Thermal buoyancy ventilation systems

Abstract

Objectives. To increase the efficiency of natural ventilation systems, it is possible to use the thermal incentives - additional heating of the exhaust ventilation duct, which allows to expand temperature difference between ambient and exhaust air. This method enables stable air exchange in hot period, regardless of wind force. However, existing systems have several limitations to application in multi-storey residential buildings in countries with a cold climate. The main objective of the study is to develop a thermal buoyancy ventilation system, suitable for typical residential building in Russia. Methods. The study of internal natural convection was carried out using the CFD software, based on the finite volume method with unstructured mesh. Results of computer simulation were validated by field experiments. Results. The article presents the results of numerical modelling of natural convection currents arising in the heated channel of the last floor ventilation system in a multi-storey residential building. In the course of the study, there was found the dependence of outlet velocity on temperature difference θ,°C for various heating methods. Conclusions. Using of thermal buoyancy systems with vertical heating provides stable air exchange in the warm and transitional periods of the year. The obtained results illustrate the high level of influence of heating area location on free convection currents in ventilation duct.