A hot surface at 250°C is to be cooled by attaching straight aluminum rectangular fins (k = 240 W/m K) with 25 mm length, 50 mm width and 4 mm base thickness. Fins are exposed to an ambient air condition of 30°C and heat transfer coefficient is 40 W/m2-K. If there are 2000 fins per m? surface area, calculate; a. The heat transfer rate from a single fin. b. The increase in the rate of heat transfer per m² surface area as a result of attaching 2000 fins. c. Determine the overall effectiveness of the fins.

A hot surface at 250°C is to be cooled by attaching straight aluminum rectangular fins (k = 240 W/m K) with 25 mm length, 50 mm width and 4 mm base thickness. Fins are exposed to an ambient air condition of 30°C and heat transfer coefficient is 40 W/m2-K. If there are 2000 fins per m? surface area, calculate; a. The heat transfer rate from a single fin. b. The increase in the rate of heat transfer per m² surface area as a result of attaching 2000 fins. c. Determine the overall effectiveness of the fins.

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.

Chapter1: Basic Modes Of Heat Transfer

Section: Chapter Questions

Problem 1.18P: The heat transfer coefficient for a gas flowing over a thin float plate 3-m long and 0.3-m wide...

See similar textbooks

Similar questions

1.1 On a cold winter day, the outer surface of a 0.2-m-thick concrete wall of a warehouse is exposed to temperature of –5°C, while the inner surface is kept at 20°C. The thermal conductivity of the concrete is 1.2 W/m K. Determine the heat loss through the wall, which is 10-m long and 3-m high. Problem 1.1
3.10 A spherical shell satellite (3-m-OD, 1.25-cm-thick stainless steel walls) re-enters the atmosphere from outer space. If its original temperature is 38°C, the effective average temperature of the atmosphere is 1093°C, and the effective heat transfer coefficient is , estimate the temperature of the shell after reentry, assuming the time of reentry is 10 min and the interior of the shell is evacuated.
The air-conditioning system in a Chevrolet van for use in desert climates is to be sized. The system is to maintain an interior temperature of 20C when the van travels at 100 km/h through dry air at 30C at night. If the top of the van is idealized as a flat plate 6 m long and 2 m wide and the sides as flat plates 3 m tall and 6 m long, estimate the rate at which heat must be removed from the interior to maintain the specified
The heat transfer coefficient for a gas flowing over a thin float plate 3-m long and 0.3-m wide varies with distance from the leading edge according to hc(x)=10x1/4Wm2K If the plate temperature is 170C and the gas temperature is 30C, calculate (a) the average heat transfer coefficient, (b) the rate of heat transfer between the plate and the gas, and (c) the local heat flux 2 m from the leading edge. Problem 1.18
A hot surface at 350°C is to be cooled by attaching straight aluminum rectangular fins (k-250 W/m K) with 35 mm length, 70 mm width and 5 mm base thickness. Fins are exposed to an ambient air condition of 28°C and heat transfer coefficient is 35 W/m² K. If there are 1750 fins per m² surface area, calculate; a. The heat transfer rate from a single fin. b. The increase in the rate of heat transfer per m² surface area as a result of attaching 1750 fins. c. Determine the overall effectiveness of the fins.
Finned heat sinks are used to keep computer chips in an acceptable temperature range. The heat sink base is 53 mm x 57 mm, and the maximum allowable chip temperature is 75 C. An array of 54 aluminum fins (k = 237 W/m*K) which have a square cross-section (3 mm x 3 mm) are attached to the heat sink. The length of each fin is 30 mm. The cooling air supplied to the heat sink is 25 C. If the convection heat transfer coefficient is 125 W/m2*K, what is the heat transfer rate (in W) from the heat sink, assuming adiabatic fin tips? (Hint: heat transfer does not solely occur from the fins.)
Consider a closed cylindrical reactor vessel of diameter D= 1 ft, and length L= 1.5 ft. The surface temperature of the vessel, T1, and the surrounding temperature, T2, are 390 deg. F and 50 deg. F, respectively. The convective heat transfer coefficient, h, between the vessel wall and surrounding fluid is 4.0 Btu/h . ft . ⁰F. Calculate the thermal resistance in ⁰F .h/Btu.
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.
A 1 m long, 5 cm diameter, cylinder placed in an atmosphere of 40°C is provided with 12 longitudinal straight fins (k = 75 W/m.K), 0.75 mm thick. The fins protrudes 2.5 cm from the cylinder surface. The heat transfer coefficient is 23.3 W/m^2.K.W/m2.K. Calculate the rate of heat transfer and fin efficiency, if the surface temperature of cylinder is at 150°C.
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?
In the design of electronic components, it is very desirable to attach the electronic circuitry to a substrate material that is a very good thermal conductor but also a very effective electrical insulator. If the high cost is not a major concern, what material would you propose for the substrate?
15. The wall of a building consists of a 360-mm thick layer A which has a thermal conductivity, kA - 4.9 W/m-K, followed by a 80-mm thick second layer, layer B, which has a thermal conductivity, kg = 0.9 W/m-K. The inside and outside convection coefficients are 20 W/m² K and 39 W/m2 K. At these conditions, what is the overall heat transfer coefficient for this composite wall? Express your answer in W/m^2 K.