Pyrometric Temperature Measurements in Solar Furnaces

Abstract

Surface temperatures are key parameters in many applications of concentrated solar radiation. Pyrometric temperature determination is, however, hampered by reflected solar radiation. Two approaches to solve this problem were experimentally tested on a solar reactor at the Paul Scherrer Institute (PSI): the flash assisted multi-wavelength pyrometry (FAMP) developed at PSI and a solar-blind pyrometer developed by the IMPAC Electronic GmbH in Frankfurt, Germany, in collaboration with PSI. Performance, advantages, and disadvantages of the two pyrometers are reported and discussed.

Kinetics on a Second Scale at Temperatures up to 2300 K—The Reduction of Manganese Oxide in a Solar Furnace

“…The modifications necessary to determine the mean residence time are the tracer inlet (5) to release oxygen at the position of the sample (2) and a three‐way valve (6). Surface temperatures of the sample were measured by means of flash‐assisted multi‐wavelength pyrometry (FAMP) 5 and a so‐called solar blind pyrometer 6 . FAMP provides the surface temperature and also the actual spectral reflectance of the sample and the spectral irradiance of the incident radiation in the range of 550–1000 nm under the only condition that the sample is opaque and its surface is close to lambertian, i.e., that it reflects light evenly in all directions.…”

“…A detailed description of the reactor, its periphery, and the characterization is given elsewhere. 3 The modifications necessary to determine the mean residence time are the tracer inlet (5) to release oxygen at the position of the sample (2) and a three-way valve (6). and a so-called solar blind pyrometer.…”

Review of Heat Transfer Research for Solar Thermochemical Applications

“…Pyrometry temperature measurements are based on the thermal emission from a surface and are commonly employed in the fields of concentrating solar, gas turbines, metallurgy, and surface processing [120][121][122][123][124][125][126][127][128][129]. It offers the advantages that the sensor is outside the harsh measurement environment and has rapid time response.…”

“…The most common approach to radiation-based temperature measurement in solar reactors is solar-blind pyrometry, which takes advantage of the natural attenuation of certain bandwidths in the solar radiation spectrum by water vapor and carbon dioxide in the atmosphere [121,126,127]. Bandpass filters are placed in the line of sight between the radiation sensor and the surface of interest that allow only the atmosphere attenuated wavelengths of radiation to enter the sensor so that the radiation arriving at the sensor is solely the result of thermal emission from the surface [123][124][125].…”

“…The reflected radiation includes the concentrated radiation delivered to the solar reactor, either from a solar furnace or a solar simulator, and also emitted radiation from other high-temperature surfaces in view of the surface of interest. In solar furnaces, three methods have been developed for decoupling the emitted and reflected parts of the radiosity: flash assisted multiwavelength pyrometry (FAMP) [121,[130][131][132], pyroreflectometry [133][134][135], and solar-blind pyrometry [121,[123][124][125][126][127]136]. An advantage of FAMP and pyroreflectometry is that, in addition to decoupling thermal emission from the surface radiosity, the emissivity of the surface e k is measured in situ.…”