Numerical Investigation on the Influence of Contaminant Source Location,Occupant Distribution and Air Distribution on Emergency Ventilation Strategy

Abstract

The purpose of emergency ventilation is to remove pollutants effectively that may be suddenly released indoors. With the occurrence of indoor terrorism attacks and the accidental release of toxic chemicals, people have paid more attention of such emergency events in recent years. The traditional idea of a strategy for emergency ventilation is simply to supply sufficient fresh air into rooms. However, the positioning of a contaminant source, the distribution of occupants and the overall airflow pattern are also important factors. A new concept, integrated accessibility of contaminant source (IACS), has recently been proposed to consider those factors simultaneously. By using this concept as a major index of ventilation efficiency, 84 cases with different combinations of contaminant source and ventilation style in a full-scale room in which the occupant distribution is prescribed have been investigated numerically in this paper. The results show that air exchange rate is not the only dominant parameter, and simply increasing it does not ensure a better ventilation effect. It is also shown that when source location varies, the optimal ventilation strategy might need to differ greatly. From these results some rules are proposed to determine best ventilation strategies for different situations.

Keywords

Emergency ventilation Computational fluid dynamics (CFD)Accessibility of contaminant source (ACS)Air distribution

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References

Li JSM , Chow W K : Numerical studies on Performance Evaluation of Tunnel Ventilation Safety Systems : Tunnelling Underground Space Technol 2003;18(5): 435–452 .

Spengler JD , Wilson DG : Air Quality in Aircraft : Proc Institut Mechanic Eng Part E-J Process Mechanic Eng 2003;217(E4): 323–335 .

Awbi HB : Ventilation of Buildings. Abingdon,Spon Press , 2003.

Marshall JW , Vincent JH , Kuehn TH , Brosseau LM : Studies of Ventilation Efficiency in a Protective Isolation Room by the Use of a Scale Mode : Infection Control Hospital Epidemiol 1996;17(1): 5–10 .

Sandberg M , Sjoberg M : The Use of Moments for Assessing Air Quality in Ventilated Rooms : Building Environ 1983;18: 181–197 .

Sandberg M. : Ventilation Efficiency as a Guide to Design : ASHRAE Transaction 1983;89: 455–479 .

Sandberg M : What is Ventilation Efficiency? : Building Environ 1981;16: 123–135 .

Murakami S : New Scales for Ventilation Efficiency and their Application Based on Numerical Simulation of Room Airflow : Proc Intl Symp Room Air Convention Ventilation Effectiveness, University of Tokyo, 22–24 July, 1992, pp. 22–38 .

Kato S , Murakami S , Kobayas H : New Scales for Evaluating Ventilation Efficiency as Affected by Supply and Exhaust Openings Based on Spatial Distribution of Contaminant . 12th Intl Symp Contamination Control, The Japan Air Cleaning Association, 1994, pp. 341–348 .

10.

Zhao B , Li X , Chen X , Huang D : Determining Ventilation Strategy to Defend Indoor Environment Against Contamination by Integrated Accessibility of Contaminant Source (IACS) : Building Environ 2004;39(9): 1031–1038 .

11.

Li X , Zhao B : Accessibility: A New Concept to Evaluate the Ventilation Performance in a Finite Period of Time : Indoor Built Environ 2004;13(4): 287–294 .

12.

Zhao B , Li X , Li D , Yang J : Revised Airexchange Efficiency Considering Occupant Distribution in Ventilated Rooms : J Air Waste Manage Assoc 2003;53(6): 759–763 .

13.

Zhao B , Li X , Yan Q : A Simplified System for Indoor Airflow Simulation : Building Environ 2003;38: 543–552 .

14.

Li X , Yan Q : Field Model of Fires in Subway Tunnels . The 2nd Intl Symp Heating, Ventilation Air Con (Tsinghua, HVAC'95): pp. 392–399 .

15.

Chen Q , Xu W : A Zero-equation Turbulence Model for Indoor Airflow Simulation : Energy Buildings 1998;28: 137–144 .

16.

Patankar SV : Numerical Heat Transfer and Fluid Flow. Washington DC, Hemisphere , 1980.

17.

Zhao B , Zhang Z , Yang X , Li X and Huang D : Numerical Analysis of Microclimate of Desk Displacement Ventilation : J IEST 2004;47(2): online.

18.

Zhao B , Cao L , Li X , Yang X , Huang D : Comparison of Indoor Environment of a Locally Concentrated Clean Room at Dynamic and Steady Status by Numerical Method : J IEST 2004;47: 94–100 .

19.

Zhao B , Li X , Lu J : Numerical Simulation of Air Distribution in Chair Ventilated Room by Simplified Methodology : ASHRAE Trans 2002;108: 1079–1083 .

20.

Zhao B , Li X , Li Y , Yan Q : Indoor and Outdoor Airflow Simulation by a Zero Equation Turbulence Model . Proc 7th Intl Conf Air Distribution in Rooms (ROOMVENT' 2000). Reading University, UK, 9–12 July, 2000: pp. 449–454 .

21.

Zhao B , Li X , Yan Q : Simulation of Indoor Air Flow in Ventilated Room by Zero-equation Turbulence Model : J Tsinghua Univ (Science and Technology) 2001;41(10): 109–113 (in Chinese).

22.

Zhao B , Cao L , Li X : Description of Perforated Panels in Simulation of Airflow Inside Clean Rooms : J Tsinghua Univ (Science and Technology) 2003;43(5): 690–692 (in Chinese).

23.

Yang J , Li X , Zhao B : Prediction of Transient Contaminant Dispersion and Ventilation Performance Using the Concept of Accessibility : Energy Buildings 2004;36(3): 293–299 .