management system compared to current solutions. Current work details various thermal management concepts based on thermochemical heat storages, which are able to store the waste heat and generate not only heating but also cooling. In order to survey the suitability of these thermal management concepts for the fuel cell electric vehicles, an overall vehicle simulation model using the AlternativeVehicles library is developed. According to the data of a fuel cell range extender vehicle, which is based on the Smart Fortwo vehicle and uses a high temperature polymer electrolyte membrane fuel cell as a range extender unit, the overall vehicle simulation model has been parameterized and validated with experimental data. Based on various driving cycles and thermal boundary conditions the reduction in the energy consumption using the different thermal management systems is demonstrated. It is shown that the operating range of the fuel cell electric vehicle can be extended by up to 17 per cent.