Change search
ReferencesLink to record
Permanent link

Direct link
Nozzle Coking in CNG-Diesel Dual Fuel Engines
KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Internal Combustion Engines.ORCID iD: 0000-0002-4243-7134
KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.).
2014 (English)In: SAE technical paper series, ISSN 0148-7191, Vol. October, 2014-01-2700Article in journal (Refereed) Published
Abstract [en]

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, , 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.

Place, publisher, year, edition, pages
SAE International , 2014. Vol. October, 2014-01-2700
Keyword [en]
Carbon, Deposits, Diesel engines, Diesel fuels, Engine cylinders, Engines, Fuels, Nozzles, Petroleum deposits, Powertrains, Zinc, High temperature, Injector nozzle, Low injection pressure, Nozzle temperature, Single cylinder engine, Standardized tests, Start of injections, Steady-state flows, Dual fuel engines
National Category
Mechanical Engineering
URN: urn:nbn:se:kth:diva-176216DOI: 10.4271/2014-01-2700ScopusID: 2-s2.0-84938497558OAI: diva2:871687
SAE 2014 International Powertrains, Fuels and Lubricants Meeting, FFL,20 October 2014 - 22 October 2014

QC 20151116

Available from: 2015-11-16 Created: 2015-11-02 Last updated: 2015-11-16Bibliographically approved

Open Access in DiVA

No full text

Other links

Publisher's full textScopus

Search in DiVA

By author/editor
Risberg, PerÅngström, Hans-Erik
By organisation
Internal Combustion EnginesMachine Design (Dept.)
In the same journal
SAE technical paper series
Mechanical Engineering

Search outside of DiVA

GoogleGoogle Scholar
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

Altmetric score

Total: 63 hits
ReferencesLink to record
Permanent link

Direct link