Numerical-experimental study of mixed convection in a wind tower-room system

Abstract

Passive strategies are employed in buildings to minimize their total energy consumption and emissions of CO2. The wind tower (windcatcher) is a traditional natural ventilation device capable of reducing building energy consumption and improving the indoor environment. In this work, the performance of the mixed convection in a wind tower-room system is studied, considering natural convection by differential heating in the room and forced convection by the wind entering the tower. A parametric analysis has been carried out considering different values of velocities, temperatures, and relative humidity of the air. Different room wall temperatures were also considered. Ri number studied in this work was in the range of 6.6 × 10−2 and 1.5 × 102. An experimental study was also carried out to validate the numerical results. Comparison numerical-experimental results indicate a mean bias error of 0.49 °C for temperature and a percentage deviation of 24.4% for air velocity. The results showed that the wind tower achieves sensation-neutral comfort inside the room when outside temperatures are between 25 and 30 °C. Regarding Ri numbers lower than 1, the air exchange effectiveness is partially constant, while it can vary by 31% for Ri values greater than 1. The results also indicated that for Ri numbers lower than 1, the heat transfer is 71% greater than for Ri values greater than 1. The findings provided in this paper could contribute to a better understanding of the performance of mixed convection in rooms of buildings with a wind tower.