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Compression-Ignition Engine Combustion
Published in Kenneth M. Bryden, Kenneth W. Ragland, Song-Charng Kong, Combustion Engineering, 2022
Kenneth M. Bryden, Kenneth W. Ragland, Song-Charng Kong
During premixed burn, a portion of fuel spray vaporizes, mixes with air, autoignites, and burns rapidly. This premixed burn phase is brief, because the mixture amount is usually small and burning is spontaneous. The main diffusion burning of the spray, which usually constitutes most of the heat release, is controlled by the mixing of fuel and air during combustion. Detailed computational modeling of diesel combustion processes is beyond the scope of this book, and instead we follow the lead of Chapter 7 and utilize pressure and volume measurements in a one-zone model to determine the heat-release rate. The formulation of the one-zone model is the same for both the gasoline engine and the diesel engine, although the conceptual image of the combustion is different. In a spark ignition engine, a turbulent-premixed flame front sweeps across the combustion chamber, whereas in a diesel engine there are various complex combustion zones in each spray plume where the mixture is not homogeneous.
Internal Combustion Engines
Published in Iqbal Husain, Electric and Hybrid Vehicles, 2021
The two types of reciprocating IC engines are the spark-ignition engine (SI) and the compression-ignition (CI) engine. The two engines are commonly known as gasoline/petrol engine and diesel engine based on the type of fuel used for combustion. The difference in the two engines is in the method of initiating the combustion and in the processes of the cycle. In a spark-ignition engine, a mixture of air and fuel is drawn in and a spark plug ignites the charge. The intake of the engine is called the charge. Electronically controlled direct fuel injection is used in modern gasoline engine vehicles, which helps to measure out the right amount of fuel in response to driver demand. In a compression-ignition engine, air alone is drawn in and compressed to such a high pressure and temperature that combustion starts spontaneously when fuel is injected. The spark-ignition engines are relatively light and lower in cost and used for lower power engines as in the conventional automobiles. The compression-ignition engines are more suitable for power conversion in the higher power range, such as in trucks, buses, locomotives, ships and in auxiliary power units. The fuel economy of compression-ignition engines is better than the spark-ignition engines justifying their use in higher power applications [1].
Combustion
Published in John B. Heywood, Eran Sher, The Two-Stroke Cycle Engine, 2017
We have been discussing the normal SI engine combustion process. An important abnormal spark-ignition engine combustion phenomenon is called knock. Knock is the result of rapid autoignition of a portion of the mixture ahead of the propagating flame.1 As the flame advances across the combustion chamber, the cylinder pressure rises, and the unburned mixture ahead of the flame (the end gas) is compressed and its temperature rises. At high enough end-gas temperatures and pressures, some parts of the end gas may undergo spontaneous ignition before the arrival of the flame front. Knock occurs when the induction time of the end-gas mixture (the time it takes for spontaneous ignition) is shorter than the time it takes for the flame front to arrive. The induction time depends on mixture composition and state and on the molecular structure of the fuel molecules. The antiknock resistance of a fuel is quantified by its octane number. The octane number of a fuel is determined by standard test procedures, in an engine designed for this purpose, that match the knock resistance of the fuel tested to that of a set of standard reference fuels. Research and motor octane numbers are obtained from different engine test conditions, the motor octane test being the more severe. Gasolines typically have research octane numbers in the range 90–100, and motor octane numbers 8–10 numbers lower; the average of the two is usually quoted as the fuel’s octane number because it scales best with in-use antiknock behavior.
Influence of ethanol-gasoline blended fuel on performance and emission characteristics of the test motorcycle engine
Published in Journal of the Air & Waste Management Association, 2022
Thanh Dinh Xuan, Dien Vu Minh, Binh Pham Hoa, Khanh Nguyen Duc, Vinh Nguyen Duy
Many other publications performed different ethanol/gasoline blends for the original gasoline engines. For instance, Farhad et al. evaluated the effect of ethanol content in the mixture on gasoline in a spark-ignition engine. The results showed that 10% ethanol (E10) blends lead to a 5% improvement in the output power and octane number increase. Furthermore, it reduces CO emissions by up to 30% (Salek et al. 2021). Bata et al. concluded that ethanol blends reduce HC and CO emissions because of the ethanol’s oxygenated characteristic and wide flammability (Rice et al. 1991). In another study, Altun et al. conducted the effect of 10% methanol (M10) and ethanol (E10) blending used for a spark-ignition engine (Iliev 2015). They showed that adding methanol and ethanol into gasoline reduces exhaust emissions. Indeed, the HC emissions were reduced respectively by 13% and 15%, and the CO emissions were decreased by 10.6% and 9.8%. However, this caused an increase in brake-specific fuel consumption (BSFC), and thus the CO2 emissions were slightly increased.
The experimental study on the performance, combustion and emission characteristics of a diesel engine using diesel – biodiesel – diethyl ether blends
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2021
Krishnamani Selvaraj, Mohanraj Thangavel
In the automotive sector, the ethanol could be used as a fuel for spark ignition engine due to higher octane number, and it is not preferable to use as a straight fuel for a diesel engine. Therefore, ethanol could be converted to diethyl ether through a dehydration process, which is an excellent fuel additive for compression ignition engines. The diethyl ether has a higher value of cetane number and calorific value with respect to the other alcohol fuels. The diethyl ether is an oxygenated fuel (21.6% by mass), and it is miscible with fuels of diesel and biodiesel. Very few experimental studies investigated the impact of diethyl ether as a combustion improver in the diesel engines.
Experimental and numerical investigation of effects of CNG and gasoline fuels on engine performance and emissions in a dual sequential spark ignition engine
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2018
Ahmet Alper Yontar, Yahya Doğu
Delpech et al. (2010) investigated effects of CNG, gasoline and concomitant injection in a turbocharged spark ignition engine. They modified compression ratio of the spark ignition engine from 9.5 to 11.5. Their tests demonstrated that engine torque for the concomitant injection mode is higher than CNG and gasoline modes because of higher volumetric and thermal efficiencies.