The outer surface of a spacecraft in space has emissivity of 0.8 and a solar absorptivity of 0.3. If solar radiation in incident on the spacecraft at a rate of 950 W/m^2, determine the surface temp of the spacecraft when the radiation emitted equals the solar energy absorbed.

At midday when a black paved airport runway is directly under the Sun, it receives 800 W of solar power per square meter of surface from the Sun. If this hot surface loses energy only by radiation back into the atmosphere, what is its equilibrium temperature (in K)? You may use an emissivity of e = 1 for a black surface

Determine the amount of acres of land necessary to generate 50 MW of solar power at noon in Philadelphia with an array of panels positioned horizontally. Assume that the panels are 21 % efficient and that the solar irradiation at noon is 900 W/m².

A black body absorbs radiant energy at the rate of 5 kW/m2 . Calculate the temperature at which the rate of radiant heat transfer will be zero.

A thin square steel plate, 10 cm on the side, is heated in a blacksmiths forge to a temperature of 800°C. if the emissivity is 0.60, what is the total rate of radiation of energy in Watts?

Given the following information for two windows in a room, one placed on the south side, and the other on the north side, calculate the solar heat gain passing through each window. What do you suggest to increase the solar heat gain through windows? South window North window Area 2 m² 2 m² U-value 1.5 W/m.K 1.5 W/m.K SHGC 0.45 0.35 Isolar (for one day) 4200 Wh/m² 350 Wh/m²

Determine the amount of acres of land necessary to generate 50 MW of solar power at noon in Philadelphia with an array of panels positioned horizontally. Assume that the panels are 21 % efficient and that the solar irradiation at noon is 900 W/m?

A cylindrical tube has an inner diameter of 2 cm and a wall thickness of 1 cm. The tube is evacuated. In the center, there is a radiation source along its axis that sends 1e^5 W/m^2 to the inner surface of the tube. K for the tube wall is 2 W/m K. If the outer surface of the tube is cooled with water at 298 K with a convective heat transfer coefficient of 100 W/m^2 K, determine the minimum temperature rating for the tube material for safe operation.

Determine the heat transfer that occurs by radiation between two surfaces that are co-axial and parallel to each other, full and semicircular. Assume that the surfaces only exchange radiation with each other. T1 = 700 °C; ɛ1 = 0.8; T2 = 20 °C; e2 = 0.4. фб ст (2) to 4 cm 6 8 cm (1 t.

question from zemansky book