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Mémoire (M. Sc. A.)-- Université du Québec à Chicoutimi, 1984. / Bibliographie: f. 101-102. Document électronique également accessible en format PDF. CaQCU

Thesis (M.S.)--University of Wisconsin--Madison, 1967. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (M.S.)--University of Wisconsin--Madison, 1967. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Typescript. Includes vita and abstract. Includes bibliographical references (leaves 110-120). Also available online in Scholars' Bank.

Kinetic data on soot and pyrolytic graphite oxidation rates have been used to calculate the ability of woodstove catalysts to burn woodstove effluent particles. Large variations appear in the literature and depending upon which particle diameter and rates were used one can calculate maximum possible particle oxidation efficiencies of 10⁻¹ to 40 per cent, with most investigators predicting less than a 1 per cent efficiency. This suggests that the 80 per cent reduction in "particulate" emissions which is shown by tests with catalyst-equipped stoves is due to catalytic oxidation of high molecular weight vapors rather than due to particle burnup. Dilute (500 and 250 ppm) acetylene/air mixtures flowing between parallel catalytic plates have been studied experimentally. Measured acetylene profiles for the hydrodynamic entry length region are presented and compared to profiles calculated by a single-phase, two-dimensional, low mass transfer analytical model currently under development and which eventually will be extended to cover three-dimensional flows such as those in the passageways of a woodstove catalyst. The measured temperature profile for a 5000 ppm acetylene/air mixture flowing between parallel catalytic plates was compared to the temperature profile calculated by a single step, adiabatic, constant pressure, homogeneous model. / Master of Science

Two stack loss efficiency measurement methods, the Total Combustible Carbon (TCC) and Combustibles Meter (CM) methods, have been modified for use on masonry heaters. The applicability of the two methods has been verified with 6 tests on two masonry heaters. Each test starts with a cold heater and requires five firings to achieve two different burn rates. The efficiencies calculated for each firing are weighted according to burn rate following EPA Method 28 for wood heaters. The TCC Method uses carbon balances to calculate the chemical energy loss and the dry stack gas mass for calculation of sensible energy loss. The sensible loss that occurs during the off-period, when combustion of wood has stopped, is measured directly by injecting carbon dioxide in the stack and using it as a tracer gas to measure stack flow rate. In both methods the latent energy loss is calculated from wood moisture content and hydrogen content. The CM Method measures losses more directly and is considered the reference method in this work. The chemical energy loss is measured using a flame combustibles meter. The stack flow rate, which is used for the calculation of sensible loss, is measured directly using carbon dioxide tracer gas during both the on and off periods of the appliance. The overall average efficiencies measured by the two methods, in 5 tests on two different appliances, differed by a maximum of 1.7 percentage points of the fuel energy input. On the average they differed by about 1 percentage point. The results of a one-dimensional finite-difference model of the heat exchanger of one of the tested masonry heaters is compared against thermocouple-measured temperatures. For the 3 tests performed the model predicts the measured temperatures to within 12% during the first half of a firing cycle when the burn rate is high, and to within 5% during the second half of the cycle when the burn rate is low. / Master of Science

A laboratory experiment was performed to investigate the interaction between container material and energy source. The energy sources used include: conventional electric coil, gas flame, induction, solid element, and electric resistance coil under glass-ceramic. The container materials investigated include: thin gauge aluminum, heavy gauge aluminum, glass-ceramic, thin gauge porcelain-on-steel, and heavy gauge stainless steel with thick aluminum heat core. Crepes were prepared to determine the browning pattern for each cooking system (combination of energy source and container material). Water was used as a test medium for both speed of heating and retained heat tests. Duncan Multiple Range Tests were performed to determine significant differences between systems, and a General Linear Models Procedure was used to assess the contribution made by each variable on variances between systems. When speed of heating, and retained heat are desired, the important variable was the cooktop. The induction, gas flame, and conventional electric coil boiled water more quickly, and the solid element and the electric resistance coil under glass-ceramic retained the most heat. When even browning is desired, the choice of cookware is important. Heavy gauge aluminum and heavy gauge stainless steel with a thick aluminum heat core produced the most even browning. Systems that performed all tests well include the conventional electric coil paired with heavy gauge aluminum or heavy gauge stainless steel with thick aluminum heat core cookware. / Master of Science

M.S.

The use of biomass as a renewable fuel source can help the United States reduce its dependence on fossil fuels, especially in providing affordable heat for many middle- and low-income households. However, residential wood combustion (RWC) releases pollutants that can negatively impact the environment and human health, especially for those living in the vicinity of wood-burning locations. Current compliance testing methods are insufficient in capturing the actual in-use emissions of residential wood heaters because they do not represent real-life use, leading to higher emissions during actual use. This thesis investigates emissions during realistic operations of wood-fired heaters to identify and quantify the majority of emissions and ways to minimize such emissions. The study focuses on investigating eight different woody biomass fired heaters, including three pellet stoves, a pellet boiler, two wood chip-fired hydronic heaters, and two outdoor cordwood fired hydronic heaters. This research contributes a new knowledge on the impact of combustion strategies, fuel type, and control strategies to minimize emissions. The obtained data can provide information to manufacturers, policy makers, and consumers, guiding low-emission and more efficient use of wood-fired heating devices. In all chapters, variability was evident due to burn phase, fuel type, and operation. The results from the pellet stoves showed that even while using a homogeneous fuel, different burn phases produce different emissions than the overall period. For the pellet boiler studies, the highest efficiencies were achieved during the high load, steady state tests. The burn phase also affects emissions from woodchip boilers, where low output periods are significantly higher in terms of emissions compared to high output periods. Each individual burn phase of the duty cycle produced different emissions in cordwood testing, with steady-state phases having the lowest emissions and highest efficiency. The variability in emissions from different burn phases is a crucial factor in evaluating the performance of wood-burning appliances. Lower moisture content fuels were found to have better performance in terms of PM emissions and efficiency. Fuel type can impact emissions, but it may be overshadowed by burn phase and technology. Relatively high emissions were often related to low or incorrect air-to-fuel ratios. Gasification techniques used in some woodchip boilers during low output periods significantly increased efficiency and reduced CO emissions. Additionally, gasification techniques used during high burn steady states with wet fuel chips resulted in a 77% reduction in PM emissions. Comparing all the primary heaters studied in this thesis, in terms of PM emission output, showed the units that used gasification, integrated catalysts, or thermal storage had the lowest emissions. The results of the study are compiled into data sets that give a more accurate picture of real-world operation of wood-fired heaters that will benefit air quality modelers and policy makers. Such emission data for various biomass heaters in EPA’s AP-42, under realistic operating conditions, currently either does not exist or is limited. Additionally, this research identifies the most important parameters that need to be included in the development of high-resolution models, optimizing the performance of wood-fired devices and supporting the transition from current compliance testing to more realistic testing. In conclusion, this work provides new insights into the performance and emissions of wood-fired heaters during realistic operation. The results of the study can help manufacturers optimize their products for real-life performance and help policy makers and consumers make informed decisions regarding low-emission and more efficient use of wood-fired heating devices. The study highlights the importance of capturing transient phases and the impact of fuel type and control strategies on minimizing emissions.