Integration and application of passive cooling within a wind tower

Abstract

Increasing emphasis on reducing power consumption has raised public awareness of natural and renewable energy resources, particularly the integration of passive cooling systems in buildings such as wind towers. Wind towers have been in existence in various forms for centuries as a non-mechanical means of providing indoor ventilation. In hot conditions where there is a relatively low difference between internal and external temperatures, the cooling capabilities of wind towers which depend mainly on the structure design itself are inadequate. Therefore it is essential to cool the air in order to reduce the building heat load and improve the thermal comfort of its occupants during the summer months. The aim of this work was to incorporate heat transfer devices in a wind tower to meet the internal comfort criteria in extreme external conditions. Heat transfer devices were installed inside the passive terminal of the 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. Computational Fluid Dynamics (CFD) modelling and experimental wind tunnel testing were conducted to investigate the performance of a wind tower system incorporating the heat transfer device arrangement. Results have indicated that the achieved indoor air speed was reduced by 28-52 % following the integration of the heat transfer device configurations. Furthermore, the study concluded that the proposed cooling system was capable of reducing the air temperatures by up to 12 K, depending on the configuration and operating conditions. Good agreement was observed between the CFD simulation and the experimental results.