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Journal articles on the topic "Exhaust port analysis":
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Sun, Xing, Zhe Tian, Reza Malekian, and Zhixiong Li. "Estimation of Vessel Emissions Inventory in Qingdao Port Based on Big data Analysis." Symmetry 10, no. 10 (October 1, 2018): 452. http://dx.doi.org/10.3390/sym10100452.
Exhaust emissions from vessels have increasingly attracted attention in the continuously growing marine transport world trade market. The International Maritime Organization (IMO) has introduced a number of measures designed to reduce exhaust emissions from global shipping. As one of the busiest ports in the world, Qingdao port has been studied to propose possible support to the development of efficient emission reduction. In this study, a large amount data of emissions inventory in Qingdao port was used to predict its annual exhaust emissions, and hence, to help understand maritime pollution in Qingdao port. Bigdata analysis methodology was employed to perform accurate predictions on vessel emissions. The analysis results show that the emissions were dominated by container ships, oil tankers, and bulk cargo ships. The comparison between Qingdao port and other ports in emission control areas demonstrates the necessity of control measures for exhaust emissions. The adoption of shore power and efficient cargo handling seems to be a potential solution to reduce exhaust emissions. The findings of this study are meaningful for maritime safety administration to understand the current emission situation in Qingdao port, propose corresponding control measures, and perform pollution prevention.
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Rahman, M. M., Khalaf I. Hamada, Rosli A. Bakar, and M. A. Maleque. "Heat Transfer Analysis Inside Exhaust Port for a Hydrogen Fueled Port Injection Engine." Advanced Science Letters 14, no. 1 (July 1, 2012): 239–43. http://dx.doi.org/10.1166/asl.2012.4030.
Rahman, Md Mustafizur, Khalaf I. Hamada, M. M. Noor, K. Kadirgama, Rosli A. Bakar, and M. F. A. Rahim. "Heat Transfer Characteristics in Exhaust Port for Hydrogen Fueled Port Injection Engine: A Transient Approach." Advanced Materials Research 152-153 (October 2010): 1909–14. http://dx.doi.org/10.4028/www.scientific.net/amr.152-153.1909.
This paper was investigated the transient heat transfer characteristics in exhaust port for hydrogen fueled port injection internal combustion engine (H2ICE). One dimensional gas dynamics was described the flow and heat transfer in the components of the engine model. The engine model is simulated with variable engine speed and air fuel ratio (AFR). Engine speed varied from 2000 rpm to 5000 rpm with increment equal to 1000 rpm and AFR was varies from stoichiometric to lean limit. The effects of AFR and engine speed on heat transfer characteristics for the exhaust port are also investigated. The baseline engine model is verified with previous published results. The obtained results clarify that transient heat transfer process inside exhaust port for port injection H2ICE were affected by the engine speed and AFR. It can be seen that for obtained results clarify that for transient analysis, the fluctuation with very small amplitudes for heat transfer coefficient and heat transfer rate during the compression, intake and part of power stroke. The rapid change for both of them occurs during the exhaust and part of power stroke due to the exhaust valve is open. The obtained results from the simulation can be employed to examine the emission production and engine performance.
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Han, Dan, Zhi Xia He, Guo Jun Zhang, Shuo Wang, and Qian Wang. "Cold and Thermal Flow Field Analysis of Gasoline Engine Exhaust Port Based on CFD and RE." Advanced Materials Research 1079-1080 (December 2014): 918–21. http://dx.doi.org/10.4028/www.scientific.net/amr.1079-1080.918.
Exhaust passage is a significant part of the gasoline engine, its structure will affects the gas flow characteristics of the engine directly [1]. So, research and analysis of the exhaust tract is essential. In this paper, a detailed analysis of the flow field under cold state and hot state was made. For a start, the method of laser scanning and UG software were used to reverse modeling engine exhaust port and get the three-dimensional model. The next, the unstructured grid with local mesh refinement scheme was used to mesh this three-dimensional model with ICEM. After this, numerical simulations of the exhaust passage with five different valve lifts were carried out under thermal and cold conditions. Finally, comparing the velocity field and pressure field of the exhaust passage under cold state and thermal state, it can be find that the flow field under hot and cold state have similar characteristics. The results of this paper can provide a theoretical basis for following researches of the engine exhaust port.
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Liu, Fushui, Yang Xu, Jingmin Rui, Zhongjie Shi, and Yikai Li. "Flow Analysis and Theoretical Design of Diesel Engine Exhaust Port." International Journal of Automotive Technology 21, no. 1 (January 24, 2020): 189–96. http://dx.doi.org/10.1007/s12239-020-0019-6.
Bai, Yujie, Hong Ji, Yaozhuo Liu, Lei Li, and Shengqing Yang. "Analysis of Bubble Flow Mechanism and Characteristics in Gas–Liquid Cyclone Separator." Processes 9, no. 1 (January 8, 2021): 123. http://dx.doi.org/10.3390/pr9010123.
The separation of bubbles in a gas–liquid cyclone is complicated. A combination of numerical simulation and visual experimentation was considered apt to reveal the microscopic mechanisms of bubble flow. First of all, cyclones with different structures were numerically simulated. The calculation results show that the larger the diameter of the exhaust port, the better the bubble flow effect. When the exhaust port diameter was 24 mm, the gas discharge efficiency was 8% higher than that with an exhaust port diameter of 16 mm. The sequence of the bubble flow effect of a four-structure cyclone was obtained, and the gas discharge efficiency of the cyclone with a rectangular inlet was 7% higher than that of the trapezoidal inlet. Finally, a visual experimental platform was built to compare the rectangular inlet cyclone and spiral inlet cyclone with the best bubble flow effect. In accordance with the simulation numerical calculations, the bubble flow effect of the rectangular inlet cyclone was better than that of the spiral and trapezoid inlet cyclones, and the rectangular inlet in the middle was better. This article provides a specific theory and experience to guide further research on the separation mechanism, flow field characteristics and structurally optimal design of gas–liquid cyclones.
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Bai, Yujie, Hong Ji, Yaozhuo Liu, Lei Li, and Shengqing Yang. "Analysis of Bubble Flow Mechanism and Characteristics in Gas–Liquid Cyclone Separator." Processes 9, no. 1 (January 8, 2021): 123. http://dx.doi.org/10.3390/pr9010123.
The separation of bubbles in a gas–liquid cyclone is complicated. A combination of numerical simulation and visual experimentation was considered apt to reveal the microscopic mechanisms of bubble flow. First of all, cyclones with different structures were numerically simulated. The calculation results show that the larger the diameter of the exhaust port, the better the bubble flow effect. When the exhaust port diameter was 24 mm, the gas discharge efficiency was 8% higher than that with an exhaust port diameter of 16 mm. The sequence of the bubble flow effect of a four-structure cyclone was obtained, and the gas discharge efficiency of the cyclone with a rectangular inlet was 7% higher than that of the trapezoidal inlet. Finally, a visual experimental platform was built to compare the rectangular inlet cyclone and spiral inlet cyclone with the best bubble flow effect. In accordance with the simulation numerical calculations, the bubble flow effect of the rectangular inlet cyclone was better than that of the spiral and trapezoid inlet cyclones, and the rectangular inlet in the middle was better. This article provides a specific theory and experience to guide further research on the separation mechanism, flow field characteristics and structurally optimal design of gas–liquid cyclones.
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Ziemska, Monika. "Exhaust Emissions and Fuel Consumption Analysis on the Example of an Increasing Number of HGVs in the Port City." Sustainability 13, no. 13 (July 2, 2021): 7428. http://dx.doi.org/10.3390/su13137428.
Due to the increase in cargo handling in ports, and the thereby increase of trucking directly associated with them, this article examines the impact of heavy goods vehicles generated by the port facilities on the environment. The article determines what is feasible to limit the percentage increase in the number of HGVs generated by the port areas such as container terminals or mass, which will result in a significant increase in emissions in the port city. In this study, five intersections were analyzed using micro-simulation to determine exhaust emissions such as CO, NOx, VOC, and fuel consumption. The analysis was made on the example of the port city of Gdynia in Poland, using the actual data. The use of the PTV Vissim tool made it possible to obtain the result data from the simulation of ten variants with a variant representing the current state. The results indicate that increasing the number of HGVs generated by port areas by 40% will make a significant difference in exhaust emissions. The obtained results can be useful for controlling the level of environmental pollution as predictive models.
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Pitta, Srinivasa, and Rajagopal Kuderu. "A computational fluid dynamics analysis on stratified scavenging system of medium capacity two-stroke internal combustion engines." Thermal Science 12, no. 1 (2008): 33–42. http://dx.doi.org/10.2298/tsci0801033p.
The main objective of the present work is to make a computational study of stratified scavenging system in two-stroke medium capacity engines to reduce or to curb the emissions from the two-stroke engines. The 3-D flows within the cylinder are simulated using computational fluid dynamics and the code Fluent 6. Flow structures in the transfer ports and the exhaust port are predicted without the stratification and with the stratification, and are well predicted. The total pressure and velocity map from computation provided comprehensive information on the scavenging and stratification phenomenon. Analysis is carried out for the transfer ports flow and the extra port in the transfer port along with the exhaust port when the piston is moving from the top dead center to the bottom dead center, as the ports are closed, half open, three forth open, and full port opening. An unstructured cell is adopted for meshing the geometry created in CATIA software. Flow is simulated by solving governing equations namely conservation of mass momentum and energy using SIMPLE algorithm. Turbulence is modeled by high Reynolds number version k-e model. Experimental measurements are made for validating the numerical prediction. Good agreement is observed between predicted result and experimental data; that the stratification had significantly reduced the emissions and fuel economy is achieved.
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Latheesh, V. M., P. Parthasarathy, V. Baskaran, and S. Karthikeyan. "Design and CFD analysis of intake port and exhaust port for a 4 valve cylinder head engine." IOP Conference Series: Materials Science and Engineering 310 (February 2018): 012122. http://dx.doi.org/10.1088/1757-899x/310/1/012122.
Dissertations / Theses on the topic "Exhaust port analysis":
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Tailony, Rauf. "Internal Combustion Engine Cold Test Driveline Modeling, Analysis and Development." University of Toledo / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1564765172535669.
Bergel, André. "Numerical analysis of exhaust gas aftertreatment in spark ignition engines." Instituto Tecnológico de Aeronáutica, 2014. http://www.bd.bibl.ita.br/tde_busca/arquivo.php?codArquivo=3146.
This dissertation describes the known formation mechanisms of pollutant emissions for spark ignition internal combustion engines, the most common pollutants emitted by spark ignition engines, current methods to reduce pollutants emissions and a comparison of industry procedures with one and three-dimensional modeling including detailed surface reaction chemistry model, all used to estimate catalytic converter efficiency. Also, experimental tests were performed to provide exhaust gas composition boundary conditions, and to provide values for current catalytic converter efficiency. The detailed surface reaction chemistry model presented problems into implementation for one and three-dimensional analyzes, presenting zero conversion into one-dimensional analysis and continuous reduction in conversion efficiency for three-dimensional analysis. The industry procedure has been used for a long time, and presented the more realist values and behavior, not justifying the replacement for an analysis that includes chemistry reaction models, either one or three-dimensional.
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Chen, C. L., and 陳佳良. "The Measurement and Analysis of the Instant Air Flow in the Exhaust Pipe and Intake Port for Single Cylinder engine." Thesis, 2001. http://ndltd.ncl.edu.tw/handle/33002805725733475588.
碩士 國立中興大學 機械工程學系 89 The computational fluid dynamics (CFD) was used in this study to investigate the flow characteristics in the engine inlet and exhaust system. The inlet flow was a steady flow simulating the flow bench test measuring the flow coefficient of inlet valve. The exhaust flow was a pulsating flow simulating engine running at constant speeds. A commercial software package PHOENICS was used in this study.
In the inlet flow study, the CAD file of the engine was input to PHOENICS to generate the necessary geometric configuration of the intake system. It was found that grid size and the boundary condition at the inlet were the primary factors to affect the results of calculation. The flow rates at high valve lift were 5% lower than the measured data. However, at low vale lift, the deviations were as high as 25%. The discrepancy can be attributed to that the structured type grid system did not quite fit to the complex geometry of inlet system.
A simplified exhaust pipe with two expansion chambers was used in the exhaust flow study. The velocity distributions obtained from numerical calculation were close to measured data, which were obtained with a hot wire anemometer. It was found that circulating zones emerged at the corner of the first expansion chamber, and transported down streams, and then decayed. The computing result also showed that the distribution of pressure in the exhaustion tube was one-dimensional.
The turbulence intensities as well as the cyclic variations of the flow in the expansion chamber were also measured with hot wire anemometer. It was found that high turbulence flow concentrated in the second expand chamber.
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chen, Liao wei, and 廖偉成. "The Analysis of the Steady Flow in the Intake Port and Exhaust Pipe for Single Cylinder engine and Flow Characteristics of Catalysts." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/38773625960123262242.
碩士 國立中興大學 機械工程學系 91 The computational fluid dynamics (CFD) was used in this study to investigate the flow characteristics in the engine inlet and exhaust system. The inlet flow was a steady flow simulating the flow bench test measuring the flow coefficient of inlet valve. A commercial software package FLUENT was used in this study.
In the inlet flow study, the CAD file of the engine was transformed to IGES and STL formulation, and IGES and STL file was imported into FLUENT to generate unstructured mesh. In order to build up unstructured mesh, the transformation of CAD file was the topic in this study. It was found results of unstructured mesh close to measured data at low valve lift. However, at high vale lift, the deviation was 8.9%.
A real exhaust system model was used in this study. The component of exhaust pipe was sat dividedly. It was convenient to change position or size of exhaust component. The computing result showed that the distribution of pressure in the exhaustion chamber was uniform.
A long tube was assumed to simulate the pipe in the platinum catalyst. The kinetics of carbon monoxide and propylene oxidation were discussed in this study. The five parameters were took into consideration. The computing result showed that wall temperature and pipe diameter was the most influential parameters.
Books on the topic "Exhaust port analysis":
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Hoyle, Carolyn, and Mai Sato. Reasons to Doubt. Oxford University Press, 2019. http://dx.doi.org/10.1093/oso/9780198794578.001.0001.
This book reveals what happens to applications for post-conviction review when those in England and Wales who consider themselves to have been wrongfully convicted, and have exhausted direct appeal processes, apply to have their case assessed by the Criminal Cases Review Commission. It presents the findings of the first thorough empirical study of decision-making and the use of discretion within the Commission. It shows how the Commission exercises its discretionary powers in identifying and investigating possible wrongful convictions for rehearing by the Court of Appeal. The research it draws on — a three year empirical study — comprises a mixed-method approach of quantitative and qualitative analysis of case files and aggregate data, as well as interviews with decision makers and observations of committee meetings to fully grasp the workings of the organisation from a socio-legal perspective and to understand how discretion operates at the individual and institutional level.
Book chapters on the topic "Exhaust port analysis":
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Biewer, Sebastian, Bernd Finkbeiner, Holger Hermanns, Maximilian A. Köhl, Yannik Schnitzer, and Maximilian Schwenger. "RTLola on Board: Testing Real Driving Emissions on your Phone." In Tools and Algorithms for the Construction and Analysis of Systems, 365–72. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-72013-1_20.
AbstractThis paper is about shipping runtime verification to the masses. It presents the crucial technology enabling everyday car owners to monitor the behaviour of their cars in-the-wild. Concretely, we present an Android app that deploys rtlola runtime monitors for the purpose of diagnosing automotive exhaust emissions. For this, it harvests the availability of cheap bluetooth adapters to the On-Board-Diagnostics (obd) ports, which are ubiquitous in cars nowadays. We detail its use in the context of Real Driving Emissions (rde) tests and report on sample runs that helped identify violations of the regulatory framework currently valid in the European Union.
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"Coolant Leakage Through a Cylinder-Head Exhaust Port Caused by Shrinkage Porosity." In ASM Failure Analysis Case Histories: Automobiles and Trucks. ASM International, 2019. http://dx.doi.org/10.31399/asm.fach.auto.c0047263.
Conference papers on the topic "Exhaust port analysis":
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Gennish, R., J. Jiang, A. Albarbar, G. Harris, F. Gu, and A. Ball. "Diesel Engine Combustion Monitoring Based on Acoustic Measurement of Exhaust Systems." In ASME 8th Biennial Conference on Engineering Systems Design and Analysis. ASMEDC, 2006. http://dx.doi.org/10.1115/esda2006-95648.
This paper presents a novel monitoring approach to diesel engine combustion based on acoustic measurement of exhaust systems. It investigates the acoustic characteristics from the measurements of individual sensors and their combination based on a linear one port acoustic source model. It has been found that the strength, in terms of pressure, of the acoustic source gives a more accurate representation of engine acoustics because it is obtained by minimizing the reflection effects in the exhaust system. Therefore, the pressure waveform produces more accurate monitoring results for abnormal combustions such as those caused by faults in engine fuel injection systems.
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Huang, David T. Y., David K. S. Chen, and David L. Van Ostrom. "Finite Element Reliability Analysis of a Ceramic Exhaust Port Liner Subjected to Thermomechanical Interactions During Casting." In SAE International Congress and Exposition. 400 Commonwealth Drive, Warrendale, PA, United States: SAE International, 1988. http://dx.doi.org/10.4271/880678.
Gaikwad, Surendra, Nameer Salman, and Saad Umer. "Charge Motion Analysis to Guide Engine Port Development and Enhance Combustion Stability for High Cooled Exhaust Gas Recirculation." In SAE 2013 World Congress & Exhibition. 400 Commonwealth Drive, Warrendale, PA, United States: SAE International, 2013. http://dx.doi.org/10.4271/2013-01-1313.
Sengupta, Jeet, Mohammad Abbaspour, and Kirby S. Chapman. "Assessing the Impact of Pressure Pulses in Exhaust Manifold During Blowdown Process on In-Cylinder Distribution Using T-RECS." In ASME 2007 Internal Combustion Engine Division Fall Technical Conference. ASMEDC, 2007. http://dx.doi.org/10.1115/icef2007-1635.
In an internal combustion engine, both the two-stroke and the four-stroke variety, the ejection of exhaust gases from the cylinder is termed as blowdown. In a two stroke engine, during blowdown the in-cylinder gases which are at a pressure higher than the exhaust manifold pressure rush out of the exhaust port into the manifold, resulting in a high pressure wave propagating through the manifold. In a multi-cylinder engine where the exhaust ports of each cylinder are connected to the manifold, the high pressure pulses in the manifold will impact the in-cylinder performance of the cylinders downstream of the first cylinder. This impact was investigated using the Turbocharger Reciprocating Engine Computer Simulation (T-RECS), a zero-dimensional cycle simulation tool developed at the National Gas Machinery Laboratory (NGML). The manifold pressure distributions were generated using the NGML developed Virtual Pipeline Simulation Tool (VPST), which is a one-dimensional pipe flow simulation software package. The analysis assumed that at any given instant the exhaust port of only one cylinder is open while the exhaust ports of all other cylinders remain closed. The results showed that the in-cylinder pressure distributions could become significantly altered under the influence of the exhaust manifold pressure pulses. The knowledge gained would help in utilizing the pressure pulses more effectively in tuning the exhaust manifold.
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Yamada, Kentaro, Akiyoshi Iida, and Akisato Mizuno. "Numerical Estimation of Exhaust Gas Emission From Tunnel Portal With Forced Extraction System." In ASME/JSME 2007 5th Joint Fluids Engineering Conference. ASMEDC, 2007. http://dx.doi.org/10.1115/fedsm2007-37126.
In recent years, exhaust gas emission out of tunnel portals has been a problem. In order to maintain the environment around the tunnel portal, a concentrated exhaustion system is installed in some tunnels. In the area between the suction port and the portal, the air flows in the opposite direction to the traffic, so that the pollutant is sucked toward the exhaustion port. In order to grasp the detailed phenomena, the authors investigated quantitatively the extent of the pollutant, which is brought out of the tunnel portal, in terms of a three-dimensional numerical analysis. This simulation system includes a sliding mesh algorithm in order to express the movement of vehicles. A typical result of the suction velocity of 1.0 m/s showed that almost no emission out of the tunnel is observed in small car traffic.
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Stuart, Kurt, Terry Yan, and James Mathias. "Analysis of a 5-Stroke Engine With a Two-Zone Equilibrium Combustion Products Model." In ASME 2019 Internal Combustion Engine Division Fall Technical Conference. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/icef2019-7206.
Abstract A 5-stroke engine was analyzed using an improved 2-zone combustion model utilizing an equilibrium combustion model to calculate the gas properties in each zone. The flows of inlet, exhaust, and transfer port are handled using quasi-steady 1-D flow models. Heat transfer in the transfer port is also considered. The results are reported as indicated thermal efficiency and power output over a range of operating points and design characteristics, including engine RPM, compression ratio, overall expansion ratio, expansion cylinder clearance volume, and transfer port volume. It was found that the transfer port volume had a significant effect on the overall indicated thermal efficiency. The results were compared with those of a baseline 4-stroke engine. The 5-stroke engine with a compression ratio of 9:1, and an overall expansion ratio of 27:1 achieves a peak indicated thermal efficiency of 47%, representing a 6% increase over the baseline 4-stroke engine with the same compression ratio.
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Turner, J. W. G., R. A. Head, R. Wijetunge, J. Chang, N. Engineer, D. W. Blundell, and P. Burke. "Analysis of Different Uniflow Scavenging Options for a Medium-Duty 2-Stroke Engine for a U.S. Light-Truck Application." In ASME 2018 Internal Combustion Engine Division Fall Technical Conference. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/icef2018-9766.
The work presented here seeks to compare different means of providing uniflow scavenging for a 2-stroke engine suitable to power a US light-duty truck. Through the ‘end-to-end’ nature of the uniflow scavenging process, it can in theory provide improved gas-exchange characteristics for such an engine operating cycle; furthermore, because the exhaust leaves at one end and the fresh charge enters at the other, the full circumference of the cylinder can be used for the ports for each flow and therefore, for a given gas exchange angle-area demand, expansion can theoretically be maximized over more traditional loop-scavenging approaches. This gives a further thermodynamic advantage. The three different configurations studied which could utilize uniflow scavenging were the opposed piston, the poppetvalve with piston-controlled intake ports and the sleeve valve. These are described and all are compared in terms of indicated fuel consumption for the same cylinder swept volume, compression ratio and exhaust pressure, for the same target indicated mean effective pressure and indicated specific power. A new methodology for optimization was developed using a one-dimensional engine simulation package which also took into account charging system work. The charging system was assumed to be a combination of supercharger and turbocharger to permit some waste energy recovery. As a result of this work it was found that the opposed-piston configuration provides the best attributes since it allows maximum expansion and minimum heat transfer. Its advantage over the other two (whose results were very close) was of the order of 8.3% in terms of NSFC (defined as ISFC net of supercharger power). Part of its advantage also stems from its requirement for minimum air supply system work, included in this NSFC value. Interestingly, it was found that existing experiential guidelines for port angle-area specification for loop-scavenged, piston-ported engines using crankcase compression could also be applied to all of the other scavenging types. This has not been demonstrated before. The optimization process that was subsequently developed allowed port design to be tailored to specific targets, in this case lowest NSFC. The paper therefore presents a fundamental comparison of scavenging systems using a new approach, providing new insights and information which have not been shown before.
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Hamilton, Leonard J., and Jim S. Cowart. "Cold Engine Transient Fuel Control Experiments in a Port Fuel Injected CFR Engine." In ASME 2007 Internal Combustion Engine Division Fall Technical Conference. ASMEDC, 2007. http://dx.doi.org/10.1115/icef2007-1696.
Air-fuel mixture preparation is particularly challenging during cold engine throttle transients due to poor fuel vaporization and transport delays in port fuel injected (PFI) engines. In this study, a PFI Cooperative Fuels Research engine is used to evaluate torque and measure in cylinder and exhaust CO, CO2 and unburned hydrocarbons during throttle transients at various early stages of engine warm-up. Fast flame ionization detectors and non-dispersive infra-red fast CO and CO2 detectors are used to provide detailed cycle-by-cycle analysis. Torque after cold throttle transients is found to be comparable to steady state torque due to allowable spark advance. However, cold transients produce up to 4 times the unburned hydrocarbons when compared to steady state operation. Finally, the x-tau fuel control model is evaluated in this challenging operating regime and is found to provide poor transient fuel control due to excessive fueling.
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Andersen, Fredrik Herland, and Stefan Mayer. "Parametric Study of the Scavenging Process in Marine Two-Stroke Diesel Engines." In ASME 2015 Internal Combustion Engine Division Fall Technical Conference. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/icef2015-1075.
Large commercial ships such as container vessels and bulk carriers are propelled by low-speed, uniflow scavenged two-stroke diesel engines. The integral in-cylinder process in this type of engine is the scavenging process, where the burned gas from the combustion process is evacuated through the exhaust valve and replaced with fresh air for the subsequent compression stroke. The scavenging air enters the cylinder via inlet ports which are uncovered by the piston at bottom dead center (BDC). The exhaust gas is then displaced by the fresh air. The scavenging ports are angled to introduce a swirling component to the flow. The in-cylinder swirl is beneficial for air-fuel mixture, cooling of the cylinder liner and minimizing dead zones where pockets of exhaust gas are trapped. However, a known characteristic of swirling flows is an adverse pressure gradient in the center of the flow, which might lead to a local deficit in axial velocity and the formation of central recirculation zones, known as vortex breakdown. This paper will present a CFD analysis of the scavenging process in a MAN B&W two-stroke diesel engine. The study include a parameter sweep where the operating conditions such as air amount, port timing and scavenging pressure are varied. The CFD model comprise the full geometry from scavenge receiver to exhaust receiver. Asymmetric inlet and outlet conditions is included as well as the dynamics of a moving piston and valve. Time resolved boundary conditions corresponding to measurements from an operating, full scale production, engine as well as realistic initial conditions are used in the simulations. The CFD model provides a detailed description of the in-cylinder flow from exhaust valve opening (EVO) to exhaust valve closing (EVC). The study reveals a close coupling between the volume flow (delivery ratio) and the in-cylinder bulk purity of air which appears to be independent of operating conditions, rpm, scavenge air pressure, BMEP etc. The bulk purity of air in the cylinder shows good agreement with a simple theoretical perfect displacement model.
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Alam, Shah Saud, and Christopher Depcik. "Adaptive Wiebe Function Parameters for a Port-Fuel Injected Hydrogen-Fueled Engine." In ASME 2019 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/imece2019-10031.
Abstract Current unmanned aerial vehicle (UAV) propulsion technologies includes hydrogen fuel cells, battery systems, and internal combustion engines (ICE). However, relying on a single propulsion technology might result in a limited operational range. This can be mitigated by utilizing a hybrid configuration involving a battery pack and an ICE or a fuel cell for charging. Due to its significant weight advantage and high mass-specific energy content, hydrogen (H2) is an ideal fuel for both power plant options. However, use of H2 with an ICE requires precise operational control through combustion process simulation with the predictive approximation of the mass fraction burned profile. In this area, the relatively simple single-Wiebe function is widely deployed for a variety of different fuels, as well as combustion regimes. In general, the description of the single-Wiebe function includes the extent of complete combustion (a), magnitude of the maximum burn rate (m), and combustion duration (θd). However, the literature often provides values for these parameters without necessarily relating them to operational characteristics that can influence ICE power. As a result, it is critical to correlate the burn rate of the fuel to ICE operating parameters, such as the engine compression ratio, inlet pressure, mean piston speed, exhaust gas recirculation level, equivalence ratio, and spark timing. Therefore, in an attempt to physically define these parameters, this effort performs a sensitivity analysis using linear regression (least squares method) to assess the impact of engine operating conditions on the Wiebe function in comparison to experimental data for port-fuel injected hydrogen ICEs. The result is a model that can estimate the values of a, m, and θd in combination with a relatively high coefficient of determination (R2) when compared to the experimental mass fraction burned profiles. Finally, others can expand this methodology to any experimental data for engine and fuel-specific Wiebe parameter determination.
