cen58933_ch10

# 1037c what is the modified latent heat of

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Unformatted text preview: ined at 90°C by circulating cooling water through the other side. Determine (a) the rate of heat transfer by condensation to the plate, and (b) the rate at which the condensate drips off the plate at the bottom. Answers: (a) 942 kW, (b) 0.412 kg/s 1 atm Steam 5m Condensation Heat Transfer 10–34C What is condensation? How does it occur? 10–35C What is the difference between film and dropwise condensation? Which is a more effective mechanism of heat transfer? 90°C 3m 10–36C In condensate flow, how is the wetted perimeter defined? How does wetted perimeter differ from ordinary perimeter? 10–37C What is the modified latent heat of vaporization? For what is it used? How does it differ from the ordinary latent heat of vaporization? · m FIGURE P10–44 10–38C Consider film condensation on a vertical plate. Will the heat flux be higher at the top or at the bottom of the plate? Why? 10–45 Repeat Problem 10–44 for the case of the plate being tilted 60° from the vertical. 10–39C Consider film condensation on the outer surfaces of a tube whose length is 10 times its diameter. For which orientation of the tube will the heat transfer rate be the highest: horizontal or vertical? Explain. Disregard the base and top surfaces of the tube. 10–46 Saturated steam at 30°C condenses on the outside of a 4-cm-outer-diameter, 2-m-long vertical tube. The temperature of the tube is maintained at 20°C by the cooling water. Determine (a) the rate of heat transfer from the steam to the cooling water, (b) the rate of condensation of steam, and (c) the approximate thickness of the liquid film at the bottom of the tube. 10–40C Consider film condensation on the outer surfaces of four long tubes. For which orientation of the tubes will the condensation heat transfer coefficient be the highest: (a) vertical, (b) horizontal side by side, (c) horizontal but in a vertical tier (directly on top of each other), or (d) a horizontal stack of two tubes high and two tubes wide? 10–41C How does the presence of a noncondensable gas in a vapor influence the con...
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