Diffusion Characteristics of Solar Beams Radiation Transmitting through Greenhouse Covers in Arid Climates

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

Energies, 2020, vol. 13, issue 2, 1-15

Abstract: In hot and sunny regions, extensive solar radiation transmitted into greenhouses makes it essential to select a greenhouse cover with specific characteristics. Reflection and diffusion are the most important properties of covers for reducing solar heating load and scattering solar beams for better growth of plants. Three types of plastic films that are commonly used for covering greenhouses in arid climate were selected for this study. These were reflective-diffusive ( RDF ), diffusive ( DF ), and locally produced ( CF ) films. The films were used to cover three identical twin-span greenhouse models; the radiation components, air temperature ( T i ), and relative humidity ( RH i ) were measured in each model. Transmission of solar radiation through each cover was characterized by determining: (i) The beam that is diffused during transmission, and (ii) the unscattered beam that is transmitted directly through the film. The results show that the diffuse radiation transmitted through the DF , RDF , and CF covers was enhanced, respectively by 77%, 85%, and 109% as a result of diffusing 34%, 33%, and 43% of the transmitted beam radiation by the DF , RDF , and CF covers, respectively during transmission. The diffusive nature of the tested covers increased the ratio of diffuse to direct beam radiation ( D/B ) from 0.3 outside the greenhouse to 0.77, 0.69, and 0.95 inside a greenhouse covered with DF , RDF , and CF , respectively. At around noon, the CF cover decreased T i by about 5–10 °C and increased RH i by about 3%–5% compared to those under the DF and RDF covers. However, DF and RDF covers showed almost similar effects in T i and RH i . The low-price CF cover showed higher diffusive-radiative properties than DF and RDF covers and can serve effectively in arid climate as an alternative covering material.

Keywords: greenhouse; plastic film; solar beam radiation; transmission; diffusion; reflection (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: 2020
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (1)

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