HAB5-e

VDI Heat Atlas eReference

a_u is calculated by additive superposition of the heat transfer coefficient a_one,nb and the convective contribution a_one,conv, both for a single tube, that is,
a_u = a_one,nb + f · a_one,conv

where the factor f depends on the size of the tube bundle and the anticipated inlet flow velocity, where 0.5 ≤ f ≤ 1.