Air-System and Variable Valve Actuation Recipe for High Load Gasoline Compression Ignition Operation in a Heavy-Duty Diesel Engine

2021 ◽  
Author(s):  
Praveen Kumar ◽  
Yu Zhang ◽  
Michael Traver ◽  
John Watson
Keyword(s):  
Diesel Engine ◽  
High Load ◽  
Compression Ignition ◽  
Heavy Duty ◽  
Variable Valve Actuation ◽  
Air System ◽  
Heavy Duty Diesel Engine ◽  
Heavy Duty Diesel ◽  
Variable Valve ◽  
Valve Actuation

Impact of Geometric Compression Ratio and Variable Valve Actuation on Gasoline Compression Ignition in a Heavy-Duty Diesel Engine

2020 ◽  
Author(s):  
Yu Zhang ◽  
Praveen Kumar ◽  
Meng Tang ◽  
Yuanjiang Pei ◽  
Brock Merritt ◽  
...  
Keyword(s):  
Compression Ratio ◽  
Premixed Combustion ◽  
Compression Ignition ◽  
Heavy Duty ◽  
Variable Valve Actuation ◽  
Partially Premixed Combustion ◽  
Heavy Duty Diesel Engine ◽  
Heavy Duty Diesel ◽  
Variable Valve ◽  
Valve Actuation

Abstract Gasoline compression ignition (GCI) is a promising powertrain solution to simultaneously address the increasingly stringent regulation of oxides of nitrogen (NOx) and a new focus on greenhouse gases. GCI combustion benefits from extended mixing times due to the low reactivity of gasoline, but only when held beneath the threshold of the high temperature combustion regime. The geometric compression ratio (GCR) of an engine is often chosen to balance the desire for low NOx emissions while maintaining high efficiency. This work explores the relationship between GCR, variable valve actuation (VVA) and emissions when using GCI combustion strategies. The test article was a Cummins ISX15 heavy-duty diesel engine with an unmodified production air and fuel system. The test fuel was an ethanol-free gasoline with a market-representative research octane number (RON) of 91.4–93.2. In the experimental investigation at 1375 rpm/10 bar BMEP, three engine GCRs were studied, including 15.7, 17.3, and 18.9. Across the three GCRs, GCI exhibited a two-stage combustion process enabled through a split injection strategy. When keeping both NOx and CA50 constant, varying GCR from 15.7 to 18.9 showed only a moderate impact on engine brake thermal efficiency (BTE), while its influence on smoke was pronounced. At a lower GCR, a larger fraction of fuel could be introduced during the first injection event due to lower charge reactivity, thereby promoting partially-premixed combustion and reducing smoke. Although increasing GCR increased gross indicated thermal efficiency (ITEg), it was also found to cause higher energy losses in friction and pumping. In contrast, GCI performance showed stronger sensitivity towards EGR rate variation, suggesting that air-handling system development is critical for enabling efficient and clean low NOx GCI combustion. To better utilize gasoline’s lower reactivity, an analysis-led variable valve actuation investigation was performed at 15.7 GCR and 1375 rpm/10 bar BMEP. The analysis was focused on using an early intake valve closing (EIVC) approach by carrying out closed-cycle, 3-D CFD combustion simulations coupled with 1-D engine cycle analysis. EIVC was shown to be an effective means to lengthen ignition delay and promote partially-premixed combustion by lowering the engine effective compression ratio (ECR). By combining EIVC with a tailored fuel injection strategy and properly developed thermal boundary conditions, simulation predicted a 2.3% improvement in ISFC and 47% soot reduction over the baseline IVC case while keeping NOx below the baseline level.

Full-Load HCCI Operation with Variable Valve Actuation System in a Heavy-Duty Diesel Engine

2007 ◽  
Author(s):  
Yuuichi Kodama ◽  
Izumi Nishizawa ◽  
Takumi Sugihara ◽  
Norihiko Sato ◽  
Tadashi Iijima ◽  
...  
Keyword(s):  
Diesel Engine ◽  
Heavy Duty ◽  
Full Load ◽  
Variable Valve Actuation ◽  
Actuation System ◽  
Heavy Duty Diesel Engine ◽  
Heavy Duty Diesel ◽  
Variable Valve ◽  
Valve Actuation

scholarly journals Effects of multiple injections on combustion and emissions in a heavy-duty diesel engine at high load and low speed

2020 ◽  
Vol 12 (12) ◽  
pp. 168781402098462
Author(s):  
Yingying Lu ◽  
Yize Liu
Keyword(s):  
Diesel Engine ◽  
Single Injection ◽  
High Load ◽  
Post Injection ◽  
Heavy Duty ◽  
Low Speed ◽  
Multiple Injections ◽  
Heavy Duty Diesel Engine ◽  
Main Injection ◽  
Heavy Duty Diesel

Advanced multiple injection strategies have been suggested for compression ignition engines in order to meet the increasingly stringent emission regulations. Experiments and simulations were used to study effects of the main-injection mode (times), the post-injection proportion, and timing on combustion and emissions in a heavy-duty diesel engine at high load and constant low speed. The results reveal the following. The NOx emissions of 1main+1post, 2main+1post, and 3main+1post injections are all lower than those of single injection; the higher the number of main-injection pluses, the lower the NOx emissions. Enough main-post injection interval is needed to ensure post and main injections are relatively independent to entrain more fresh air to decrease the soot. Over-retarded post-injection timing tends to increase the soot due to the lower in-cylinder temperature. The combined effects of formation and oxidation determine the final soot. To gain the best trade-off of NOx and soot, compared with single injection, for the three multiple injections, the lowest soot emissions are gained at post-injection proportions of 15% and post-injection timings of 25°, 30°, and 35° CA ATDC, with soot reductions of 26.7%, −34.5%, and −112.8%, and NOx reductions of 5.88%, 21.2%, and 40.3%, respectively, for 1main+1post, 2main+1post, and 3main+1post injections.

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