FT-IR measurements of emissivity and temperature during high flux solar processing
- Advanced Fuel Research, Inc., East Hartford, CT (United States); and others
The experimental capability to generate and utilize concentrated solar flux has been demonstrated at a number of facilities in the US. To advance this research area, the National Renewable Energy Laboratory (NREL) has designed and constructed a versatile High Flux Solar Furnace (HFSF). Research is ongoing in areas of material processing, high temperature and UV enhanced detoxification, chemical synthesis, high flux optics, solar pumped lasers, and high heating rate processes. Surface modifications via concentrated solar flux, however, are currently performed without the means to accurately monitor the temperature of the surface of interest. Thermoelectric and pyrometric devices are not accurate due to limitations in surface contact and knowledge of surface emissivity, respectively, as well as interference contributed by the solar flux. In this article, the authors present a noncontact optical technique that simultaneously measures the directional spectral emissivity, and temperature of the surface during solar processing. A Fourier Transform Infrared (FT-IR) spectrometer is coupled to a processing chamber at NREL`s HFSF with a fiber-optic radiation transfer assembly. The system measures directional emission and hemispherical-directional reflectance in a spectral region that lacks contribution from solar flux. From these radiative property measurements during solar processing, the spectral emittance and temperature at the measurement point can be obtained. The methodology, validation measurements, and in-situ measurements during solar processing of materials are presented. Knowledge of surface temperature during solar processing is an important parameter for process control. Based on validation measurements for spectral emittance, the temperature error associated with the novel instrument is less than {+-} 5% for surfaces of mid-range emittance.
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- FG05-90ER80879
- OSTI ID:
- 230813
- Journal Information:
- Journal of Solar Energy Engineering, Journal Name: Journal of Solar Energy Engineering Journal Issue: 1 Vol. 118; ISSN JSEEDO; ISSN 0199-6231
- Country of Publication:
- United States
- Language:
- English
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