Combustion Characteristics of Spark Ignition Engine Fuelled by LPG

Author(s):  
M. S. Shehata

Abstract Experimental studies have been carried out for investigating engine performance parameters, cylinder pressure, emissions and engine thermal balance of spark ignition engine (S.I.E.) using either gasoline or Liquefied Petroleum Gases (LPG) as a fuel at maximum brake torque (MBT) ignition timing. MBT ignition timing for LPG is found to be 2 to 10 degrees crank angle more advance than for gasoline. Maximum cylinder pressure locations for gasoline and LPG are shifted towards top dead center (TDC) with increase engine speed. At low engine speed, maximum cylinder pressure for gasoline fuel is higher than for LPG fuel. At high engine speeds maximum cylinder pressure for LPG is nearly the same as for gasoline. Maximum pressure for ignition timing 35 crank angle (CA) before top dead center (BTDC) is greater than for 45 and 25 CA respectively. Engine produces more brake power with gasoline than with LPG. Engine brake thermal efficiency (ηbth) and volumetric efficiency (ηv) with LPG is less than for gasoline. When S.I.E converted from gasoline to LPG the loss in maximum power is nearly 14% and the loss in maximum efficiency is nearly 8%. UHC and CO concentrations for LPG are nearly one-tenth of that produced by gasoline at the same ignition timing and the same engine speed. For low engine speed exhaust and oil temperatures for gasoline and LPG increase with increase engine speed but for high engine speed exhaust and oil temperature decreases with increase engine speed. For gasoline and LPG cooling water temperature decreases with increase engine speed. Lubricating oil and cooling water temperatures for gasoline and LPG increase with increase ignition timing BTDC but exhaust gas temperature decreases with increase ignition timing. LPG has higher exhausted gas temperature than gasoline but gasoline has higher oil temperature than LPG. At different ignition timing exhaust loss for LPG is greater than for gasoline but cooling water loss for gasoline is greater than for LPG.

Author(s):  
Xin Wang ◽  
Amir Khameneian ◽  
Paul Dice ◽  
Bo Chen ◽  
Mahdi Shahbakhti ◽  
...  

Abstract Combustion phasing, which can be defined as the crank angle of fifty percent mass fraction burned (CA50), is one of the most important parameters affecting engine efficiency, torque output, and emissions. In homogeneous spark-ignition (SI) engines, ignition timing control algorithms are typically map-based with several multipliers, which requires significant calibration efforts. This work presents a framework of model-based ignition timing prediction using a computationally efficient control-oriented combustion model for the purpose of real-time combustion phasing control. Burn duration from ignition timing to CA50 (ΔθIGN-CA50) on an individual cylinder cycle-by-cycle basis is predicted by the combustion model developed in this work. The model is based on the physics of turbulent flame propagation in SI engines and contains the most important control parameters, including ignition timing, variable valve timing, air-fuel ratio, and engine load mostly affected by combination of the throttle opening position and the previous three parameters. With 64 test points used for model calibration, the developed combustion model is shown to cover wide engine operating conditions, thereby significantly reducing the calibration effort. A Root Mean Square Error (RMSE) of 1.7 Crank Angle Degrees (CAD) and correlation coefficient (R2) of 0.95 illustrates the accuracy of the calibrated model. On-road vehicle testing data is used to evaluate the performance of the developed model-based burn duration and ignition timing algorithm. When comparing the model predicted burn duration and ignition timing with experimental data, 83% of the prediction error falls within ±3 CAD.


2017 ◽  
Vol 20 (K6) ◽  
pp. 79-86
Author(s):  
Quoc Dang Tran

This article shows an investigated research on Compressed Natural Gas (CNG) engine with a port injection when varying ignition timing. The obtained results from simulating study have indicated that both of brake thermal efficiency and torque have a similar trend when varying ignition timing. The effect of ignition timing on the value of brake thermal efficiency is stronger in comparison with torque, however, the increase in engine speed or lambda value have to adjust the ignition timing more early. To reach the maximum break torque at each engine speed, the ignition timing should be adjusted IT = 14 - 32 bTDC, and this is also basic value to design the ignition timing system using CNG engine with port injection.


Author(s):  
Karthik Nithyanandan ◽  
Chia-fon F. Lee ◽  
Han Wu ◽  
Jiaxiang Zhang

Acetone-Butanol-Ethanol (ABE), an intermediate product in the ABE fermentation process for producing bio-butanol, is considered a promising alternative fuel because it not only preserves the advantages of oxygenated fuels which typically emit fewer pollutants, but also lowers the cost of fuel recovery for each individual component during fermentation. An experiment was conducted using a Ford single-cylinder spark-ignition (SI) research engine to investigate the potential of ABE as an SI engine fuel. Blends of pure gasoline and ABE, ranging from 0% to 80% vol. ABE, were created and the performance and emission characteristics were compared with pure gasoline as the baseline. Measurements of brake torque and exhaust gas temperature along with in-cylinder pressure traces were used to study the performance of the engine and measurements of emissions of unburned hydrocarbons, carbon monoxide, and nitrogen oxides were used to compare the fuels in terms of combustion byproducts. Experiments were performed at a constant engine speed and a comparison was made on the basis of similar power output (Brake Mean Effective Pressure (BMEP)). In-cylinder pressure data showed that the peak pressure of all the blends was slightly lower than that of gasoline, except for ABE80 which showed a slightly higher and advanced peak relative to gasoline. ABE showed an increase in brake specific fuel consumption (BSFC); while exhaust gas temperature and nitrogen oxide measurements show that ABE combusts at a lower peak temperature. The emissions of unburned hydrocarbons were higher compared to those of gasoline but the CO emissions were lower. Of particular interest is the combined effect of the higher laminar flame speed (LFS) and higher latent heat of vaporization of ABE fuels on the combustion process.


2011 ◽  
Vol 2011 (0) ◽  
pp. 253-254
Author(s):  
Noboru Hieda ◽  
Hiroshi Enomoto ◽  
Kosuke Nishioka ◽  
Yuta Hayashi ◽  
Xuan Khoa Nguyen

Author(s):  
V. Matham ◽  
K. Majmudar ◽  
K. Aung

The use of alternative fuels such as natural gas (methane) in spark-ignition (SI) engines is beneficial to the environment as it reduces emissions of pollutants such as NOx from these engines with slight penalty on the performance. This paper investigated the use of methane and hydrogen/methane mixtures in an SI engine by numerical simulations. The numerical simulations were based on the models of finite heat release, cylinder heat transfer, pumping losses, and friction losses. Simulations were carried out to evaluate the effects of compression ratio, equivalence ratio, ignition timing, and engine speed on the performance of the SI engine. The results showed that the current model could satisfactorily predict the performance of an SI engine fueled by gaseous fuels.


Author(s):  
Pin Zeng ◽  
Robert G. Prucka ◽  
Zoran S. Filipi ◽  
Dennis N. Assanis

This paper proposes a technique for reconstructing the cylinder pressure traces of a spark-ignition engine based on three inputs: spark-timing, speed and load. This method is an extension of previous work for reconstructing cylinder pressure in a heavy-duty diesel engine [1]. The previous study utilized only two inputs for cylinder pressure reconstruction, e.g. engine speed and load, hence implying optimal combustion phasing. The new method adds one more input to allow reconstruction of pressure traces from cycles with combustion phasing altered based on emissions or knock constraints. The method was applied to a 4-cylinder, 2.4-liter DaimlerChrysler gasoline engine. Comparisons between measured and reconstructed cylinder pressure traces demonstrate that the method is applicable over the majority of the gasoline engine operating range. Reconstructed cylinder pressure traces have also been used to carry out engine heat transfer and heat release analyses. Problems associated with the application of this method to gasoline engine are also discussed.


Author(s):  
J R Sodré

Gas chromatography tests have been applied to the exhaust gases of a spark ignition engine to determine the concentration of unburned fuel among the total hydrocarbons. The contribution of unburned fuel was determined with variation in several engine parameters. The fuel tested was isooctane. The varied parameters were the air-fuel ratio, engine speed, ignition timing, compression ratio and coolant and lubricant temperature. The results have shown that the unburned fuel is responsible for most of the HC emitted, 50-73 per cent, depending on the engine working conditions. Methane, acetylene, ethylene, ethane, propylene and isobutylene were also analysed, as well as isooctane. The total contribution of the lighter species remained practically unaltered when the parameters were varied, though their individual concentrations did change. Thus, the unburned HC was seen to determine all trends of exhaust hydrocarbons.


2014 ◽  
Vol 984-985 ◽  
pp. 957-961
Author(s):  
Vijayashree ◽  
P. Tamil Porai ◽  
N.V. Mahalakshmi ◽  
V. Ganesan

This paper presents the modeling of in-cylinder pressure variation of a four-stroke single cylinder spark ignition engine. It uses instantaneous properties of working fluid, viz., gasoline to calculate heat release rates, needed to quantify combustion development. Cylinder pressure variation with respect to either volume or crank angle gives valuable information about the combustion process. The analysis of the pressure – volume or pressure-theta data of a engine cycle is a classical tool for engine studies. This paper aims at demonstrating the modeling of pressure variation as a function of crank angle as well as volume with the help of MATLAB program developed for this purpose. Towards this end, Woschni heat release model is used for the combustion process. The important parameter, viz., peak pressure for different compression ratios are used in the analysis. Predicted results are compared with experimental values obtained for a typical compression ratio of 8.3.


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