Question 3 Determine the heat transfer through the composite wall shown in the figure 2 below. Take the thermal conductivities of P, Q, R, S & T as 60,15,7.67,25 & 35 W/mK respectively and assume one dimensional heat transfer. Take of area of P=S=T=1.5m and Q R = 0.75 m. Temperature entering at wall P is 850C and leaving at wall T is 115C. P Q R 12 1 Figure 2 T Question 4 (a) Briefly explain what is meant by "Fouling Factor" in heat exchangers. (b) In a food processing plant, a brine solution is heated from 7.5C to 14C in a double-pipe heat exchanger by water entering at 60C and leaving at 45C at the rate of 0.166 kg/s. If the overall heat transfer coefficient is 950 W/m.0 C, what heat exchanger area is required for a counter-flow case? Take Cp for water-4.180 kJ/kg. K. (23 Marks) Question 5 (a) In heat transfer by radiation, interpret what this equation represents: a + p + t = 1. (b) Radiation occurs between the floor, walls, and ceiling of a room with a floor area of 8 ft by 12 ft and a ceiling height of 8 ft as shown in figure 3. Given that the view factor F-2 0.11, then by using both the summation relation and principle of symmetry, find the remaining view factors: F-3, F1-4. F1-5, and F-6 respectively. -Ceiling (23 Marks) 1-end well 2-opposite end wall 3-foor 4-ceiling 5-side wall 8-side wall End wall Figure 3 Geometry of the room (23 Marks)