A single-glazed glass window pane is an arched shape, consisting of a semicircle of radius 0.5 m on top of a rectangle 1.0 m wide by 2.0 m high, with no joints. The glass pane is 5 mm thick. One side of the window is exposed to air at 20°C and the other side is exposed to air at 5°C. Assuming convective heat transfer on both sides of the window, and conduction through it, determine the total thermal resistance of the window pane and hence the rate of heat transfer through it. (Convection: h= 15 W/m²K; Glass: k = 1.1 W/mK)

Heat transfer

A composite wall is made of a layer of material A sandwiched between two layers of material B. The inner and outer surface temperatures are 25 and 10oC, respectively. Calculate heat flow in W/m2 through the wall. Take k values for A and B as 0.04 and 0.10 W/m K, respectively. The thickness of A is 5 cm, and that of B is 2 cm, respectively.

An insulated steam pipe is routed horizontally through an unheated room, then vertically to the ceiling. The pipe is insulated, and the outside diameter of the insulation is 15 cm. The horizontal and vertical lengths of pipe are both 4 m long. The outside-surface temperature of the insulation is 50°C, and the room temperature is 5°C. How much heat is lost from the insulation by convection?