Solar energy utilization by a greenhouse: General relations
Solar energy utilization by a greenhouse: General relations
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温室对太阳能的利用：一般关系
DOI：
10.1016/j.renene.2010.06.020
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发表时间：
2011
期刊：
影响因子：
8.7
通讯作者：
I. Al
中科院分区：
文献类型：
--
作者：
A. Abdel;I. Al
入射到温室上的大部分太阳辐射被温室组件吸收（即，覆盖物、潮湿空气、植物和土壤），剩余部分损失到温室外部。了解温室的吸收和损失能量对于温室的热分析是至关重要的。现有的温室热模型使用温室组分的辐射特性来直接确定吸收的能量项。然而，这些模型忽略了损失的能量项，忽略了温室组件之间的太阳辐射的多次反射的影响。本研究描述的一般关系，估计温室组件吸收的太阳能和损失到温室外的量。这些关系考虑到了这些组成部分之间的相互关系以及太阳辐射的多次反射。因此，温室系统被视为具有吸收器板的太阳能收集器（即，温室土壤）和由三个半透明平行层（即，温室覆盖物、潮湿的空气和植物）。采用叠加理论和射线追踪技术进行了分析。所提出的关系被应用到一个实验性的塑料覆盖的温室，占地面积为34平方米。位于沙特阿拉伯利雅得的温室种植叶面积指数（LAI）为3.0的番茄，并通过湿垫和风扇系统冷却。与文献报道的其他关系式相比，所提出的关系式的结果更准确，更符合实际。温室内水汽对太阳辐射的吸收可以忽略不计。当叶面积指数小于1.5时，该关系式可精确估算温室的吸收和损失能量项，每项的最大可能误差为+1.8%。当温室内叶面积指数增加到5时，误差显著减小到± 0.7%。
Most of solar radiation incident on a greenhouse is absorbed by greenhouse components (i.e., the cover, humid air, plants and soil) and the remaining portion is lost to outside the greenhouse. It is essential to know the absorbed and lost energy terms for any thermal analysis of greenhouses. Existing greenhouse thermal models use the radiative properties of the greenhouse components to directly determine the absorbed energy terms. However, these models neglect the lost energy term and neglect the effects of the multiple reflections of solar radiation between the greenhouse components. The present study describes the general relations for estimating the amounts of solar energy absorbed by the greenhouse components and lost to outside the greenhouse. The relations take into consideration the interrelations as well as the multiple reflections of solar radiation between these components. Thus, the greenhouse system was treated as a solar collector having an absorber plate (i.e., the greenhouse soil) and a cover system consisting of three semi-transparent parallel layers (i.e., the greenhouse cover, the humid air, and the plants). Superposition theory and ray tracing technique were used for the analysis. The presented relations were applied to an experimental plastic-covered greenhouse with a floor area of 34 m2. The greenhouse, located in Riyadh, Saudi Arabia, was planted with tomatoes with a leaf area index (LAI) of 3.0 and was cooled by a wet pad and fan system. Results of the presented relations were accurate and more realistic comparing to results of other relations reported in the literatures. Absorption of solar radiation by water vapor in the greenhouse was negligible. The presented relations can estimate the absorbed and lost energy terms for a greenhouse precisely with a max possible error of +1.8% on each term if the LAI was less than 1.5. The error is significantly decreased to less than +0.7% if the LAI in the greenhouse is increased to 5.