Air Hot water Thin metallic layers R Polyurethane foam = 4. Polyurethane foam (k = 0.025 W/m K) is used to insulate cylindrical water heaters. The polyurethane foam is sandwiched between two thin metallic layers as shown in the figure. The thickness of the polyurethane layer is 4 cm, while the internal radius of the tank is R = 40 cm. Assume that the internal metallic layer is always at the temperature of the hot water (55 C) and that the outer layer loses heat by convection to the surroundings at T = 10 C, with h = 50 W/mK. The length of the tank is 2 m and heat losses from the end surfaces are negligible. If the cost of energy is $ 0.10/kWh, determine the cost of the energy losses from the tank per day. Assume steady state. What would be the cost if there were no insulation? =