Particle transport in low-energy ventilation systems. Part 2: Transients and experiments.
Providing adequate indoor air quality while reducing energy consumption is a must for efficient ventilation system design. In this work, we study the transport of particulate contaminants in a displacement-ventilated space, using the idealized 'emptying filling box' model (P.F. Linden, G.F. Lane-serff and D.A. Smeed (1990) Emptying filling boxes: the fluid mechanics of natural ventilation, J. fluid Mech., 212, 309-335.). In this paper, we focused on transient contaminant transport by modeling three transient contamination scenarios, namely the so called 'step-up', 'step-down', and point source cases. Using analytical integral models and numerical models we studied the transient behavior of each of these three cases. We found that, on average, traditional and low-energy systems can be similar in overall pollutant removal efficiency, although quite different vertical gradients can exist. This plays an important role in estimating occupant exposure to contaminant. A series of laboratory experiments were conducted to validate the developed models.


CONCLUSIONS
The results presented here illustrate that the source location plays a very important role in the distribution of contaminant concentration for spaces ventilated by low energy displacement-ventilation systems. With these results and the knowledge of typical contaminant sources for a given type of space practitioners can design or select more effective systems for the purpose at hand.
Bolster
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DT
Department of Mechanical and Aerospace Engineering, University of California-San Diego, La Jolla, CA, USA. diogobolster@gmail.com
Linden
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PF
D000392:Air Movements; D016902:Air Pollution, Indoor / Q000032:analysis* / Q000517:prevention & control; D004780:Environment, Controlled; D004781:Environmental Exposure / Q000032:analysis*; D004867:Equipment Design; D005374:Filtration / Q000379:methods; D006801:Humans; D008962:Models, Theoretical; D052638:Particulate Matter / Q000032:analysis*; D014691:Ventilation / Q000379:methods*
D052638:Particulate Matter