Effects of fuel injection parameters on the performance of homogeneous charge compression ignition at low-load conditions

2015 ◽  
Vol 17 (4) ◽  
pp. 413-420 ◽  
Author(s):  
SeungHwan Keum ◽  
Pinaki Pal ◽  
Hong G Im ◽  
Aristotelis Babajimopoulos ◽  
Dennis N Assanis
Keyword(s):  
Homogeneous Charge Compression Ignition ◽  
Fuel Injection ◽  
Compression Ignition ◽  
Injection Parameters ◽  
Low Load ◽  
Load Conditions ◽  
Homogeneous Charge

Experimental and Numerical Analysis on the Influences of Direct Fuel Injection into Oxygen-Depleted Environment of a Homogeneous Charge Compression Ignition Engine

2021 ◽  
pp. 1-29
Author(s):  
Ratnak Sok ◽  
Kei Yoshimura ◽  
Kenjiro Nakama ◽  
Jin Kusaka
Keyword(s):  
Homogeneous Charge Compression Ignition ◽  
Fuel Injection ◽  
Double Pulse ◽  
Gasoline Direct Injection ◽  
Oh Radicals ◽  
Compression Ignition ◽  
Compression Ignition Engine ◽  
Intake Stroke ◽  
Direct Fuel Injection ◽  
Homogeneous Charge

Abstract The oxygen-depleted environment in the recompression stroke can convert gasoline fuel into light hydrocarbons due to thermal cracking, partial oxidation, and water-gas shift reactions. These reformate species can influence the combustion characteristics of gasoline direct injection homogeneous charge compression ignition (GDI-HCCI) engines. In this work, the combustion phenomena are investigated using a single-cylinder research engine under a medium load. The main combustion phases are experimentally advanced by direct fuel injection into the negative valve overlap (NVO) compared with that of intake stroke under single/double pulse injections. NVO peak in-cylinder pressures are lower than that of motoring due to the limited O2 concentration, emphasizing that endothermic reactions occur during the overlap. This phenomenon limits the oxidation reactions, and the thermal effect is not pronounced. The 0-D chemical kinetics results present the same increasing tendencies of classical reformed species of rich-mixture such as C3H6, C2H4, CH4, CO, and H2 as functions of injection timings. Predicted ignition delays are shortened due to the additions of these reformed species. The influences of the reformates on the main combustion are confirmed by 3-D CFD calculations, and the results show that OH radicals are advanced under NVO injections relative to intake stroke injections. Consequently, earlier heat release and cylinder pressure are noticeable. Parametric studies on the effects of injection pressure, double-pulse injection, and equivalence ratio on the combustion and emissions are also discussed experimentally.

Experimental Investigation of Homogeneous Charge Compression Ignition Engine of Ethanol and Diesel Blends

2013 ◽  
Vol 440 ◽  
pp. 254-259 ◽  
Author(s):  
S. Natarajan ◽  
N.V. Mahalakshmi ◽  
S. Sundarraj
Keyword(s):  
Experimental Investigation ◽  
Homogeneous Charge Compression Ignition ◽  
Fuel Injection ◽  
Research Work ◽  
Compression Ignition ◽  
Oxides Of Nitrogen ◽  
Ignition Timing ◽  
Compression Ignition Engine ◽  
Reduction Of Oxides ◽  
Homogeneous Charge

This paper deals with the experimental investigation of a Homogeneous Charge Compression Ignition (HCCI) Engine system. The main objective of this research work is to study the effects of a premixed fuel ratio on the performance, combustion characteristics and reduction of oxides of nitrogen and smoke intensity, using the HCCI concept. The engine used for the experiments was of a Kirloskar TAF-I series. The engine is a four stroke, single cylinder air cooled diesel engine, of a rated power of 4.4 kW loaded with an electrical dynamometer. An electronic fuel injection circuit was developed to control the ignition timing and duration of the premixed charge. Ethanol was premixed, and a part injected before ignition, whereas the diesel fuel was injected by the conventional injector directly into the cylinder. The part injected ethanol and direct injected diesel were tested in various proportions, to optimize the operating range, and the same setup was tested with various % of EGR.The obtained results include data plots illustrating the performance, combustion and emission characteristics. The results indicate that the concentration of the oxides of nitrogen species rapidly decreased, and the smoke emissions were reduced simultaneously at 20% Rp and 20% EGR in 75% load and full load conditions.

Understanding chemical effects in low-load-limit extension of homogeneous charge compression ignition engines via recompression reaction

2009 ◽  
Vol 10 (4) ◽  
pp. 231-250 ◽  
Author(s):  
H H Song ◽  
C F Edwards
Keyword(s):  
Ignition Delay ◽  
Homogeneous Charge Compression Ignition ◽  
Compression Ignition ◽  
Model Calculations ◽  
Load Limit ◽  
Low Load ◽  
Fuel Pyrolysis ◽  
Recompression Reaction ◽  
Lean Conditions ◽  
Homogeneous Charge

In-cylinder pre-processing (or recompression reaction) of pilot-injected fuel during negative value overlap (NVO) has been investigated as a method to extend the low-load limit of residual-effected homogeneous charge compression ignition (HCCI). In an effort to elucidate the chemical and thermal effects involved, model calculations have been performed on the recompression reaction and ignition delay of the recompression products using a reduced n-heptane mechanism (160 reactions, 1424 reactions) and a zero-dimensional kinetics model. Parametric studies were performed to cover possible operating choices for HCCI and to understand their effects on the recompression reaction and mixture ignitability. From the study it is demonstrated that the extent of recompression reaction is limited by chemical kinetics, not thermodynamics, and that residual oxygen during NVO is a determining species for the extent and speciation of the recompression reaction. The recompression product mixture exhibits an overall shorter ignition delay than those of the base fuel, except under lean conditions when significant oxidation during NVO leaves only a small amount of fuel available for main ignition. The thermal consequence of the recompression reaction is also largely dependent on oxygen: at near-stoichiometric conditions, the recompression reaction is endothermic from fuel pyrolysis, whereas at lean conditions, the exothermic recompression reaction becomes dominant. Therefore, the chemical and thermal consequences of the recompression reaction exhibit competing effects on mixture ignitability, which leads to an optimum oxygen concentration (equivalence ratio) for reducing ignition delay and extending HCCI operability.

scholarly journals Cycle-by-cycle variations in autonomous and spark assisted homogeneous charge compression ignition combustion of stoichiometric air–fuel mixture

2018 ◽  
Vol 10 (3) ◽  
pp. 231-243 ◽  
Author(s):  
Jacek Hunicz
Keyword(s):  
Homogeneous Charge Compression Ignition ◽  
Fuel Injection ◽  
Fuel Mixture ◽  
Compression Ignition ◽  
Indicated Mean Effective Pressure ◽  
Start Of Injection ◽  
Negative Valve Overlap ◽  
Compression Ignition Combustion ◽  
Valve Overlap ◽  
Homogeneous Charge

This study investigates cycle-by-cycle variations in a gasoline fuelled, homogeneous charge compression ignition (HCCI) engine with internal exhaust gas recirculation. In order to study the effects of exhaust-fuel reactions occurring prior to the main combustion event fuel was injected directly into the cylinder at two selected timings during the negative valve overlap period. The engine was operated as both autonomous HCCI and spark assisted HCCI (SA-HCCI). The primary interest in this work was the operating region where the engine is switched between HCCI and spark ignition modes, thus operation with stoichiometric air–fuel mixture, which is typical for this region, was considered. Cycle-by-cycle variations in both combustion timing and indicated mean effective pressure (IMEP) were investigated. It was found that long-period oscillations of the IMEP occur when fuel injection is started at early stages of the negative valve overlap period, and that these can be suppressed by delaying the start of injection. This behaviour remained even when fuel injection was split into early and late-negative valve overlap injections. Spark assisted operation allowed eliminating late combustion cycles, thus improving thermal efficiency. However, characteristic patterns of IMEP variations were found to be the same for both HCCI and SA-HCCI operations, irrespective of the adopted negative valve overlap fuel injection strategy, as evidenced by using symbol-sequence statistics.

Effects of Multi-Injection Mode on Diesel Homogeneous Charge Compression Ignition Combustion

2006 ◽  
Vol 129 (1) ◽  
pp. 230-238 ◽  
Author(s):  
Wanhua Su ◽  
Bin Liu ◽  
Hui Wang ◽  
Haozhong Huang
Keyword(s):  
Thermal Efficiency ◽  
Homogeneous Charge Compression Ignition ◽  
Fuel Injection ◽  
Direct Injection ◽  
Progressive Increase ◽  
Compression Ignition ◽  
Injection Mode ◽  
Hcci Combustion ◽  
Injection Modes ◽  
Homogeneous Charge

Early injection, well before top dead center (TDC), has perhaps been the most commonly investigated approach to obtain homogeneous charge compression ignition (HCCI) combustion in a direct-injection (DI) diesel engine. However, wall wetting due to overpenetration of the fuel spray can lead to unacceptable amounts of unburned fuel and removal of lubrication oil. Another difficulty of diesel HCCI combustion is the control of combustion phasing. In order to overcome these difficulties, a multipulse fuel injection technology has been developed for the purpose of organizing diesel HCCI combustion, by which the injection width, injection number, and the dwell time between two neighboring pulse injections can be flexibly regulated. In present paper, the effects of a series of multipulse injection modes realized based on the prejudgment of combustion requirement, on engine emissions, thermal efficiency, and cycle fuel energy distribution of diesel HCCI combustion are studied. The designed injection modes include so-called even mode, hump mode, and progressive increase mode, and each mode with five and six pulses, respectively. Engine test was conducted with these modes. The experimental results show that diesel HCCI combustion is extremely sensitive to multipulse injection modes and that thermal efficiency can be improved with carefully modulated ones. There are many modes that can reach near zero NOx and smoke emissions, but it is significant to be aware that multipulse injection mode must be carefully designed for higher thermal efficiency.

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