The free convection heat transfer coefficient on a thin hot vertical plate suspended in still air can be determined from observations of the change in plate temperature with time as it cools. Assuming the plate is isothermal and radiation exchange with its surroundings is negligible, evaluate the convection coefficient, in W/m².K, at the instant of time when the plate temperature is 245°C and the change in plate temperature with time (dT/dt) is -0.028 K/s. The ambient air temperature is 25°C and the plate measures 0.325 x 0.325 m with a mass of 4.25 kg and a specific heat of 2770 J/kg-K. h = W/m².K

The free convection heat transfer coefficient on a thin hot vertical plate suspended in still air can be determined from observations of the change in plate temperature with time as it cools. Assuming the plate is isothermal and radiation exchange with its surroundings is negligible, evaluate the convection coefficient, in W/m².K, at the instant of time when the plate temperature is 245°C and the change in plate temperature with time (dT/dt) is -0.028 K/s. The ambient air temperature is 25°C and the plate measures 0.325 x 0.325 m with a mass of 4.25 kg and a specific heat of 2770 J/kg-K. h = W/m².K

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 1.19P: 1.19 A cryogenic fluid is stored in a 0.3-m-diameter spherical container is still air. If the...

See similar textbooks

Similar questions

The heat transfer rate from hot air by convection at 100C flowing over one side of a flat plate with dimensions 0.1m0.5m is determined to be 125 W when the surface of the plate is kept at 30C. What is the average convection heat transfer coefficient between the plate and the air?
A pipe carrying superheated steam in a basement at 10C has a surface temperature of 150C. Heat loss from the pipe occurs by radiation (=0.6) and natural convection (hc=25W/m2K). Determine the percentage of the total heat loss by these two mechanisms.
1.29 A spherical interplanetary probe with a 30-cm diameter contains electronic equipment that dissipates 100 W. If the probe surface has an emissivity of 0.8, what is its surface temperature in outer space? State your assumptions in the calculations.
1.79 Consider the cooling of (a) a personal computer with a separate CPU and (b) a laptop computer. The reliable functioning of these machines depends on their effective cooling. Identify and briefly explain all modes of heat transfer involved in the cooling process.
A copper plate, with dimensions of 3 cm x 3 cm x5 cm (length, width, and thickness, respectively), isexposed to a thermal energy source that puts out 150 J every second, as shown in the accompanyingfigure. The density of copper is 8900 kg/m3. Assuming no heat loss to the surrounding block, determinethe temperature rise in the plate after 10 seconds.
700 W/m3 electrical heat is generated in a large plane wall whose one side is insulated while the other side is subjected to convection. The thermal conductivity of the wall is (k W/m.K) and the convection heat transfer coefficient is (h = 17 W/m?K). Determine the location and the value for the maximum temperature and the minimum temperature in the plate for steady one-dimensional heat transfer. Assume T. = 25°C. A=1 m?; L= 25 cm). = 20
The Biot number during a heat transfer process between a sphere and its surroundings is determined to be 0.02. Would you use lumped system analysis or the transient temperature charts when determining the midpoint temperature of the sphere? Why?
1-72 A 5-cm-external-diameter, 10-m-long hot-water pipe at 80°C is losing heat to the surrounding air at 5°C by natu- ral convection with a heat transfer coefficient of 25 W/m²-K. Determine the rate of heat loss from the pipe by natural con- vection. Answer: 2945 W
Air at 20°C with a convection heat transfer coefficient of 25 W/m2-K blows over a horizontal steel hot plate (k = 43 W/m-K). The surface area of the plate is 0.38 m2 with a thickness of 2 cm. The plate surface is maintained at a constant temperature of Ts = 250°C and the plate loses 300 W from its surface by radiation. Calculate the inside plate temperature (Ti). FIGURE P1-96 Air, 20°C T, = 250°C Steel Plate T; = ?
q1
heat transfer question
Required information A 14-cm x 20-cm circuit board houses on its surface 100 closely spaced logic chips, each dissipating 0.06 W in the environmentat 40°C. The heat transfer from the back surface of the board is negligible. If the heat transfer coefficient on the surface of the board is 10 W/m2.K, Determire the surface temperature of the chips in °C. (Round the final answer to two decimal places.