ESAV - DIA - Resumos de eventos científicos não indexados à WoS/Scopus
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Browsing ESAV - DIA - Resumos de eventos científicos não indexados à WoS/Scopus by Subject "Air curtain"
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- Empirical correlation to estimate the optimum jet velocity of an air curtainPublication . Goncalves, J. C.; Costa, José; Figueiredo, A. Rui; Lopes, AntónioThis paper presents the results of a parametric study to quantify the influence of some thermal and geometrical parameters (door height) on the performance of an Air Curtain Device (ACD). The experimental facility consists of two similar adjacent rooms connected by a door over which the ACD device was installed. The tracer gas technique was used to calculate the sealing effect achieved with the air curtain at different jet velocities. Using a commercial CFD software, a numerical study was also performed to simulate the heat and mass transfer phenomena, as well as the aerodynamic sealing efficiency. A good agreement was observed between experimental and numerical results, showing that the optimum discharge velocity of the ACD air jet increases almost linearly with the door height, as well as with the temperature difference between both sides of the air curtain. It was possible to establish an empirical correlation that predicts reasonably well the optimum discharge jet velocity of a vertical air curtain device, depending on the temperature difference and the doorway height. An electronic device can be included in the ACD enabling the automatic adjustment of the air curtain jet velocity based this correlation, in order to continuously operate close to maximum sealing efficiency.
- A Study on the Sealing Efficiency of Air Curtains: 2D and 3D ApproachesPublication . Goncalves, J. C.; Costa, J.; Figueiredo, R.; Lopes, A.In industrial refrigerated spaces, such as retail stores, where sometimes doors must be open for long periods, the infiltration loads can represent more than half of the total refrigeration load. The use of air curtains can significantly reduce the air infiltration through doorways and, at the same time, it allows the free access by persons and equipment [1]. Besides the experimental research, computational fluid dynamics (CFD) has been commonly used, either adopting a two dimensional (2D) approach [1] or, more recently, through a three-dimensional (3D) perspective [2,3]. This work presents a numerical and experimental study on the performance of air curtain devices in the aerodynamic sealing of access doors of refrigerated spaces. For this propose, a 3D numerical model was developed aiming at the simulation of the turbulent non-isothermal airflow generated by the air curtain since the moment the door is opened. The calculation domain represents a laboratory scale model consisting of two similar adjacent rooms connected by a doorway over which the air curtain device is installed. One of these rooms represents a refrigerated chamber and the other, the outdoor environment. The numerical study was carried out using a commercial CFD code (ANSYS-CFX) and the turbulence effects were approached by k-_SST turbulent model. In the experimental study, the tracer gas technique was used to estimate the air exchange rate through the doorway in the initial period of the transient process and consequently assess the sealing effect obtained with the air curtain device operating at different jet velocities. The numerical results show that the air curtain simulated is appropriate to protect the doorway in its whole width, and a good agreement is verified with the experimental measurements. Results of a simplified 2D approach are also shown and compared with the 3D simulation