2. A mild steel tank of wall thickness 10 mm contains water at 90°C. Calculate the rate of heat loss per m² of tank surface area when the atmospheric temperature is 15°C. The thermal conductivity of mild steel is 50 W/mK and the heat transfer coefficients for inside and outside the tank are 2800 W/m²K and 11 W/m²K respectively. Calculate also the temperature of the outside surface of the tank.

Fig: 1