Dual-Fuel Combustion in a Heavy-Duty Engine
Doktorsavhandling, 2018

The need to control climate change and improve the fuel effieciency of internal combustion engines has prompted global efforts to develop alternative fuels in order to reduce dependence on conventional petroleum derivatives. This thesis deals with three such alternative fuels: compressed natural gas (CNG), pure methane (used to mimic biogas), and methanol. The first parts of the thesis discuss experimental investigations into conventional gas-Diesel dual-fuel combustion.

The effect of the CNG/methane supplement ratio on engine performance and emissions was explored at two different load points. The results indicated improved performance and emissions at intermediate load more than at low load. In addition, a 3D dual-fuel combustion model developed at Chalmers was validated against experimental data generated during these studies. Reasonably good agreement was achieved between experiment and simulation for most aspects of engine performance, but there were some discrepancies regarding the onset of ignition delay and emissions.

The later parts of the thesis deal with studies on a low temperature combustion concept, Reactivity Controlled Compression Ignition (RCCI), using two alternative fuels: CNG and methanol. Engine performance and emissions were studied for both CNG-Diesel and methanol-Diesel RCCI combustion. Experiments on CNG-Diesel RCCI combustion were performed to explore the effcts of different engine parameters on engine performance and emissions, revealing that high indicated thermal efficiencies (over 50%) could be achieved. However, this combustion strategy presented difficulties when operating at high load and high compression ratios due to the peak incylinder pressure limitation. Another CNG-Diesel RCCI combustion study was therefore conducted, focused on extending the operational load range for this combustion strategy and improving combustion phasing by using late inlet valve closing (IVC). This approach increased the maximum load for CNG-Diesel RCCI combustion by 40% compared to the first CNG-Diesel RCCI study. Finally, experiments on methanol-Diesel RCCI combustion showed that port injection of methanol offered better performance than direct injection of methanol during either the intake stroke or the compression stroke in terms of net indicated thermal efficiency and emissions of HC and CO.

HA3, Hörsalsvägen 4, Chalmers
Opponent: Dr. Bianca Maria Vaglieco, Istituto Motori, Italy


Zhiqin Jia

Chalmers, Mekanik och maritima vetenskaper, Förbränning

The Validation of a Dual-Fuel Combustion Model for Heavy Duty Diesel Engines

FISITA 2014 World Automotive Congress, 2-6 June, Maastricht, the Netherlands,; (2014)

Konferensbidrag (offentliggjort, men ej förlagsutgivet)

Experimental Investigation of Natural Gas-Diesel Dual-Fuel RCCI in a Heavy-Duty Engine

SAE International Journal of Engines,; Vol. 8(2015)p. 797-

Artikel i vetenskaplig tidskrift

Effect of late inlet valve closing on NG-Diesel RCCI combustion in a heavy duty engine

9th International Conference on Modeling and Diagnostics for Advanved Engine Systems, COMODIA 2017, Okayama, Japan, 25-28 July 2017,; (2017)

Paper i proceeding

Zhiqin Jia, Ingemar Denbratt, "Experimental Investigation into the Combustion Characteristics of a Methanol-Diesel Heavy Duty Engine Operated in RCCI mode"

In recent years, the automotive scientific community and vehicle companies have focused considerable research effort on maximizing overall engine efficiency and reducing emissions from internal combustion engines. One of the low temperature combustion concepts, named Reactivity Controlled Compression Ignition (RCCI), has drawn a lot of attention since it could maintain high engine efficiency, lower engine-out emissions, and also effectively control the combustion phasing. The goal of this project is to obtain an in-depth understanding of the dual-fuel RCCI combustion concept. In this project, two alternative fuels (natural gas and methanol) are used as the low-reactivity fuels, which are either port-injected or early direct-injected to form a premixed mixture with air. The high reactivity fuel diesel is direct injected in the cylinder to tune mixture reactivity and control combustion phasing. Experimental investigation of natural gas-Diesel RCCI combustion indicated that high thermal efficiency together with low NOx and soot emissions were obtained. Additionally, direct injection of methanol was studied and compared with port injection of methanol in the attempt to reduce unburned HC and CO emissions from port-injected methanol RCCI combustion. Methanol-Diesel RCCI showed benefit in NOx, soot and CO2 emissions but engine efficiency did not, compared to pure Diesel case. Although these initial experiments using methanol direct injection prototypes didn't reduce emissions of HC and CO compared to port injection of methanol, further optimization of methanol direct injection systems using proper spray targeting and better fuel distribution are expected to improve both fuel economy and emissions.


Annan maskinteknik


Annan kemiteknik



Doktorsavhandlingar vid Chalmers tekniska högskola. Ny serie: 4377


Chalmers tekniska högskola

HA3, Hörsalsvägen 4, Chalmers

Opponent: Dr. Bianca Maria Vaglieco, Istituto Motori, Italy