Browsing by Subject "Particulate matter"
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Item A PM10 emission factor for free stall dairies(Texas A&M University, 2006-08-16) Goodrich, Lee BarryAmbient concentration measurements of total suspended particulate (TSP) were made at a commercial dairy in central Texas during the summers of 2002 and 2003. The facility consisted of both open pen housing and free-stall structures to accommodate approximately 1840 head of milking cattle. The field sampling results were used in the EPA approved dispersion model Industrial Source Complex Short Term version 3 (ISCST-v3) to estimate emission fluxes and ultimately a seasonally corrected emission factor for a free-stall dairy. Ambient measurements of TSP concentrations for sampling periods ranging from 2 to 6 hours were recorded during the summer of 2002. The mean upwind concentration was 115??g/m3 with a maximum of 231??g/m3 and a minimum of 41.4??g/m3. The mean net downwind TSP concentration was 134??g/m3 with a maximum of 491??g/m3 and a minimum of 14??g/m3. Field sampling at this same dairy in the summer of 2003 yielded significantly more 2 to 6 hour TSP concentration measurements. The mean upwind TSP concentration was 76??g/m3 with a maximum concentration of 154??g/m3. The mean net downwind TSP concentration was 118??g/m3 with a maximum of 392??g/m3 and a minimum of 30??g/m3. The particle size distributions (PSD) of the PM on the downwind TSP filters was determined using the Coulter Counter Multisizer. The results of this process was a representative dairy PM PSD with 28% of TSP emissions being PM10. The reported PM10 24-hour emission factors were 4.7 kg/1000hd/day for the free-stall areas of the facility and 11.7 kg/1000hd/day for the open pen areas of the dairy. These emission factors were uncorrected for rainfall events. Corrections for seasonal dust suppression events were made for the San Joaquin Valley of California and the panhandle region of Texas. Using historical rainfall and ET data for central California, the seasonally corrected PM10 emission factor is 3.6kg/1000hd/day for the free-stalls, and 8.7kg/1000hd/day for the open pens. For Texas, the seasonally corrected emission factor is 3.7kg/1000hd/day for the free-stall areas and 9.2kg/1000hd/day for the open lot areas.Item Development, characterization, and modeling of an electronic particulate matter sensor for internal combustion engines(2009-12) Diller, Timothy Thomas; Hall, Matthew JohnU.S. Federal regulations requiring on-board diagnostics of diesel particulate filters have created a demand for compact, inexpensive, fast, and accurate sensors for measuring the particulate matter (PM) content of diesel exhaust. An electronic sensor capable of measuring the carbonaceous fraction (soot) of PM has been developed at The University of Texas at Austin. The behavior and performance of this sensor was characterized in both an older style non-emission controlled diesel engine and a modern heavy-duty diesel certified in 2008 to meet current federal emissions standards. The ability of the sensor to detect particulates at the regulated level of 15 mg/bhp-hr downstream of a leaking particulate filter was demonstrated. Under optimal conditions, the sensor was shown to have a resolution of 0.003 mg/bhp-hr, or 0.005 mg/m3. The sensor operated by measuring the flux of charged particles, ions, and electrons to an electrode immersed in an exhaust gas flow. Two distinct modes of operation were demonstrated. In the first, the sensor detected particles carrying residual charge from the combustion process. In this mode, the sensor was shown to be relatively insensitive to particle morphology and to be sensitive to exhaust gas velocity. In the second, charge carriers (particles, electrons, and ions) were created in the strong electric field produced by a second electrode at high voltage. In this mode, the sensor was found to be relatively insensitive to exhaust gas velocity, but quite sensitive to the orientation of the sensor in the exhaust flow. The size and number density of the particles was found to have a strong influence on the sensor sensitivity: as number density increased with increasing load or decreasing EGR rate, so did sensor sensitivity. Thus, as changes in engine operating condition affect particle morphology, the behavior of the sensor changes. A numerical model of the discharge mechanism in the form of an atmospheric pressure glow discharge was implemented to model the charge creation and transport. The model accurately predicted the nanoamp-level electrode currents produced in a real sensor to within a half order of magnitude with no empirical fits. The model tended to over-predict the sensitivity of sensor output to applied voltage but matched the observed sensitivity within an order of magnitude. Due to the lack of modeling flow field effects it predicted a 250% increase in sensitivity for a gap width reduced by 50% where a comparison of real sensors showed a decrease in sensitivity of 25% with a 50% reduction in gap width.Item Zero to sixty hertz : electrifying the transportation sector and enhancing the reliability of the bulk power system(2015-08) Legatt, Michael Elazar; Baldick, Ross; Webber, Michael EA revolution is underway in the energy sector. Traditional approaches for managing a bulk power system are beginning to give way to a "smart grid" world, in which controllers may have bidirectional communications, with engaged users. At the same time a second transformation has been underway and growing in strength, namely the transition from petroleum as a transportation fuel source towards natural gas for large fleet vehicles, and electricity for consumer vehicles. This thesis focuses primarily on the synergy between the "smart grid" and vehicle electrification transitions. Moving the transportation sector to electricity as a fuel source, at least in Texas, has a myriad of benefits: Charging an electric vehicle without significant growth in renewable or lower-emitting SOFC technologies leads to very significant (80% per mile, 58% per neighborhood) reductions in CO₂ emissions, as well as significant reductions in NO[subscript X] (41% per mile, 17% per neighborhood), PM₁₀ (73% / 62%), PM₂.₅ and UFPM (62% / 55%). SO[subscript X] levels rose by 37%, but could be mitigated with controlled EV charging strategies. Vehicle charging strategies also significantly improved the neighborhood's total emissions profile. Adding in distributed energy resources, microgrid generation and intelligent charging, when optimally allocated, can further reduce these emissions. Vehicle charging schemes that respond dynamically to distributed renewable generation can even be thought of as having zero emissions due to the continual balance of PV generation and EV load on the low side of the distribution transformer. This thesis argues that there may be additionally significant societal benefits by shifting vehicle transportation to electricity, likely far in excess of what could be achieved by controlling power plant emissions alone. Based on an analysis of the ERCOT region, this shift would be expected to produce significant cost reductions for overall energy, improve health (due primarily to the relocation of UFPM far away from major population centers), and lower societal costs. Further gains can be considered as electric vehicles are significantly more energy efficient than their ICE counterparts. Also, on a larger scale, it’s generally easier to reduce emissions from hundreds of fixed power plants than millions of moving ICE vehicles.