Enabling Air-Path Systems for Homogeneous Charge Compression Ignition (HCCI) Engine Transient Control

2009 ◽  
Author(s):  
Fengjun Yan ◽  
Junmin Wang
Keyword(s):  
Cost Effective ◽  
Combustion Model ◽  
Gas Temperature ◽  
Independent Control ◽  
Variable Geometry Turbocharger ◽  
Hcci Engine ◽  
Engine Simulation ◽  
Hcci Combustion ◽  
Transient Control ◽  
Path System

This paper explores the possibility of using a cost-effective air-path system that includes a dual-loop (exhaust gas recirculation) EGR and a (variable geometry turbocharger) VGT to achieve independent control of the main in-cylinder charge conditions (i.e. in-cylinder oxygen, inert gas amounts, and gas temperature at the intake valve closing) for HCCI engine combustion transient operation. An engine simulation model consisting of the air-path system and a HCCI combustion model was developed and synthesized to evaluate the control authority of the air-path system on the in-cylinder charge conditions as well as their effects on combustion. A variety of simulations unveiled that such an air-path system can enable independent control of the main in-cylinder charge conditions and active compensation of the effects of the wall temperature variations on HCCI combustion.

Model-Based Estimation of Turbocharger Requirements for Boosting an HCCI Engine

2010 ◽  
Author(s):  
Sotirios Mamalis ◽  
Aristotelis Babajimopoulos
Keyword(s):  
High Pressures ◽  
Simulation Software ◽  
Exhaust Gas ◽  
University Of Michigan ◽  
Hcci Engine ◽  
Engine Simulation ◽  
Hcci Combustion ◽  
Load Limit ◽  
Intake Pressure ◽  
The University

Turbocharged Homogeneous Charge Compression Ignition (HCCI) has been modeled and has demonstrated the potential to extend the engine’s upper load limit. A commercially available engine simulation software (GT-Power®) coupled to the University of Michigan HCCI combustion and heat transfer correlations was used to model a single cylinder boosted HCCI engine including a phenomenological turbocharger model. The scope of this study is to explore the upper load limits of boosted HCCI operation and to identify turbocharger requirements for boosting the HCCI. The results of this study are consistent with the literature: Boosting helps increase the HCCI upper load limit, but matching of turbochargers is a problem. In addition, the low exhaust gas enthalpy resulting from HCCI combustion leads to high pressures in the exhaust manifold and increased pumping work. It is shown that loads as high as 17 bar NMEP can be reached at low engine speeds, when the intake pressure is 3 bar.

Model-Based Assessment of Two Variable CAM Timing Strategies for HCCI Engines: Recompression vs. Rebreathing

2009 ◽  
Author(s):  
Aristotelis Babajimopoulos ◽  
V. S. S. Prasad Challa ◽  
George A. Lavoie ◽  
Dennis N. Assanis
Keyword(s):  
Simulation Software ◽  
Combustion Model ◽  
Engine Simulation ◽  
Engine Model ◽  
Model Based ◽  
Hcci Combustion ◽  
All Speeds ◽  
Operational Range ◽  
Timing Strategies ◽  
Variable Cam Timing

The paper discusses the development and application of a single-cylinder HCCI engine model within the framework of a 1-D engine simulation software (GT-Power®). The HCCI combustion model includes a predictive burn model based on the in-cylinder conditions, along with methods to estimate in-cylinder NOx production and ringing intensity. The validation of the model was done by comparing simulation results with available experimental data, highlighting the comparison between two different HCCI variable cam timing strategies (recompression and rebreathing). A comparative study of the two valve strategies was carried out with the validated model and the entire operational range of the strategies was compared and analyzed for the constraints that limit further load extension. Recompression was found to be more efficient than rebreathing in the low load operating region. However, the rebreathing strategy was found to span a wider operational range compared to recompression at all speeds.

Calculation of Two-Phase Flow in Gas Turbine Combustors

1995 ◽  
Vol 117 (4) ◽  
pp. 695-703 ◽  
Author(s):  
A. K. Tolpadi
Keyword(s):  
Gas Turbine ◽  
Gas Phase ◽  
High Power ◽  
Liquid Droplet ◽  
Frame Of Reference ◽  
Curvilinear Coordinates ◽  
Combustion Model ◽  
Gas Temperature ◽  
Two Phase ◽  
Phase Calculation

A method is presented for computing steady two-phase turbulent combusting flow in a gas turbine combustor. The gas phase equations are solved in an Eulerian frame of reference. The two-phase calculations are performed by using a liquid droplet spray combustion model and treating the motion of the evaporating fuel droplets in a Lagrangian frame of reference. The numerical algorithm employs nonorthogonal curvilinear coordinates, a multigrid iterative solution procedure, the standard k-ε turbulence model, and a combustion model comprising an assumed shape probability density function and the conserved scalar formulation. The trajectory computation of the fuel provides the source terms for all the gas phase equations. This two-phase model was applied to a real piece of combustion hardware in the form of a modern GE/SNECMA single annular CFM56 turbofan engine combustor. For the purposes of comparison, calculations were also performed by treating the fuel as a single gaseous phase. The effect on the solution of two extreme situations of the fuel as a gas and initially as a liquid was examined. The distribution of the velocity field and the conserved scalar within the combustor, as well as the distribution of the temperature field in the reaction zone and in the exhaust, were all predicted with the combustor operating both at high-power and low-power (ground idle) conditions. The calculated exit gas temperature was compared with test rig measurements. Under both low and high-power conditions, the temperature appeared to show an improved agreement with the measured data when the calculations were performed with the spray model as compared to a single-phase calculation.

A Control Oriented SI and HCCI Hybrid Combustion Model for Internal Combustion Engines

2010 ◽  
Author(s):  
Xiaojian Yang ◽  
Guoming G. Zhu ◽  
Zongxuan Sun
Keyword(s):  
Steady State ◽  
Internal Combustion Engines ◽  
Combustion Engine ◽  
Fuel Efficiency ◽  
Combustion Process ◽  
Internal Combustion ◽  
Mean Value ◽  
Combustion Model ◽  
Zone Model ◽  
Transient Control

The combustion mode transition between SI (spark ignited) and HCCI (Homogeneously Charged Compression Ignition) of an IC (Internal Combustion) engine is challenge due to the thermo inertia of residue gas; and model-based control becomes a necessity. This paper presents a control oriented two-zone model to describe the hybrid combustion that starts with SI combustion and ends with HCCI combustion. The gas respiration dynamics were modeled using mean-value approach and the combustion process was modeled using crank resolved method. The developed model was validated in an HIL (Hardware-In-the-Loop) simulation environment for both steady-state and transient operations in SI, HCCI, and SI-HCCI hybrid combustion modes through the exhaust valve timing control (recompression). Furthermore, cooled external EGR (exhaust gas re-circulation) was used to suppress engine knock and enhance the fuel efficiency. The simulation results also illustrates that the transient control parameters of hybrid combustion is quite different from these in steady state operation, indicating the need of a control oriented SI-HCCI hybrid combustion model for transient combustion control.

Computational Analysis of an Early Direct Injected HCCI Engine with Turbocharger Using Bio Ethanol and Diesel Blends

2015 ◽  
Vol 812 ◽  
pp. 70-78
Author(s):  
S. Natarajan ◽  
A.U. Meeanakshi Sundareswaran ◽  
S. Arun Kumar ◽  
N.V. Mahalakshmi
Keyword(s):  
Chemical Kinetics ◽  
Computational Analysis ◽  
Reaction Path ◽  
Chemical Species ◽  
Operating Conditions ◽  
Injection Time ◽  
Engine Operation ◽  
Hcci Engine ◽  
Hcci Combustion ◽  
Auto Ignition

In this paper the work deals with the computational analysis of early direct injected HCCI engine with turbocharger using the CHEMKIN-PRO software. The computational analysis was carried out in the base of auto ignition chemistry by means of reduced chemical kinetics. For this study the neat diesel and Bio ethanol diesel blend (E20) were used as fuel. The inlet pressure was increased to 1.2 bar to simulate the turbocharged engine operation. The injection time was advanced to 18° before top dead centre (BTDC) i.e., 5° BTDC than normal injection time of 23° BTDC. The equivalence ratio was kept at 0.6 (ɸ=0.6) and the combustion, emission characteristics and chemical kinetics of the combustion reaction were studied. Since pressure and temperature profiles plays a very important role in reaction path at certain operating conditions, an attempt had been made here to present a complete reaction path investigation on the formation/destruction of chemical species at peak temperature and pressure conditions. The result showed that main draw backs of HCCI combustion like higher levels of unburned hydrocarbon emissions and carbon monoxide emissions are reduced in the turbocharged operation of the HCCI engine when compared to normal HCCI engine operation without turbocharger.

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