scholarly journals An experiment study of homogeneous charge compression ignition combustion and emission in a gasoline engine

2014 ◽  
Vol 18 (1) ◽  
pp. 295-306
Author(s):  
Jianyong Zhang ◽  
Zhongzhao Li ◽  
Kaiqiang Zhang ◽  
Lei Zhu ◽  
Zhen Huang
Keyword(s):  
Air Temperature ◽  
Gasoline Engine ◽  
Fuel Injection ◽  
Air Pressure ◽  
Compression Ignition ◽  
Effective Pressure ◽  
Indicated Mean Effective Pressure ◽  
Hcci Combustion ◽  
Combustion Duration ◽  
Combustion Phase

Homogenous charge compression ignition (HCCI) technology has exhibited high potential to reduce fuel consumption and NOx emissions over normal spark ignition engines significantly. Optimized kinetic process (OKP) technology is implemented to realize HCCI combustion in a port fuel injection gasoline engine. The combustion and emission characteristics are investigated with variation of intake air temperature, exhaust gas recirculation (EGR) rate and intake air pressure. The results show that intake air temperature has great influence on HCCI combustion characteristic. Increased intake air temperature results in advance combustion phase, shorten combustion duration, and lower indicated mean effective pressure (IMEP). Increased EGR rate retards combustion start phase and prolongs combustion duration, while maximum pressure rising rate and NOx emission are reduced with increase of EGR rate. In the condition with constant fuel flow quantity, increased air pressure leads to retarded combustion phase and lower pressure rising rate, which will reduce the engine knocking tendency. In the condition with constant air fuel ratio condition, fuel injection quantity increases as intake air pressure increases, which lead to high heat release rate and high emission level. The optimal intake air temperature varies in different operating area, which can be tuned from ambient temperature to 220? by heat management system. The combination of EGR and air boost technology could expand operating area of HCCI engine, which improve indicated mean effective pressure from maximum 510kPa to 720kPa.

scholarly journals Effects of intake air temperature on homogenous charge compression ignition combustion and emissions with gasoline and n-heptane

2015 ◽  
Vol 19 (6) ◽  
pp. 1897-1906 ◽  
Author(s):  
Jianyong Zhang ◽  
Zhongzhao Li ◽  
Kaiqiang Zhang ◽  
Xingcai Lv ◽  
Zhen Huang
Keyword(s):  
Air Temperature ◽  
Fuel Injection ◽  
Combustion Stability ◽  
Dual Fuel ◽  
Maximum Pressure ◽  
Heat Management ◽  
Hcci Combustion ◽  
Combustion Duration ◽  
Homogenous Charge Compression Ignition ◽  
Compression Ignition Combustion

In a port fuel injection engine, Optimized kinetic process (OKP) technology is implemented to realize HCCI combustion with dual-fuel injection. The effects of intake air temperature on HCCI combustion and emissions are investigated. The results show that dual-fuel control prolongs HCCI combustion duration and improves combustion stability. Dual-fuel HCCI combustion needs lower intake air temperature than gasoline HCCI combustion, which reduces the requirements on heat management system. As intake air temperature decreases, air charge increases and maximum pressure rising rate decreases. When intake air temperature is about 55?C, HCCI combustion becomes worse and misfire happens. In fixed dual fuel content condition, HC and CO emission decreases as intake air temperature increases. The combination of dual-fuel injection and intake air temperature control can expand operation range of HCCI combustion.

Numerical study on the approach for super-high thermal efficiency in a gasoline homogeneous charge compression ignition lean-burn engine

2019 ◽  
pp. 146808741988924
Author(s):  
Hao Yu ◽  
Wanhua Su
Keyword(s):  
Mechanical Strength ◽  
Thermal Efficiency ◽  
Compression Ignition ◽  
Effective Pressure ◽  
Lean Burn ◽  
Brake Thermal Efficiency ◽  
Indicated Mean Effective Pressure ◽  
Combustion Phase ◽  
Pressure Cycle ◽  
Model Engine

The approach for achieving super-high thermal efficiency in a gasoline homogeneous charge compression ignition lean-burn engine was studied using numerical simulation. A model engine was designed based on the split cycles, including the low-pressure cycle consisted of the turbocharger system and the high-pressure cycle controlled by the variable effective compression ratio ( ε) and the exhaust gas recirculation (EGR). Based on the model engine, load (L) – Φoxy (F) – EGR (E) – ε (E) cooperative control strategy was proposed to optimize the thermal efficiency and its interactive mechanism was clarified. The results revealed that the core of the load (L) – Φoxy (F) – EGR (E) – ε (E) strategy was the simultaneous optimization of the combustion process and the specific heat ratio ( γ) contributing to the piston work maximization. The optimum combustion phase was found in the range of 4°–9° crank angle after top dead center, and highest combustion rate under the rough combustion restriction was also required. Under this precondition, reducing ε to retard the combustion phase appropriately could mitigate the EGR usage to improve the γ. Based on the load (L) – Φoxy (F) – EGR (E) – ε (E) strategy, increasing the load was found to improve the thermal efficiency effectively by reducing the heat transfer loss. The highest brake thermal efficiency of 50% was reached when the gross indicated mean effective pressure was increased to 15 bar under the conventional engine condition. Further increasing the gross indicated mean effective pressure to 35 bar with elevated peak cylinder pressure of 400 bar could improve the brake thermal efficiency to 54% under the enhanced mechanical strength condition. To pursue super-high thermal efficiency, the approach of thermal insulation for the engine was proved to be more effective. It showed the potential to achieve the super-high brake thermal efficiency over 60% and maintain clean combustion by adopting the load (L) – Φoxy (F) – EGR (E) – ε (E) strategy in the model engine with thermal insulation and high mechanical strength.

Improving the Efficiency of Low Temperature Combustion Engines Using a Chamfered Ring-Land

2015 ◽  
Vol 137 (11) ◽  
Author(s):  
Jae Hyung Lim ◽  
Rolf D. Reitz
Keyword(s):  
Combustion Efficiency ◽  
Low Temperature Combustion ◽  
Combustion Engines ◽  
Compression Ignition ◽  
Reactivity Controlled Compression Ignition ◽  
Indicated Mean Effective Pressure ◽  
Hcci Combustion ◽  
Unburned Hydrocarbon ◽  
Piston Crown ◽  
Temperature Combustion

In the present study, a chamfered piston crown design was used in order to reduce unburned hydrocarbon (UHC) emissions from the ring-pack crevice. Compared to the conventional piston design, the chamfered piston showed 17–41% reduction in the crevice-borne UHC emissions in homogeneous charge compression ignition (HCCI) combustion. Through parametric sweeps 6 mm was identified to be a suitable chamfer size and the mechanism of the UHC reduction was revealed. Based on the findings in this study, the chamfered piston design was also tested in dual-fuel reactivity controlled compression ignition (RCCI) combustion. In the tested RCCI case using the chamfered piston the UHC and CO emissions were reduced by 79% and 36%, respectively, achieving 99.5% combustion efficiency. This also improved gross indicated thermal efficiency (gITE) from 51.1% to 51.8% in a 9 bar indicated mean effective pressure (IMEP) RCCI combustion case.

The effects of late intake valve closing and different cam profiles on the in-cylinder flow field and the combustion characteristics of a compression ignition engine

2017 ◽  
Vol 232 (7) ◽  
pp. 853-865 ◽  
Author(s):  
Jaeheun Kim ◽  
Stephen Sungsan Park ◽  
Choongsik Bae
Keyword(s):  
Flow Field ◽  
Nitrogen Oxide ◽  
High Mass ◽  
Compression Ignition ◽  
Effective Pressure ◽  
Intake Valve ◽  
Nitrogen Oxide Emissions ◽  
Trade Off ◽  
Indicated Mean Effective Pressure ◽  
Cam Profile

The effects of the late-intake-valve-closing strategy and the different types of cam profile were observed in a single-cylinder compression ignition research engine. Experiments were carried out with two engine loads in naturally aspirated conditions. The late-intake-valve-closing strategy exhibited an improvement in the conventional trade-off between the nitrogen oxide emissions and the smoke emissions, as stated in other relevant work. However, it was found to be effective only for the premise that a sufficiently high mass of oxygen is trapped inside the cylinder, which ensured that the smoke emissions did not deteriorate with exhaust gas recirculation. This improvement in the trade-off decreased when the global air excess ratio inside the cylinder reached close to unity. The major disadvantages of the late-intake-valve-closing strategy included deterioration in the indicated mean effective pressure and the reduced mass of oxygen trapped inside the cylinder. The decrease in the indicated mean effective pressure was attributed to the reduction in the effective compression ratio followed by the reduction in the thermal efficiency in terms of the thermodynamics. The volumetric efficiency decreased owing to the backflow of the in-cylinder charge into the intake manifold. This implied that intake boosting was necessary not only to recover the efficiency to the original level but also to extend the engine load with a sufficient amount of air. The manipulation of cam profiles yielded further improvement in the trade-off relationship between the nitrogen oxide emissions and the smoke emissions. The flow field measurements obtained using particle image velocimetry and direct imaging of the combustion of the fuel spray demonstrated that the asymmetric cam profile effectively increased the swirl ratio inside the cylinder. Further improvement in the trade-off relationship between the nitrogen oxide emissions and the smoke emissions was realized because of this increased swirl intensity, which provided a better environment for air utilization. The smoke emissions were suppressed without a significant increase in the nitrogen oxide emissions.

Effects of Fuel Octane Number on Homogeneous Charge Compression Ignition (HCCI) Combustion with Rapid Compression Machine

2012 ◽  
Vol 455-456 ◽  
pp. 339-343
Author(s):  
You Kun Wang ◽  
Peng Cheng ◽  
Yun Kai Wang ◽  
Hua Li ◽  
Ying Nan Guo
Keyword(s):  
Octane Number ◽  
Homogeneous Charge Compression Ignition ◽  
Maximum Pressure ◽  
Compression Ignition ◽  
Rapid Compression Machine ◽  
Hcci Combustion ◽  
Combustion Duration ◽  
Rapid Compression ◽  
Start Of Combustion ◽  
Homogeneous Charge

The effects of fuel octane number (RON) on homogeneous charge compression ignition (HCCI) combustion were studied under different combustion boundary conditions on a rapid compression machine. The results show that the maximum pressure raise rate and maximum combustion temperature decreased as the RON increased while the start of combustion is delayed and the combustion duration is shortened at the same time.

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.

Experimental optimization of a direct injection homogeneous charge compression ignition gasoline engine using split injections with fully automated microgenetic algorithms

2003 ◽  
Vol 4 (1) ◽  
pp. 47-60 ◽  
Author(s):  
M Canakci ◽  
R D Reitz
Keyword(s):  
Homogeneous Charge Compression Ignition ◽  
Gasoline Engine ◽  
Fuel Injection ◽  
Direct Injection ◽  
Operating Conditions ◽  
Spray Angle ◽  
Injection Timing ◽  
Compression Ignition ◽  
Engine Operation ◽  
Homogeneous Charge

Homogeneous charge compression ignition (HCCI) is receiving attention as a new low-emission engine concept. Little is known about the optimal operating conditions for this engine operation mode. Combustion under homogeneous, low equivalence ratio conditions results in modest temperature combustion products, containing very low concentrations of NOx and particulate matter (PM) as well as providing high thermal efficiency. However, this combustion mode can produce higher HC and CO emissions than those of conventional engines. An electronically controlled Caterpillar single-cylinder oil test engine (SCOTE), originally designed for heavy-duty diesel applications, was converted to an HCCI direct injection (DI) gasoline engine. The engine features an electronically controlled low-pressure direct injection gasoline (DI-G) injector with a 60° spray angle that is capable of multiple injections. The use of double injection was explored for emission control and the engine was optimized using fully automated experiments and a microgenetic algorithm optimization code. The variables changed during the optimization include the intake air temperature, start of injection timing and the split injection parameters (per cent mass of fuel in each injection, dwell between the pulses). The engine performance and emissions were determined at 700 r/min with a constant fuel flowrate at 10 MPa fuel injection pressure. The results show that significant emissions reductions are possible with the use of optimal injection strategies.

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