Q5. A 12m long and 5m high wall is constructed of two layers of 1cm thick sheetrock (k=0.17W/m.C) spaced 16cm by wood studs (k=0.11W/m.C) whose cross section is 16cm5cm. The studs are placed vertically 60cm apart, and the space between them is filled with fiberglass insulation (k=0.034 W/m.C ). The house is maintained at 20C and the ambient temperature outside is 9C. Taking the heat transfer coefficients at the inner and outer surfaces of the house to be 8.3 and 34W/m2. CC respectively, determine (a) The thermal resistance of the wall considering a representative section of it (b) The rate of heat transfer through the wall Q6. Superheated steam at an average temperature 200C is transported through a steel pipe (k=50W/m.C,D0=8cm,Di=6cm and L=20m). The pipe is insulated with a 4cm thick layer of gypsum plaster (k=0.5W/m. C). The insulated pipe is placed horizontally inside a warehouse where an average air temperature is 10C. The steam and the air heat transfer coefficients are estimated to be 800 and 200W/m2.C respectively. Calculate (a) The daily rate of heat transfer from the superheated steam (b) The temperature on the outside surface of the gypsum plaster insulation. Q7. A 2.2mm diameter and 10m long electric wire is tightly wrapped with a 1mm thick plastic cover whose thermal conductivity is k=0.15W/m.C. Electrical measurements indicate that a current of 13A passes through the wire and there is a voltage drop of 8V along the wire. If the insulated wire is exposed to a medium at Tm=30C with a heat transfer coefricient of h=24W/mC, determine the temperature at the interface of the wire and the plastic cover in steady operation. Also determine if doubling the thickness of the plastic cover will increase or decrease this interface temperature