Question

A thin electrical heater is wrapped around the outer surface of a long cylindrical tube whose inner surface is maintained at a temperature of 6°C. The tube wall has inner and outer radii of 24 and 78 mm, respectively, and a thermal conductivity of 10 W/m · K. The thermal contact resistance between the heater and the outer surface of the tube (per unit length of the tube) is R ′t,c=0.01 m⋅K/WRt,c ′=0.01 m·K/W. The outer surface of the heater is exposed to a fluid with T_∞ = −10°C and a convection coefficient of h = 100 W/m² · K. Determine the heater power per unit length of tube required to maintain the heater at T_o = 25°C.

Answer 1