Aerosol Spatial Distribution in Ventilated Rooms

One of the challenges in the areas of air quality and environmental studies is to measure the spatial distribution of aerosols so that exposure can be better assessed and appropriate control strategies can be implemented. There is a lack of data on dust spatial distribution in mechanically ventilated airspaces because of lack of adequate sampling techniques.  The existing aerosol sampling technology is a single point measurement, i.e., one measurement at one point at a time. To study the aerosol spatial distribution and behavior, it is critical to measure aerosol concentrations across an airspace at multiple points during the same time period.  Otherwise, the time required for each measurement point (typically on the order of hours or days for mass concentration) will introduce large errors in aerosol distribution patterns which are highly time dependent.   In this project, a multi-point sampler (Figure 1) was developed and used to measure the dust spatial distribution at different ventilation systems in a mechanically ventilated airspace.

The objectives of this proposed research are to develop the technology for multi-point air sampling using critical air flow devices to measure aerosol spatial distribution at multiple points during the same time period in ventilated airspaces. The advantages includes:

	Multi-point measurement at the same time
	Constant flow rate independent of pressure
	Accurate, reliable and inexpensive

Experimental results show that the dust mass concentration varies widely within the mechanically ventilated airspace.  Ventilation rate, ventilation system, occupant activities, dust source, air cleaning and infiltration all affect the dust spatial distribution. Figure 2 shows that the dust spatial distribution within the mechanically ventilated swine building. 

Figure 2 dust spatial distribution within the mechanically ventilated swine building

Expected results from this proposed study include a technology to measure spatial distribution of aerosol concentration.  The instrumentation and the measurement technique will be useful for scientific communities and industries related to air quality control.  The study will yield a data base for validation of models (for this study as well as other researchers) and an analytical method (a computer model) to evaluate alternative aerosol control strategies such as source control, ventilation effectiveness and air distribution systems. 

Related Papers

Development of a Multi-Point Aerosol Sampler Using Critical Flow Control Devices

Development of a Critical Air Flow Venturi for Air Sampling

Dust Spatial Distribution in a Typical Swine Building

Facilities Used on this Project

Air Quality Laboratory

Room Ventilation Simulator

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