Showing papers by "Claes-Göran Granqvist published in 1982"
TL;DR: The influence of altered contents of water vapor was found to affect strongly the radiative cooling, whereas changes in ozone and aerosol abundance were less important.
Abstract: Calculations of spectral radiance are reported from several model atmospheres appropriate to different climatic conditions by use of the LOWTRAN 5 computer code. From these data we evaluate the radiative cooling power and the temperature drop below ambient temperature for horizontal surfaces that radiate toward the sky. The surfaces are ideal blackbodies or have ideal infrared-selective properties with zero reflectance in the 8-13-microm range and unity reflectance elsewhere. For freely radiating surfaces, the cooling power at ambient temperature lies between 58 Wm(-2) and 113 Wm(-2) for the different surfaces and model atmospheres. The maximum temperature difference for a device with a nonradiative heat transfer coefficient of 1 Wm(-2) K(-1) is between 11 and 21 degrees C for a blackbody and between 18 and 33 degrees C for an infrared-selective surface. For radiators arranged so that they intercept only the atmospheric zenith radiance, the cooling powers and temperature differences are higher than for freely radiating surfaces, the increase being largest for humid atmospheres. The influence of altered contents of water vapor was found to affect strongly the radiative cooling, whereas changes in ozone and aerosol abundance were less important. The significance of these results to different cooling applications is briefly discussed.
116 citations
TL;DR: In this paper, a transparent and heat reflecting indium tin oxide films were prepared by electron beam evaporation of In2O3+9 mol.% SnO2 onto glass in an oxygen atmosphere of ∼5×10−4 Torr.
Abstract: Transparent and heat reflecting indium tin oxide films were prepared by electron beam evaporation of In2O3+9 mol.% SnO2 onto glass in an oxygen atmosphere of ∼5×10−4 Torr. Visible light absorption less than 2%, thermal infrared reflectance exceeding 90%, and a dc resistivity of ∼3×10−4 Ω cm were obtained for 0.3‐μm‐thick films deposited on a substrate at 300 °C. Similar properties could be achieved with substrate temperatures as low as 150 °C. By antireflection coating the films with an MgF2 layer, the visible transmittance exceeded the transmittance of the uncoated glass while the infrared reflectance was practically unchanged.
96 citations
TL;DR: In this paper, the authors outline a theretical analysis of the required radiative properties and report some small-scale experiments using evaporated SiO and “Si 3 N 4 ” films.
77 citations
TL;DR: Transparent and heat-reflecting indium tin oxide films were prepared by electron beam evaporation of In 2 O 3 9mol%SnO 2 in an oxygen atmosphere of about 5×10 −4 Torr as discussed by the authors.
74 citations
TL;DR: In this article, spectral measurements for NH3 gas layers are reported, and the potential use of this substance in radiative cooling devices is evaluated; the basic cooling parameters and the radiated power versus temperature drop are computed: the cooling power at near ambient temperature can be exceptionally large.
Abstract: Spectrophotometric measurements are reported for NH3 gas layers, and the potential use of this substance in radiative cooling devices is evaluated. The basic cooling parameters and the radiated power versus temperature drop are computed: the cooling power at near‐ambient temperature can be exceptionally large. The radiative properties are discussed from the configuration of the NH3 molecule. Typically a 2‐cm‐thick NH3 gas slab can provide 26 Wm−2 useful cooling power at 15 °C below ambient temperature in a device with a moderate nonradiative loss (heat transfer coefficient of 1 Wm−2 K−1).
54 citations
TL;DR: In this article, the solar absorptance and thermal emittance for Al2O3 films on Al were derived by using the previous determination of the dielectric function for evaporated Al 2O3.
17 citations
12 Apr 1982
TL;DR: In this paper, transparent and heat-reflecting Indium-Tin-Oxide (ITO) films were prepared by well controlled reactive electron-beam evaporation of In203+ 9 mol.
Abstract: We report on transparent and heat-reflecting Indium-Tin-Oxide (ITO) films prepared by well controlled reactive electron-beam evaporation of In203+ 9 mol. % SnO2 onto glass in - 5x 10-4 Torr of 02. Typical results for 0.3 pm thick films deposited on substrates at 300°C were: visible light absorptance 90 %, and dc resistivity 3x 10-4 Qcm. Similar properties were found for substrate temperatures down to 150°C, whereas a rapid deterioration took place at still lower temperatures. After antireflection coating with -0.1 pm of evaporated MgF2, the visible transmittance became - 1% larger than that of the uncoated glass, while the infrared reflectance increased by a few percent only. The ITO+ MgF2 coatings show much weaker iridescence than the bare ITO films.
12 citations