A natural ventilation wind tower with heat pipe heat recovery for cold climates

• Wind towers are normally shut to avoiding heating energy losses during winter.
• Heat pipes were integrated into a multi-directional wind tower to recover heat from exhaust.
• Addition of the heat pipes reduced the air supply rates by up to 8–17%.
• The system met the recommendation (8 L/s/person) for a wind speed of 1 m/s and higher.
• CFD results showed that the system was capable of raising the supply temperature by 4.5 K.

Commercial wind towers are passive ventilation technology based on traditional wind towers of the Middle East. Typical operation of wind towers in cold – mild climates is generally limited to summer-seasons as the outdoor air is too cold to be introduced into spaces for the majority of the year. In addition, the use of natural ventilation solutions has been seen to increase heat loss in buildings and lead to increased energy cost. Wind towers are normally shut down for the sake of avoiding indoor heating energy losses during winter months. Consequently, the concentration of pollutants has seen to rise above the guideline levels, which can lead to ill health. To improve the year-round capabilities of wind towers, a heat recovery system utilising the combination of heat pipes and heat sink was incorporated into a multi-directional wind tower. This study investigates the potential of this concept through the use of numerical analysis and wind tunnel experiments for validation. The findings showed that the wind tower with heat pipes was capable of meeting the required ventilation rates above an inlet air velocity of 1 m/s. In addition to sufficient ventilation, the integration of heat pipes had a positive effect on thermal performance of the wind tower; it raised the supply air by up to 4.5 K. The technology presented here is subject to a patent application (PCT/GB2014/052263).

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