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Author
Title Modeling contaminant spread and mitigation in the indoor environment
URL
Publication Date
Date Accessioned
Degree PhD
Discipline/Department 0133
Degree Level doctoral
University/Publisher University of Illinois – Urbana-Champaign
Abstract Experimental and modeling efforts, using a pilot-scale testbed and multizone modeling, are undertaken to develop filtration and ventilation strategies aimed at improving indoor air quality (IAQ). As part of this effort, a model is developed to effectively estimate crack areas of the multizone testbed. The model is divided into two sub-approaches: one approach is to assume the same crack area for the same type of opening and determine them by minimizing the sum of the squares of relative error between the calculated and experimental ventilation rates for the whole facility; the other is to assume that the crack areas are independent of each other and a similar least-squares minimization is applied to determine these crack areas zone by zone. A comparison of the two approaches shows that both can provide satisfactory results, and the latter approach is preferred, because it provides more flexibility and detail. Ventilation systems are explored using multizone simulations. The model results suggest a distributed unbalanced ventilation system is preferred for maintaining IAQ, because 1) it can provide positive pressure difference across the building envelope to prevent exterior contaminant infiltration; and 2) some contaminated indoor zones can be “isolated” from adjacent ones by adjusting the relative pressure differences. Realistic particle distributions typical to a particular contamination threat of interest are considered, and an acoustically enhanced impaction (AEI) filtration device is investigated together with other filters. The protection factor (PF, a ratio of concentration integrated over time in the ambient to that indoors) is chosen as a performance metric. A PF-oriented evaluation framework has been established such that ventilation system/strategy (or filter) comparison in terms of IAQ enhancement is straightforward. For instance, 16 filtration schemes are compared to identify preferred ventilation and filtration strategies. For the indoor environment, a highly efficient outside air (OA) filter is recommended, but a recirculated air (RA) filter is relatively much less effective. For vestibule protection, a stand-alone balanced system with 100% RA filtration is recommended. The AEI device can be an alternative to a HEPA filter when the ambient contamination level is low to moderate. Extension of an existing analytical steady-state PF model is undertaken to demonstrate the advantages of pressurization protection of buildings over non-pressurization protection. The analytical PF model can be used to determine the ventilation flow rate and filter efficiency at a specific PF level and guide the vestibule door operation. It is found that the minimum closing period of the vestibule interior door typically should be 20 minutes to protect the room.
Subjects/Keywords Indoor Air Quality; Contaminant mitigation; Pressurization protection; Crack estimation; Protection factor; CONTAM
Contributors Jacobi, Anthony M. (advisor); Jacobi, Anthony M. (Committee Chair); Bullard, Clark W. (committee member); Hrnjak, Predrag S. (committee member); Wang, Xinlei (committee member)
Language en
Rights Copyright 2014 Lingjun Meng
Country of Publication us
Record ID handle:2142/49619
Repository uiuc
Date Indexed 2018-11-19
Grantor University of Illinois at Urbana-Champaign
Issued Date 2014-05-30 16:52:41

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…three plans for the DUBVS ......................................................... 111 Table D.6 Comparison of the analytical relationships and CONTAM simulations ................... 112 ix LIST OF SYMBOLS English Symbols Acrack leakage area (…

…and CONTAM, a multizone indoor air quality and ventilation analysis software package developed by the National Institute of Standards and Technology (NIST). Particle transport involves a number of complicated phenomena and processes. In the…

…areas in a multizone building based on supply air flow rates and pressure differences across the building shell; 2) exploring ventilation and filtration strategies to select the best ventilation system and filtration schemes using CONTAM; and 3)…

…and exterior leakage is highly desirable. CONTAM has been utilized to predict ventilation flow rate and contaminant concentration (ASHRAE, 2009). However, further empirical and/or inter-model comparisons are needed to fully demonstrate the…

…validity and reliability of CONTAM (ASHRAE, 2009). 1.2.2 Contaminant Mitigation In order to mitigate indoor contamination, it is important to know the building leakage for any pressure difference across the building envelope, because air…

…Liddament and Allen, 1983; Feustel and Kendon, 1985) since Jackman (1970) published the first one, LEAK. There are currently two well-known and publically accessible multizone simulation tools. The first one is called CONTAM, which is…

…ventilation after identifying the limitations of the two. Lorenzetti (2002b) also investigated computational aspects of multizone airflow systems, and found that CONTAM and COMIS were better programmed, following a series of underlying assumptions to…

…selected in order to maintain a specific indoor PF level?” The multizone simulation software CONTAM is a suitable tool for exploring such a question, provided that filter efficiency curves, ambient particle distribution, building leakage area, and…

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