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Wind Tunnel Analysis of the Airflow through Insect-Proof Screens and Comparison of Their Effect When Installed in a Mediterranean Greenhouse
dc.contributor.author | López Martínez, Alejandro | |
dc.contributor.author | Molina Aiz, Francisco Domingo | |
dc.contributor.author | Valera Martínez, Diego Luis | |
dc.contributor.author | Peña Fernández, Ana Araceli | |
dc.date.accessioned | 2020-01-16T08:45:19Z | |
dc.date.available | 2020-01-16T08:45:19Z | |
dc.date.issued | 2016-05-12 | |
dc.identifier.issn | 1424-8220 | |
dc.identifier.uri | http://hdl.handle.net/10835/7334 | |
dc.description.abstract | The present work studies the effect of three insect-proof screens with different geometrical and aerodynamic characteristics on the air velocity and temperature inside a Mediterranean multi-span greenhouse with three roof vents and without crops, divided into two independent sectors. First, the insect-proof screens were characterised geometrically by analysing digital images and testing in a low velocity wind tunnel. The wind tunnel tests gave screen discharge coefficient values of Cd,φ of 0.207 for screen 1 (10 × 20 threads·cm−2; porosity φ = 35.0%), 0.151 for screen 2 (13 × 30 threads·cm−2; φ = 26.3%) and 0.325 for screen 3 (10 × 20 threads·cm−2; porosity φ = 36.0%), at an air velocity of 0.25 m·s−1. Secondly, when screens were installed in the greenhouse, we observed a statistical proportionality between the discharge coefficient at the openings and the air velocity ui measured in the centre of the greenhouse, ui = 0.856 Cd + 0.062 (R2 = 0.68 and p-value = 0.012). The inside-outside temperature difference ΔTio diminishes when the inside velocity increases following the statistically significant relationship ΔTio = (−135.85 + 57.88/ui)0.5 (R2 = 0.85 and p-value = 0.0011). Different thread diameters and tension affects the screen thickness, and means that similar porosities may well be associated with very different aerodynamic characteristics. Screens must be characterised by a theoretical function Cd,φ = [(2eμ/Kpρ)·(1/us) + (2eY/Kp0.5)]−0.5 that relates the discharge coefficient of the screen Cd,φ with the air velocity us. This relationship depends on the three parameters that define the aerodynamic behaviour of porous medium: permeability Kp, inertial factor Y and screen thickness e (and on air temperature that determine its density ρ and viscosity μ). However, for a determined temperature of air, the pressure drop-velocity relationship can be characterised only with two parameters: ΔP = aus2 + bus. | es_ES |
dc.language.iso | en | es_ES |
dc.publisher | MDPI | es_ES |
dc.rights | Attribution-NonCommercial-NoDerivatives 4.0 Internacional | * |
dc.rights.uri | http://creativecommons.org/licenses/by-nc-nd/4.0/ | * |
dc.subject | insect-proof screen | es_ES |
dc.subject | aerodynamic | es_ES |
dc.subject | wind tunnel | es_ES |
dc.subject | greenhouse | es_ES |
dc.subject | microclimate | es_ES |
dc.title | Wind Tunnel Analysis of the Airflow through Insect-Proof Screens and Comparison of Their Effect When Installed in a Mediterranean Greenhouse | es_ES |
dc.type | info:eu-repo/semantics/article | es_ES |
dc.relation.publisherversion | https://www.mdpi.com/1424-8220/16/5/690 | es_ES |
dc.rights.accessRights | info:eu-repo/semantics/openAccess | es_ES |