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Hua Zhao - One of the best experts on this subject based on the ideXlab platform.

  • The comparison between traditional spark ignition and micro flame ignition in gasoline high dilution combustion
    Proceedings of the Institution of Mechanical Engineers Part D: Journal of Automobile Engineering, 2021
    Co-Authors: Yifang Feng, Hui Xie, Tao Chen, Xinyan Wang, Hua Zhao
    Abstract:

    Gasoline spark ignition (SI) – Controlled Auto-Ignition (CAI) hybrid combustion had previously been shown to expanding the operational range of high-efficiency low-temperature combustion and reduci...

  • Control and optimization of spark ignition–Controlled Auto-Ignition hybrid combustion based on stratified flame ignition:
    Proceedings of the Institution of Mechanical Engineers Part D: Journal of Automobile Engineering, 2018
    Co-Authors: Tao Chen, Hua Zhao, Xinyan Wang, Bang-quan He
    Abstract:

    Spark ignition–Controlled Auto-Ignition hybrid combustion, also known as spark assisted compression ignition, is of considerable interest in gasoline engines because of its potential to enlarge the...

  • Investigations into the Influence of Dimethyl Ether Micro Flame Ignition on the Combustion and Cyclic Variation Characteristics of Flame Propagation/Auto-Ignition Hybrid Combustion in an Optical Engine
    Combustion Science and Technology, 2016
    Co-Authors: Hui Xie, Tao Chen, Hua Zhao
    Abstract:

    ABSTRACTIn order to enhance combustion phasing control and reduce cyclic variations in flame propagation/Auto-Ignition hybrid combustion, a concept of dimethyl ether (DME) micro flame ignition (MFI) hybrid combustion is proposed and studied in an optical engine. Three-stage heat release characteristics can be observed in its main combustion period, which are the rapid but short DME Auto-Ignition in the first stage, followed by slower flame propagation observed from the outer rim of the DME Auto-Ignition zone, and, at last, the intense heat release of the end-gas Auto-Ignition. The DME injection timing can be used to effectively control the combustion phasing and the early stage heat release characteristics. Compared to the spark ignition-Controlled Auto-Ignition (SI-CAI) hybrid combustion, the DME MFI hybrid combustion shows great benefits in stabilizing combustion, which is caused by the accelerated flame formation and propagation speed due to larger area of ignition source and higher ignition energy.

  • Effects of ethanol on combustion and emissions of a gasoline engine operating with different combustion modes
    International Journal of Engine Research, 2016
    Co-Authors: Mohammed Moore Ojapah, Hua Zhao, Yan Zhang
    Abstract:

    The introduction of fuel economy and CO2 emission legislations for passenger cars in many countries and regions has spurred the research and development of more efficient gasoline engines. The pumping loss at part-load operations is a major factor for the higher fuel consumption of spark-ignition gasoline engines than the diesel engines. Various approaches have been identified to reduce the pumping loss at part-load operations, leading to improved fuel economy, including early intake-valve closing, positive valve overlap and Controlled Auto-Ignition combustion. On the other hand, in order to reduce the CO2 emissions from the fossil fuel, ethanol produced from renewable resources is becoming widely used in the gasoline engine. In this article, the performance, combustion and emissions were measured, analysed and compared between gasoline and its mixture with ethanol (E15 and E85) at a typical part-load condition when a direct-injection gasoline engine was operated with the Controlled Auto-Ignition combusti...

  • a study of combining gasoline engine downsizing and Controlled auto ignition combustion
    Journal of KONES, 2015
    Co-Authors: Ben G Moxey, Alasdair Cairns, A Ganippa, Hua Zhao, M Bassett
    Abstract:

    In recent years European automotive CO 2 emissions targets have largely been met through increased diesel sales. However, the distillation of crude oil results in high proportions of both gasoline and diesel fuel and ultimately this has resulted in Europe being “diesel lean” at times. In order to meet future global emissions goals, in the short term it will be necessary to improve the fuel consumption of the gasoline engine and in the longer term source sustainable alternatives to crude oil. The objective of the current work was to investigate the optimum trade-off between the opposing engine operating requirements of gasoline engine downsizing and Controlled Auto-Ignition (CAI) combustion for use in a family-sized passenger car. Experimental fuel consumption and emissions data were produced for four sizes of spark ignition engine, varying from 1 to 2 litres in capacity. The additional benefits of two experimentally developed CAI operating methodologies were evaluated in each engine using drive cycle simulation software. The first CAI mode was based on novel use of combined internal and external EGR to attain higher loads. The second involved the adoption of turbocharging at part-load for yet higher output via so-called lean-boosted CAI. It was concluded that, for such a vehicle, a compromise exists where best fuel economy can be obtained from a moderately downsized CAI-capable engine. Compared to the baseline 2 litre engine, it was possible to obtain fuel economy benefit equivalent to that offered from an aggressively downsized 1 litre unit but using a moderately downsized 1.4 litre CAI engine, without the need for any complex boosted operation or expensive emissions aftertreatment systems. As capacity was reduced below 1.4 litres, the benefit of CAI diminished at an accelerated rate due to progressive failure to capture key higher load sites visited across the European drive cycle.

Rui Chen - One of the best experts on this subject based on the ideXlab platform.

  • Validation of in-cylinder flow of a Controlled Auto-Ignition engine
    World Journal of Engineering, 2014
    Co-Authors: Julien A. Beauquel, Salah Ibrahim, Rui Chen
    Abstract:

    Numerical calculations have been carried out to investigate the in-cylinder transient flow structure of a Controlled Auto-Ignition (CAI) engine running at speeds of 1500 rpm and 2000 rpm. The calculated turbulent flow structure and velocities are validated against published laser doppler anemometry (LDA) experimental data (Pitcher et al., 2003). The experimental data was reprocessed to represent the time dependent mean velocities for all measured points. The actual geometry configuration of the engine is imported into the computational fluid dynamics (CFD) code used in this study. The simulations take into account the movement of the inlet, exhaust valves and the piston. The CFD simulations replicate the experimental work where only air was inserted into a driven optical engine. Also, to simulate an engine in Controlled Auto-Ignition (CAI) mode, the same valve timing that allows 36% internal exhaust gas recirculation (IEGR) was applied for the air intake. The calculated results found to agree well with th...

  • Calculations of in-cylinder flow of a Controlled Auto-Ignition (CAI) engine
    World Journal of Engineering, 2014
    Co-Authors: Julien A. Beauquel, Salah Ibrahim, Rui Chen
    Abstract:

    After validation of the numerical model against published laser doppler anemometry (LDA) experimental data (Pitcher et al., 2003), numerical calculations have been carried out to investigate the in-cylinder transient flow structure of a Controlled Auto-Ignition (CAI) engine running at speeds of 1,500 rpm and 2,000 rpm. The geometry configuration of the engine is imported into the computational fluid dynamics (CFD) code used in this study. The simulations take into account the movement of the inlet, exhaust valves and the piston. To simulate an engine in Controlled Auto-Ignition (CAI) mode, the same valve timing that allows 36% gas residuals was applied to the model. The evolution of the flow pattern inside the cylinder at the symmetrical cross section is described. Also, the turbulence intensity (TI), the turbulent kinetic energy (TKE) and turbulent dissipation rate (TDR) are described for a better understanding of the effect of engine speed on the turbulences generated. The effects of engine speed on fresh charge velocity are also revealed.

  • Validation of in-cylinder flow structure of Controlled Auto-Ignition engine
    World Journal of Engineering, 2013
    Co-Authors: Julien A. Beauquel, Salah Ibrahim, Rui Chen
    Abstract:

    Numerical calculations have been carried out to investigate the in-cylinder transient flow structure of a Controlled Auto-Ignition (CAI) engine running at speeds of 1,500rpm and 2,000rpm. The calculated turbulent flow structure and velocities are validated against published laser doppler anemometry (LDA) experimental data. The experimental data were re-processed to represent the time dependent mean velocities for all measured points. The actual geometry configuration of the engine is imported into the computational fluid dynamics (CFD) code used in this study. The simulations take into account the movement of the inlet, exhaust valves and the piston. The CFD simulations replicate the experimental work where only air was inserted into a driven optical engine. Also, to simulate an engine in Controlled Auto-Ignition (CAI) mode, the same valve timing that allows 36% internal exhaust gas recirculation (IEGR) was applied for the air intake. The calculated results are found to agree well with the LDA measurement...

  • Multi-Zone Kinetic Model of Controlled Auto Ignition Combustion
    SAE Technical Paper Series, 2009
    Co-Authors: Rui Chen, Zhen Liu
    Abstract:

    A multi-zone Controlled Auto Ignition (CAI) model for simulating the combustion and emissions has been developed and reported in this paper. The model takes into account the effects of the boundary layer, crevice volume, and blowby. In order to investigate the influences of in-cylinder inhomogeneity, the main cylinder chamber has been divided into multiple core zones with varying temperature and composition. Mass and energy transfer between neighbouring zones were modeled. A reduced chemical kinetic mechanism was implemented in each zone to simulate the CAI combustion chemistry and emission formation. An in-house code, the LUCKS (Loughborough University Chemical Kinetics Simulation), was employed to solve the coupled differential equations of the system. The model was validated against experimental results at various Internal Exhaust Gas Recirculation (IEGR) levels and was then used to analyze the thermal and chemical effect of the IEGR on the CAI combustion. Good agreement between modeling and experimental results in terms of major CAI combustion parameters and emissions (CO, HC, and NOx) has been achieved.

  • Computational study on the charge mixing of internal exhaust gas recirculation initiated Controlled auto ignition
    2004
    Co-Authors: Paul Osei-owusu, Rui Chen, Salah Ibrahim
    Abstract:

    Controlled Auto Ignition (CAI) uses compression heat to auto ignite a homogeneous air/fuel mixture. Using internal exhaust gas re-circulation (IEGR) as an indirect control method, CAI offers potentially superior fuel economy and pollutant emission reductions. The local chemical and thermal conditions of the engine charge towards the end of the compression stroke have significant influences toward fuel auto ignition performance. In this study, KIVA-3V has been employed to investigate the mixing process involving the fuel, air and the IEGR inside a pentroof engine. The calculated results were compared with experimental data. A mixing index was formulated to show the level of homogeneity in the mixture during the compression process. Good correlations were obtained between the measured and calculated data. Results showed that the level of mixing between trapped burnt gas and the fresh mixture is enhanced by increasing the percentage of trapped IEGR.

Zhao Hua - One of the best experts on this subject based on the ideXlab platform.

  • In-Cylinder Gas Sampling of Aldehydes in a Controlled Auto-Ignition Engine Fueled by High Octane Number Fuels
    Transactions of Csice, 2012
    Co-Authors: Zhao Hua
    Abstract:

    With DNPH derivative method,high performance liquid chromatography(HPLC)technology and in-cylinder gas sampling system modified from a gasoline direct injection injector in a Ricardo Hydra 4-stroke single cylinder gasoline engine,the in-cylinder gas sampling experiments were conducted to study the aldehydes concentration histories during the low-temperature oxidation process of high-octane fuels(methanol and gasoline).Experimental results show that a certain of formaldehyde and acetaldehyde,and a small amount of propionaldehyde,butyraldehyde and isovaleraldehyde are existed in the incylinder hot residual gas when fueled with methanol and gasoline.During the compression process,formaldehyde and acetaldehyde show a decreasing and then increasing trend,and this indicates that these substances are consumed through low-temperature reactions to promote the oxidation of fuel and then produced during the main oxidation process of fuel.Under the same operation condition,formaldehyde concentration in the residual gas of methanol is higher than that of gasoline because of different reaction mechanism.This may be one of the reasons that the ignition timing is earlier in compression combustion of methanol than gasoline.

  • In-Cylinder Gas Sampling and Detection Analysis Methods of Methanol Fueled Controlled Auto-Ignition Engines
    Journal of Tianjin University, 2012
    Co-Authors: Zhao Hua
    Abstract:

    In order to study the components of chemical substances in the hot residual gas and their effects on low-temperature oxidation process of methanol in a homogenous charge compression ignition engine,an in-cylinder gas sampling system and an aldehydes/ketones testing method were developed according to EPA standard by modifying a GDI injector on a Ricardo Hydra 4-stroke single cylinder gasoline engine.The in-cylinder sampling experiments dur-ing the methanol low-temperature combustion process were carried out.Aldehydes/ketones were collected with DNPH-silica cartridge and then analyzed qualitatively and quantitatively by high-performance liquid chromatography(HPLC).The sampling and analysis methods were studied by penetrability experiment,elution rate experiment and standard curve performance.And the results showed that there are formaldehyde,acetaldehyde,acetone,propylene ketone,etc,in the hot residual gas,which have some influence on the low-temperature oxidation of methanol.

  • Control of Spark Assisted Controlled Auto Ignition Hybrid Combustion Process
    Journal of Combustion Science and Technology, 2009
    Co-Authors: Zhao Hua
    Abstract:

    To solve such problems as control of ignition timing,narrow operating range and combustion mode change,which exist in the application of CAI combustion in a gasoline engine,spark-assisted CAI hybrid combustion mode were applied around high and low load boundaries.With spark assisted CAI hybrid combustion,deflagration with high load limit and instability with low load limit were avoided because of flexible control of ignition timing and combustion phase,resulting in the extension of operation range of the CAI engine.Ignition timing,residual gas fraction and effective compression ratio have great influence on spark-assisted CAI hybrid combustion process.With the rapid management of residual gas,the inflexion position in the hybrid heat release process is under control,so is the proportion of SI and CAI combustion.

  • Experimental Study on CAI Gasoline Engine Equipped with 4-Variable Valve Actuating System
    Transactions of Csice, 2007
    Co-Authors: Zhao Hua
    Abstract:

    Controlled Auto-Ignition combustion was achieved using negative valve overlap method to trap enough hot residual gas to heat mixture in a PFI gasoline engine equipped with a 4-variable valve actuating system(4VVAS).The effects of the valve parameters on the gasoline Controlled Auto-Ignition(CAI)combustion are experimentally investigated.The results show that different load ranges can be achieved using various valve curves.The low-speed-high-load and the high-speed-high-load regions can be extended respectively through late intake valve closing with reduced effective compression ratio and high valve lifts.The exhaust valves mainly control the load,while the intake valve events can alter the effective compression ratio and back flow of intake charge.These consequently make the symmetrical control effect on the residual gas fraction and the CAI combustion process.

  • Auto-Ignition and Heat Release Correlations for Controlled Auto-Ignition Combustion in Gasoline Engines
    2007
    Co-Authors: Zhao Hua
    Abstract:

    Auto-Ignition and heat release correlations for Controlled Auto-Ignition(CAI)combustion were derived from extensive in-cylinder pressure data of a four-stroke gasoline engine operating in CAI combustion mode.Abundant experiments were carried out under a wide range of air/fuel ratio,speed and residual gas fraction to ensure that the combustion correlations can be used in the entire CAI engine operation range.Furthermore,a more accurate method to compute the residual gas fraction was proposed by calculating the working fluid temperature at the exhaust valve close timing in the experiments.The heat release correlation was described in two parts,one is for the first slower heat release process at low temperature,and the other is for the second faster heat release process at high temperature.Finally the heat release correlation was evaluated on the single cylinder gasoline engine running with CAI combustion by comparing the experimental data with the 1-D engine simulation results obtained with the aid of the GT-Power simulation program.The results show that the predicted loads and ignition timings match closely with the measurements.

Zulkarnain Abdul Latiff - One of the best experts on this subject based on the ideXlab platform.

  • experimental investigation of the influence of internal and external egr on the combustion characteristics of a Controlled auto ignition two stroke cycle engine
    Applied Energy, 2014
    Co-Authors: Amin Mahmoudzadeh Andwari, Azhar Abdul Aziz, Mohd Farid Muhamad Said, Zulkarnain Abdul Latiff
    Abstract:

    A two-stroke cycle engine incorporated with a Controlled Auto-Ignition combustion approach presents a high thermodynamic efficiency, ultra-low exhaust emissions and high power-to-weight ratio features for future demand of prime movers. The start of Auto-Ignition, control of the Auto-Ignition and its cyclic variability, are major concerns that should be addressed in the combustion timing control of Controlled Auto-Ignition engines. Several studies have been performed to examine the effect of internal exhaust gas recirculation utilization on auto-ignited two-stroke cycle engines. However, far too little attention has been devoted to study on the influence of external exhaust gas recirculation on the cyclic variation and the combustion characteristics of Controlled Auto-Ignition two-stroke cycle engines. The purpose of this study is to examine the influence of external exhaust gas recirculation in combination with internal exhaust gas recirculation on the combustion characteristics and the cyclic variability of a Controlled Auto-Ignition two-stroke engine using fuel with different octane numbers. In a detailed experimental investigation, the combustion-related and pressure-related parameters of the engine are examined and statistically associated with the coefficient of variation and the standard deviation. The outcomes of the investigation indicates that the most influential Controlled Auto-Ignition combustion phasing parameters can be managed appropriately via regulating the internal and external exhaust gas recirculation and fuel octane number. In general, start of Auto-Ignition and its cyclic variability are predominantly affected by external exhaust gas recirculation variation rather than internal exhaust gas recirculation. Furthermore, although the magnitude of low temperature heat release is substantially influenced by external exhaust gas recirculation variation, timing of low temperature heat release is more influenced by internal exhaust gas recirculation approach.

  • A Converted Two-Stroke Cycle Engine for Compression Ignition Combustion
    Applied Mechanics and Materials, 2014
    Co-Authors: Amin Mahmoudzadeh Andwari, Azhar Abdul Aziz, Mohd Farid Muhamad Said, Zulkarnain Abdul Latiff
    Abstract:

    A new kind of alternative combustion concept that has attracted attention intensively in recent years is called Controlled Auto-Ignition (CAI) combustion. CAI combustion has been proposed and partially implemented with the aim of both improving the thermal efficiency of internal combustion engines, achieving cleaner exhaust emissions and lower cyclic variation. An experimental study is conducted through a CAI two-stroke cycle engine in order to investigate the influence of internal exhaust gas recirculation (In-EGR) and external exhaust gas recirculation (Ex-EGR) variation in relation to combustion cyclic variability and exhaust emissions characteristics. Results implied that cyclic variation of both combustion-related and pressure-related parameter is substantially improved. Furthermore remarkable decreased exhaust emissions, unburned hydrocarbon (uHC), carbon monoxide (CO) and nitric dioxide (NOX), was observed.

Amin Mahmoudzadeh Andwari - One of the best experts on this subject based on the ideXlab platform.

  • influence of hot burned gas utilization on the exhaust emission characteristics of a Controlled auto ignition two stroke cycle engine
    International Journal of Automotive and Mechanical Engineering, 2015
    Co-Authors: Amin Mahmoudzadeh Andwari, Azhar Abdul Aziz, Mohd Farid Muhammad Said, Zulkanai Abdul Latiff, Ali Ghanaati
    Abstract:

    A Controlled Auto-Ignition (CAI) two-stroke cycle engine suggests an exceptional aspect and promising future for internal combustion engines (ICEs), such as a higher power-toweight ratio, higher combustion efficiency and lower exhaust gas emissions. Conventional two-stroke cycle engines emit higher exhaust gas emissions and offer lower fuel saving economy. Most of these drawbacks can be addressed if CAI combustion is associated with a two-stroke cycle engine. An experimental investigation is carried out based on a single-cylinder CAI two-stroke cycle engine using Internal and External Exhaust Gas Recirculation (In-EGR and Ex-EGR) and fuels with different octane numbers to investigate the exhaust emissions characteristics. The experimental results indicate a remarkable improvement in the engine's exhaust gas emissions. The concentration of uHC and CO emissions decreased with application of In/Ex-EGR. However, NOx emission increased with the use of In-EGR

  • experimental investigation of the influence of internal and external egr on the combustion characteristics of a Controlled auto ignition two stroke cycle engine
    Applied Energy, 2014
    Co-Authors: Amin Mahmoudzadeh Andwari, Azhar Abdul Aziz, Mohd Farid Muhamad Said, Zulkarnain Abdul Latiff
    Abstract:

    A two-stroke cycle engine incorporated with a Controlled Auto-Ignition combustion approach presents a high thermodynamic efficiency, ultra-low exhaust emissions and high power-to-weight ratio features for future demand of prime movers. The start of Auto-Ignition, control of the Auto-Ignition and its cyclic variability, are major concerns that should be addressed in the combustion timing control of Controlled Auto-Ignition engines. Several studies have been performed to examine the effect of internal exhaust gas recirculation utilization on auto-ignited two-stroke cycle engines. However, far too little attention has been devoted to study on the influence of external exhaust gas recirculation on the cyclic variation and the combustion characteristics of Controlled Auto-Ignition two-stroke cycle engines. The purpose of this study is to examine the influence of external exhaust gas recirculation in combination with internal exhaust gas recirculation on the combustion characteristics and the cyclic variability of a Controlled Auto-Ignition two-stroke engine using fuel with different octane numbers. In a detailed experimental investigation, the combustion-related and pressure-related parameters of the engine are examined and statistically associated with the coefficient of variation and the standard deviation. The outcomes of the investigation indicates that the most influential Controlled Auto-Ignition combustion phasing parameters can be managed appropriately via regulating the internal and external exhaust gas recirculation and fuel octane number. In general, start of Auto-Ignition and its cyclic variability are predominantly affected by external exhaust gas recirculation variation rather than internal exhaust gas recirculation. Furthermore, although the magnitude of low temperature heat release is substantially influenced by external exhaust gas recirculation variation, timing of low temperature heat release is more influenced by internal exhaust gas recirculation approach.

  • A Converted Two-Stroke Cycle Engine for Compression Ignition Combustion
    Applied Mechanics and Materials, 2014
    Co-Authors: Amin Mahmoudzadeh Andwari, Azhar Abdul Aziz, Mohd Farid Muhamad Said, Zulkarnain Abdul Latiff
    Abstract:

    A new kind of alternative combustion concept that has attracted attention intensively in recent years is called Controlled Auto-Ignition (CAI) combustion. CAI combustion has been proposed and partially implemented with the aim of both improving the thermal efficiency of internal combustion engines, achieving cleaner exhaust emissions and lower cyclic variation. An experimental study is conducted through a CAI two-stroke cycle engine in order to investigate the influence of internal exhaust gas recirculation (In-EGR) and external exhaust gas recirculation (Ex-EGR) variation in relation to combustion cyclic variability and exhaust emissions characteristics. Results implied that cyclic variation of both combustion-related and pressure-related parameter is substantially improved. Furthermore remarkable decreased exhaust emissions, unburned hydrocarbon (uHC), carbon monoxide (CO) and nitric dioxide (NOX), was observed.

  • Controlled Auto-Ignition Combustion in a Two-Stroke Cycle Engine Using Hot Burned Gases
    Applied Mechanics and Materials, 2013
    Co-Authors: Amin Mahmoudzadeh Andwari, Azhar Abdul Aziz, Muhamad Said Mohd Farid, Abdul Latiff Zulkarnain
    Abstract:

    A new combustion concept, which is viewed increasingly as a probable solution to these issues is Controlled Auto-Ignition (CAI) Combustion. In such an engine, a homogeneous mixture of air, fuel and residual gases is compressed until Auto-Ignition occurs. Due to its significantly low temperature combustion, NOx will be dramatically reduced while the mixture will be under ultra-lean fuel-air condition, thus able to achieve high efficiency and low emission. In the case of two-stroke engine, problem of poor combustion efficiency and excessive white smoke emission can be addressed by the incorporation some features that will ultimately convert a typical two-stroke engine into an efficient CAI engine demonstrating the best of both features. Due to its inherent high internal residual gas rate in partial load operation, the two-stroke engine has been the first application to benefit from the unconventional CAI combustion process. This paper will concisely discuss the utilization of hot burned gas for induction thus imposing a CAI combustion feature onto two-stroke cycle engine. Among the features incorporated are the increasing in the level of Exhaust gas Recirculation and cycle-by-cycle uniformity of the air-fuel ratio (AFR) supplied to cylinder, which will be crucial in creating a suitable temperature within the engine’s combustion chamber.