Abstract
Preventing abnormal shut-off before the completion of refueling is essential to minimizing vapor emissions from fuel tanks into the atmosphere. Previous investigations of abnormal shut-off during refueling have primarily relied on CFD analysis of fuel tank systems. However, there has been limited discussion from a phenomenological perspective that directly links the shut-off mechanism to the pressure balance between the filler tube and the tank. The objective of this study is to establish a pressure-based method for determining abnormal shut-off during refueling by comparing the fuel-pushing pressure at the filler tube (critical refueling pressure) with the transient internal fuel tank pressure (transient tank pressure). The proposed method determines abnormal shut-off when the critical refueling pressure becomes lower than the transient tank pressure, rendering it impossible to push the delivered fuel into the tank. The critical refueling pressure was derived theoretically by modeling the flow field inside the filler tube and predicting the total pressure immediately upstream of the outlet. The transient tank pressure during refueling was predicted using an equation for pressure loss in the vapor-displacement line of the fuel tank. Finally, the respective pressures were calculated for actual fuel tank systems using the derived prediction formulas and were compared with measured values. The predicted values showed good agreement with the experimental data, and demonstrated the effectiveness of the proposed pressure-based method for determining abnormal shut-off during refueling.
