Question
please answer in paper p3-28
Assuming the copper is isothermal, find the copper temperature. Take the electrical resistivity of copper to be constant at 2.1 times 10-8 Ohm · m. The wall of a submarine is 1-in-thick stainless steel (AISI 304) insulated on the interior with a 1.5-in. layer of polyurethane foam (k = 0.017 Btu/h·ft· degree F). The heat transfer coefficient on the interior is 3.7 Btu/h·ft· degree F. At full speed, the exterior heat transfer coefficient is 135 Btu/h·ft· degree F. The sub is approximately cylindrical with the length 240 ft and the outer diameter 30 ft. If the seawater is at 40 degree F, at what rate must heat he added to the interior air to keep it at 70 degree F? As a first approximation, neglect heat transfer through the ends. An aluminum wire 2.5 m long conducts 12 A with an imposed voltage of 1.5 V.
Explanation / Answer
The formula for rate of heat flow is ?Q/?t = -K
