Accession Number : ADA116737
Title : Thermal Radiation from Hot Surfaces Measured by Optical and Calorimetric Methods.
Descriptive Note : Master's thesis,
Corporate Author : AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH
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