temperature differences range from 2.0 to 6.1 °C. In a study with tomatoes,
Majdoubi et al. (2007) found that crop rows oriented perpendicular to air movement reduce the rate of airflow through the cultivation in a greenhouse by 50 %.
According to Baeza et al. (2008), a greenhouse with natural ventilation efficiency
must combine a sufficient number of air changes to remove excess heat, with good
circulation of air through the crop. The effect of the crop was evaluated by Impron
et al. (2007) by using a sub-model to determine the effects of ventilation, the
properties of the cover, and crop transpiration. In agreement with Kruger and
Pretorius (2007), the temperature and velocity at the plant level are influenced by
the arrangement and number of windows. A study carried out by Sapounas et al.
(2007) simulated a tomato crop as a porous medium, taking into account the
addition of buoyancy to develop a model of the pressure drop of airflow due to the
crop. The model depended on the area of leaf stage growth and cultivation, under
the RANS turbulence model in conjunction with the RNG k-e turbulence model.
The results, validated with experimental measurements obtained at 1.2 m in the
canopy, show that the evaporative cooling system is effective with numerical
parameters, providing a useful tool to improve system efficiency. A study by Roy
et al. (2008) on leaf level through an experimental setup based on Münger cells
measured the temperature, relative humidity, and different heat flows to the leaves
of soybeans, obtaining minimum stomatal resistance values ranging from 66 to
200 sm
-1 .
Teitel et al. (2008) built a small-scale model and found that wind direction
significantly affects the ventilation rate and temperature distribution in crops. A
study by von Elsner et al. (2000) on the effect of near-infrared (NIR) reflecting
pigments in microclimate and plant growth found that a temperature drop up to
4 °C in a young crop is the result of a 18 % reduction in the transmission of global
radiation in spring. At the same time, during the rainy season, minimizing transpiration differences in temperature and shading reduces water requirements in the
plants, and they observed parthenocarpic fruit rot and yield-reducing crop. In a
tunnel-type greenhouse, a tomato crop was modeled by Bartzanas et al. (2008) by
designing a porous medium, where they emphasize the influence of the heating
system on greenhouse microclimate. The climatic behavior of the rows of the
tomato crop is taken into account using external user defined functions (Baxevanou et al. 2008). According to Majdoubi et al. (2009), reorienting crop rows in
simple ways improved climatic conditions. Endalew et al. (2009) performed CFD
modeling of a plant with leaves and branches of the canopy, using turbulent energy
equations in porous sub-domains created around the branches. Fidaros et al. (2010)
simulated a greenhouse tomato crop as a porous medium to model radiation
transport by discrete ordinates (DO). According to Teittel (2010), when applying
the porous medium approach, the Forchheimer equation is often used, which can
cause erroneous results with respect to the pressure drop through screens. An
alternative way to calculate it through several panels of porous media used to
simulate screens with realistic geometries. Moreover, the crop exerts a mechanical
strain (drag force) on the flow just above but also interacts through the transpiration process with the temperature and humidity distributions (Bournet and
354
G. De la Torre-Gea et al.
Majdoubi et al. (2007) found that crop rows oriented perpendicular to air movement reduce the rate of airflow through the cultivation in a greenhouse by 50 %.
According to Baeza et al. (2008), a greenhouse with natural ventilation efficiency
must combine a sufficient number of air changes to remove excess heat, with good
circulation of air through the crop. The effect of the crop was evaluated by Impron
et al. (2007) by using a sub-model to determine the effects of ventilation, the
properties of the cover, and crop transpiration. In agreement with Kruger and
Pretorius (2007), the temperature and velocity at the plant level are influenced by
the arrangement and number of windows. A study carried out by Sapounas et al.
(2007) simulated a tomato crop as a porous medium, taking into account the
addition of buoyancy to develop a model of the pressure drop of airflow due to the
crop. The model depended on the area of leaf stage growth and cultivation, under
the RANS turbulence model in conjunction with the RNG k-e turbulence model.
The results, validated with experimental measurements obtained at 1.2 m in the
canopy, show that the evaporative cooling system is effective with numerical
parameters, providing a useful tool to improve system efficiency. A study by Roy
et al. (2008) on leaf level through an experimental setup based on Münger cells
measured the temperature, relative humidity, and different heat flows to the leaves
of soybeans, obtaining minimum stomatal resistance values ranging from 66 to
200 sm
-1 .
Teitel et al. (2008) built a small-scale model and found that wind direction
significantly affects the ventilation rate and temperature distribution in crops. A
study by von Elsner et al. (2000) on the effect of near-infrared (NIR) reflecting
pigments in microclimate and plant growth found that a temperature drop up to
4 °C in a young crop is the result of a 18 % reduction in the transmission of global
radiation in spring. At the same time, during the rainy season, minimizing transpiration differences in temperature and shading reduces water requirements in the
plants, and they observed parthenocarpic fruit rot and yield-reducing crop. In a
tunnel-type greenhouse, a tomato crop was modeled by Bartzanas et al. (2008) by
designing a porous medium, where they emphasize the influence of the heating
system on greenhouse microclimate. The climatic behavior of the rows of the
tomato crop is taken into account using external user defined functions (Baxevanou et al. 2008). According to Majdoubi et al. (2009), reorienting crop rows in
simple ways improved climatic conditions. Endalew et al. (2009) performed CFD
modeling of a plant with leaves and branches of the canopy, using turbulent energy
equations in porous sub-domains created around the branches. Fidaros et al. (2010)
simulated a greenhouse tomato crop as a porous medium to model radiation
transport by discrete ordinates (DO). According to Teittel (2010), when applying
the porous medium approach, the Forchheimer equation is often used, which can
cause erroneous results with respect to the pressure drop through screens. An
alternative way to calculate it through several panels of porous media used to
simulate screens with realistic geometries. Moreover, the crop exerts a mechanical
strain (drag force) on the flow just above but also interacts through the transpiration process with the temperature and humidity distributions (Bournet and
354
G. De la Torre-Gea et al.