Advanced multi-recovery techniques for enhancing efficiency in hydrogen fuel cell-based energy systems: An empirical study

Hydrogen fuel cell-based systems offer a promising approach for efficient hydrogen energy utilization. On the basis of the traditional cogeneration system focusing on the heat recovery of fuel cell stacks, the innovative multi-recovery technology proposed in this paper further comprehensively considers the recovery of the cathode exhaust total heat (including sensible and latent heat), exhaust kinetic energy, power conversion device heat, and auxiliary components heat. An experimental platform was established to evaluate these technologies, with a primary focus on assessing the impact of exhaust latent heat recovery on system performance—marking the inaugural evaluation in this context. Experimental results reveal that the exhaust total heat recovery achieves up to 10.75 kW at an 85 kW output power of fuel, which is 4.30, 10.24, and 3.41 times greater than the recovery of exhaust kinetic energy, power conversion device heat, and auxiliary component heat, respectively. Additionally, increasing the fuel cell output power from 21 to 124 kW resulted in a total heat recovery improve by 149.44 %, with latent heat contributing 25.21 %. A reduction in cooling water temperature by 4–7 °C further enhanced latent heat recovery by 10.62 % to 36.90 %. Regarding operational impact, the exhaust total heat recovery reduces operating power by only 0.18 kW. Ultimately, the integration of these technologies resulted in a total system efficiency improvement of 8.82 % to 11.53 %, with a peak value of 97.31 %.