Investigation on improving fume hood performance via elimination of internal vortices: Experiments and CFD

Abstract

The design elements of a fume hood and the synergy between them are essential for a fume hood to be used for containment in a chemical laboratory. A computational fluid dynamic simulation with an orthogonal design was validated and executed to determine the aerodynamic characteristics of the fume hood. The ventilation efficiency, that is, the ratio of tracer gas concentration in the exhaust outlet to the hood chamber was introduced as an indicator to evaluate fume hood performance. The ventilation efficiency was found to vary between 4.7 and 12.9 with different baffle opening ratios. The designed doorsill could effectively inhibit the separation of the air boundary layer and thus avoids vortex generation behind the doorsill. The auxiliary air supply would eliminate the eddies behind the sash and could further increase the ventilation efficiency to 13.9. All the designed elements above jointly contribute to the absence of vortices in the flow pattern that is within the hood chamber. The airflow would move from top to bottom and from outside to inside, which would minimize the spread of pollutants to the breathing zone. This paper is intended to contribute to the optimization of the aerodynamic design of fume hoods in chemical laboratories.