Modelling the view factor of a ‘grain-like’ observer near a tilted pool fire via planar approximation approach

•Planar approximation to view factor, F, expressed in terms of two sensitive parameters: α and β.•The larger the values of β, the closer the view factor predictions of PHAST 7.2 and planar approximations.•Large enough values of β would guarantee the observer receives a maximum view factor and hence maximum radiation.•F decreases (decays polynomially) with increasing observer distances away from the flame surface.•Both approximations were found to coincide for: β=48.961∘, X=30m, α=0.01, γ=0.77, L=12.14m, Θ=55.17∘, D=5m.