In radiative calculations, what is the view factor of the surface of the outside of a pipe with itself? O 2.0 O 1.0 O 0.5 O 0.0
Q: Two infinitely long parallel plates of width w arelocated at a distance of w apart.Determine the…
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A: Hii, thanks for the question, We are authorized to answer one question at a time, since you have not…
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- 1.26 Repeat Problem 1.25 but assume that the surface of the storage vessel has an absorbance (equal to the emittance) of 0.1. Then determine the rate of evaporation of the liquid oxygen in kilograms per second and pounds per hour, assuming that convection can be neglected. The heat of vaporization of oxygen at –183°C is .Two large parallel plates with surface conditions approximating those of a blackbody are maintained at 816C and 260C, respectively. Determine the rate of heat transfer by radiation between the plates in W/m2 and the radiative heat transfer coefficient in W/m2K.1.28 The sun has a radius of and approximates a blackbody with a surface temperature of about 5800 K. Calculate the total rate of radiation from the sun and the emitted radiation flux per square meter of surface area.
- Determine the rate of radiant heat emission in watts per square meter from a blackbody at (a) 15C, (b) 600C, and (c) 5700C.11.31 A large slab of steel 0.1 m thick contains a 0.1 -m-di- ameter circular hole whose axis is normal to the surface. Considering the sides of the hole to be black, specify the rate of radiative heat loss from the hole. The plate is at 811 K, and the surroundings are at 300 K.11.68 Two infinitely large, black, plane surfaces are 0.3 m apart, and the space between them is filled by an isothermal gas mixture at 811 K and atmospheric pressure. The gas mixture consists of by volume. If one of the surfaces is maintained at 278 K and the other at 1390 K, calculate (a) the effective emissivity of the gas at its temperature, (b) the effective absorptivity of the gas to radiation from the 1390 K surface, (c) the effective absorptivity of the gas to radiation from the 278 K surface, and (d) the net rate of heat transfer to the gas per square meter of surface area.
- Determine the total average hemispherical emissivity and the emissive power of a surface that has a spectral hemispherical emissivity of 0.8 at wavelengths less than 1.5m, 0.6 at wavelengths from 1.5to2.5m, and 0.4 at wavelengths longer than 2.5m. The surface temperature is 1111 K.1.25 A spherical vessel, 0.3 m in diameter, is located in a large room whose walls are at 27°C (see sketch). If the vessel is used to store liquid oxygen at –183°C and both the surface of the storage vessel and the walls of the room are black, calculate the rate of heat transfer by radiation to the liquid oxygen in watts and in Btu/h.For the long (into the screen) triangular enclosure shown below, find the view factor from surface 1 to surface 3 (i.e. F13 ) L, =Lz (2) 45° L3= 3ft O 0.7071 O 0.75 0.5 O 0.668
- Earth absorbs solar energy and radiates infrared energy. The intensity of the solar radiation incident on earth is J = 1350 Wm-2, also known as the solar constant. Assume earth’s surface (ground) temperature to be uniform at Ts, and that the ground and atmosphere are black (emissivity = 1) for infrared radiation. The radius of the earth is 6.378 x 106 m. The diagram shows the ground at the surface temperature Ts and the atmosphere, represented as a thin black layer, at temperature Ta . Suppose the atmosphere absorbs 100% of the infrared radiation emitted by the ground. Assume that the ground absorbs 47.5% of the incident solar energy, and that the atmosphere absorbs 17.5% of the incident solar energy (for a total of 65% absorbed by the planet). Calculate the "steady state” numerical values of the earth’s ground temperature Ts and the atmospheric temperature Ta taking into account the “greenhouse effect” of atmospheric infrared absorption and emission described above.Imagine you have two concentric, coaxial cylindrical tubes with an evacuated annular space, with equal lengths L. The outer radius of the inner cylinder is r, and the inner radius of the outer cylinder is R. If we want to minimize the self-viewing factor of the inner surface of the outer cylinder, which of the following geometric changes would you suggest? r is fixed, decrease R with fixed R and L, decrease r with fixed r and R, decrease L R is fixed, increase L r is fixed, increase RPlease handwriting ok Part7. A spherical ball with a diameter of 10 cm has an outer surface that is maintained at a temperature of 200°C. It is suspended in the middle of a room that has an average temperature of 20°C. If the surface emissivity is 0.8, determine the rate of radiative heat transfer from the ball to the room in W. (Choose the nearest value) A. 2.3 W B. 4.5 W C. 19.4 W D. 60.8 W