Papers by Keyword: CNG Engine

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Authors: Rong Di Yuan, Cao Bin Zhang
Abstract: Real-time model is one of the key elements in Hardware In Loop (HIL) simulations. A new Crush Natural Gas (CNG) Turbo Engine model and HIL simulation platform are presented in this paper. The platform provides simulations of engine speed, torque, dynamic load, turbo, exhaust gas temperature and emissions conditions. The platform is based on Matlab/Simulink, Labview and can be seamlessly connected with a CNG engine control unit (ECU). Simulation results indicate that platform provide us higher development efficiency as well as lower reduce development expense of ECU.
Authors: Rong Di Yuan, Quan Quan Du
Abstract: A new approach is presented in this paper in which a Crush Natural Gas (CNG) Turbo Engine model based on Mean Value Model and transient dynamics are included. The model could simulate engine speed, torque, dynamic load, electronic throttle, turbo, temperature and emission conditions. The model was downloaded and run in a HIL platform joint with Labview and a CNG engine ECU. Simulation results indicate that it acquires good balance between Real-time response and dynamic accuracy, besides good comprehensive running status parameters including dynamic, mechanic, thermo and combustion. The model made it possible for electronic engineers to begin their works earlier to find solutions for power loss, high working temperature of CNG engine with more flexibility and lower bench test expense.
Authors: Yan Qin, Yu Liu, Yuan Zhi Feng, Guang Yang Liu, Guo Dong Feng
Abstract: We set up one cylinder of CNG engine by using GT-Power software and the compression ratio and the knock are studied. The conclusions are as follows: when the compression ratio increases, the rate of pressure rise of acute burning period increases; The maximum cylinder pressure increases; The maximum temperature decreased slightly and after burning period the temperature increases; The critical knocking compression ratio appears at the full load of 4000rpm conditions; If we only consider it knocking or not, the engine compression ratios can change from 10 to 11.
Authors: Yi Tuan He, Na An
Abstract: The effects of ignition advance angle and excess air ratio on the combustion and emissions characteristics were investigated on a CNG engine at idle conditions. The throttle valve was fully closed. When the parameters were changed, the stepper motor was adjusted automatically to control the engine speed at 800r/min. When the θi is changed from 40 to 10o BTDC, the maximum ITE and the maximum power are observed at λ=1.1. As λ increases, the maximum ITE is corresponding to a greater θi. The COVimep will be increased if the θi is too advanced or too small. When λ is more than 1.3, the COVimep increases obviously. When λ=1.1, NOx emissions get the highest level.
Authors: Xiao Lu, Da Wei Qu, Jian Xi Pang, Ji Fei Lu
Abstract: Experimental study on the combustion and emission performance of turbocharged lean-burned CNG engine by the ignition time. Speed of the engine is 1340r/min,1615r/min,1890r/min,with 25%, 50%,75%,100% load. Results show that when keeping other combustion boundary conditions unchanged, the effect of the ignition time on engine output torque and CH4 is little,the effect changes as speed varies from low speed and load conditions to higher level.However,the effects of ignition time on NOx emissions are huge.With the backward changes of the ignition time,NOx emissions has decreased significantly.
Authors: Jian Xi Pang, Da Wei Qu, Xiao Lu, Guang Yang Liu
Abstract: Experimental research on the effect of excess air ratio on dynamic and emission performance of turbocharged lean-burned CNG engine. The 12 test conditions contain engine speeds of 1300r/min, 1600r/min, and 1900r/min, with 25%, 50%, 75%, 100% load separately. When keeping other combustion boundary conditions unchanged, the excess air ratio has little effect on engine output torque at almost all test conditions, but has obvious effect on CH4 and NOx emission. With the excess air ratio increasing, the emission of CH4 has increased while the NOx emission has decreased significantly. When the λ value is in the range of 1.4-1.45, the emission level is lower.
Authors: Xiao Na Sun, Hong Guang Zhang, Guo Yong Zheng
Abstract: Power performance tests of natural gas engine were carried out using a self-dependent developed electronic injection system and ignition system, and a comparative analysis between the natural gas engine and original gasoline engine was conducted. The result shows that if the gasoline engine is fueled with NG torque of the engine decreases and with the throttle opening increases, the decrease amplitude increases. Developing a suitable electronic ignition system can recover engine torque to some extent. Under the conditions that both throttle opening and rotation speed of the engine are constant, MBT angle increases with the decrease of mixture concentration.
Authors: Shahrul Azmir Osman, Ahmad Jais Alimin, Mohd Yusri Ismail, Koh Wern Hui
Abstract: Diesel engines are widely used in logistics and haulage as vehicular prime movers. In the mechanized and fast-moving forward world of today, the consumption of petroleum products has become an important yardstick of a country’s prosperity. This ever-increasing consumption has led the world to face the twin challenge of energy shortage and environmental deterioration. Natural gas has been one of the highly considered alternative fuels for both spark ignition (S.I) and compressed ignition (C.I.) engines. The advantages and benefits of CNG have made it the preferred choice as alternative fuel in the transportation sector. This present study focused on the effects of retrofitted direct injection C.I. engine with mono-CNG system to its performance and exhaust emissions. The engine speed was varied from 850 rpm to 2500 rpm, with load test conditions of 0Nm, 27.12Nm and 53.23Nm, using an engine dynamometer. Results indicated that CNG has the potential to provide better fuel consumption compared to diesel fuel. Meanwhile, the characteristics of exhaust gas emissions such as smoke opacity and CO2 gave promising results compared to CO, HC and NOX, for diesel combustion.
Authors: Lei Guan, Tian You Wang, Hai Yan Zhang, Zhi Jin Zhang
Abstract: The study on combustion characteristics of different excess air ratios (λ) and ignition timings was conducted on a lean-burn spark-ignition CNG engine, and the corresponding emission characteristics was also analyzed. The results show that the curve of cylinder pressure moves towards TDC, and the CoVimep decreases with the advance of ignition timing. With the excess air ratio increasing, the CoVimep increases while the cylinder pressure decreases firstly, and then increases. The flame development duration increases with the ignition timing advanced, but the rapid flame duration decreases, the total combustion duration basically keep constant, and all of them increase with the increasement of excess air ratio. Best fuel economy was gotten at λ=1.2. With the excess air ratio increasing, the CO and NMHC emissions decrease, the NOx emission firstly reaches to a peak value, which is about 3000ppm at λ=1.2, and then decreases. Both of the THC and CH4 emissions have opposite trends to NOx emission. All the emissions mentioned above increases with the advance of ignition timing.
Authors: Fu Qiang Luo, Fu Shui Xu, Jing Bo Li, Bo Wen Zou, Qing Ying Kang
Abstract: The distribution of temperature and NOX concentration field under different crank angle of a CNG direct-injection engine converted from a four-valve gasoline vehicle engine are calculated by the computation model of the CNG direct-injection engine work process using CFD software. The results show that the temperature field spreads around the center of the spark plug in initial combustion period. The position of maximum temperature in combustion chamber moves from the spark plug to the wall and temperature tends to uniform distribution as the piston goes down along with the spread of flame front and the completion reaction after the flame. Temperature distribution is vital to the generation of NOX which changes along with high-temperature zone. The change principle of quantity of NOX in the cylinder is that at first, the quantity continues increasing, then declines, and finally remains stable. Besides this, the generation amount of NOX increase along with the speed.
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