Flow analysis and development of a model to simulate transient temperature of hydrogen from pre-cooler to on-board storage tank during hydrogen refueling

摘要

Hydrogen energy is expected to play an important role in energy transition policies. Currently, the utilization of hydrogen energy is mainly in the field of mobility associated with fuel cell electric vehicles (FCEVs). To increase the utilization of FCEVs, it is essential to develop a method for safely refueling hydrogen into on-board storage tanks which have a temperature limitation. Therefore, it is necessary to understand the flow and heat transfer characteristics of hydrogen to keep the temperature lower than the limitation. In this study, a model for predicting the temperature of hydrogen at the pipeline outlet was developed based on flow characteristics analysis. It is revealed that the flow in a pipeline can be considered as incompressible and that the turbulence model can be applied with respect to pressure, temperature, and pipeline diameter. The proposed model is based on energy balances of the pipeline and the flowing hydrogen. Analogous methods are compared to obtain heat transfer coefficient required for thermal analysis. Although there is a difference in the heat transfer coefficient with respect to the analogous methods, little difference is found in the hydrogen temperature. Additionally, it is found that the equivalent length can be used to account for the thermal mass of the pipeline and the experimental results can be accurately simulated using a relatively large external heat transfer coefficient.