Write legibly, provide given, manual step by step solution, and diagram for below problem. The filament of a 100-watt bulb maybe considered a black body radiating into a black enclosure at 80 deg C. Considering only radiation, calculate the filament temperature in deg C if the filament is 0.10mm and the length is 6cm. A. 2514 B. 2837 C. 3122 D. 2674

Write legibly, provide given, manual step by step solution, and diagram for below problem. The filament of a 100-watt bulb maybe considered a black body radiating into a black enclosure at 80 deg C. Considering only radiation, calculate the filament temperature in deg C if the filament is 0.10mm and the length is 6cm. A. 2514 B. 2837 C. 3122 D. 2674

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.

Chapter11: Heat Transfer By Radiation

Section: Chapter Questions

Problem 11.11P

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1.54 The soldering iron tip in Problem 1.53 becomes oxidized with age and its gray-body emittance increases to 0.8. Assuming that the surroundings are at 20°C, determine the power requirement for the soldering iron.
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.
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 .
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.
4. The filament of a 75 W light bulb may be considered as a black body radiating into a black enclosure at 70° C. the filament diameter is 0.10 mm and length is 5 em. considering the radiation, determine the filament temperature .
The tungsten filament of an incandescent light bulb has a temperature of approximately 3000 K. The emissivity of tungsten is approximately 1/3, and you may assume that it is independent of wavelength. To increase the efficiency of an incandescent bulb, would you want to raise or lower the temperature? (Some incandescent bulbs do attain slightly higher efficiency by using a different temperature.)
Two concentric spheres of diameter D = 0.9 m and D2 = 1.2 m are separated by an air space and have surface temperatures of T = 390 Kand T2 = 300 K. (a) If the surfaces are black, what is the net rate of radiation exchange between the spheres, in W? 912 = i w (b) What is the net rate of radiation exchange between the surfaces if they are diffuse and gray with ej = 0.5 and ez = 0.05, in W? 912 = W (c) What is the net rate of radiation exchange if D2 is increased to 20 m, with e, = 0.05, e = 0.5, and D = 0.9 m, in W? 912 = (d) What is the net rate of radiation exchange if the larger sphere behaves as a black body (82 = 1.0) and with e1 = 0.5, D2 = 20 m, and D, = 0.9 m, in W? 412 =
A typical car's exterior consists of a thin layer of silica (SiO2) over an opaque painted metal panel. Silica is transparent in the visible wavelengths but offers high reflectance in the near- to mid- infrared wavelengths. The plot on the next page depicts the diffuse spectral reflectivity (pa) of the car's surface: Spectral reflectivity, P₂ 0.8 0.6 0.4 ལ 0.2 0 0.1 1 1 10 Wavelength, λ(μm) 100 If the car's exterior temperature is T₁ = 77°C, determine both the total absorptivity (a) and the total emissivity (a) of the silica-covered panel. Assume that the Sun's temperature is Tsun = 5800 K.
Based upon the reradiating properties of absorptivity, reflectivity and transmissivity, how would you distinguish between the following: Black body, white body, transparent body and opaque body.
Two concentric spheres of diameter D = 0.8 m and D2 = 1.2 m are separated by an air space and have surface temperatures of T = 400 K and T2 = 300 K. (a) If the surfaces are black, what is the net rate of radiation exchange between the spheres, in W? 912 = (b) What is the net rate of radiation exchange between the surfaces if they are diffuse and gray with e = 0.5 and e2 = 0.05, in W? 912 = W (c) What is the net rate of radiation exchange if D2 is increased to 20 m, with ɛz = 0.05, ɛ1 = 0.5, and D = 0.8 m, in W? 912 = w (d) What is the net rate of radiation exchange if the larger sphere behaves as a black body (82 = 1.0) and with & = 0.5, D2 = 20 m, and D = 0.8 m, in W? 912 = W
5. (25%) A frustum of a cone has its base heated as shown in Figure 2. The top surface is held at 1200K while the side is perfectly insulated. Surfaces 1, 2, and 3 are assumed gray and diffuse. What are the temperatures of surface 1 and 2? If the emissivity of surface 2 changes from 0,8 to 0.6, will the temperature of surface 2 change to different value? The radius of upper circle is 1 m and the radius of lower circle is 3 m. The height of frustum is 4 m. Surface 3 T= 1200K 8 = 0.8 Surface 1 Surface 2 q= 100W/m? 8 = 0.6 Perfectly insulated ɛ = 0.8
Two concentric spheres of diameter D = 0.7 m and D2 = 1.2 m are separated by an air space and have surface temperatures of T = 400 K and T, = 300 K. (a) If the surfaces are black, what is the net rate of radiation exchange between the spheres, in W? 912 = (b) What is the net rate of radiation exchange between the surfaces if they are diffuse and gray with & = 0.5 and &2 = 0.05, in W? 912 = W (c) What is the net rate of radiation exchange if D2 is increased to 20 m, with &2 = 0.05, €1 = 0.5, and D1 = 0.7 m, in W? 912 = W (d) What is the net rate of radiation exchange if the larger sphere behaves as a black body (82 = 1.0) and with &1 = 0.5, D2 = 20 m, and D = 0.7 m, in W? 912 = W