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2 (a) Two heat exchangers have the same design but one is arranged in counter flow and the other in parallel flow. Explain which arrangement is better for heat transfer if both heat exchangers have identical flows, flow rates and inlet temperatures. State any assumptions made. (3) (b) A 6 m long section of 8 cm diameter horizontal hot-water pipe passes through a large room whose temperature is 20°C. If the outer surface temperature of the pipe is 70°C: (1) Determine the rate of heat loss per unit length from the pipe by natural convection (12) (11) In order to reduce the rate of heat transfer, it has been proposed to arrange the same pipe vertically. Will this configuration work? Explain your answer. (10)