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  • 1.
    Bernemyr, Hanna
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.).
    Ström, Johan
    Westlund, Anders
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.).
    Experimental Evaluation of a Rotating Disc DiluterIn: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851Article in journal (Refereed)
  • 2.
    Lindström, Mikael
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Internal Combustion Engines.
    Westlund, Anders
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Internal Combustion Engines.
    Ångström, Hans-Erik
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Internal Combustion Engines.
    A study of combustion and emission formation characteristics during production engine transients using optical diagnostics2011In: Proceedings of the Institution of mechanical engineers. Part D, journal of automobile engineering, ISSN 0954-4070, E-ISSN 2041-2991, Vol. 225, no D9, p. 1290-1303Article in journal (Refereed)
    Abstract [en]

    In order to identify some of the special combustion and emission formation phenomena that occur in a turbocharged heavy-duty diesel engine during transient operation, the transient strategy of a production engine has been characterized at four different engine speeds. From each transient some points have been selected for further investigation by recreating these load points as steady-state points in a single-cylinder engine. This allows the emissions to be measured with a high degree of accuracy. An endoscope which makes it possible to evaluate flame temperatures was used in both engines. An empirically derived method of calculating nitric oxide (NO) formation from a combination of measured flame temperature, calculated gas temperature, and heat release rate has been developed and applied. This provides an increased understanding of combustion and emission formation phenomena during transient operation. An optical engine was also used to provide a full combustion chamber view for some of the operating points, and a specially developed software was used to calculate temperature distributions based on high-speed camera colour information. The NO formation formula was applied on these images, which resulted in spatially resolved NO formation distributions.

  • 3.
    Westlund, Anders
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Internal Combustion Engines.
    Simplified models for emission formation in diesel engines during transient operation2011Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The work presented in this thesis is the result of the KTH CICERO project “Dynamic Engine Performance” in which the main objective was to develop simple models foremission formation. The demand for such models is increasing, mainly due to the tightening emission legislation for diesel engines which has lead to more complex engines and thereby more laborious development and calibration processes. Simple emission models can be a valuable tool during the development phase, e.g. when used with models for gas exchange - and after-treatment systems, and for precalibration of the engine control settings. Since engines in automotive application typically work under dynamic load, the main prerequisites were that the models should be comprehensive enough to handle the extreme conditions that can occur in engines during load transients but still simple enough to be used for calibration.

    Two main approaches have been used; one where the combustion and emission formation processes were modeled from the flame front and downstream using equilibrium chemistry. In the other approach, the entire mixing/entrainment process was modeled and emission formation was modeled with kinetic chemistry. Both approaches were found to meet the requirements but had different advantages; the first, simpler approach had shorter calculation time while the latter was more comprehensive and required less tuning. The latter also resulted in a model for heat release rate which can be useful as a stand-alone model and allows the emission models to be used for untested conditions.

    Another objective in this project was to identify techniques/instruments that can be used for emission measurements during transient operation since these are essential for understanding of emission formation in these conditions and as validation data for the emission models.

  • 4.
    Westlund, Anders
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Internal Combustion Engines.
    Lindström, Mikael
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Internal Combustion Engines.
    Ångström, Hans-Erik
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Internal Combustion Engines.
    A 1-D Model for Heat Release Rate and Emission Formation in Diesel Engines Based on Correlations for Entrainment Rate, Lift-Off Length and Ignition Delay: Validation for Transient ConditionsArticle in journal (Other academic)
  • 5.
    Westlund, Anders
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Internal Combustion Engines.
    Lindström, Mikael
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Internal Combustion Engines.
    Ångström, Hans-Erik
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Internal Combustion Engines.
    A one-dimensional model for heat release rate and emission formation in diesel engines based on correlations for entrainment rate, lift-off length and ignition delay: Validation for transient conditions2012In: Proceedings of the Institution of mechanical engineers. Part D, journal of automobile engineering, ISSN 0954-4070, E-ISSN 2041-2991, Vol. 226, no D9, p. 1243-1258Article in journal (Refereed)
    Abstract [en]

    A simplified one-dimensional model for combustion and emission formation in diesel engines has been developed in a project where the long-term objective is to predict the emissions during transient operation. The models are intended to be used as a tool for pre-development of after-treatment systems and for offline calibration of engine controls. These applications imply that the final model must be both computationally inexpensive and comprehensive. The model is based on a correlation for the air entrainment rate which is applied to a discretized injection event. On this, the combustion rate and the emission formation rate are imposed with simple models. In this publication, the model is validated for the targeted conditions and transient operation. The model is based on a previously presented model which was evaluated for steady state conditions. The model presented here has been modified to address the shortcomings that were identified in the previous evaluation. The model was able to predict the heat release rate and the emissions of nitrogen oxide ( NO) and soot with reasonable accuracy and also the requirement regarding the computational time was met. The average time for simulation of one engine cycle was approximately 3 s on a standard laptop.

  • 6.
    Westlund, Anders
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Internal Combustion Engines.
    Pickett, Lyle M.
    Modelling soot precursor formation in reacting jets with simple fluid mechanics and detailed chemical mechanismsArticle in journal (Other academic)
  • 7.
    Westlund, Anders
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Internal Combustion Engines.
    Ångström, Hans-Erik
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Internal Combustion Engines.
    Llindström, Mikael
    Validation of a Simplified Model for Combustion and Emission Formation in Diesel Engines Based on Correlations for Spray Penetration and Dispersion, Gas Entrainment into Sprays and Flame Lift-off2010In: International Powertrains, Fuels & Lubricants Meeting, 2010, no 01-1494Conference paper (Refereed)
    Abstract [en]

    A simplified combustion and emission formation model for diesel engines has been developed in a project where the long term objective is to predict emissions during transient operation. The intended application implies that the final model must be both computationally inexpensive and comprehensive so that it can be used for optimization of engine control variables when coupled to full-engine simulation software. As starting point, the proposed model uses diesel spray correlations established in combustion vessels regarding spray penetration, dispersion, gas entrainment, ignition and flame lift-off. It has been found that with minor adaption, these correlations are valid also for combustion in an engine. By assuming a fully mixing controlled combustion after ignition and by use of simplified emission models, the correlations have been found useful for predicting trends in engine-out emission with low computational cost. Besides engine-out emissions and pressure analysis, endoscope instrumentation has been used to provide validation data regarding maximum in-cylinder temperature and soot concentration.

1 - 7 of 7
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