Indices for ventilation efficiency and their numerical computation

Abstract

The paper addresses methods to evaluate the ventilation efficiency both in regard to air exchange and to contaminant removal in a room. Extra variables are introduced via transport differential equations which are solved by Computational Fluid Dynamics (CFD). Ventilation efficiency indices are defined and computed by alternative methods with an excellent agreement. For the numerical calculations a test chamber with a fume cupboard has been modelled and simulated. The paper discusses peculiarities in the calculation of the passive scalar equations to ensure mass conservation. Guidelines for optimal locations of the exhaust grilles of ventilation systems have been proposed to maximize ventilation efficiency.