EFFECT OF CONTAMINANT PROPERTIES AND TEMPERATURE-GRADIENTS ON THE EFFICIENCY OF TRANSIENT GASEOUS CONTAMINANT REMOVAL FROM AN ENCLOSURE - ANUMERICAL STUDY

This paper reports the results of a numerical study on the transient r emoval of a contaminant from a two-dimensional enclosure with one inle t and one outlet. The influence of buoyancy forces due to thermal and concentration gradients, contaminant diffusivity, inlet velocity and o utlet disposition over the cleaning-time are studied. The governing eq uations of the laminar flow (continuity, momentum, energy and contamin ant concentration) are solved by means of the SIMPLEC algorithm. Sever al simulations of the same test case have been made, using two numeric al schemes: PLDS and SMART, in order to determinate which one provides better performances. For isothermal situations, the time required to remove the contaminant is studied parametrically as a function of the outlet position and the governing dimensionless numbers (Reynolds numb er, Schmidt number and solutal Rayleigh number), while the effect of h orizontal temperature differences is studied in several situations in which it plays an important role. Buoyancy forces are found to have a strong influence over the flows and, in consequence, over the cleaning times. (C) 1998 Published by Elsevier Science Ltd. All rights reserve d.