Mountain Scholar :: Browsing by Author "Marchese, Anthony, committee member"

Browsing by Author "Marchese, Anthony, committee member"

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Open Access
A dynamic engineering model of algal cultivation systems
(Colorado State University. Libraries, 2017) Compton, Samuel Lighthall, author; Quinn, Jason C., advisor; Marchese, Anthony, committee member; Peers, Graham, committee member
Proper assessment of the sustainability of algal products is constrained by the onerous process of pilot-scale experimental study. This study developed a bulk growth model that utilizes strain characterization, geospatial data, and cultivation platform geometry to predict productivity across different outdoor systems. The model interprets a minimum of measureable algal strain characteristics along with characteristics of the growth architecture to calculate a time-resolved algal concentration. Validation of the model illustrates an average accuracy of 7.33%+/5.65% for photobioreactors (PBR) and 6.7%+/5.33% for an open raceway pond (ORP) across five total species: Chlorella vulgaris, Desmodesmus intermedius, Galdieria sulphuraria, Galdieria sulphuraria Soos, and Nannochloropsis oceanica. The validated model assesses productivity at several locations in the United States with Chlorella vulgaris, grown in open raceway ponds and Galdieria sulphuraria grown in vertical flat panel photobioreactors. The model investigates seasonal variability through geospatially and temporally resolved extrapolation.
Open Access
A fourth-order solution-adaptive finite-volume algorithm for compressible reacting flows on mapped domains
(Colorado State University. Libraries, 2019) Owen, Landon, author; Gao, Xinfeng, advisor; Guzik, Stephen, committee member; Marchese, Anthony, committee member; Estep, Donald, committee member
Accurate computational modeling of reacting flows is necessary to improve the design combustion efficiency and emission reduction in combustion devices, such as gas turbine engines. Combusting flows consists of a variety of phenomena including fluid mixing, chemical kinetics, turbulence-chemistry interacting dynamics, and heat and mass transfer. The scales associated with these range from atomic scales up to continuum scales at device level. Therefore, combusting flows are strongly nonlinear and require multiphysics and multiscale modeling. This research employs a fourth-order finite-volume method and leverages increasing gains in modern computing power to achieve high-fidelity modeling of flow characteristics and combustion dynamics. However, it is challenging to ensure that computational models are accurate, stable, and efficient due to the multiscale and multiphysics nature of combusting flows. Therefore, the goal of this research is to create a robust, high-order finite-volume algorithm on mapped domains with adaptive mesh refinement to solve compressible combustion problems in relatively complex geometries on parallel computing architecture. There are five main efforts in this research. The first effort is to extend the existing algorithm to solve the compressible Navier-Stokes equations on mapped domains by implementing the fourth-order accurate viscous discretization operators. The second effort is to incorporate the species transport equations and chemical kinetics into the solver to enable combustion modeling. The third effort is to ensure stability of the algorithm for combustion simulations over a wide range of speeds. The fourth effort is to ensure all new functionality utilizes the parallel adaptive mesh refinement infrastructure to achieve efficient computations on high-performance computers. The final goal is to utilize the algorithm to simulate a range of flow problems, including a multispecies flow with Mach reflection, multispecies mixing flow through a planar burner, and oblique detonation waves over a wedge. This research produces a verified and validated, fourth-order finite-volume algorithm for solving thermally perfect, compressible, chemically reacting flows on mapped domains that are adaptively refined and represent moderately complex geometries. In the future, the framework established in this research will be extended to model reactive flows in gas turbine combustors.
Open Access
A probabilistic and environmental impact assessment of a cyanobacteria-based biorefinery
(Colorado State University. Libraries, 2021) Beattie, Audrey, author; Quinn, Jason C., advisor; Arabi, Mazdak, committee member; Marchese, Anthony, committee member
Microbial based biofuels represent a potential promising solution as an environmentally favorable transportation fuel. Cyanobacteria have many of the same advantages as microalgae: ability for rapid growth in otherwise non-arable regions, suitability for genetic engineering, and simple nutritional needs. Additionally, cyanobacteria can be engineered to secrete valuable co-products that can be harvested independent from the produced biomass. However, little work has been done to identify the processes and the economic and environmental impacts associated with a large-scale cyanobacteria-to-fuels facility. The present study is a concurrent techno-economic and life cycle assessment of a facility that generates fuels and methyl laurate, an oleochemical, from the cyanobacterial species Synechocystis sp. PCC 6803. The biorefinery model includes all aspects of cultivation, separation of the secreted methyl laurate, biomass harvesting and fuel processing via hydrothermal liquefaction (HTL) of the dewatered biomass. The assessments leverage Monte Carlo analysis (MCA) to address uncertainty and variability inherent in the most significant input parameters, replacing them with probabilistic functions. For the facility configuration producing both fuels and the oleochemical co-product, the MCA average minimum fuel selling price (MFSP) is $2.47 per liter or $9.34 per gallon of gasoline equivalent (gge) with the corresponding average global warming potential determined to be 118 g CO2-eq/MJ-1. The case producing only fuels results in an MCA average MFSP of $2.01/L-1 ($7.60/gge) and an average environmental impact of 100 g CO2-eq/MJ-1. These results are compared to static optimistic and conservative scenario analysis estimates, illustrating the over- and under-estimation of outcomes associated with non-stochastic methods. Suggested facility improvements include increases in pond productivity of both the biomass and methyl laurate oil production, as well as improvements to carbon utilization and bio-crude yield from HTL processing.
Open Access
Advanced control techniques and sensors for gas engines with NSCR
(Colorado State University. Libraries, 2012) Gattoni, John, author; Olsen, Daniel, advisor; Marchese, Anthony, committee member; Young, Peter, committee member
High exhaust emissions reduction efficiency from an Internal Combustion Engine (ICE) utilizing a Non Selective Catalyst Reduction (NSCR) catalyst system requires complex fuel control strategies. The allowable equivalence ratio operating range is very narrow where NSCR systems achieve simultaneous reduction of Carbon Monoxide (CO), Nitrogen Oxides (NOx), Total Hydrocarbons (THC), Volatile Organic Compounds (VOC's), and formaldehyde (CH2O). This range is difficult to maintain as transients are introduced into the system. Current fuel control technologies utilizing lambda sensor feedback are reported to be unable to sustain these demands for extended operation periods. Lambda sensor accuracy is the critical issue with current fuel controllers. The goal of this project was to develop a minimization control algorithm utilizing a Continental NOx sensor installed downstream of the NSCR catalyst system for feedback air/fuel ratio control. When the engine is operated under lean conditions, NOx is produced in the engine out exhaust emissions and the NOx sensor responds accordingly. When the engine is operated under rich burn conditions, the NSCR catalyst system produces Ammonia (NH3). NOx sensors have a cross sensitivity to NH3 and will respond as though it has been exposed to NOx. This behavior provides a unique control strategy that allows lambda sensor calibration to be ignored. Testing was performed on a Cummins-Onan Generator Set, model GGHD 60HZ, capable of a power output of 100kW at standard ambient air conditions. The engine was reconfigured to operate utilizing an electronic gas carburetor (EGC2) with lambda sensor feedback, manufactured by Continental Controls Corporation (CCC) and a high reduction efficiency NSCR catalyst system manufactured by DCL International. A Data Acquisition (DAQ) system manufactured by National Instruments (NI) acquired the NOx sensor output. The control algorithm was programmed utilizing a LabVIEW interface and a feed forward command was executed through the NI DAQ system to the CCC EGC2 where the fuel trim adjustment was physically made. Exhaust gas species measurements were acquired via a Rosemount 5-gas analyzer and a Nicolet 6700 FTIR. Fuel composition was acquired utilizing a Varian CP-4900 Micro GC and Air Fuel Ratio (AFR) was obtained with an ECM AFRecorder 4800R. Results utilizing NOx sensor feedback control revealed that under steady state operating conditions, improvements in emissions reduction efficiency of CO, NOx, and THC were significant. The system was also evaluated during load and fuel composition transients.
Open Access
Algae-to-fuel pathways: integration of cultivation studies, process modeling, techno-economic analyses, and life cycle assessments
(Colorado State University. Libraries, 2022) Chen, Peter H., author; Quinn, Jason C., advisor; Bradley, Thomas, committee member; Marchese, Anthony, committee member; Reardon, Kenneth, committee member
Researchers have recognized the potential of microalgae for renewable fuels for several decades, with a sharp increase in interest in the past decade. Though progress in algal cultivation and conversion has been substantial, commercialization of algal fuels has not yet been achieved. Economic metrics must be balanced with renewable fuel goals such that algal fuels can be competitive with conventional petroleum fuels. Through process modeling, techno-economic analysis (TEA), and life cycle assessment (LCA), the work in this dissertation seeks to illuminate improvements to algal fuel systems and outline the steps required to advance algal fuels toward commercialization. This work heavily focuses on hydrothermal liquefaction (HTL), a thermochemical process that converts whole wet biomass into biocrude, a petroleum crude oil analog. An aqueous phase, a gaseous phase, and a solid phase are created alongside the primary biocrude product. The aqueous phase of HTL notably contains a high content of nitrogen, which could potentially be recycled back to algae cultivation. At a scale where algal biofuels would meet a significant portion of transportation fuel needs, the demand for nutrients, specifically nitrogen and phosphorus, would exceed current global agricultural production. While recycling the aqueous phase could alleviate the demand for fresh nutrients in algae cultivation, it also contains toxic components, which include heterocyclic nitrogen compounds and phenolic compounds. The first phase of this research is an experimental component that focuses on methods for improving the recyclability of nutrients in the aqueous phase. A novel use of adsorbents (activated carbon and ion-exchange resins) was discovered for reducing the presence of components that are toxic to algae growth. The second research phase is a comprehensive modeling effort of the HTL process. A process model was developed in Aspen Plus from a robust assessment of current literature. These results are fed into TEA and LCA models to fully demonstrate the effects that process uncertainties have on the viability of HTL. For example, the high-temperature conditions that define HTL require the material to maintain a subcritical liquid state, which complicates the assessment of accurate thermochemical properties due to the required pressure. To clarify this issue, the work in this research phase compares the estimated performance of algal HTL between different thermodynamic models. HTL environmental metrics beyond global warming potential and net energy ratio are also discussed for the first time. Uncertainties in conversion performance are bounded through a scenario analysis that manipulates parameters such as product yield and nutrient recycle (as discussed in the first research phase) to establish a range of economic results and environmental impacts. The work is supplemented with a publicly available model to support future hydrothermal liquefaction assessments and accelerate the development of commercial-scale systems. The third and final research phase compares HTL with a fractionation train called Combined Algal Processing (CAP) and takes into consideration the possibility of integrating HTL downstream of CAP. CAP can be described as a pretreatment and fermentation step followed by a lipid extraction step to extract carbohydrates and lipids, respectively, for fuel products. However, CAP cannot convert proteins to fuels, making the process highly dependent on feed composition from the cultivation stage. HTL's advantage over CAP is its relative agnosticism to composition, but it requires greater capital costs and is more energetically intensive. A fuzzy logic approach is proposed to compare CAP and HTL process models through relevant performance metrics and to map algal feed conditions that lead to optimal algae-to-fuel pathways. Thresholds are set for fuzzy membership functions in relevant performance objectives: minimum fuel selling price (MFSP), global warming potential (GWP), and net energy ratio (NER). The membership functions yield "satisfaction scores" for each objective and factor into an overall satisfaction score. Individual and overall satisfaction scores for each pathway are mapped to the full range of feed compositions (proteins, carbohydrates, and lipids). A composition-based algal growth model was then implemented to perform an uncertainty analysis through Monte Carlo simulations. The impact on satisfaction scores from varying other key process model parameters, such as algae productivity, individual process yields, process operating parameters, and life cycle inventory uncertainty are highlighted in these select scenarios.
Open Access
Analysis of life cycle assessment of food/energy/waste systems and development and analysis of microalgae cultivation/wastewater treatment inclusive system
(Colorado State University. Libraries, 2013) Armstrong, Kristina Ochsner, author; Bradley, Thomas H., advisor; De Long, Susan, committee member; Marchese, Anthony, committee member
Across the world, crises in food, energy, land and water resources, as well as waste and greenhouse gas accumulation are inspiring research into the interactions among these environmental pressures. In the food/energy/waste problem set, most of the research is focused on describing the antagonistic relationships between food, energy and waste; these relationships are often analyzed with life cycle assessment (LCA). These analyses often include reporting of metrics of environmental performance with few functional units, often focusing on energy use, productivity and environmental impact while neglecting water use, food nutrition and safety. Additionally, they are often attributional studies with small scope which report location-specific parameters only. This thesis puts forth a series of recommendations to amend the current practice of LCA to combat these limitations and then utilizes these suggestions to analyze a synergistic food/waste/energy system. As an example analysis, this thesis describes the effect of combining wastewater treatment and microalgae cultivation on the productivity and scalability of the synergistic system. To ameliorate the high nutrient and water demands of microalgae cultivation, many studies suggest that microalgae be cultivated in wastewater so as to achieve large scale and low environmental costs. While cultivation studies have found this to be true, none explore the viability of the substitution in terms of productivity and scale-up. The results of this study suggest that while the integrated system may be suitable for low-intensity microalgae cultivation, for freshwater microalgae species or wastewater treatment it is not suitable for high intensity salt water microalgae cultivation. This study shows that the integration could result in reduced lipid content, high wastewater requirements, no greenhouse gas emissions benefit and only a small energy benefit.
Open Access
Application of alcohols in spark ignition engines
(Colorado State University. Libraries, 2018) Aghahossein Shirazi, Saeid, author; Reardon, Kenneth, advisor; Foust, Thomas, committee member; Dandy, David, committee member; Marchese, Anthony, committee member; Windom, Bret, committee member
Replacing petroleum fuels with sustainable biofuels is a viable option for mitigation of climate change. Alcohols are the most common biofuels worldwide and can be produced biologically from sugary, starchy and lignocellulosic biomass feedstocks. Alcohols are particularly attractive options as fuels for spark ignition engines due to the high octane values of these molecules and their positive influence on performance and emissions. In the context of the US Department of Energy's Co-Optimization of Fuels and Engines (Co-Optima) initiative, a systematic product design methodology was developed to identify alcohols that might be suitable for blending with gasoline for use in spark ignition engines. A detailed database of 943 molecules was established including all possible molecular structures of saturated linear, branched, and cyclic alcohols (C1-C10) with one hydroxyl group. An initial decision framework for removing problematic compounds was devised and applied. Next, the database and decision framework were used to evaluate alcohols suitable for blending in gasoline for spark ignition engines. Three scenarios were considered: (a) low-range (less than 15 vol%) blends with minimal constraints; (b) ideal low-range blends; and (c) high-range (greater than 40 vol%) blends. A dual-alcohol blending approach has been tested. In addition, the azeotropic volatility behavior and mixing/sooting potential of the single and dual-alcohol gasoline blends were studied by monitoring the distillation composition evolution and coupling this with results of a droplet evaporation model. Although nearly all of the work done on alcohol-gasoline blends has been on single-alcohol blends, the results of this study suggest that dual-alcohol blends can overcome many of the limitations of single-alcohol blends to provide a broader spectrum of advantaged properties. A third study focused on the possibility of replacing anhydrous ethanol fuel with hydrous ethanol at the azeotrope composition, which can result in significant energy and cost savings during production. In this collaborative study, the thermophysical properties and evaporation dynamics of a range of hydrous and anhydrous ethanol blends with gasoline were characterized. The results showed that hydrous ethanol blends have the potential to be used in current internal combustion engines as a drop-in fuel with few or no modifications.
Open Access
Bioplastic production from microalgae with fuel co-products: a techno-economic and life-cycle assessment
(Colorado State University. Libraries, 2019) Beckstrom, Braden Dale, author; Quinn, Jason C., advisor; Marchese, Anthony, committee member; Sheehan, John, committee member
Concerns over depleting oil reserves and national security have spurred renewed vigor in developing bio-based products. One specific area of growing concern is the consumption of petroleum based plastics, which is expected to consume 20% of global annual oil by 2050. Algae systems represent a promising pathway for the development of a bioplastic feedstock but have many technological challenges. Algae-based plastics offer a promising alleviate that would decrease oil consumption, improve environmental impact, and in some cases even improve plastic performance. This study investigates the economic viability and environmental impact of an algae biorefinery that integrates the complementary functions of bioplastic and fuel production. The bioplastic and biofuel biorefinery modeled herein includes nine different production scenarios. Performance of the facility was validated based on experimental systems with modeling work focusing on mass and energy balances of all required sub-processes in the production pathway. Results show the minimum selling price of the bioplastic feedstock is within the realm of economic competition with prices as low as $970 USD tonne-1. Additionally, LCA results indicate drastic improvements in environmental performance of the produced bioplastic feedstock, with reductions ranging between 67-116% compared to petroleum based plastics. These results indicate that an algae biorefinery focused on bioplastic feedstock production and fuels has the potential to operate both economically and sustainably. Sensitivity analysis results, alternative co-products (given that fuels represent minimal value) and product market potential are discussed.
Open Access
Catalytic biomass conversion and upgrading into platform chemicals and liquid fuels
(Colorado State University. Libraries, 2014) Liu, Dajiang, author; James, Susan, advisor; Chen, Eugene, advisor; Williams, John, committee member; Marchese, Anthony, committee member; Fisk, Nick, committee member
The development of novel, efficient catalytic processes for plant biomass conversion and upgrading into versatile platform chemicals as well as oxygenated biodiesel and premium hydrocarbon kerosene/jet fuels is described in this dissertation. The chief motivation of using annually renewable biomass as the source of chemical building blocks and transportation fuels is to reduce societal dependence on depleting fossil fuels. Towards this goal, 5-hydroxymethylfurfural (HMF), the dehydration product from C6 (poly)sugars, has been intensively investigated as it has been identified as a versatile C6 intermediate or platform for value-added chemicals and biofuels. This work has developed several highly efficient and cost-effective catalyst systems for C6 (poly)sugars conversion to HMF under mild conditions, including ubiquitous and inexpensive aluminum alkyl or alkoxy compounds, recyclable polymeric ionic liquid (PIL)-supported metal (Cr, Al) catalysts, and thiazolium chloride, a recyclable Vitamine B1 analog. An integrated, semi-continuous process for the HMF production from fructose has also been developed, affording the high-purity HMF as needle crystals. Towards HMF upgrading into higher-energy-density fuel intermediates, developing new strategies of C-C bond formation or chain extension is of particular interest. In this context, this study has discovered that N-heterocyclic carbenes (NHCs) are highly effective organic catalysts for HMF self-condensation to 5,5'-dihydroxymethylfuroin (DHMF), a new C12 biorefining building block. This new upgrading process has 100% atom economy, can be carried out under solvent-free conditions, and produces the C12 DHMF with quantitative selectivity and yield, the hallmarks of a "green" process. More significantly, the C12 DHMF has been transformed catalytically into oxygenated biodiesels, high-quality alkane jet fuels, and sustainable polymers, thereby establishing DHMF as a new C12 biomass platform chemical.
Open Access
Control of an 8L45 transmission inside the Colorado State University EcoCAR 3 2016 Chevrolet Camaro
(Colorado State University. Libraries, 2021) Knackstedt, Clinton, author; Quinn, Jason, advisor; Bradley, Thomas, committee member; Marchese, Anthony, committee member
The hybridization and electrification of vehicles brings new challenges to the engineering and development of automotive control systems. Parallel, single motor pre-transmission hybrid electric vehicles are a preferred design for hybrid vehicles because of the mechanical simplicity, in that the electric motor and engine are on a common axis, connected to the transmission. Mechanically, this configuration enables the electric motor to take advantage of the torque multiplication of the final drive gear and transmission. From a controls perspective, this configuration is complicated because the engine, motor and transmission must work together to achieve the system-level objectives of fuel economy and driveability. These challenges are exemplified in the development of the hybrid 2016 Chevy Camaro developed by the Colorado State University (CSU) EcoCAR 3 team. The results of this thesis demonstrate model development, model validation, and controls development to control the operation of the electric motor and engine together for driveability and performance during transmission gear changes. A model was developed in MATLAB Simulink to predict the behavior and performance of the 8-speed automatic transmission 8L45 that is stock to the 2016 Chevrolet Camaro. The performance of this model was validated by comparison to on-track vehicle data with <0.3m/s average error in prediction of the vehicle speed trace. A control system was developed to enable control of electric motor torque during shifts which eliminates ignition timing-based torque requests while maintaining driveability-derived shift dynamics. This work has implications for the design of automatic transmission hybrid electric vehicles with discussion focusing on the potential for integration of learning technologies and minimization of gear lash.
Open Access
Deactivation of ZSM-5 during catalytic fast pyrolysis of biomass
(Colorado State University. Libraries, 2018) Stanton, Alexander R., author; Reardon, Kenneth, advisor; Iisa, Kristiina, advisor; Dandy, David, committee member; Marchese, Anthony, committee member; Smith, Gordon, committee member
To view the abstract, please see the full text of the document.
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 member
Rich 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.
Open Access
Development and testing of a solid core fiber optic delivery system and ultraviolet preionization for laser ignition
(Colorado State University. Libraries, 2012) Wilvert, Hurley Nicholas, author; Yalin, Azer, advisor; Marchese, Anthony, committee member; Rocca, Jorge, committee member
Laser ignition of natural gas engines has shown potential to improve many facets of engine performance including brake thermal efficiency, exhaust emissions, and durability as compared with traditional spark ignition. Laser ignition technology has yet to transition to industry primarily because no system for reliably and safely delivering the laser pulse to the combustion chamber exists. This thesis presents a novel fiber optic delivery approach using solid core multimode step index silica fibers with large cladding diameters (400 μm core, 720 μm cladding). Testing was done on the fibers to determine their response to bending, vibration, high power input, and long duration beam transmission. It was found that in configurations representative of what is required on a real engine, and in the presence of vibration, reliable spark formation could be achieved in pressures as low as 3.4 bar using a specially designed optical spark plug. Comparative tests between the fiber delivered laser ignition system and a traditional J-gap spark plug were performed on a single cylinder Waukesha Cooperative Fuel Research (CFR) engine running on bottled methane. Tests were run at three different Net Mean Effective Pressures (NMEP) of 6, 8, and 12 bar at various air-fuel ratios. Results indicate reliable performance of the fiber and improved engine performance at high NMEP and lean conditions. Thesis research also includes initial studies into the use of dual laser pulses for plasma formation and ignition. In this approach, a first ultraviolet pulse preionizes a volume of air while a second overlapped pulse adds additional energy. Electron density measurements reveal the ultraviolet beam generates substantial preionization even with no visual breakdown, and Schlieren images are used to study the interaction between the two beams at atmospheric and lower pressures.
Open Access
Development of mobile open-path cavity ring-down spectrometer for measurement of trace atmospheric methane gas
(Colorado State University. Libraries, 2018) McHale, Laura, author; Yalin, Azer P., advisor; Marchese, Anthony, committee member; Olsen, Daniel, committee member; Pierce, Jeffrey, committee member
Use in recent decades of methane as a 'clean' alternative to coal and gasoline has seen a rapid increase in natural gas extraction in the United States. Although combustion of methane produces less CO2 than traditional fuels, it is a powerful greenhouse gas with a 20 year Global Warming Potential (GWP20) that is 84x that reported for CO2 in the latest IPCC report; therefore, the promise of natural gas as a clean fuel can only by realized if emissions of uncombusted gas are sufficiently low. To address this problem, there is a need for both regional (basin wide) measurements of methane emissions to determine global levels, as well as localized measurements to allow identification and reduction of emissions ("leaks") from specific equipment. The goal of this research is to develop a mobile open-path cavity ring-down spectroscopy (CRDS) sensor for localized measurements of atmospheric methane. While designed with the oil and gas industry in mind, the technology also has application to study emissions from agricultural operations and those from other sectors. This thesis presents development from proof-of-concept open-path sensor through two mobile iterations. CRDS can provide fast, non-intrusive, sensitive measurements; but in contrast to available instruments, the focus is on open-path operation (no flow-cell and pump) to provide opportunities for significant weight, size and power reductions to increase the mobility of the technique (<4 kg, <25 W). Challenges of open-path operation, such as fitting broadened spectral peaks, preserving mirror cleanliness and techniques for removing signal noise due to aerosol particles are addressed. The sensor is based on widely available and mature engineering near-infrared (NIR) opto-electronic components that have been developed for the telecom industry. Sensor validation with known methane concentrations show that the open-path sensor is capable of measuring atmospheric concentrations in the range of ~1.8-20+ ppmv at a rate of 1-3 Hz. Sensitivity studies using Allan variance techniques show sensitivity of < 20 ppbv in 1 – adequate for practical leak detection of small plumes <1 ppmv. Comparisons against a commercially available closed path sensor in mobile deployments are presented, along with mobile measurements from natural gas facilities in Platteville, CO and Washington County, PA. Finally, integration of the sensor onto a UAS platform for airborne measurements of methane and ammonia from agricultural applications is discussed.
Open Access
Effect of phase change material on dynamic thermal management performance for power electronics packages
(Colorado State University. Libraries, 2021) Hollis, Justin Ralph, author; Bandhauer, Todd M., advisor; Marchese, Anthony, committee member; Young, Peter, committee member
High temperature silicon carbide (SiC) die are the most critical and expensive component in electric vehicle (EV) power electronic packages and require both active and passive methods to dissipate heat during transient operation. The use of phase change materials (PCMs) to control the peak junction temperature of the SiC die and to buffer the temperature fluctuations in the package during simulated operation is modeled here. The latent heat storage potential of multiple PCM and PCM composites are explored in both single-sided and dual-sided package configurations. The results of this study show that the addition of phase change material (PCM) into two different styles of power electronics (PE) packages is an effective method for controlling the transient junction temperatures experienced during two different drive cycles. The addition of PCM in a single-sided package also serves to decrease temperature fluctuations experienced by the package as a whole and may be used to reduce the necessary number of SiC die required to divide the heat load, lowering the overall material cost and volume of the package by over 50%. PCM in a single-sided package may be nearly as effective as the double-sided cooling approach of a dual-sided package in the reduction of both peak junction temperature of SiC as well as controlling temperature variations between package layers.
Open Access
Evaluation of a non-thermal plasma generator for plasma-assisted combustion in an oil burner
(Colorado State University. Libraries, 2013) Doyle, Jake Downin, author; Yalin, Azer, advisor; Joshi, Sachin, advisor; Marchese, Anthony, committee member; Collins, George, committee member
The addition of plasma to a combustion system has the potential to increase the combustion efficiency and reduce harmful emissions by reforming hydrocarbon fuels. The ability for plasma to reform fuel to create hydrogen-rich synthesis gas has been shown by other researchers. The work presented in this thesis includes the characterization of a plasma generator patented by Clean Diesel, LLC and testing an oil burner that was modified to use the plasma generator for combustion enhancement. The plasma was generated by six electrodes with a circulating high voltage pulse created by a signal generator and high voltage transformers. The plasma is characterized through optical emission spectroscopy and with electrical measurements, where it was shown to be a non-thermal plasma operating in the glow-to-arc transition region. The plasma generator was then implemented into an oil burner where its thermal efficiency and emissions were compared to that of a stock Riello F10 burner. Testing showed similar efficiencies for the modified and stock burners (contrary to previous testing that showed improvements due to plasma assistance). Carbon monoxide and nitrogen oxides were considered as the key pollutants, and it was shown that NOx emissions exceeded that of the stock burner, although CO levels were reduced. Further testing was performed with additional modifications such as fuel spray type, electrode insulation, and plasma frequency, although none showed significant improvements in its operation. The results have led to the realization that a more volumetric plasma that can provide longer residence time for fuel interaction is likely needed for effective fuel reforming.
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 member
Engine 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.
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 member
Amongst 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.
Open Access
Geographical assessment of algal productivity and water intensity across the United States
(Colorado State University. Libraries, 2021) Quiroz, David, author; Quinn, Jason C., advisor; Marchese, Anthony, committee member; Reardon, Kenneth, committee member
Water consumption due to evaporation in open algal cultivation systems represents a significant research gap in the resource assessment literature. Existing algal evaporation models often lack high spatiotemporal resolution or are not validated with experimental systems. This study presents a geographical and temporal assessment of the water requirements for commercial-scale production of algae biomass through a dynamic integrated thermal and biological modeling framework. Water demands were calculated through a validated dynamic thermal model which predicts temperature with an accuracy of -0.96 ± 2.72 °C and evaporation losses with a 1.46 ± 5.92 % annual accuracy. The biological model was validated with experimental data representing the current state of technology and shows an average error of -4.59 ± 8.13 %. The integrated thermal growth model was then utilized to simulate the water demands for biomass production of a 400-hectare algae farm at 198 different locations across the United States over a period of 21 years. Simulation outputs were used to determine algal protein yields, based on protein content, and fuel production via hydrothermal liquefaction. This foundation is integrated with life cycle methodology to determine the water footprint of algal biomass, proteins, and biofuels and to compare them to those of traditional energy crops and conventional fuels. Results indicate that less water-intensive cultivation can be achieved in the Gulf Coast region, where the average water footprints of the three simulated pathways were determined to be 155 m3 water tonne-1 biomass, 371 m3 water tonne-1 algal proteins, and 11 m3 GJ-1 biofuel. The water footprints of algal systems were found to be more favorable when compared to traditional biomass feedstocks such as soybeans and corn. However, when compared to petroleum-based fuels, results emphasize the need for more water-efficient strategies to reduce the water demands of algal cultivation. This work also incorporates a novel temperature tolerance assessment to identify the geographically specific temperature limits for algal strains in a commercial-scale facility. Results highlight the importance of high temporal and spatial resolution when modeling culture temperature, evaporative loss, and algae growth rate.
Open Access
Impacts of oil and natural gas development and other sources on volatile organic compound concentrations in Broomfield, Colorado
(Colorado State University. Libraries, 2022) Lachenmayer, Emily, author; Collett, Jeffrey, advisor; Fischer, Emily, committee member; Marchese, Anthony, committee member
In 2017 substantial new oil and natural gas (ONG) extraction was approved by the City and County of Broomfield (CCOB). A monitoring program was established by CCOB to determine how new ONG extraction impacted local air quality. Multiple instruments were utilized to monitor air quality in the county including weekly volatile organic carbon (VOC) sampling canisters deployed across CCOB by Colorado State University and Ajax Analytics and hourly VOC, methane, and criteria pollutant measurements taken by the Colorado Air Monitoring Mobile Lab (CAMML) deployed near an ONG well-pad by the Colorado Department of Public Health and Environment (CDPHE). Weekly samples, collected from October 2018 through December 2020 were analyzed for 52 VOCs using a 5-channel gas chromatograph. The CAMML reported 20 VOCs, methane, PM2.5, PM10, nitrogen oxides (NOx), and ozone. Positive Matrix Factorization (PMF) was applied to both datasets to characterize key air pollution sources and their impacts in space and time. Six factors were found to describe the weekly data best: Background (biogenic), Combustion, Light Alkane, Complex Alkane, a Drilling factor, and an Ethyne factor. Contributions of the ONG-related PMF factors increased most strongly near well-pads during particular ONG pre-production activities. The Light Alkane factor was most active during production and coiled tubing operations, and flowback at one or more of the new well-pads. The Complex Alkane factor iii was strongly associated with drilling and coiled tubing operations and flowback at one of two well-pads. The Drilling factor contained a VOC profile that closely matched volatiles released from a drilling mud (lubricant for the drill bit) used at two of the three sites. The Ethyne profile represents an unknown and previously undocumented source composition originating from a well-pad. This ethyne and benzene-rich emission was independently observed in other CCOB air monitoring efforts. Five factors best explained the hourly CAMML data; these factors resembled those derived from PMF analysis of the weekly data set. Three factors, Combustion, Ozone background, and Particulate Matter, were not found to be related to local ONG extraction while the profiles containing many of the alkane species (Light Alkane factor and Complex Alkane factor) showed correlation with pad activities. Wind direction analysis suggests emissions associated with these factors were transported from the pad. Benzene was a particular focus of the study given its potential health effects at modest concentration levels. On average, the source factors contributing most to benzene were combustion (38%), longer-lived alkanes from ONG production (22%), and shorter-lived alkanes from ONG production (16%). ONG activities contributed more strongly to benzene levels during pre-production and production phases.