SE—Structures and Environment: AirFlows and Temperature Patterns induced in a Confined Greenhouse
SE—Structures and Environment: AirFlows and Temperature Patterns induced in a Confined Greenhouse
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SE—结构和环境：密闭温室中引起的气流和温度模式
DOI：
10.1006/jaer.2000.0568
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发表时间：
2001
期刊：
影响因子：
--
通讯作者：
A. Jaffrin
中科院分区：
文献类型：
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作者：
M. Lamrani;T. Boulard;J. Roy;A. Jaffrin
摘要在一个缩尺的单跨温室模型中，模拟了典型的单室Rayleigh-Benard对流模式下的二维气流和温度分布。该模块有地板供暖;它保持气密，墙壁绝缘。它的目的是模拟自然对流，在一个真实的连栋温室中，由太阳辐射加热的植物冠层上方产生。温度测量薄热电偶放置在一个静态的网格;气流线确定的可视化技术，激光断层扫描，并通过激光多普勒测速仪的速度测量。在瑞利数为0·8× 1010 ~ 2·3×1010的范围内，观测到稳定的弱湍流区。打破温室对称性的唯一稳定的流动模式是一个大的对流单元，它扫过加热的地板，沿着一个绝缘侧上升，沿着屋顶冷却，并沿着沿着相反侧下降。温度和速度梯度被限制在边界，并且大的静态和均匀的空气核心停留在中心，而不参与热传递。由于限制，对流单元内的实际空气速度比从简单的加热板垂直获得的空气速度大得多。从这个实验中推导出从地板到空气和从空气到屋顶的表观热交换系数，并与文献中发现的全尺寸温室的其他值进行比较。
Abstract Two-dimensional airflows and temperature distributions, corresponding to a typical single-cell Rayleigh–Benard convection pattern, were characterized in a reduced scale, mono-span, greenhouse module. The module has floor heating; it is kept airtight and the walls are insulated. It is designed to simulate free convection, generated above a plant canopy heated by solar radiation, in a real multi-span greenhouse. The temperatures were measured with thin thermocouples placed on a static grid; airflow lines were determined by a visualization technique, laser tomography, and by velocity measurements by laser Doppler anemometry. Stationary, weakly turbulent, regimes were observed for Rayleigh numbers ranging from 0·8×1010to 2·3×1010. The only stable flow pattern, which breaks the symmetry of the greenhouse, is a large convective cell which sweeps the heated floor, rises along one insulated side, cools down along the roof and descends along the opposite side. Temperature and velocity gradients are confined to borders and a large static and homogeneous air core stays at the centre without participating in heat transfer. Due to confinement, actual air velocities inside the convective cell are much larger than those that would be obtained vertically from a simple heated plate. Apparent heat exchange coefficients from the floor to the air and from the air to the roof were deduced from this experiment and compared with other values found in the literature for full-scale greenhouses.