New gasoline homogeneous charge compression ignition combustion system using two-state direct injection and assisted spark ignition

Author(s):  
Z Wang ◽  
J-X Wang ◽  
S-J Shuai ◽  
Q-J Ma
Author(s):  
Xiaojian Yang ◽  
Guoming G Zhu

To implement the homogeneous charge compression ignition combustion mode in a spark ignition engine, it is necessary to have smooth mode transition between the spark ignition and homogeneous charge compression ignition combustions. The spark ignition–homogeneous charge compression ignition hybrid combustion mode modeled in this paper describes the combustion mode that starts with the spark ignition combustion and ends with the homogeneous charge compression ignition combustion. The main motivation of studying the hybrid combustion mode is that the percentage of the homogeneous charge compression ignition combustion is a good parameter for combustion mode transition control when the hybrid combustion mode is used during the transition. This paper presents a control oriented model of the spark ignition–homogeneous charge compression ignition hybrid combustion mode, where the spark ignition combustion phase is modeled under the two-zone assumption and the homogeneous charge compression ignition combustion phase under the one-zone assumption. Note that the spark ignition and homogeneous charge compression ignition combustions are special cases in this combustion model. The developed model is capable of simulating engine combustion over the entire operating range, and it was implemented in a real-time hardware-in-the-loop simulation environment. The simulation results were compared with those of the corresponding GT-Power model, and good correlations were found for both spark ignition and homogeneous charge compression ignition combustions.


Author(s):  
G Tian ◽  
Z Wang ◽  
Q Ge ◽  
J Wang ◽  
S Shuai

The hybrid combustion mode is an ideal operation strategy for a gasoline homogeneous charge compression ignition (HCCI) engine. A stable and smooth spark ignition (SI)/HCCI switch has been an issue in the research on multimode combustion. In this paper, the switch process has two key issues; the cam profile and throttle opening. With the developed two-stage cam system, the valve phase strategy can be switched within one engine cycle, from the normal cam profile for the SI mode to a negative valve overlap (NVO) profile for the HCCI mode, or vice versa. For a smoother and more stable switch, the throttle change was separated from the cam profile switch, which was called the stepped switch. The effect of throttle opening on HCCI combustion was studied, and the results showed that the concept of the stepped switch was reliable. With gasoline direct injection (GDI) the combustion mode switches from both SI and HCCI sides were smooth, rapid, and robust, without any abnormal combustion such as knocking and misfiring.


2018 ◽  
Vol 20 (3) ◽  
pp. 304-326 ◽  
Author(s):  
Elliott A Ortiz-Soto ◽  
George A Lavoie ◽  
Margaret S Wooldridge ◽  
Dennis N Assanis

Advanced combustion strategies for gasoline engines employing highly dilute and low-temperature combustion modes, such as homogeneous charge compression ignition and spark-assisted compression ignition, promise significant improvements in efficiency and emissions. This article presents a novel, reduced-order, physics-based model to capture advanced multi-mode combustion involving spark ignition, homogeneous charge compression ignition and spark-assisted compression ignition operating strategies. The purpose of such a model, which until now was unavailable, was to enhance existing capabilities of engine system simulations and facilitate large-scale parametric studies related to these advanced combustion modes. The model assumes two distinct thermodynamic zones divided by an infinitely thin flame interface, where turbulent flame propagation is captured using a new zero-dimensional formulation of the coherent flame model, and end-gas auto-ignition is simulated using a hybrid approach employing chemical kinetics and a semi-empirical burn rate model. The integrated model was calibrated using three distinct experimental data sets for spark ignition, homogeneous charge compression ignition and spark-assisted compression ignition combustion. The results demonstrated overall good trend-wise agreement with the experimental data, including the ability to replicate heat release characteristics related to flame propagation and auto-ignition during spark-assisted compression ignition combustion. The calibrated model was assessed using a large parametric study, where the predicted homogeneous charge compression ignition and spark-assisted compression ignition operating regions at naturally aspirated conditions were representative of those determined during engine testing. Practical advanced combustion strategies were assessed relative to idealized engine simulations, which showed that efficiency improvements up to 30% compared with conventional spark-ignition operation are possible. The study revealed that poor combustion efficiency and pumping work are the primary mechanisms for efficiency losses for the advanced combustion strategies evaluated.


2016 ◽  
Vol 18 (7) ◽  
pp. 657-676 ◽  
Author(s):  
Prasad S Shingne ◽  
Robert J Middleton ◽  
Dennis N Assanis ◽  
Claus Borgnakke ◽  
Jason B Martz

This two-part article presents a model for boosted and moderately stratified homogeneous charge compression ignition combustion for use in thermodynamic engine cycle simulations. The model consists of two components: one an ignition model for the prediction of auto-ignition onset and the other an empirical combustion rate model. This article focuses on the development and validation of the homogeneous charge compression ignition model for use under a broad range of operating conditions. Using computational fluid dynamics simulations of the negative valve overlap valve events typical of homogeneous charge compression ignition operation, it is shown that there is no noticeable reaction progress from low-temperature heat release, and that ignition is within the high-temperature regime ( T > 1000 K), starting within the highest temperature cells of the computational fluid dynamics domain. Additional parametric sweeps from the computational fluid dynamics simulations, including sweeps of speed, load, intake manifold pressures and temperature, dilution level and valve and direct injection timings, showed that the assumption of a homogeneous charge (equivalence ratio and residuals) is appropriate for ignition modelling under the conditions studied, considering the strong sensitivity of ignition timing to temperature and its weak compositional dependence. Use of the adiabatic core temperature predicted from the adiabatic core model resulted in temperatures within ±1% of the peak temperatures of the computational fluid dynamics domain near the time of ignition. Thus, the adiabatic core temperature can be used within an auto-ignition integral as a simple and effective method for estimating the onset of homogeneous charge compression ignition auto-ignition. The ignition model is then validated with an experimental 92.6 anti-knock index gasoline-fuelled homogeneous charge compression ignition dataset consisting of 290 data points covering a wide range of operating conditions. The tuned ignition model predictions of [Formula: see text] have a root mean square error of 1.7° crank angle and R2 = 0.63 compared to the experiments.


2006 ◽  
Vol 129 (4) ◽  
pp. 1079-1087 ◽  
Author(s):  
Zhi Wang ◽  
Jian-Xin Wang ◽  
Shi-Jin Shuai ◽  
Yan-Jun Wang ◽  
Guo-Hong Tian ◽  
...  

In this paper, a multimode combustion system was developed in a gasoline direct injection engine. A two-stage fuel-injection strategy, including flexible injection timings and flexible fuel quantity, is adopted as a main means to form desired mixture in the cylinder. The combustion system can realize five combustion modes. The homogeneous charge spark ignition (HCSI) mode was used at high load to achieve high-power output density; stratified charge spark ignition (SCSI) was adopted at intermediate load to get optimum fuel economy; stratified charge compression ignition (SCCI) was introduced at transient operation between SI and CI mode. Homogeneous charge compression ignition (HCCI) was utilized at part load to obtain ultralow emissions. Reformed charge compression ignition (RCCI) was imposed at low load to extend the HCCI operation range. In SI mode, the stratified concentration is formed by introducing a second fuel injection in the compression stroke. This kind of stratified mixture has a faster heat release than the homogeneous mixture and is primarily optimized to reduce the fuel consumption. In CI mode, the cam phase configurations are switched from positive valve overlap to negative valve overlap (NVO). The test results reveal that the CI combustion is featured with a high gradient pressure after ignition and has advantages in high thermal efficiency and low NOx emissions over SI combustion at part load.


2016 ◽  
Vol 18 (7) ◽  
pp. 677-700
Author(s):  
Prasad S Shingne ◽  
Jeff Sterniak ◽  
Dennis N Assanis ◽  
Claus Borgnakke ◽  
Jason B Martz

This two-part article presents a combustion model for boosted and moderately stratified homogeneous charge compression ignition combustion for use in thermodynamic engine cycle simulations. The model consists of two parts: one an ignition model for the prediction of auto-ignition onset and the other an empirical combustion rate model. This article focuses on the development of the combustion model which is algebraic in form and is based on the key physical variables affecting the combustion process. The model is fit with experimental data collected from 290 discrete automotive homogeneous charge compression ignition operating conditions with moderate stratification resulting from both the direct injection and negative valve overlap valve events. Both the ignition model from part 1 and the combustion model from this article are implemented in GT-Power and validated against experimental homogeneous charge compression ignition data under steady-state and transient conditions. The ignition and combustion model are then exercised to identify the dominant variables affecting the homogeneous charge compression ignition and combustion processes. Sensitivity analysis reveals that ignition timing is primarily a function of the charge temperature, and that combustion duration is largely a function of ignition timing.


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