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Development of two new semi-empirical formulas for estimation of solar absorptance in circular cavity receivers
摘要： In this paper two new semi-empirical formulas for calculating the equivalent absorptance of solar irradiation at the inner surface of cylindrical cavities is proposed. The multiple re?ections that occur at the interior of the cavity were ?rst analyzed considering a two-dimensional geometrical approach and thus the ?rst analytical relationship for the equivalent solar absorptance was revealed. In addition, a three-dimensional ray tracing analysis was conducted through Solidworks Flow Simulation. Several di?erent cavity aperture’s widths as well as solar absorptance coe?cients (α = 0.5–0.9 per 0.1) were examined in both analyses and it was found that the two dimensional analytical approach exceeds the simulation by 1.50–6.83% on average going from the highest to the lowest solar absorptance value. Finally, two new correlations were developed for correcting the analytical approach according to the 3D ray tracing with the optimum between them to provide a mean error at the equivalent solar absorptance calculation of about 0.78%, 0.55%, 0.40%, 0.21% and 0.18% for the ?ve di?erent absorptance coe?cients were examined.
关键词： Solidworks Flow Simulation,Solar absorptance,Cavity receiver,Optical analysis,New correlation
更新于2025-09-19 17:15:36
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Solar Engineering of Thermal Processes, Photovoltaics and Wind || Radiation Characteristics of Opaque Materials
摘要： This chapter begins with a detailed discussion of radiation characteristics of surfaces. For many solar energy calculations only two quantities are required, the solar absorptance and the long-wave or infrared emittance, usually referred to as just absorptance and emittance. Although values of these two quantities are often quoted, other radiation properties may be the only available information on a particular material. Since relationships exist between the various characteristics, it may be possible to calculate a desired quantity from available data. Consequently, it is necessary to understand exactly what is meant by the radiation terms found in the literature, to be familiar with the type of information available, and to know how to manipulate these data to get the desired information. The most common type of data manipulation is illustrated in the examples, and readers may wish to go directly to Section 4.5.
关键词： selective surfaces,solar energy,infrared emittance,solar absorptance,radiation characteristics
更新于2025-09-16 10:30:52