Consider a gas-fired boiler in which five coiled thin-walled, copper tubes of 25-mm diameter and 8-m length are submerged in pressurized water at 4.37 bars. The walls of the tubes are polished and may be assumed to be isothermal. Combustion gases enter each of the tubes at a temperature of T_m,i = 700°C and a flow rate of m = 0.08 kg/s, respectively.

Determine the tube wall temperature Ts and the gas outlet temperature T_m.o for the prescribed conditions. As a first approximation, the properties of the combustion gases may be taken as those of air at 700 K.

Steam Boiler- T, Water, Psat Gas line (L, D) (1 of 5) Tme m. Tmi