Effect of specific heat ratio on heat release analysis in a spark ignition engine

Measurements of the radiant emission in the near infrared have been obtained in a spark-ignition engine over a wide range of operating conditions. The system includes an in-cylinder optical sensor and associated detector. Prior work has shown correlations between the measured radiance and pressure quantities such as maximum cylinder pressure, crank angle of maximum pressure, and Indicated Mean Effective Pressure. Here are presented comparisons between the radiant intensity and a simplified model of the radiation emission, which demonstrate that the measured intensity is a function of the mass-burn fraction, mean burned-gas temperature, and the exposed combustion-chamber surface area. Further simplification leads to the conclusion that the time of the maximum rate of change of radiant intensity is the same as for the maximum heat-release rate, leading to the possibility of feedback control of spark timing. In addition, the magnitudes of the maximum rate of change of radiant emission and maximum heat-release rate have a linear relationship over a range of different operating conditions.

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Numerical Investigation of Fuel Property Effects on Mixed-Mode Combustion in a Spark-Ignition Engine

ASME 2019 Internal Combustion Engine Division Fall Technical Conference ◽

10.1115/icef2019-7265 ◽

2019 ◽

Cited By ~ 1

Author(s):

Chao Xu ◽

Pinaki Pal ◽

Xiao Ren ◽

Sibendu Som ◽

Magnus Sjöberg ◽

...

Keyword(s):

Heat Release ◽

Flame Propagation ◽

Heat Release Rate ◽

Release Rate ◽

Octane Number ◽

Mixed Mode ◽

Spark Ignition ◽

Spark Ignition Engine ◽

Chemical Effect ◽

Auto Ignition

Abstract In the present study, mixed-mode combustion of an E30 fuel in a direct-injection spark-ignition engine is numerically investigated at a fuel-lean operating condition using multidimensional computational fluid dynamics (CFD). A fuel surrogate matching Research Octane Number (RON) and Motor Octane Number (MON) of E30 is first developed using neural network based non-linear regression model. To enable efficient 3D engine simulations, a 164-species skeletal reaction mechanism incorporating NOx chemistry is reduced from a detailed chemical kinetic model. A hybrid approach that incorporates the G-equation model for tracking turbulent flame front, and the multi-zone well-stirred reactor model for predicting auto-ignition in the end gas, is employed to account for turbulent combustion interactions in the engine cylinder. Predicted in-cylinder pressure and heat release rate traces agree well with experimental measurements. The proposed modelling approach also captures moderated cyclic variability. Two different types of combustion cycles, corresponding to purely deflagrative and mixed-mode combustion, are observed. In contrast to the purely deflagrative cycles, mixed-mode combustion cycles feature early flame propagation followed by end-gas auto-ignition, leading to two distinctive peaks in heat release rate traces. The positive correlation between mixed-mode combustion cycles and early flame propagation is well captured by simulations. With the validated numerical setup, effects of NOx chemistry on mixed-mode combustion predictions are investigated. NOx chemistry is found to promote auto-ignition through residual gas recirculation, while the deflagrative flame propagation phase remains largely unaffected. Local sensitivity analysis is then performed to understand effects of physical and chemical properties of the fuel, i.e., heat of evaporation (HoV) and laminar flame speed (SL). An increased HoV tends to suppress end-gas auto-ignition due to increased vaporization cooling, while the impact of HoV on flame propagation is insignificant. In contrast, an increased SL is found to significantly promote both flame propagation and auto-ignition. The promoting effect of SL on auto-ignition is not a direct chemical effect; it is rather caused by an advancement of the combustion phasing, which increases compression heating of the end gas.

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Estimating Heat-Release and Mass-of-Mixture Burned from Spark-Ignition Engine Pressure Data

Combustion Science and Technology ◽

10.1080/00102208708947049 ◽

1987 ◽

Vol 54 (1-6) ◽

pp. 133-143 ◽

Cited By ~ 111

Author(s):

KWANG MIN CHUN ◽

JOHN B. HEYWOOD

Keyword(s):

Heat Release ◽

Spark Ignition ◽

Spark Ignition Engine ◽

Pressure Data

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Factors Determining Antiknocking Properties of Gaseous Fuels in Spark-Ignition Gas Engines

Journal of Engineering for Gas Turbines and Power ◽

10.1115/1.4033063 ◽

2016 ◽

Vol 138 (10) ◽

Author(s):

Hiroki Tanaka ◽

Kazunobu Kobayashi ◽

Takahiro Sako ◽

Kazunari Kuwahara ◽

Hiroshi Kawanabe ◽

...

Keyword(s):

Specific Heat ◽

Burning Velocity ◽

Spark Ignition ◽

Primary Component ◽

Engine Operation ◽

Specific Heat Ratio ◽

Gaseous Fuels ◽

Fuel Ratio ◽

Secondary Fuel ◽

High Specific Heat

The factors affecting knock resistance of fuels, including hydrogen (H2), ethane (C2H6), propane (C3H8), normal butane (n-C4H10), and iso-butane (i-C4H10), were determined using modeling and engine operation tests with spark-ignition gas engines. The results of zero-dimensional detailed chemical kinetic computations indicated that H2 had the longest ignition delay time of these gaseous fuels. Thus, H2 possessed the lowest ignitability. The results of engine operation tests indicated that H2 was the fuel most likely to result in knocking. The use of H2 as the fuel produced a temperature profile of the unburned gas compressed by the piston and flame front that was higher than that of the other fuels due to the high-specific heat ratio and burning velocity of H2. The relation between knock resistance and secondary fuel ratio in methane-based fuel blends also was investigated using methane (CH4) as the primary component, and H2, C2H6, C3H8, n-C4H10, or i-C4H10 as the secondary components. When the secondary fuel ratio was small, the CH4/H2 blend possessed the lowest knocking tendency. But as the secondary fuel ratio increased, the CH4/H2 mixture possessed a greater tendency to knock than CH4/C2H6 due to the high-specific heat ratio and burning velocity of H2. These results indicate that the knocking that can occur with gaseous fuels is not only dependent on the ignitability of the fuel but it also the specific heat ratio and burning velocity.

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Factors Determining Anti-Knocking Properties of Gaseous Fuels in Spark Ignition Gas Engines

Volume 1: Large Bore Engines; Fuels; Advanced Combustion ◽

10.1115/icef2015-1079 ◽

2015 ◽

Author(s):

Hiroki Tanaka ◽

Kazunobu Kobayashi ◽

Takahiro Sako ◽

Kazunari Kuwahara ◽

Hiroshi Kawanabe ◽

...

Keyword(s):

Specific Heat ◽

Burning Velocity ◽

Spark Ignition ◽

Primary Component ◽

Engine Operation ◽

Specific Heat Ratio ◽

Gaseous Fuels ◽

Fuel Ratio ◽

Secondary Fuel ◽

High Specific Heat

The factors affecting knock resistance of fuels, including hydrogen (H2), ethane (C2H6), propane (C3H8), normal butane (n-C4H10), and iso-butane (i-C4H10), were determined using modeling and engine operation tests with spark-ignition gas engines. The results of zero-dimensional detailed chemical kinetic computations indicated that H2 had the longest ignition delay time of these gaseous fuels. Thus, H2 possessed the lowest ignitability. Results of engine operation tests indicated that H2 was the fuel most likely to result in knocking. The use of H2 as the fuel produced a temperature profile of the unburned gas compressed by the piston and flame front that was higher than that of the other fuels due to the high specific heat ratio and burning velocity of H2. The relation between knock resistance and secondary fuel ratio in methane-based fuel blends also was investigated using methane (CH4) as the primary component, and H2, C2H6, C3H8, n-C4H10, or i-C4H10 as the secondary components. When the secondary fuel ratio was small, the CH4/H2 blend possessed the lowest knocking tendency. But as the secondary fuel ratio increased, the CH4/H2 mixture possessed a greater tendency to knock than did CH4/C2H6 due to the high specific heat ratio and burning velocity of H2. These results indicate that the knocking that can occur with gaseous fuels is not only dependent on the ignitability of the fuel, but it also the specific heat ratio and burning velocity.

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An Experimental Study of Cyclic Variations in a Lean Burn Natural Gas Fuelled Spark Ignition Engine

Design and Control of Diesel and Natural Gas Engines for Industrial and Rail Transportation Applications ◽

10.1115/icef2003-0772 ◽

2003 ◽

Author(s):

A. Ramesh ◽

Mohand Tazerout ◽

Olivier Le Corre

Keyword(s):

Natural Gas ◽

Heat Release ◽

Pressure Rise ◽

Spark Ignition ◽

Spark Ignition Engine ◽

High Rate ◽

Lean Burn ◽

Complete Combustion ◽

Average Value ◽

Indicated Mean Effective Pressure

This work deals with the nature of cycle by cycle variations in a single cylinder, lean burn, natural gas fuelled spark ignition engine operated at a constant speed of 1500 rev/min under variable equivalence ratio, fixed throttle conditions. Cycle by cycle variations in important parameters like indicated mean effective pressure (IMEP), peak pressure, rate of pressure rise and heat release characteristics were studied. At the lean misfire limit there was a drastic increase in combustion duration. With mixtures leaner than the lean limit, good cycles generally followed poor cycles. However, the vice versa was not true. Cycles that had a high initial heat release rate lead to more complete combustion. A high rate of pressure rise led to a high IMEP. The IMEP of cycles versus their frequency of occurrence was symmetric about the average value when the combustion was good.

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