Wind tunnel test and numerical study of a multi-sided wind tower with horizontal heat pipes

Abstract

Passive ventilation such as wind towers can ventilate spaces by using regional pressure differences and the stack effect. Wind towers are often closed throughout the winter to prevent an increase in heating energy demand. Heat pipes can be installed to transfer heat from the outgoing to the incoming air, however the inclusion of heat recovery can incur a pressure drop that negatively impacts ventilation rates. Here it is shown that with an array of horizontally arranged heat pipes, ventilation rates of 0.1 m3/s are maintained at a 1 m/s inlet velocity. The incoming air temperature was raised by up to 2.8 °C, thereby increasing the operational window of the passive ventilation system. By mounting the heat pipes horizontally through the wind tower, direct heat transfer is facilitated between the inlet and outlet. The results demonstrate how a passive ventilation and heat recovery system is likely to operate in the winter months of a cooler climate according to the wind speed and temperature difference between the fresh and exhaust air. It is intended that this system will be further developed to provide both heating and cooling in the winter and summer respectively by installing a seasonal thermal loop.