Investigations on The Influence of Ignition Voltage, Higher Compression Ratio and Piston Crown Geometry on the Performance of Compressed Natural Gas Engines

2008 ◽  
Author(s):  
Rajesh C. Iyer ◽  
Mallikarjun Vaggar ◽  
T. R. Seetharam ◽  
Salim Abbasbhai Channiwala
Keyword(s):  
Natural Gas ◽  
Compression Ratio ◽  
Compressed Natural Gas ◽  
Natural Gas Engines ◽  
Ignition Voltage ◽  
Piston Crown

scholarly journals Combustion and energy distribution of hydrogen-enriched compressed natural gas engines with low heat rejection based on Atkinson cycle

2019 ◽  
Vol 11 (1) ◽  
pp. 168781401881958 ◽  
Author(s):  
Yang Liu ◽  
Yituan He ◽  
Cuijie Han ◽  
Chenheng Yuan
Keyword(s):  
Natural Gas ◽  
Heat Loss ◽  
Compression Ratio ◽  
Thermal Efficiency ◽  
High Compression Ratio ◽  
Compressed Natural Gas ◽  
Heat Rejection ◽  
Natural Gas Engines ◽  
High Compression ◽  
Atkinson Cycle

In order to reduce the heat loss and improve the indicated thermal efficiency of hydrogen-enriched compressed natural gas engines, this article presents a combination of Atkinson cycle with high compression ratio and low heat rejection on the hydrogen-enriched compressed natural gas prototype engine with 55% hydrogen blend. The combustion characteristics and energy distribution of the prototype and modified engines were investigated by simulation, and the conclusions are as follows: the pressure and temperature of modified engines are higher than those of the prototype during the combustion process. Compared with the prototype, the modified engines present lower peak heat release rate, but faster combustion after ignition, and their CA50 are closer to top dead center. Although the high compression ratio engine with Atkinson cycle generates more heat loss, its indicated thermal efficiency still increases by 0.6% with the decrease in the exhaust energy. Furthermore, the high compression ratio engine with low heat rejection and Atkinson cycle combines the advantages of low heat loss and relatively longer expansion stroke, so its heat loss reduces obviously, and 61.6% of the saved energy from low heat rejection and Atkinson cycle can be converted into indicated work that indicates a 4.5% improvement in indicated thermal efficiency over the prototype, which makes it perform better in terms of power and fuel economy simultaneously.

scholarly journals Experimental Study of Ceramic Coated Piston Crown for Compressed Natural Gas Direct Injection Engines

2013 ◽  
Vol 68 ◽  
pp. 505-511 ◽  
Author(s):  
Helmisyah Ahmad Jalaludin ◽  
Shahrir Abdullah ◽  
Mariyam Jameelah Ghazali ◽  
Bulan Abdullah ◽  
Nik Rosli Abdullah
Keyword(s):  
Experimental Study ◽  
Natural Gas ◽  
Direct Injection ◽  
Compressed Natural Gas ◽  
Direct Injection Engines ◽  
Piston Crown

scholarly journals Parametric Knocking Performance Investigation of Spark Ignition Natural Gas Engines and Dual Fuel Engines

2020 ◽  
Vol 8 (6) ◽  
pp. 459 ◽  
Author(s):  
La Xiang ◽  
Gerasimos Theotokatos ◽  
Haining Cui ◽  
Keda Xu ◽  
Hongkai Ben ◽  
...  
Keyword(s):  
Natural Gas ◽  
Compression Ratio ◽  
Engine Performance ◽  
Spark Ignition ◽  
Combustion Model ◽  
Dual Fuel ◽  
Ignition Timing ◽  
Natural Gas Engines ◽  
Study Results ◽  
Pilot Fuel

Both spark ignition (SI) natural gas engines and compression ignition (CI) dual fuel (DF) engines suffer from knocking when the unburnt mixture ignites spontaneously prior to the flame front arrival. In this study, a parametric investigation is performed on the knocking performance of these two engine types by using the GT-Power software. An SI natural gas engine and a DF engine are modelled by employing a two-zone zero-dimensional combustion model, which uses Wiebe function to determine the combustion rate and provides adequate prediction of the unburnt zone temperature, which is crucial for the knocking prediction. The developed models are validated against experimentally measured parameters and are subsequently used for performing parametric investigations. The derived results are analysed to quantify the effect of the compression ratio, air-fuel equivalence ratio and ignition timing on both engines as well as the effect of pilot fuel energy proportion on the DF engine. The results demonstrate that the compression ratio of the investigated SI and DF engines must be limited to 11 and 16.5, respectively, for avoiding knocking occurrence. The ignition timing for the SI and the DF engines must be controlled after −38°CA and 3°CA, respectively. A higher pilot fuel energy proportion between 5% and 15% results in increasing the knocking tendency and intensity for the DF Engine at high loads. This study results in better insights on the impacts of the investigated engine design and operating settings for natural gas (NG)-fuelled engines, thus it can provide useful support for obtaining the optimal settings targeting a desired combustion behaviour and engine performance while attenuating the knocking tendency.

scholarly journals Stochastic Air-Fuel Ratio Control of Compressed Natural Gas Engines Using State Observer

2020 ◽  
Vol 2020 ◽  
pp. 1-8
Author(s):  
Jun Yang ◽  
Jian Wang ◽  
Xuesheng Zhou ◽  
Yanxiao Li
Keyword(s):  
Natural Gas ◽  
State Observer ◽  
Disturbance Attenuation ◽  
Accuracy Control ◽  
Compressed Natural Gas ◽  
Natural Gas Engines ◽  
Fuel Ratio ◽  
Cng Engine ◽  
Residual Gas ◽  
Engine Dynamic

In this paper, the air-fuel ratio regulation problem of compressed natural gas (CNG) engines considering stochastic L2 disturbance attenuation is researched. A state observer is designed to overcome the unmeasurability of the total air mass and total fuel mass in the cylinder, since the residual air and residual fuel that are included in the residual gas are unmeasured and the residual gas reflects stochasticity. With the proposed state observer, a stochastic robust air-fuel ratio regulator is proposed by using a CNG engine dynamic model to attenuate the uncertain cyclic fluctuation of the fresh air, and the augmented closed-loop system is mean-square stable. A validation of the proposed stochastic robust air-fuel ratio regulator is carried out by the numerical simulation of two working conditions. The accuracy control of the air-fuel ratio is realized by the proposed stochastic robust air-fuel ratio regulator, which in turn leads to an improvement in fuel economy and emission performance of the CNG engines.

Effect of Thermal Barrier Coating on Piston Crown for Compressed Natural Gas with Direct Injection Engine

2011 ◽  
Vol 52-54 ◽  
pp. 1830-1835 ◽  
Author(s):  
A.J. Helmisyah ◽  
Shahrir Abdullah ◽  
Mariyam Jameelah Ghazali
Keyword(s):  
Heat Flux ◽  
High Temperature ◽  
Natural Gas ◽  
Thermal Stresses ◽  
Direct Injection ◽  
Thermal Barrier ◽  
Compressed Natural Gas ◽  
Piston Crown ◽  
Barrier Coating ◽  
Temperature And Pressure

The top land of a piston normally known as the piston crown is an engine part that is continuously exposed to extreme temperature and pressure during combustion. For a compression ratio level, the compressed natural gas with a direct injection system (CNGDI) typically uses a range of compression ratio between gasoline and diesel engines, producing extremely high temperature and pressure which lead to high thermal stresses. Consequently, the piston crown is exposed to direct combustion due to the vertical movement of the piston, leading to various possible damages of thermal stresses. In contrast to a petrol fuelled internal combustion engine, natural gas combustion creates a dry condition in the combustion chamber, inducing cooling difficulties in the engine. Without good heat transfer, the piston crown materials will soon fail to withstand high temperature and operate effectively. Alternatively, any sort of insulation inside the combustion chamber such as applying ceramic coatings may protect the piston crown surface and affect the overall combustion process, as well as improving the engine performance and the exhaust emissions. By reducing the heat loss of a cylinder bore, a higher thermal efficiency of an engine can also be improved by applying a surface thermal insulation, namely; thermal barrier coating (TBC). Thus, in this study, a ceramic based TBC, yttria partially stabilised zirconia (YPSZ) coating was used to compare with conventional tin coated (Na2SnO3) and uncoated piston crown in terms of heat concentration. Moreover, a set of average value of combustion temperature of a CNGDI engine was selected. Detailed analyses using a finite element analysis (FEA) technique was utilised in order to determine the location of hotspots via distribution profiles of temperature. It was noted that the maximum heat flux of the uncoated piston crown was much higher than that of tin coated and YPSZ coated piston crown. Heat flux value reached about 62% of decrement due to lower conductivity levels of piston crown.

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