Experimental study on multi-mode start-up and dynamic characteristics of proton exchange membrane (PEM) electrolyzer system

This study experimentally investigates and comparatively analyzes the dynamic performance of a proton exchange membrane (PEM) electrolyzer during cold start, hot start, and load regulation. The experimental comparison specifically includes three cold start-up strategies: direct, single-step, and double-step; two hot start-up approaches: direct and multi-step; and two load regulation modes: direct and stepwise. To comprehensively evaluate the dynamic performance of the PEM electrolyzer, this study adopts indicators such as voltage rise rate, average efficiency, and average hydrogen production rate for assessment. To objectively determine the weights of each indicator, the entropy weight method was adopted. Subsequently, the Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) was used to calculate the closeness coefficient of each operational strategy to the ideal solution, thereby quantifying their overall performance ranking. Results show that the single-step cold start-up strategy exhibits the best overall performance, with its voltage rise rate, average efficiency, and average hydrogen production rate being 2.32 mV/s, 69.68%, and 1.324 mmol/s, respectively. The multi-step hot start-up strategy demonstrates superior overall performance compared to the direct hot start-up, with corresponding indicators of 4.25 mV/s, 71.92%, and 1.315 mmol/s, respectively. The multi-step load regulation strategy exhibits significantly better overall performance than the direct regulation method, particularly during load-decreasing operations. The relative closeness coefficients are 0.2816 and 0.7184 for direct and multi-step load increasing, respectively, and 0.0196 and 0.9804 for direct and multi-step load decreasing, respectively. This study provides both experimental evidence and a comprehensive assessment framework for optimizing the dynamic operation strategies of PEM electrolyzers.