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大跨度保温型温室是针对日光温室之间南北间距较大,土地利用效率不高而设计的。该温室可将日光温室南北间距缩减为2m以内,同时具有日光温室的良好保温特征,但一直以来缺乏对该大跨度保温型温室的光温性能评价。本研究利用计算流体力学软件(Computational fluid dynamics,CFD)构建三维稳态温室模型,模拟不同走向对温室光温环境的影响,为温室建设提供理论依据。在模型中采用太阳射线追踪法加载太阳辐射,通过离散坐标辐射模型(Discrete ordinates,DO)模拟热辐射的影响。将模拟结果与试验测量结果进行对比,模型模拟值与实测值绝对偏差在0.3~2.1℃范围内,验证了构建的CFD温室模型的准确性。利用已验证的模型模拟结构尺寸完全相同,走向分别为东西与南北的2栋温室内的温度场分布情况,比较分析不同时刻(6个案例)温室内温度场差别。模拟结果表明,在上午10:00和下午14:00,2种走向温室内温度差异不明显在正午12:00,南北走向温室内温度比东西走向温室高2.8℃。在室温分布均匀性方面,利用CFD后处理软件提取6个案例在每一节点处的模拟值,统计6个案例温室温度的相对标准偏差,结果表明,在早、中、晚的3个时间段内,南北走向温室的RSD值均低于东西走向温室。综合模拟与测试结果表明,双拱大跨度保温型温室在北方地区应选用南北走向,温室的光照分布、温度分布都优于东西走向。
Long-span thermal insulation greenhouse is designed for sunlight greenhouse large spacing between north and south, land use efficiency is not high. The greenhouse can reduce the space between the north and south of the greenhouse to within 2m, and has good insulation characteristics of the greenhouse at the same time. However, the evaluation of the light and temperature of the greenhouse with large-span has not always been evaluated. In this study, Computational fluid dynamics (CFD) software was used to build a three-dimensional steady-state greenhouse model to simulate the impact of different trends on the light and temperature environment in the greenhouse, providing a theoretical basis for greenhouse construction. The solar radiation was loaded by solar ray tracing method in the model, and the influence of thermal radiation was simulated by Discrete ordinates model (DO). The simulation results are compared with the experimental measurement results. The absolute deviation between simulated and measured values is in the range of 0.3 ~ 2.1 ℃, which verifies the accuracy of the constructed CFD greenhouse model. The verified model was used to simulate the distribution of temperature field in two greenhouses with east-west, south-north and north-west structures respectively. The differences of temperature field in different time (six cases) were analyzed. The simulation results show that at 10:00 am and 14:00 pm, the difference in temperature between the two kinds of greenhouses is not obvious at 12:00 noon, and the temperature in the south and the north toward the greenhouse is 2.8 ° C higher than the east and west greenhouses. In terms of the uniformity of room temperature distribution, the simulated values of 6 cases at each node were extracted by CFD postprocessing software, and the relative standard deviations of greenhouse temperature in 6 cases were calculated. The results showed that during the early, middle and late periods The RSD values of the interior and exterior greenhouses are lower than those of the east and west greenhouses. The results of the comprehensive simulation and test show that the long-span double-arch insulation greenhouse should be north-south in the northern region. The light distribution and temperature distribution in the greenhouse are superior to the east-west trend.