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Analysis of solar radiation changes in Chinese solar greenhouses with different roof structures based on a solar radiation model

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International Journal of Agricultural and Biological Engineering 2022年第2期15卷 221-229页

作者： Kai Liu Hongjun Xu Hong Li Xiao Wu Siyu Sang Jie Gao Department of horticulture College of HorticultureXinjiang Agricultural UniversityUrumqi 830052China Department of Horticulture Center for Postdoctoral Studies of Xinjiang Agricultural UniversityUrumqi 830052China

Chinese solar greenhouses(CSGs)are important agricultural production facilities.Under non-artificial heating conditions,solar radiation is the only CSGs energy source.It is highly important to optimally obtain solar energy in greenhouse construction and production.In this study,a solar radiation model for solar greenhouses was adopted to explore the quantities of solar radiation in greenhouses considering different front roof forms and angles.Herein,the solar radiation amounts corresponding to five roof forms,namely,double-section arc,parabolic,oval,arc,and linear roofs,are compared and analyzed during the four solar periods(beginning of spring,vernal equinox,beginning of winter,and winter solstice).It was found that the solar radiation of oval roof greenhouses on the ground was the largest and was 4.44%-23.68%higher than that of parabolic roofs.In addition,the cumulative sum of light on the linear roof greenhouse wall is also the largest and was 6.02%to 12.08%higher than the parabolic roof greenhouse in the four solar terms.Moreover,the solar radiation in CSGs was compared with front roof angles of 25°,30°,and 35°.It was observed that the solar radiation amount gradually increases with increasing angles.Notably,the variation at an angle of 35°influences the solar radiation of the paraboloidal CSGs ground and elliptical CSGs north wall to the greatest extent,which increased by 8.23%and 12.74%,respectively.This study confirms the role of front roof form and inclination angle in enhancing the greenhouse solar radiation level.

关键词： Chinese solar greenhouse roof structure roof angle solar radiation model

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Improved Ray-Tracing Arithmetic of solar radiation model Under Larix Dahuric

Improved Ray-Tracing Arithmetic of Solar Radiation Model Und...

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作者： Lei Zhang Haiye Yu Zhiping Zhang Lina Zhou Bin Jiang Key Laboratory of Bionic Engineering Ministry of EducationSchool of Biological and Agricultural EngineeringJilin University

A method calculating ray-tracing of solar radiation distribution model under the Larix dahuric was improved to scientifically evaluate and estimate light environment for planting ginseng under forest scientifically.This method considered neighborhood zone of solar radiation,slope angle(α)and aspect(β),which were absent in existent studies.Besides,discussion about relative location between the ray and the canopy was made in more details than other researches.This improvement depended on aspect(β) related three-dimensional and two-dimensional Cartesian coordinate systems,which were established on slope and horizontal respectively.Furthermore,coordinates conversion was achieved by slope angle(α),aspect(β) and the solar elevation angles(θ).Confirmed extension of neighborhood of light protection was a rectangle with 2H(tree height) on the east and west,0.8H on the south and 0.3H on the north removed from the point where radiation would be calculated.The direct radiation model based on improved arithmetic was also validated under the forests in JingYue Reservoir in Changchun.The regressions analysis between measured and calculated instantaneous values of points and accumulative total value of any point were both made.The regression analysis between measured and calculated instantaneous values of points without sunflecks with 12 cm diameter and discriminated trunk-shading by statistics,coefficients of determination R were not less than 0.664(P model was excellent to estimate direct radiation of most of fixed points in Larix dahuric trees with conical canopies.And it had higher predictions to simulate accumulative solar radiation of any point on soil

关键词： Improved Ray-Tracing Arithmetic solar radiation model Slope Under Larix Dahuric Planting Ginseng

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Numerical Investigation of the Temperature and Flow Fields in a solar Chimney Power Plant

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Fluid Dynamics & Materials Processing 2023年第4期19卷 1055-1066页

作者： Roudouane Laouar Olaf Wünsch Laboratory of Environment Larbi Tebessi UniversityTebessaAlgeria Department of Fluid Dynamics University of KasselKasselGermany

In this work,a parametric two-dimensional computational fluid dynamics(CFD)analysis of a solar chimney power plant(a prototype located in Manzanares,Spain)is presented to illustrate the effects of the solar radiation mode in the collector on the plant performances.The simulations rely on a mathematical model that includes solar radiation within the collector;energy storage;air flow and heat transfer,and a turbine.It is based on the Navier-Stokes equation for turbulent flow formulated according to the standard k-εmodel.Moreover,the Boussinesq approach is used to account for the fluid density variations.Different solar radiation modes in the collector are compared and discussed.The obtained results are also compared with available experimental results.It is shown that the radiation model is essential to avoid overestimation of the energy absorbed by the plant and that results based on a two-dimensional model can resemble closely those produced by three-dimensional models.

关键词： solar radiation model two-dimensional axisymmetric model Boussinesq model greenhouse effect

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Experimental and numerical research on squat silo and large size horizontal warehouse during quasi-steady-state storage

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International Journal of Agricultural and Biological Engineering 2016年第6期9卷 214-222页

作者： Ren Guangyue Liu Yanan Peng Wei Duan Xu Zhang Ledao College of Food and Bioengineering Henan University of Science&TechnologyLuoyang 471023China

Traditional method to prevent stored grain from deterioration is to control grain temperature.A three dimensional(3-D)numerical model was established to study the temperature variation in outdoor squat silo and large size horizontal warehouse at quasi-steady-state.In this research,porous media model and solar radiation model were adopted.Numerical and experimental results showed that grain temperature was influenced by temperature of wall,height of grain and the distance between grain and the wall.Temperature changes dramatically at the top layer of grain heap due to solar radiation and heat convection at air layer.Temperature of grain close to wall increased with the increasing of ambient temperature.The model established in this research is suitable for predicting grain temperature in outdoor squat silo and large size horizontal warehouse.

关键词： squat silo large size horizontal warehouse porous media model solar radiation model three dimensional numerical model grain temperature quasi-steady-state storage

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Orbits quality and PPP application for Galileo

Orbits quality and PPP application for Galileo

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第九届中国卫星导航学术年会

作者： Guofeng Ji Hang Chang Zhiqiang Yang Xiaolin Jia Liang Zhang College of Geology Engineering and Geomantics Chang'an University National key laboratory of Geographic information Engineering Xi'an Research Institute of Surveying and Mapping

The orbit quality and PPP application of the Galileo precise products from five MGEX analysis centers(AC) are analyzed in this article, the influence of solar Radial Pressure(SRP) model on Precise Orbit Determination(POD) is studied. The results show that: the quality of Galileo orbit from GFZ and TUM is significantly improved if the Cuboid Box-Wing(CBW) priori model is used. The SLR residual amplitudes reduced from 20 cm down to 10 cm, the STD has decreased about 50%, and the mean SLR bias is reduced from-2.06.0 cm to millimeters level;and PHMs clock-offsets daily linear fitting results also show that the periodic signature could be significantly reduced, which is consistent with the results of SLR residuals. CODE’s ECOM2 model shows slightly worse performance than CBW+ECOM1 model, but much better than classic ECOM1 model. In addition, the mean SLR bias of CODE’s and WHU’s orbits is about-2.04.0 cm, too larger than the result of other Analysis Center, so that the impact of albedo model and antenna thrust require appropriate consideration. Precise point positioning(PPP) error of Galileo-only is about 1.0 cm in horizontal, which is very close to the results of GPS-only, but larger than 3.0 cm in vertical component due to the limited number of active satellites. The convergence speed of GPS/Galileo combined solution is faster than any single system, the positioning accuracy in horizontal is improved respect to GPS-only, but a small degradation can be observed in vertical component.

关键词： Galileo system Precise Orbit determination SLR residuals solar radiation model PPP

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