Math Problem Solver

Q/ Consider a 2-m-high electric hot water heater that has a diameter of 40 cm and

maintains the hot water at 55°C. The tank is located in a small room whose average

temperature is 27°C, and the heat transfer coefficients on the inner and outer surfaces

of the heater are 50 and 12 W/m2

· °C, respectively. The tank is placed in another

46-cm-diameter sheet metal tank of negligible thickness, and the space between the

two tanks is filled with foam insulation (k = 0.03 W/m · °C). The thermal resistances

of the water tank and the outer thin sheet metal shell are very small and can be

neglected. Determine the rate of heat loss from the hot water tank. After that, we

added another insulation for the hot water tank, which is consisting of 3-cm-thick

fiberglass insulation (k = 0.035 W/m · °C) and its large enough to wrap the entire

tank. Again, determine the rate of heat loss from the hot water tank. Finally, find

how much energy will be saved in Watt?