On the benefit of integrating vortex tubes in PEMFC system for preheating hydrogen in FCEV technologies

Using hydrogen fuel cell electric vehicles equipped with proton exchange membrane fuel cells could reduce greenhouse gas emissions from the transportation sector. Heating is necessary for a safe cold start-up process, but current methods consume a lot of electrical energy. In this research, it is proposed to heat the hydrogen by using vortex tubes to separate the compressed hydrogen into a low and a high enthalpy streams and by using a heat exchanger to pump heat from the ambient into the cold stream. This system uses only the excess pressure available from the hydrogen tank as the motive power. A real gas thermodynamic model coupled with a genetic algorithm is used to maximize the hydrogen inlet temperature to the fuel cell for three different configurations of vortex tubes and heat exchangers for a 4-passenger 100 kW fuel cell electric vehicle while minimizing the heat exchanger conductance and area product. For hydrogen stored at -30 degrees C, vortex tubes can increase the hydrogen feeding temperature from -1.6 degrees C (Joule-Thompson heating in an isenthalpic throttling valve) to up to 18.3 degrees C, which corresponds to a heating power of 622 W.(c) 2022 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.