Optimising multi-vent module-based adaptive ventilation using a novel parameter for improved indoor air quality and health protection

As infectious respiratory diseases are highly transmissible through the air,researchers have improved traditional total volume air distribution systems to reduce infection risk.Multi-vent module-based adaptive ventilation(MAV)is a novel ventilation type that facilitates the switching of inlets and outlets to suit different indoor scenarios without changing ductwork layout.However,little research has evaluated MAV module sizing and air velocity selection,both related to MAV system efficiency in removing contaminants and the corresponding level of protection for occupants in the ventilated room.Therefore,the module-source offset ratio(MSOR)is proposed,based on the MAV module size and its distance from an infected occupant,to inform selection of optimal MAV module parameters.Computational fluid dynamics simulations illustrated contaminant distribution in a two-person MAV equipped office.Discrete phase particles modelled respiratory contaminants from the infected occupant,and contaminant concentration distributions were compared under four MAV air distribution layouts,three air velocities,and three module sizes considered using the MsOR.Results indicate that lower air velocities favour rising contaminant levels,provided the ventilation rate is met.Optimal contaminant discharge can be achieved when the line of outlets is located directly above the infected occupant.Using this parameter to guide MAV system design,85.7% of contaminants may be rendered harmless to the human body within 120 s using the default air vent layout.A more appropriate supply air velocity and air vent layout increases this value to 91.4%.These results are expected to inform the deployment of MAV systems to reduce airborne infection risk.

Effective improvement of a local thermal environment using multi-vent module-based adaptive ventilation

Indoor thermal comfort is essential as it improves living standards.Activity scenarios of personnel are in the process of a dynamic change.In most interior spaces with fixed working stations,people directly blown by cold air have a poor thermal experience.Therefore,to meet the differentiated environmental demands,one challenge is to explore novel ventilation strategies to satisfy the changing environmental needs.An adaptive strategy,multi-vent module-based adaptive ventilation(MAV),was designed to increase the adjustability of air distribution and better adapt to variable demands.A classroom was chosen as a representative model with multiple scenarios during its use.Simulations were conducted to verify the three-level control effect of MAV on improving the thermal environment.The results revealed that different vent solutions create different airflow patterns and thermal environments,which can be matched to the scenarios.The scale for ventilation efficiency No.4,which measured the influence scope of supply air,was used to evaluate the zoning division control in MAV.The space under the charge of a concerned MAV module showed a higher SVE4 than that at other zones.This implied that the zoning division can be effectively implemented.Thermal comfort measured using the air diffusion performance index,predicted mean vote,and draught rate showed that the application of MAV is better than that of the fixed MV mode,and the discomfort experienced when exposed to cold air can be avoided.It is believed that these results will help extend the research of adaptive ventilation strategies.