Effects of filling strategies on hydrogen refueling performance.

In order to ensure the safety of hydrogen refueling systems and fuel cell vehicles under various filling conditions, the filling parameters are usually set very conservatively, leading to waste energy consumption and investment. The lumped parameter hydrogen gas model and one-dimension tank wall model of the hydrogen filling process previously proposed by our team were extended and improved to the entire hydrogen refueling system by considering the Joule-Thomson effect, kinetic energy and using a more accurate model of the heat transfer coefficients between the inner tank wall and hydrogen gas and between the outer tank wall and ambient. Based on our validated model, the effects of constant and two-stage average pressure ramp rates (APRRs) and precooling/inlet temperatures on refueling performances were investigated, respectively. Compared with the optimal filling strategy of the reference paper, where a constant APRR is the best, our two-stage APRRs can further reduce the cooling power for various inlet temperatures without increasing the cooling energy. For example, maximum cooling power can be reduced by 23.8% at the inlet temperature of −20 °C. Compared with the previous research result obtained using a constant inlet temperature solved by the analytical solution, the two-stage inlet temperatures can further reduce the cooling power by 16.3% at an APRR of 0.428 MPa/s without increasing the cooling energy. • A thermodynamic model for a hydrogen refueling system is improved and well validated. • Joule-Thomson effect, kinetic energy and accurate heat transfer model are considered. • Effects of two-stage average pressure ramp rates and inlet temperatures are studied. • Two-stage strategies can reduce cooling power without increasing cooling energy. [ABSTRACT FROM AUTHOR]