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Radiant Heat Exchange Parallel Disks Equation and Calculator

Heat Transfer Engineering
Thermodynamics
Engineering Physics

Radiant heat exchange for two isothermal (constant temperature) parallel flat black disks equation and calculator.

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The heat flow (q) from the plate is calculated as:

q = 56.69 x 10^-9 x VF_(1-2) x A₁² x (T₁⁴ - T₂⁴ )

Where 56.69 x 10^-9 is the average Stefan-Bolzmann constant, A₁is the area of the disk, T₁ is the plate 1 temperature and T₂ is the disk 2 temperature. The view factor VF_(1-2) (also known as radiation shape factor, angle factor, and configuration factor) is defined as:

Length of plate 1 divided by the distance between the plates (L 1 / D) must be greater than 0.2 for this calculation.

Where:

r₁ = rad₁ / D
r₂ = rad₂ / D
X = 1 + ( (1 + r₂² ) / r₁²)
A₁ = Area (W)
D = Spacing (m)
rad_1,2 = Radius (m)
T₁ = Plate 1 Temperature (K)
T₂ = Plate 2 Temperature (K)
VF_1-2 = View Factor
q = Radiated Heat Flow (W)

References

Rosenow, W. M., J. P. Hartnett, Y. I. Young, Handbook of Heat Transfer , 3rd Ed., McGraw-Hill Handbooks, New York, 1998. p. 7.3 - 7.19, 7.82.