Autoignition of Isooctane beyond RON and MON Conditions

Masurier, Jean-Baptiste; Waqas, Muhammad; Sarathy, S. Mani; Johansson, Bengt

doi:10.4271/2018-01-1254

Cited by 8 publications

(5 citation statements)

References 25 publications

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“…Since SOC is controlled by chemical kinetics, it is very sensitive to slight variations of the incylinder thermal conditions. As a result, predicting the start of combustion is very difficult, as well as keeping the combustion process between the allowable limits for misfire and knocking [12][13][14].…”

Section: Introductionmentioning

confidence: 99%

Injection Pattern Investigation for Gasoline Partially Premixed Combustion Analysis

Stola¹,

Ravaglioli

Silvagni

et al. 2019

SAE Technical Paper Series

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Nowadays, compression-ignited engines are considered the most efficient and reliable technology for automotive applications. However, mainly due to the current emission regulations, that require increasingly stringent reductions of NOx and particulate matter, the use of diesel-like fuels is becoming a critical issue. For this reason, a large amount of research and experimentation is being carried out to investigate innovative combustion techniques suitable to simultaneously mitigate the production of NOx and soot, while improving engine efficiency. In this scenario, the combined use of compression-ignited engines and gasoline-like fuels proved to be very promising, especially in case the fuel is directly-injected in the combustion chamber at high pressure. The presented study analyzes the combustion process produced by the direct injection of small amounts of gasoline in a compression-ignited light-duty engine. The engine under investigation has been modified to guarantee a stable engine operation over its whole operating range, that is achieved controlling boost pressure and temperature, together with the design of the injection pattern. Experimental tests have been performed to highlight the impact of several control variables on the combustion effectiveness, i.e. on combustion efficiency and ignition delay. To identify the main mechanisms which impact the start of the combustion process and the sensitivity to the variation of the main control parameters, several tests have been run, directly-injecting constant amounts of gasoline in a compression ignited engine. These tests have been performed changing intake pressure and temperature (when suitable to maintain combustion stability), fuel pressure and injection timing within the cycle.

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Section: Introductionmentioning

confidence: 99%

Injection Pattern Investigation for Gasoline Partially Premixed Combustion Analysis

Stola¹,

Ravaglioli

Silvagni

et al. 2019

SAE Technical Paper Series

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“…Therefore, no negative contribution in terms of energy spent on the volumetric compressor needs to be considered in the evaluation of combustion efficiency. Besides boost pressure, many works show that intake temperature also plays a crucial role in gasoline PPC stability [20,21,22]. For these reasons, to accurately control the intake air temperature, a high-temperature diathermic oil thermoregulation unit (TEMPCO T-REG HCE 609/15-O) has been installed midway between the centrifugal compressor and the intake manifold.…”

Section: Methodsmentioning

confidence: 99%

Investigation of Gasoline Partially Premixed Combustion with External Exhaust Gas Recirculation

Ravaglioli¹,

Ponti²,

Silvagni³

et al. 2021

SAE Int. J. Engines

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The stringent emission regulations for Internal Combustion Engines (ICEs) spawned a great amount of research in the field of innovative combustion approaches characterized by high efficiency and low emissions. Previous research demonstrate that such promising techniques, named Low-Temperature Combustion (LTC), combine the benefits of Compression Ignition (CI) engines, such as high compression ratio and unthrottled lean mixture, with low engine-out emissions using a properly premixed air-fuel mixture. Due to longer ignition delay and high volatility compared to diesel, gasoline-like fuels show good potential for the generation of a highly premixed charge, which is needed to reach LTC characteristics. In this scenario, gasoline Partially Premixed Combustion (PPC), characterized by the high-pressure direct injection of gasoline, showed good potential for the simultaneous reduction of pollutants and emissions in CI engines. However, previous research on gasoline CI highlight that a key factor for the optimization of both efficiency and pollutants is the proper management of Exhaust Gas Recirculation (EGR). This work presents the experimental investigation performed running a light-duty CI engine, operated with gasoline PPC, and varying the mass of recirculated gases trapped in the combustion chamber. To guarantee the stability of gasoline autoignition in all the tested conditions, a specific experimental layout has been developed to accurately quantify the amount of trapped residual gases due to the internal and external EGR. The obtained results clearly highlight the impact of EGR on the combustion process and emissions, demonstrating that optimization of charge dilution with EGR is fundamental to guarantee the optimal compromise between efficiency and emissions over the whole operating range.

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“…In previous studies by the authors [22,23], combustion phasing was represented by CA50, the crank angle at which 50% of the total energy is released. In the present study, combustion phasing is represented by the crank angle of the high temperature heat release peak to ensure a wellcontrolled and suitable combustion, even for fuels exhibiting significant low temperature heat release.…”

Section: Methodsmentioning

confidence: 99%

“…running under homogeneous charge compression ignition [18][19][20][21]. Such an approach, with the pressure-temperature diagram, was conducted by the authors [22,23]. Results showed that running HCCI experiments can help identify the conditions at which autoignition occurs in an engine for a given fuel; but for a greater understanding of the practical fuel autoignition, an octane number scale is required.…”

Section: Introductionmentioning

confidence: 99%

HCCI Octane Number Scale in a Pressure-Temperature Diagram

Masurier

Elkhazraji

Mohammed

et al. 2019

SAE Technical Paper Series

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A new approach for investigating combustion behavior of practical fuels under homogeneous charge compression ignition (HCCI) conditions was developed with the help of a cooperative fuel research (CFR) engine. The method uses a set of two pressure-temperature diagrams and two charts, each with an octane number scale based on primary reference fuels (PRF), created from experimental results by sweeping the intake temperature. The two pressure-temperature diagrams report conditions leading to the start of the low temperature combustion and the start of the main combustion, respectively. Additional two charts-required compression ratio and fraction of low temperature heat release charts-describe global combustion behavior and the importance of the low temperature combustion. Each diagram and chart, together with their respective octane number scale, allow to examine the combustion behavior of practical fuels by comparing their combustion behavior with those of the PRFs. Finally, octane numbers representing the various combustion behaviors of a practical fuel can be rated. Application of the method with two low-octane number surrogate fuels led to the following main results. The required compression ratio chart provides a quick description of the combustion behavior. The pressure-temperature diagrams indicate the ease with which a fuel ignites under low temperature combustion and main combustion regimes. An extra pressure-temperature diagram reports start and end of the negative temperature coefficient regime and highlights that this regime is independent of the fuel. Accordingly, each combustion regime is clearly defined in the pressure-temperature diagram. The fraction of low temperature heat release finally indicates how low temperature combustion vanishes. Finally, octane numbers for each practical fuel were rated from each diagram and chart. Rated octane numbers suggest that a single PRF cannot reflect the entire combustion behavior of a practical fuel; but multiple PRFs are required for HCCI combustion.

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Autoignition of Isooctane beyond RON and MON Conditions

Cited by 8 publications

References 25 publications

Injection Pattern Investigation for Gasoline Partially Premixed Combustion Analysis

Injection Pattern Investigation for Gasoline Partially Premixed Combustion Analysis

Investigation of Gasoline Partially Premixed Combustion with External Exhaust Gas Recirculation

HCCI Octane Number Scale in a Pressure-Temperature Diagram

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