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The Influence of In-Cylinder Flows on Emissions and Heat Transfer from Methane-Diesel Dual Fuel Combustion
KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Internal Combustion Engines.
KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Internal Combustion Engines.
KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Internal Combustion Engines.
2013 (English)In: SAE International Journal of Engines, ISSN 1946-3936, Vol. 6, no 4Article in journal (Refereed) Published
Abstract [en]

In order for premixed methane diesel dual fuel engines to meet current and future legislation, the emissions of unburned hydrocarbons must be reduced while high efficiency and high methane utilization is maintained. This paper presents an experimental investigation into the effects of in cylinder air motion, swirl and tumble, on the emissions, heat transfer and combustion characteristics of dual fuel combustion at different air excess ratios. Measurements have been carried out on a single cylinder engine equipped with a fully variable valve train, Lotus AVT. By applying different valve lift profiles for the intake valves, the swirl was varied between 0.5 and 6.5 at BDC and the tumble between 0.5 and 4 at BDC. A commercial 1D engine simulation tool was used to calculate swirl number and tumble for the different valve profiles. Input data for the simulation software was generated using a steady-state flow rig with honeycomb torque measurements. To measure heat transfer, thermocouples were fitted in the cylinder head and heat exchangers on the coolant circuit and the engine oil. The study shows that swirl has a strong effect on the heat transfer; increasing the swirl from 0.5 to 6.5 increases the heat transfer to the coolant by 50%. With regards to emissions; swirl has the effect of increasing oxidation of hydrocarbons returning from crevices. For this reason a 20% reduction of hydrocarbon emissions can be achieved by increasing the swirl from 0.4 to 3. At high λ of 1.9, combustion is very sensitive to mixing between the gas and the air. The mixing is affected by the turbulence generated over the intake valves. A difference in engine out HC emissions by a factor of two can be achieved by varying the valve lift curve and hence varying the turbulence generated during the intake event. The timing of the gas injection can also improve mixing and achieve similar results. Compared to SI, dual fuel combustion is relatively insensitive to tumble.

Place, publisher, year, edition, pages
2013. Vol. 6, no 4
Keyword [en]
Combustion characteristics, Different valve lift, Experimental investigations, Hydrocarbon emission, In-cylinder air motions, Single cylinder engine, Unburned hydrocarbons, Variable valve train, Combustion, Computer software, Coolants, Dual fuel engines, Heat transfer, Intake valves, Methane, Mixing, Thermocouples, Turbulence, Engine cylinders
National Category
Mechanical Engineering
Identifiers
URN: urn:nbn:se:kth:diva-140058DOI: 10.4271/2013-01-2509Scopus ID: 2-s2.0-84886613446OAI: oai:DiVA.org:kth-140058DiVA: diva2:688798
Note

QC 20140117

Available from: 2014-01-17 Created: 2014-01-16 Last updated: 2014-09-15Bibliographically approved
In thesis
1. On Combustion in the CNG-Diesel Dual Fuel Engine
Open this publication in new window or tab >>On Combustion in the CNG-Diesel Dual Fuel Engine
2014 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Currently there is a large interest in alternative transport fuels. There are two underlying reasons for this interest: the desire to decrease the environmental impact of transports and the need to compensate for the declining availability of petroleum. In the light of both these factors, the CNG-diesel dual fuelengine is an attractive concept. The primary fuel of the dual fuel engine is methane, which can be derived both from renewables and from fossil sources. Methane from organic waste, commonly referred to as biomethane, can provide a reduction in greenhouse gases unmatched by any other fuel. Furthermore, fossil methane, natural gas, is one of the most abundant fossil fuels.Thedual fuelengine is, from a combustion point of view, a hybridof the diesel and theOtto-engineand it shares characteristics with both.

From a market standpoint, the dual fuel technology is highly desirable; however, from a technical point of view it has proven difficult to realize. The aim of this project was to identify limitations to engine operation, investigate these challenges, and ,as much as possible, suggest remedies. Investigations have been made into emissions formation, nozzle-hole coking, impact of varying in-cylinder air motion, behavior and root causes of pre-ignitions, and the potential of advanced injection strategies and unconventional combustion modes. The findings from each of these investigations have been summarized, and recommendations for the development of a Euro 6 compliant dual fuel engine have been formulated. Two key challenges must be researched further for this development to succeed: an aftertreatment system which allows for low exhaust temperatures must be available, and the root cause of pre-ignitions must be found and eliminated.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2014. x, 98 p.
Series
TRITA-MMK, ISSN 1400-1179 ; 2014:08
National Category
Energy Engineering
Research subject
Machine Design
Identifiers
urn:nbn:se:kth:diva-151188 (URN)978-91-7595-243-7 (ISBN)
Public defence
2014-09-26, Kollegiesalen, Brinellvägen 8, KTH, Stockholm, 14:00 (English)
Opponent
Supervisors
Funder
Swedish Energy Agency
Note

QQC 20140915

Available from: 2014-09-15 Created: 2014-09-15 Last updated: 2014-09-15Bibliographically approved

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