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Photothermal/day lighting performance analysis of a multifunctional solid compound parabolic concentrator for an active solar greenhouse roof
摘要： Currently, the excess light above a light saturation point cannot be harnessed for plant growth in conventional greenhouse covers. In this study, we developed a solid compound parabolic concentrator (CPC) cover for use in greenhouses to convert excess light into heat. Optical simulation software was used to track the sunlight at different incident angles over time. We also conducted experiments to determine the transmittance and heating power of the solid CPC coating under real weather conditions. The maximum instantaneous thermal efficiency and thermal energy of a single solid CPC cover plate were 32.2% and 353 W/m2, respectively. The simulation results were in good agreement with the experimental output power and the trend of the actual transmittance of the covering material. The transmittance of the covering material was low when the midday sun was intense, and the transmittance was relatively high in the morning and afternoon. The variation of red and blue light in the greenhouse with the spectrum was analyzed at the same time. Studies have shown that this new greenhouse covering material can better adjust the brightness, make the illumination in the greenhouse more uniform, and thus improve the thermal environment in the greenhouse. The heat pipes converted excess light into heat, thereby achieving comprehensive utilization of solar light and heat.
关键词： Heat energy utilization,Solid CPC,Solar greenhouse roof,Light transmittance,Solar PT/D system
更新于2025-09-23 15:22:29
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Phase transitions and critical phenomena of tiny grains carbon films synthesized in microwave-based vapor deposition system
摘要： Different peak trends of tiny grains carbon film have been observed under the investigations of the Raman spectroscopy and energy loss spectroscopy. Carbon films known in nanocrystalline and ultrananocrystalline diamond films are synthesized by employing microwave‐based vapor deposition system. Carbon atoms exhibit several state behaviors depending on the incurred positions of their electrons. Different morphology of tiny grains under different chamber pressure is related to different rate of arriving typical energies at/near substrate surface. Those tiny grains of carbon film, which evolved in graphitic state atoms are converted to structure of smooth elements where elongation of atoms of one‐dimensional arrays is as per exerting surface format forces along opposite poles from their centers. Such tiny grains in the film are the cause of v1 peak under the investigation of the Raman spectrum because of the enhanced propagation of input laser signals through channelized inter‐state electron gaps of elongated graphitic state atoms. Those tiny grains of carbon film, which evolved in fullerene state are the cause of v2 peak. The tiny grains related to v1 peak possess a low intensity as compared with the ones which comprised atoms having state behaviors known in their exceptional hardness. Tiny grains representing v1 peak in the Raman spectrum are also the cause of field emission characteristic of a carbon film. Different peak recordings were made for the Raman at defined positions indicating a different state of carbon atoms for a different phase of deposited tiny grains, which is in line to their energy loss spectroscopy.
关键词： field emission,tiny grains carbon films,Raman spectra,phase transition,heat energy,energy loss spectroscopy
更新于2025-09-23 15:21:01