Title: Gas and Wall Temperature Disparities While Fueling and Defueling Tanks
Publisher: Spanish Hydrogen Association
Publication Year: 2016
JRC N°: JRC100669
URI: http://www.whec2016.com/index.php
Type: Articles in periodicals and books
Abstract: In the context of defining protocols for the fueling or defueling of composite material hydrogen pressure tanks, it is crucial to not exceed certain temperature limits. 85°C during fuelings is the upper boundary that the gas temperature should not exceed during the refueling of hydrogen cars in the standard SAE J2601-2014. In the same manner, usual defueling recommendations suggest that the lower gas temperature boundary is-40°C. The project HyTransfer, an FCH JU funded pre-normative research project, aims at showing that setting these two limits on the wall temperature rather than on the gas temperature permits to diminish operational constraints and therefore obtain a significant improvement of the overall costs for fueling and defueling. In this context, the paper will show both for fueling and defueling, how the temperature of the tank wall can be estimated. The analysis of this temperature will be based on Computational Fluid Dynamics (CFD), experimental results and simple thermodynamical modeling. When analyzing the gas and wall temperature differences, it is first necessary to distinguish between cases with homogeneous and cases with heterogeneous gas temperature. Therefore, the paper will first show indicators of temperature disparities in the gas, followed by analyses of the gas and wall temperature differences by splitting the analysis in two cases: homogeneous and heterogeneous gas temperature. When the gas temperature can be considered as homogeneous, one can show how the wall temperature is reduced to the correct determination of the heat exchange parameter between the gas and wall. In the context of heterogeneities of temperature in the gas (fueling at low speed and defueling in general), the paper will provide correlations linking the gas and wall temperature differences to simple tank geometry parameters and fueling or defueling conditions. In the end, the problem of the determination of hot or cold spots in the tank wall will have been fully covered and reduced to the computation of a thermodynamical modeling combined with correlations so that highly time-demanding computations such as 3D CFD are not mandatory.
JRC Directorate:Energy, Transport and Climate

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