Predicting the Cooling Potential of Different Shading Methods for Greenhouses in Arid Regions

Ahmed Abdel-Ghany, Ibrahim Al-Helal, Fahad Alkoaik, Abdullah Alsadon, Mohamed Shady and Abdullah Ibrahim
Additional contact information
Ahmed Abdel-Ghany: Department of Agricultural Engineering, College of Food and Agriculture Sciences, King Saud University, P.O. Box 2460, Riyadh 11451, Saudi Arabia
Ibrahim Al-Helal: Department of Agricultural Engineering, College of Food and Agriculture Sciences, King Saud University, P.O. Box 2460, Riyadh 11451, Saudi Arabia
Fahad Alkoaik: Department of Agricultural Engineering, College of Food and Agriculture Sciences, King Saud University, P.O. Box 2460, Riyadh 11451, Saudi Arabia
Abdullah Alsadon: Department of Plant Production, College of Food and Agriculture Sciences, King Saud University, P O Box 2460, Riyadh 11451, Saudi Arabia
Mohamed Shady: Department of Agricultural Engineering, College of Food and Agriculture Sciences, King Saud University, P.O. Box 2460, Riyadh 11451, Saudi Arabia
Abdullah Ibrahim: Department of Plant Production, College of Food and Agriculture Sciences, King Saud University, P O Box 2460, Riyadh 11451, Saudi Arabia

Energies, 2019, vol. 12, issue 24, 1-13

Abstract: Shading greenhouses in a hot and sunny climate is essential to reduce the inside greenhouse air temperature. However, the type and location of nets need to be addressed properly to determine the shading method that provides a better cooling effect on the greenhouse air. This study was conducted to evaluate the effects of five different shading methods on greenhouse microclimates, and to investigate the cooling potential of each method. Four greenhouse models covered with 200-µm thick plastic film were used for the study: one was kept as control (C), one was whitened with slaked lime (L), and two were shaded with white and black nets (50% shading factor) deployed simultaneously at two locations, in contact (WC, BC) and at 20-cm distance from the cladding film (WD, BD). The microclimatic parameters were measured inside and outside the greenhouse models, and the cooling potential (CP) was predicted for each shading method. The results showed that the black net at 20-cm distance (BD) is desirable as it provides high CP with a reasonable solar radiation transmission. The maximum CP was estimated as 8.5 °C, 8 °C, 6 °C, 3.2 °C, and 2.1 °C for L, BD, BC, WD, and WC, respectively. Shading with white nets is not recommended because their cooling potential is very low. Based on these results, we developed correlations for predicting the CP for each shading method as a function of the transmitted solar radiation flux ( S i ). These correlations depend on S i . Accordingly, they can be used for small greenhouses, whitewashed with a slaked lime of any concentration, or shaded with a black net having any shading factor.

Keywords: shading nets; solar radiation; heating; cooling; greenhouse; hot regions (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2019
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (1)

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