A thin metal plate is insulated on the back and exposed to solar radiation on the front surface. The exposed surface of the plate has an absorptivity of 0.8 for solar radiation. If solar radiation is incident on the plate at a rate of 450 W/m2 and the surrounding air temperature is 25°C, determine the surface temperature of the plate when the heat loss by convection equals the solar energy absorbed by the plate. Assume the convection heat transfer coefficient to be 85 W/m2*C, and disregard heat loss by radiation. 450 W -=DE 25C

A thin metal plate is insulated on the back and exposed to solar radiation on the front surface. The exposed surface of the plate has an absorptivity of 0.8 for solar radiation. If solar radiation is incident on the plate at a rate of 450 W/m2 and the surrounding air temperature is 25°C, determine the surface temperature of the plate when the heat loss by convection equals the solar energy absorbed by the plate. Assume the convection heat transfer coefficient to be 85 W/m2*C, and disregard heat loss by radiation. 450 W -=DE 25C

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...

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1.19 A cryogenic fluid is stored in a 0.3-m-diameter spherical container is still air. If the convection heat transfer coefficient between the outer surface of the container and the air is 6.8 , the temperature of the air is 27°C, and the temperature of the surface of the sphere is –183°C, determine the rate of heat transfer by convection.
A cooling system is to be designed for a food storage warehouse for keeping perishable foods cool prior to transportation to grocery stores. The warehouse has an effective surface area of 1860 m2 exposed to an ambient air temperature of 32C. The warehouse wall insulation (k=0.17W/(mK)) is 7.5 cm thick. Determine the rate at which heat must be removed (W) from the warehouse to maintain the food at 4C.
Heat is transferred at a rate of 0.1 kW through glass wool insulation (density=100kg/m3) with a 5-cm thickness and 2-m2 area. If the hot surface is at 70C, determine the temperature of the cooler surface.
2.55 A long, 1-cm-diameter electric copper cable is embedded in the center of a 25-cm-square concrete block. If the outside temperature of the concrete is 25oC and the rate of electrical energy dissipation in the cable is 150 W per meter length, determine temperatures at the outer surface and at the center of the cable.
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.
A flat plate has one surface insulated and the other exposed to the sun. The exposed surface absorbs solar radiation at a rate of 700 W/m2 and dissipates heat to the surrounding air at 350K. If the emissivity of the surface is 0.9 and the surface heat transfer coefficient is 10 W/m2.K, determine the surface temperature of the plate.
7- Consider a person standing in a room maintained at 20°C at all times. The inner surfaces of the walls, floors, and ceiling of the house are observed to be at an average temperature of 12°C in winter and 23°C in summer. Determine the rates of radiation heat transfer between this person and the surrounding surfaces in both summer and winter if the exposed surface area, emissivity, and the average outer surface temperature of the person are 1.6 m2, 0.95, and 32°C, respectively.
Consider a person standing in a room kept at 22°C at all times. Your house It has been observed that the inner surfaces of the walls, floor and ceiling are at an average temperature of 15°C. If this person's exposed surface area is 1.4 m2 and if the average external surface temperature is 30°C, this person and the surrounding surfaces Determine the radiation and heat transfer rate between One's emissivity, the Stefan-Boltzmann constant a=5,67x10 -8 W/m 2 K 4
A 1000-W iron is left on the iron board with its base exposed to the air at 20°C. The convection heat transfer coefficient between the base surface and the surrounding air is 35 W/m2. C. If the base has an emissivity of 0.6 and a surface area of 0.02 m2, determine the temperature of the base of the iron.
Determine the net heat transferred by radiation from a 9-ft square hot plate to a cold plate of equal size that are parallel to one another, and 20 ft apart if the hot plate is oxidized steel at 700°F and the cold plate is dull brass at 175°F.Ans: 2,863 Btu/hr
Consider a person standing in a room maintained at 20°C at all times. The inner surfaces of the walls, floors, and the ceiling of the house are observed to be at an average temperature of 15°C in winter and 30°C in summer. Determine the rate of radiation heat transfer between this person and the surrounding surfaces if the exposed surface area and the average outer surface temperature of the person are 1.2 m2 and 34°C, respectively. Given: εskin = 0.95, σ = 5.67x10^(-8) W/(m^2∙K^4 ). Heat Radiation in Winter (W) = Heat Radiation in Summer (W) =
Consider the rate of heat conduction through a double-paned window that has a 1.6-m2 area and is made of two panes of 0.76-cm-thick glass separated by a 0.75-cm air gap. You can ignore the increased heat transfer in the air gap due to convection. a. Calculate the rate of heat conduction through this window, in watts, given that the inside surface temperature is 15.0°C, while the outside temperature is -10.0°C. Make the assumption that the temperature differences across the two glass planes are equal. First find these and then the temperature drop across the air gap. b. For comparison, calculate the rate of heat conduction, in watts, through a single 1.67-cm-thick window of the same area and with the same temperatures as in part (a).