The influence of air supply inlet location on the spatial-temporal distribution of bioaerosol in isolation ward under three mixed ventilation modes

The high concentration of viral bioaerosols within the negative pressure isolation wards could pose a challenge to preventing potential cross-infection amongst healthcare workers (HCWs) and patients. Using the Euler–Lagrange methodology, this study numerically simulated the spatial and temporal distribution characteristics of bioaerosols in a typical negative pressure isolation ward as well as determined the interaction of ventilation mode and patient posture on ward ventilation performance. The removal effect of particle groups produced by two respiratory behaviours (breathing and coughing) was quantitatively analyzed, and the effect of exhaust air ratio and air exchange rate on particle distribution was discussed. The results showed that the migration characteristics of bioaerosol particles were sensitive to both the ventilation pattern and patient posture, which showed significant interactions. On this basis, the ventilation pattern with the best ventilation performance was evaluated, showing a particle removal effect of 70–85%. Due to the initial momentum difference, the diffusion behaviour of cough and breath particles was not consistent, but optimizing the airflow distribution near the exhaust outlet could improve their removal efficiency in the meantime. Further studies found that equal exhaust air velocity ratio facilitated the removal of aerosol particles, and an appropriate increase in the air exchange rate could also reduce the particle content.

Section: Introductionmentioning

confidence: 99%

Spatial and temporal distribution of bioaerosols produced by patients with different postures in a negative pressure isolation ward under different ventilation modes

Li,

Ma,

Liao

2024

“…[21][22][23] To reduce the age of the air and improve the pollutant removal efficiency, fresh air can be sent directly into the working area and particulate matter discharged immediately. 24,25 Local ventilation is the first choice for industrial ventilation and pollutant removal, 26,27 because it can directly discharge harmful substances near the pollution source using a small amount of air. The collection efficiency of local exhaust systems is affected mainly by the form of the exhaust hood.…”

Section: Introductionmentioning

confidence: 99%

“…21–23 To reduce the age of the air and improve the pollutant removal efficiency, fresh air can be sent directly into the working area and particulate matter discharged immediately. 24,25…”

Section: Introductionmentioning

confidence: 99%

Numerical investigation on particle removal and energy consumption of supplied and recirculated ventilation for industrial workshop

Lan

Diao

2023

In the weld back-cleaning process, many high-concentration pollutants are produced, which can lead to health problems after prolonged exposure. In this study, a novel recirculating stratified ventilation system is proposed that combines supply and recirculating ventilation. It reduces indoor particulate concentration and exhausts air volume based on the air gouging process in a casting workshop. The influences of the supplied and recirculated air velocities on the particle removal efficiency and energy consumption were investigated and compared with those of a traditional exhaust system. The computational fluid dynamics-discrete phase model coupling method was adopted. First, the feasibility of the model was verified using previously published experimental data. The concentration of the unsteady particles was then simulated with different supplied and recirculated air velocities in the ventilation system. The particles were dispersed owing to the influence of the heat-source temperature. With an increasing supplied air velocity and constant recirculated air velocity, the average particle concentration was decreased. The results show that the particle removal efficiency can be improved by approximately 100%, and 90% of the energy can be saved to achieve the same removal efficiency as a traditional ceiling exhaust system.

“…1,2 Ventilation is regarded as an effective method to control indoor air parameters and dilute and/or remove indoor pollutants. 3 Nevertheless, ventilation methods have a great influence on the ventilation effect. Work efficiency and air quality can be optimized with a low energy cost by using an appropriate ventilation method.…”

Section: Introductionmentioning

confidence: 99%

“…5 Mixing ventilation (MV) was applied to various types of building spaces with a long history of development. 3 Some studies have been carried out to improve the heating performance of MV. 4,6,7 At the same time, some advanced ventilation methods have been proposed.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of heating performances of different ventilation methods in an office

Li,

Essah,

et al. 2023

In this study, 12 cases were investigated in an office-layout room using experiments and computational fluid dynamics (CFD) simulations. The heating performances of four ventilation methods (i.e. mixing ventilation (MV), stratum ventilation (SV), deflection ventilation (DeV) and impinging jet ventilation (IJV)) were comprehensively compared by various evaluation indexes (i.e. predicted mean vote (PMV), draught rate (DR), vertical air temperature difference (△T), air diffusion performance index (ADPI), energy utilization coefficient (EUC), air change efficiency (ACE) and contaminant removal efficiency (CRE)). Better thermal comfort was found in rooms heated by SV and DeV. The PMV, DR and △T under SV and DeV complied with Category B of ISO 7730:2005, and the ADPI was in full compliance with the stipulation of ANSI/ASHRAE 113-2022. For the energy-saving characteristic, the targeted-occupied-zone ventilation methods (i.e. SV, DeV and IJV) can effectively deliver warm air to the occupied zone, with the EUC values higher than unity and thus providing a good potential for energy saving. SV and IJV showed slightly higher ACEs in the breathing zone. The contaminant removal effectiveness of SV, DeV and IJV was comparable. Under the combined influence of occupant thermal plumes and locations of exhausts, MV showed a high CRE. However, the CRE under MV decreased significantly when the exhausts were not above occupants. In the case of supply air parameters in this study, the entropy-weight method indicated that DeV and SV had a better overall performance for winter heating, followed by IJV and then MV.