Apparent emittance of non-isothermal particulate deposits

This paper presents an analysis of a commonly used total emittance measurement technique for particulate deposits. The analysis indicates that apparent emittance of a non-isothermal particulate deposit could be significantly different from the isothermal emittance if there is a substantial temperature gradient across it and the deposit is composed of transparent material or coarse particles. Results indicate that care must be exercised in experimental set-up design and data reduction in order to have accurate inference of emittance or absorbance from such measurements.