# Calculation Methods - Tube Bundle (Flow around tubes)

The pressure loss around a tube bundle is calculated according to the Delaware method. ΔP = 0.5 fD G2 (NBaffleCount+1) Dis / (ρ Dh) The friction factor is determined from regression analysis of the charts provided in Serth [12] The variables used in the above equations are described below. G is the mass flux. ρ is the fluid density. fD is the friction factor (Darcy). Dis is the inside shell diameter. Dh is the hydraulic diameter. NBaffleCount is the number of baffles.