A one-shell pass and one-tube pass shell-and-tube heat exchanger is to be designed to condense down the petroleum-based organic vapor available at a flow rate of 5kg/s and at a saturation tempenature of 75.6. The cold water (c7=4187J/kggK) used for its condensation is supplicd at a rate of 25kg/k and a temperanire of 15 "C. The cold-water flows through copper tubes with an outside diameter of 20mm, a thekness of 2 mm, and a length of 5m. The overall heat transfer coefficient is assumed to be 550W/m2, K and the latent heat of vaporization of the organic vapor may be taken to be 580kJ/kg. Assuming negliggble thermal tesistance due to pipe wall thickness, determine the number of tubes required