Effects of ventilator configuration on the flow pattern of a naturally-ventilated three-span Mediterranean greenhouse

Study of natural ventilation in a Gothic multi-tunnel greenhouse designed to produce rose (Rosa spp.) in the high-Andean tropic

“…Ventilation rates (Φ, m 3 m -2 s -1 ) for each evaluated configuration were calculated (Figure 4). The values obtained from Φ for RSV range from 0.044 y 0.182 m 3 m -2 s -1 for RSVV1 and RSVV4 respectively, this ventilation configuration is the one with the highest values from Φ which is in line with previous studies carried out in tunnel greenhouses (Espejel Trujano and López Cruz, 2013;He et al, 2015). For SV and RV it was found that the average reduction values of Φ are in the order of 33.45% and 50.5% respectively, with minimum values of 20% and 45% for SVV4 and RVV2, which confirms the importance of side ventilation for outdoor air velocities higher than 1.5 m s -1 while roof-top ventilation becomes relevant at air velocities lower than 1 m s -1 , due to the contribution of the thermal effect to the natural ventilation (Katsoulas et al, 2006).…”

“…The turbulent nature of the airfl ow was simulated using the standard turbulence model k-ε with standard wall functions, this model has been widely used and validated in natural greenhouse ventilation studies (Teitel andWenger, 2014: Bournet et al, 2017). The buoyancy effects infl uenced by the change in air density will be present (Espinal-Montes et al, 2015) and can be modeled through the Bousinessq model, which is described by the following expression:…”

CFD Simulation of the Increase of the Roof Ventilation Area in a Traditional Colombian Greenhouse: Effect on Air Flow Patterns and Thermal Behavior

“…For the reference scenario S1 it can be observed that the values of Φ ranged between 0.0085 and 0.067 m 3 m -2 s -1 for V1 and V5, as previously demonstrated in multiple studies, the dependence of the ventilation rate on wind speed is linear, under these results it can be clearly identified that the ventilation rates for the dominant speeds in the study region V1, V2 and V3, are below the recommended minimum value of Φ = 0.04 m 3 m -2 s -1 . It is also perceptible that as the roof ventilation area is increased, an increase in ventilation rates is generated for each scenario compared to S1, obtaining ventilation rates with a higher mean value of 52, 78, 97, 118, 150 and 191 % for S2 to S7 respectively, which allows to verify that the ventilation rate is also highly dependent on the ventilation configuration and the arrangement of ventilators used in the greenhouse, as previously demonstrated in several studies and more recently in the one developed by Espinoza et al [11].…”

“…Natural ventilation is highly dependent on external meteorological variables such as wind speed, intensity and direction, greenhouse design factors such as roof geometry, greenhouse area and volume, and size and location of ventilation areas. According to the above, natural ventilation varies over daytime generating sometimes an inadequate microclimate condition inside the greenhouse [10,11]. The CTG greenhouse is generally located in regions with low wind speeds and its ventilation areas are less than the recommended figure of being at least 25 % of the covered ground area [12].…”

Protected Cropping in Warm Climates: A Review of Humidity Control and Cooling Methods

“…They used CFD modelling to study different vent-opening strategies on natural ventilation and suggested specific control approaches that consider wind speed and direction as the input. Espinoza et al [85] studied the effect of ventilator configuration on the flow pattern in a Mediterranean greenhouse with obstacles to air flow (surrounding greenhouses). The ventilation rate was affected by ventilator distribution and obstruction to ventilation systems.…”