Search

This study compares four computational fluid dynamics (CFD) models, i.e. k-ε, RSM, SAS, and LES, to simulate temperature non-uniformity during hydrogen tank refuelling. Three grids with a total number of control volumes of 64k, 363k, and 2.9 M were used. The maximum dimensionless wall distances, y + , were 80, 5 and 2.5, respectively. The predictive capability of the models was assessed by recommended statistical indicators using ten thermocouple locations during 620 s of the experiment. The comparative analysis demonstrated a better predictive capability of temperature non-uniformity and stratification by the LES model and a shorter simulation time. It is concluded that meshes with y + larger than 80 would overpredict the average hydrogen temperature while meshes with y + < 5 provide a good simulation accuracy. The results underline the importance of the turbulence model choice and the numerical grid resolution for proper prediction of temperature non-uniformity during hydrogen tank refuelling. • Comparative analysis of k-ε, RSM, SAS, and LES models in refuelling simulations. • Three meshes are studied to understand their effect on model predictive capability. • The performance of the models is evaluated by recommended statistical indicators. • LES model is the fastest and most accurate in predicting temperature non-uniformity. [ABSTRACT FROM AUTHOR]

A novel element for gas–liquid contact, a plate with rectangular windows was designed to enhance absorption process. Coexistence and interaction of wall‐bounded films and confined free films named as “twin‐liquid films” were observed on the plate. Volume of fluid (VOF) method was used to simulate its flow behavior. Flow phenomena such as flow around a step‐in, jet impingement, varicose waves, and sinuous waves were observed. Different from thin films flow on an unperforated plate, larger mean velocity, thinner film thickness, more intensive capillary waves, and stronger vorticity on the free surfaces were detected inside the window, and the disturbances could propagate over the whole plate. Three‐dimensional simulation results generally agreed with our experimental observations and further demonstrated complex wavy structures both inside and outside the window. The results would broaden traditional knowledge of liquid films flow and clarify the mechanism of mass transfer intensification for the plate with windows. © 2017 American Institute of Chemical Engineers AIChE J, 64: 1458–1468, 2018 [ABSTRACT FROM AUTHOR]