SPECTRAL SELECTIVE RADIATING MATERIALS FOR DIRECT RADIATIVE HEATING

摘要

It is known that the atmosphere shows high transmittance between 8 and 13 micrometers in wavelength and this wavelength region is called ‘atmospheric window’. In other words, the atmosphere shows relatively high absorption except the atmospheric window. Conventional infrared radiants for heating emit IR radiation spectrally broadly and make energy loss because of the absorption by the atmosphere. This loss is not negligible in a large space. Meanwhile spectral selective radiating material (SSRM) for radiative cooling to low temperatures, such as an SiO film on Al substrate, emits the IR radiation only between 8and 13 micrometers. Using the SSRM as a spectral selective radiant (SSR) for heating, we can heat the objectives directly decreasing the energy loss due to the atmospheric absorption. Our SiO/Al samples were deposited by vacuum evaporation on glass substrates. The thickness of the SiO film was about 1 μm. Spectral emittance in IR region was measured by an FT-IR with two furnaces for the blackbody and the sample. To confirm the direct heating properties, we measured spectral transmittance of the atmosphere and calculated radiance reaching arbitrary distance form the radiant. As a result, the IR radiation emitted from the SSR at a distance of 10 meter was about 10 % greater than that from the blackbody, depending on the atmospheric condition.