Integration and application of passive cooling within a wind tower

The aim of this work was to combine low energy heat transfer devices with a passive ventilation terminal to meet the internal comfort criteria in extreme external conditions using non-mechanical means. Heat transfer devices were installed inside the passive terminal of a wind tower unit, highlighting the potential to achieve minimal restriction in the external air flow stream while ensuring maximum contact time, thus optimising the cooling duty of the device. A numerical analysis was conducted using Computational Fluid Dynamics (CFD) software to simulate and analyse the air flow pattern, pressure and temperature distribution around and through the wind tower to a test room. Experimental investigations were carried out using a closed-loop subsonic wind tunnel at 1:10 scale to assess the accuracy of the simulation results. Pressure coefficients distribution, internal air speed and volumetric airflow were measured for a range of external conditions. Smoke visualisation testing enabled the detailed study and analysis of the air flow patterns in and around the wind tower models for different air incident angles.
The proposed cooling system was capable of reducing the air temperatures up to 15 K, depending on the configuration and operating conditions. Initial findings revealed that height was not a factor for the proposed heat transfer device arrangement, making it highly viable for commercial roof-mounted wind tower systems. Another advantage of the proposed system over the traditional evaporative cooling systems was the non-reliance on the constant supply of water to continue the cooling cycle.
In addition, four-sided and one-sided wind towers were utilised as benchmarks for the CFD investigations. Two heat transfer device (HTD) configurations were incorporated in the wind tower models namely vertical and horizontal HTD arrangements. Furthermore, the CFD model was also used to investigate the effect of the addition of extended surfaces and porous media on the thermal performance of the cooling wind tower.
The thermal environment of the test room equipped with a heat transfer device cooling wind tower was simulated and evaluated using Fluent Airpak. The thermal comfort was studied using the PMV index scale. The elements necessary to calculate the PMV and PPD were taken from the initial CFD and experimental results.