1. Consider the electric hot water heater in the figure below. The tank is insulated with 6cm

thick layer of insulation with a kinsul-0.03 W/m-°C. The convection heat transfer coefficients

on the inner and outer surfaces of the heater are 50 and 12 W/m²-°C, respectively. Determine

the cost of electricity required per year to maintain a water temperature of 55°C if the

surrounding air temperature is at 27°C. Assume a cost of electricity of 0.12 $/kW-hr.

Neglect radiation heat transfer and the thermal resistance of the tank. Assume the flow of

water to be zero. Also neglect the heat transfer from the top and bottom of the tank.