There are some methods to calculate the integrated cavity emissivity. Because of the existence of the penumbral region, the results obtained from these methods deviate from the exact values. In this paper, we pay special attention to solve the penumbral region problem and put a new method to calculate precisely the integrated cavity emissivity of the diffuse conical and cylindrical cavity. T h s method can also be used to calculate for isothermal or non-isothermal, symmetric-axis, diffuse cavities. Some numerical and typical results are also given here.

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In the present investigation, the integral equation for the temperature distribution inside the cavity at the gold freezing point, and the relation between the emissivity and the local temperature have been derived according to the basic ideas of Geist. In addition, we have calculated the changes of the temperature and emissivity of the bottom of a baffled cylindrical cavity due to the changes in the temperature of the baffle. Some typical results are given here.