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A shell-and-tube heat exchanger is used to heat a liquid that flows in tubes of inside and outside diameters Di = 10 mm and Do = 11mm. You have been

asked to choose the most cost-efficient material for the tubes. Material A has a density pA = 8900 kg/m³ and a thermal conductivity k A = 5 W/m-K. Material B has a density pB= 1780 kg/m3 and a thermal conductivity k B = 0.17 W/m-K The cost of material A per unit mass is three times the cost of material B. Determine which is most cost-efficient by: a) Calculating the ratio of material B to material A surface area needed for the same heat transfer rate. b) Determining the ratio of the mass of material B to material A. c) Finding the cost ratio of the mass of material B to material A. The inner and outer heat transfer coefficients are hi = 1000 W/m2-Kand ho = 200 W/m2-K, respectively. Find the inside convective resistance, in K-m/W. Find the outside convective resistance, in K-m/W. Find the conductive resistance of material A, in K-m/W. Find the conductive resistance of material B, in K-m/W. The parts of this question must be completed in order. This part will be available when you complete the part above. The parts of this question must be completed in order. This part will be available when you complete the part above.

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