Numerical study and experimental optimization of air curtains
he main objective of the present thesis is to study and optimize the sealing efficiency of air curtains. Therefore, the phenomenology of the breakthrough and the parameters which affect it has been studied. However, considering the level of turbulence in the studied flowfields, this work employs num...
| Autor: | |
|---|---|
| Formato: | tesis doctoral |
| Estado: | Versión publicada |
| Fecha de publicación: | 2015 |
| País: | España |
| Recursos: | CBUC, CESCA |
| Repositorio: | TDR. Tesis Doctorales en Red |
| OAI Identifier: | oai:www.tdx.cat:10803/299072 |
| Acesso em linha: | http://hdl.handle.net/10803/299072 https://dx.doi.org/10.5821/dissertation-2117-95693 |
| Access Level: | acceso abierto |
| Palavra-chave: | 536 |
| Resumo: | he main objective of the present thesis is to study and optimize the sealing efficiency of air curtains. Therefore, the phenomenology of the breakthrough and the parameters which affect it has been studied. However, considering the level of turbulence in the studied flowfields, this work employs numerical methods which will allow us to take all the transport phenomena into account, for both laminar and turbulent regimes. This is not the first effort within the {\sc cttc} (``Centre Tecnològic de Transferència de Calor'') research group on this subject, but the continuation of a research activity carried out in the past years. For this purpose, chapter 1 contains an introduction to air curtains, and the basic phenomenology is discussed. The different stages of an air jet are detailed. It is also given a discussion on when the installation of these devices should be considered as a good solution for air flow sealing. In this chapter are also defined the basic concepts used throughout this work. It ends with a brief description of the three main approaches employed in this thesis to analyse air curtains: computational fluid dynamics, semianalytical methods and experimental measurements. The semianalytycal methods, which are suitable only for steady regime calculations, are introduced in chapter 2. In this chapter it is also described the interface developed at Centre Tecnològic de Transferència de Calor to evaluate the thermal efficiency and other relevant aspects for different configurations of air curtains. The main results obtained in such geometries are also presented. The semiananlytycal approach allows to characterize the air curtains with a much less time consuming method than higher level calculations. In chapter 3, the Computational Fluid Dynamics methodology is described, with Large Eddy Simulation as approach. The models employed to solve the Navier Stokes equations are Smagorinsky and Wale. A simmetry preserving discretization is employed. The solvers employed are also outlined. Finally, illustrative results obtained with the air curtain under several conditions are presented. In chapter 4 special emphasis has been placed on the experimental measurements of actual air curtains. This interest resulted on a detailed study about the standard on the characterization of air curtains, and the construction of an experimental set up according the standard requirements.The more significant results are presented. In chapter 5 a plenum optimization procedure is carried out. Both experimental and numerical approaches are employed. In chapter 6 the appplication of air curtains to refrigerating chambers is studied in detail. The results obtained from CFD simulation, semianalytical calculations and experimental measurements have been compared. According to the results obtained and presented the objective of optimizing air curtains proposed in this thesis have been satisfied. |
|---|