Numerical investigation of radon dispersion and dose assessment for typical ventilation schemes with an air purifier

Poor indoor air quality in residential buildings always threatens human health, such as sick building syndrome (SBS), respiratory diseases and low sleep quality. Although fresh air can dilute the concentration of air pollution, the widely used natural ventilation is uncontrolled and its ventilation rate is usually insufficient. Even in the indoor environments of residential buildings where the mechanical ventilation system is installed, different forms of ventilation systems have their unique problems. To create a healthy indoor environment, this investigation proposed a novel push-relay-pull mechanical ventilation system (fresh air supplying system) achieved by combining the mechanical air supply system (push), intermediate relay system (relay) and mechanical exhaust system (pull). This investigation further quantitatively evaluated the performance of the proposed system by comparing it with the traditional mechanical fresh air ventilation system using the age of air, infection risk and carbon dioxide (CO2) concentration indexes. The proposed system only needs to install one set of ducts as the traditional mechanical ventilation systems. It can ensure that all rooms would maintain good air quality, and also prevent the spread of pollutants, reduce the average infection risk of people inside a residential building and are conducive to epidemic prevention and control.

Section: Discussionmentioning

confidence: 99%

Ventilation performance of multi-room in residential building with the proposed novel mechanical ventilation system: A case study

Zhao

Yin

Liu

et al. 2023

“…Grey relational analysis has a wide range of applications in many domains, such as industry, agriculture, economics and energy. 41 In this study, grey relational analysis was used to obtain the importance of each parameter in reducing the risk of infection and particle count concentration. Grey relational analysis proceeds as follows:…”

Section: Grey Relational Analysismentioning

confidence: 99%

Mitigation of airborne transmission of COVID virus between occupants in a confined room with an air purifier

Wang

et al. 2023

Self Cite

This study evaluated the effect of ventilation rate and air supply angle of an air purifier using computational fluid dynamics to determine the dispersion of airborne COVID virus exhaled by an infected person. The risk of infection for an occupant was determined based on the virus concentration in the active area and accumulated particle dose within the breathing zone by varying the ventilation parameters. The air purifier was found to provide a local dilution and would block the development of an expiratory jet for a short time to reduce transmission risk. Compared to the case without an air purifier, the maximum reductions were 94.27% in the accumulated dose and 53.2% in the particle count concentration. In the breathing area, the larger air supply angle (90° > 60° > 30°) is better when the ventilation rate was 27.0 m3/h and 40.5 m3/h. Otherwise, 60° air supply angle is preferable where the ventilation rate was 54.0 m3/h. Assessing the results with the grey relational analysis revealed that the relational degree for particle count concentration was greater by varying the ventilation rate than by varying the air supply angle. However, the relational degree according to the accumulated dose was greater by varying the air supply angle than by increasing the ventilation rate. These findings may provide an important control strategy to effectively mitigate the risk of infection in a confined room by using an air purifier.

“…1,6,12,[19][20][21][22] Measurement and numerical studies have examined the impact of air purifiers, upon various pollutants within apartments. 23,24 Seasonal variations have been identified and may be associated with occupant ventilation behaviour, outdoor conditions, ventilation rates 1,25 or varying emission rates from building products. [26][27][28] Continuous, time-based, measurements tend to have been used in smaller studies but can provide further insight into these dynamic relationships and behaviours.…”

Section: Introductionmentioning

confidence: 99%

“…1,6,12,19–22 Measurement and numerical studies have examined the impact of air purifiers, upon various pollutants within apartments. 23,24 Seasonal variations have been identified and may be associated with occupant ventilation behaviour, outdoor conditions, ventilation rates 1,25 or varying emission rates from building products. 26–28…”

Section: Introductionmentioning

confidence: 99%

Seasonal variations and the influence of ventilation rates on IAQ: A case study of five low-energy London apartments

Stamp

Burman

Shrubsole

et al. 2021

The indoor air quality (IAQ) of five low-energy London apartments has been assessed through the measurement of 16 key pollutants, using continuous and diffusive methods across heating and non-heating seasons. This case study approach aimed to assess the presence of pollutants within low-energy apartments and to better understand the role of ventilation and seasonal variations in indoor air quality. The results indicate strong seasonal variations, driven by increased natural ventilation rates over the summer monitoring period. A combined metric for indoor and outdoor pollutants ( Itot) suggests that the IAQ in the winter ( Itot = 17.7) is more than twice as bad as that seen in the summer ( Itot = 8.6). Formaldehyde concentrations were lower in the non-heating season, indicating increased ventilation rates more than offset increased off-gassing, in contrast to findings in other studies. However, increased summertime ventilation rates were observed to increase the proportion of outdoor pollutants entering the internal environment. This resulted in higher indoor concentrations of NO2 in the summer than the winter, despite significant reductions in outdoor concentrations. These results demonstrate the impact of ventilation practices upon IAQ, the influence of occupant actions and the complex relationship ventilation rates play in balancing indoor and outdoor sources of air pollution.