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首页> 外文期刊>Journal of Mechanical Science and Technology >Computational fluid dynamics analysis of greenhouse microclimates by heated underground tubes
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Computational fluid dynamics analysis of greenhouse microclimates by heated underground tubes

机译：地下加热管对温室小气候的计算流体动力学分析

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摘要

One of the main problems of Mediterranean climates is the large diurnal amplitude of temperature, with too low temperature during winter nights and too high temperatures during summer days. This is particularly felt in the north of Portugal, where the low temperature during winter nights can be compensated by the introduction of a heat source. The objective of this is work is to simulate the effects in the temperature and velocity fields by the introduction of hot water tubes along a greenhouse in night conditions. Three different situations are simulated: natural convective heating (case A), artificial heating tubes (case B), artificial heating tubes, and natural ventilation (case C). The commercial CFD package ANSYS (FLOTRAN module) is used for this propose. The turbulence is modelled by the RNG turbulence model. The numerical results are compared with experimental values, the procedure for which is also presented. The average increase in air temperature for cases A, B and C was 2.2℃, 6.7℃ and 3.5℃, respectively. Turbulence is lower in case A, increases slightly when the heating system is introduced (case B), and increases significantly in case C due to the effect of natural ventilation. A very good agreement between experimental and numerical temperature values was verified. This allows validating the RNG turbulence model as suitable to simulate arch-shaped greenhouse microclimates. Some improvements can be done to this work: introduction of night-time crop transpiration, 3D simulations, or optimizing the size of the element mesh in order to reduce the computation time.
机译：地中海气候的主要问题之一是温度的昼夜幅度大，冬季夜晚温度太低，夏季白天温度太高。在葡萄牙北部尤为如此，那里的冬季夜晚的低温可以通过引入热源来弥补。这项工作的目的是通过在夜间沿着温室沿温室引入热水管来模拟温度和速度场中的影响。模拟了三种不同情况：自然对流加热（情况A），人工加热管（情况B），人工加热管和自然通风（情况C）。商业CFD软件包ANSYS（FLOTRAN模块）用于此建议。湍流由RNG湍流模型建模。将数值结果与实验值进行比较，并给出了过程。 A，B和C病例的平均气温升高分别为2.2℃，6.7℃和3.5℃。在情况A中，湍流较低，在引入加热系统时（情况B），湍流略有增加;在情况C中，由于自然通风的影响，湍流明显增加。实验和数值温度值之间的很好的一致性被证实。这允许验证适合模拟拱形温室微气候的RNG湍流模型。可以对这项工作进行一些改进：引入夜间作物蒸腾，3D模拟或优化元素网格的大小以减少计算时间。

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