Topic
Compression ratio
About: Compression ratio is a research topic. Over the lifetime, 12998 publications have been published within this topic receiving 135829 citations.
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TL;DR: In this paper, the effects of ethanol addition to gasoline on an SI engine performance and exhaust emissions are investigated experimentally and theoretically, and the proposed SI engine cycle model has an ability of computing SI engine cycles when using ethanol and ethanol-gasoline blends and it can be used for further extensive parametric studies.
281 citations
TL;DR: In this paper, a model quantum heat engine operating in an Otto cycle is analyzed, where the working medium is composed of an ensemble of harmonic oscillators and changes in volume correspond to changes in the curvature of the potential well.
Abstract: The unavoidable irreversible loss of power in a heat engine is found to be of quantum origin. Following thermodynamic tradition, a model quantum heat engine operating in an Otto cycle is analysed, where the working medium is composed of an ensemble of harmonic oscillators and changes in volume correspond to changes in the curvature of the potential well. Equations of motion for quantum observables are derived for the complete cycle of operation. These observables are sufficient to determine the state of the system and with it all thermodynamical variables. Once the external controls are set, the engine settles to a limit cycle. Conditions for optimal work, power and entropy production are derived. At high temperatures and quasistatic operating conditions, the efficiency at maximum power coincides with the endoreversible result . The optimal compression ratio varies from in the quasistatic limit where the irreversibility is dominated by heat conductance to in the sudden limit when the irreversibility is dominated by friction. When the engine deviates from adiabatic conditions, the performance is subject to friction. The origin of this friction can be traced to the noncommutability of the kinetic and potential energy of the working medium.
270 citations
16 Oct 2006
TL;DR: In this paper, the authors characterize the operating range and conditions required for PPC and show that the combination of low compression ratio, high EGR rate and engine operation close to stoichiometric conditions enables simultaneous NOx and soot reduction at loads of 8bar, 12bar, and 15bar IMEP gross.
Abstract: Partially Premixed Combustion (PPC) provides the potential of simultaneous reduction of NOx and soot for diesel engines. This work attempts to characterize the operating range and conditions required for PPC. The characterization is based on the evaluation of emission and in-cylinder measurement data of engine experiments. It is shown that the combination of low compression ratio, high EGR rate and engine operation close to stoichiometric conditions enables simultaneous NOx and soot reduction at loads of 8bar, 12bar, and 15bar IMEP gross. The departure from the conventional NOx-soot trade-off curve has to be paid with a decline in combustion efficiency and a rise in HC and CO emissions. It is shown that the low soot levels of PPC come along with long ignition delay and low combustion temperature. A further result of this work is that higher inlet pressure broadens the operating range of Partially Premixed Combustion.
266 citations
TL;DR: In this article, the effect of compression ratio on engine performance and exhaust emissions was examined at stoichiometric air/fuel ratio, full load and minimum advanced timing for the best torque MBT in a single cylinder, four stroke, with variable compression ratio and spark ignition engine.
265 citations
TL;DR: In this article, ethanol was used as fuel at high compression ratio to improve performance and to reduce emissions in a small gasoline engine with low efficiency, and it was determined from the experimental results that the most suitable fuel in terms of performance and emissions was E50.
262 citations