Studies of ventilation and thermal comfort in different wind tower-room configurations considering humidification for a warm climate of Mexico

Abstract

Air conditioning systems in buildings demand a high energy consumption and will only be exacerbated by the threat of climate change, as coping with the increased temperatures will require a higher consumption of electricity for ventilation and cooling. The use of passive techniques to save energy and provide thermal comfort inside the buildings should be a priority for research. This work investigates the effectiveness of the passive natural ventilation system called the wind tower (windcatcher) to provide thermal comfort in a room without and with air humidification, for warm climatic conditions. The study was carried out using CFD considering three-dimensional turbulent flow for the continuous phase and a Lagrangian approach for the discrete phase. In addition, the parameters and indices of natural ventilation and thermal comfort were calculated. 54 different configurations of the wind tower and the room outlet window were evaluated. The influence of a chamfer in the tower and the optimization of water consumption in the humidifier were also investigated. The results showed that the selection of a suitable configuration and the use of a chamfer, can substantially improve ventilation and thermal comfort. In addition, the optimal mass flow rate for humidification that provides a sensation of neutral thermal comfort and minimal water consumption was found. The use of a wind tower and the application of humidification at the critical hours of the day, will provide thermal comfort throughout the day with a predicted percentage of dissatisfied lower than 10%. These results show that low energy consuming systems utilizing natural ventilation and air humidification in a wind tower-room system can be sufficient for appropriate cooling and thermal comfort.