Premium
Measurement of radiation emitted from thin vaporizing liquid films for the calculation of surface temperature
Author(s) -
Hahn Kai,
Mewes Dieter
Publication year - 1992
Publication title -
chemical engineering and technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.403
H-Index - 81
eISSN - 1521-4125
pISSN - 0930-7516
DOI - 10.1002/ceat.270150404
Subject(s) - pyrometer , radiation , evaporation , optics , materials science , wavelength , thin film , thermal radiation , stray light , chemistry , analytical chemistry (journal) , temperature measurement , thermodynamics , physics , chromatography , nanotechnology
Evaporation of liquid films, not subjected to motion, and with a starting thickness of 1 mm, was tested. Solvents dichloromethane and ethanol were used as liquids. Surface temperature during evaporation was measured in a non‐intrusive way using pyrometry. The employed pyrometer was calibrated against a black body radiant. Measurement accuracy in the region of the ambient temperature is 0.2 K. Since any principal stray radiation is always measured along with the thermal radiation emitting from the liquid film, the measurement results are at first distorted. A correction calculation is described. With this, the various proportions of stray radiation can be subsequently calculated. In order to do this, the dimensions of the test equipment and the spectral data of the evaporating solvents must be taken into account. The quantity of stray radiation depends mainly on the properties of the surface onto which the liquid film is applied, as well as on the spectral transmissivity of the liquid. This was measured for every tested liquid according to wavelength and layer thickness. Where the spectral transmissivity of a liquid is low, a correction calculation of the measured surface temperature is not necessary, while a high level of accuracy is still retained.