Numerical simulation of natural ventilation with passive cooling by diagonal solar chimneys and windcatcher and water spray system in a hot and dry climate

Abstract

The overuse of fossil fuels has become a major challenge in recent decades. Since mechanical ventilation systems are responsible for the largest proportion of the energy usage in the buildings, this study aims to come up with a green initiative for resolving the dire consequences of energy consumption. Here, for the first time, we work on an approach in which we aim to assess and enhance the evaporative cooling rate of a passive method during a summer day in a multi-story building in a hot and dry climate. In this regard, the windcatcher is coupled with three solar chimneys, and a water spray system (WSS) which is located at the entrance of the windcatcher to decrease the temperature and raise the humidity of the air entering each floor. A combination of wind-catcher, solar chimney, and water spray system is adopted to provide natural air circulation in the absence of wind. Indeed, we employ Radiation, Turbulent, and Discrete Phase Models to simulate the proposed system by CFD. The effect of different variables such as temperature, droplet diameter, and thermal comfort factors are studied. Temperature, velocity, and other airflow profiles are analyzed using ANSYS FLUENT software. The study highlighted that adding WSS leads to a roughly 6–12 °C reduction in the temperature; moreover, relative humidity will rise by 80% on the third floor. Accordingly, adding WSS can improve the system’s efficiency and satisfy the thermal comfort conditions in the absence of wind.