Strategies for Achieving Residual-Effected Homogeneous Charge Compression Ignition Using Variable Valve Actuation

2005 ◽  
Author(s):  
P. A. Caton ◽  
H. H. Song ◽  
N. B. Kaahaaina ◽  
C. F. Edwards
Keyword(s):  
Homogeneous Charge Compression Ignition ◽  
Compression Ignition ◽  
Variable Valve Actuation ◽  
Variable Valve ◽  
Homogeneous Charge ◽  
Valve Actuation

A physics-based approach to the control of homogeneous charge compression ignition engines with variable valve actuation

2005 ◽  
Vol 6 (4) ◽  
pp. 361-375 ◽  
Author(s):  
G M Shaver ◽  
M J Roelle ◽  
P A Caton ◽  
N B Kaahaaina ◽  
N Ravi ◽  
...  
Keyword(s):  
Internal Combustion Engines ◽  
Homogeneous Charge Compression Ignition ◽  
Control Strategies ◽  
Combustion Process ◽  
System Control ◽  
Compression Ignition ◽  
Variable Valve Actuation ◽  
Variable Valve ◽  
Homogeneous Charge ◽  
Valve Actuation

Homogeneous charge compression ignition (HCCI) is a promising low-temperature combustion strategy for reducing NOx emissions and increasing efficiency in internal combustion engines. However, HCCI has no direct combustion initiator and, when achieved by reinducting or trapping residual exhaust gas with a variable valve actuation (VVA) system, becomes a dynamic process as the temperature of the residual gas couples one cycle to the next. These characteristics of residual-affected HCCI present a challenge for control engineers and a barrier to implementing HCCI in a production engine. In order to address these challenges, this paper outlines physics-based control strategies for both the VVA system and the HCCI combustion process. The results show that VVA system control can provide arbitrary valve timings on a cycle-to-cycle basis, enabling tight control of HCCI. By abstracting these valve timings further into an inducted gas composition and an effective compression ratio, model-based controllers can be developed to control simultaneously load and combustion timing in an HCCI engine.

Dynamic Modeling of Residual-Affected Homogeneous Charge Compression Ignition Engines with Variable Valve Actuation

2004 ◽  
Vol 127 (3) ◽  
pp. 374-381 ◽  
Author(s):  
Gregory M. Shaver ◽  
J. Christian Gerdes ◽  
Matthew J. Roelle ◽  
Patrick A. Caton ◽  
Christopher F. Edwards
Keyword(s):  
Internal Combustion Engines ◽  
Homogeneous Charge Compression Ignition ◽  
Control Volume ◽  
Practical Method ◽  
Ignition Process ◽  
Compression Ignition ◽  
Propane Combustion ◽  
Variable Valve Actuation ◽  
Variable Valve ◽  
Homogeneous Charge

One practical method for achieving homogeneous charge compression ignition (HCCI) in internal combustion engines is to modulate the valves to trap or reinduct exhaust gases, increasing the energy of the charge, and enabling autoignition. Controlling combustion phasing with valve modulation can be challenging, however, since any controller must operate through the chemical kinetics of HCCI and account for the cycle-to-cycle dynamics arising from the retained exhaust gas. This paper presents a simple model of the overall HCCI process that captures these fundamental aspects. The model uses an integrated Arrhenius rate expression to capture the importance of species concentrations and temperature on the ignition process and predict the start of combustion. The cycle-to-cycle dynamics, in turn, develop through mass exchange between a control volume representing the cylinder and a control mass modeling the exhaust manifold. Despite its simplicity, the model predicts combustion phasing, pressure evolution and work output for propane combustion experiments at levels of fidelity comparable to more complex representations. Transient responses to valve timing changes are also captured and, with minor modification, the model can, in principle, be extended to handle a variety of fuels.

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.

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