Loading...
2 results
Search Results
Now showing 1 - 2 of 2
- Analysis of the air infiltration through the doorway of a refrigerated room using different approachesPublication . Gonçalves, J. C.; Costa, J.J.; Lopes, A.M.G.This paper presents the study of the air movement through the doorway of a refrigerated room, using both numerical and experimental approaches. Firstly, a comparison is made between the experimentally observed infiltration rates and the predictions by seven empirical models. For different test conditions of the specific laboratory configuration under analysis (a refrigerated room at laboratory scale), the infiltration rate was measured using the tracer gas technique. A three-dimensional numerical model was developed to simulate the heat and mass transfer phenomena, using a commercial CFD code (ANSYS-CFX®). For the simulations, turbulence effects were taken into account using the k- SST turbulence model. CFD results showed a good agreement with experimental data, confirming that the numerical model is appropriate to evaluate this physical phenomenon. The experimental and numerical results showed that the neutral flow level is located above the doorway mid-height and that the maximum airflow velocity occurs near the doorposts. Results also evidenced that, although most of the empirical models tend to overestimate the infiltration rate, some of them present a quite good prediction ability. Measurements in a real scale refrigerated room confirmed the trend obtained in the laboratory installation.
- CFD modelling of aerodynamic sealing by vertical and horizontal air curtainsPublication . Goncalves, J.C.; Costa, J.J.; Figueiredo, A.R.; Lopes, A.M.G.This work presents a comparative study of the aerodynamic sealing of doorways of refrigerated rooms, obtained by vertical and horizontal air curtain devices (ACD). The sealing efficiency is estimated for different situations, with the ACD installed inside, outside or on both sides of the door. For this purpose, a numerical model was developed for the simulation of the turbulent non-isothermal 3D airflow generated by the air curtain in the transient period after the door is opened. The buoyancyinduced airflow field when the ACD is turned off and the door is open was taken as a reference to assess the sealing efficiency. Numerical results are plausible and comply with the physical interpretation of the convective phenomena. In line with previous investigations, the optimum velocity of the air jet was found, corresponding to the highest sealing effect. The advantage of installing the ACD outside the refrigerated room was shown by the present simulations. According to the present study, downward blowing air curtains present better sealing efficiency (over 70%) compared to horizontal jet air curtains (about 55%). Although the direct air recirculation provides a better sealing efficiency (over 80%), the system complexity and the installation and maintenance costs inhibit its common use.