Treballs Finals de Màster d'Enginyeria Química, Facultat de Química, Universitat de Barcelona, Curs: 2015-2016, Tutors: Alexandra Bonet Ruiz, Joan Llorens LlacunaThe use of industrial chimney rise up overall in 20th century, during industrial revolution. Until now, the estimation of values of pollutants emitted by industry were made through atmospheric dispersion equations. These models are very effective, because it is not necessary a lot of information to obtain a pretty good estimation. Nowadays, due to technological advances, the computer became a powerful calculus engine. Because of that, it has been possible to develop programs to perform more accurate simulations, like Computer Fluid Dynamic (CFD) software. CFD is predicting what will happen, quantitatively, when fluids flow is affected by different variables, like heat, chemical reaction, mechanical movement, mass transfer… This project is focused on the study of the immission in a multiple stack system. The CFD selected to perform this work is Ansys. Through this, different variables, such as airstream and height of chimney will be changed to study the effect on maximum immission