Accession Number : ADA116737

Title :   Thermal Radiation from Hot Surfaces Measured by Optical and Calorimetric Methods.

Descriptive Note : Master's thesis,


Personal Author(s) : O'Connor,Gerald Thomas

PDF Url : ADA116737

Report Date : Jan 1982

Pagination or Media Count : 106

Abstract : The radiative heat loss from a surface is determined by its total hemispherical emittance, which consequently plays an important role in aerospace and solar applications. This study compares emittances measured calorimetrically with values derived from near normal incidence spectral reflectance measurements. This optical derivation is based on a number of assumptions which limit the accuracy if not sufficiency fulfilled. These assumptions include sample specularity, a straybody character beyond the range of measurement, only small variations of emittance with temperature, and a perfectly smooth sample surface. The comparison of calorimetrically and optically derived emittance performed in this study not only quantifies the errors introduced by insufficient fulfillment of the assumptions but also identifies which assumption causes the dominant error. The calorimetric emissometer, constructed for this study and based on a heat flow sensor, was calibrated with aluminum and nickel thin films, resulting in good agreement with literature values.

Descriptors :   *Emittance, Surfaces, Heat, Thermal radiation, Absorption, Reflectance, Radiative transfer, Measurement, Optical properties, Calorimetry, Vacuum apparatus, Emissometers, Theses

Subject Categories : Optics

Distribution Statement : APPROVED FOR PUBLIC RELEASE