Gebhart factor
The Gebhart factors are used in radiative heat transfer, it is a means to describe the ratio of radiation absorbed by any other surface versus the total emitted radiation from given surface. As such, it becomes the radiation exchange factor between a number of surfaces. The Gebhart factors calculation method is supported in several radiation heat transfer tools, such as TMG and TRNSYS. The method was introduced by Benjamin Gebhart in 1957. Although a requirement is the calculation of the view factors beforehand, it requires less computational power, compared to using ray tracing with the Monte Carlo Method (MCM). Alternative methods are to look at the radiosity, which Hottel and others build upon. Equations The Gebhart factor can be given as: . The Gebhart factor approach assumes that the surfaces are gray and emits and are illuminated diffusely and uniformly. This can be rewritten as: where is the Gebhart factor is the heat transfer from surface i to j is the emissivity of the surface is the surface area is the temperature The denominator can also be recognized from the Stefan–Boltzmann law. The factor can then be used to calculate the net energy transferred from one surface to all other,