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1
Wang, Xinyan, Jun Ma i Hua Zhao. "Analysis of scavenge port designs and exhaust valve profiles on the in-cylinder flow and scavenging performance in a two-stroke boosted uniflow scavenged direct injection gasoline engine". International Journal of Engine Research 19, nr 5 (10.08.2017): 509–27. http://dx.doi.org/10.1177/1468087417724977.
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In this study, effects of intake scavenge port designs and exhaust valve opening profiles were studied on the scavenging process in a newly proposed two-stroke boosted uniflow scavenged direct injection gasoline engine by detailed three-dimensional engine simulations. As the most important geometric parameters, the axis inclination angle and swirl orientation angle of scavenge ports, as shown in Figure 1, were investigated and optimized for best scavenging performances at first. With the optimal axis inclination angle of 90° and swirl orientation angle of 20°, various combinations of scavenge port opening timing, exhaust valve opening duration and exhaust valve opening timing were then analysed. Four distinct scavenging periods, that is, early backflow period, backflow scavenging period, main scavenging period and post backflow period, were identified and their impacts on the in-cylinder flow motions and scavenging performances were investigated. The results show that the optimal scavenging performance can be achieved with a higher delivery ratio, charging efficiency and scavenging efficiency when the post backflow is just avoided by tuning the difference between the closing timings of scavenge ports and exhaust valves (Δ close) and the overlap between the opening profiles of scavenge ports and exhaust valves (Δ overlap) for a specific exhaust valve opening duration. A longer exhaust valve opening duration can be used to further improve the scavenging performances. In addition, the difference between the opening timings of scavenge ports and exhaust valves (Δ open) can be increased to improve scavenging efficiency. The Δ close also shows strong positive correlation with in-cylinder swirl ratio and negative correlation with tumble ratio. The results presented in this study provide the fundamental knowledge of the scavenging process in the uniflow scavenged two-stroke engine and assist the design of scavenge ports and valve strategies to optimize in-cylinder flow motion and scavenge performances in the two-stroke boosted uniflow scavenged direct injection gasoline engine with a variable valve actuation system for exhaust valves.
2
Romandoni, Nanang, Noorsakti Wahyudi, Kholis Nur Faizin i Firdho Putra Fadillah. "KADAR EMISI GAS BUANG PADA SI ENGINE 4 STROKE-LPG FUEL DENGAN VARIASI BUKAAN KATUP GAS". Jurnal Mekanova: Mekanikal, Inovasi dan Teknologi 8, nr 1 (19.04.2022): 42. http://dx.doi.org/10.35308/jmkn.v8i1.5365.
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Abstract The use of LPG fuel in spark ignition engines continues to be developed, including the use of converter kits as a conversion tool from gasoline to LPG. However, the use of converter kits is not optimal because the mixture of air and gas has not been mixed heterogeneously in the combustion chamber. Therefore, it is necessary to redesign the converter kits that speed up the mixing process between air and gas. This study aims to evaluate the use of LPG fuel in spark ignition engines with converter kits on variations in throttle valve openings on exhaust gas emissions and exhaust gas temperatures. The research method used is an experiment with variations in the throttle valve opening on the engine are 25%, 50%, 75%, and 100%. Data that will be compared on the use of gasoline and LPG fuels include carbon monoxide (CO), hydrocarbon (HC), and mean gas temperature. The results showed that the use of fuel between gasoline and LPG on exhaust gas emission levels in spark ignition engines with variations in throttle valve openings was able to reduce CO emissions by 92% on average, HC by 72%, and increase the mean average temperature by 17%. This shows that the use of converter kits at each valve opening is able to reduce levels of CO and HC exhaust emissions compared to gasoline. However, it is inversely proportional to the mean gas temperature, at each variation of the gas valve opening there is a significant increase in temperature. This is because the heating value of LPG is greater than that of gasoline.Keywords—Exhaust gas emission, spark ignition engine, throttle valve open
3
Vos, Kalen R., Gregory M. Shaver, Mrunal C. Joshi i James McCarthy. "Implementing variable valve actuation on a diesel engine at high-speed idle operation for improved aftertreatment warm-up". International Journal of Engine Research 21, nr 7 (16.10.2019): 1134–46. http://dx.doi.org/10.1177/1468087419880639.
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Aftertreatment thermal management is critical for regulating emissions in modern diesel engines. Elevated engine-out temperatures and mass flows are effective at increasing the temperature of an aftertreatment system to enable efficient emission reduction. In this effort, experiments and analysis demonstrated that increasing the idle speed, while maintaining the same idle load, enables improved aftertreatment “warm-up” performance with engine-out NOx and particulate matter levels no higher than a state-of-the-art thermal calibration at conventional idle operation (800 rpm and 1.3 bar brake mean effective pressure). Elevated idle speeds of 1000 and 1200 rpm, compared to conventional idle at 800 rpm, realized 31%–51% increase in exhaust flow and 25 °C–40 °C increase in engine-out temperature, respectively. This study also demonstrated additional engine-out temperature benefits at all three idle speeds considered (800, 1000, and 1200 rpm, without compromising the exhaust flow rates or emissions, by modulating the exhaust valve opening timing. Early exhaust valve opening realizes up to ~51% increase in exhaust flow and 50 °C increase in engine-out temperature relative to conventional idle operation by forcing the engine to work harder via an early blowdown of the exhaust gas. This early blowdown of exhaust gas also reduces the time available for particulate matter oxidization, effectively limiting the ability to elevate engine-out temperatures for the early exhaust valve opening strategy. Alternatively, late exhaust valve opening realizes up to ~51% increase in exhaust flow and 91 °C increase in engine-out temperature relative to conventional idle operation by forcing the engine to work harder to pump in-cylinder gases across a smaller exhaust valve opening. In short, this study demonstrates how increased idle speeds, and exhaust valve opening modulation, individually or combined, can be used to significantly increase the “warm-up” rate of an aftertreatment system.
4
Jiang, Da Hua, An Gui Li, Fa En Shi i Yu Jiao Zhao. "Test Analysis on Flow Field of Exhaust Hood in Commercial Kitchen". Advanced Materials Research 374-377 (październik 2011): 560–63. http://dx.doi.org/10.4028/www.scientific.net/amr.374-377.560.
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Making exhaust hood model in laboratory according to exhaust hood in commercial kitchen, steam instead of fume, and characteristics of flow field are studied in kitchen exhaust hood. The distribution of velocity and temperature at typical planes was measured at valve opening of 45 degrees when water boiling. Results show that in a certain range, air velocity of exhaust hood decreases when air from the exhaust opening distance increases, velocity reduces with x and y increasing, steam velocity reaches maximum value close to exhaust outlet of fan.
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Park, Cheolwoong, Wonah Park, Yongrae Kim, Young Choi i Byeungjun Lim. "Effect of Valve Timing and Excess Air Ratio on Torque in Hydrogen-Fueled Internal Combustion Engine for UAV". Energies 12, nr 5 (26.02.2019): 771. http://dx.doi.org/10.3390/en12050771.
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In this study, in order to convert a 2.4 L reciprocating gasoline engine into a hydrogen engine an experimental device for supplying hydrogen fuel was installed. Additionally, an injector that is capable of supplying the hydrogen fuel was installed. The basic combustion characteristics, including torque, were investigated by driving the engine with a universal engine control unit. To achieve stable combustion and maximize output, the intake and exhaust valve opening times were changed and the excess air ratio of the mixture was controlled. The changes in the torque, excess air ratio, hydrogen fuel, and intake airflow rate, were compared under low engine speed and high load (wide open throttle) operating conditions without throttling. As the intake valve opening time advanced at a certain excess air ratio, the intake air amount and torque increased. When the opening time of the exhaust valve was retarded, the intake airflow rate and torque decreased. The torque and thermal efficiency decreased when the opening time of the intake and exhaust valve advanced excessively. The change of the mixture condition’s excess air ratio did not influence the tendency of the torque variation when the exhaust valve opening time and torque increased, and when the mixture became richer and the intake valve opening time was fixed. Under a condition that was more retarded than the 332 CAD condition, the torque decreased by about 2 Nm with the 5 CAD of intake valve opening time retards. The maximum torque of 138.1 Nm was obtained at an optimized intake and the exhaust valve opening time was 327 crank angle degree (CAD) and 161 CAD, respectively, when the excess air ratio was 1.14 and the backfire was suppressed. Backfire occurred because of the temperature increase in the combustion chamber rather than because of the change in the fuel distribution under the rich mixture condition, where the other combustion control factors were constantly fixed from a three-dimensional (3D) computational fluid dynamics (CFD) code simulation.
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Joshi, Mrunal C., Dheeraj Gosala, Gregory M. Shaver, James McCarthy i Lisa Farrell. "Exhaust valve profile modulation for improved diesel engine curb idle aftertreatment thermal management". International Journal of Engine Research 22, nr 10 (9.04.2021): 3179–95. http://dx.doi.org/10.1177/1468087420969101.
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Rapid warm-up of a diesel engine aftertreatment system (ATS) is a challenge at low loads. Modulating exhaust manifold pressure (EMP) to increase engine pumping work, fuel consumption, and as a result, engine-outlet temperature, is a commonly used technique for ATS thermal management at low loads. This paper introduces exhaust valve profile modulation as a technique to increase engine-outlet temperature for ATS thermal management, without requiring modulation of exhaust manifold pressure. Experimental steady state results at 800 RPM/1.3 bar BMEP (curb idle) demonstrate that early exhaust valve opening with negative valve overlap (EEVO+NVO) can achieve engine-outlet temperature in excess of 255°C with 5.7% lower fuel consumption, 12% lower engine out NOx and 20% lower engine-out soot than the conventional thermal management strategy. Late exhaust valve opening with internal EGR via reinduction (LEVO+Reinduction) resulted in engine-outlet temperature in excess of 280°C, while meeting emission constraints at no fuel consumption penalty. This work also demonstrates that LEVO in conjunction with modulation of exhaust manifold pressure results in engine-outlet temperature in excess of 340°C while satisfying desired emission constraints. Aggressive use of LEVO can result in engine-outlet temperatures of 460°C, capable of active regeneration of DPF at curb idle, without the significant increase in engine-out soot emissions seen in previously studied strategies.
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Luo, Qing Guo, Hong Bin Liu i Qiang Ma. "Study on Optimization of the Diesel Engine Controlling Parameters Based on Genetic Algorithm". Applied Mechanics and Materials 253-255 (grudzień 2012): 2125–29. http://dx.doi.org/10.4028/www.scientific.net/amm.253-255.2125.
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The diesel engine simulation model build by the GT-POWER software was tested and verified. The advance angle of injection, the opening angle of intake valve and the opening angle of exhaust valve was calculated to get the virtual test sample of diesel engine running under the rated condition. The optimization model was built based on the genetic algorithm, and three parameters were optimized aimed at the economic efficiency under the constraint of the maximum pressure in cylinder and the exhaust temperature; the error between the optimization and the simulation result was below 3%.
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Poljak, Igor, Ivica Glavan i Toma Ribičić. "Hydraulic System of Fuel Oil Supply to the Electronically Controlled Main Engine". Journal of Maritime & Transportation Science 60, nr 1 (lipiec 2021): 9–19. http://dx.doi.org/10.18048/2021.60.01.
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Hydraulic system of the fuel oil supply to the electronically controlled main engine resolve the problem of the optimized control of the engine which act beneficially to the specific fuel oil consumption and a reduction of the NOx emission. The assumed numerical example is giving insight to the power consumption for the hydraulic control of the fuel oil injection and exhaust valve operation for the two stroke marine engine. The calculated power is higher for the fuel oil pressure booster operation compared to the exhaust valve actuator for about 88%, which is resulted due to the higher operating pressure of the fuel injection to the cylinder, versus lower operating pressure required for the opening of the exhaust valve.
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Zhang, Defu, Zhenyu Shen, Nan Xu, Tingting Zhu, Lei Chang i Hui Song. "Development of a Zero-Dimensional Model for a Low-Speed Two-Stroke Marine Diesel Engine with Exhaust Gas Bypass and Performance Evaluation". Processes 11, nr 3 (19.03.2023): 936. http://dx.doi.org/10.3390/pr11030936.
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Most large commercial vessels are propelled by low-speed two-stroke diesel engines due to their fuel economy and reliability. With increasing international concern about emissions and the rise in oil prices, improvements in engine efficiency are urgently needed. In the present work, a zero-dimensional model for a low-speed two-stroke diesel engine is developed that considers the exhaust gas bypass and geometry structures for the gas exchange model. The model was applied to a low-speed two-stroke 7G80 ME-C9 marine diesel engine and validated with engine shop test data, which consisted of the main engine performance parameters and cylinder pressure diagrams at different loads. The simulation results were in good agreement with the experimental data. Thus, the model has the ability to predict engine performance with good accuracy. After model validation, the variations in compression ratio, fuel injection timing, exhaust gas bypass valve opening portion, exhaust valve opening timing, and exhaust valve closing timing effects on engine performance were tested. Finally, the influence level of different parameters on engine performance was summarized, which can be used as a reference to determine the reasons for high fuel consumption in some cases. The developed engine performance model is considerable in digital twins for performance simulation, health management, and optimization.
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Guan, Wei, Vinícius B. Pedrozo, Hua Zhao, Zhibo Ban i Tiejian Lin. "Variable valve actuation–based combustion control strategies for efficiency improvement and emissions control in a heavy-duty diesel engine". International Journal of Engine Research 21, nr 4 (26.04.2019): 578–91. http://dx.doi.org/10.1177/1468087419846031.
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High nitrogen oxide levels of the conventional diesel engine combustion often requires the introduction of exhaust gas recirculation at high engine loads. This can adversely affect the smoke emissions and fuel conversion efficiency associated with a reduction of the in-cylinder air-fuel ratio (lambda). In addition, low exhaust gas temperatures at low engine loads reduce the effectiveness of aftertreatment systems necessary to meet stringent emissions regulations. These are some of the main issues encountered by current heady-duty diesel engines. In this work, variable valve actuation–based advanced combustion control strategies have been researched as means of improving upon the engine exhaust temperature, emissions, and efficiency. Experimental analysis was carried out on a single-cylinder heady-duty diesel engine equipped with a high-pressure common-rail fuel injection system, a high-pressure loop cooled exhaust gas recirculation, and a variable valve actuation system. The variable valve actuation system enables a late intake valve closing and a second intake valve opening during the exhaust stroke. The results showed that Miller cycle was an effective technology for exhaust temperature management of low engine load operations, increasing the exhaust gas temperature by 40 °C and 75 °C when running engine at 2.2 and 6 bar net indicated mean effective pressure, respectively. However, Miller cycle adversely effected carbon monoxide and unburned hydrocarbon emissions at a light load of 2.2 bar indicated mean effective pressure. This could be overcome when combining Miller cycle with a second intake valve opening strategy due to the formation of a relatively hotter in-cylinder charge induced by the presence of internal exhaust gas recirculation. This strategy also led to a significant reduction in soot emissions by 82% when compared with the baseline engine operation. Alternatively, the use of external exhaust gas recirculation and post injection on a Miller cycle operation decreased high nitrogen oxide emissions by 67% at a part load of 6 bar indicated mean effective pressure. This contributed to a reduction of 2.2% in the total fluid consumption, which takes into account the urea consumption in aftertreatment system. At a high engine load of 17 bar indicated mean effective pressure, a highly boosted Miller cycle strategy with exhaust gas recirculation increased the fuel conversion efficiency by 1.5% while reducing the total fluid consumption by 5.4%. The overall results demonstrated that advanced variable valve actuation–based combustion control strategies can control the exhaust gas temperature and engine-out emissions at low engine loads as well as improve upon the fuel conversion efficiency and total fluid consumption at high engine loads, potentially reducing the engine operational costs.
11
Li, Yuelin, Zihan Zhang, Zhiqiang Liu, Peng Tong, Dezhi Yang i Wulong Zhang. "Effect of Negative Valve Overlap on Combustion and Emissions of CNG-Fueled HCCI Engine with Hydrogen Addition". International Journal of Aerospace Engineering 2021 (4.02.2021): 1–14. http://dx.doi.org/10.1155/2021/8898796.
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In order to study the effect of negative valve overlap on combustion and emission characteristics of a homogeneous charge compression ignition engine fueled with natural gas and hydrogen, the test and the simulation were conducted using an engine cycle model coupling the chemical kinetic reaction mechanism under different valve timing conditions. Results show that the internal EGR formed by using negative valve overlap could heat the inlet mixtures and improve the spontaneous ignition characteristic of the engine. The residual exhaust gas could slow down the heat release rate, decrease the pressure rise rate and the maximum combustion temperature, and reduce the NOx emission simultaneously. Among the three NVO schemes, the strategy of changing the intake valve opening timing individually can create the least power loss, and the symmetric NVO strategy which changes both the exhaust valve closing timing and the intake valve opening timing simultaneously can achieve the best heating effect of inlet mixtures and the satisfactory decrease of combustion temperature, as well as the largest reduction of NOx emission.
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Gosala, Dheeraj B., Aswin K. Ramesh, Cody M. Allen, Mrunal C. Joshi, Alexander H. Taylor, Matthew Van Voorhis, Gregory M. Shaver i in. "Diesel engine aftertreatment warm-up through early exhaust valve opening and internal exhaust gas recirculation during idle operation". International Journal of Engine Research 19, nr 7 (20.09.2017): 758–73. http://dx.doi.org/10.1177/1468087417730240.
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A large fraction of diesel engine tailpipe NOx emissions are emitted before the aftertreatment components reach effective operating temperatures. As a result, it is essential to develop technologies to accelerate initial aftertreatment system warm-up. This study investigates the use of early exhaust valve opening (EEVO) and its combination with negative valve overlap to achieve internal exhaust gas recirculation (iEGR), for aftertreatment thermal management, both at steady state loaded idle operation and over a heavy-duty federal test procedure (HD-FTP) drive cycle. The results demonstrate that implementing EEVO with iEGR during steady state loaded idle conditions enables engine outlet temperatures above 400 °C, and when implemented over the HD-FTP, is expected to result in a 7.9% reduction in tailpipe-out NOx.
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Li, Jingxiang, i Shengdun Zhao. "Optimization of valve opening process for the suppression of impulse exhaust noise". Journal of Sound and Vibration 389 (luty 2017): 24–40. http://dx.doi.org/10.1016/j.jsv.2016.11.015.
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ASTAWA, KETUT. "PENCAPAIAN PERFORMA PADA KATUP VARIABEL TIMING FIXED TIMING UNTUK MESIN YANG OPTIMAL". Jurnal Teknik Industri 11, nr 1 (18.02.2012): 68. http://dx.doi.org/10.22219/jtiumm.vol11.no1.68-74.
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Problems will be discussed in this research is how differences in exhaust emissions generatedby engine with variable valve timing and valve timing on a fixed volume of motor vehiclecylinder 1300 cc. Variable valve timing technology, which is set when opening and closingthe intake valve (intake valve) electronic fuel according to engine conditions. This will makemixing air and fuel that enters into an efficient machine that will produce great power, fueleconomy and low emissions. Research emissions (CO, CO2, HC, O2) was performedwith dynamictesting, where the vehicle in a state of the load lifted and given transmission. Unlikethe testing generally performed with a static test, in which the vehicle is at rest and without aload. This test is performed to determine how the condition of exhaust gases when the vehicledynamic (analogous to the vehicle running). In general, machines with variable valve timingto produce better emissions than engines with fixed valve timing. The higher the spin machineand load transmission system will result in CO and HC emissions are decreased and O2 andCO2 increased. Engine with variable valve timing control the suction valve opening times toachieve optimum engine performance at various driving conditions. And set out the engineoutput as needed.
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Weclaś, M., A. Melling i F. Durst. "Characteristics of scavenging flow in transfer ports of a motored two-stroke engine". Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 211, nr 4 (1.04.1997): 301–17. http://dx.doi.org/10.1243/0954407971526452.
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A real two-stroke engine [specifically an Orbital Combustion Process X (OCP-X) engine] was optically modified for application of laser Doppler anemometry (LDA) and flow visualization. Two velocity components were measured in two transfer ports of the motored engine. Spatial and temporal distributions of velocity indicated that the scavenge flow was very complex, highly non-uniform across the transfer ports, and strongly time dependent with respect to the port opening and closing periods. Mean velocities averaged over these two periods characterize the scavenge flow in the transfer ports but do not represent the velocity peaks at the port opening and closing, respectively. Effects of the exhaust valve in the exhaust port and of depression applied to the exhaust port on the temporal distribution of scavenge flow in transfer ports were significant only for a high enough pressure difference between the crankcase and the exhaust.
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Basaran, Hasan Ustun. "Enhanced Exhaust after-Treatment Warmup in a Heavy-Duty Diesel Engine System via Miller Cycle and Delayed Exhaust Valve Opening". Energies 16, nr 12 (6.06.2023): 4542. http://dx.doi.org/10.3390/en16124542.
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The exhaust after-treatment (EAT) threshold temperature is a significant concern for highway vehicles to meet the strict emission norms. Particularly at cold engine start and low loads, EAT needs to be improved above 250 °C to reduce the tailpipe emission rates. Conventional strategies such as electrical heating, exhaust throttling, or late fuel injection mostly need a high fuel penalty for fast EAT warmup. The objective of this work is to demonstrate using a numerical model that a combination of the Miller cycle and delayed exhaust valve opening (DEVO) can improve the tradeoff between EAT warmup and fuel consumption penalty. A relatively low-load working condition (1200 RPM speed and 2.5 bar BMEP) is maintained in the diesel engine model. The Miller cycle via retarded intake valve closure (RIVC) is noticeably effective in increasing exhaust temperature (as high as 55 °C). However, it also dramatically reduces the exhaust flow rate (over 30%) and, thus, is ineffective for rapid EAT warmup. DEVO has the potential to enhance EAT warmup via increased exhaust temperature and increased exhaust flow rate. However, it considerably decreases the brake thermal efficiency (BTE)—by up to 5%—due to high pumping loss in the system. The RIVC + DEVO combined technique can elevate the exhaust temperature above 250 °C with improved fuel consumption—up to 10%—compared to DEVO alone as it requires a relatively lower rise in pumping loss. The combined method is also superior to RIVC alone. Unlike RIVC alone, the RIVC + DEVO combined mode does not need the extreme use of RIVC to increase engine-out temperature above 250 °C and, thus, provides relatively higher heat transfer rates (up to 103%) to the EAT system through a higher exhaust flow rate. The RIVC + DEVO combined method can be technically more difficult to implement compared to other methods. However, it has the potential to maintain accelerated EAT warmup with improved BTE and, thus, can keep emission rates at low levels during cold start and low loads.
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Morel, T., R. Keribar, M. Sawlivala i N. Hakim. "Application of Several Variable-Valve-Timing Concepts to an LHR Engine". Journal of Engineering for Gas Turbines and Power 109, nr 4 (1.10.1987): 402–9. http://dx.doi.org/10.1115/1.3240055.
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An analytical study was made of advantages provided by electronically controlled hydraulically activated valves when applied to a low heat rejection engine with and without exhaust heat recovery devices. The valves, which could be designed to operate with variable timings and variable rates of opening and closing, would allow the use of certain sophisticated valve strategies not possible with conventional systems. Three individual investigations were carried out. The first concerned the optimization of the timing and rate of valve opening at several speeds and loads, to obtain maximum volumetric efficiency and lowest BSFC. A second investigated early intake valve closing (IVC before BDC), coupled with increased boost, a concept that had been suggested previously in the literature. The present results showed much lower benefits than those predicted by the earlier study. The final study addressed the use of an organic Rankine cycle bottomer (ORCB) to extract energy from the exhaust stream and directing the ORCB output power to the engine air compressor shaft rather than to the engine output shaft. At rated engine conditions, when not employing a power turbine, this concept was found to produce higher BSFC compared to the more standard configuration where the ORBC was directly coupled to the engine shaft. When a power turbine was used between the engine and the ORCB, nearly the same BSFC was achieved with the two configurations.
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Serrano, José R., Francisco J. Arnau, Jaime Martín i Ángel Auñón. "Development of a Variable Valve Actuation Control to Improve Diesel Oxidation Catalyst Efficiency and Emissions in a Light Duty Diesel Engine". Energies 13, nr 17 (3.09.2020): 4561. http://dx.doi.org/10.3390/en13174561.
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Growing interest has arisen to adopt Variable Valve Timing (VVT) technology for automotive engines due to the need to fulfill the pollutant emission regulations. Several VVT strategies, such as the exhaust re-opening and the late exhaust closing, can be used to achieve an increment in the after-treatment upstream temperature by increasing the residual gas amount. In this study, a one-dimensional gas dynamics engine model has been used to simulate several VVT strategies and develop a control system to actuate over the valves timing in order to increase diesel oxidation catalyst efficiency and reduce the exhaust pollutant emissions. A transient operating conditions comparison, taking the Worldwide Harmonized Light-Duty Vehicles Test Cycle (WLTC) as a reference, has been done by analyzing fuel economy, HC and CO pollutant emissions levels. The results conclude that the combination of an early exhaust and a late intake valve events leads to a 20% reduction in CO emissions with a fuel penalty of 6% over the low speed stage of the WLTC, during the warm-up of the oxidation catalyst. The same set-up is able to reduce HC emissions down to 16% and NOx emission by 13%.
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Shu, Yue, Jun Xiao, Zhilong Liu i Fengyu Li. "Research on transient dynamic behavior and stress of reciprocating compressor valve under air volume regulation". Journal of Physics: Conference Series 2254, nr 1 (1.04.2022): 012050. http://dx.doi.org/10.1088/1742-6596/2254/1/012050.
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Abstract By establishing the motion equation of the air valve under the condition of air volume adjustment, the motion law of the air valve in the process of expansion, compression, suction and exhaust of the reciprocating compressor under different loads is calculated, and the reciprocating compressor with stepless air volume adjustment is used. The compressor unit verifies the calculation results. The maximum stress of the valve plate under different loads is analyzed, and the results show that in the ideal state where the fork pressure disappears instantaneously, the adjustment method of the partial stroke pressure opening suction valve has a greater influence on the stress concentration of the valve plate than the normal condition; in the partial stroke pressure opening suction valve adjustment method, the free retraction speed and stress of the valve plate will increase as the compressor load decreases.
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Shu, Yue, Jun Xiao, Zhilong Liu i Fengyu Li. "Research on transient dynamic behavior and stress of reciprocating compressor valve under air volume regulation". Journal of Physics: Conference Series 2254, nr 1 (1.04.2022): 012050. http://dx.doi.org/10.1088/1742-6596/2254/1/012050.
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Abstract By establishing the motion equation of the air valve under the condition of air volume adjustment, the motion law of the air valve in the process of expansion, compression, suction and exhaust of the reciprocating compressor under different loads is calculated, and the reciprocating compressor with stepless air volume adjustment is used. The compressor unit verifies the calculation results. The maximum stress of the valve plate under different loads is analyzed, and the results show that in the ideal state where the fork pressure disappears instantaneously, the adjustment method of the partial stroke pressure opening suction valve has a greater influence on the stress concentration of the valve plate than the normal condition; in the partial stroke pressure opening suction valve adjustment method, the free retraction speed and stress of the valve plate will increase as the compressor load decreases.
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Mahrous, A.-F. M., M. L. Wyszynski, T. Wilson i H.-M. Xu. "Computational fluid dynamics simulation of in-cylinder flows in a motored homogeneous charge compression ignition engine cylinder with variable negative valve overlapping". Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 221, nr 10 (1.10.2007): 1295–304. http://dx.doi.org/10.1243/09544070jauto355.
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In-cylinder air motion is one of the most important factors that control the degree of mixture preparation and thus is fundamental to improvements in the combustion process and overall engine performance. The major aim of this paper is to elucidate, through a predictive study, the main features of in-cylinder flow fields in a motored homogeneous charge compression ignition (HCCI) engine cylinder with variable negative valve overlapping (NVO). A commercial finite-volume computational fluid dynamics (CFD) package was used in the programme of simulation. The computational model was validated through a qualitative comparison between CFD results and the available experimental data. Thus one of the main developments presented in this study is the investigation of the intake process of the HCCI engine with various valve strategies, and it is perhaps the first time (to the current authors' best knowledge) that a direct comparison has been made of the results obtained in the same HCCI NVO motored engine using modelling and experimental approaches. The comparison illustrated a fair agreement between both sets of results, with some differences. A parametric predictive study of the effects of variable valve timings on the in-cylinder air motion has then been carried out. Three different sets of valve timings have been applied to the intake and exhaust valves to generate NVO of 70, 90, and 110 degrees of crank angle (°CA). The NVO was controlled by adjusting the times of exhaust valves closing (EVC) and intake valves opening (IVO) while keeping the times of exhaust valves opening (EVO) and intake valves closing (IVC) unchanged. The predicted results show a noticeable modification of the strength and the global direction of the in-cylinder charge motion as a result of increasing the magnitude of NVO. Modifications of in-cylinder swirl and tumble motions obtained by applying higher degrees of NVO are expected to have a considerable effect on the air-fuel mixture preparation process as well as the actual in-cylinder conditions at the end of the compression stroke.
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Roberts, Leighton, Mark Magee, Gregory Shaver, Akash Garg, James McCarthy, Edward Koeberlein, Eric Holloway, Raymond Shute, David Koeberlein i Douglas Nielsen. "Modeling the impact of early exhaust valve opening on exhaust aftertreatment thermal management and efficiency for compression ignition engines". International Journal of Engine Research 16, nr 6 (6.10.2014): 773–94. http://dx.doi.org/10.1177/1468087414551616.
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Caton, P. A., A. J. Simon, J. C. Gerdes i C. F. Edwards. "Residual-effected homogeneous charge compression ignition at a low compression ratio using exhaust reinduction". International Journal of Engine Research 4, nr 3 (1.06.2003): 163–77. http://dx.doi.org/10.1243/146808703322223306.
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Studies have been conducted to assess the performance of homogeneous charge compression ignition (HCCI) combustion initiated by exhaust reinduction from the previous engine cycle. Reinduction is achieved using a fully flexible electrohydraulic variable-valve actuation system. In this way, HCCI is implemented at low compression ratio without throttling the intake or exhaust, and without preheating the intake charge. By using late exhaust valve closing and late intake valve opening strategies, steady HCCI combustion was achieved over a range of engine conditions. By varying the timing of both valve events, control can be exerted over both work output (load) and combustion phasing. In comparison with throttled spark ignition (SI) operation on the same engine, HCCI achieved 25–55 per cent of the peak SI indicated work, and did so at uniformly higher thermal efficiency. This was accompanied by a two order of magnitude reduction in NO emissions. In fact, single-digit (ppm) NO emissions were realized under many load conditions. In contrast, hydrocarbon emissions proved to be significantly higher in HCCI combustion under almost all conditions. Varying the equivalence ratio showed a wider equivalence ratio tolerance at low loads for HCCI.
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Teodorescu, M., V. Votsios i H. Rahnejat. "Multiphysics analysis for the determination of valvetrain characteristics". Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 219, nr 9 (1.09.2005): 1109–17. http://dx.doi.org/10.1243/095440705x34801.
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The ideal function of a valvetrain system is to synchronize the opening and closing of the inlet and exhaust valves with the required thermodynamics of the combustion process. As such, ideally a kinematic-type mechanism is desired. However, the timing requirements in the action of each valve and between any inlet-exhaust pair necessitate the use of contacting pairs of suitable profiles. The very existence of contact renders the problem one of complex non-linear dynamics, which is further exacerbated by the translational imbalance of the reciprocating compliant elements such as the valve itself. The interplay between these various forms of dynamics, inertial, structural, and impact/contact, make the problem quite complex to analyse. As a result, some of the most important problems with valvetrains are only surmised at, rather than fundamentally understood. The multiphysics modelling approach proposed in this paper renders a better understanding, as well as conforming to experimental observations.
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Shihan, Al-Jumaili Abdulsatar KH, i V. V. Serebryakov. "Analysis of the effectiveness and the possibility of creating an auxiliary braking system for an electronically controlled vehicle of the utility patent No. 153 247". Traktory i sel'hozmashiny 1, nr 1 (2021): 64–72. http://dx.doi.org/10.31992/0321-4443-2021-1-64-72.
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The paper notes that electronic control of work processes in vehicle units and systems is one of the most effective and modern ways to improve their operational parameters. The means of elec-tronics make it possible to increase the average speed of vehicles, reduce fuel consumption, improve controllability, stability, passability and smoothness of driving, improve braking performance and safety, and facilitate driving. All modern vehicles electronic systems are digital, data transfer rate is up to 1 megabit per se-cond. This allows each sensor to be used for several systems. Dimensions of sensors are gradually decreasing; their speed, reliability, and accuracy are increasing. One perspective way to improve vehicles is the use of an internal combustion engine with electronic control of its braking torque as an auxiliary braking system. The analysis of the utility patent No. 153 247 “Auxiliary braking system of vehicle with elec-tronic control” is considered. Its analysis using the valve timing diagrams is made. The errors made in the description of the patent were revealed. The description of the intake and exhaust strokes does not take into account the increase in the cylinder volume by the manifold volume due to the opening of the respective valves and the fact that the pressure in the exhaust tract is limited by the preloading force of the engine exhaust brake springs. The electromagnetic valve must have operation speed of an order of magnitude greater than standard valves and the same capacity; its springs must have a large pre-pressure so that it does not open under the pressure in the receiver of the regular brake system. For fast pressure release, the electromagnetic valve must open a large flow cross-section as quickly as possible, overcoming the force of the high pressure acting on its disc in the cylinder (7.5 MPa) plus the force of pre-pressure of the valve springs. The formulas for determination of the valve throughput capacity are given. Their analysis showed that to ensure a given capacity of the valve by reducing its opening time it is necessary to proportionally increase the height of the rise of electro-magnetic valve or the average diameter that is not always possible. The carried out in the paper analysis showed that the efficiency of the proposed system is lower than the declared one, and its creation is impossible because there is no electromagnetic air valve satisfying the requirements for it in this design.
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Wang, Cun Xian, Shuo Shuo Wei i Fan Zhang. "Development of Automatic Detection System for EGR Valve Position Sensor". Applied Mechanics and Materials 799-800 (październik 2015): 1166–71. http://dx.doi.org/10.4028/www.scientific.net/amm.799-800.1166.
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As an effective way for controlling emission of nitrogen oxide, EGR (Exhaust Gas Recirculation) has been widely used in automobiles. EVP (EGR valve position sensor) is a key component in EGR and functions as obtaining the accurate EGR valve opening position for governing the recirculation volume of exhaust gas. Its overall quality and working accuracy affect the performance of EGR directly and must be detected stringently before delivered from the factory. To solve the problems of labor intensity, low detecting efficiency, big deviation results with traditional EVP manual detection equipment in an automotive electronics company, an automatic detection system for EVP is developed based on PLC and industrial microcomputer. The working principle and structure of the system and design of EVP detection fixture are present, and hardware and software of its control system are developed in the paper. Three function modules, that are manual operation, automatic operation and data statistical analysis, are described in more detail. The practical application shows that the automatic detection system for EVP can achieve detection process flexibility, increase detection efficiency and accuracy greatly and solve the problems with traditional method effectively.
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Banis, Kārlis. "The Effect of separated Expansion Chamber Parameters on Exhaust Pressure Oscillations in Single Cylinder Motorcycle Engine". Rural Sustainability Research 43, nr 338 (1.08.2020): 42–51. http://dx.doi.org/10.2478/plua-2020-0006.
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AbstractThis paper investigates the effect of separated exhaust expansion chamber parameters on pressure oscillations in spark-ignited internal combustion (IC) gasoline engines. It is known that exhaust expansion chambers are becoming increasingly more popular among both – original equipment (OE) and aftermarket equipment (AE) exhaust system manufacturers for performance-oriented motorcycles equipped with mainly single cylinder engines, but the companies are reluctant to reveal any detailed principles of operation of the mentioned expansion chambers. The subject of this research is the type of expansion chamber (separate) as used on performance-oriented motorcycles, particularly its’ effect on exhaust pressure pulsations as different chamber volumes, locations and passage sizes are tested. Time-dependent computational fluid dynamics (CFD) analysis was carried out in Solidworks Flow Simulation environment on a simplified exhaust header pipe model imitating engine operation at full load and steady speed. Honda CRF450R motorcycle engine was used as the example and fully defined using a 1D engine performance calculator software to determine the combustion chamber pressure and exhaust valve lift at any given crankshaft position. Volume flow rate of exhaust gasses at the header pipe inlet was calculated based on engine parameters and operating speed. The average pressure values with respect to physical time were measured and graphed across the header pipe inlet cross-section. Eight different header pipe and exhaust expansion chamber combinations were modelled, tested, and results compared at low, medium and high engine speeds. It was found that the presence of exhaust expansion chamber tends to dampen the amplitude and decrease the frequency of pressure oscillations generated at the opening of the exhaust valve(s). Observations show that the addition of an expansion chamber as per design of performance-oriented motorcycles helps to decrease the negative effect of engine tuning while also dampening the positive effect.
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Kumar, Praveen, i Yu Zhang. "Variable Valve Strategy Evaluation for Low-Load Operation in a Heavy-Duty Gasoline Compression Ignition Engine". Energies 15, nr 6 (10.03.2022): 2017. http://dx.doi.org/10.3390/en15062017.
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By harnessing gasoline’s low reactivity for partially premixed combustion promotion, gasoline compression ignition (GCI) combustion shows the potential to produce markedly improved NOx-soot trade-off with high fuel efficiency compared to conventional diesel combustion. However, at low-load conditions, gasoline’s low reactivity poses challenges to attaining robust combustion with low unburned hydrocarbons (UHC) and carbon monoxide (CO) emissions. Increasing the in-cylinder charge temperature by using variable valve actuation (VVA) can be an effective means to address these challenges. In this numerical investigation, VVA strategies, including (1) early exhaust valve opening (EEVO), (2) positive valve overlap (PVO), and (3) exhaust rebreathe (ExReb), were investigated at 1375 RPM and 2 bar brake mean effective pressure in a heavy-duty GCI engine using a market-based gasoline with a research octane number (RON) of 93. The total residual gas level was kept over 50% to achieve an engine-out NOx target of below 1.5 g/kWh. For a complete engine system analysis, one-dimensional (1-D) system-level modeling and three-dimensional (3-D) computational fluid dynamics (CFD) analysis were close-coupled in this study. Performance of the VVA strategies was compared in terms of in-cylinder charge and exhaust gas temperatures increase versus brake-specific fuel consumption (BSFC). The EEVO strategy demonstrated in-cylinder charge and exhaust temperature increase up to 130 and 180 K, respectively. For similar in-cylinder charge temperature gains, the ExReb strategy demonstrated 11% to 18% lower BSFC compared to the EEVO strategy. This benefit primarily originated from a more efficient gas-exchange process. The PVO strategy, due to the valve–piston contact constraint, required excessive exhaust back-pressure valve (BPV) throttling for hot residuals trapping, thereby incurring higher BSFC compared to ExReb. In addition, the ExReb strategy demonstrated the highest potential for exhaust temperature increase (up to 673 K) among the three strategies. This was achieved by ExReb’s maximum air-fuel ratio reduction from high internal residuals mass and BPV throttling. Finally, the ExReb profile was optimized in terms of the peak lift, the duration, and the location for maximizing the fuel-efficiency potential of the strategy.
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Bencherif, Mohamed, Tewfik Leftas i Nasreddine Larbes. "Numerical analysis of injection parameters influence on experimental diesel engine performances and emissions using [CO] and [NOx] correlated by maximum in-cylinder pressure". Thermal Science, nr 00 (2023): 17. http://dx.doi.org/10.2298/tsci220120017b.
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The present work deals with a numerical investigation on an experimental single cylinder direct injection diesel engine. Calculations are carried out with kiva3v2 code using multidimensional detailed chemistry. The study was carried out on predicted CO, and NOx emission levels by the engine cylinder before exhaust valve opening. Correlations proposed for predicted NO, CO and NOx levels function of fuel, O2, N2 concentrations and the maximum in-cylinder pressure rather than temperature. Predicted values of averaged pressures, O2, CO and CO2 levels in the exhaust manifold were validated by the measured ones for a set of five loads at 1500 rpm. CO, NO and NOx concentrations at the exhaust obtained by calculations lies perfectly with measured values. Otherwise, numerical simulations lead us to analyze injection timing, duration and fuel amount injected effect on the engine performances, ignition delay, combustion duration as well as CO and NOx emission levels.
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Shishkov, Vladimir Aleksandrovich. "METHOD OF SUPPLYING FUEL TO AN INTERNAL COMBUSTION ENGINE". Journal of Dynamics and Vibroacoustics 7, nr 4 (20.12.2021): 20–29. http://dx.doi.org/10.18287/2409-4579-2021-7-4-20-29.
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Purpose of work: the purpose of the work is to improve the accuracy of fuel dosing during cyclic supply and reduce toxic emissions of exhaust gases into the atmosphere of an internal combustion engine. The method relates to power and transport engineering and is intended for ground-based power plants and vehicles. The method consists in cyclic fuel supply through the injectors, while measuring the fuel pressure at its inlet during the calibration work of the internal combustion engine electronic control system, by measuring the fuel pressure in front of each injector, the integral value of its drop during the open state of the valve of each injector is determined, depending on crankshaft speed and load on the internal combustion engine and record it in the non-volatile memory of the electronic control unit of the internal combustion engine, and during its operation, before opening the valve of each injector, the fuel pressure at its inlet is increased by the corresponding integral value of its drop during the valve open period injector recorded in the non-volatile memory of the electronic control unit. Due to the correction of the fuel pressure in front of the injector and the correction of the cyclic fuel supply of each individual injector, the accuracy of its dosing is increased, which reduces the toxicity of the exhaust gases of the internal combustion engine.
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Uzkan, T. "An Analysis of the Engine Blowdown Process Using Multidimensional Computations". Journal of Engineering for Gas Turbines and Power 109, nr 4 (1.10.1987): 459–64. http://dx.doi.org/10.1115/1.3240064.
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The details of the blowdown period were studied for the EMD-710 diesel engine by using a multidimensional computational code for in-cylinder flows. Computed results are presented describing both global and detailed features of the flow field during the blowdown period. Global features include variations of cylinder pressure, mass, angular momentum, turbulence kinetic energy, and the exhaust mass. A parametric analysis has shown that the percent pressure drop and the percent mass exhausted are almost invariable with the initial cylinder pressure or mass. Details of the mass convection process within the cylinder are investigated through development of the line separating the downward and upward flowing gas regions. The location and speed of propagation of this separation line are also found to be independent of initial cylinder pressure and mass. The results show that the speed of the separation line is about twice the piston speed for an initial period of 15 deg crank angle. Then it starts to decrease and becomes equal to the piston speed at about 26 deg after the exhaust valve opening. Beyond this time the separation line is slower than the piston speed.
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Frolov, Sergey M., Konstantin A. Avdeev, Vladislav S. Ivanov, Pavel A. Vlasov, Fedor S. Frolov, Ilya V. Semenov i Marina S. Belotserkovskaya. "Evolution of the Soot-Particle Size Distribution Function in the Cylinder and Exhaust System of Piston Engines: Simulation". Atmosphere 14, nr 1 (22.12.2022): 13. http://dx.doi.org/10.3390/atmos14010013.
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A computational tool for simulating the temporal evolution of the soot-particle size distribution function (SDF) in the internal combustion engine (ICE) and in the attached exhaust pipe is developed and tested against available experimental data on the soot-particle SDF at the outlet of the exhaust system. Firstly, a database of soot particle properties (particle mean diameter, dispersion, total particle number density vs. time for different fuels, fuel-to-air equivalence ratios, temperatures, pressures, and exhaust gas recirculation) is developed based on the thoroughly validated detailed model of soot formation under ICE conditions. The database is organized in the form of look-up tables. Secondly, the soot-particle SDF in the database is approximated using the log-normal SDF, which is directly used in the multidimensional calculations of the ICE operation process. Thirdly, the coagulation model of soot particles is developed, which includes three coagulation mechanisms: Brownian, turbulent–kinetic, and turbulent–diffusion. This model is applied for simulating the evolution of the soot-particle SDF in the exhaust pipe after opening the exhaust valve. Calculations show that the coagulation process of soot particles in the exhaust pipe has a significant effect on the mean size of particles at the outlet of the exhaust system (the mean particle diameter can increase by almost an order of magnitude), and the dominant mechanism of particle coagulation in the exhaust system of a diesel engine is the Brownian mechanism. The objective, approach, and obtained results are the novel features of the study.
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Meskhi, Besarion, Boris Golev, Victor Efros, Dmitriy Rudoy, Anastasiya Olshevskaya, Viktor Zhurba i Yevgeniy Chayka. "Influence of parameters and location of the tumble inlet porton air charging in the diesel cylinder". E3S Web of Conferences 135 (2019): 01083. http://dx.doi.org/10.1051/e3sconf/201913501083.
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The calculation of the actual working cycle processes allows to determine with satisfactory accuracy the value of the main parameters of the newly developed engine for any given conditions of its operation, to assess the impact of individual factors on the processes and the performance of the cycle as a whole. Thus establish character of change of pressure and temperature in each process, define the sizes of the engine, and also solve questions of increase of its reliability taking into account the received settlement thermal and dynamic loadings. Pre-intake begins at the time of opening the inlet and ends at the time of arrival of the piston in the TDC. The mixture or air does not enter the cylinder during preheating, as the volume of the cylinder decreases. However, the pre-opening of the intake valve allows you to create a sufficient cross-section to the beginning of the receipt of fresh charge in the cylinder and, therefore, leads to an improvement in the filling of the cylinders. In addition, due to the delay in closing the exhaust valve, the purge of the combustion chamber from residual gases is improved.
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Zaichenko, S., S. Korol, V. Opryshko, D. Derevyanko i N. Zhukova. "MODELING OF THE PROCESS OF ELECTROMECHANICAL CONTROL OF GAS DISTRIBUTION OF AN ELECTRIC ENERGY GENERATOR WITH AN INTERNAL COMBUSTION ENGINE". POWER ENGINEERING: economics, technique, ecology, nr 1 (11.10.2021): 51–58. http://dx.doi.org/10.20535/1813-5420.1.2021.242160.
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The use of generators at different load levels allows you to use part of the rated power of the engines, by reducing the speed of the internal combustion engine, thus reducing fuel consumption and increase the overall efficiency of the system as a whole. However, it should be noted that the optimal operation of the internal combustion engine at fixed gas distribution parameters is possible only at a certain engine speed. Reducing the engine speed leads to a deterioration of the filling of the fuel-air mixture and the release of exhaust gases from the engine, accompanied by the intake of exhaust gases into the intake manifold and the emission of part of the fuel
mixture into the exhaust pipe. The paper presents the results of the study of generator parameters and the general concept of creating an autonomous power supply control system based on an internal combustion engine in order to reduce the specific indicators of electricity generation. The expediency of regulating the power level of an internal combustion engine has been experimentally proved. To achieve this goal, it is proposed to adjust the opening and closing angles of the internal combustion engine with a solenoid valve. The use of this system allows to reduce the specific costs by more than 4 times when generating electricity with low generator load. Based on the phase distribution diagram of the internal combustion engine, the dependence of the change of the opening and closing angles of the inlet and outlet valves on the power of the autonomous energy source is proposed.
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Cui, Yi, Yilun Zhu i Kangyao Deng. "Study on the Operating Process of an Underwater Diesel Engine". Journal of Ship Research 52, nr 04 (1.12.2008): 239–48. http://dx.doi.org/10.5957/jsr.2008.52.4.239.
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A steady state and transient simulation model for an underwater diesel engine system, including governor, diesel engine, and pipe systems after turbine, is developed and verified. A two-phase flow of exhaust gas and water at the tail pipe is studied with three-dimensional fluid dynamics calculation. A water flooding criterion for an underwater engine is also given by these models and related experiments. Safe operation ranges of the engine are also studied. The histories of relative engine speed, pressure, and Froude number of the tail pipe exhaust gas under starting and stopping processes are studied. The Froude number of the tail pipe exhaust gas is an oscillating phenomena when the engine is starting, which is likely to cause sea water to flow backward into the tail pipe. The opening of the tongue valve must be controlled according to engine back pressure during the stopping process to prevent sea water flooding on the one hand and high back pressure on the other. The underwater diesel engine operating control strategy can be given on the basis of the research work.
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Song, Chang Qing, Jun Li, Da Wei Qu i Qi Jie Liu. "Simulation Study on Different Composition Fuels in Lean-Burn CNG Engine". Applied Mechanics and Materials 448-453 (październik 2013): 3430–33. http://dx.doi.org/10.4028/www.scientific.net/amm.448-453.3430.
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The Paper has Established a Combustion Model of Lean-Burn CNG Engine by Three-Dimensional Simulation Software AVL FRIE. Based on Test Validation in the Model, the Combustion Processes of Seven CNG Samples were Simulated and Compared from the Intake Valve Closed to the Exhaust Valve Opening. the Effects on Different Composition Fuels for CNG Engine were Researched. the Results Showed that: the Maximum Average Pressure within the Cylinder , the Highest Average Temperature, the Maximum Heat Release Rate, the Initial Mass Fraction of Fuels, CO and NO Formation Increased with the Hydrocarbon Fuel Ratio C/H, the Composition of Heavy Paraffin in CNG Directly Affected the Performance and Service Life of the Engine.
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Li, Weisong, Xuezhe Wei, Jiayuan Wang i Xueyuan Wang. "Construction of Nitrogen Content Observer for Fuel Cell Hydrogen Circuit Based on Anode Recirculation Mode". World Electric Vehicle Journal 14, nr 5 (20.05.2023): 131. http://dx.doi.org/10.3390/wevj14050131.
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The anode recirculation mode is increasingly being adopted in today’s fuel cell systems. The recycling of hydrogen gas can effectively improve fuel utilization and the wider economy. However, using the purge strategy for the recirculation exhaust has a significant impact on the operational performance and economic efficiency of fuel cell systems.Experiments have shown that, when the purge interval increases from 6 s to 10 s, the recirculation pump power increases by about 20%, the nitrogen content in the exhaust gas increases, and the stack voltage shows a 10 V attenuation. The accumulation of nitrogen permeation in the anode circuit leads to the degradation of the fuel cell performance. Therefore, it is necessary to discharge the accumulated nitrogen through the purge valve in a timely manner. However, opening the exhaust valve with excessively high frequency can result in the unreacted hydrogen being discharged, which reduces the economic efficiency of the fuel cell. This paper is based on the principle of mass conservation and models each subsystem of the anode circuit in the recirculation pump mode of the fuel cell separately, including the proportional valve model, the hydrogen consumption model of the fuel cell, the nitrogen permeation model of the fuel cell, the neural network model of the circulating pump, and the purge valve model. These submodels are integrated to construct a nitrogen content observer for the hydrogen circuit, which can estimate the nitrogen content. The accuracy of the model is validated through experimental data. The estimation error is less than 5.5%. The nitrogen content in the anode circuit can be effectively estimated, providing a model reference for purge operations and improving hydrogen utilization.
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Fathallah, Aguk Zuhdi Muhammad, i Anugrah Des Putra. "Experiment Study of Performance, Combustion Process, and NOX Emission of Diesel Engine with Air-Cooled Angle Globe Valve EGR". Advanced Engineering Forum 35 (luty 2020): 69–76. http://dx.doi.org/10.4028/www.scientific.net/aef.35.69.
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IMO ANNEX VI has enacted TIER III since 2016; one of the regulated emissions is NOX. The effective NOX reducing method is by using Exhaust Gas Recirculation (EGR). EGR valve with air-cooled angle globe valve type has been developed in Marine Diesel Laboratory, Department of Marine Engineering, Sepuluh Nopember Institute of Technology (ITS). EGR is in use on the Yanmar TF 85-MHDI diesel engine to study performance of engine, combustion processes, and NOX emitted experimentally. EGR varies from 0, 10, 20, and 30% respectively. To learn the performance of engine speed varied from 1800-2200 rpm. While the combustion process and NOX follow of IMO ANNEX VI. EGR without air cooling (HOT-EGR) is also studied for use as a reference of COLD-EGR achievement. The result of emission examine according to statistical data that modified diesel engine with HOT-EGR and COLD-EGR system are able to be within the threshold of emission test in TIER 2, at EGR valve opening 20% and 30% for load of 25%, 50%, and 75%. While for 100% load at EGR valve opening of 20% and 30%, the emission of diesel engine is capable of entering the TIER 3. In terms of performance the SFOC value can be improved on 10% of COLD-EGR condition with decrease of 14.62%, result for combustion process Peak pressure on the diesel engine becomes low and the heat release decreases.
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Bozza, Roberto, Vincenzo De Bellis, Stefano Fantoni i Donato Colangelo. "CFD 3D Analysis of Charge Motion and Combustion in a Spark-Ignition Internal Combustion Engine under Close-to-Idle Condition". E3S Web of Conferences 197 (2020): 06011. http://dx.doi.org/10.1051/e3sconf/202019706011.
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The increasingly stringent limitations on noxious missions of transport sector highly affect the development of new engines. The operating conditions of the engine at low-load and idle play a relevant role along the regulatory homologation cycles, contributing to overall emissions. In this work, the effectiveness of some solutions to improve the behaviour under close-to-idle operation of a Spark-Ignition motorcycle engine are compared by 3D CFD analyses. Specifically, the effects of two designs of the intake port and of the opening direction of the throttle valve, either clockwise or counterclockwise, are investigated. Multi-cycle simulations are carried out, under motored and fired conditions, for a single close-to-idle operating point. The various designs are compared in terms of capability to generate a stable tumble vortex during the intake phase and to produce an adequate turbulence level at the beginning of the combustion process. The analyses revealed that a clockwise throttle opening can produce enhanced turbulence levels at the end of the compression stroke, especially in a close-to-spark region (increase of about 5% and 27 % at the TDC at a global and local level, respectively, compared to the base configuration). Additional limited improvements are obtained with the high tumbling design, where, however, a penalty on the maximum power output could emerge. The flow and turbulence motion differences among the tested geometries reflect on combustion development in its early stage, and on its degree of completeness at the exhaust valve opening. A clockwise opening of the throttle valve leads to an increase of the mass fraction burned of 5 percent points, compared to the base configuration.
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Mohamad, M. N. A., W. S. I. W. Salim i W. N. A. W. Muhammad. "Feasibility study on the conversion of a small engine into a single-piston expander operating under different pressure and valve timing conditions". Journal of Physics: Conference Series 2312, nr 1 (1.08.2022): 012078. http://dx.doi.org/10.1088/1742-6596/2312/1/012078.
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Abstract There are limited studies on improving the piston expander performance for a wider operating range by adopting the variable valve timing method. This study uses a simple conversion technique to develop a single-piston expander (SPE) from a small two-stroke engine. The SPE is being tested at different operating conditions to study the feasibility of the SPE operating under different intake pressure and valve timing conditions. By fixing the exhaust valve timing, the SPE was tested at four intake pressure; 3, 4, 5, and 6 bar, while the intake valve closing varied from 30° to 110°. From the study, the highest power produced by the SPE was only 64 Watt when tested at 6 bar, with the intake valve opening at TDC and closed at 70°. The results show that the converted SPE is feasible in terms of functionality, but it is not performance-wise because much power has been lost through the recompression process. The study also observed that the intake valve timing could significantly affect the SPE power output, besides the intake pressure alone.
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Ala, Asman, Diah Zakiah i Faisal Fadly. "PERFORMANCE ANALYSIS OF WASTE GATE VALVE IN REGULATING EXhaust GAS FLOW TOWARDS THE TURBOCHARGER FOR THE FLEXIBLE COMBUSTION PROCESS ON THE TANGGUH JAYA LNG/C SHIP". Dinasti International Journal of Digital Business Management 2, nr 4 (27.07.2021): 618–24. http://dx.doi.org/10.31933/dijdbm.v2i4.907.
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A turbocharger is an auxiliary engine that functions to supply air into the cylinder and in general every turbocharger has two sides, namely, the compressor side and the turbine side, the rotation of the turbocharger is generated from the remaining exhaust gases from combustion in the cylinder which goes to the turbine side of the turbocharger and produces rotation. on that side and also rotates at the same speed on the compressor side of the turbocharger. The amount of air that will enter the cylinder depends on the rotation of the turbocharger itself, if the rotation of the turbocharger is too fast it will produce too much air in the cylinder which results in knocking or knocking on the main drive engine, whereas if the turbocharger rotates too slowly it will result in too little quantity of air resulting in a misfire or failure of combustion in the cylinder. To determine the rotational speed of the turbocharger, we need a tool that can regulate the quantity of the remaining exhaust gases from combustion in the cylinder, namely the waste gate valve. When the writer carried out the sea practice, the writer experienced various interesting things about the waste gate valve, such as the opening that did not match the degree of the waste gate valve to the difference in the indicator readings on the waste gate valve. In this case the author will analyze the cause of the imperfect supply of air entering the cylinder caused by the non-optimal performance of the waste gate valve.
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Lalić, Branko, Andrijana Poljak, Gojmir Radica i Antonija Mišura. "Low-Speed Marine Diesel Engine Modeling for NOx Prediction in Exhaust Gases". Energies 14, nr 15 (23.07.2021): 4442. http://dx.doi.org/10.3390/en14154442.
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Knowing the process of generating exhaust emissions and the determination of influential parameters are important factors in improving two-stroke slow-speed marine engines, particularly for further reductions in fuel consumption and stringent regulations on the limitation of nitrogen oxide emissions. In this article, a model of a marine low-speed two-stroke diesel engine has been developed. Experimental and numerical analyses of the nitrogen monoxide formations were carried out. When measuring the concentration of nitrogen oxides in the exhaust emissions, the amount of nitrogen dioxide (NO2) is usually measured, because nitrogen monoxide is very unstable, and due to the large amount of oxygen in the exhaust gases, it is rapidly converted into nitrogen dioxide and its amount is included in the total emission of nitrogen oxides. In this paper, the most significant parameters for the formation of nitrogen monoxide have been determined. Model validation was performed based on measured combustion pressures, engine power, and concentrations of nitrogen oxides at 50% and 75% of maximum continuous engine load. The possibilities of fuel consumption optimization and reduction in nitrogen monoxide emissions by correcting the injection timing and changing the compression ratio were examined. An engine model was developed, based on measured combustion pressures and scavenging air flow, to be used on board by marine engineers for rapid analyses and determining changes in the concentration of nitrogen oxides in exhaust emissions. The amount of nitrogen oxide in exhaust emissions is influenced by the relevant features described in this paper: fuel injection timing and engine compression ratio. The presented methodology provides a basis for further research about the simultaneous impact of changing the injection timing and compression ratio, exhaust valve opening and closing times, as well as the impact of multiple fuel injection to reduce consumption and maintain exhaust emissions within the permissible limits.
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Posylkin, M., A. M. K. P. Taylor, J. H. Whitelaw, K. Ishii i M. Miyano. "Measurements of Droplet Velocity and Size Downstream of the Moving Valves of a Four-Valve Engine With Manifold Injection, Operated Under Isothermal Steady Suction Conditions". Journal of Engineering for Gas Turbines and Power 119, nr 1 (1.01.1997): 250–56. http://dx.doi.org/10.1115/1.2815556.
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The four-valve head of a VTEC engine was mounted on an open cylinder and the valves and fuel injection system operated as in the engine with a rotational speed of 1200 rpm. Local measurements of droplet characteristics were obtained with a phase-Doppler velocimeter and iso-octane injected over 5 ms intervals, corresponding to 36 crank angle degrees, with manifold depression of 20 mbar. The results show that most of the fuel droplets were located close to the liner and on the side of the cylinder adjacent to the exhaust valves. In the plane of the measurement, 10 mm below TDC, the liquid flux diminished as the initiation of injection was advanced before opening of the inlet valves. With injection with the inlet valves closed, there were two waves of droplets, one from each of the two valves and separated by 60 deg CA and both with the Sauter mean diameter of about 120 μm. With injection with the inlet valves open, most of the droplets emerged from the main inlet valve and with Sauter mean diameters of about 50 μm, smaller than those of the unconfined spray.
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Gu, Wenyu, i Wanhua Su. "Study on the Effects of Exhaust Gas Recirculation and Fuel Injection Strategy on Transient Process Performance of Diesel Engines". Sustainability 15, nr 16 (15.08.2023): 12403. http://dx.doi.org/10.3390/su151612403.
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To meet increasingly stringent emission regulations, this study investigates the transient process of a heavy-duty diesel engine equipped with a two-stage turbocharger. The study focuses on analyzing the impact of the EGR system and fuel injection strategy during a transient process of a load increase (20% to 100% in 1 s) at a constant speed (1300 rpm). The research results showed that delaying the opening time of the high-pressure EGR valve from 0.1 s to 0.5 s reduces peak carbon soot emissions by 51.3%, with only a 3.13% increase in NOx emissions. By extending the high-pressure exhaust gas recirculation mixing length, the issue of an excessively high fuel–oxygen equivalence ratio caused by uneven exhaust gas mixing in individual cylinders can be avoided, resulting in a maximum reduction of 47.0% in peak soot emissions. Building on exhaust gas recirculation optimization, further modifications to the main and post-injection strategies led to a 28.1% reduction in soot emissions, a 4.73% decrease in peak NOx emissions, and a minor increase of 1.87% in the indicated fuel specific consumption compared to the single-injection strategy. The significant reduction in soot emissions will provide benefits for public health and environmental sustainability.
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Qi, Haonan, Hyoseo Kwak, Gunyoung Park, Beomgyu Kim i Chul Kim. "Design of Quadruple Offset Butterfly Valve Used in Power Plants". Applied Sciences 13, nr 6 (13.03.2023): 3656. http://dx.doi.org/10.3390/app13063656.
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The elliptical disc is a specific characteristic of a triple offset butterfly valve (TOBV), but the structure of the elliptical disc leads to a non-uniform distribution of contact at the closing position with non-uniform wear. On the other hand, the continuous processing of elliptical sections to finish the entire disc contour is expensive compared to the processing of a circular section. In the present study, to improve the above disadvantages of an elliptical disc, an elliptic cone function was established to describe the quadruple butterfly valve (QOBV) disc shape, which has a circular section disc. In addition, some designs of a fixed thickness (7 mm) laminated seal for good sealing were proved. Sealing performance simulations were carried out using the thermal–structural coupling analysis. The best design of the QOBV showed that the maximum contact pressure was 37.2% lower than the TOBV using the seven-way laminated seal layers (thickness of A240–316 stainless and graphite was 1.3 mm and 0.6 mm, respectively). Compared to TOBV, the QOBV disc operation during the opening and closing process was faster and smoother. The disc can be applied widely to various industrial fields, engine exhaust systems, and turbine and power plants under severe environments.
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Sasaki, H., S. Sekiyama i K. Nakashima. "A new combustion system of a heat-insulated natural gas engine with a pre-chamber having a throat valve". International Journal of Engine Research 3, nr 4 (1.08.2002): 197–208. http://dx.doi.org/10.1243/146808702762230905.
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A ceramic heat-insulated natural gas engine has been developed which incorporates a pre-chamber and a throat valve to the main chamber. Low-pressure natural gas is supplied into the pre-chamber to form fuel-rich mixtures in the pre-chamber during the intake stroke while the throat valve is closed, while natural gas and exhaust gas recirculation (EGR) gas are charged in the intake port to form a homogeneous mixture in the main chamber. Experiments showed that spontaneous ignition took place near top dead centre (TDC) in the pre-chamber immediately after the throat valve was opened, followed by homogeneous charge compression ignition (HCCI) combustion in the main chamber, featuring very fast combustion and extremely low NOX emission. Effects of engine parameters including compression ratio, throat valve opening timing, the fuel fraction injected into the pre-chamber and the EGR ratio were investigated. It was found from the experiment that 85 per cent of the fuel supplied could be successfully burned in HCCI combustion in the main chamber being triggered by the spontaneous ignition in the pre-chamber, and the HCCI combustion could be controlled if the engine parameters mentioned above could be well optimized.
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Seng, Lok Bee, Muhammad Ahmar Zuber, Wan Mohd Faizal Wan Mahmood, Zulkhairi Zainol Abidin i Zambri Harun. "Interpolation Techniques in Computational Particle Tracking inside a Direct-Injection Diesel Engine Cylinder". Applied Mechanics and Materials 663 (październik 2014): 381–86. http://dx.doi.org/10.4028/www.scientific.net/amm.663.381.
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Radial Basis Function (RBF) interpolation and trilinear interpolation techniques are compared in the soot particle tracking inside the cylinder of a direct injection engine. The interpolation techniques are used separately in an efficient routine written in Matlab codes which is developed to track the movement or pathline of soot particles in the engine operation cycle ranged from inlet valve closing (IVC) to exhaust valve opening (EVO). Soot particles are treated as a massless body and in spherical shape which will move under the influence of bulk gases flow inside the cylinder. Movement of soot particles are examined through the selection factors of particle's initial coordinate (r,Ɵ,z) and soot concentration level at different instant crack angle. Results obtained from both interpolation techniques are compared and good agreement is achieved with some minor relative difference. However, RBF interpolation has wider applications potential where it can be applied to variety type of mesh geometry as compared to trilinear interpolation which is best used in mesh with hexahedral shape.
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Vandevoorde, M., J. Vierendeels, R. Sierens, E. Dick i R. Baert. "Comparison of Algorithms for Unsteady Flow Calculations in Inlet and Exhaust Systems of IC Engines". Journal of Engineering for Gas Turbines and Power 122, nr 4 (17.04.2000): 541–48. http://dx.doi.org/10.1115/1.1288771.
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A comparison of different numerical algorithms used in commercial codes for the calculation of the one-dimensional unsteady flow in the pipes of the inlet and exhaust systems of internal combustion engines is presented in this work. The comparison is made between the Method Of Characteristics (MOC), different Lax-Wendroff schemes, first order upwind schemes and the newest TVD (Total Variation Diminishing) schemes. These algorithms are representative for the complete evolution noticed in the computer codes from the beginning of their use to the present state of the art. Two models of realistic problems in engine simulation tasks are considered: the shock tube calculation (so called Sod’s problem) and the calculation in a tapered pipe. The first test case simulates the exhaust valve opening and releasing a pressure (shock)wave in the exhaust manifold while the other test case covers any gradual variation in the cross section of the manifold pipes. For both test cases computed results are compared with an exact solution and computer time and accuracy are evaluated. None of the examined schemes is completely satisfactory. They either show too much overshoots (for the first test case), or they have local discretization errors (at the section changes of the second test case). A new TVD scheme is proposed that does not introduce any of the foregoing inaccuracies. With this scheme overshoots and dips are eliminated and mass balances are fulfilled, while maintaining high accuracy. [S0742-4795(00)00304-5]
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Adigamov, Nail, Andrey Negovora, Larisa Zimina i Alexey Maximov. "GAS DISTRIBUTION PHASES HYDRAULIC CONTROLLED INTERNAL COMBUSTION ENGINE VALVES". Vestnik of Kazan State Agrarian University 16, nr 4 (8.01.2022): 47–52. http://dx.doi.org/10.12737/2073-0462-2022-47-52.
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The efficiency of an agricultural car or tractor depends on the characteristics of the engine determined by the gas distribution mechanism (GRM). Traditional timing with fixed valve timing does not provide high-quality gas exchange at all engine operating modes. The aim of the work is to improve the characteristics of the engine by using the hydraulic drive of the timing valves. The drive allows you to turn off individual valves, set the moments of their opening and closing in an arbitrary way, provide several triggering of the internal combustion engine valves during the operating cycle. The drive is controlled by an electronic control unit (ECU). The advantage of the drive is its ease of integration into the internal combustion engine. The hydraulic drive ensures that the timing valves are lifted to a height of about 14 mm. The law of displacement of the valve, revealed experimentally, is close to trapezoidal. The use of a hydraulic valve drive has a positive effect on the "time-section" factor in the area of low and medium crankshaft rotational speeds. The increment of the factor "time-section" is due to the significant speeds of opening and closing the valves. Due to the peculiarities of the kinematic characteristics of the movement of the valves when using a hydraulic drive for their movement, the use of serial phases of gas distribution of the engine is impractical. Numerical modeling of the operation of the internal combustion engine determined the regularity of the change in valve timing from the high-speed operating mode of the engine. Optimization criterion is the achievement of maximum engine power. When choosing the valve timing, the possibility of meeting the intake and exhaust valves with the engine piston was excluded. The use of optimal phases leads to an increase in power up to 4.5% at a low crankshaft speed. With an increase in the speed mode, the increase in power decreases, and with a high frequency of rotation of the crankshaft, its slight decrease (1.4%) is observed. An increase in torque, up to a power utilization factor of 0.9, and its subsequent decrease, allow stabilizing the vehicle speed on a road with variable resistance. An increase in the working pressure in the hydraulic drive of the valves makes it possible to intensify gas exchange even at a high speed of rotation of the crankshaft
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Syaiful, S., i S. Sobri. "Efek Aditif LPM dan HPM Terhadap Konsumsi Bahan Bakar Spesifik (Brake Specific Fuel Consumption (BSFC)) dan Emisi Jelaga Mesin Diesel Injeksi Langsung Berbahan Bakar Campuran Solar dan Jatropha dengan Cold EGR (Exhaust Gas Recirculation)". REAKTOR 16, nr 3 (28.02.2017): 116. http://dx.doi.org/10.14710/reaktor.16.3.116-122.
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Diesel engines have been widely used as a mode of public transport and private vehicles because of several advantages compared to gasoline engines including greater power, fuel economy, high reliability and durability of the engine and lower CO emissions. However, diesel engines release more NOx and soot emissions into the atmosphere. This is a serious problem with the strict regulations regarding exhaust emissions. Besides problems of depletion of fossil fuel reserves require various parties to seek alternative fuels derived diesel fuel. Therefore, this work is intended to reduce soot emissions by adding LPM (low purity methanol) or wet methanol and HPM (high purity methanol) into a mixture of jatropha and diesel fuels. From this research, it is also desirable to observe the effect of methanol additive to the specific fuel consumption. Experiment method was conducted to obtain the correlation between the percentage of methanol to a brake specific fuel consumption (BSFC) and soot emissions. Methanol (LPM and HPM) was varied in the range of 5 to 15% by volume. Jatropha is in the range of 10% to 30%. The rate of EGR (exhaust gas recirculation) expressed by OEV (opening EGR valve) was varied at the opening of 0 to 100%. Engine load was varied from 25 to 100% at intervals of 25%. The engine speed was kept constant of 2000 rpm. The results show that the use of fuel mixture increases evenly BSFC of 5.2% and soot emissions of 65%. Keywords: LPM and HPM, BSFC, soot emissions, jatropha, cold EGR and diesel engine Abstrak Mesin diesel telah banyak digunakan sebagai moda transportasi umum dan kendaraan pribadi oleh karena beberapa kelebihannya dibandingkan dengan mesin bensin diantaranya daya yang lebih besar, hemat bahan bakar, kehandalan dan ketahanan mesin yang tinggi (high realibility and durability), dan emisi CO yang lebih rendah. Akan tetapi mesin diesel melepaskan lebih banyak emisi NOx dan jelaga ke atmosfir. Hal ini menjadi permasalahan serius dengan semakin ketatnya regulasi menyangkut emisi gas buang. Selain itu permasalahan menipisnya cadangan bahan bakar fosil menuntut berbagai pihak untuk mencari bahan bakar alternatif pengganti solar. Oleh karena itu, penelitian ini bermaksud untuk mereduksi emisi jelaga dengan menambahkan LPM (low purity methanol) atau wet methanol dan HPM (high purity methanol)kedalam campuran bahan bakar jatropha dan solar. Dari penelitian ini juga diinginkan untuk mengamati pengaruh aditif metanol terhadap konsumsi bahan bakar spesifik. Metode eksperimen dilakukan untuk mendapatkan keterkaitan antara prosentase metanol terhadap brake specific fuel consumption (BSFC)dan emisi jelaga. Metanol (LPM dan HPM) divariasikan pada rentang 5% sampai 15%. Jatropha adalah pada rentang 10% sampai 30%. Laju EGR (exhaust gas recirculation) yang dinyatakan oleh OEV (opening EGR valve) divariasikan pada bukaan 0% sampai 100%. Beban mesin divariasikan dari 25% sampai 100% dengan interval 25%. Putaran mesin dipertahankan konstan 2000 rpm. Hasil-hasil penelitian menunjukkan bahwa penggunaan bahan bakar campuran rata-rata meningkatkan BSFC 5,2% dan menurunkan emisi jelaga sampai 65%.