Browsing by Subject "HCCI"

Now showing 1 - 4 of 4
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    Effects of homogeneous charge compression ignition (HCCI) control strategies on particulate emissions of ethanol fuel.
    (2010-12) Franklin, Luke
    This thesis presents a systematic investigation into the formation of particulate matter in homogeneous charge compression ignition (HCCI) engines. These engines are representative of the emerging generation of low sooting engine technology. Early research in the field concluded that engines operating with this combustion strategy could offer Diesel like efficiency while simultaneously reducing emissions of particulate matter and the oxides of nitrogen to nearly negligible levels. While quantification of gas phase emissions has changed little through modern regulatory history, the metrics defining particulate emissions and the state of understanding of the research community are rapidly evolving. Advances in technology for characterizing particulate emissions from spark ignition and compression ignition engines have been applied to HCCI emissions and the results indicate the production of significant quantities, by both number and mass, of particles from the HCCI combustion strategy. A relationship has been identified between in-cylinder behavior, and both gaseous and particulate emissions. It has been shown to be valid for 2 different fuels and multiple engine loads. Characteristics of the particulate matter suggest it is formed via gas to particle conversion, or nucleation, of the lighter distillates from the engines lubricating oil.
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    Miniature HCCI Engine Compressor
    (2015-06) Johnson, Dustin
    Hydrocarbon fuels have a much higher specific energy than electric batteries, and are thus a desirable power supply for portable devices. A reliable lightweight long lasting power supply will be an enabler for human assist devices and miniature robotics. A prototype miniature free-piston engine compressor runs for up to 30 s. New pistons and cylinder liners with coatings did not improve reliability when implemented in the engine. The engine stalled because pressure could not be held in the cylinder due to blow-by leakage caused by too large of piston/cylinder clearance. The air compressor part of the device was tested independently. It reached a pressure difference of 450 kPa and produced a maximum 11 W of compressed air power when working against a backpressure of 170 kPa. Two thermodynamic models of the air compressor were created which matched experimental results but did not capture all the details of compressor operation.
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    Miniature homogeneous charge compression ignition free-piston engine compressor
    (2013-06) Tian, Lei
    Utilizing the high energy density of hydrocarbon fuels, an internal combustion engine based free-piston engine compressor is a promising solution as a power supply for miniature size mobile fluid power applications. A free-piston engine is a type of engine without crankshaft, and piston motion depends on force balance instead of mechanical constraints. Homogeneous charge compression ignition (HCCI) is a combustion mode in which homogeneous fuel air mixture is compressed to the point of auto-ignition. The objective of the thesis work is building a miniature size engine compressor to work as a compact fluid power supply, while combining the HCCI and free-piston engine configuration. Mathematical models for components were calibrated and verified by components testing. The overall engine compressor model correlated well with testing results of a proof-of-concept prototype. Although the prototype only achieved 0.6% overall efficiency from fuel energy to cooled compressed air because of poor compressor efficiency and high fuel short circuiting loss, the miniature free-piston engine compressor showed the potential to be a high energy density, compact fluid power supply.
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    Synthesis gas use in internal combustion engines.
    (2010-12) Bika, Anil Singh
    The objective of this dissertation was to investigate the combustion characteristics of a compression ignition, spark ignition, and homogeneous charge compression ignition engine operating on various blends of synthesis gas. To fully investigate the three ICE operating regimes, experimental investigations were carried out to focus on: 1.) A CI engine operating on ethanol and hydrogen fuel 2.) A CI engine operating on diesel fuel with varying blends of synthesis gas 3.) A SI engine operating on varying blends of synthesis gas 4.) An HCCI engine operating on hydrogen fuel 5.) An HCCI engine operating on varying blends of synthesis gas The three operating modes (CI, SI, and HCCI) were selected because it is unlikely that an engine will be able to operate solely in an HCCI regime throughout the complete load range. The more common CI and SI regimes will likely be necessary for high load engine operation. The results from this doctoral work sheds light into the fundamental aspects of syngas combustion and also provides a foundation for future gasification plant designers and synthesis gas producers, regarding the fuel composition needs of a syngas powered internal combustion engine. The first 3 chapters of this dissertation provide an introduction and background for this doctoral work. The remaining chapters present the results and conclusions