The tube bank of a steam condenser consists of a square array of 400 tubes, each of diameter
D = 2r1 = 6 mm.
1. If horizontal, unfinned tubes are exposed to saturated steam at a pressure of p = 0.15 bar and the tube surface is maintained at Ts = 25°C, what is the rate at which steam is con- densed per unit length of the tube bank?
2. If annular fins of height h = r2 - r1 = 1 mm, thickness t = 1 mm, and pitch S = 2 mm are added, determine the minimum condensation rate per unit length of tubing.