The water in an electric heater is maintained at 60 C. The tank is made of 6-mm thick type 316 stainless steel cylinder with 12-mm thick stainless steel end-plates. The inside dimensions of the tank are 60-cm diameter and 100-cm height. T=15 h = 8 W/m 60 1 0,6 d=0.612h 30.712 100 cm -6 mm 12 mm W The tank is covered with 5-cm thick fiberglass insulation. The surrounding air is at 15 C with a surface heat transfer coefficient of 8 Assuming the inner surface of the tank to be at 60 C, estimate the electrical mC* energy required during a 12-h period when no water is drawn from the boiler.