Análise do impacto do coeficiente de pressão na simulação de ventilação natural em ambientes internos

Abstract

In hot climates, such as those prevalent throughout the Brazilian territory, natural ventilation assumes an important role in thermal comfort. Natural ventilation not only removes thermal load from the buildings, but also assists in the user's evapotranspiration process, contributing to the feeling of comfort. However, natural ventilation processes are not simple, involving complex modeling in simulation software to estimate and verify thermal comfort requirements. This work aimed to compare different estimates of wind pressure coefficients for an educational building: pressure coefficients estimated by EnergyPlus and those obtained through CFD simulation, as well as the respective impacts on the air change rates. To this end, an educational building located in Palmas, TO, which has a complex geometry and natural ventilation solutions, with cobogós, shutters, tilting windows and ventilation ducts in the interior, was studied. The air change rates obtained with the pressure coefficients calculated by EnergyPlus and the null coefficients were applied to the average deviation performance indicator (MBD) to assess the under or overestimation in relation to the air change rates resulting from the simulation with the pressure coefficients obtained by the CFD. The results show that although the behavior of the air change rate curves is similar between the the pressure coefficients of the CFD and the EnegyPlus, the results obtained with the EnergyPlus tend to underestimate the air change rates. From the results it is not recommended for buildings with non-rectangular and / or complex geometry the use of EnergyPlus for the calculation of pressure coefficients, nor the use of null coefficients. Therefore, it is recommended to obtain pressure coefficients through of CFD simulations.