Energy saving control and operation strategy analysis of thermal coupling system of fuel cell and metal hydride tank

The thermal coupling system (TCS), where the heat generated by proton exchange membrane fuel cell (PEMFC) is transferred to the metal hydride (MH) tank, has been investigated extensively and proved beneficial to system compactness as well as capital cost. However, there is a lack of attention to the regulation of hydrogen desorption to increase the efficiency of hydrogen-to-power/heat (hh-p), especially when the TCS is used in a distributed energy system (DES) combining power and heat. In this study, an energy saving control strategy for a TCS applied in DES is proposed to increase the hh-p on the premise of the satisfaction of cosine-form hydrogen demand. The threshold temperature is introduced to characterize the maximum of hh-p, and a prediction framework of threshold temperature for arbitrary signal is proposed based on its functional relationship with five operation parameters and Fourier decomposition method (FDM). The operation strategy of two-tank TCS is also discussed. The results indicate that up to 7.26 x 103 kJ more heat could be utilized by energy saving control strategy compared with the reference case. The relative error of predicted threshold temperature within 0.14% is obtained for a square wave and aperiodic signal, verifying the generalization capability of the proposed framework. Besides, the operation strategy that the rated hydrogen demand is supplied by both MH tanks, is suggested in a two-tank TCS to increase the hydrogen utilization and extend the supply duration.& COPY; 2023 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

Automated summary

The thermal coupling system (TCS), which transfers the heat generated by proton exchange membrane fuel cell (PEMFC) to a metal hydride (MH) tank, has been proven to be beneficial in terms of system compactness and capital cost. However, there has been limited attention given to regulating hydrogen desorption to increase the efficiency of hydrogen-to-power/heat (hh-p), especially in distributed energy systems (DES) that combine power and heat. This study proposes an energy saving control strategy for a TCS applied in a DES, aiming to increase the hh-p while satisfying the cosine-form hydrogen demand. A threshold temperature is introduced to represent the maximum hh-p, and a prediction framework for the threshold temperature is proposed based on its functional relationship with five operation parameters and the Fourier decomposition method (FDM). The study also discusses the operation strategy of a two-tank TCS and suggests supplying the rated hydrogen demand using both MH tanks to increase hydrogen utilization and extend the supply duration.