The Experts below are selected from a list of 23016 Experts worldwide ranked by ideXlab platform

Stefan Pischinger - One of the best experts on this subject based on the ideXlab platform.

  • homogeneous charge compression ignition Combustion Stability improvement using a rapid ignition system
    International Journal of Engine Research, 2020
    Co-Authors: David Gordon, Stefan Pischinger, Christian Wouters, Shota Kinoshita, Maximilian Wick, Bastian Lehrheuer, Jakob Andert, Charles Robert Koch
    Abstract:

    When compared to traditional engines, homogeneous charge compression ignition has the potential to significantly reduce NOx raw emissions, while maintaining a high fuel efficiency. Homogeneous char...

  • Tailor-Made Fuels from Biomass: Potentials of 2-butanone and 2-methylfuran in direct injection spark ignition engines
    Fuel, 2016
    Co-Authors: Fabian Hoppe, Ultan Burke, A. Heufer, Matthias Thewes, Friedrich Kremer, Stefan Pischinger
    Abstract:

    Two possible future biofuels, 2-butanone also referred to as methyl ethyl ketone (MEK) and 2-methylfuran, identified within the Cluster of Excellence "Tailor-Made Fuels from Biomass" (TMFB), have been evaluated as pure fuels in the present study. Investigations of the autoignition tendency were carried out on a rapid compression machine (RCM), whereas thermodynamic investigations were conducted on a direct injection spark ignition single cylinder research engine. 2-Methylfuran and 2-butanone were compared against the present benchmark biofuel for spark ignition engines ethanol and conventional RON95 gasoline. A similar autoignition tendency compared to ethanol was found for 2-methylfuran. In case of 2-butanone very high ignition delay times were measured, even higher than for ethanol and 2-methylfuran. For 2-butanone and 2-methylfuran, the lower heat of vaporization in combination with higher vapor pressure and better primary breakup compared to ethanol are beneficial for mixture formation. During the engine testing for both fuels, superior characteristics compared to conventional gasoline and ethanol were identified. In case of 2-methylfuran, an increased Combustion Stability, especially at low engine load and cold boundary conditions, could be found at a higher knock resistance than conventional gasoline. In combination with increased compression ratio this enables an efficiency increase of up to 19%, whereas for ethanol an even further increase of up to 21% is possible. 2-Butanone shows increased Combustion Stability at low engine load and cold boundary conditions compared to ethanol and also conventional gasoline as well as highest knock resistance equal to ethanol. However, for both 2-butanone and 2-methylfuran increased emissions of nitrogen oxides were found when compared to ethanol. For both possible future biofuels and also ethanol, a significant reduction of particle emissions compared to conventional gasoline was found.

  • analysis of the impact of 2 methylfuran on mixture formation and Combustion in a direct injection spark ignition engine
    Energy & Fuels, 2011
    Co-Authors: Matthias Thewes, Stefan Pischinger, Martin Muether, Matthias Budde, Andre Brunn, Andreas Sehr, Philipp Adomeit, Juergen Klankermayer
    Abstract:

    Within the Cluster of Excellence “Tailor-Made Fuels from Biomass”, a new reaction sequence to transform biomass into 2-methylfuran has been developed. In the present study, the influence of this potential biofuel on in-cylinder spray formation and evaporation as well as engine performance is studied experimentally using a direct-injection spark-ignition single-cylinder research engine. The results obtained for 2-methylfuran are benchmarked against investigation on the same engine using conventional research octane number (RON) 95 fuel and ethanol. The in-cylinder spray formation and evaporation process is characterized by high-speed Mie scattering visualizations, indicating quicker evaporation of 2-methylfuran compared to ethanol. Engine experiments support the findings of the optical measurements by revealing excellent Combustion Stability, especially in cold conditions, combined with a hydrocarbon emission reduction of at least 61 % in the relevant spark timing range compared to conventional fuel. The e...

Oh Chae Kwon - One of the best experts on this subject based on the ideXlab platform.

  • Combustion Stability of gaseous ch4 o2 and h2 o2 coaxial jet flames in a single element combustor
    Energy, 2017
    Co-Authors: Sun Choi, Tae Young Kim, Hee Kyung Kim, Inseuck Jeung, Jaye Koo, Oh Chae Kwon
    Abstract:

    Abstract In order to understand the Combustion Stability of a methane (CH4)/oxygen (O2) bipropellant as a next-generation rocket liquid propellant, the Combustion Stability limits and morphology of gaseous CH4/O2 (GCH4/GO2) coaxial jet flames, among various phases, in a single-element combustor are experimentally studied compared with the gaseous hydrogen/O2 (GH2/GO2) coaxial jet flames. Only the stably attached flame and blowoff regimes are observed for both the GCH4/GO2 and GH2/GO2 flames, showing the flame thickness smaller than the injector lip thickness. Although the Combustion Stability limits of the GCH4/GO2 flames are narrower than the GH2/GO2 flames, practical use of CH4 in rocket engine applications seems to be acceptable since the fuel-rich CH4/O2 flames show very stabilized and intensified burning. For the GCH4/GO2 flames, the outer flame generated by the recirculating O2 is relatively weak and OH∗ is distributed up to the downstream. With increasing O2 injection velocity the length of the GCH4/GO2 flames and the location at the maximum OH∗ intensity increase even under turbulent Combustion condition, due to the saturated enhancement of CH4-O2 diffusivity and the strong burning of pure O2 near the injector lip. The present results provide a useful database to model Combustion of CH4/O2 bipropellants under various phases.

  • Combustion Stability limits and nox emissions of nonpremixed ammonia substituted hydrogen air flames
    International Journal of Hydrogen Energy, 2013
    Co-Authors: J M Joo, Seungro Lee, Oh Chae Kwon
    Abstract:

    Abstract The Combustion Stability (extinction) limits and nitrogen oxide (NO x ) emissions of nonpremixed ammonia (NH 3 )–hydrogen (H 2 )–air flames at normal temperature and pressure are studied to evaluate the potential of partial NH 3 substitution for improving the safety of H 2 use and to provide a database for the nonpremixed NH 3 -substituted H 2 –air flames. Considering coflow nonpremixed NH 3 –H 2 –air flames for a wide range of fuel and coflow air injection velocities ( V fuel and V coflow ) and the extent of NH 3 substitution, the effects of NH 3 substitution on the Stability limits and NO x emissions of the NH 3 –H 2 –air flames are experimentally determined, while the nonpremixed NH 3 –H 2 –air flame structure is computationally predicted using a detailed reaction mechanism. Results show significant reduction in the Stability limits and unremarkable increase in the NO x emission index for enhanced NH 3 substitution, supporting the potential of NH 3 as an effective, carbon-free additive in nonpremixed H 2 –air flames. With increasing V coflow the NO x emission index decreases, while with increasing V fuel it decreases and then increases due to the recirculation of burned gas and the reduced radiant heat losses, respectively. Given V coflow / V fuel the flame length increases with enhanced NH 3 substitution since more air is needed for reaction stoichiometry. The predicted flame structure shows that NH 3 is consumed more upstream than H 2 due to the difference between their diffusivities in air.

  • effects of ammonia substitution on Combustion Stability limits and nox emissions of premixed hydrogen air flames
    International Journal of Hydrogen Energy, 2012
    Co-Authors: J M Joo, Seungro Lee, Oh Chae Kwon
    Abstract:

    Abstract The Combustion Stability limits and nitrogen oxide (NOx) emissions of burner-stabilized premixed flames of ammonia (NH3)-substituted hydrogen (H2)–air mixtures at normal temperature and pressure are studied to evaluate the potential of partial NH3 substitution to improve the safety of H2 use. The effects of NH3 substitution, nitrogen (N2) coflow and mixture injection velocity on the Stability limits and NOx emissions of NH3–H2–air flames are experimentally determined. Results show a reduction of Stability limits with NH3 substitution and coflow, supporting the potential of NH3 as a carbon-free, green additive in H2–air flames and indicating a different tendency from that for no coflow condition. The NOx emission index is almost constant even with enhanced NH3 substitution, though the absolute value of NOx emissions increases in general. At fuel-rich conditions, the NOx emission index decreases with increasing mixture injection velocity and the existence of coflow. The thermal deNOx process in the post-flame region is involved in reducing NOx emissions for the fuel-rich flames.

Matthias Thewes - One of the best experts on this subject based on the ideXlab platform.

  • Tailor-Made Fuels from Biomass: Potentials of 2-butanone and 2-methylfuran in direct injection spark ignition engines
    Fuel, 2016
    Co-Authors: Fabian Hoppe, Ultan Burke, A. Heufer, Matthias Thewes, Friedrich Kremer, Stefan Pischinger
    Abstract:

    Two possible future biofuels, 2-butanone also referred to as methyl ethyl ketone (MEK) and 2-methylfuran, identified within the Cluster of Excellence "Tailor-Made Fuels from Biomass" (TMFB), have been evaluated as pure fuels in the present study. Investigations of the autoignition tendency were carried out on a rapid compression machine (RCM), whereas thermodynamic investigations were conducted on a direct injection spark ignition single cylinder research engine. 2-Methylfuran and 2-butanone were compared against the present benchmark biofuel for spark ignition engines ethanol and conventional RON95 gasoline. A similar autoignition tendency compared to ethanol was found for 2-methylfuran. In case of 2-butanone very high ignition delay times were measured, even higher than for ethanol and 2-methylfuran. For 2-butanone and 2-methylfuran, the lower heat of vaporization in combination with higher vapor pressure and better primary breakup compared to ethanol are beneficial for mixture formation. During the engine testing for both fuels, superior characteristics compared to conventional gasoline and ethanol were identified. In case of 2-methylfuran, an increased Combustion Stability, especially at low engine load and cold boundary conditions, could be found at a higher knock resistance than conventional gasoline. In combination with increased compression ratio this enables an efficiency increase of up to 19%, whereas for ethanol an even further increase of up to 21% is possible. 2-Butanone shows increased Combustion Stability at low engine load and cold boundary conditions compared to ethanol and also conventional gasoline as well as highest knock resistance equal to ethanol. However, for both 2-butanone and 2-methylfuran increased emissions of nitrogen oxides were found when compared to ethanol. For both possible future biofuels and also ethanol, a significant reduction of particle emissions compared to conventional gasoline was found.

  • analysis of the impact of 2 methylfuran on mixture formation and Combustion in a direct injection spark ignition engine
    Energy & Fuels, 2011
    Co-Authors: Matthias Thewes, Stefan Pischinger, Martin Muether, Matthias Budde, Andre Brunn, Andreas Sehr, Philipp Adomeit, Juergen Klankermayer
    Abstract:

    Within the Cluster of Excellence “Tailor-Made Fuels from Biomass”, a new reaction sequence to transform biomass into 2-methylfuran has been developed. In the present study, the influence of this potential biofuel on in-cylinder spray formation and evaporation as well as engine performance is studied experimentally using a direct-injection spark-ignition single-cylinder research engine. The results obtained for 2-methylfuran are benchmarked against investigation on the same engine using conventional research octane number (RON) 95 fuel and ethanol. The in-cylinder spray formation and evaporation process is characterized by high-speed Mie scattering visualizations, indicating quicker evaporation of 2-methylfuran compared to ethanol. Engine experiments support the findings of the optical measurements by revealing excellent Combustion Stability, especially in cold conditions, combined with a hydrocarbon emission reduction of at least 61 % in the relevant spark timing range compared to conventional fuel. The e...

Juergen Klankermayer - One of the best experts on this subject based on the ideXlab platform.

  • analysis of the impact of 2 methylfuran on mixture formation and Combustion in a direct injection spark ignition engine
    Energy & Fuels, 2011
    Co-Authors: Matthias Thewes, Stefan Pischinger, Martin Muether, Matthias Budde, Andre Brunn, Andreas Sehr, Philipp Adomeit, Juergen Klankermayer
    Abstract:

    Within the Cluster of Excellence “Tailor-Made Fuels from Biomass”, a new reaction sequence to transform biomass into 2-methylfuran has been developed. In the present study, the influence of this potential biofuel on in-cylinder spray formation and evaporation as well as engine performance is studied experimentally using a direct-injection spark-ignition single-cylinder research engine. The results obtained for 2-methylfuran are benchmarked against investigation on the same engine using conventional research octane number (RON) 95 fuel and ethanol. The in-cylinder spray formation and evaporation process is characterized by high-speed Mie scattering visualizations, indicating quicker evaporation of 2-methylfuran compared to ethanol. Engine experiments support the findings of the optical measurements by revealing excellent Combustion Stability, especially in cold conditions, combined with a hydrocarbon emission reduction of at least 61 % in the relevant spark timing range compared to conventional fuel. The e...

Yasuo Moriyoshi - One of the best experts on this subject based on the ideXlab platform.

  • Improvement of thermal efficiency of a four-cylinder gasoline homogeneous charge compression ignition engine via blowdown supercharging
    International Journal of Engine Research, 2012
    Co-Authors: Tatsuya Kuboyama, Yasuo Moriyoshi, Yasuhiro Urata, Koichi Hatamura, Junichi Takanashi, Toshio Yamada
    Abstract:

    The objective of this study is to develop a practical technique to achieve homogeneous charge compression ignition operation with a wide operating range using a blowdown supercharge system, which has been previously demonstrated as an effective technique to extend the upper load limit of acceptable homogeneous charge compression ignition operation. The valve actuation strategy to attain acceptable homogeneous charge compression ignition operation in a wide operating range has been newly developed and experimentally examined. The proposed strategy provides high in-cylinder temperature and a relatively small amount of in-cylinder mixture during low-load operations to improve the Combustion Stability while providing a large amount of diluted mixture for high-load operations to keep the in-cylinder pressure rise rate and nitrogen oxide emissions low. In addition, thermal efficiency and exhaust emissions for various homogeneous charge compression ignition operating loads using the blowdown supercharge system w...

  • The influences of hydrogen on the performance and emission characteristics of a heavy duty natural gas engine
    International Journal of Hydrogen Energy, 2011
    Co-Authors: Cheolwoong Park, Chang-gi Kim, Young Choi, Sang-yeon Won, Yasuo Moriyoshi
    Abstract:

    Because blending hydrogen with natural gas can allow the mixture to burn leaner, reducing the emission of nitrogen oxide (NOx), hydrogen blended with natural gas (HCNG) is a viable alternative to pure fossil fuels because of the effective reduction in total pollutant emissions and the increased engine efficiency. In this research, the performance and emission characteristics of an 11-L heavy duty lean burn engine using HCNG were examined, and an optimization strategy for the control of excess air ratio and of spark advance timing was assessed, in consideration of Combustion Stability. The thermal efficiency increased with the hydrogen addition, allowing stable Combustion under leaner operating conditions. The efficiency of NOx reduction is closely related to the excess air ratio of the mixture and to the spark advance timing. With the optimization of excess air ratio and spark advance timing, HCNG can effectively reduce NOx as much as 80%.