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Browsing by Author "Windom, Bret C., advisor"

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    Characterization of direct injected propane and iso-octane at engine-like conditions in a high-pressure spray chamber
    (Colorado State University. Libraries, 2022) Windell, Brye Thomas, author; Windom, Bret C., advisor; Olsen, Daniel, committee member; Venayagamoorthy, Subhas Karan, committee member
    This thesis focuses on the recommission, modification, and testing of a high-pressure spray chamber (HPSC) and its role in aiding the experimental and numerical examination of direct injection (DI) propane at various engine-like conditions to address fundamental limitations of achieving near diesel efficiencies in heavy duty on-road liquified petroleum gas (LPG) engines. The HPSC was reconstructed and is capable of incorporating optical diagnostic techniques including high-speed Schlieren and planar Mie scattering imaging. High-speed Schlieren was used to characterize the global spray morphology and vapor phase regions while planar Mie scattering allowed for individual plume resolution providing insights into the liquid regions of the spray. These optical imaging techniques unveiled propane's spray propagation was fed by flash boiling effects, spray collapse, and high degree of vaporization, unlike iso-octane. This resulted in a direct proportionality of propane's penetration length to temperature, an inversely proportional relationship to ambient pressure, and a direct proportionality to injection pressure. Contrary to propane, iso-octane's spray morphology exhibited minor changes as temperatures and pressures were varied. Due to these unique effects, flash boiling, spray collapse, and high degree of vaporization, propane is classified as an unconventional spray, dissimilar to iso-octane's spray morphology. Experimental testing provided corrections to numerical models that were developed to reproduce the under-expanded jet dynamics. The numerical modeling results were found to be sensitive to cone and inclusion angles. The current work serves as preliminary results for an experimental validation campaign which aid in the numerical model development for future heavy duty on-road LPG engines.
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    Computer aided engineering of an automobile gasoline refueling system
    (Colorado State University. Libraries, 2018) Dake, Mangesh, author; Windom, Bret C., advisor; Marchese, Anthony J., committee member; Venayagamoorthy, Karan S., committee member
    A vehicle's refueling system, including components which make up the Onboard Refueling Vapor Recovery (ORVR) system, must be designed to meet federally set evaporative hydrocarbon emission regulations and other performance issues inherent to the refueling process, such as premature click-off of the refueling nozzle and spit-back. A Computational Fluid Dynamics (CFD) model able to predict the performance of a vehicle's refueling system could be a valuable tool towards the development of future gasoline refueling system designs, saving the Original Equipment Manufacturer's time and money currently invested in the research and development of these systems. To create an adequate model required for Computer Aided Engineering (CAE) of a modern refueling system, it is paramount to accurately predict the fluid dynamics through and out of a gasoline refueling nozzle, within the different components inside the refueling system, and the outlets of the fuel tank. Using CFD, this study aims to predict the performance of a refueling system. The commercial CFD software, Star-CCM+, was used to model fuel flow through a currently in production refueling system geometry. Experiments were conducted using a test setup to mimic the simulated refueling system to carefully describe the system's boundary and initial conditions and to evaluate the CFD results. It was found that modeling of the fluid dynamics through the air entrainment and pressure port geometries within the refueling nozzle were needed to accurately capture fuel spray behavior as demonstrated by experiments. By monitoring the amount of liquid fuel contacting the pressure port on the refueling nozzle, the simulations are able to identify fillerpipe designs that fail as a result of early click-off. Simulations of the complete refueling system, while neglecting phase change of the fuel, were able to predict the trends and dynamics of the tank pressure experienced by the experiments for varying fuel pump flow rates. The study acts as a guide for future refueling simulations involving fuel evaporation, for which initial results are presented.
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    Effect of endothermic reactions on the global extinction strain rate of large hydrocarbon fuels
    (Colorado State University. Libraries, 2018) Jadhav, Anish, author; Windom, Bret C., advisor; Bandhauer, Todd, committee member; Hussam, Mahmoud, committee member
    When a hydrocarbon fuel is used as a coolant, the extreme environment can have a significant impact on the fuel composition. Heat exchange occurs through phase change, sensible heat extraction, and endothermic reactions experienced by the liquid fuel. From previous studies it has been demonstrated that the fuel composition changes significantly as well as the fuel properties as a result of the endothermic reactions. To investigate the effect of endothermic reactions on the fundamental flame behavior we have developed a counterflow flame burner that can measure the flame extinction strain rate of a thermally stressed fuel. The counterflow flame burner is coupled with a high-pressure reactor, capable of exposing the fuel to extreme conditions of 170 atm and 650 °C. Flame robustness is quantified by measuring the flame extinction strain rate. n-heptane is studied as a first attempt to understand the role of the endothermic reactions on the combustion and flame behavior of a liquid rocket propellant fuel. Modeling of the reactor and the counterflow flame is carried out using CHEMKIN. The flame extinction strain rate of the reacted n-heptane is compared with the unreacted n-heptane flame, thus allowing us to determine and extrapolate the role of endothermic reactions on the combustion behavior of jet and rocket fuels.
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    Experimental investigation of automotive refueling system flow and emissions dynamics to support CFD development
    (Colorado State University. Libraries, 2019) Stoker, T. McKay, author; Windom, Bret C., advisor; Jathar, Shantanu, committee member; Carter, Ellison, committee member
    Government regulations restrict the evaporative emissions during refueling to 0.20 grams per gallon of dispensed fuel. This requires virtually all of the vapors generated and displaced while refueling to be stored onboard the vehicle. The refueling phenomenon of spit-back and early click-off are also important considerations in designing refueling systems. Spit-back is fuel bursting past the nozzle and into the environment and early click-off is the pump shutoff mechanism being triggered before the tank is full. Both are detrimental to customer satisfaction, and spit-back leads to failing government regulations. Development of a new refueling system design is required for each vehicle as packaging requirements change. Each new design (or redesign) must be prototyped and tested to ensure government regulations and customer satisfaction criteria are satisfied. Often designs need multiple iterations, costing money and time in prototype-based validation procedures. To conserve resources, it is desired to create a Computational Fluid Dynamics (CFD) tool to assist in design validation. To aid in creating such a model, controlled experiments were performed to inform and validate simulations. The simulations and experiments were performed on the same in-production refueling system. Test data provided characterization of non-trivial boundary conditions. Refueling experiments gave points of comparison for CFD results, especially the tank pressure. Finally, collection of emissions data during refueling experiments provided insight into the travel of gasoline vapor in the refueling system. All the information gathered provides greater understanding of the refueling process and will aid the continued development of CFD models for refueling.
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    High pressure vapor-liquid equilibrium measurements of methane and water mixtures using nuclear magnetic resonance spectroscopy
    (Colorado State University. Libraries, 2021) Sartini, Michael, author; Windom, Bret C., advisor; Widegren, Jason, committee member; Levinger, Nancy, committee member
    Gas composition, which can vary from location to location in natural gas pipelines, constrains the allowable operating conditions and compressor package design. Compressor systems are designed such that they provide the optimal balance between efficiency and gas throughput with safety margins to maintain component lifetime. The presence of liquid in the compressor can lead to excessive wear of intake and discharge valves and impact performance. To prevent ingestion of liquid slugs, operating conditions and separation equipment must be selected appropriately using mixture dew point calculations from commercially available mixture property prediction software such as NIST-REFPROP. NIST-REFPROP is highly reliant on mixture Vapor liquid Equilibrium (VLE) data to predict phases. Thus, there is a need for low uncertainty VLE data for gas mixtures at pressures (1 - 10 MPa) and temperatures (<0 – 100 °C) experienced within natural gas infrastructure, especially for mixtures containing H2O, which would lead to more accurate dew point calculations and allow designers to maximize system performance without compromising component wear and tear. For a mixture comprised completely of hydrocarbon species, VLE calculations at high pressures are accurate as the interaction parameters between the constituents are close to unity and there is typically a wealth of low-uncertainty data available. However, when H2O is present in natural gas significant intermolecular interactions cause the mixture VLE to deviate from ideality. In order to accurately model the VLE of these mixtures, the energy associated with these interactions must be known and accounted for in the calculations. As such, high quality experimental VLE data are needed to improve and validate the thermodynamic models. Nuclear magnetic resonance (NMR) spectroscopy allows for high-quality data collection for water containing samples. This thesis provides the groundwork for using NMR spectroscopy to conduct low-uncertainty VLE measurements of water-hydrocarbon mixtures. Two NMR spectrometers were investigated, and methods were developed to accurately characterize the temperature, pressure, vapor phase and liquid phase molar composition of methane-water systems at equilibrium, the five conditions required for VLE measurement. Preliminary results for low pressure (0-2.06MPa) samples of methane and water showed that the liquid phase methane compositional data taken utilizing NMR spectroscopy significantly deviated from the NISTREFPROP model, revealing the lack of low uncertainty VLE data required to determine the needed interaction parameters for methane and water systems. Future work should target the collection of the high-fidelity methane-water VLE data, and NMR spectroscopy has the potential to perform this task.
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    Modelling and simulation of combustion of dilute syngas fuels in a CFR engine
    (Colorado State University. Libraries, 2019) Padhi, Geet, author; Windom, Bret C., advisor; Olsen, Dan B., committee member; Dandy, David, committee member
    With increasing interest towards discovery of alternative fuels to act as sources of energy, many conventional internal combustion engines are being modified to operate on these new fuels. Optimization of engine specifications including compression ratio, intake/piston geometry, valve timing, and combustion phasing, can greatly improve performance when an engine is modified to operate on alternative fuels such as syngas and producer gas. However, the inability to predict the combustion characteristics of the alternative fuel, such as burn rates and auto-ignition conditions, is a significant challenge when simulation-based design of an engine is intended. The following thesis describes the development of a predictive model to simulate the combustion of a dilute syngas fuel in a Cooperative Fuel Research (CFR) spark ignited engine. The laminar flame speeds of the unique fuel mixtures calculated using CHEMKIN were coupled with the geometric features of the CFR engine to create a combustion model of the CFR engine in GT-POWER. Using two-zone modelling and detailed chemical kinetics, the model is also able to determine the performance of the engine along with any associated knocking tendency of the fuel and its corresponding operating conditions. Validation and tuning of the combustion parameters were performed through comparison to experimental pressure data taken from the CFR engine. The completed engine model can support the design and selection of operating conditions to maximize efficiency of other spark ignited internal combustion engines when powered by the dilute syngas fuel.
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    Physiochemical properties and evaporation dynamics of bioalcohol-gasoline blends
    (Colorado State University. Libraries, 2018) Abdollahipoor, Bahareh, author; Windom, Bret C., advisor; Reardon, Kenneth F., committee member; Olsen, Daniel B., committee member
    After fermentation, the concentration of bioethanol is only 8-12 wt%. To produce anhydrous ethanol fuel, a significant amount of energy is required for separation and dehydration. Once the azeotrope composition is reached, distillation can no longer be exploited for purification and other expensive methods must be used. Replacing anhydrous ethanol fuel with hydrous ethanol (at the azeotrope composition) can result in significant energy and cost savings during production. Currently there is a lack of available thermophysical property data for hydrous ethanol gasoline fuel blends. This data is important to understand the effect of water on critical fuel properties and to evaluate the potential of using hydrous ethanol fuels in conventional and optimized spark ignition engines. In this study, the thermophysical properties, volatility behavior, evaporation dynamic, and mixing/sooting potential of various hydrous and anhydrous ethanol blends with gasoline were characterized. Results show that the properties of low and mid-level hydrous ethanol blends are not significantly different from those of anhydrous ethanol blends, suggesting that hydrous ethanol blends have the potential to be used in current internal combustion engines as a drop-in biofuel. Dual-alcohol approach, mixing lower and higher alcohols with gasoline to obtain a blend with a vapor pressure close to that of the base gasoline, is a potential way to circumvent issues with single alcohol blends. In second project, the azeotropic volatility behavior and mixing/sooting potential of dual-alcohol gasoline blends were studied by monitoring the distillation composition evolution and use of droplet evaporation model.