DE3-3: Optimization of Piston Bowl Shape, Fuel Injection Nozzle and Fuel Injection Rate for the Reduction of NO_x Emissions in a Medium-speed Diesel Engine(DE: Diesel Engine Combustion,General Session Papers)

Author(s):  
Wook Hyeon Yoon ◽  
Byong Seok Kim ◽  
Ki Doo Kim ◽  
Yong Seok Lee ◽  
Sang Hak Ghal
2021 ◽  
Vol 3 (6) ◽  
Author(s):  
Ikhtedar Husain Rizvi ◽  
Rajesh Gupta

AbstractTightening noose on engine emission norms compelled manufacturers globally to design engines with low emission specially NOx and soot without compromising their performance. Amongst various parameters, shape of piston bowls, injection pressure and nozzle diameter are known to have significant influence over the thermal performance and emission emanating from the engine. This paper investigates the combined effect of fuel injection parameters such as pressure at which fuel is injected and the injection nozzle size along with shape of piston bowl on engine emission and performance. Numerical simulation is carried out using one cylinder naturally aspirated diesel engine using AVL FIRE commercial code. Three geometries of piston bowls with different tumble and swirl characteristics are considered while maintaining the volume of piston bowl, compression ratio, engine speed and fuel injected mass constant along with equal number of variations for injection nozzle size and pressures for this analysis. The investigation corroborates that high swirl and large turbulence kinetic energy (TKE) are crucial for better combustion. TKE and equivalence ratio also increased as the injection pressure increases during the injection period, hence, enhances combustion and reduces soot formation. Increase in nozzle diameter produces higher TKE and equivalence ratio, while CO and soot emission are found to be decreasing and NOx formation to be increasing. Further, optimization is carried out for twenty-seven cases created by combining fuel injection parameters and piston bowl geometries. The case D2H1P1 (H1 = 0.2 mm, P1 = 200 bar) found to be an optimum case because of its lowest emission level with slightly better performance.


Author(s):  
Gong Chen

The influence of inlet liquid fuel temperature on direct-injection diesel engines can be noticeable and significant. The work in this paper investigates the effects of inlet fuel temperature on fuel-injection in-cylinder combustion, and output performance and emissions of medium-speed diesel engines. An enhanced understanding and simplified modeling of the variations in the main fuel-injection parameters affected by inlet fuel temperature are developed. The study indicates that the main injection parameters affected include the injection timing at the injector end relative to the injection-pump actuation timing, the fuel-injection rate, the fuel-injection duration, and the injection spray atomization. The primary fuel temperature effects on the injection parameters are from the fuel bulk modulus of elasticity and the density with the fuel viscosity less significant as the injector-nozzle flow is usually in a turbulent region. The developed models are able to predict the changes in the injection parameters versus the inlet fuel temperature. As the inlet fuel temperature increases, the nozzle fuel-injection-start timing is predicted to be relatively retarded, the injection rate is reduced, and the needle-lift duration is prolonged from the baseline. The variation trends of the engine outputs and emissions versus fuel temperature are analyzed by considering its consequent effect on in-cylinder combustion processes. It is predicted that raising fuel temperature would result in an increase in each of CO, HC, PM, and smoke emissions, and in a decrease in NOx, and may adversely affect the fuel efficiency for a general type of diesel engine at a full-load condition. The experimental results of the outputs and emissions from testing a medium-speed four-stroke diesel engine agreed with the trends analytically predicted. The understanding and models can be applied to compression-ignition direct-injection liquid fuel engines in general.


2021 ◽  
Vol 236 ◽  
pp. 01026
Author(s):  
Dai Liu ◽  
Yingzhu Guo ◽  
Long Liu ◽  
Qian Xia ◽  
Yong Gui

Multi-injector system is potential to improve thermal efficiency and NOx emission of diesel engine at the same time. In order to optimize the combustion and emission of Marine medium speed diesel engine, the engine combustion with a multi-injector system is simulated and analyzed by CFD software Converge. In this research, two injectors are installed at the side of the cylinder head while the central injector is maintained. Various injection directions of side injectors and injection strategies of multi-injector system are simulated to optimize the fuel spray and combustion. The analysis results show that the spray angle of the side injector plays a key role for effective thermal efficiency improvement, since complex spray jet-jet interaction and spray impingement may deteriorate the combustion if the arrangement of spray angle was not set properly. Once the fuel injection direction has been optimized, the fuel ratio of the three injectors is optimized and improved the effective thermal efficiency with lower NOx emission. The results show that the two side injectors could increase the fuel injection rate into the cylinder, leading to high brake power and consequently increased the thermal efficiency by 1.26% and decreased the NOx emission by 16% for the best optimization.


1998 ◽  
Author(s):  
Terukazu Nishimura ◽  
Keiichi Satoh ◽  
Susumu Takahashi ◽  
Katsuhiko Yokota

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