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Three-dimensional computational fluid dynamics analysis of buoyancy-driven natural ventilation and entropy generation in a prismatic greenhouse

Aich Walid (Haïl University, College of Engineering, Haïl City, Saudi Arabia + University of Monastir, Ecole Nationale d’Ingénieurs, Unité de Recherche de Métrologie et des Systèmes Energétiques, Monastir, Tunisia)
Kolsi Lioua (Haïl University, College of Engineering, Haïl City, Saudi Arabia + University of Monastir, Ecole Nationale d’Ingénieurs, Unité de Recherche de Métrologie et des Systèmes Energétiques, Monastir, Tunisia)
Borjini Mohamed N. (University of Monastir, Ecole Nationale d’Ingénieurs, Unité de Recherche de Métrologie et des Systèmes Energétiques, Monastir, Tunisia)
Al-Rashed Abdullah A.A.A. (College of Technological Studies, the Public Authority for Applied Education and Training, Department of Automotive and Marine Engineering Technology, Adailiyah, Kuwait)
Aissia Habib Ben (University of Monastir, Ecole Nationale d’Ingénieurs, Unité de Recherche de Métrologie et des Systèmes Energétiques, Monastir, Tunisia)
Oztop Hakan F. (Firat University, Technology Faculty, Department of Mechanical Engineering, Elazig, Turkey + King Abdulaziz University, Department of Mechanical Engineering, Jeddah, Saudi Arabia)
Abu-Hamdeh Nidal (King Abdulaziz University, Department of Mechanical Engineering, Jeddah, Saudi Arabia)

A computational analysis of the natural ventilation process and entropy generation in 3-D prismatic greenhouse was performed using CFD. The aim of the study is to investigate how buoyancy forces influence air-flow and temperature patterns inside the greenhouse having lower level opening in its right heated façade and also upper level opening near the roof top in the opposite cooled façade. The bot-tom and all other walls are assumed to be perfect thermal insulators. Rayleigh number is the main parameter which changes from 103 to 106 and Prandtl number is fixed at Pr = 0.71. Results are reported in terms of particles trajectories, iso-surfaces of temperature, mean Nusselt number, and entropy generation. It has been found that the flow structure is sensitive to the value of Rayleigh number and that heat transfer increases with increasing this parameter. Also, it have been noticed that, using asymmetric opening positions improve the natural ventilation and facilitate the occurrence of buoyancy induced upward cross air-flow (low-level supply and upper-level extraction) inside the greenhouse.

Keywords: 3-D CFD, natural ventilation, prismatic greenhouse, heat transfer, entropy generation