Experimental investigation of diesel/gasoline dual-fuel premixed compression ignition strategies for high thermal efficiency and high load extension

2017 ◽  
Vol 232 (10) ◽  
pp. 1374-1384 ◽  
Author(s):  
Jeongwoo Lee ◽  
Sanghyun Chu ◽  
Kyoungdoug Min ◽  
Hyunsung Jung ◽  
Hyounghyoun Kim ◽  
...  
Keyword(s):  
Thermal Efficiency ◽  
Ignition Delay ◽  
Load Condition ◽  
High Load ◽  
Premixed Combustion ◽  
Dual Fuel ◽  
Compression Ignition ◽  
Lean Premixed Combustion ◽  
Diesel Injection ◽  
Low Load

In this study, two different operating strategies of gasoline and diesel dual-fuel premixed compression ignition (PCI) were investigated by using a single cylinder compression ignition engine. Verification of high thermal efficiency potential under the low load condition and the suppression of the maximum in-cylinder pressure rise rate (PRRmax) under the relatively high load condition were considered in this study. Two approaches to implement dual-fuel PCI were considered. The first approach (A-mode PCI) was an early diesel injection with very leaner overall equivalence ratio condition. In this case, a high exhaust gas recirculation (EGR) rate was not needed because lean premixed combustion promised to provide low nitrogen oxides (NOx) and particulate matter (PM) emissions. The second method (B-mode PCI) involved the use of a high EGR rate to moderate dual-fuel combustion with adjusting diesel injection timing. The first operating strategy prolonged the ignition delay via early diesel injection and lean mixture condition; in this manner, a high EGR helped to increase ignition delay. The experimental result showed that the A-mode PCI strategy promised higher gross indicated thermal efficiency (GIE) than that of the B-mode PCI. However, the B-mode PCI strategy provided a lower PRRmax than that of the first case. By applying the A-mode PCI, which was implemented by the early diesel injection with overall lean premixed combustion, a high GIE of 47.8 % could be obtained under low speed and low load condition. In addition, the dual-fuel PCI operating range could be increased using a gross indicated mean effective pressure (gIMEP) of 14 bar at 2000 r/min with a low PRRmax of 7 bar/deg (constraint 10 bar/deg) by applying the B-mode PCI strategy, which split the heat release rate (HRR) peaks to enable smooth combustion.

scholarly journals Effects of internal/external EGR and combustion phase on gasoline compression ignition at low-load condition

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Jingyu Gong ◽  
Binbin Yang ◽  
Leilei Liu ◽  
Yue Liang ◽  
Zhifa Zhang ◽  
...  
Keyword(s):  
Thermal Efficiency ◽  
Load Condition ◽  
Soot Emission ◽  
Compression Ignition ◽  
Total Heat Loss ◽  
Engine Model ◽  
Low Load ◽  
Combustion Phase ◽  
Test Engine ◽  
Hc Emissions

Abstract A single-cylinder test engine model was built by GT-Power software, and the effects of internal exhaust gas recirculation (i-EGR), external EGR (e-EGR), i-EGR/e-EGR coupling and the crank angle degree at which 50% of total heat loss has taken place (CA50) on combustion and emission characteristics of gasoline compression ignition at low-load condition were analysed. The results show that the ignition delay period with e-EGR was extended slightly with the increased EGR ratio, while that with i-EGR strategy first shortened and then extended, and that the optimised indicated thermal efficiency could be achieved using a small amount of i-EGR. With the same EGR ratio, nitrogen oxide (NO X ) emission is more likely to be suppressed by i-EGR, while soot emission was more deteriorated, and the superior trade-off relationship between carbon monoxide (CO)/hydrocarbon (HC) emissions and NO X emission was attained by the combination of lower i-EGR ratios and CA50 closed to top dead centre. When using i-EGR/e-EGR coupling with total EGR ratio being fixed, the indicated thermal efficiency was decreased by increasing i-EGR ratio, while the lower NO X , CO and HC emissions could be realised, but only with the consequence that soot emission increased.

A Study of Injection Strategy to Achieve High Load Points for Gasoline Compression Ignition (GCI) Operation

2017 ◽  
Author(s):  
Khanh Cung ◽  
Stephen Ciatti
Keyword(s):  
High Efficiency ◽  
Cetane Number ◽  
Load Condition ◽  
Low Noise ◽  
High Load ◽  
Premixed Combustion ◽  
Injection Timing ◽  
Compression Ignition ◽  
Injection Strategy ◽  
Engine Load

Many studies have shown that gasoline compression ignition (GCI) can replace conventional diesel combustion (CDC) by achieving high efficiency and low smoke and toxic gaseous emissions simultaneously. This is due to the low cetane number of gasoline that results in long ignition delay, allowing very advanced injection timing. This gives even longer time for fuel-air mixing, thus resulting in locally lean combustion that produces low particulate matter (PM). However, GCI operation faces challenges at high engine load condition. At high load conditions, large amounts of fuel injected early for premixed combustion can lead to high combustion noise from premixed combustion. Meanwhile, more fuel late injected late leads to poor mixing, hence higher smoke. Multiple injections can offer the flexibility in controlling the in-cylinder fuel stratification level. In this study, moderate to high engine loads of 8 to 14 bar BMEP were accomplished by utilizing an optimal multiple injection scheme. Injection timing of pilot, main, and post injections was investigated individually for its effect on the emission and engine performance. A moderate level of exhaust gas recirculating (EGR) was used to achieve low temperature combustion (LTC) condition. While higher EGR reduced NOx significantly due to lower combustion temperature, it affected the maximum boost that could be acquired by the turbocharger due to the reduction in exhaust enthalpy. During the engine load/speed sweep, calculations of combustion, thermodynamics, gas exchange, and mechanical efficiencies were analyzed to identify factor that needs to be improved for GCI operation. This study also demonstrates the importance of injection strategy including high injection pressure to attain high load points with low smoke and low noise.

An Investigation of the Combustion Process of a Heavy-Duty Natural Gas-Diesel Dual Fuel Engine

2018 ◽  
Vol 140 (9) ◽  
Author(s):  
Hailin Li ◽  
Shiyu Liu ◽  
Chetmun Liew ◽  
Timothy Gatts ◽  
Scott Wayne ◽  
...  
Keyword(s):  
Thermal Efficiency ◽  
Combustion Process ◽  
Combustion Efficiency ◽  
High Load ◽  
Dual Fuel ◽  
Diffusion Combustion ◽  
Cylinder Pressure ◽  
Brake Thermal Efficiency ◽  
Combustion Duration ◽  
Low Load

This paper investigates the effect of the addition of natural gas (NG) and engine load on the cylinder pressure, combustion process, brake thermal efficiency, and methane combustion efficiency of a heavy-duty NG-diesel dual fuel engine. Significantly increased peak cylinder pressure (PCP) was only observed with the addition of NG at 100% load. The addition of a relatively large amount NG at high load slightly retarded the premixed combustion, significantly increased the peak heat release rate (PHRR) of the diffusion combustion, decreased the combustion duration, and advanced combustion phasing. The accelerated combustion process and increased heat release rate (HRR) at high load were supported by the increased NOx emissions with the addition of over 3% NG (vol.). By comparison, when operated at low load, the addition of a large amount of NG decreased the PHRR of the premixed combustion and slightly increased the PHRR during the late diffusion combustion. Improved brake thermal efficiency was only observed with the addition of a relatively large amount of NG at high load. The improved thermal efficiency was due to a decrease in combustion duration and the shifting of the combustion phasing toward the optimal phasing. The overall combustion efficiency of the dual fuel operation was always lower than diesel-only operation as indicated by the excess emissions of the unburned methane and carbon monoxide from dual fuel engine. This deteriorated the potential of dual fuel engine in further improving the brake thermal efficiency although the combustion duration of dual fuel engine at high load was much shorter than diesel only operation. The addition of NG at low load should be avoided due to the low combustion efficiency of NG and the decreased thermal efficiency. Approaches capable of further improving the in-cylinder combustion efficiency of NG should enable further improvement in the brake thermal efficiency.

Parametric Study to Optimize Gasoline Compression Ignition Operation under Low Load Condition Using CFD

2021 ◽  
Author(s):  
Jihad Badra ◽  
Alma Alhussaini ◽  
Jaeheon Sim ◽  
Yoann Viollet ◽  
Amer Amer
Keyword(s):  
Parametric Study ◽  
Load Condition ◽  
Compression Ignition ◽  
Low Load

Combustion characteristics of compressed natural gas/diesel dual-fuel turbocharged compressed ignition engine

2003 ◽  
Vol 217 (9) ◽  
pp. 833-838 ◽  
Author(s):  
Liu Shenghua ◽  
Zhou Longbao ◽  
Wang Ziyan ◽  
Ren Jiang
Keyword(s):  
Natural Gas ◽  
Ignition Delay ◽  
Combustion Characteristics ◽  
Operating Conditions ◽  
Dual Fuel ◽  
Compressed Natural Gas ◽  
Delay Effects ◽  
Low Load ◽  
Performance And Emissions ◽  
Ci Engine

The combustion characteristics of a turbocharged natural gas and diesel dual-fuelled compression ignition (CI) engine are investigated. With the measured cylinder pressures of the engine operated on pure diesel and dual fuel, the ignition delay, effects of pilot diesel and engine load on combustion characteristics are analysed. Emissions of HC, CO, NOx and smoke are measured and studied too. The results show that the quantity of pilot diesel has important effects on the performance and emissions of a dual-fuel engine at low-load operating conditions. Ignition delay varies with the concentration of natural gas. Smoke is much lower for the developed dual-fuel engine under all the operating conditions.

Assessment of a Syngas-Diesel Dual Fuelled Compression Ignition Engine

2010 ◽  
Author(s):  
Bibhuti B. Sahoo ◽  
Niranjan Sahoo ◽  
Ujjwal K. Saha
Keyword(s):  
Diesel Engine ◽  
Thermal Efficiency ◽  
Gas Flow ◽  
Direct Injection ◽  
Dual Fuel ◽  
Exhaust Gas ◽  
Compression Ignition ◽  
Gas Temperature ◽  
Compression Ignition Engine ◽  
Exhaust Gas Temperature

Synthesis gas (Syngas), a mixture of hydrogen and carbon monoxide, can be manufactured from natural gas, coal, petroleum, biomass, and even from organic wastes. It can substitute fossil diesel as an alternative gaseous fuel in compression ignition engines under dual fuel operation route. Experiments were conducted in a single cylinder, constant speed and direct injection diesel engine fuelled with syngas-diesel in dual fuel mode. The engine is designed to develop a power output of 5.2 kW at its rated speed of 1500 rpm under variable loads with inducted syngas fuel having H2 to CO ratio of 1:1 by volume. Diesel fuel as a pilot was injected into the engine in the conventional manner. The diesel engine was run at varying loads of 20, 40, 60, 80 and 100%. The performance of dual fuel engine is assessed by parameters such as thermal efficiency, exhaust gas temperature, diesel replacement rate, gas flow rate, peak cylinder pressure, exhaust O2 and emissions like NOx, CO and HC. Dual fuel operation showed a decrease in brake thermal efficiency from 16.1% to a maximum of 20.92% at 80% load. The maximum diesel substitution by syngas was found 58.77% at minimum exhaust O2 availability condition of 80% engine load. The NOx level was reduced from 144 ppm to 103 ppm for syngas-diesel mode at the best efficiency point. Due to poor combustion efficiency of dual fuel operation, there were increases in CO and HC emissions throughout the range of engine test loads. The decrease in peak pressure causes the exhaust gas temperature to rise at all loads of dual fuel operation. The present investigation provides some useful indications of using syngas fuel in a diesel engine under dual fuel operation.

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