Proposed Solution for Improving Efficiency in Fuel Cell Power Systems Based on Short-Circuit Energy Recovering

This work presents a design solution for energy recovery in fuel cell power systems, validated through simulation tools to improve energy efficiency. The effort is specifically applied to low-temperature proton exchange membrane fuel cell (LTPEMFC) systems that employ short-circuit (SC) activation techniques to enhance catalytic activity during operation. The design addresses the energy supply discontinuity problem to the load during SC time intervals, allowing energy normally dissipated through an electronic switch to be supplied to the balance of plant (BOP), thereby minimizing energy losses and increasing system efficiency. A model-based design approach using numerical simulation tools was applied to validate the feasibility of the proposed system for a 1 kW fuel cell. Results show greater energy recovery at lower operating power (50 W), reaching 4.27% and 2.38% for theoretical and simulation validation, with the following system parameters: 9.00 V SC voltage, 100 ms SC pulse duration, and 10 s SC interval. Previous sensitivity studies reveal that the optimal parameter combination of 100 ms SC pulse duration, and 0.5 s SC interval, that combined with 9.00 V SC voltage, yields 34% energy recovery at 50 W. The equivalent series resistance (ESR) aging in energy storage supercapacitors affects SC effectiveness more than capacity degradation over 5000 h of LTPEMFC stack operation. The proposed method enables LTPEMFC operation expansion to lower power conditions, compensating for damage in idle and start-stop cycling modes. Future work involve physical implementation and experimental validation.