Off-Design Performance Analysis of a Turbocharged PEMFC System for Aviation

Abstract The civil aviation industry is under increasing pressure to reduce its environmental footprint, driven by stringent regulations aimed at limiting carbon emissions and promoting cleaner energy alternatives. In this context, hydrogen technologies have emerged as a promising solution to replace conventional combustion engines, offering the potential for zero-emission power generation. This paper investigates the performance of a turbocharged proton exchange membrane fuel cell system (TC-PEMFC) designed for aviation. UNIGE-TPG previously explored various alternative layouts of the TC-PEMFC, comparing their advantages and limitations. Based on the outcomes of this study, a single-shaft turbocharger designed for cruise at 15,000 ft is adopted here for integration with the PEMFC. This solution makes it possible to cover a wide range of power, while limiting the number of components in the system, two features that are very important for aircraft applications. Considering this solution, an off-design analysis is carried out to understand how variations of the ambient conditions affect the performance of the TC-PEMFC. This analysis is based on simulation results of a MATLAB-Simulink dynamic model of the whole system, including anode and cathode loop, cooling circuit and control logics. The model is used to simulate the TC-PEMFC under varying ambient conditions experienced during different phases of flight, defining its operational range. Different ambient conditions are determined by combining four values of pressure (1, 0.75, 0.50, and 0.25 bar) with six values of temperature (−50, −25, 0, 15, 30, and 40 °C). For each condition, the system is tested across a wide range of PEMFC current, from 30% to 100% of its nominal value, and all constraints are monitored to verify if PEMFC and TC can be properly operated. The results reveal that, as expected, the system flexibility is higher for conditions that are closer to its design point of 15,000 ft, where the system can cover the whole power range with no issues. On the other hand, the most significant limitations are found for high temperatures and low pressures, a combination that should not occur during flight. Analyzing the system performance, it can be observed that the net efficiency is always very high, being over 46% for maximum power load and increasing at part load. Regarding the influence of ambient conditions, the efficiency grows for lower temperatures and higher pressures, two conditions that are beneficial for the compressor. This effect is more pronounced at lower loads, with efficiency dropping by 2% when pressure decreases from 0.75 to 0.50 bar at nominal load, and by 3% at 50% load. These findings provide valuable insights into the performance of PEMFC-TC systems and highlight their potential as a reliable, low-emission power generation solution for the future of sustainable aviation.