Waste heat recovery and storage using phase change materials for independent fuel cell preheating

This paper presents a novel waste heat recovery arrangement for proton exchange membrane fuel cells by integrating a phase change material (PCM)-based thermal storage system. The primary objective of this system is to capture the fuel cell cooling load during operation and utilize it to preheat the stack during start-up, thereby minimizing auxiliary power consumption and enhancing system efficiency. A case of a 6.5 kW fuel cell system is tested under controlled conditions, with coolant temperatures of 54 °C, 58 °C, and 62 °C, ensuring faster stack warm-up for the next operation cycle. The analysis quantifies thermal storage efficiency, preheating performance, and auxiliary power reduction to support this study. The results show that the proposed PCM-based heat recovery system outperformed conventional positive temperature coefficient heaters, achieving up to ~86 % shorter preheating time and almost 36 % reduction in parasitic energy associated with preheating the fuel cell. The proposed system also enhances the performance of the fuel cell in a warm start, which further underscores its potential for practical proton exchange membrane fuel cell applications. • Novel PCM-based LHS system for efficient PEMFC waste heat recovery and storage • RT-44HC PCM lowers coolant temperature up to 4.5 °C, boosting WHR efficiency. • LHS with 2.5 mm provision ensures rapid melting and lower system weight. • LHS system outperforms PTC heaters, with up to 86.4 % time and 35.7 % energy savings. • Scalable design boosts efficiency and warm starts, cutting parasitic energy use.