Title page for ETD etd-03042009-040837
|Type of Document
||Heffernan, Michael J.
||Evaluation of aged woodstove catalysts
||Master of Science
|Jaasma, Dennis R.
|Nelson, Douglas J.
|Stern, Curtis H.
|Date of Defense
Woodstove emission of atmospheric pollutants has been a growing concern in
the last two decades, and catalytic combustors have been used in woodstoves to reduce
emissions. Field tests of EPA-certified catalytic stoves have demonstrated that
emission factors increase substantially after a few seasons of use, and catalyst
degradation is a suspected cause. Previously, an in-field test developed to assess
catalyst condition was performed on a group of catalytic stoves in field use. In the
current study, a laboratory test apparatus and procedure for the evaluation of
woodstove catalysts was developed to verify the accuracy of the field test. Bench tests
were performed on 24 aged catalysts retrieved from the field-tested stoves. In the
bench test, steady-state conversions of CO and propene were measured at discrete
temperatures ranging from 100°C to 400°C. At a temperature of 400°C, the average
CO conversion of the aged catalysts was 94.8% and the average propene conversion
was 83.1%. Comparison of individual catalyst data did not show a strong correlation
between field measurements and bench test data. It is concluded that inaccuracies in
the field test are responsible for the lack of correlation, and modifications to the field
tests are recommended. In addition to the experimental work, a flow model of a
catalytic woodstove was developed to better understand the interaction between the
combustion process and the fluid mechanics within a woodstove. Evaluations of a
catalytic woodstove under a set of baseline operating conditions show that the catalyst
is not a significant source of frictional pressure loss in a catalytic stove-flue system.
The model also predicts that increasing the flue crosswind velocity from 0 to 5 m/s will
increase the mass flow rate through the stove by 21%.
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