Improved model for the analysis of the Heat Release Rate (HRR) in Compression Ignition (CI) engines

The homogeneous charge compression ignition (HCCI) combustion fueled by dimethyl ether (DME) and compressed natural gas (CNG) was investigated. The experimental work was carried out on a single-cylinder diesel engine. The results show that adjusting the proportions of DME and CNG is an effective technique for controlling HCCI combustion and extending the HCCI operating range. The combustion process of HCCI with dual fuel is characterized by a distinctive two-stage heat release process. As CNG flow rate increases, the magnitude of peak cylinder pressure and the peak heat release rate in the second stage goes up. As DME flow rate increases, the peak cylinder pressure, heat release rate, and NOx emissions increase while THC and CO emissions decrease.

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An experimental study of the dual-fuel performance of a small compression ignition diesel engine operating with three gaseous fuels

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

10.1243/09544070jauto458 ◽

2007 ◽

Vol 221 (8) ◽

pp. 943-956 ◽

Cited By ~ 27

Author(s):

J Stewart ◽

A Clarke ◽

R Chen

Keyword(s):

Heat Release ◽

Heat Release Rate ◽

Release Rate ◽

High Speed ◽

Direct Injection ◽

Specific Energy Consumption ◽

Dual Fuel ◽

Compression Ignition ◽

Gaseous Fuels ◽

Ci Engine

A dual-fuel engine is a compression ignition (CI) engine where the primary gaseous fuel source is premixed with air as it enters the combustion chamber. This homogenous mixture is ignited by a small quantity of diesel, the ‘pilot’, that is injected towards the end of the compression stroke. In the present study, a direct-injection CI engine, was fuelled with three different gaseous fuels: methane, propane, and butane. The engine performance at various gaseous concentrations was recorded at 1500 r/min and quarter, half, and three-quarters relative to full a load of 18.7 kW. In order to investigate the combustion performance, a novel three-zone heat release rate analysis was applied to the data. The resulting heat release rate data are used to aid understanding of the performance characteristics of the engine in dual-fuel mode. Data are presented for the heat release rates, effects of engine load and speed, brake specific energy consumption of the engine, and combustion phasing of the three different primary gaseous fuels. Methane permitted the maximum energy substitution, relative to diesel, and yielded the most significant reductions in CO2. However, propane also had significant reductions in CO2 but had an increased diffusional combustion stage which may lend itself to the modern high-speed direct-injection engine.

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Influence of hydrogen as a fuel additive on combustion and emissions characteristics of a free piston engine

Thermal Science ◽

10.2298/tsci181211071a ◽

2020 ◽

Vol 24 (1 Part A) ◽

pp. 87-99

Author(s):

Mohammad Alrbai ◽

Bashar Qawasmeh ◽

Sameer Al-Dahidi ◽

Osama Ayadi

Keyword(s):

Heat Release ◽

Heat Release Rate ◽

Release Rate ◽

Ignition Delay ◽

Combustion Characteristics ◽

Fuel Additive ◽

Compression Ignition ◽

Piston Engine ◽

Free Piston ◽

Free Piston Engine

It has been shown that using fuel additives play an important role in enhancing the combustion characteristics in terms of efficiency and emissions. In addition, free piston engines have shown capable in reducing energy losses and presenting more efficient and reliable engines. In this context, the objective of the present work is to investigate the effect of using hydrogen as a fuel additive in natural gas homogeneous charge compression ignition free piston engine. To this aim, two models have been iteratively coupled: the combustion model that is used to calculate the heat release of the combustion and the scavenging model that is employed to determine the in-cylinder mixture state after scavenging in terms of its homogeneity and species mass fractions and to obtain the finial pressure and temperature of the in-cylinder mixture. In the former model, the 0-D approach through Cantera toolkit has been considered due to the fact that homogeneous charge compression ignition combustion is very rapid and the fuel-air mixture is well-homogenous, whereas in the latter model, 3-D-CFD approach through AN-SYS FLUENT software is considered to ensure precise calculations of the species exchange at the end of each engine cycle. The effect of hydrogen as a fuel additive has been quantified in terms of the combustion characteristics (e. g., ignition delay, heat release rate, engine overall efficiency and emissions, etc.). It has been shown that hydrogen addition reduces ignition delay time, decreases the in-cylinder peak pressure, while allowing the engine to operate with higher mechanical efficiency as it has high heat release rate, increases the NOx emission levels of the engine, but decreases the CO levels

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Study On Design Method of Combustion Reference Values for Model-Based Control of Advanced Diesel Engine

Journal of Engineering for Gas Turbines and Power ◽

10.1115/1.4052499 ◽

2021 ◽

Author(s):

Jihoon Kim ◽

Yudai Yamasaki

Keyword(s):

Heat Release ◽

Control Systems ◽

Reference Values ◽

Heat Release Rate ◽

Release Rate ◽

Design Method ◽

Operating Conditions ◽

Compression Ignition ◽

Model Based Control ◽

Model Based

Abstract Model-based control systems are drawing attention in relation to implementing next-generation combustion technologies with high thermal efficiency and low emissions, such as homogeneous charge compression ignition (HCCI) and premixed charge compression ignition (PCCI) combustion, which have low robustness. A model-based control system derives control inputs according to reference values and operating conditions during every cycle, and has potential to replace the conventional control map, which requires a large number of experiments. However, model-based control for engines requires reference values for combustion, such as heat release rate peak timing and heat release rate peak value; such values represent the combustion state. Therefore, the reference for the transient condition is important for utilizing the benefit of model-based control systems, given that such systems derive control outputs cycle by cycle. In this study, design method for the combustion reference values for the transient operating condition is described for advanced diesel combustion, which uses premixed compression ignition combustion shows multiple heat releases. Specifically, a method utilizing future operating conditions in consideration of the driving characteristics is proposed and compared in engine control experiments. The proposed method was evaluated under certain part of worldwide harmonized light vehicles test cycles (WLTC) mode considering real road conditions. Results showed that designing the combustion reference values for transient operation by considering future operating conditions is effective to ensure advanced combustion, and such method has the potential to consider the driving characteristics.

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Diethyl Ether as an Ignition Enhancer for Naphtha Creating a Drop in Fuel for Diesel

ASME 2016 Internal Combustion Engine Fall Technical Conference ◽

10.1115/icef2016-9324 ◽

2016 ◽

Cited By ~ 1

Author(s):

R. Vallinayagam ◽

S. Vedharaj ◽

S. Mani Sarathy ◽

Robert W. Dibble

Keyword(s):

Heat Release ◽

Heat Release Rate ◽

Release Rate ◽

Ignition Delay ◽

Cetane Number ◽

Cylinder Pressure ◽

Auto Ignition ◽

Peak Heat Release Rate ◽

Ignition Characteristics ◽

Ci Engines

Direct use of naphtha in compression ignition (CI) engines is not advisable because its lower cetane number negatively impacts the auto ignition process. However, engine or fuel modifications can be made to operate naphtha in CI engines. Enhancing a fuel’s auto ignition characteristics presents an opportunity to use low cetane fuel, naphtha, in CI engines. In this research, Di-ethyl ether (DEE) derived from ethanol is used as an ignition enhancer for light naphtha. With this fuel modification, a “drop-in” fuel that is interchangeable with existing diesel fuel has been created. The ignition characteristics of DEE blended naphtha were studied in an ignition quality tester (IQT); the measured ignition delay time (IDT) for pure naphtha was 6.9 ms. When DEE was added to naphtha, IDT decreased and D30 (30% DEE + 70% naphtha) showed comparable IDT with US NO.2 diesel. The derived cetane number (DCN) of naphtha, D10 (10% DEE + 90% naphtha), D20% DEE + 80% naphtha) and D30 were measured to be 31, 37, 40 and 49, respectively. The addition of 30% DEE in naphtha achieved a DCN equivalent to US NO.2 diesel. Subsequent experiments in a CI engine exhibited longer ignition delay for naphtha compared to diesel. The peak in-cylinder pressure is higher for naphtha than diesel and other tested fuels. When DEE was added to naphtha, the ignition delay shortened and peak in-cylinder pressure is reduced. A 3.7% increase in peak in-cylinder pressure was observed for naphtha compared to US NO.2 diesel, while D30 showed comparable results with diesel. The pressure rise rate dropped with the addition of DEE to naphtha, thereby reducing the ringing intensity. Naphtha exhibited a peak heat release rate of 280 kJ/m3deg, while D30 showed a comparable peak heat release rate to US NO.2 diesel. The amount of energy released during the premixed combustion phase decreased with the increase of DEE in naphtha. Thus, this study demonstrates the suitability of DEE blended naphtha mixtures as a “drop-in” replacement fuel for diesel.

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