Enhanced dormancy due to para-to-ortho hydrogen conversion in insulated cryogenic pressure vessels for automotive applications

• Published in: International journal of hydrogen energy 2013-10, Vol.38 (31), p.13664-13672
• Main Authors: Peng, J.K., Ahluwalia, R.K.
• Format: Article
• Language: English
• Subjects: Alternative fuels. Production and utilization; Applied sciences; Automotive components; Conversion; Cryo-compressed tanks; Cryogenic hydrogen storage; Dormancy; Endothermic reactions; Energy; Exact sciences and technology; Fuels; Hydrogen; Hydrogen loss; Hydrogen-based energy; Para-to-ortho conversion; Pressure vessels; Reaction kinetics; Tanks; Thermodynamics
• ISSN: 0360-3199; 1879-3487
• DOI: 10.1016/j.ijhydene.2013.08.039

A dynamic model has been developed to characterize dormancy and hydrogen loss from an insulated cryogenic pressure vessel that is filled with 99.79%-para liquid hydrogen to reach supercritical conditions. The model considers the thermodynamics and kinetics of the endothermic para-to-ortho conversion that occurs when the stored H2 heats after the vessel is exposed to ambient conditions for an extended time. The thermal, thermodynamic, and kinetic aspects of the model were validated against experimental data obtained on a 151-L tank designed for service at nominal pressures up to 350 bar. Depending on the initial pressure, temperature, amount of H2, and the rate of heat gain from the ambient, the endothermic para-to-ortho conversion can extend the loss-free dormancy time by up to 85%. Under conditions in which the endothermic conversion does not materially affect dormancy, it can still significantly reduce the H2 loss rate and it can even introduce a secondary dormancy period. •Modified REFPRIOP for thermodynamics of isomer transitions.•Kinetics of para-to-ortho conversion in a 151-L tank.•Up to 85% enhancement in dormancy due to endothermic para-to-ortho conversion.•Reduced hydrogen loss due to para-to-ortho conversion.