Use of Coanda nozzles for double glazed facades forced ventilation

摘要

Fans are the most widespread system used to implement forced convection ventilation for double glazed facades (DGF). However, the implementation of fans in a facade require an electrical supply for the motors, solid supports for the fans, and the installation has to meet fire safety regulations required by local laws. These facts, added to the need of a regular maintenance program for the fans and the possibility of noise and vibration generated by the moving parts of these equipment, might increase the final cost of the facade and reduce the comfort inside the building. In this paper the feasibility of using nozzles for DGF ventilation is evaluated. The nozzles selected for this study are based on the Coanda effect. For this investigation, a CFD model was used to simulate a Coanda nozzle. The modeled nozzle was simulated for different flow rate conditions and velocity and pressure fields obtained in the nozzle outlet were imposed as an inlet boundary condition in an upper crossed lateral ventilation model for a DGF. Results obtained for heat flux, and reductions in solar gain loads for different operating conditions were obtained and compared against previous results for vertical and horizontal DGF ventilation in a similar geometry.