Otimização de um mesclador de gnv/ar

Proceedings of ENCIT 2012 Copyright © 2012 by ABCM

14 Brazilian Congress of Thermal Sciences and Engineering November 18-22, 2012, Rio de Janeiro, RJ, Brazil

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NUMERICAL ANALYSIS AND OPTIMIZATION OF MIXERS
Jônathas Assunção S. N. de Castro, [e-mail] Taygoara Felamino de Oliveira, [e-mail]
Universidade de Brasília, Campus Universitário Darcy Ribeiro, Brasília – DF, CEP 70910-900

Carlos Humberto Llanos Quintero, [e-mail]
Universidade de Brasília, Campus Universitário Darcy Ribeiro, Brasília – DF, CEP 70910-900

Abstract. The purpose of this paper is to present numerical analysis of the CNG-air mixers and propose its geometric optimization. The mixer is the section where mixing between air and fuel occurs. This section is associated with loss of pressure energy, increasing the emission of pollutants and the loss of power in a combustion engine. This work aims the development of a mixer with lower pressure drop and more homogeneous mixture. The flow inside a conventional mixer is evaluated through a numerical methodology and its comparison with analytical and experimental results. The diffusion rate of the CNG and air molecules increases with the Reynolds number, however, in the prototype tested the quality of the mixture, i.e., its homogeneity independs of the flow Reynolds, being dependent only of the geometry of the mix section. Keywords: OpenFOAM, mixer, orifice plate, turbulence, compressed natural gas (CNG).

1. INTRODUCTION Natural gas was brought to the center of the current debate on the issues of energy, environment and climate. One of his strengths that provided its leading position is the lower emissions of carbon dioxide per energy produced than other fossil fuels. The burning of CNG – compressed natural gas, is cleaner and more efficient, allowing therefore its penetration in various markets, including domestic and commercial heating, industrial processes and electricity. In a recent study of MIT –