2. (20 points) A certain surface maintained at 1400 K has the following spectral emissive characteristics:...
PROBLEM 2-Emissivity A wall is at 300K and 600K. It has the following spectral emissivity in the long wavelength end of the thermal radiation spectrum: <10 μm = 0.0 10 μm to 100 μm > 100 μm 0.0 0.35 Calculate the total emissivity and emissive power at the specified temperatures. Does the total emissivity increase or decrease at the higher temperature?
Problem 3 (10 points) For a blackbody at 2250 K that is in air, find: (b) the hemispherical total emissive power (kW Im2). (c) the emissive power in the spectral range between o 2 and 8um. (d) the ratio of spectral intensity at no-2 μm to that at no-8 μm.
Problem 3 (10 points) For a blackbody at 2250 K that is in air, find: (b) the hemispherical total emissive power (kW Im2). (c) the emissive power in the spectral...
(a) Schematically draw the spectral emissive power of two blackbodies with the temperature of 2400 K and 300 K (ie. EBA versus λ). What are the wavelengths at the maximum spectral emissive power? (5 pts) (b) A thin-walled plate separates the interior of a large furnace from surroundings at 300 K. The plate is fabricated from a ceramic material for which diffuse surface behavior may be assumed and the exterior surface is air-cooled. With the furnace operating at 2400 K...
Measurement of the spectral, directional absorptivity of a
certain non-reflecting surface shows that directional and spectral
dependencies may be model as the product of two independent
functions:
This surface is irradiated by diffuse blackbody radiation at a
temperature of 5800 K. Note that the intensity of ideal radiation
can be calculated at Ib=
Eb/pi(W/m2 -sr). The surface is at a uniform
temperature of 300 K.
Determine the rate that energy is absorbed by the surface
(W/m2 )
Determine the net...
Problem 3 (15 points) A white ceramic surface has a hemispherical spectral emissivity distribution at 1600 K as shown. What is the hemispherical total emissivity of the surface at this surface temperature? My guess is you need to do a numerical integration here. 1.0 0.8 0.6 E N 0.4 0.2 10 10 2 4 6 8 10 12 λ, μ
Problem 3 (15 points) A white ceramic surface has a hemispherical spectral emissivity distribution at 1600 K as shown. What...
7. The spectral emissivity of an opaque surface at 2000 K is approximated as: EX -0.3, for OS <3um -0.8, for 3um SX < 6um -0.4, for hum S. < 0 Determine: a) The total emissivity of the surface,
1.0 A diffuse surface at T = (9400) K. has the spectral, hemispherical emissivity illustrated. Determine the following: E2 0.8 2. = 2 um 12 = 5 um a. the total, hemispherical emissivity is ε = (+0.001) E, () E1 0.4 b. the total emissive power is E = kW/m² (+0.1%) 0 2 5 (um)
1.0 A diffuse surface at T = (2200) K. has the spectral, hemispherical emissivity illustrated. Determine the following: 0.8 21 = 2 pm 12 = 5 um a. the total, hemispherical emissivity is ε = (+0.001) E, () E1 0.4 b. the total emissive power is E = kW/m² (+ 0.1%) 0 2 5 (um)
A small object with an opaque, diffuse surface at a temperature
of 500 K is suspended in a large furnace with walls at 2000 K.
Assume that the walls of the furnace provide a diffuse irradiation
to the object at a blackbody temperature equal to the furnace wall
temperature. The object’s surface has a spectral hemispherical
emissivity and absorptivity as given below. (a) Determine the total
emissivity and total absorptivity of the object’s surface. Partial
Ans: ?=0.021 (b) Evaluate the...
For a given material at 3000 K, the transmissivity and reflectivity are as follows, O um< <0.4 um: p=0.4 and t=0.5 0.4 um< <0.6 um: p=0.3 and 1 = 0.2 î>0.7 um: p=0.1 and 1=0.7. a) Make a plot of the emissivity of the material. Assume Kirchoff's law holds. You should have wavelength on the x axis and ε on the y axis. b) Calculate the average emissivity of the material.