Effects of Return Air Inlets’ Location on the Control of Fine Particle Transportation in a Simulated Hospital Ward

Abstract

The COVID-19 pandemic has made significant impacts on public health, including human exposure to airborne pathogens. In healthcare facilities, the locations of return air vents in ventilation systems may have important effects on lowering airborne SARS-CoV-2 transmission. This study conducted experiments to examine the influence of different return air vents’ heights (0.7 m, 1.2 m, and 1.6 m) on the particle removal effects in a simulated patient ward. Three different ventilation systems were examined: top celling air supply-side wall return (TAS), underfloor air supply-side wall return (UFAS) and side wall air supply-side wall return (SAS). CFD simulation was applied to further study the effects of return air inlets’ heights (0.3 m, 0.7 m, 1.2 m, 1.6 m, and 2.0 m) and air exchange rates. The technique for order of preference by similarity to ideal solution (TOPSIS) analysis was used to calculate the comprehensive scores of 60 scenarios using a multi-criterion method to obtain the optimal return air inlets’ heights. Results showed that for each additional 0.5 m distance in most working conditions, the inhalation fraction index of medical staff could be reduced by about 5–20%. However, under certain working conditions, even though the distances between the patients and medical personnel were different, the optimal heights of return air vents were constant. For TAS and UFAS, the optimal return air inlets’ height was 1.2 m, while for SAS, the best working condition was 1.6 m air supply and 0.7 m air return. At the optimum return air heights, the particle decay rate per hour of SAS was 75% higher than that of TAS, and the rate of particle decay per hour of SAS was 21% higher than that of UFAS. The location of return air inlets could further affect the operating cost-effectiveness of ventilation systems: the highest operating cost-effectiveness was 8 times higher than the lowest one.

Predicting aerosol transmission in airplanes: Benefits of a joint approach using experiments and simulation

“…To make faster predictions, various numerical simulation models have also been proposed. A lot of work has been done both from the perspective of general modeling of aerosol spread, [6][7][8][9][10] and for making predictions in specific scenarios, ranging from hospital rooms, [11][12][13] classrooms 14 and restaurants, 15,16 to aircrafts, 17 cars 18 and buses. 19,20 We refer to References 21-23 for comprehensive reviews of different computational models for aerosol transmission.…”

Numerical Simulation of Heat Transfer and Spread of Virus Particles in the Car Interior

“…The CFD approach to the study of the spread of viral particles was used to simulate the transmission of the virus in urban public places [46,47], considering different landscape designs and air speeds, in rooms with different partitions [48][49][50][51][52], risks assessment [53][54][55], and construction drainage pipes [56]. Options for optimizing ventilation and air The factors that provide a comfortable microclimate and the theoretical foundations for modeling the microclimate in cabins based on the balance equations of heat flows are presented in [1][2][3][4][5], "the processes of convective heat exchange with the environment are described" [6][7][8][9][10].…”

“…The CFD approach to the study of the spread of viral particles was used to simulate the transmission of the virus in urban public places [46,47], considering different landscape designs and air speeds, in rooms with different partitions [48][49][50][51][52], risks assessment [53][54][55], and construction drainage pipes [56]. Options for optimizing ventilation and air conditioning systems are considered, including the spread of a part of the virus in buildings [57], buses and trains [58,59], and in two-phase flow systems [60][61][62][63].…”

The airflow distribution and aerosol diffusion rules in the negative pressure isolation ward

“…The effects of air supply temperature, relative humidity, ventilation rate and ventilation pattern on the number of aerosols suspended, deposited, and escaped droplets Villafruela et al 18 The suitability of adopting a displacement ventilation strategy in airborne infection isolation rooms Liu et al 19 In a typical two-bed ward layout, which locations have the most significant biological aerosol deposition Ren et al 20 Determine the optimal return air height under different ventilation types discovered that compared with mixing ventilation, the adoption of displacement ventilation strategy can reduce the exposure to contaminants of health worker. Recently, Kong et al 16 considered that the side return air can effectively reduce exposure of pollutants and improve the filtration efficiency.…”

“…Liu et al 19 compared the cross-infection situation in a two-bed hospital ward, and the results showed that unilateral downward ventilation had better removal effect on bioaerosols than bilateral downward ventilation. Using experiments and multi-criterion analysis (i.e., the filtration effect and energy consumption), Ren et al 20 found that the optimal height of the return air vent was constant under different air supply types.…”