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Unformatted text preview: 3. Water enters a 2.5 cm internal diameter thin copper tube of a heat exchanger at 15 o C at a rate of 0.3 kg/s, and is heated by steam condensing outside at 120 o C. If the average heat transfer coefficient is 800 W/m 2-C, what is the length of the tube required in order to heat the water to 115 o C. 4. Consider the flow of oil at 20 o C in a 30-cm-diameter pipeline at an average velocity of 2 m/s. A 200-m long section of the pipeline passes through icy waters of a lake at 0 o C. Measurements indicate that the surface temperature of the pipe is 0 o C. Disregarding the thermal resistance of the pipe material, find: a) the temperature of the oil when the pipe leaves the lake b) the rate of heat transfer from the oil c) the pumping power required to overcome the pressure losses...
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