Consider a water pipe of length L = 17 m, inner radius r₁ = 15 cm, outer radius r₂ = 20 cm, and thermal conductivity k = 14 W/m·K. Heat is generated in the pipe material uniformly by a 25-kW electric resistance heater. The inner and outer surfaces of the pipe are at T₁ = 60°C and T₂ = 80°C, respectively. Obtain a general relation for temperature distribution inside the pipe under steady conditions and determine the temperature at the center plane of the pipe.