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Title:Characterizing the dynamics of a multizone enclosure by identifying unknown system parameters using tracer gas techniques and least squares identification algorithms
Author(s):O'Neill, Patrick J.
Department / Program:Mechanical Engineering
Discipline:Mechanical Engineering
Degree Granting Institution:University of Illinois at Urbana-Champaign
Degree:Ph.D.
Genre:Dissertation
Subject(s):Engineering, Mechanical
Abstract:This work presents and evaluates a new method, based upon tracer gas techniques, for determining interzonal airflows and effective volumes in a multizone enclosure. Presently used tracer gas techniques have a number of drawbacks including the need for multiple tracers when analyzing a multizone structure. The proposed method uses a single tracer gas to disturb the zones. A state-space formulation is used to model the multizone system. The concentration data are used in combination with a recursive least-squares identification algorithm to determine all of the interzonal airflows and effective volumes. A number of simulations are then used to evaluate the method. The simulations show that there are important considerations when selecting the type of input applied to each zone. They also indicate that the proper choice of sampling interval is critical for accurate identification.
A three-zone experimental test facility was also constructed to validate the simulation results as well as test the identification algorithms under more realistic conditions. The results indicate that the single gas tracer technique was able to estimate the interzonal airflows and effective volumes of the experimental facility to within 10%, in most cases.
Three methods are proposed and evaluated for analyzing systems in which non-ideal mixing of the tracer inputs occur. The method of choice in most cases is to compensate for inadequate mixing by varying the sampling interval. However, the time constants of the system limit the maximum sampling interval. A second method is zone subdivision. This method suffers from the drawbacks of requiring additional tests and equipment. The third method is to alter the system model to include non-ideal mixing. The injection cell modelling technique is proposed for cases where sampling interval compensation and zone subdivision are not appropriate. The injection cell technique divides each zone into two cells-an injection cell and a detection cell. This modelling technique permits estimation of airflows and total volumes in cases where the tracer inputs mix slowly, relative to the time constants of the system.
Issue Date:1990
Type:Text
Language:English
URI:http://hdl.handle.net/2142/22031
Rights Information:Copyright 1990 O'Neill, Patrick J.
Date Available in IDEALS:2011-05-07
Identifier in Online Catalog:AAI9114366
OCLC Identifier:(UMI)AAI9114366


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