Utilizing hydrogen pressure energy by expansion machines – PEM fuel cells in mobile and other potential applications

• Published in: Applied energy 2023-08, Vol.343, p.121056, Article 121056
• Main Authors: Singer, Gerald, Köll, Rebekka, Aichhorn, Lukas, Pertl, Patrick, Trattner, Alexander
• Format: Article
• Language: English
• Subjects: Design concept; Expansion machine; Potential analysis; Pressure energy; Reciprocating piston expander; Turbomachine
• ISSN: 0306-2619; 1872-9118
• DOI: 10.1016/j.apenergy.2023.121056

•Systematic analysis of expansion machines types for fuel cell application.•The driving range can be increased by over 3% on complete tank filling.•Intermediate superheating reduces the size of the cooling system by over 3.5%.•A single stage reciprocating piston expander is detailed in a design concept.•The piston expander delivers 10 kW between 700 and 142 bar tank pressure. Hydrogen is an important energy carrier for a future without fossil fuels, but PEM fuel cell systems have to utilize the entire available energy as efficiently as possible. Hydrogen is typically stored at a maximum pressure of up to 700 bar and is supplied to the anode system at about 15 bar. Normally, a pressure reduction valve expands the hydrogen between 700 and 15 bar, but the pressure energy is unused during expansion. In this paper, different expansion machines are analyzed and the most attractive concepts are studied in detail to regain the expansion energy. Finally, a piston expansion system concept is designed with an estimated power output of 10 kW and a driving range increase of 2%, reflecting the high potential for efficiency improvement.