The effect of the thermal plume generated by body heat dissipation on the containment of fume hood

Abstract

The impact of human body heat dissipation on the containment of a fume hood was conducted via experiments and numerical model. The experiments evaluated hood face velocity and the temperature around the mannequin; the results validated the simulation. The numerical model was based on the governing equations of fluid flow via the finite volume method. The face velocities (0.3–0.9 m·s− 1 ) and temperature differences (11°C, 8°C and 5°C) between the surface of the mannequin and its surroundings were used as variables. The numerical results show that in addition to the blockage effect of the worker standing in front of the fume hood, there is a more important thermal effect on the containment of fume hood. The thermal plume carries pollutants leaking out of the hood face to the breathing zone. The face velocity and dimensionless value (Gr/Re 2 ) are recommended to be 0.4–0.6 m·s− 1 and 20–35 respectively, to reduce the influence of human thermal plume on the containment of fume hood and energy waste. The formula related to the rising distance of thermal plume, Grashof and Reynolds numbers (Gr/Re 2 ) was determined.

Pollutant capture efficiencies in and around the opening surface of a fume hood under realistic conditions

“…They reported that changes in the flow field due to changes in the shape of the worker might affect the concentration in the breathing zone. Liu et al 7 also reported CFD analysis to evaluate the containment performance of the fume hood by simulating an upright worker in front of the fume hood, with the human body surface temperature was set at 31°C and the opening surface air velocity was varied from 0.3 to 0.9 m/s. As a result, they found that the performance of the opening surface was affected by the thermal plume caused by the human heat generation when the opening surface air velocity was less than 0.4 m/s.…”

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

“…29 Furthermore, the realizable k-ε model has been proven to predict the airflow inside of the hood chamber precisely. 3,18 Obtaining a better agreement would necessitate the use of LES, which however is much more computationally expensive than steady RANS. 29 Therefore, the realizable k-ε model with SIMPLE algorithm was adopted for numerical calculations.…”

“…Airborne contaminants can linger for long periods of time in the circular eddy current behind the sash and near the doorsill, which can heighten the risk of contaminant leakage. 18 Pressure loss also fell by 30.5% by reducing the recirculation zones inside the hood, thereby limiting the energy consumption of the hood. 19 A planar jet was developed to form a layer of clean air that can reduce the amount of pollutants escaping from the eddy near the doorsill.…”