A 1 m x 1.25 m hot surface at 300°C is to be cooled by attaching a rectangular fins (k = 200 W/m-K) with 30 mm length, 75 mm width and 5 mm base thickness. Fins are exposed to an ambient air condition of 25°C and heat transfer coefficient is 30 W/m K. If there are 2250 fins, calculate; a. The heat transfer rate from a single fin. b. The increase in the rate of heat transfer. c. Determine the overall effectiveness of the fins. с.

A 1 m x 1.25 m hot surface at 300°C is to be cooled by attaching a rectangular fins (k = 200 W/m-K) with 30 mm length, 75 mm width and 5 mm base thickness. Fins are exposed to an ambient air condition of 25°C and heat transfer coefficient is 30 W/m K. If there are 2250 fins, calculate; a. The heat transfer rate from a single fin. b. The increase in the rate of heat transfer. c. Determine the overall effectiveness of the fins. с.

Principles of Heat Transfer (Activate Learning with these NEW titles from Engineering!)

8th Edition

ISBN:9781305387102

Author:Kreith, Frank; Manglik, Raj M.

Publisher:Kreith, Frank; Manglik, Raj M.

Chapter6: Forced Convection Over Exterior Surfaces

Section: Chapter Questions

Problem 6.13P

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One hundred circumferential aluminum fins of rectangular profile are mounted on a 1.0-m tube having a diameter of 2.5 cm. The fins are 1 cm long and 2.0 mm thick. The base temperature is 180°C, and the convection environment is at 20°C with h=50 W/m2· °C. Calculate the total heat lost from the finned-tube arrangement over the 1.0-m length.
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J 5 A cylindrical steel tank with a diameter of 1.8m and a height of 2m, is insulated with polyurethane on its lateral faces and its lid. The insulation is 40 mm thick and covered with a thin layer of metal. The tank contains water that is kept warm by an electric heater in such a way as to maintain the inner surface of the tank at a temperature of 55C. The ambient air temperature is 10C and the external skin coefficient is 10 w/m2K. If the energy cost is $0.15/kwh. What is the monthly energy cost for water storage?
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