Impacts of initial temperature and cylindrical obstacles on the dispersing flammable limits of accidental methane releases in an LNG bunkering terminal

•Dispersing flammable limits of accidental methane releases were investigated.•The lean flammable limits (LFLs) were compared for TCH4,0 = −50 and −150 °C.•The effect of cylindrical obstacles on the gas dispersion was compared.•The LFLs distributions were analyzed with the vortical flow structure. This paper presents a numerical study on the dispersing flammable limits with respect to the initial methane releases at TCH4,0 = −50 and −150 °C in the crosswind of ambient air according to the arrangement of (a) No Tank, (b) Tank I, (c) Tank II, and (d) Tank I and II on the ground. To provide a better physical insight on the dispersion behaviors of the methane releases, the spatial distributions of the quasi-averaged methane concentration and flow fields were mainly analyzed using 3-D large eddy simulations. Consequently, the results of both the parameters can be summarized in that the vortex characteristics of the rotating direction and vorticity generated by the interactions not only between the crosswind and cylindrical obstacles but also between the crosswind and releasing methane flows played important roles in determining the dispersing flammable limits depending on the mixing characteristics.