Numerical study on the fast filling of on-bus gaseous hydrogen storage cylinder

Abstract

High-pressure gaseous hydrogen storage is used by bus manufacturers to meet the energy density requirements. However, a rapid filling rate is accompanied by the realization of the ideal filling time and may result in a significant temperature rise in cylinder. Excessive temperature in cylinder has negative impacts on the filling safety and the full endurance range of the hydrogen fuel cell vehicles (HFCVS). Therefore, it is of great practical significance to monitor and control the maximum temperature rise in cylinder. In this paper, a 2-dimensional (2D) axisymmetric model is used to simulate the fast filling (3, 5 min) and 10-min holding process of 150 L on-bus type III and type IV gaseous hydrogen storage cylinder. The HFCVS cylinders with nominal working pressure (NWP) of 35 and 70 MPa are both covered in this research considering the current use of vehicle cylinders for the on-board hydrogen storage system. The temperature evolution and the maximum temperature rises of both hydrogen gas and solid materials are all concerned to evaluate potential filling safety issues. The results show that the maximum temperature rise may occur in different areas for different type cylinders, which can be the region of the head dome junction or the caudal region of the cylinder. Additionally, the temperature rise of hydrogen gas reaches the highest value at the end of fast filling, and the temperature rise of hydrogen gas in type IV cylinder is much higher than that in type III cylinder. In contrast, the maximum temperature rises of fiber materials occur at the end of 10-min holding, whereas there are no significant differences between type III and type IV cylinders, accordingly the control strategies of filling for both type III and type IV cylinders should not be treated distinctively. This research will serve as input to advanced refueling regulations and standards improvement.