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In buildings, 60% of energy consumption is associated to HVAC systems. One solution to reduce this share is the application of natural ventilation systems. Windcatcher and wing wall are two well-known techniques for natural ventilation which have been used in different regions. Nevertheless, in areas with low wind speed such as tropical climate of Malaysia there is hesitation for application of natural ventilation systems. The integration of windcatcher with wing wall can potentially enhance the ventilation performance. However, this configuration was not looked into by pervious investigations; thus, this study aims to address this gap of research by evaluating: first, the effect of wing wall angle on the ventilation performance; second, comparethe performance of this new design with a conventional windcatcher. This research had two main investigative steps: experimental scaled wind tunnel testing and CFD simulation. Four reduced-scale models of two-sided windcatcher were tested in a low speed wind tunnel. Three models were integrated with wing wall in 30°, 45° and 60° incident angles and the another windcatcher was a conventional two-sided windcatcher, which is typical in regions with predominant wind direction. The CFD validation against experiment showed a good agreement. The best operation was observed in the windcatcher with 30° wing wall angle which could supply 910 l/s fresh air into the room in 2.5 m/s wind speed. Hence, the new design had 50% more ventilation performance comparing with conventional two-sided windcatcher in the same external wind speed. Finally, it was concluded that this new design can satisfy requirements of ASHRAE 62.1.

Abstract:Global demand for energy continues to increase rapidly, due to economic and population growth, especially for increasing market economies. These lead to challenges and worries about energy security that can increase as more users need more energy resources. Also, higher consumption of fossil fuels leads to more greenhouse gas emissions, which contribute to global warming. Moreover, there are still more people without access to electricity. Several studies have reported that one of the rapidly developing source of power is wind energy and with declining costs due to technology and manufacturing advancements and concerns over energy security and environmental issues, the trend is predicted to continue. As a result, tools and methods to simulate and optimize wind energy technologies must also continue to advance. This paper reviews the most recently published works in Computational Fluid Dynamic (CFD) simulations of micro to small wind turbines, building integrated with wind turbines, and wind turbines installed in wind farms. In addition, the existing limitations and complications included with the wind energy system modelling were examined and issues that needs further work are highlighted. This study investigated the current development of CFD modelling of wind energy systems. Studies on aerodynamic interaction among the atmospheric boundary layer or wind farm terrain and the turbine rotor and their wakes were investigated. Furthermore, CFD combined with other tools such as blade element momentum were examined. Keywords:Computational Fluid Dynamic (CFD); micro to small wind turbine; building integrated with wind turbine; wind farm; aerodynamic interaction; wind energy systems; atmospheric boundary layer (ABL); blade element momentum (BEM)

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