Experimental and numerical study of the temperature evolution in hydrogen cylinder under fast-refueling process

Abstract

Hydrogen has been considered a feasible energy carrier for fuel cell vehicles (FCVs), which offers a clean and efficient alternative for transportation. The hydrogen is filled from high-pressure stations into hydrogen storage systems (HSS) in FCVs. During the refueling of high-pressure hydrogen, it can cause a rapid increase in temperature in the HSS due to the thermal characteristics of the system leading to safety problems. For safety reasons, the tank's maximum temperature and fueling pressure are limited to less than 85 oC and 125% of the vessel design pressure, respectively. This paper presents the fast-filling process of hydrogen tanks through experiments and simulations based on Computational Fluid Dynamics (CFD). Several critical parameters, such as the initial pressure, the initial temperature of hydrogen, and the filling rate that can contribute to the temperature rise, are investigated during the fast-filling process. The temperature within the tank increase with the decrease of initial pressure and the increase of ambient temperature with less filling time. In the case of a linear pressure increase from 2 to 35 MPa within 180 s at the ambient temperature of 20 oC, the maximum temperature reached 82.97 °C. In addition, the average velocity of the inlet gas of the hydrogen cylinder increases to 202.41 m/s rapidly in the first second and then decreases to 14.3 m/s slowly for the remaining filling process. For an ambient temperature of 40 oC, the maximum temperature can reach 101.24 oC during the process except for the first 10 s when the gas temperature within the tank was consistently above 85 oC, causing significant damage to the cylinder. As a result, reasonable and effective fast-filling strategies are designed to ensure safety at high ambient temperatures.