An insulated steam pipe located where the ambient temperature is 32°C, has an inside diameter of 50 mm with 10 mm thick wall. The outside diameter of the corrugated asbestos insulation is 125 mm and the surface coefficient of still air, h0 = 12 W/m2 -K. Inside the pipe is steam having a temperature of 150°C with film coefficient hi = 6000 W/m2 . Thermal conductivity of pipe and asbestos insulation are 45 and 0.12 W/m-K respectively. Determine the heat loss per unit length of pipe.

A 10 cm-thick beef steak is being frozen in a -40°C room. The product has 73% moisture content, density of 970 kg/m³, and thermal conductivity (frozen) of 1.1 W/(m K). Estimate the freezing time using Plank’s equation. The product has an initial freezing temperature of  -1.75°C, and the movement of air in the freezing room provides a convective heat-transfer coefficient of 10 W/(m² K). a. tf =... h

The main body of plenum is a steel vessel of diameter 0.1meters has two semicircle domed ends. During operation is will contain mix of fuel and air at approximately 250OC. The wall of the vessel is 0.03meters thick and the plenum is 0.45meters long. Estimate the rate of heat loss from the vessel when the outside air temperature is 45OC. The thermal conductivity of steel is 45 W/m K and the surface heat transfer coefficient on the air side is 8 W/m2 . On the inside it is 65W/m2 . If it was possible to clad the plenum calculate the reduction in the rate of heat loss. Assume the lagging would be 5mm thick and has a thermal conductivity of 0.05 W/m.