PEM fuel cell temperature management for high performance

Licentiate thesis, 2025

Addressing the thermal management challenges of low-temperature proton exchange membrane fuel cells (PEMFCs) is an important step to enable the decarbonization of heavy-duty transport with hydrogen as a fuel. Due to the low operating temperature of 60-90°C, PEMFC vehicles require large radiators to achieve sufficient heat rejection which makes alternative cooling solutions desirable. Other key challenges in the development of PEMFC like lifetime and cost are also significantly impacted by the thermal management system.
The presented project is part of a holistic approach to address thermal management and lifetime challenges in heavy-duty fuel cell vehicles. First a verified 0D/1D heavy-duty truck vehicle model with conventional cooling system has been developed to identify its thermal limitations and the resulting impact on the vehicle performance. Already at 20°C ambient temperature, severe thermal limitations require a PEMFC performance reduction of up to 46% to prevent overheating in the hill climb scenario investigated in this work. Integrating components like a braking resistor to substitute engine braking in the vehicle model shows that thermal management not only impacts the vehicle performance during uphill but also downhill driving. The identification of these limitations enabled the design of a highly integrated bubble column evaporative cooling solution that utilizes the PEMFC product water complementary to the established radiator cooling system. The project focus is on worst-case cooling conditions of high fuel cell load and elevated ambient temperatures. A collaborative development of an enhanced fuel cell model shall eventually allow for a detailed evaluation of the interdependency of thermal management, vehicle performance, degradation, fuel cell operation and auxiliary equipment over the lifetime of a vehicle. Moreover, the modular structure allows for the integration of these solutions in other heavy-duty vehicles.
This thesis presents a complementary technical background to the investigations done thus far. The results of the publications within this project are summarized and an overview of the planned future work is presented.