Browsing by Author "Olsen, Daniel B., advisor"
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Item Open Access Analysis and refinement of Methane Number test procedure for gaseous fuels(Colorado State University. Libraries, 2024) Baucke, Dawson, author; Olsen, Daniel B., advisor; Wise, Daniel M., committee member; Daily, Jeremy S., committee memberMethane Number (MN) is an experimentally determined parameter for quantifying the resistance of gaseous fuels to End Gas Auto Ignition (EGAI). Originating from Leiker et al. in Graz, Austria, MN was introduced as an alternative to traditional gasoline rating techniques due to limitations on maximum obtainable values without extrapolative methods. Through funding provided to AVL, Leiker, et al. explored the impact of gas composition on fuel reactivity, although the specific details of their testing method remain unpublished. Subsequently, refinements to Leiker's proposed analytical method were made by AVL and MWM including digitizing of the AVL experimental data and the use of a computer program. The American Society of Testing Materials (ASTM) developed a standard for calculating a methane number (MNC)based on the gaseous fuel composition using the latest MWM methodology and experimental data. Amidst growing interest in renewable and hydrogen-blended natural gas, uncertainties within the experimental data used in the MNC method have spurred re-evaluation of the MN testing method. The purpose of this research is to create a repeatable method for determining the knock resistance of gaseous fuels analogous to the methods used for gasoline utilizing reference fuel blends of methane, hydrogen, and carbon dioxide. While Leiker, et al. did not disclose details of their MN quantification testing method, numerous research groups have developed their own methods, often without divulging test specifics or operating conditions. Presently, there is no standardized method for experimentally determining the MN of a gaseous fuel. This study aims to establish and share a repeatable method for MN determination using a modified Cooperative Fuel Research Engine (CFR). The investigation includes justification of allowable environmental parameters and operating variation limits, as well as exploring potential adaptations to the original proposed method. A pivotal aspect of the MN method involves identifying and quantifying a Knock Index (KI) parameter during engine operation, a challenge tackled through various approaches. CFR engines, originally designed for gasoline EGAI testing, come equipped with their own knock detection measurement systems. CSU has devised its method for determining a KI, and a comparison between the two systems was conducted to facilitate the publication of a standardized MN testing protocol.Item Open Access Analysis of industrial oilseeds: production, conversion to biofuels, and engine performance from large to small scale(Colorado State University. Libraries, 2015) Drenth, Aaron C., author; Olsen, Daniel B., advisor; Johnson, Jerry J., advisor; Cabot, Perry E., committee member; Schaeffer, Steven L., committee memberMost of the biofuel produced in the U.S. as an alternative to petrodiesel is derived from soybean oil. Three major problems of using soy and other traditional biofuel feedstocks are: (1) the high commodity cost of the feedstock results in higher cost fuel than the petroleum equivalent, (2) land use requirements are too great to offset a significant portion of petroleum use, and (3) many traditional biofuel feedstocks also have food uses, which creates market competition and a “food versus fuel” debate. The problems above are addressed by exploring the feasibility of biofuel production from a new class of oilseeds known as industrial oilseeds, and industrial corn oil as a biofuel feedstock. Industrial oilseeds are alternative low-cost oilseeds also known in the literature as low-impact oilseeds or non-food oilseeds. Due to their non-food nature, they steer us clear of any food versus fuel debates. They have several advantages over conventional oilseeds, such as a short growing season, high oil yield and quality, ability to thrive on marginal lands, and low water and fertilizer inputs. These advantages can equate to lower oil costs. Since these oils can be optimized for fuel instead of food, plant scientists can maximize the erucic and other long chain fatty acids, which increase fuel conversion rates and fuel quality. For several of these plant species, little or no engine research has been done; some in the agronomic community still consider some of these plants weeds. This research includes compression ignition engine performance and emissions studies, measurement of important fuel properties, and investigation into the feasibility of several fuel pathways. Corn is not classified as an oilseed by the USDA; however, the corn kernel contains a small amount of oil (~3.5%) which can be extracted during the production of ethanol. Only the starch portion of a corn kernel is converted to ethanol; the remaining solids (including the oil) remain in the distillers grain coproduct. Recently, the ethanol industry has discovered economical methods to extract this corn oil from the meal stream. As corn oil extraction technology has matured and ethanol margins have tightened, the ethanol industry has started widely adapting this technology as an additional revenue-generating coproduct. Since most ethanol plants are non-food grade facilities, corn oil from an ethanol plant can also be categorized as an industrial oilseed. Corn oil represents a relatively new, abundant, and inexpensive source of biofuel feedstock. This research includes compression ignition engine performance and emissions of corn oil based fuels, feasibility of using corn oil as an on-farm biofuel feedstock, research into fuel production and processing methods, and measurement of important fuel properties.Item Open Access Conversion of low BMEP 4-cylinder to high BMEP 2-cylinder large bore natural gas engine(Colorado State University. Libraries, 2016) Ladd, John, author; Olsen, Daniel B., advisor; Petro, John, committee member; Bienkiewicz, Bogusz, committee memberThere are more than 6,000 integral compressor engines in use on US natural gas pipelines, operating 24 hours a day, 365 days a year. Many of these engines have operated continuously for more than 50 years, with little to no modifications. Due to recent emission regulations at the local, state and federal levels much of the aging infrastructure requires retrofit technology to remain within compliance. The Engines and Energy Conversion Laboratory was founded to test these retrofit technologies on its large bore engine testbed (LBET). The LBET is a low brake mean effective pressure (BMEP) Cooper Bessemer GMVTF-4. Newer GMV models, constructed in 1980’s, utilize turbocharging to increase the output power, achieving BMEP’s nearly double that of the LBET. To expand the lab’s testing capability and to reduce the LBET’s running cost: material testing, in-depth modeling, and on engine testing was completed to evaluate the feasibility of uprating the LBET to a high BMEP two cylinder engine. Due to the LBET’s age, the crankcase material properties were not known. Material samples were removed from engine to conduct an in-depth material analysis. It was found that the crankcase was cast out of a specific grade of gray iron, class 25 meehanite. A complete three dimensional model of the LBET’s crankcase and power cylinders was created. Using historical engine data, the force inputs were created for a finite element analysis model of the LBET, to determine the regions of high stress. The areas of high stress were instrumented with strain gauges to iterate and validate the model’s findings. Several test cases were run at the high and intermediate BMEP engine conditions. The model found, at high BMEP conditions the LBET would operate at the fatigue limit of the class 25 meehanite, operating with no factor of safety but the intermediate case were deemed acceptable.Item Open Access Dedicated exhaust gas recirculation applied to a rich burn industrial natural gas engine(Colorado State University. Libraries, 2020) Van Roekel, Chris, author; Olsen, Daniel B., advisor; Jathar, Shantanu, committee member; Marchese, Anthony, committee member; Young, Peter, committee memberRich burn natural gas engines provide power for industrial applications such as gas compression. In this application where exhaust oxides of nitrogen (NOx) requirements can be critical, rich burn engines offer best in class aftertreatment emission reduction and operating cost capabilities by using a non-selective catalyst reduction (NSCR) or three-way catalyst system. However, due to high combustion temperatures associated with near stoichiometric air-fuel ratio (AFR) operation, rich burn engines are limited in brake mean effective pressure (BMEP) by combustion temperature. Consumers in the gas compression application are left to choose between engines that are capable of meeting even the most stringent emission requirements (rich burn) and engines with high BMEP rating (lean burn). Charge dilution by way of excess air (lean burn) or exhaust gas recirulation (EGR) is a common method used to lower combustion temperature with the purpose of limiting the production of engine out NOx. Conventional configurations of EGR consist of high pressure loop (HPL) and low pressure loop (LPL), each of which rely on components exposed to relatively high temperatures to control the impact that EGR has on combustion. Dedicated EGR is a novel variant of conventional EGR configurations which allows for the impact that EGR has on combustion to be controlled by components exposed to ambient temperature natural gas while also lowering rich burn combustion temperatures. Due to the lack of published research on dedicated EGR applied to industrial natural gas engines and consumer driven need for technologies to increase rich burn industrial natural gas engine BMEP this work represents an initial investigation into challenges associated with and capabilities of dedicated EGR. A Chemkin chemical kinetics model using the SI Engine Zonal, Flame Speed Calculator, and Equilibrium models was developed to quantify dedicated cylinder exhaust composition, laminar flame speed, and equilibrium combustion composition, respectively. The Aramco 2.0 mechanism was used for natural gas kinetics and was modified to include Zel'dovich mechanism for NOx formation. Engine experiments were conducted using a Caterpillar G3304 rich burn natural gas engine modified to operate with and without dedicated EGR. Initial tests that included power sweeps at fixed dedicated cylinder AFR revealed that operating conditions appropriate for dedicated EGR gasoline engines were not suitable for dedicated EGR natural gas engines. A response surface method (RSM) optimization was performed to find improved operating conditions at part load, 3.4 bar BMEP. Results showed that advanced spark timing and slightly rich dedicated cylinder AFR were optimal to achieve decreased coefficient of variance of indicated mean effective pressure (COV IMEP) and balanced cylinder IMEP output. In order to assess how operating with dedicated EGR would affect the performance of a NSCR system at 6.7 bar BMEP and fixed operating conditions engine AFR was swept between rich and lean conditions to quantify catalyst reduction efficiency and find the emissions compliance window. Without intentional AFR dithering the emissions compliance window was increased significantly. Finally, using best operating conditions from the RSM optimization and engine AFR sweep tests engine BMEP was increased beyond the 6.7 bar rating to find the possible increase in power density resulting from dedicated EGR.Item Open Access Dual fuel engine combustion and emissions - an experimental investigation coupled with computer simulation(Colorado State University. Libraries, 2014) Wan Mansor, Wan Nurdiyana, author; Olsen, Daniel B., advisor; Marchese, Anthony J., committee member; Xinfeng, Gao, committee member; Sharvelle, Sybil, committee memberAlternative fuels have been getting more attention as concerns escalate over exhaust pollutant emissions produced by internal combustion engines, higher fuel costs, and the depletion of crude oil. Various solutions have been proposed, including utilizing alternative fuels as a dedicated fuel in spark ignited engines, diesel pilot ignition engines, gas turbines, and dual fuel and bi-fuel engines. Among these applications, one of the most promising options is the diesel derivative dual fuel engine with natural gas as the supplement fuel. This study aims to evaluate diesel and dual fuel combustion in a natural gas-diesel dual fuel engine. More dual fuel engines are being utilized due to stricter emission standards, increasing costs of diesel fuel and decreasing costs of natural gas. Originally sold as diesel engines, these units are converted to natural gas-diesel fuel engines using an aftermarket dual fuel kit. As natural gas is mixed with air intake, the amount of diesel used is reduced. The maximum natural gas substitution is limited by knock or emissions of carbon monoxide and total hydrocarbons. In this research a John Deere 6068H diesel engine is converted to dual fuel operation. The engine is a Tier II, 6 cylinder, 6.8 liter, 4-stroke compression ignition engine with a compression ratio of 17:1 and a power rating of 168 kW at 2200 rpm. A natural gas fuel system is installed to deliver fuel upstream of the turbocharger compressor. The engine operates at 1800 rpm through five different load points in diesel and dual fuel operating modes. Crank angle resolved high speed combustion pressure data is obtained and analyzed. The natural gas substitution values tested are representative of standard dual fuel tuning, with a maximum diesel displacement of 70%. Data for thermal efficiency, combustion stability, in-cylinder pressure and net heat release rate are also presented in this study. In addition, fuel consumption and pollutant emissions are measured. Elevated CO and HC emissions are observed at low loads for dual fuel operation. Overall, CO and unburned HC emissions increase for dual fuel operation. However, the average levels of PM and NOx substantially decreases. A series of natural gas and injection timing sweep are conducted to optimize the combustion and emission in dual fuel engine. To understand the location of emissions inside the cylinder, a model study of a natural gas-diesel dual fuel combustion and emission is performed using the commercial CONVERGE CFD code. A reduced chemical kinetic mechanism with 86 species and 393 reactions for n-heptane, methane, ethane and propane is used. A preliminary hypothesis for these emissions is formulated based on the values of experiment equivalence ratio. Findings indicate that a large amount of CO and HC emissions in dual fuel engines are mainly located on the cylinder wall and nozzle area. High temperatures are not able to propagate through the lean mixture of natural gas and air in dual fuel engine hence high unburned fuel trapped at wall. It is concluded that dual fuel engines are capable of reducing emissions and cost saving (through diesel displacement up to 70%) in diesel fuel engines. CO and unburned HC can be reduced with the application of a dual fuel optimization map. Further investigation using oxidation catalyst is recommended in order to meet with emission regulations.Item Open Access Evaluation of advanced air-fuel ratio control strategies and their effects on three-way catalysts in a stoichiometric, spark ignited, natural gas engine(Colorado State University. Libraries, 2021) Jones, Andrew Lawrence, author; Olsen, Daniel B., advisor; Marchese, Anthony, committee member; Johnson, Jerry, committee memberEngine emissions are a growing concern in the 21st century. As the world works to combat rising pollution levels, engine emissions are under scrutiny. Natural gas engines are increasing in popularity over diesel engines, due to the high availability of fuel and fewer pollutant emissions than comparable diesel engines. Pollutants such as NOx, CO, and THCs (total hydrocarbons) are harmful to the environment and are currently regulated, and limits for these pollutants are expected to decrease further in the future. A three-way catalyst (TWC) is a cost-effective exhaust after treatment system can be used to reduce pollutant emissions through a series of reactions that are catalyzed by special conditions within the catalyst. Using TWCs, emissions can be drastically reduced using simple chemical reactions, without affecting engine performance. Air-fuel ratio dithering is a strategy that can be used to increase catalyst reduction efficiency by utilizing the oxygen storing properties of ceria, a material in the catalyst washcoat. Dithering is a method of periodically varying the air-fuel ratio of the engine around an optimum point. The focus of this work is understanding how dithering affects oxygen storage in a catalyst, as well as how dithering amplitude and frequency can be tuned to maximize catalyst efficiency. Experiments were performed on a CAT CG137-8, a stationary natural gas engine used for gas compression. Three different catalysts were tested, including the standard catalyst for the test engine, a custom catalyst with one half of the oxygen storage capability of the standard catalyst, and the standard catalyst artificially aged to 16,000 hours. Emissions data were collected across a dithering parameter sweep where a large number of amplitude and frequency combinations were tested. Additionally, steady state and dithering air-fuel ratio sweeps were performed to investigate the emissions window of compliance across a wide range of air-fuel ratios. It was found that dithering with optimized amplitude and frequency can significantly reduce pollutant emissions with a fresh catalyst. However, dithering does not have a large effect on aged catalysts. Additionally, dithering was shown to improve the window of emissions compliance on a standard catalyst by 100% but showed a smaller improvement on a catalyst with ½ oxygen storage capability. The window of compliance with an aged catalyst was unimproved by dithering. Optimized dithering has the potential to significantly reduce engine emissions, allowing for compliance with more stringent emissions requirements or for less expensive catalysts to be used.Item Open Access Evaluation of controlled end gas auto ignition with exhaust gas recirculation in a stoichiometric, spark ignited, natural gas engine(Colorado State University. Libraries, 2020) Bayliff, Scott Michael, author; Olsen, Daniel B., advisor; Windom, Bret, committee member; Baker, Daniel, committee memberMany stationary and heavy-duty on-road natural gas fueled engines today operate under stoichiometric conditions with a three-way catalyst. The disadvantage of stoichiometric natural gas engines compared to lean-burn natural gas and diesel engines is lower efficiency, resulting primarily from lower power density and compression ratio. Exhaust gas recirculation (EGR) coupled with advanced combustion controls can enable operation with higher compression ratio and power density, which yields higher efficiency. This also results in engine operation between the limits of knock and misfire. Operation between these limits has been named controlled end gas auto-ignition (C-EGAI) and can be used to improve the brake efficiency of the engine. Various methods of cylinder pressure-based knock quantification were explored to implement C-EGAI. The indicated quantification methods are used for the implementation of a control scheme for C-EGAI with a relation to the fractional heat release due to auto-ignition. A custom EGR system was built and the effect of EGR on the performance of a stoichiometric, spark ignited, natural gas engine is evaluated. C-EGAI is implemented and the optimal parameters are determined for peak performance under EGR and C-EGAI conditions. In this study, knock detection is used for the recognition, magnitude, and location of the auto-ignition events. Cylinder pressure-based knock detection was the primary method for determining the occurrence and location of knock but was also used for implementing the ignition control scheme for controlled end gas auto-ignition. The combustion intensity metric (CIM) enabled parametric ignition timing control which allowed for the creation of a relationship between fractional heat release due to auto-ignition and CIM. Both exhaust gas recirculation and controlled end gas auto-ignition were analyzed with a cooperative fuel research (CFR) engine modified for boosted fuel/air intake. The data was interpreted to provide a proper evaluation of unique analytical methods to quantify the results of C_EGAI and characterize the live auto-ignition events. The control variables for this method of C-EGAI were optimized with EGR conditions to generate the point of peak performance on the CFR engine under stoichiometric, spark ignited, natural gas conditions.Item Open Access Evaluation of ethanol substitution in a compression ignition engine(Colorado State University. Libraries, 2017) Van Roekel, Chris, author; Olsen, Daniel B., advisor; Bandhauer, Todd, committee member; Reardon, Ken, committee memberHeavy duty compression ignition engines rely on advanced emission control strategies to mitigate regulated emissions in compliance with requirements set by the Environmental Protection Agency. These strategies add significant cost and complexity to engine design. Previous work identified that a diesel-ethanol dual fuel combustion technique may be able to reduce diesel fuel consumption and supplement current emission control methods. The substitution of diesel fuel with a renewable, U.S. based fuel such as corn ethanol would also improve US energy security. A review of diesel-ethanol dual fuel combustion identified five possible methods of diesel-ethanol dual fuel combustion. They were ethanol-diesel emulsions, ethanol-diesel-additive blending, twin direct injection of ethanol and diesel, ethanol fumigation of intake air with standard diesel fuel injection, and full substitution of diesel with ethanol. Analysis of ethanol-diesel emulsions and ethanol-diesel-additive blending concluded that only low volumes of ethanol (<10%) could be blended in diesel fuel before the two fuels were immiscible. However, analysis using ternary phase diagrams showed that additives such as B100 biodiesel could be used to extend the substitution limit significantly such that at 25°C mixtures of 80% 200 proof ethanol, 10% B100 biodiesel, and 10% off-road diesel were visibly miscible. Miscible mixtures containing high volumes of ethanol underwent further analysis, which showed that these fuels were not suitable drop in replacements for diesel fuel due to poor cold flow properties. Based on fuel blending analysis and previously published literature ethanol fumigation of intake air was selected for an on-engine demonstration using a Cummins 6.7L QSB Tier 4 Final engine. Three ethanol based fuels were selected for this dual fuel combustion work: 200 proof ethanol, 190 proof ethanol, and a blend of 15% E0 gasoline and 85% 200 proof ethanol. Pre and post aftertreatment emission data and high speed combustion data were collected while operating the engine at ISO 8178 test points C1-7, C1-3, and C2-4. The maximum diesel substitution at each test point was similar among the three test fuels. and at moderate to high engine loads diesel substitution was limited to 25% and 39%, respectively due to engine knock . At low engine loads substitution was limited to 25% by exhaust emission requirements. Premixed ethanol combustion increased brake specific efficiency at moderate and high engine loads by 3% and 3.2%, respectively, but reduced efficiency at low engine loads by 1.4%. Finally, although the complete ISO 8178 test map was not completed the Tier 4 Final after treatment system was able to reduce ethanol premixed combustion emissions to at or below the diesel baseline emissions at nearly every test point.Item Open Access Expanding the knock/emissions limits for the realization of ultra-low emissions, high-efficiency heavy-duty natural gas engines(Colorado State University. Libraries, 2023) Rodriguez Rueda, Juan Felipe, author; Olsen, Daniel B., advisor; Windom, Bret, committee member; Baker, Daniel, committee member; Quinn, Jason, committee memberHeavy-duty on-highway natural gas (NG) engines are a promising alternative to diesel engines to reduce greenhouse gas and harmful pollutant emissions if the limitations (knock and misfire) for achieving diesel-like efficiencies are addressed. This study shows innovative technologies for developing high-efficiency stoichiometric, spark-ignited (SI) natural gas engines. To develop the base knowledge required to reach the desired efficiency, a Single Cylinder Engine (SCE) is the most effective platform for acquiring reliable and repeatable data. An SCE test cell was developed using a Cummins 15-liter six-cylinder heavy-duty engine block modified to fire one cylinder (2.5-liter displacement). A Woodward Large Engine Control Module (LECM) is integrated to permit real-time advanced combustion control implementation. Fixed location of 50% burn and Controlled End Gas Auto-Ignition (C-EGAI) were used to define the ignition timing. C-EGAI allows operation with an optimized fraction of end gas auto-ignition combustion. Intake and exhaust characteristics, fuel composition, and exhaust gas recirculated substitution rate (EGR) are fully adjustable. A high-speed data acquisition system acquires in-cylinder, intake, and exhaust pressure for combustion analysis. Further development includes advanced control methodologies to maintain stable operation and higher dilution tolerance. Controlled end-gas autoignition (C-EGAI) is used as a combustion control strategy to improve efficiency. A Combustion Intensity Metric (CIM) is used for ignition control while operating the engine under C-EGAI. During the baseline testing of the developed SCE test cell, effective control of intake manifold pressure, exhaust manifold pressure, engine equivalence ratio, speed, torque, jacket water temperature, and oil temperature was demonstrated. The baseline testing shows reliable and consistent results for engine thermal efficiency, indicated mean effective pressure (IMEP), and coefficient of variance of the IMEP over a wide range of operating conditions. High Brake Thermal Efficiency (BTE) was achieved using improved hardware and a high EGR rate. Due to the correlation of CIM to the fraction of EGAI (f-EGAI), CIM was used as the reference variable to implement C-EGAI. Achieving conditions of C-EGAI allowed for the utilization of high EGR at high IMEP without inducing knock. The operation of the engine under these conditions showed peak brake thermal efficiency above 46% using an EGR ratio of 30% The work described proves the concept of using new and innovative control algorithms and CFD-optimized combustion chamber designs, allowing ultra-high efficiency and low emissions for NG ICE's heavy-duty on-road applications.Item Open Access Experimental & analytical evaluation of knock characteristics of producer gas(Colorado State University. Libraries, 2010) Arunachalam, Aparna, author; Olsen, Daniel B., advisor; Marchese, Anthony, committee member; Sharvelle, Sybil E., committee memberAmongst the popular gaseous bio-fuels is producer gas. Evaluation of knock properties of producer gas enhances efficient utilization of this renewable energy resource in an internal combustion engine. A literature review revealed that producer gas is formed from a set of combustion-reduction reactions in a gasifier and is typically composed of 18-20% H2, 18-20%CO, 2-3% CH4, 12% CO2 and 48-50%N2. It is seen that a production process where the combustion and reduction reactions are effectively separated yields a gas rich in hydrogen. Hence based on the production method and range in gas composition five different producer gas compositions are chosen for knock evaluation. Knock evaluation for gaseous fuels has been done by previous researchers using the Methane Number method. This method requires the use of a Cooperative Fuel Research (CFR) F2 engine installed in Colorado State University’s Engines and Energy Conversion Laboratory. It was seen that the methane number of producer gas ranged from 54-131. Further it was quantitatively evaluated that addition of CO2 increases the critical compression ratio while H2 decreases it. Overall, the effect of CO2 on changing the critical compression ratio was found to be over twice that of H2. It was attempted to evaluate the methane number of producer gas using chemical kinetics software CHEMKIN. A Methane Number evaluation process was developed using CHEMKIN’s internal combustion engine model. There were significant differences between model and experiment. Recommendations for future work are discussed.Item Open Access Experimental and CFD investigation of re-agent mixing in an SCR system(Colorado State University. Libraries, 2007) Ivaturi, Krishna, author; Olsen, Daniel B., advisor; Mitchell, Charles E., committee member; Meroney, Robert, committee memberNitrogen oxides (NOx) cause a gamut of problems such as harmful particulate matter, ground level ozone (smog) and acid rain. Currently, a significant capital is being invested researching new techniques to control NOx emissions. One of the best ways to breakdown NOx is the Selective Catalytic Reduction (SCR) after-treatment method. A reducing agent (re-agent) is injected into exhaust gases and passed through a catalyst that facilitates NOx breakdown into Nitrogen and Water. To ensure effective NOx conversion, there must be uniform mixing between re-agent and exhaust gas upstream of the catalyst blocks. The current thesis focuses on investigating the mixing quality for an SCR test system employed for a 2-stroke lean-bum natural gas engine. CFD investigations were conducted to simulate the physical flow process. The mixing quality for different injector locations and the effect of utilizing a downstream in-line mixer was investigated. The CFD simulations were compared to experimental results. To measure ammonia concentrations experimentally, a traversing probe was designed and built. Re-agent concentrations were measured at various locations on a plane slightly upstream of the catalyst substrate. Detailed discussion is presented on different cases of CFD analysis. Experiments were conducted for the best and worst case of mixing based on CFD computation. Results suggest that a mixer plays a vita1 role in improving the mixing.Item Open Access Hydrogen-natural gas fuel blending and advanced air fuel ratio control strategies in a "rich burn" engine with 3-way catalyst(Colorado State University. Libraries, 2023) Katsampes, Nicholas, author; Olsen, Daniel B., advisor; Thorsett-Hill, Karen, committee member; Sharvelle, Sybil, committee memberInterest in hydrogen (H2) fuels is growing, with industry planning to produce it with stranded or excess energy from renewable sources in the future. Natural gas (NG) utility companies are now taking action to blend H2 into their preexisting pipelines to reduce greenhouse gas (GHG) emissions from burning NG. "Rich burn" (stoichiometric) engines with 3-way catalysts are not typically used with H2-NG blending; however, many of these engines operate on pipeline NG and will receive blended fuel as more gas utilities expand H2 production. These engines are typically chosen for their low emissions owing to the 3-way catalyst control, so the focus of this paper is on the change in emissions like carbon monoxide (CO) and nitrogen oxides (NOx) as the fuel is blended with up to 30% H2 by volume. The Caterpillar CG137-8 natural gas engine used for testing was originally designed for industrial gas compression applications and is a good representative for most "rich burn" engines used across industry for applications such as power generation and water pumping. Results indicate a significant reduction in greenhouse gas (GHG) emissions as more H2 is added to the fuel. Increasing H2 in the fuel changes combustion behavior in the cylinder, resulting in faster ignition and higher cylinder pressures, which increase engine-out NOx emissions. Pre-catalyst emissions behave as expected; CO decreases and NOx increases. Unexpectedly, post-catalyst CO and NOx both decrease slightly with increasing H2 while operating at the optimal "air-fuel" equivalence ratio (λ or "lambda"). This testing shows that a "rich burn" engine with 3-way catalyst can tolerate up to 30% H2 (by vol.) while still meeting NOx and CO emissions limits. However, this research found that at elevated levels of H2, increased engine-out NOx emissions narrow the λ range of operation. As H2 is added to NG pipelines, some "rich burn" engine systems may require larger catalysts or more precise λ control to tolerate the increased NOx production associated with a H2-NG blend. This paper includes additional investigation into transitioning H2 concentrations. Sudden step-increases in H2 cause dramatic changes in λ, resulting in large emissions of post-catalyst NOx during the transition. Comparable changes in H2 at elevated concentrations cause larger spikes in NOx than at lower concentrations. The amount of post-catalyst NOx produced during a step-transition is influenced by the engine controller and how quickly it adapts to the change in λ. Better tuned engine controllers respond more quickly and produce less NOx during H2 step-transitions. This research shows that some engines can violate NOx emissions limits with as little as a 5% increase in H2 due to slow engine controller response.Item Open Access Investigation into producer gas utilization in high performance natural gas engines(Colorado State University. Libraries, 2013) Wise, Daniel M., author; Olsen, Daniel B., advisor; Caille, Gary, committee member; Marchese, Anthony, committee member; Sharvelle, Sybil, committee memberA wide range of fuels are used in industrial gas fueled engines including well-head gas, pipeline natural gas, producer gas, coal gas, digester gas, landfill gas, and liquefied petroleum gas. Many industrial gas fueled engines operate both at high power density for increased efficiency and at ultra-lean air-fuel ratios for low NOx emissions. These two conditions require that engine operation occurs in a narrow air-fuel ratio band between the limits of misfire and the initiation of knock. The ability to characterize these limits for a given fuel is essential for efficient and effective engine operation. This work pursues two primary research objectives: (1) to characterize producer gas blends by developing prognostic tools with respect to a given blend's resistance to knock and (2) to develop a process to determine knock onset for a given fuel gas through direct indication from pressure transducer data at varied air-fuel ratios (ranging from stoichiometric to ultra-lean) as well as varied intake conditions (ranging from naturally aspirated to boosted intake pressures replicating turbocharged engines) and to quantitatively characterize the knock event using discreet and repeatable metrics derived from the analysis of the data. Methane number determination for natural gas blends is traditionally performed with research engines at stoichiometric conditions where the onset of knock is identified through subjective audible indication. To more closely replicate the operating conditions of a typical industrial engine, a Cooperative Fuel Research (CFR F2) engine is modified for boosted fuel/air intake and variable exhaust back pressure (to simulate turbocharger operation) with the incorporation of piezoelectric pressure transducers at the cylinder head to allow quantitative analysis of cylinder pressure conditions and transients precursive to, during, and following a knock event of varying magnitude. The interpretation of this data provides for evaluation of unique analytical methods to quantify and characterize engine knock under these conditions. In the course of this study an objective and consistent method for measuring methane number is developed, measured methane number for a total of 35 producer gas blends is provided, and a prognostic tool for predicting methane number, utilizing neural networks, is presented.Item Open Access Investigation of superturbocharger performance improvements through steady state engine simulation(Colorado State University. Libraries, 2010) Whitley, Kevin Lee, author; Olsen, Daniel B., advisor; Bradley, Thomas H., committee member; Zimmerle, Daniel John, committee member; Labadie, John W., committee memberAn integrated supercharger/turbocharger (SuperTurbo) is a device that combines the advantages of a supercharging, turbocharging and turbocompounding while eliminating some of their individual disadvantages. High boost, turbocompounding, and advanced controls are important strategies in meeting impending fuel economy requirements. High boost increases engine power output while many losses remain constant, producing an overall efficiency gain. Turbocompounding increases engine efficiency by capturing excess exhaust turbine power at high speed and torque. Supercharging increases low speed high torque operating performance. Steady state performance gains of a Superturbocharger equipped engine are investigated using engine simulation software. The engine simulation software uses a 1-D wave flow assumption to model the engine's unsteady flow behavior through one dimensional pipes. With these pipes connected to other engine components the overall performance of the engine can be modeled. GT-Power was chosen to run the simulations due to an already correlated engine model being available. This software is used to 'tune' an existing stock engine model to approximate stock engine data over the full speed and torque range. The SuperTurbo is added to the model and simulations are performed over the full engine speed and torque range for direct comparison with the stock engine. The model results show turbocompounding to be most effective at high speeds and torques in the area above 10 bar BMEP in the 3000 - 4000 RPM range and above 5 bar BMEP in the 500 - 6000 RPM range. In addition to turbocompounding there are fuel savings due to the reduced use of the compressor when it is not needed. With the stock configuration there is boost pressure created by compressor power that is then restricted by the throttle in the 2500 RPM range in the 8-12 bar BMEP range on up to 6000 RPM in the 2-10 bar BMEP range. The control of compressor speed to produce no boost at these locations improves efficiency by not wasting energy creating boost that is not needed.Item Open Access Large bore natural gas engine performance improvements and combustion stabilization through reformed natural gas precombustion chamber fueling(Colorado State University. Libraries, 2010) Ruter, Matthew D., author; Olsen, Daniel B., advisor; De Miranda, Michael A., committee member; Marchese, Anthony John, 1967-, committee memberLean combustion is a standard approach used to reduce NOx emissions in large bore natural gas engines. However, at lean operating points, combustion instabilities and misfires give rise to high total hydrocarbon (THC) and carbon monoxide (CO) emissions. To counteract this effect, pre-combustion chamber (PCC) technology is employed to allow engine operation at an overall lean equivalence ratio while mitigating the rise of THC and CO caused by combustion instability and partial and complete misfires. A PCC is a small chamber, typically 1-2% of the clearance volume. A separate fuel line supplies gaseous fuel to the PCC and a standard spark plug ignites the slightly rich mixture (1.1 < Φ < 1.2) in the PCC. The ignited PCC mixture enters the main combustion chamber as a high energy flame jet, igniting the lean mixture in the main chamber. Typically, natural gas fuels both the main cylinder and the PCC. In the current work reported herein, a mixture of reformed natural gas (syngas) and natural gas fuels the PCC. Syngas is a broad term that refers to a synthetic gaseous fuel. In this case, syngas specifically denotes a mixture of hydrogen, carbon monoxide, nitrogen, and methane generated in a natural gas reformer. Syngas has a faster flame speed and a wider equivalence ratio range of operation. Fueling the PCC with syngas reduces combustion instabilities and misfires. This extends the overall engine lean limit, enabling further NOx reductions. Research results presented are aimed at quantifying the benefits of syngas PCC fueling. A model is developed to predict the equivalence ratio in the PCC for different mixtures and flow rates of PCC fuel. An electronic injection valve is used to supply the PCC with syngas. The delivery pressure, injection timing, and flow rates are varied to optimize PCC equivalence ratio. The two syngas mixtures evaluated contain the same ratio of hydrogen to carbon monoxide but different levels of nitrogen diluent. The syngas with the higher nitrogen content is denoted syngas 1 while syngas 2 specifies the lower nitrogen content syngas. Experimental results are presented for 80% syngas / 20% natural gas mixtures for each syngas PCC fueling scenario at 18" Hg intake manifold pressure. 80% syngas 1 / 20% natural gas PCC fueling resulted in an 18% reduction in NOx emission compared to natural gas fueling. Supplying the PCC with 80% syngas 2 / 20% natural gas improves combustion stability by 16% compared to natural gas PCC fueling. Increasing the intake manifold pressure to 22" Hg for 80% syngas 2 / 20% natural gas fueling provides an emission comparison at an equivalent combustion stability operating point. Comparing equivalent combustion stability operating points between syngas 2 and natural gas shows a 40% reduction in NOx emissions when fueling the PCC with 80% syngas 2 / 20% natural gas mixture compared to natural gas fueling. Experimental results are presented for varying PCC fuel mixtures of syngas 2 and natural gas at 18" Hg intake manifold pressure. Results show dramatic increases in combustion stability are realized for high syngas 2 mixtures (greater than 80% syngas 2). Reducing intake manifold boost for natural gas PCC fueling to 8.5" Hg produces equivalent main cylinder combustion stability compared to 100% syngas 2 PCC fueling at 18" Hg intake manifold pressure. NOx emission increases by 780% for natural gas PCC fueling at the equivalent combustion stability operating point compared to syngas 2 PCC fueling at 18" Hg intake manifold pressure.Item Open Access Performance evaluation of multiple oxidation catalysts on a lean burn natural gas engine(Colorado State University. Libraries, 2012) Badrinarayanan, Koushik, author; Olsen, Daniel B., advisor; Marchese, Anthony, committee member; De Miranda, Michael A., committee memberEmission from lean burn natural gas engines used for power generation and gas compression are major contributors to air pollution. Two-way catalysts or oxidation catalysts are the common after-treatment systems used on lean burn natural gas engines to reduce CO, VOCs and formaldehyde emissions. The performance of the oxidation catalysts is dependent on operating parameters like catalyst temperature and space velocity. For this study, a part of the exhaust from a Waukesha VGF-18 GL lean burn natural gas engine was flowed through a catalyst slipstream system to access the performance of the oxidation catalysts. The slipstream is used to reduce the size of the catalysts and to allow precise control of temperature and space velocity. Analyzers used include Rosemount 5-gas emissions bench, Nicolet Fourier Transform Infra-Red spectrometer and HP 5890 Series II Gas Chromatograph. The oxidation catalysts were degreened at 1200°F (650°C) for 24 hours prior to performance testing. The conversion efficiencies for the emission species varied among the oxidation catalysts tested from different vendors. Therefore, the performance of all the oxidation catalysts is not the same for this application. Most oxidation catalysts showed over 90% maximum conversion efficiencies on CO, VOCs and formaldehyde. Saturated hydrocarbons such as propane were difficult to oxidize in an oxidation catalyst due to high activation energy. High VOC oxidation was noticed on all catalysts, with maximum conversion efficiency at 80%. VOC reduction efficiency was limited by propane emission in the exhaust for the catalyst temperatures tested. Additional formulations need to be developed for oxidation catalysts to increase VOC reduction efficiency. Oxidation of NO to NO2 was observed on most oxidation catalysts; this reaction is favored based on chemical equilibrium. Variation in space velocity showed very little effect on the conversion efficiencies. Most species showed over 90% conversion efficiency during the space velocity sweep. The oxidation catalysts showed increasing CH2O conversion efficiency with decreasing space velocity. No change on performance of the oxidation catalysts on conversion of emission species was noticed for varying space velocities after conversion efficiencies reached 90%. Thus, adding more catalyst volume may not increase the reduction efficiency of emission species. Varying cell density showed very little effect on performance of the oxidation catalysts. The friction factor correlation showed the friction factor is inversely proportional to cell density.Item Open Access Selective catalytic reduction: testing, numeric modeling, and control strategies(Colorado State University. Libraries, 2010) Schmitt, Joshua C., author; Olsen, Daniel B., advisor; Marchese, Anthony John, 1967-, committee member; Young, Peter M., committee memberSelective Catalytic Reduction (SCR) catalysts respond slowly to transient inputs, which is troublesome when designing ammonia feed controllers. An experimental SCR test apparatus was installed on a Cooper Bessemer GMV-4 natural gas engine. Transient data was taken of commercially available SCR Catalysts. These transient tests are used to quantify SCR catalyst response. Space velocity, catalyst temperature, inlet NOx concentration, and ammonia to NOx molar feed ratio were varied. A Simulink numeric model was created to examine the SCR transient phenomena. The Simulink numeric model showed in-catalyst ammonia and NOx concentration as a function of length in the direction of exhaust flow. This helped explain the SCR transient results. Transient testing showed a fifteen minute delayed response in NOx reduction from ammonia transitions. Ammonia slip succeeded ammonia transitions by thirty minutes. Simulink modeling revealed that these delays are caused by large quantities of ammonia stored in the catalyst. Due to ammonia storage, ammonia waves propagate through the catalyst, front to back. Emission of these constituents through the catalyst is delayed because the wave takes time to propagate through the entire catalyst length. Ammonia feed rate control testing was done on the experimental setup to improve ammonia and NOx emissions from the catalyst. Three control algorithms were used: feed forward control, using a pre ammonia injection ceramic NOx sensor; a feed forward plus feedback control, using a pre ammonia injection ceramic NOx sensor and post catalyst ceramic NOx sensor to generate feed signals; and a feed forward plus feedback algorithm that used a pre ammonia injection ceramic NOx sensor and a mid catalyst ceramic NOx sensor to generate feed forward and feedback signals. The feed forward controller used molar ratio as the control variable, and the feedback system used a technique that minimized the post catalyst ceramic NOx sensor signal. Ammonia to NOx molar ratio was stepped every five or fifteen minutes, and the algorithm made decisions, based on the catalyst response to the step. The decisions were made to minimize the post catalyst ceramic NOx sensor. Feed forward testing revealed that the lack of pressure compensation on ceramic NOx sensors causes errors in feed forward NOx readings, and sub optimal ammonia feed. Feedback testing revealed that a minimization technique can be used successfully with a feedback step rate of one step per fifteen minutes, and a step size of 5% ammonia to NOx molar ratio. The feedback algorithm, with the feedback ceramic NOx sensor located one third the way through the catalyst length, worked poorly. The technique approached a lean ammonia to NOx molar ratio, and stabilized slower than the post catalyst feedback ceramic NOx sensor technique. These phenomena are explained with the Simulink numeric model.Item Open Access Testing and performance measurement of straight vegetable oils as an alternative fuel for diesel engines(Colorado State University. Libraries, 2014) Lakshminarayanan, Arunachalam, author; Olsen, Daniel B., advisor; Marchese, Anthony, committee member; Byrne, Patrick, committee memberRising fuel prices, growing energy demand, concerns over domestic energy security and global warming from greenhouse gas emissions have triggered the global interest in bio-energy and bio-fuel crop development. Backlash from these concerns can result in supply shocks of traditional fossil fuels and create immense economic pressure. It is thus widely argued that bio-fuels would particularly benefit developing countries by off-setting their dependencies on imported petroleum. Domestically, the transportation sector accounts for almost 40% of liquid fuel consumption, while on-farm application like tractors and combines for agricultural purposes uses close to an additional 18%. It is estimated that 40% of the farm budget can be attributed to the fuel costs. With the cost of diesel continuously rising, farmers are now looking at using Straight Vegetable Oil (SVO) as an alternative fuel by producing their own fuel crops. This study evaluates conventional diesel compared to the use of SVO like Camelina, Canola and Juncea grown on local farms in Colorado for their performance and emissions on a John Deere 4045 Tier-II engine. Additionally, physical properties like density and viscosity, metal/mineral content, and cold flow properties like CFPP and CP of these oils were measured using ASTM standards and compared to diesel. It was found that SVOs did not show significant differences compared to diesel fuel with regards to engine emissions, but did show an increase in thermal efficiency. Therefore, this study supports the continued development of SVO production as a viable alternative to diesel fuels, particularly for on-farm applications. The need for providing and developing a sustainable, economic and environmental friendly fuel alternative has taken an aggressive push which will require a strong multidisciplinary education in the field of bio-energy. Commercial bio-energy development has the potential to not only alleviate the energy concerns, but also to give renewed impetus to the agricultural sector and rural development.Item Open Access Using prototypical sites to model methane emissions in Colorado’s Denver-Julesburg basin using mechanistic emissions estimation tool(Colorado State University. Libraries, 2023) Mollel, Winrose A., author; Olsen, Daniel B., advisor; Zimmerle, Dan, advisor; Baker, Dan, committee member; Quinn, Jason, committee memberThe BU methods estimate emissions by considering activity factors and emission factors averages for an extended period for a large area. Some TD methods use the ethane-methane ratio to attribute methane emissions from oil and gas facilities. The bottom-up (BU) inventory estimates are often used to drive the attribution of emissions indicated by TD data to different emission source categories. Despite widespread use, recent studies indicate that traditional bottom-up (BU) inventory methods do not adequately capture how variations in throughput and failure conditions impact gas composition and rate of emissions. Traditional BU methods typically do not model gas composition, although it differs among different facility configurations and impacts emissions from different equipment within one facility. Since most BU inventories utilize fixed emissions factors, emissions also do not scale due to throughput, which is particularly important for large emitters associated with failure conditions. Mechanistic emissions modeling can be used to address these shortcomings and make BU modeling more effective. This study illustrates how mechanistic modeling highlight changes in emissions due to variable throughput and equipment pressures and temperatures for the same production routed through the same or different production facility designs. The study uses the same mechanistic models to illustrate how the frequency of failure modes impacts both gas composition and total emissions. Results indicate mechanistic modeling could explain observed gas composition shifts in emitted emissions from production and midstream facilities over time, a key modeling input to improve voluntary and regulatory methane mitigation efforts.