### 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 A_{1}^{2} x (T_{1}^{4} - T_{2}^{4} )

Where 56.69 x 10^{-9} is the average Stefan-Bolzmann constant, A_{1}is the area of the disk, T_{1} is the plate 1 temperature and *T _{2} *is the disk 2 temperature. The view factor

*VF*(also known as radiation shape factor, angle factor, and configuration factor) is defined as:

_{(1-2)}Length of plate 1 divided by the distance between the plates (L 1 / D) must be greater than 0.2 for this calculation.

Where:

r_{1} = rad_{1} / D

r_{2} = rad_{2} / D

X = 1 + ( (1 + r_{2}^{2} ) / r_{1}^{2})

A_{1} = Area (W)

D = Spacing (m)

rad_{1,2} = Radius (m)

T_{1} = Plate 1 Temperature (K)

T_{2} = 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.

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