Optimization of piston bowl and valve system in compression ignition engine fueled with gasoline/diesel/polyoxymethylene dimethyl ethers for high efficiency

2019 ◽  
pp. 146808741986538
Author(s):  
Bowen Li ◽  
Haoye Liu ◽  
Linjun Yu ◽  
Zhi Wang ◽  
Jianxin Wang
Keyword(s):  
Heat Transfer ◽  
Thermal Efficiency ◽  
High Efficiency ◽  
Compression Ignition ◽  
Combustion Mode ◽  
Compression Ignition Engine ◽  
Valve System ◽  
Percentage Points ◽  
Polyoxymethylene Dimethyl Ethers ◽  
Variable Valve

Polyoxymethylene dimethyl ethers, with excellent volatility and oxygen content of up to 49%, have great potential to improve engine performance and emission characteristics. In this study, experiments were carried out in a single-cylinder engine fueled with gasoline/diesel/polyoxymethylene dimethyl ethers blend fuel using multiple premixed compression ignition combustion mode along with engine optimization to exploit the high-efficiency potential. The thermal efficiency was increased by 9.4 percentage points after transforming the combustion mode from conventional diesel mode to gasoline/diesel/polyoxymethylene dimethyl ethers multiple premixed compression ignition mode. A fully variable valve system and a redesigned low-heat-transfer piston were used to further improve the thermal efficiency. The low-heat-transfer piston had a 15% lower area–volume ratio compared with the original ω-type piston. By replacing the original ω-type piston with the low-heat-transfer piston, the heat transfer loss was reduced by 2.29 percentage points and thus indicated thermal efficiency could be increased by 2.37 percentage points, which was up to 50.03%. On the basis of the low-heat-transfer piston, indicated thermal efficiency could be further increased to 51.09% with the application of fully variable valve system due to the longer ignition delay and more premixed combustion. At the same time, NOX emissions could be controlled below 0.4 g/kW·h using high exhaust gas recirculation ratio, which equaled the NOX emission limit of Euro VI standard. Although soot emissions could be increased due to weak turbulence and insufficient intake charge using the low-heat-transfer piston and fully variable valve system, it was still lower than those of the original diesel engines.

scholarly journals A numerical investigation of isobaric combustion strategy in a compression ignition engine

2020 ◽  
pp. 146808742097037
Author(s):  
Xinlei Liu ◽  
Hammam Aljabri ◽  
Balaji Mohan ◽  
Rafig Babayev ◽  
Jihad Badra ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Thermal Efficiency ◽  
High Efficiency ◽  
Fluid Dynamic ◽  
Spray Angle ◽  
Compression Ignition ◽  
Swirl Ratio ◽  
Combustion Mode ◽  
Compression Ignition Engine ◽  
Dynamic Simulations

Three-dimensional computational fluid dynamic simulations were conducted to study the means to achieve isobaric combustion mode in a compression ignition engine, which is intended to be used in the high-efficiency double compression-expansion engine (DCEE) concept. Compared to the conventional diesel combustion mode, the isobaric combustion mode generated a significantly lower peak combustion pressure, which was beneficial for the high load extension. For both combustion modes, the ignition was triggered downstream of the nozzle, with the heat release dominated by HCO + O2 = CO+HO2, while the injection-combustion duration for the isobaric combustion mode was significantly longer. The effects of swirl ratio, spray angle, and piston geometries on the isobaric combustion at various engine loads were also investigated. The higher swirl ratio resulted in a higher heat transfer loss and thus lower thermal efficiency. Due to the higher air utilization rates and lower heat transfer losses, cases with spray angles of 140° and 150° generated the higher thermal efficiencies. The piston bowl geometry was found to have a significant impact on the mixing and combustion processes, especially at high engine load conditions. For the conditions under study, the original piston geometry with a swirl ratio of 0 and a spray angle of 140° demonstrated the highest thermal efficiency for the isobaric combustion mode. The results of this work will provide guidance in the practical design and implementation of the DCEE concept.

scholarly journals Improving the Thermal Efficiency of the Homogeneous Charge Compression Ignition Engine by Using Various Combustion Patterns

Energies ◽  
2018 ◽  
Vol 11 (11) ◽  
pp. 3002 ◽  
Author(s):  
Yuh-Yih Wu ◽  
James H. Wang ◽  
Faizan Mushtaq Mir
Keyword(s):  
Thermal Efficiency ◽  
High Efficiency ◽  
Homogeneous Charge Compression Ignition ◽  
Combustion Engine ◽  
Combustion Characteristics ◽  
Compression Ignition ◽  
Compression Ignition Engine ◽  
Cycle Simulation ◽  
Homogeneous Charge ◽  
Wiebe Function

The efficiency of an internal combustion engine (ICE) is essential for automobiles and motorcycles. Several studies have demonstrated that the homogeneous charge compression ignition (HCCI) is a promising technology for realizing engines with high efficiency and low emissions. This study investigated the combustion characteristics of the HCCI using a 125 cc motorcycle engine with n-heptane fuel. The engine performance, combustion characteristics, and thermal efficiency were analyzed from experimental data. The results revealed that a leaner air–fuel mixture led to higher engine efficiency and output. The improvement of engine output is contradictory to the general trend. Energy balance analysis revealed that lower heat loss, due to the low cylinder gas temperature of lean combustion, contributed to higher efficiency. A double-Wiebe function provided excellent simulation of the mass fraction burned (MFB) of the HCCI. Air cycle simulation with the MFB, provided by the double-Wiebe function, was executed to investigate this phenomenon. The results indicated that a better combustion pattern led to higher thermal efficiency, and thus the engine output and thermal efficiency do not require a fast combustion rate in an HCCI engine. A better combustion pattern can be achieved by adjusting air–fuel ratio (AFR) and the rates of dual fuel and exhaust gas recirculation (EGR).

Engine performance and emission characteristics of a compression ignition engine fuelled with diesel/dimethoxymethane blends

2005 ◽  
Vol 219 (7) ◽  
pp. 905-914 ◽  
Author(s):  
Y Ren ◽  
Z H Huang ◽  
D M Jiang ◽  
L X Liu ◽  
K Zeng ◽  
...  
Keyword(s):  
Thermal Efficiency ◽  
Mass Fraction ◽  
Volume Fraction ◽  
Engine Performance ◽  
Compression Ignition ◽  
Compression Ignition Engine ◽  
Performance And Emission ◽  
Fuel Blends ◽  
Performance And Emissions ◽  
Combustion Phase

The performance and emissions of a compression ignition engine fuelled with diesel/dimethoxymethane (DMM) blends were studied. The results showed that the engine's thermal efficiency increased and the diesel equivalent brake specific fuel consumption (b.s.f.c.) decreased as the oxygen mass fraction (or DMM mass fraction) of the diesel/DMM blends increased. This change in the diesel/DMM blends was caused by an increased fraction of the premixed combustion phase, an oxygen enrichment, and an improvement in the diffusive combustion phase. A remarkable reduction in the exhaust CO and smoke can be achieved when operating on the diesel/DMM blend. Flat NO x/smoke and thermal efficiency/smoke curves are presented when operating on the diesel/DMM fuel blends, and a simultaneous reduction in both NO x and smoke can be realized at large DMM addition. Thermal efficiency and NO x give the highest value at 2 per cent oxygen mass fraction (or 5 per cent DMM volume fraction) for the combustion of diesel/DMM blends.

Numerical study on combustion characteristics of six-stroke-cycle gasoline compression ignition engine with continuously variable valve duration valve technology

2019 ◽  
Vol 22 (1) ◽  
pp. 165-183 ◽  
Author(s):  
Oudumbar Rajput ◽  
Youngchul Ra ◽  
Kyoung-Pyo Ha ◽  
You-Sang Son
Keyword(s):  
Numerical Study ◽  
Power Stroke ◽  
Compression Ignition ◽  
Ignition Timing ◽  
Compression Ignition Engine ◽  
Engine Operation ◽  
Wide Range ◽  
Negative Valve Overlap ◽  
Variable Valve ◽  
Valve Overlap

Engine performance and emissions of a six-stroke gasoline compression ignition engine with a wide range of continuously variable valve duration control were numerically investigated at low engine load conditions. For the simulations, an in-house three-dimensional computational fluid dynamics code with high-fidelity physical sub-models was used, and the combustion and emission kinetics were computed using a reduced kinetics mechanism for a 14-component gasoline surrogate fuel. Variation of valve timing and duration was considered under both positive valve overlap and negative valve overlap including the rebreathing of intake valves via continuously variable valve duration control. Close attention was paid to understand the effects of two additional strokes of the engine cycle on the thermal and chemical conditions of charge mixtures that alter ignition, combustion and energy recovery processes. Double injections were found to be necessary to effectively utilize the additional two strokes for the combustion of overly mixed lean charge mixtures during the second power stroke. It was found that combustion phasing in both power strokes is effectively controlled by the intake valve closure timing. Engine operation under negative valve overlap condition tends to advance the ignition timing of the first power stroke but has minimal effect on the ignition timing of second power stroke. Re-breathing was found to be an effective way to control the ignition timing in second power stroke at a slight expense of the combustion efficiency. The operation of a six-stroke gasoline compression ignition engine could be successfully simulated. In addition, the operability range of the six-stroke gasoline compression ignition engine could be substantially extended by employing the continuously variable valve duration technique.

scholarly journals Experimental Research on Controllability and Emissions of Jet-Controlled Compression Ignition Engine

Energies ◽  
2019 ◽  
Vol 12 (15) ◽  
pp. 2936 ◽  
Author(s):  
Hua Tian ◽  
Jingchen Cui ◽  
Tianhao Yang ◽  
Yao Fu ◽  
Jiangping Tian ◽  
...  
Keyword(s):  
Thermal Efficiency ◽  
High Speed ◽  
Compression Ignition ◽  
Compression Ignition Engine ◽  
Engine Emissions ◽  
Spark Timing ◽  
Crank Angle ◽  
Marine Engines ◽  
Si Engines ◽  
Ci Engines

Low-temperature combustions (LTCs), such as homogeneous charge compression ignition (HCCI), could achieve high thermal efficiency and low engine emissions by combining the advantages of spark-ignited (SI) engines and compression-ignited (CI) engines. Robust control of the ignition timing, however, still remains a hurdle to practical use. A novel technology of jet-controlled compression ignition (JCCI) was proposed to solve the issue. JCCI combustion phasing was controlled by hot jet formed from pre-chamber spark-ignited combustion. Experiments were done on a modified high-speed marine engine for JCCI characteristics research. The JCCI principle was verified by operating the engine individually in the mode of JCCI and in the mode of no pre-chamber jet under low- and medium-load working conditions. Effects of pre-chamber spark timing and intake charge temperature on JCCI process were tested. It was proven that the combustion phasing of the JCCI engine was closely related to the pre-chamber spark timing. A 20 °C temperature change of intake charge only caused a 2° crank angle change of the start of combustion. Extremely low nitrogen oxides (NOx) emission was achieved by JCCI combustion while keeping high thermal efficiency. The JCCI could be a promising technology for dual-fuel marine engines.

Preparation of Jatropha Biodiesel Using Hydrotalcite Catalyst and its Performance on Diesel Engine

2011 ◽  
Vol 110-116 ◽  
pp. 1368-1373 ◽  
Author(s):  
Amar P. Pandhare ◽  
S. G. Wagholikar ◽  
R. B. Jadhav Sachin Musale ◽  
A. S. Padalkar
Keyword(s):  
Diesel Engine ◽  
Thermal Efficiency ◽  
Specific Energy Consumption ◽  
Exhaust Emissions ◽  
Effect Of Temperature ◽  
Compression Ignition ◽  
Performance Parameters ◽  
Jatropha Oil ◽  
Compression Ignition Engine ◽  
Ci Engines

The heterogeneous catalyst are environment friendly and render the process simplified. A wide variety of solid bases have been examined for this process. The present work reports the use of hydrotalcite catalyst for the synthesis of Biodiesel from jatropha oil. An experimental investigation has been carried out to analyze the performance and emission characteristics of a compression ignition engine fuelled with Jatropha oil and its blends (10%, 20%, 40%, 50%, and 60 % ) with mineral diesel. The effect of temperature on the viscosity of Jatropha oil has also been investigated. A series of engine tests, have been conducted using each of the above fuel blends for comparative performance evaluation. The performance parameters evaluated include thermal efficiency, brake specific fuel consumption (BSFC), brake specific energy consumption (BSEC), and exhaust gas temperature whereas exhaust emissions include mass emissions of CO, HC, NO. These parameters were evaluated in a single cylinder compression ignition diesel engine. The results of the experiment in each case were compared with baseline data of mineral diesel. Significant improvements have been observed in the performance parameters of the engine as well as exhaust emissions. The gaseous emissions of oxide of nitrogen from all blends are lower than mineral diesel at all engine loads. Jatropha oil blends with diesel (up to 50% v/v) can replace diesel for operating the CI engines giving lower emissions and improved engine performance. More over results indicated that B20 have closer performance to diesel and B100 have lower brake thermal efficiency mainly due to its high viscosity compared to diesel.

Low Cetane Fuels in Compression Ignition Engine to Achieve LTC

2011 ◽  
Author(s):  
Swami Nathan Subramanian ◽  
Stephen Ciatti
Keyword(s):  
Low Temperature ◽  
Internal Combustion Engines ◽  
High Efficiency ◽  
Fuel Efficiency ◽  
Nox Emissions ◽  
Low Temperature Combustion ◽  
Compression Ignition ◽  
Oxides Of Nitrogen ◽  
Compression Ignition Engine ◽  
Conventional Combustion

The conventional combustion processes of Spark Ignition (SI) and Compression Ignition (CI) have their respective merits and demerits. Internal combustion engines use certain fuels to utilize those conventional combustion technologies. High octane fuels are required to operate the engine in SI mode, while high cetane fuels are preferable for CI mode of operation. Those conventional combustion techniques struggle to meet the current emissions norms while retaining high efficiency. In particular, oxides of nitrogen (NOx) and particulate matter (PM) emissions have limited the utilization of diesel fuel in compression ignition engines, and conventional gasoline operated SI engines are not fuel efficient. Advanced combustion concepts have shown the potential to combine fuel efficiency and improved emissions performance. Low Temperature Combustion (LTC) offers reduced NOx and PM emissions with comparable modern diesel engine efficiencies. The ability of premixed, low-temperature compression ignition to deliver low PM and NOx emissions is dependent on achieving optimal combustion phasing. Variations in injection pressures, injection schemes and Exhaust Gas Recirculation (EGR) are studied with low octane gasoline LTC. Reductions in emissions are a function of combustion phasing and local equivalence ratio. Engine speed, load, EGR quantity, compression ratio and fuel octane number are all factors that influence combustion phasing. Low cetane fuels have shown comparable diesel efficiencies with low NOx emissions at reasonably high power densities.

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