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Visible and infrared absorption spectra of covering materials for solar collectors
2008
Pelece, I., Latvia Univ. of Agriculture, Jelgava (Latvia)
Use of solar energy increases every year. In Latvia, solar energy is used mainly by solar collectors. The main part of the solar collector is the absorber, but not less important is the covering material which protects the absorber from the cooling impact of the wind. This cover must be transparent for solar radiation, but opaque for thermal radiation of the absorber, which is at greater wavelengths. Therefore it is important to measure absorption spectra of possible covering materials at visible and infrared wavelength ranges. Absorption spectra have been measured for several materials: glass, polythene, Plexiglas, and cells Plexiglas. Absorption spectra for all these materials are measured in three ranges: ultraviolet – visible (UV – VIS): 250 – 1000 nm; near infrared (NIR): 700 – 110 nm; infrared (IR): 1200 – 8000 nm. UV-VIS spectra with the ‘Ocean Optics’ device HR-4000 have been measured, but NIR and IR – with ‘Bruker’ Furje spectrometer EQUINOX 55. Evaluation of absorption spectra showed that the most suitable material (from the considered) for covering of solar collectors is Plexiglas.
اظهر المزيد [+] اقل [-]Changes in cold pressed rapeseed oil quality in different packaging materials during storage
2007
Bluka, A., Latvia Univ. of Agriculture, Jelgava (Latvia) | Cakste, I., Latvia Univ. of Agriculture, Jelgava (Latvia)
The dynamic of rapeseed oil oxidizing processes under the influence of light in brown glass, colourless glass, and colourless PET bottles during storage at 18+-2 deg C were investigated. The changes in A and E vitamins content in rapeseed oil packed in colourless PET packaging materials were determined after 4 months storage at 18+-2 deg C at daylight. The connection between different packaging materials' transparency and oxidizing of oil were observed.
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