Articles
ANALYSIS OF THE EFFECT OF ROLLUP VENT ARRANGEMENT AND WIND SPEED ON ALMERÍA-TYPE GREENHOUSE VENTILATION PERFORMANCE USING COMPUTATIONAL FLUID DYNAMICS
Article number
719_17
Pages
173 – 180
Language
English
Abstract
The effects of four greenhouse vent configurations and two external wind speeds on ventilation rates and temperature distributions in an empty Almería-type greenhouse were investigated.
Optimisation of the traditional vent configuration of a five-span greenhouse for better air renewal was attempted by two-dimensional numerical simulations using a computational fluid dynamics (CFD) approach.
The aim of the study was to evaluate the effects of two roof vent sizes on ventilation, in order to recommend the optimal design to growers and greenhouse manufacturers.
Three arrangements of side vents were also considered: a 0.75 m high rollup window placed from 0.25 to 1.0 m above the ground, a vent located from 0.85 to 1.6 m and a 1.5 m high vent starting at 0.1 m from the ground.
The CFD calculations had been previously verified against experimental results.
The ventilation configuration affected the air flow, the ventilation rate and the air temperature distribution in the greenhouse.
For the different configurations, computed air flow varied from 70.1 to 134.9 m3 s1, for an outside wind speed of 5 m s1 (21.0 to 43.3 m3 s1 for 1 m s1), and for a wind direction perpendicular to the openings.
Likewise, the simulations highlighted that while the mean air temperature at the middle of the greenhouse varied from 28.2 to 32.9ºC for an outside air temperature of 26ºC, there were regions inside the greenhouse which were 13ºC warmer than the outside air.
Optimisation of the traditional vent configuration of a five-span greenhouse for better air renewal was attempted by two-dimensional numerical simulations using a computational fluid dynamics (CFD) approach.
The aim of the study was to evaluate the effects of two roof vent sizes on ventilation, in order to recommend the optimal design to growers and greenhouse manufacturers.
Three arrangements of side vents were also considered: a 0.75 m high rollup window placed from 0.25 to 1.0 m above the ground, a vent located from 0.85 to 1.6 m and a 1.5 m high vent starting at 0.1 m from the ground.
The CFD calculations had been previously verified against experimental results.
The ventilation configuration affected the air flow, the ventilation rate and the air temperature distribution in the greenhouse.
For the different configurations, computed air flow varied from 70.1 to 134.9 m3 s1, for an outside wind speed of 5 m s1 (21.0 to 43.3 m3 s1 for 1 m s1), and for a wind direction perpendicular to the openings.
Likewise, the simulations highlighted that while the mean air temperature at the middle of the greenhouse varied from 28.2 to 32.9ºC for an outside air temperature of 26ºC, there were regions inside the greenhouse which were 13ºC warmer than the outside air.
Publication
Authors
F.D. Molina-Aiz, D.L. Valera, A.A. Pena, A.J. Alvarez, J.A. Gil
Keywords
Finite Elements Method, airflow, modelling, insect-proof screens, greenhouse design, optimization
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