Numerical Simulations of Natural Gas Injection Pressure Effects on a Direct Injected, Pilot Ignited, Natural Gas Engine

Pilot-ignited direct injection of natural gas fueling of a compression ignition engine has been shown to keep high thermal efficiency as diesel engines. To further investigate the combustion process, the effect of natural gas injection pressure on combustion in a diesel engine fueled with pilot-ignited directly-injected natural gas was studied by multidimensional simulations while engine speed and other injection parameters were held constant. NO emissions are increased by higher gas injection pressure without significantly affecting cylinder pressure. By increasing gas injection pressure, HC emissions are reduced with the increase of cylinder temperature. The data got contributes to the development of the pilot-ignited high pressure direct injection natural gas engine.

Download Full-text

Investigation on the combustion noise of a pilot-ignited direct-injection natural-gas engine

Proceedings of the Institution of Mechanical Engineers Part D Journal of Automobile Engineering ◽

10.1177/0954407016629268 ◽

2016 ◽

Vol 230 (14) ◽

pp. 1942-1957 ◽

Cited By ~ 2

Author(s):

Menghan Li ◽

Qiang Zhang ◽

Guoxiang Li

Keyword(s):

Natural Gas ◽

Direct Injection ◽

Injection Pressure ◽

Pressure Level ◽

Combustion Noise ◽

Injection Timing ◽

Cylinder Pressure ◽

Engine Load ◽

Gas Engine ◽

Natural Gas Engine

In this paper, the effects of the injection timing, the injection pressure and the engine load on the combustion noise of a pilot-ignited direct-injection natural-gas engine were explored by analysing the separate components of the in-cylinder pressure. The results suggested that retarding the injection timing and reducing the injection pressure are effective ways of controlling the combustion noise. This can be attributed to the promoted burning rate at advanced injection timings and to the increased injection pressure. However, the effect of the engine load seems to be less obvious, although the resonance pressure level appears to increase with increasing engine load; the estimated combustion noise shows a decreasing tendency.

Download Full-text

Micro-pilot-induced Ignition Diesel/ Natural Gas Engine Control System Development and Engine Performance /Emission Optimization

10.24868/issn.2631-8741.2018.010 ◽

2018 ◽

Author(s):

G Zhao

Keyword(s):

Control System ◽

Natural Gas ◽

Gas Injection ◽

Injection Pressure ◽

Dual Fuel ◽

Injection Timing ◽

Gas Engine ◽

Natural Gas Engine ◽

Driving Circuit ◽

Injection Ratio

Diesel/natural gas dual fuel engine is acquiring more and more attention due to its potential to reduce NOX and soot emission simultaneously. Micro-pilot-induced diesel ignition natural gas engine is a popular manner to further improve the emission reduction capability of dual fuel engine. A six cylinder, four stroke, commonrail diesel engine is converted into dual fuel engine. Natural gas is injected into the intake manifold after the throttle. Five gas injection valves are used to control natural gas flow rate. Based to the established fuel supply system, a dual fuel control system is developed by using MS9S12XEP100 MCU. Voltage boosting circuit, fuel injector driving circuit, gas injection valve driving circuit and MeUn driving circuit are integrated on the platform of MCU hardware. Two ECU is connected to each other by CAN bus and several I/O ports to fulfil the fuel injection functional requirement. A software framework involves gas injection timing synchronization, fuel mode managing, multi-time injection. A MAP based fresh air mass flow rate and intake charge efficiency model is integrated in the MCU to calculate the fresh air quality in cylinder. The last part is performance optimization research at low load. Ignition diesel is divided into two stages, and the first injection timing, first injection ratio and injection pressure are used as controllable parameter to reduce NOX and HC emission. Experimental result reveal that by dividing ignition injection into two stage and advancing first injection to 60°CA BTDC CH4 emission can be reduced by 77% while NOX remains unchanged. Increasing the first injection ratio and injection pressure can also reduce THC emission. If injection pressure is higher than 75MPa, the effect of HC reduction effect is not that obvious. Experimental results shows that developed control system can accomplish the functional requirements of dual fuel engine management. Emission test results demonstrate that IMO TierII can be satisfied at diesel mode. DF mode emission performance can meet the requirement of IMO TierIII. Furthermore, as the first domestic product dual fuel dedicated control system, which has passed through the CCS authentication in China, the engine emission level can meet the current and upcoming China’s emission standard on non-road engine on the premise of guaranteeing engine power and economy.

Download Full-text

Impacts of Ignition and Jet Timing on Natural Gas Engine Start Process

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.1070-1072.1748 ◽

2014 ◽

Vol 1070-1072 ◽

pp. 1748-1751

Author(s):

Bo Wen Zou ◽

Jing Bo Li ◽

Jun Gang Liu

Keyword(s):

Natural Gas ◽

Engine Speed ◽

Direct Injection ◽

Ignition Timing ◽

Gas Engine ◽

Idle Speed ◽

Natural Gas Engine ◽

Hc Emissions ◽

Start Process ◽

Engine Start

Based on modified natural gas direct injection engine, we studied the impacts of ignition timing and jet timing on natural gas engine start process in this paper. The results shows that: when the first jet ignition occurs in the first compression stroke, the engine reaches idle speed 400rpm fastest; as the jet timing is delayed, emissions during engine start is gradually reduced, but when the jet late, HC surge occurs, the emissions deteriorates; with the ignition advance angle increasing, the engine speed growth accelerates, the peak moves forward; with the ignition advance angle increasing, HC emissions peak increases, the peak moves forward.

Download Full-text

Pyrometric imaging of soot processes in a pilot ignited direct injected natural gas engine

International Journal of Engine Research ◽

10.1177/1468087420919196 ◽

2020 ◽

pp. 146808742091919

Author(s):

Mahdiar Khosravi ◽

Gordon McTaggart-Cowan ◽

Patrick Kirchen

Keyword(s):

Natural Gas ◽

Heat Release ◽

Release Rate ◽

Soot Formation ◽

Gas Injection ◽

Injection Pressure ◽

Gas Engine ◽

Natural Gas Engine ◽

Oxidation Processes ◽

Piston Bowl

This work assesses the soot formation and oxidation processes in a high-pressure direct injection natural gas engine using simultaneous high-speed two-colour pyrometry and OH* chemiluminescence imaging. A parametric investigation considers the effects of fuel injection pressure, injection duration and relative pilot and natural gas injection timings. A typical combustion event consists of natural gas being ignited by diesel pilot combustion products, followed by partially premixed combustion of natural gas near the piston bowl wall. Soot is formed as natural gas is injected into this reaction zone. A toroidal soot cloud forms and grows towards the centre of the piston bowl. For the range of operating conditions tested, the peak apparent heat release rate and the onset of detectable soot were correlated, as were the timing of the peak soot fraction and end of natural gas injection. The latter indicates that the soot formation and transition to a net oxidation process are strongly influenced by the injection process, similar to diesel engines. Changes in the relative timing of the diesel pilot and natural gas injections influenced natural gas premixing times, with increased premixing leading to a higher peak apparent heat release rate and lower peak soot fraction. The injection pressure affected the peak soot fraction though enhanced oxidation was expected to ultimately reduce the engine-out soot for higher injection pressures. Based on this parametric investigation, an existing conceptual model of pilot ignited direct injected natural gas combustion is extended to also describe the soot formation and oxidation processes.

Download Full-text

Numerical Study of Effect of Injection Parameters on Combustion and Emission Performance of a Direct Injection Diesel-Natural Gas Engine

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.945-949.2806 ◽

2014 ◽

Vol 945-949 ◽

pp. 2806-2809

Author(s):

Gen Miao Guo ◽

Zhi Xia He ◽

Xiu Xiu Sun ◽

Zhou Rong Zhang ◽

Xi Cheng Tao

Keyword(s):

Natural Gas ◽

Numerical Study ◽

Direct Injection ◽

Gas Injection ◽

Three Dimensional ◽

Injection Velocity ◽

Gas Engine ◽

Emission Performance ◽

Natural Gas Engine ◽

Start Of Injection

By using AVL FIRE code, three-dimensional numerical simulations of the diesel-natural gas injection characteristics in a direct injection diesel-natural gas engine were conducted. The effects of the start of injection (SOI) of the pilot diesel and natural gas injection velocity on combustion and emission performance were investigated. The results showed that diesel-natural gas injection characteristics have an important influence on the subsequent combustion and emission. NO and Soot emission performance is better when the SOI was 36°BTDC (Before Top Dead Center), and a larger natural gas injection velocity usually leads to a lower engine economical efficiency.

Download Full-text