What is the reciprocity relation for view factors between two surfaces, i and j?
Explanation
The reciprocity relation is a crucial property of view factors that relates the view factor from surface i to j with the view factor from j to i, incorporating their respective areas. It allows for the calculation of one view factor if the other is known, reducing the number of direct calculations needed for an enclosure.
Other questions
What is the definition of the view factor Fij?
What does the summation rule for an N-surface enclosure state for a specific surface i?
Two diffuse surfaces, A1 and A2, have areas of 2 square meters and 4 square meters, respectively. If the view factor from surface A1 to A2 (F12) is 0.4, what is the view factor from A2 to A1 (F21)?
For which of the following surface geometries is the view factor from the surface to itself (Fii) guaranteed to be zero?
In the context of radiation exchange, what does the term radiosity (Ji) represent?
For a diffuse, gray surface 'i' in an enclosure, the net radiative heat transfer rate (qi) can be represented as a potential difference divided by a resistance. What is the expression for this surface radiative resistance?
What is the expression for the space or geometrical resistance between two diffuse, gray surfaces, 'i' and 'j', in a radiation network?
A diffuse, gray sphere of diameter D is placed inside a cubical box of length L = D. What is the view factor from the cubical box (surface 2) to the sphere (surface 1)?
Two large, diffuse, gray, parallel plates are maintained at 600 K and 325 K. Their emissivities are 0.7. What is the net radiation exchange per unit area between the plates? Use the Stefan-Boltzmann constant of 5.67 x 10^-8 W/m^2K^4.
What is the primary function of a radiation shield when placed between two surfaces exchanging heat?
A thin radiation shield with an emissivity of 0.1 on both sides is placed between two large, parallel blackbody plates (emissivity = 1.0). By what factor is the net radiation transfer rate reduced due to the shield?
A thin radiation shield with an emissivity of 0.02 on both sides is inserted midway between two large, parallel, diffuse, gray plates. The primary plates have emissivities of 0.9. By what approximate factor is the heat transfer reduced due to the shield?
Which condition defines a surface as being a 'reradiating surface' in an enclosure analysis?
The equilibrium temperature of a reradiating surface is determined by its radiative interaction with other surfaces in the enclosure. This equilibrium temperature is independent of which property of the reradiating surface itself?
In a multimode heat transfer analysis for a surface in an enclosure, the surface energy balance is given by qi,ext + qi,rad + qi,conv + qi,cond = 0. How is the net radiation transfer from the surface, qi,rad, determined?
What physical law describes the exponential decay of monochromatic radiation intensity as it passes through an absorbing gas or liquid layer?
In a three-surface enclosure consisting of two large parallel plates (1 and 2) and a reradiating surface (R) connecting them, what is the correct expression for the net radiation exchange, q1?
A long cylindrical heater of radius 10 mm and emissivity 0.8 is at 1000 K. It is centered inside a long tube of radius 20 mm and emissivity 0.6, which is at 500 K. The space is evacuated. What is the net rate of radiation exchange per unit length of the tubes? Use the Stefan-Boltzmann constant of 5.67 x 10^-8 W/m^2K^4.
Radiation is leaving a diffuse, gray surface 'i' which is part of an enclosure. The rate of this radiation being intercepted by another surface 'j' is qi->j. How does qi->j relate to the radiosities of the surfaces?
For an opaque, diffuse, gray surface, the radiosity Ji is given by Ji = epsilon_i * Ebi + (1 - epsilon_i) * Gi. What does the term (1 - epsilon_i) represent?
What is the simplified expression for the net radiation exchange from a blackbody surface 'i' (qi) in an enclosure of other blackbody surfaces?