: 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 0.7 for solar radiation. If solar radiation is incident on the plate at a rate of 700 W/m2 and the surrounding air temperature is 10°C, determine the surface temperature of the plate when the heat loss by convection equals the solar energy absorbed by the plate. Take the convection heat transfer coefficient to be 30 W/m2 - °C, and disregard any heat loss by radiation.

: 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 0.7 for solar radiation. If solar radiation is incident on the plate at a rate of 700 W/m2 and the surrounding air temperature is 10°C, determine the surface temperature of the plate when the heat loss by convection equals the solar energy absorbed by the plate. Take the convection heat transfer coefficient to be 30 W/m2 - °C, and disregard any heat loss by radiation.

Elements Of Electromagnetics

7th Edition

ISBN:9780190698614

Author:Sadiku, Matthew N. O.

Publisher:Sadiku, Matthew N. O.

ChapterMA: Math Assessment

Section: Chapter Questions

Problem 1.1MA

See similar textbooks

Similar questions

The horizontal roof of a building has an emittance of 0.9. Air temperature is 1oC on a clear night. Sky acts as a black radiation sink at -60o If the underside of the roof is well insulated, estimate the roof temperature. Assume a convective heat transfer coefficient of 5 W/m2 K.
A pipe is carrying cold water. At a small section of the pipe it was found that the average water temperature is 5°C and its convection coefficient is 20 W/m².K. The pipe is exposed to air outside at 30°C. The air's convection coefficient is 12 W/m².K. The pipe is made of a material whose thermal conductivity of 2 W/m.K. The inner radius of the pipe is 10 cm. The thickness of the pipe is 4 cm. Draw an appropriate schematic with appropriate labels and coordinate system. Write the governing equation and the boundary conditions for finding out the temperature distribution in the pipe material. Find out the outer surface temperature of the pipe.
A 5-mm-diameter spherical ball at 50 oC is covered by a 1-mm-thick plastic insulation (k=0.13 W/m.oC). The ball is exposed to a medium at 15 oC, with a combined convection and radiation heat transfer coefficient of 20 W/m2.oC. Determine if the plastic insulation on the ball will help or hurt heat transfer from the ball.
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) =
An asphalt playground is heated in the sun all day; by sundown it reaches a temperature of 45degC. If the asphalt has an emissivity of 0.8, what is the heat flux emitted off the asphalt at night?
Required information Consider an aluminum pan used to cook stew on top of an electric range. The bottom section of the pan is 0.25 cm thick and has a diameter of 14 cm. The electric heating unit on the range top consumes 900 W of power during cooking, and 90 percent of the heat generated in the heating element is transferred to the pan. During steady operation, the temperature of the nner surface of the pan is measured to be 108°C. Determine the heat flux at the bottom of the pan (up to 1 decimal place). The heat flux at the bottom of the pan = |kW/m2 %3D 27 ^ D a ENG 11/1C 18°C Clear
Consider a person standing in a room kept at 22°C at all times. It was observed that the interior surfaces of the walls, floor and ceiling of the house were at an average temperature of 15°C. If the exposed surface area of this person is 1.4 m^2 and the average external surface temperature is 30°C, determine the rate of radiation and heat transfer between this person and the surrounding surfaces. The spread of the person Ɛ=0.95 Stefan-Boltzmann constant σ=5.67X10^-8 W/m^2K^4
The solar radiation incident on the outside surface of an aluminum shading device is 1300 W/m2. Aluminum absorbs 10% of the incident solar energy, and dissipates it by convection from the back surface and by combined convection and radiation from the outside surface. The convection heat transfer coefficient is 10 W/m2·K for both surfaces, and the ambient/surrounding temperature can be taken 20 °C for both convection and radiation. Assuming that the aluminum shade has a uniform temperature, determine the temperature of the aluminum shading device if it is a) Polished, and b) Oxidized.
In a textile unit, hot fluid flows through a long steel pipe (k=15 W/m°C) with inner and outer diameters of 70 mm and 75 mm, respectively. The convection coefficient between the hot fluid and the inner surface of the pipe is 100 W/m²K, the convection coefficient between the outer surface of the pipe and the ambient air is 10 W/m²K, and the emissivity (emission) coefficient of the pipe is 0,75. Under steady regime conditions; Since the pipe outer surface temperature is 80°C, the outside air and ambient temperature is 20°C,a) The total amount of heat lost to the environment per unit length of the pipe,b) Calculate the hot fluid temperature and the pipe inner surface temperature.
A thin electric heater is inserted between a long circular rod and a concentric tube with inner and outer radii of 20 and 40 mm, respectively. The steel rod (A) has a thermal conductivity of KA = 15 W/m.K and the plastic tube (B) has a thermal conductivity of kB = 0.8 W/m.K. The outer surface of the tube is subjected to convection with a fluid at a temperature of T = -5°C and heat transfer coefficient of 50 W/m²K. The thermal contact resistance between the cyl- inder surfaces and the heater is negligible. (40 points) (a) Determine the electrical power per unit length (W/m) that is required to maintain the outer surface of cylinder B at 5°C for steady state conditions. (b) Based on part (a), what is the steady state temperature at the center of cylinder A? (c) If the heater is turned off, estimate the time for the steel rod to drop 15°C. Assume steel has a density of p= 7900 kg/m³ and specific heat of c = 400 J/kg.K. Thin electric heater Too, h TA TB A tube B rod
A thermocouple shielded by a layer of aluminum foil and copper with an emissivity of 0.05 and 0.02 is used to measure the temperature of hot gases flowing in a duct whose walls are maintained at T= 380K. Assuming emissivity of the thermocouple junction is 0.7 and convection heat transfer coefficient to be h= 130 W/m2.C, determine the radiation heat transfer from thermocouple junction to duct wall.
Explain the following terms related to the radiation mode of heat transfer: Black body, emissive power, monochromatic emissive power, gray body, white body and opaque body.