Impacts of diesel injection timing and syngas fuel composition in a heavy-duty RCCI engine

2021 ◽  
Vol 247 ◽  
pp. 114759
Author(s):  
Bahram Jafari ◽  
Mahdi Seddiq ◽  
Seyyed Mostafa Mirsalim
Author(s):  
Shuonan Xu ◽  
David Anderson ◽  
Mark Hoffman ◽  
Robert Prucka ◽  
Zoran Filipi

Energy security concerns and an abundant supply of natural gas in the USA provide the impetus for engine designers to consider alternative gaseous fuels in the existing engines. The dual-fuel natural-gas diesel engine concept is attractive because of the minimal design changes, the ability to preserve a high compression ratio of the baseline diesel, and the lack of range anxiety. However, the increased complexity of a dual-fuel engine poses challenges, including the knock limit at a high load, the combustion instability at a low load, and the transient response of an engine with directly injected diesel fuel and port fuel injection of compressed natural gas upstream of the intake manifold. Predictive simulations of the complete engine system are an invaluable tool for investigations of these conditions and development of dual-fuel control strategies. This paper presents the development of a phenomenological combustion model of a heavy-duty dual-fuel engine, aided by insights from experimental data. Heat release analysis is carried out first, using the cylinder pressure data acquired with both diesel-only and dual-fuel (diesel and natural gas) combustion over a wide operating range. A diesel injection timing correlation based on the injector solenoid valve pulse widths is developed, enabling the diesel fuel start of injection to be detected without extra sensors on the fuel injection cam. The experimental heat release trends are obtained with a hybrid triple-Wiebe function for both diesel-only operation and dual-fuel operation. The ignition delay period of dual-fuel operation is examined and estimated with a predictive correlation using the concept of a pseudo-diesel equivalence ratio. A four-stage combustion mechanism is discussed, and it is shown that a triple-Wiebe function has the ability to represent all stages of dual-fuel combustion. This creates a critical building block for modeling a heavy-duty dual-fuel turbocharged engine system.


2021 ◽  
pp. 146808742110012
Author(s):  
Nicola Giramondi ◽  
Anders Jäger ◽  
Daniel Norling ◽  
Anders Christiansen Erlandsson

Thanks to its properties and production pathways, ethanol represents a valuable alternative to fossil fuels, with potential benefits in terms of CO2, NOx, and soot emission reduction. The resistance to autoignition of ethanol necessitates an ignition trigger in compression-ignition engines for heavy-duty applications, which in the current study is a diesel pilot injection. The simultaneous direct injection of pure ethanol as main fuel and diesel as pilot fuel through separate injectors is experimentally investigated in a heavy-duty single cylinder engine at a low and a high load point. The influence of the nozzle hole number and size of the diesel pilot injector on ethanol combustion and engine performance is evaluated based on an injection timing sweep using three diesel injector configurations. The tested configurations have the same geometric total nozzle area for one, two and four diesel sprays. The relative amount of ethanol injected is swept between 78 – 89% and 91 – 98% on an energy basis at low and high load, respectively. The results show that mixing-controlled combustion of ethanol is achieved with all tested diesel injector configurations and that the maximum combustion efficiency and variability levels are in line with conventional diesel combustion. The one-spray diesel injector is the most robust trigger for ethanol ignition, as it allows to limit combustion variability and to achieve higher combustion efficiencies compared to the other diesel injector configurations. However, the two- and four-spray diesel injectors lead to higher indicated efficiency levels. The observed difference in the ethanol ignition dynamics is evaluated and compared to conventional diesel combustion. The study broadens the knowledge on ethanol mixing-controlled combustion in heavy-duty engines at various operating conditions, providing the insight necessary for the optimization of the ethanol-diesel dual-injection system.


Fuel ◽  
2010 ◽  
Vol 89 (3) ◽  
pp. 752-759 ◽  
Author(s):  
G.P. McTaggart-Cowan ◽  
S.N. Rogak ◽  
S.R. Munshi ◽  
P.G. Hill ◽  
W.K. Bushe

Author(s):  
Praveen Kandulapati ◽  
Chuen-Sen Lin ◽  
Dennis Witmer ◽  
Thomas Johnson ◽  
Jack Schmid ◽  
...  

Synthetic fuels produced from non-petroleum based feedstocks can effectively replace the depleting petroleum based conventional fuels while significantly reducing the emissions. The zero sulfur content and the near zero percentage of aromatics in the synthetic fuels make them promising clean fuels to meet the upcoming emissions regulations. However due to their significantly different properties when compared to the conventional fuels; the existing engines must be tested extensively to study their performance with the new fuels. This paper reports a detailed in-cylinder pressure measurement based study made on adaptability of the engine control module (ECM) of a modern heavy duty diesel engine to optimize the engine performance with the F-T diesel fuel. During this study, the F-T and Conventional diesel fuels were tested at different loads and various injection timing changes made with respect to the manufacturer setting. Results from these tests showed that the ECM used significantly different injection timings for the two fuels in the process of optimizing the engine performance. For the same power output the ECM used a 2° advance in the injection timing with respect to the manufacturer setting at the full load and 1° retard at the no load condition. While the injection timings used by the ECM were same for both the fuels at the 50% load condition. However, a necessity for further changes in the control strategies used by the ECM were observed to get the expected advantages with the F-T fuels.


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