scholarly journals Visualization Study on Premixed Charge Compression Ignition Process of Heterogeneous Mixture

2011 ◽  
Vol 31 (120) ◽  
pp. 21
Author(s):  
Yoshimitsu Kobashi ◽  
Jiro Senda
Keyword(s):  
Ignition Process ◽  
Compression Ignition ◽  
Heterogeneous Mixture

scholarly journals Ignition Process and Flame Lift-Off Characteristics of dimethyl ether (DME) Reacting Spray

2021 ◽  
Vol 7 ◽  
Author(s):  
Khanh Duc Cung ◽  
Ahmed Abdul Moiz ◽  
Xiucheng Zhu ◽  
Seong-Young Lee
Keyword(s):  
Dimethyl Ether ◽  
Alternative Fuels ◽  
Chemical Properties ◽  
Injection Pressure ◽  
High Reactivity ◽  
Combustion Characteristic ◽  
Spray Combustion ◽  
Ignition Process ◽  
Compression Ignition ◽  
Lift Off

Advanced combustion systems that utilize different combustion modes and alternative fuels have significantly improved combustion performance and emissions compared to conventional diesel or spark-ignited combustions. As an alternative fuel, dimethyl ether (DME) has been receiving much attention as it runs effectively under low-temperature combustion (LTC) modes such as homogeneous charge compression ignition (HCCI) and reactivity control combustion ignition (RCCI). Under compression-ignition (CI), DME can be injected as liquid fuel into a hot chamber, resulting in a diesel-like spray/combustion characteristic. With its high fuel reactivity and unique chemical formula, DME ignites easily but produces almost smokeless combustion. In the current study, DME spray combustion under several different conditions of ambient temperature (Tamb = 750–1100 K), ambient density (ρamb = 14.8–30 kg/m3), oxygen concentration (O2 = 15–21%), and injection pressure (Pinj = 75–150 MPa) were studied. The results from both experiments (constant-volume combustion vessel) and numerical simulations were used to develop empirical correlations for ignition and lift-off length. Compared to diesel, the established correlation of DME shows a similar Arrhenius-type expression. Sensitivity studies show that Tamb and Pinj have a stronger effect on DME's ignition and combustion than other parameters. Finally, this study provides a simplified conceptual mechanism of DME reacting spray under high reactivity ambient (high Tamb, high O2) and LTC conditions. Finally, this paper discusses engine operating strategies using a non-conventional fuel such as DME with different reactivity and chemical properties.

A Stochastic Simulation of an HCCI Engine Using an Automatically Reduced Mechanism

2001 ◽  
Author(s):  
Hakan Serhad Soyhan ◽  
Terese Løvås ◽  
Fabian Mauss
Keyword(s):  
Flow Reactor ◽  
Plug Flow ◽  
High Sensitivity ◽  
Ignition Process ◽  
Compression Ignition ◽  
Detailed Chemical Kinetics ◽  
Promising Alternative ◽  
Hcci Engine ◽  
Reduced Mechanism ◽  
Skeletal Mechanism

Abstract Homogeneous Charge Compression Ignition (HCCI) Engines are a promising alternative to the existing Spark Ignition Engines and Compression Ignition Engines. In an HCCI engine, the premixed fuel/air mixture ignites when sufficiently high temperature and pressure is reached. The entire bulk will auto-ignite at almost the same time because the physical conditions are similar throughout the combustion chamber. Therefore it is a justified assumption to consider the chemical reactions to be the rate-determining step for the ignition process. This gives us the opportunity to formulate a simple zero-dimensional model with detailed chemical kinetics for the calculations of the ignition process. Ignition calculations using this model have predicted a high sensitivity to fluctuations in temperature and fuel compositions. These predictions have later been confirmed by experiments. Partially stirred plug flow reactor (PaSPFR) can be used to conquer the assumption of homogeneity. The assumption is replaced by that of statistical homogeneity and thus statistical fluctuations caused by inhomogeneities can be studied. However, the CPU-time needed for this approach is increased considerably and the usage of mechanism reduction becomes evident. In this paper, we demonstrate how a reduced mechanism for natural gas as fuel is derived automatically. The original mechanism by Warnatz (589 reactions, 53 species) is first reduced to a skeletal mechanism (481 reactions, 43 species). By introduction of the quasi steady state assumption, the skeletal mechanism is reduced further to 23 species and 20 global reactions. The accuracy of the final mechanism is demonstrated using the stochastic reactor tool for an HCCI engine.

1216 Modeling Premixed Compression Ignition Process

2001 ◽  
Vol 2001.76 (0) ◽  
pp. _12-31_-_12-32_
Author(s):  
Keiichiro NOJIRI ◽  
Katsuya SAIJYO ◽  
Kazuie NISHIWAKI ◽  
Yoshinobu YOSHIHARA
Keyword(s):  
Ignition Process ◽  
Compression Ignition

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.

Simulating the homogeneous charge compression ignition process using a detailed kinetic model for n-heptane mixtures

2000 ◽  
Vol 1 (3) ◽  
pp. 281-289 ◽  
Author(s):  
J Kusaka ◽  
T Yamamoto ◽  
Y Daisho
Keyword(s):  
Compression Ratio ◽  
Homogeneous Charge Compression Ignition ◽  
Combustion Model ◽  
Ignition Process ◽  
Compression Ignition ◽  
Complete Combustion ◽  
Hcci Combustion ◽  
Excess Air ◽  
Auto Ignition ◽  
Homogeneous Charge

The homogeneous charge compression ignition (HCCI) combustion has been attracting growing attention in recent years due to its potential for simultaneous improvement of exhaust gas emissions and fuel consumption in diesel engines. For practical application of HCCI to internal combustion (IC) engines, precise control of auto-ignition of pre-mixtures during the compression stroke is inevitable. This paper discusses the auto-ignition processes in an HCCI engine operated with n-heptane/air mixtures using a zero-dimensional combustion model including a detailed kinetics. The model proposed is validated first by a comparison between calculated and experimental pressure diagrams, and then the effects of initial charge conditions, compression ratio and excess air ratio on ignition and combustion are investigated. It was found from the parametric study that HCCI combustion of n-heptane/air mixtures is classified into three types of combustion: complete combustion, only low-temperature reaction and misfire, depending on the compression ratio and excess air ratio at which the engine is operated. Finally, the major paths of the HCCI reaction occurring in the engine cylinder were clarified by a sensitivity analysis of chemical reactions involved in the HCCI reaction scheme.

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