Analyze the effectiveness of a heat exchanger intended to heat water with the flue gas from a combustion chamber as shown in the schematic diagram. The water is flowing through a finned tube, having dimensions shown in the schematic diagram, at a rate of 0.17 kg/s, while the flue gases are flowing through the annulus in the flow channels between the fins at a velocity of 10 m/s. The finned tubes may be constructed from carbon steel or copper. Determine the rate of heat transfer per unit length of tube from the gas to water at a water temperature of 200 K and a flue gas temperature of 700 K. Based on a cost analysis comparing copper and steel, recommend the appropriate material to be used for this device.

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Do = 60 mm Di2 = 30 mm Gas Water Gas t = 3 mm D₁ = 24 mm