Efficient harvesting of low-grade waste heat from proton exchange membrane fuel cells via thermoradiative power devices

A hybrid electric power generation system involving a thermoradiative power device (TPD) and a proton exchange membrane fuel cell (PEMFC) is proposed, in which the TPD can efficiently convert low-grade waste heat produced by PEMFC into electricity. Accordingly, a theoretical model is developed to investigate the output performance characteristics and the optimal design of the proposed system. The model predicts that the hybrid system can generate a maximum power density of 0.367 W/cm(2) when operated at 353.15 K, possessing better output performance than other previously proposed PEMFC-based hybrid systems. The peak power density of the hybrid PEMFC-TPD device is around 1.30 times that of the PEMFC, suggesting significantly improved overall performance of the system. Additionally, the effects of radiative extraction efficiency and bandgap for the TPD to achieve optimal performance are investigated. Importantly, the optimal operating regime and the critical parameter designs concerning the hybrid system are identified, offering theoretical guidance for improving system performance. These findings provide important guidelines in designing high-performance coupled heat-to-electricity energy harvesting systems.