Full-size experimental assessment of the aerodynamic sealing of air curtains for particulate matter

Abstract

An air curtain is used to ensure an adequate separation between two compartments that is aimed to restrict, a clean one and a contaminated one. The air curtain performance is improved with the use of an air extraction from the “contaminated” compartment. The aerodynamic sealing of an optimized air curtain is assessed regarding particulate matter. The evaluation using visual assessment of the aerodynamic sealing using a cold smoke source is validated against PM 10 detection. It is shown that the air curtain presents a good aerodynamic sealing for the particulate of PM10 and PM2.5 classes and that the visual assessment method can lead to similar results. An equation was obtained with a view to be used to predict the level of aerodynamic sealing of the air curtain when the exhaust rate becomes too low. Another equation was obtained for predicting the average velocity through the door protected by the air curtain required to obtain an aerodynamic sealing, as a function of the jet parameters (nozzle average velocity and thickness). These test results prove that the air curtain, complemented with an air exhaust from the “contaminated compartment”, is suitable to provide an acceptable aerodynamic sealing for the particulate matter. Practical application: The findings of this research are applicable when it is necessary to retain the contamination due to particulate matter using a soft boundary, as air plane jets. This is applicable to medical care centres to reduce the possibility of contamination due to bacteria between different compartments or in pharmaceutical process units to avoid cross contamination among them.

Full-Size Experimental Assessment of the Aerodynamic Sealing of Low Velocity Air Curtains

“…This paper describes the research carried out in phase (iiib), exploring the possibility of using a low nozzle velocity to optimize the use of plane jets for separating two different spaces. It presents a much larger set of results compared to the previous paper [27]. This paper also reviews the previous results obtained by the authors (under both isothermal and high temperature conditions [3,[26][27][28][29]) and updates the equations to predict the air curtain sealing performance applicable for both isothermal flow and for when the air curtain is disturbed by heat sources.…”

“…Considering that the jet entrainment air increases with the volume flow rate at the air curtain nozzle, it is beneficial to use jet velocities that are as low as possible. A more detailed description of these aspects can be found in [27].…”

“…Considering that the jet entrainment air increases with the volume flow rate at the air curtain nozzle, it is beneficial to use jet velocities that are as low as possible. A more detailed description of these aspects can be found in [27]. For an undisturbed environment (e.g., isothermal flow), it is possible to achieve the aerodynamic sealing through the imposition of a very small uniform horizontal air stream through the opening.…”

“…To obtain the exhaust flow rate that provides aerodynamic sealing under different air curtain characteristics, a research program was established, consisting of the following phases: (i) small-scale experiments using water as the work fluid [26]; (ii) Computational Fluid Dynamics (CFD) simulations to verify if the small-scale test results were applicable to a full-size air curtains [28]; (iii) full-size air curtain experiments. The full-size experiments were subdivided into two sets of tests, namely: (iiia) assessment of the aerodynamic sealing for PM10 and comparison with the visual assessment [27] and (iiib) optimisation of the aerodynamic sealing for low Reynolds number jet velocities. The typical dimension For an undisturbed environment (e.g., isothermal flow), it is possible to achieve the aerodynamic sealing through the imposition of a very small uniform horizontal air stream through the opening.…”

“…The typical dimension of bacteria ranged from 0.5 µm to 5 µm and, for the purpose of the assessment of the aerodynamic sealing, can be associated with the corresponding particle sizes. Therefore, in a previous study [27], the aerodynamic sealing of the curtain for bacteria was analysed for the aerodynamic sealing of PM10 particulate. In the phase (iiia) assessment using PM10, detection was compared with the visual assessment of the aerodynamic sealing using a cold smoke source to validate the visual assessment method, and it was proved that such a method can be used to assess plane jet aerodynamic sealing.…”