Minimizing the respiratory pathogen transmission: Numerical study and multi-objective optimization of ventilation systems in a classroom

Ventilation strategies to reduce airborne transmission of viruses in classrooms: A systematic review of scientific literature

“…The authors of [ 98 ] compare five ventilation system varying the number and the positions of inlet and outlet vents in the same school classroom (making a ventilation pattern similar to SV, one similar to DCV, one similar to DV, and two UFAD). The CFD simulations of the various distribution systems were launched with the same air speed (0.4 m/s) and the same temperature (about 23 °C) in a classroom of 30 students.…”

“…In brief, the reviewed articles agree that the most advantageous strategies are those that generate an air displacement by setting the inlet and outlet diffusers in opposed places, such as SV [ 86 , 87 ], DCV with ceiling supply diffusers and floor returns [ 84 ], UFAD [ 85 , 98 ] or CJV [ 99 ], reducing the age of air inside a classroom and limiting the horizontal spread of aerosols among students. Attention should be paid to the air speed though so that it does not disrupt the occupants’ comfort [ 85 ].…”

Airborne and aerosol pathogen transmission modeling of respiratory events in buildings: An overview of computational fluid dynamics

“…In this regard, a brief overview of CFD technical details employed in previous studies with important insights is presented in Table 1 . These studies are summarized in different groups of HVAC-design ( Yu et al, 2017 , Anghel et al, 2020 , Jacob et al, 2019 , Mead-Hunter et al, 2013 , Arjmandi et al, 2021 , Sahu et al, 2019 , Leung et al, 2005 , Zhu et al, 2012 , He et al, 2011 , Zhang et al, 2019 , Gao and Niu, 2007 , Kang et al, 2015 , Feng et al, 2012 ), HVAC-disinfection ( Atci et al, 2020 , Noakes et al, 2006 , Feng et al, 2021 ), natural ventilation ( Gao et al, 2009 , Motamedi et al, 2021 ), partitioning ( Cheong and Lee, 2018 ) and PPE ( Kumar et al, 2020 , Pendar and Páscoa, 2020 ). In the HVACdesign as the most common theme, the impact of various HVAC strategies such as mixing ventilation (MV), displacement ventilation (DV), and under-floor air distribution (UFAD) on particle dispersion has been widely studied ( Feng et al, 2012 , Liu et al, 2018 , Jacob et al, 2019 , Correia et al, 2020 , Curseu et al, 2009 , Beggs et al, 2008 , Anghel et al, 2020 , Memarzadeh and Xu, 2012 , Gao and Niu, 2007 , Kang et al, 2015 , Feng et al, 2012 ).…”

“… ( Zhang et al, 2019 ) HVAC- design Distribution of droplet aerosols evaluation in an air-conditioned room with Lagrangian method LES The initial droplet size:1, 10, 20, 50 and 100 μm - Density – 998.2 kg/m 3 , Wall: Different heat-flux at height of human bodies - Adiabatic condition at other walls Inlet-mouth: Exhaled infected airflow: 100 s −1 - Temperature: 35 °C - RH: 90% Inlet: Reflect type and Velocity inlet Outflow: Escape type Comparison of droplet distribution with experimental data The full-scale room with 8.74 (L) m × 4.95 m (W) × 3.63 m (H), containing 16 diffusers and a woman – 2.6 million unstructured cells Yes The influence of supply air temperature and relative humidity on the number of the suspected droplets is less than ventilation rate and air distribution patterns in DV system. ( Arjmandi et al, 2021 ) HVAC- design Transmission of respiratory droplets and optimization of ventilation systems to control the spread of airborne particles in a classroom with Lagrangian method Realizable k-ε Droplet size: 1.25 μm Wall: Constant heat-flux at body surfaces Inlet-mouth: Initial velocity of 0.2m/s - Temperature: 34 °C - Total flow rate: 1.25 e −5 kg/s Inlet: Velocity inlet Comparison of infection concentration at various positions with experimental data of other studies A classroom with 9.77 (L) m × 7.25 m (W) × 3 m (H) occupied by 30 students with a seating arrangement of 5 lines and 6 rows – 23.6 million unstructured cells Yes The case, including the inlets and outlets, separately, on the floor and ceiling of each student, has the better performance to minimize the infection spreading since the maximum value of residential time of infections is 4s in the case study. ( Mead-Hunter et al, 2013 ) HVAC-design CFD simulation based on the Lagrangian discrete particle tracking to simulate the behavior of fibrous filters used to treat aerosols Coupling of the customized particle solver with the volume-of-fluid (VOF) solver as the new solver Particle diameters of 50–1,000 nm – Particle velocity of 0.1m/s.…”

Computational Study of Thermal Comfort and Reduction of CO2 Levels inside a Classroom

“…Until now, there are very few CFD studies in schools where thermal comfort is analyzed considering a large number of students; in [ 26 , 27 ], classrooms without air conditioning and with open windows were studied. On the other hand, other CFD studies inside spaces have considered the transport of particles to study the transmission of contagious diseases in schools [ 28 , 29 ] and hospitals [ 30 , 31 , 32 , 33 ].…”