Effect of material ageing and dirt on the behaviour of greenhouse insect-proof screens
| Autor: | Karlos Espinoza, F.D. Molina-Aiz, Alejandro López, Araceli Peña, Diego L. Valera |
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| Přispěvatelé: | Spanish Ministry of Economy and Competitiveness and European Regional Development Fund (ERDF) (grant AGL2015-68050-R) |
| Jazyk: | angličtina |
| Rok vydání: | 2019 |
| Předmět: |
Pressure drop coefficient
Airflow Agricultural engineering lcsh:S Environmental engineering Greenhouse Dirt Natural ventilation Discharge coefficient lcsh:Agriculture anti-insect screens aerodynamic characterisation accumulation of dust and dirt deterioration Environmental science Porosity Agronomy and Crop Science Wind tunnel |
| Zdroj: | Spanish Journal of Agricultural Research; Vol 16, No 4 (2018); e0205 Spanish Journal of Agricultural Research; Vol. 16 No. 4 (2018); e0205 Spanish Journal of Agricultural Research; Vol. 16 Núm. 4 (2018); e0205 SJAR. Spanish Journal of Agricultural Research instname Spanish Journal of Agricultural Research, Vol 16, Iss 4, Pp e0205-e0205 (2019) |
| ISSN: | 2171-9292 |
| Popis: | The present work examines the variations in the aerodynamic characteristics of four insect-proof screens by means of wind tunnel tests and digital image processing. The tested insect-proof screens were examined in three different conditions: (i) in their new, unused state; (ii) under conditions of accumulated dust and dirt after a period of 3 to 4 years of use; and (iii) under clean conditions after a period of 3 to 4 years of use and a cleaning treatment with high-pressure water. The deterioration of the screens caused the mesh to become less tense, therefore increasing its thickness and improving its aerodynamic behaviour despite a slight increase of the thread diameter and a subsequent decrease of the 2-dimensional porosity. The pressure drop coefficient, F φ , of the used but clean screens was 1.5% to 8.8% lower (for u =1.0 m/s) than that of the new ones, thus increasing the discharge coefficient, C d,φ , by between 0.8% and 4.8% as a result of the presence of the screens. On the other hand, comparison of the used screens in their clean and unclean states showed that the accumulation of dirt has a major bearing on their aerodynamic characteristics: F φ increased by between 16.5% and 61.2% (for u =1.0 m/s) for the unclean screens, resulting in a C d,φ reduction of between 7.5% and 21.3% and therefore a lower natural ventilation capacity of the greenhouse. A regular cleaning treatment of the insect-proof screens is a simple measure that improves the natural ventilation capacity of the greenhouse. |
| Databáze: | OpenAIRE |
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