Performance evaluation of a novel personalized ventilation-personalized exhaust system for airborne infection control

Abstract

In the context of airborne infection control, it is critical that the ventilation system is able to extract the contaminated exhaled air within the shortest possible time. To minimize the spread of contaminated air exhaled by occupants efficiently, a novel personalized ventilation (PV)-personalized exhaust (PE) system has been developed, which aims to exhaust the exhaled air as much as possible from around the infected person (IP). The PV-PE system was studied experimentally for a particular healthcare setting based on a typical consultation room geometry and four different medical consultation positions of an IP and a healthy person (HP). Experiments using two types of tracer gases were conducted to evaluate two types of PE: Top-PE and Shoulder-PE under two different background ventilation systems: Mixing Ventilation and Displacement Ventilation. Personalized exposure effectiveness, intake fraction (iF) and exposure reduction (ε) were used as indices to evaluate the PV-PE system. The results show that the combined PV-PE system for the HP achieves the lowest intake fraction; and the use of PE system for the IP alone shows much better performance than using PV system for the HP alone.

Airborne spread of expiratory droplet nuclei between the occupants of indoor environments: A review

“…Percentage reduction (compared to the case with no personalized ventilation [ PV ]) in the intake of the expiratory flow from the infected individual (yellow) by the exposed individual (blue) when using PV (A) and using PV and/or personalized exhaust (B), where RMP denotes a round movable panel mounted on a movable arm‐duct attached to a desktop…”

“…The use of PE for an infected individual shows much better performance when compared to the use of PV for a healthy individual only (Figure B). It is important to realize that the use of PV helps a little when PE is already used, although the combination of PV‐PE can achieve the lowest cross‐infection risk . Such a PV‐PE combination is also effective in capturing the expiratory flow and thus reducing the risk of cross‐infection in aircraft cabins .…”

“…Using MV, face‐to‐face orientation causes the highest risk of cross‐infection and face‐to‐back the lowest risk . Using DV, one sitting and one standing occupant causes the highest risk, as the upward flow generated by DV increases the transmission of expiratory flows from a sitting individual to a standing individual …”

“…Influence of relative orientation and posture on cross‐infection risk, where the cross‐infection risk decreases from (A) to (E) when using mixing ventilation and from (F) to (H) when using displacement ventilation; note that the left‐hand manikin represents the infected individual and the right‐hand one the exposed individual…”

“…The most widely investigated breathing mode in previous studies, for both the infected and exposed individual, was “exhalation through mouth and inhalation through nose.” A number of studies were carried out using the “non‐breathing” mode for the exposed manikin . Most CFD studies simulated an “inhalation only” mode for the exposed manikin and an “exhalation only” mode for the infected manikin .…”