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Fuels
Published in Kenneth M. Bryden, Kenneth W. Ragland, Song-Charng Kong, Combustion Engineering, 2022
Kenneth M. Bryden, Kenneth W. Ragland, Song-Charng Kong
Two octane test methods are used for automobile gasoline: One provides the research octane number RON (ASTM D908), and the other provides the motor octane number MON (ASTM D357). The research method is run with 52°C inlet air at 600 rpm with a spark advance of 13 crank angle degrees (CA°) before the top dead center of the piston. The research octane number gives a higher octane rating than the motor octane number, which is run with 149°C inlet air at 900 rpm with 19–26 CA° spark advance. The average of the two octane numbers is called anti-knock index, AKI, which is the fuel rating shown on the commercial gas pump. If a fuel is more prone to autoignition than n-heptane, it will have an octane number less than 0. For example, the research octane number of n-octane is –20. If a fuel is less prone to autoignition than isooctane, it will have an octane number greater than 100. For instance, the research octane numbers of methane, ethanol, and toluene are 120, 107, and 120, respectively. Test methods to obtain octane numbers beyond the range of 0 to 100 can be referred to the ASTM methods mentioned earlier. The octane number of a fuel is dictated by its molecular structure as discussed in the previous section. Moreover, the octane rating of a fuel is only related to its autoignition tendency and does not have any implications relative to its flame speed or energy content.
Fundamentals
Published in Eberhard Lucke, Edgar Amaro Ronces, Leveraging Synergies Between Refining and Petrochemical Processes, 2020
Eberhard Lucke, Edgar Amaro Ronces
Octane rating is a measurement to quantify the detonation level (knocking) during the combustion of fuel; it’s been established with an arbitrary reference between 0 and 100 where 0 corresponds to heptane and 100 to 2,2,4-trimethylpentane (one of the most branched isomers of the octane). Octane ratings for several representative hydrocarbons are shown in Figure 2.22, in which it is visible how olefins, branched paraffins, and aromatics have higher octane ratings compared to lighter paraffins.
Engine systems
Published in Tom Denton, Automobile Mechanical and Electrical Systems, 2018
The quality of petrol (gasoline) is measured by a parameter called the octane rating, which gives an indication of the fuel’s resistance to engine ‘knock’ or uncontrolled, spontaneous combustion, which causes engine damage. Fuels with a higher octane rating burn more slowly and in a more controlled manner, and hence have a greater resistance to knock. The octane rating of the fuel determines the limit of ignition advance for a given engine speed and load condition. Therefore, it is particularly important to operate the engine on the correct fuel, to prevent damage to the engine due to knocking.
Research on the usability of various oxygenated fuel additives in a spark-ignition engine considering thermodynamic and economic analyses
Published in Biofuels, 2023
Murat Kadir Yesilyurt, Battal Dogan, Abdülvahap Cakmak
From the reviewed literature, it can be concluded that oxygenated fuels with a high octane rating have frequently been added to base gasoline to enhance the knock-resistance of the fuel and improve the engine performance and exhaust emissions. Additionally, the effects of different types of oxygenated fuels on engine behavior, combustion characteristics, and exhaust emissions have been extensively investigated and reported. However, thermodynamic analysis was not performed in these studies. The thermodynamic analysis is also required to examine the effects of oxygenated fuels on engine performance and efficiency in more detail. Exergy analysis of the engine operation reveals the work potential of energy components (i.e. fuel energy, energy loss in the cooling system, exhaust gas, radiation, friction, etc.) and irreversibilities that reduce the efficiency [29,30].
The gasoline fuel quality impact on fuel consumption, air-fuel ratio (AFR), lambda (λ) and exhaust emissions of gasoline-fueled vehicles
Published in Cogent Engineering, 2019
Shamil Ahmed Flamarz Al-Arkawazi
The gasoline octane rating is a measure of a fuel’s ability to avoid knock. Knock occurs when fuel is prematurely ignited in the engine’s cylinder, which reduces efficiency and can damage the engine. Knock is practically unknown to modern drivers. This is primarily because fuels contain an oxygenate that prevents knock by adding oxygen to the gasoline fuel. This oxygenate is commonly referred to as octane (Stolark, 2016).
Performance and emissions of gasoline blended with fusel oil that a potential using as an octane enhancer
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2019
Ahmed N. Abdalla, Omar I. Awad, Hai Tao, Thamir K. Ibrahim, Rizalman Mamat, Ali Thaeer Hammid
Depleting fossil reserves have driven engine researchers on a pursuit of fuels from renewable sources. The twin crisis of energy security and environmental safety could be addressed by this approach. This is because renewables usually are oxygenated and oxidize carcinogenic particulates from internal combustion engines. Furthermore, in the chronology of internal combustion engine development, the most sought-after and challenging objective is an improvement of engine performance. Spark ignition engines running on high research octane number fuels illustrate enhanced engine efficiency and decreased emissions (Anderson et al. 2012; Canakci et al. 2013; Thangavel et al. 2016). The thermal efficiency of SI engines can reach 44% with high octane fuels that are comparable to diesel engine efficiency (Nakata et al. 2011). The enhanced efficiency leads to reduce CO2, which assisting to alleviate greenhouse gas (Niven 2005). Octane number in gasoline indicates the ability of the fuel to resist the auto-ignition, which can make engine knockings. The ignition and compression quality of gasoline fuels are characterized via utilizing its octane rating which is covered as the motor octane number (MON) and research octane number (RON). Several engines will damage in less than 50 hours under the heavy knocking. With the high octane rating fuels can prevent the knocking in an engine and improve the engine efficiency (Gribble 1987). Around the early 1920s, manufacturers began to improve the engine performance by increasing the compression ratio. The Tetraethyl lead (TEL) was mixed with gasoline to improve the octane rating so the blended fuel can be utilized with a high compression ratio (Polls Feb 1973; Gribble 1987). By the coming years, there was quite a global consensus on the need to eradicate TEL from gasoline. Its adverse neurological impacts, particularly on human, have been definitively confirmed by several researchers around the world. By1970s, usage TEL, was prohibited in the U.S., while in Italy, it has not been sold since 2000 due to a community law, even if the newer cars use unleaded fuel from the 1990s (Shahad et al. 2008).