Design and optimization of thermal strategy to improve the thermal management of proton exchange membrane fuel cells

Abstract

This paper briefly recommends the working principle of the cooling system of the fuel cell engine (PEMFC), studies the control strategy of the thermostat in the cooling system, which couples the electric heater to shorten the water temperature fluctuation and save time. Cooling PEMFC is a challenge due to the small temperature differences between the stack and the environment. The fluctuation of water temperature and time transformation will lead to the change of system power, and further impact on the system's dynamic performance, reliability and life. Firstly, the simulation and experimental verification of cooling system of 30 kW fuel cell engine are presented. The influence of mechanical paraffin thermostat and electronic thermostat with certain control logic on the outlet temperature of the engine system stack is contrasted. Severe water temperature fluctuations will decrease the life of the system. Furthermore, the PID control and fuzzy PID control of temperature control valve are adopted, and the control method of coupling electric heater is used to solve the temperature fluctuation when the water temperature at the outlet of the stack is mixed. The results indicate that compared with the paraffin thermostat and PID controller, the fuzzy PID controller can obviously decrease the temperature fluctuation during the mixing of water temperature. Further, in different external environments, the fuzzy PID control coupling electric heater can reduce the temperature difference fluctuation to 0.5 °C when the system mixes large and small circulating water temperatures. The optimized coupling control strategy can decrease the water temperature fluctuation of the cooling system, thereby optimizing the temperature management of the cooling system, and significantly extending the power and reliability of the system.