Nozzle coking in diesel engines has received a lot of attention in recent years. High temperature in the nozzle tip is one of the key factors known to accelerate this process. In premixed CNG-diesel dual fuel, DDF, engines a large portion of the diesel fuel through the injector is removed compared to regular diesel operation. This can result in very high nozzle temperatures. Nozzle hole coking can therefore be expected to pose a significant challenge for DDF operation.In this paper an experimental study of nozzle coking has been performed on a DDF single cylinder engine. The objective was to investigate how the rate of injector nozzle hole coking during DDF operation compares to diesel operation. In addition to the nozzle tip temperature, the impact of other parameters on coking rate was also of interest.Start of injection, λ, diesel substitution ratio and common rail pressure were varied in two levels starting from a common baseline case, resulting in a total of 10 operating cases. These cases were run for three and a half hours in steady-state, using standard injectors and zinc contaminated diesel to accelerate the coking process. The zinc was added in form of zinc neodecanoate, similar to the practice in the standardized tests used to study nozzle coking in diesel engines.After the tests the injectors were disassembled and the steady state flow through the injector nozzles was measured to isolate the effect of nozzle hole coking. The results show significant coking from only a few hours of testing. The most challenging case was the combination of high nozzle tip temperature from DDF operation with low injection pressure. The flow loss from operation in DDF mode was far more severe compared to diesel operation. Elemental analysis of the deposits shows similar composition resulting from diesel and DDF operation. In the DDF deposits higher concentrations of elements from the engine oil were found in addition to higher carbon content. It is concluded that injector nozzle coking is a challenge which requires appropriate attention when developing DDF engines.


    Access

    Check access

    Check availability in my library

    Order at Subito €


    Export, share and cite



    Title :

    Nozzle Coking in CNG-Diesel Dual Fuel Engines


    Additional title:

    Sae Technical Papers


    Contributors:

    Conference:

    SAE 2014 International Powertrain, Fuels & Lubricants Meeting ; 2014



    Publication date :

    2014-10-13




    Type of media :

    Conference paper


    Type of material :

    Print


    Language :

    English




    Nozzle Coking in CNG-Diesel Dual Fuel Engines

    Konigsson, F. / Risberg, P. / Angstrom, H.-E. et al. | British Library Conference Proceedings | 2014


    Influence on injection nozzle coking in diesel engines

    Grueting,U. / Pischinger,S. / Tang,J. et al. | Automotive engineering | 2009


    Coking phenomena in nozzle orifices of DI diesel engines

    Tang,J. / Pischinger,S. / Lamping,M. et al. | Automotive engineering | 2009


    Coking Phenomena in Nozzle Orifices of Dl-Diesel Engines

    Tomazic, Dean / Tang, Jens / Tatur, Marek et al. | SAE Technical Papers | 2009


    Injector Nozzle Coking With Oxygenated Diesel

    Hansen, Alan C. / Reid, John F. / Mendoza, Michael C. et al. | SAE Technical Papers | 2001