Topic
Radiative transfer
About: Radiative transfer is a research topic. Over the lifetime, 43287 publications have been published within this topic receiving 1176539 citations.
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TL;DR: In this article, a metamaterial thermal emitter for highly efficient radiative cooling is demonstrated, which selectively radiates within the atmospheric transparency window and minimizes absorption of atmospheric radiation outside the transparency window.
Abstract: A metamaterial thermal emitter for highly efficient radiative cooling is demonstrated. The emitter selectively radiates within the atmospheric transparency window and minimizes absorption of atmospheric radiation outside the transparency window. Exploiting its intriguing radiative properties, the emitter has the ability to deliver a remarkably high cooling power of more than 100 W m−2 and to cool down 12 °C below the ambient temperature.
431 citations
TL;DR: The basic principles of radiative cooling and its performance characteristics for nonradiative contributions, solar radiation, and atmospheric conditions are discussed and the recent advancements over the traditional approaches and their material and structural characteristics are outlined.
Abstract: The recent progress on radiative cooling reveals its potential for applications in highly efficient passive cooling. This approach utilizes the maximized emission of infrared thermal radiation through the atmospheric window for releasing heat and minimized absorption of incoming atmospheric radiation. These simultaneous processes can lead to a device temperature substantially below the ambient temperature. Although the application of radiative cooling for nighttime cooling was demonstrated a few decades ago, significant cooling under direct sunlight has been achieved only recently, indicating its potential as a practical passive cooler during the day. In this article, the basic principles of radiative cooling and its performance characteristics for nonradiative contributions, solar radiation, and atmospheric conditions are discussed. The recent advancements over the traditional approaches and their material and structural characteristics are outlined. The key characteristics of the thermal radiators and solar reflectors of the current state-of-the-art radiative coolers are evaluated and their benchmarks are remarked for the peak cooling ability. The scopes for further improvements on radiative cooling efficiency for optimized device characteristics are also theoretically estimated.
430 citations
TL;DR: In this article, the authors investigated the open-circuit voltage of methylammonium lead iodide perovskite solar cells and showed that without a hole-transport layer, non-radiative recombination is strongly enhanced, which reduces the open circuit voltage.
Abstract: The remarkably high open-circuit voltage of methylammonium lead iodide perovskite solar cells is investigated. Both the theoretical maximum and the real open-circuit voltage are predicted from electroluminescence and photovoltaic external quantum efficiency spectra. Radiative and non-radiative recombination are quantified, where a source of non-radiative recombination is found in the mesoscopic structure, independent of the Al2O3 or TiO2 scaffold. Without a hole-transport layer, non-radiative recombination is strongly enhanced, which reduces the open-circuit voltage. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
428 citations
TL;DR: In this paper, the spectral inversion technique has been used to infer the plasma parameters important for the general properties of the prominence plasma in both its cool core and the hotter prominence-corona transition region.
Abstract: This review paper outlines background information and covers recent advances made via the analysis of spectra and images of prominence plasma and the increased sophistication of non-LTE (i.e. when there is a departure from Local Thermodynamic Equilibrium) radiative transfer models. We first describe the spectral inversion techniques that have been used to infer the plasma parameters important for the general properties of the prominence plasma in both its cool core and the hotter prominence-corona transition region. We also review studies devoted to the observation of bulk motions of the prominence plasma and to the determination of prominence mass. However, a simple inversion of spectroscopic data usually fails when the lines become optically thick at certain wavelengths. Therefore, complex non-LTE models become necessary. We thus present the basics of non-LTE radiative transfer theory and the associated multi-level radiative transfer problems. The main results of one- and two-dimensional models of the prominences and their fine-structures are presented. We then discuss the energy balance in various prominence models. Finally, we outline the outstanding observational and theoretical questions, and the directions for future progress in our understanding of solar prominences.
428 citations
20 Oct 1999
TL;DR: The MODTRAN ground surface has been upgraded to include the effects of Bidirectional Reflectance Distribution Functions (BRDFs) and Adjacency as discussed by the authors, and the BRDFs are coupled into line-of-sight surface radiance calculations.
Abstract: MODTRAN4, the latest publicly released version of MODTRAN, provides many new and important options for modeling atmospheric radiation transport. A correlated-k algorithm improves multiple scattering, eliminates Curtis-Godson averaging, and introduces Beer's Law dependencies into the band model. An optimized 15 cm-1 band model provides over a 10-fold increase in speed over the standard MODTRAN 1 cm-1 band model with comparable accuracy when higher spectral resolution results are unnecessary. The MODTRAN ground surface has been upgraded to include the effects of Bidirectional Reflectance Distribution Functions (BRDFs) and Adjacency. The BRDFs are entered using standard parameterizations and are coupled into line-of-sight surface radiance calculations.
427 citations