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Natural Ventilation, Wind Effects, Thermal Buoyancy Effects, Turbine Ventilator, Vent Column, Turbine-column Combined Device

Ventilation performance of a curved-blade turbine ventilator, a straight column covered with a flat hat, and a device of their combination of the same material and throat diameter of 21cm were tested on a room model of 3.0m long, 1.5m wide, and 3.0m high under simulated external wind and/or internal heat source. The wind speed was from 0m/s to 3.6m/s. The heat flux was up to 3KW. Air speed through each device was measured and plotted as functions of both the wind speed and the heat flux. The results show that when buoyancy effects were dominant, i.e. internal heat source under low wind speed, the column performed best, followed by the combined device and lastly the turbine. When wind effects were dominant, the combined device worked best, followed by the turbine which was close to the column. Performance of the column was seen to suffer from the external wind while that of the turbine and the combined device benefits from it. Performance of the combined device was found to be better than that of the turbine due to stack effects gained by an increased throat height compared to the turbine’s. This observation suggests a simple modification to boost performance of current commercial low-throat turbine ventilators.