Browsing by Subject "emissions"
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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 Characterization and Combustion Performance of Corn Oil-Based Biofuel Blends(2012-07-16) Savant, Gautam SandeshIn recent years, the development and use of biofuels have received considerable attention due to the high demand for environmentally acceptable (green) fuels. Most of the recent studies have looked at the processes of converting vegetable oils into biodiesel. It is well known vegetable oil to biodiesel conversion involves many processes including transesterification, which makes biodiesel costly and time-consuming to produce. In this study, the effects of blending high-viscosity fresh and used corn oils with low-viscosity diesel and jet fuel mixed with butanol and ethanol were studied. Several corn oil-based blends were formulated and characterized to understand the effect of composition on viscosity, fuel stability and energy content. The formulated corn oil blends were combusted in a 30 kW modified combustion chamber to determine the corresponding NOx and CO emission levels, along with CO? levels. Used corn oil was made by simply heating fresh corn oil for a fixed period of time (about 44 hours), and was characterized by quantifying its total polar material (TPM), iodine value, free fatty acid content, and peroxide value. The combustion experiments were conducted at a constant heat output of 68,620 kJ/hr (19 kW), to observe and study the effects of equivalence ratio, swirl number, and fuel composition on emissions. Used corn oil blends exhibited better combustion performance than fresh corn oil blends, due in part to the higher unsaturation levels in fresh corn oil. NOx emissions for used corn oil increased with swirl number. Among all the blends, the one with the higher amount of diesel (lower amount of corn oil) showed higher NOx emissions. The blend with fresh corn oil showed decreasing NOx with increasing equivalence ratio at swirl number 1.4. All blends showed generally decreasing CO trends at both swirl numbers at very lean conditions. The diesel fuel component as well as the alcohols in the blends were also important in the production of pollutants. Compared to the diesel-based blends mixed with used corn oil, butanol, and ethanol, the jet fuel-based blends showed higher NOx levels and lower CO levels at both swirl numbers.Item Developing a methodology to account for commercial motor vehicles using microscopic traffic simulation models(Texas A&M University, 2004-09-30) Schultz, Grant GeorgeThe collection and interpretation of data is a critical component of traffic and transportation engineering used to establish baseline performance measures and to forecast future conditions. One important source of traffic data is commercial motor vehicle (CMV) weight and classification data used as input to critical tasks in transportation design, operations, and planning. The evolution of Intelligent Transportation System (ITS) technologies has been providing transportation engineers and planners with an increased availability of CMV data. The primary sources of these data are automatic vehicle classification (AVC) and weigh-in-motion (WIM). Microscopic traffic simulation models have been used extensively to model the dynamic and stochastic nature of transportation systems including vehicle composition. One aspect of effective microscopic traffic simulation models that has received increased attention in recent years is the calibration of these models, which has traditionally been concerned with identifying the "best" parameter set from a range of acceptable values. Recent research has begun the process of automating the calibration process in an effort to accurately reflect the components of the transportation system being analyzed. The objective of this research is to develop a methodology in which the effects of CMVs can be included in the calibration of microscopic traffic simulation models. The research examines the ITS data available on weight and operating characteristics of CMVs and incorporates this data in the calibration of microscopic traffic simulation models. The research develops a methodology to model CMVs using microscopic traffic simulation models and then utilizes the output of these models to generate the data necessary to quantify the impacts of CMVs on infrastructure, travel time, and emissions. The research uses advanced statistical tools including principal component analysis (PCA) and recursive partitioning to identify relationships between data collection sites (i.e., WIM, AVC) such that the data collected at WIM sites can be utilized to estimate weight and length distributions at AVC sites. The research also examines methodologies to include the distribution or measures of central tendency and dispersion (i.e., mean, variance) into the calibration process. The approach is applied using the CORSIM model and calibrated utilizing an automated genetic algorithm methodology.Item Efficiency Improvements with Low Heat Rejection Concepts Applied to Low Temperature Combustion(2014-06-25) Penny, MichaelWith increasingly stringent governmental regulations on engine emissions such as oxides of nitrogen (NO_(X)) and particulate matter (PM), there is a strong motivation to decrease the production and release of these harmful substances from internal combustion engines. Simultaneously, there are on-going efforts to increase fuel efficiency to curb usage of natural resources and emission of carbon. In general, improvements in one of these areas comes at the cost of the other; however, the results of a previous computational study have indicated that emissions can be decreased while simultaneously increasing efficiency through the application of low heat rejection (LHR) techniques to low temperature combustion (LTC). The goal of this study is to experimentally confirm these findings using a light duty, multi-cylinder diesel engine. LTC is realized through high levels of exhaust gas recirculation (EGR) and retarded injection timings while different degrees of LHR are achieved by means of higher coolant temperatures which should serve to decrease the temperature gradients across the cylinder walls. An energy balance is conducted on the engine to ensure the validity of the efficiency findings. By applying LHR techniques to LTC operation, the undesirable side effects of LTC were found to be mitigated. Specifically, the emissions of carbon monoxide (CO) and unburned hydrocarbons (HC) were reduced and the loss in engine efficiency was also diminished. NO_(X) and PM emissions did increase but they remained at acceptably low levels. In addition, the results of the energy balance substantiated these trends by properly accounting for the bulk of the input energy. While the full potential of improvements in LTC were not explored due to current engine limitations, these results point to the viability of further research into LHR-LTC concepts.Item Experimental Characterization of Canola Oil Emulsion Combustion in a Modified Furnace(2012-07-16) Bhimani, Shreyas MaheshVegetable oils have been researched as alternative source of energy for many years because they have proven themselves as efficient fuel sources for diesel engines when used in the form of biodiesel, vegetable oil?diesel blends, vegetable oil-water-diesel blends and mixtures thereof. However, very few studies involving the use of emulsified low grade alcohols in straight vegetable oils, as fuels for combustion have been published. Even, the published literature involves the use of emulsified fuels only for compression ignition diesel engines. Through this project, an attempt has been made to suggest the use of alcohol-in-vegetable oil emulsions (AVOE) as an alternate fuel in stationary burners like electric utility boiler producing steam for electricity generation and more dynamic systems like diesel engines. The main goal of this study is to understand the effect of the combustion of different methanol-in-canola oil emulsions, swirl angle and equivalence ratio on the emission levels of NOx, unburned hydrocarbons (UHC), CO and CO2. The 30 kW furnace facility available at Coal and Biomass Energy Laboratory at Texas A & M University was modified using a twin fluid atomizer, a swirler and a new liquid fuel injection system. The swirler blades were positioned at 60? and 51? angles (with respect to vertical axis) in order to achieve swirl numbers of 1.40 and 1.0, respectively. The three different fuels studied were, pure canola oil, 89-9 emulsion [9 percent methanol ? in ? 89 percent canola oil emulsion with 2 percent surfactant (w/w)] and 85-12.5 emulsion [12.5 percent methanol ? in ? 85 percent canola oil (w/w) emulsion with 2.5 percent surfactant]. All the combustion experiments were conducted for a constant heat output of 72,750 kJ/hr. One of the major findings of this research work was the influence of fuel type and swirl number on emission levels. Both the emulsions produced lower NOx, unburned (UHC) hydrocarbon and CO emissions than pure canola oil at both swirl numbers and all equivalence ratios. The emulsions also showed higher burned fraction values than pure oil and produced more CO2. Comparing the performance of only the two emulsions, it was seen that the percentage amount of methanol added to the blend had a definite positive impact on the combustion products of the fuel. The higher the percentage of methanol in the emulsions, the lesser the NOx, UHC and CO emissions. Of all the three fuels, 85-12.5 emulsion produced the least emissions. The vorticity imparted to the secondary air by the swirler also affected the emission levels. Increased vorticity at higher swirl number led to proper mixing of air and fuel which minimized emission levels at SN = 1.4. The effect of equivalence ratio on NO_x formation requires a more detailed analysis especially with regards to the mechanism which produces nitrogen oxides during the combustion of the studied fuels.Item Investigation into the Emissions and Efficiency of Low Temperature Diesel Combustion(2011-10-21) Knight, Bryan MichaelAs global focus shifts towards the health and conservation of the planet, greater importance is placed upon the hazardous emissions of our fossil fuels, as well as their finite supply. These two areas remain intense topics of research in order to reduce green house gas emissions and increase the fuel efficiency of our vehicles. A particular solution to this problem is the diesel engine, with its inherently fuel-lean combustion, which gives rise to low CO2 production and higher efficiencies than its gasoline counterpart. Diesel engines, however, typically exhibit higher nitrogen oxides (NOx [NOx = NO NO2, where NO is nitric oxide and NO2 is nitrogen dioxide]) and soot. There exists the possibility to simultaneously reduce both emissions with the application of low temperature diesel combustion (LTC). While exhibiting great characteristics in simultaneous reductions in nitrogen oxides and soot, LTC faces challenges with higher carbon monoxide (CO) and hydrocarbon (HC) emissions, as well as penalties in fuel efficiency. The following study examines the characteristics of LTC which contribute to the differences in emissions and efficiency compared to typical conventional diesel combustion. More specifically, key engine parameters which are used to enable LTC, such as EGR and fuel pressure are swept through a full range to determine their effects on each combustion regime. Analysis will focus on comparing both combustion regimes to determine how exhaust gas recirculation (EGR) and fuel pressure relate to lowering NO and smoke concentrations, and how these relate to a penalty in fuel efficiency. This study finds that the application of LTC is able to realize a 99 percent reduction in NO while simultaneously reducing smoke by 17 percent compared to the conventional combustion counterpart. Through a sweep increasing EGR, LTC is able to defeat the typical soot ? NO tradeoff; however, brake fuel conversion efficiency decreases 6.8 percent for LTC, while conventional combustion realizes a 4 percent increase in efficiency. The sweep of increasing fuel pressure confirms typical increases in NO and decreases in smoke for both LTC and conventional combustion; however, brake fuel conversion efficiency increases 2.3 percent for LTC and drops 4 percent for conventional combustion.Item Non-Reacting Flow Characteristics and Emissions Reduction on Blends of Coal and Dairy Biomass in 30 kW_(t) Low NO_(x) Down-Fired Furnace(2014-08-07) Tiyawongsakul, TiyawutRecently, coal-fired power plants have considered either to retire themselves or to use natural gas as the main energy source instead of coal due to more stringent air pollution regulations for nitrogen oxides (NO_(x)), mercury (Hg) and more recently the required CO_(2) reduction of 30% by 2030. Clean coal technology must be continuously developed in order to prevent people from losing their jobs and to decrease the negative impacts of firing coal on environment. The present research focuses on NO_(x) emissions which arise mainly due to oxidation of fuel-bound nitrogen using low NO_(x) burner (LNB) when fired with Wyoming Powder River Basin coal (PRB) and blends of coal and dairy biomass (DB). The DB was selected as co-fired fuel for possible elimination of DB from dairy feedlots which result in land, air and water pollution if not properly disposed of. LNB adopts staged air introduction in order to limit the availability of oxygen when nitrogen from fuel is released. To achieve the objective, the mixing patterns between fuel particle and air were predicted using non-reacting flow (NRF) simulation inside the cylindrical combustion chamber. The effects of varying burner parameters, fuel particle sizes, main burner equivalence ratios (ER_(mb)) and overall equivalence ratios (ER_(oa)) on mixing characteristics were investigated. Then, the LNB components were modified based on the results from NRF simulation. The modified main burner is a partially premixed swirl burner (fuel mixes with the primary air inside the fuel/primary air nozzle, and the secondary air is swirled by the straight-vane swirler) whose swirl angle and secondary air swirl number are 59? and 1.42 respectively. The circular over-fire air (OFA) nozzles are located 484 mm below the main burner exit, and the OFA is injected into the combustion chamber in the radial direction. The fuels used in the research were: 1) pure PRB and 2) the fuel blend of PRB and DB with the PRB-to-DB ratio of 90 to 10 on mass basis (90-10 PRB-DB blend). Fuel characteristics were first obtained, and empirical chemical formulae were deduced. The CO_(2), O_(2) and NO were measured as a function of ER_(oa) and ER_(mb) (ER_(mb) based on air flow without inclusion of OFA). The gas analyses were used to obtain the burnt fraction, respiratory quotient (RQ, = CO_(2) moles produced/O_(2) moles consumed) and equivalence ratio which is then checked against measured values. Uncertainty analyses were also performed. The optimum conditions for minimum NO_(x) emission that pass the EPA limit (210 g/GJ) were obtained as follows. With ER_(oa) = 0.95, firing pure PRB produced NO_(x) 220 g/GJ without OFA, and 179 g/GJ with OFA (ER_(mb) = 1.10) which is about 18.6 % reduction. Under same conditions, the co-firing of 90-10 PRB-DB blend decreased NO_(x) by 3.6% without OFA, and 22.2% with OFA (ER_(mb) = 1.10) compared to firing pure PRB at ER_(oa) = 0.95 without OFA. Furthermore, co-firing 90-10 PRB-DB blend with OFA at ER_(mb) = 1.10 and ER_(oa) = 0.95 (excess air 5.26%) emitted NO_(x) approximately 171 g/GJ whilst firing pure PRB without OFA at ER_(oa) = 0.85 (excess air 17.65%) emitted NO_(x) approximately 330 g/GJ which is 48% reduction and less than 210 g/GJ (the current EPA limit). This reduction could benefit 500-MWt power plants approximately $113,500 per year in case the efficiency of power plants is 35% and NO_(x) are traded at $15.89 per short ton.Item Simultaneous Efficiency, NOx, and Smoke Improvements through Diesel/Gasoline Dual-Fuel Operation in a Diesel Engine(2014-08-05) Sun, JiafengDiesel/gasoline dual-fuel combustion uses both gasoline and diesel fuel in diesel engines to exploit their different reactivities. This operation combines the advantages of diesel fuel and gasoline while avoiding their disadvantages, attains spatially stratified low temperature combustion (LTC), and yields very low NOx and PM emissions while maintaining good efficiency. It is promising in solving the problems of conventional LTC through better control of ignition and combustion. The benefits of dual-fuel operation and the potential of using gasoline fumigation to realize these benefits provide the major motivation to this research. This research is aimed at using gasoline fumigation in a medium-duty diesel engine to identify and quantify the influencing factors of diesel/gasoline dual-fuel LTC on engine efficiency and emissions. The factors include gasoline fraction, injection settings, rail pressure, intake pressure, and EGR level. This objective was realized through a series of experimental tests done at 1400 rpm and three loads, including both diesel baseline tests and dual-fuel tests. First, design of experiments and relevant statistical techniques were applied to tests. Twenty-three best models between 6 factors (intake pressure, rail pressure, SOI for diesel baseline tests, SOI for dual-fuel tests, EGR level, and gasoline fraction) and 5 targets (efficiency, NOx, smoke number, HC, and CO) were obtained through regression of test data. Confirmation tests were done based on best models. Generally, the observations are improved NOx and smoke emissions, but unimproved or deteriorated efficiency, HC and CO emissions. The optimization effort makes some achievements, but needs further improvement. The influence of each factor is analyzed. The measures to get better models are explained. Second, parametric studies of gasoline fraction and injection timing were done to find their influence on efficiency and emissions. Efficiency generally decreases slightly as gasoline fraction increases or injection timing is retarded. Generally, increasing gasoline fraction is beneficial for NOx and smoke emissions, but HC and CO emissions deteriorate. An advance in injection timing, however, has the opposite influence. Finally, individual cycle data were analyzed to study cyclic variability (CV) and its influence on dual-fuel efficiency and emissions. Factors causing or influencing CV were identified. The CV in dual-fuel operation is more serious than that in diesel operation, in terms of magnitude. Most of the test data studied do not have strong determinism, and the influence of gasoline addition is small.Item The development and application of a diode-laser-based ultraviolet absorption sensor for nitric oxide(Texas A&M University, 2004-09-30) Anderson, Thomas NathanThis thesis describes the development of a new type of sensor for nitric oxide (NO) that can be used in a variety of combustion diagnostics and control applications. The sensor utilizes the absorption of ultraviolet (UV) radiation by the NO molecule to determine the concentration via optical absorption spectroscopy. UV radiation at 226.8 nm is generated by sum frequency mixing the outputs from a 395-nm external cavity diode laser (ECDL) and a 532-nm diode-pumped, intracavity frequency doubled Nd:YAG laser in a beta-barium borate (BBO) crystal. This radiation is used to probe the (v'=0, v"=0) band of the ?*?+ - ?*? electronic transition of NO. The ECDL is tuned so that the UV radiation is in resonance with a specific energy level transition, and it is then scanned across the transition to produce a fully resolved absorption spectrum. Preliminary experiments were performed in a room-temperature gas cell in the laboratory to determine the accuracy of the sensor. Results from these experiments indicated excellent agreement between theoretical and experimental absorption line shapes as well as NO concentrations. Further experiments were performed at two actual combustion facilities to demonstrate the operation of the sensors in realistic combustion environments. Tests on a gas turbine auxiliary power unit (APU) at Honeywell Engines and Systems and on a well-stirred reactor (WSR) at Wright-Patterson Air Force Base produced excellent results despite the harsh temperatures and vibrations present. Overall, the sensitivity was estimated to be 0.8 parts per million (ppm) of NO (at 1000 K) for a 1 meter path length and the measurement uncertainty was estimated to be ?10%.