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Special Issue "Recent Advances in Internal Combustion Engines Operation and Emissions"

A special issue of Energies (ISSN 1996-1073).

Deadline for manuscript submissions: 31 December 2018

Special Issue Editor

Guest Editor
Prof. Dr. Evangelos G. Giakoumis
Highly Cited - Clarivate Analytics (formerly Thomson Reuters)

School of Mechanical Engineering, National Technical University of Athens, Athens, Greece
Website | E-Mail
Interests: diesel engine performance and emissions during transient operation; turbocharging; transient cycles; use of biofuels in engines; second-law analysis of IC Engines; engine friction; combustion noise

Special Issue Information

Dear Colleagues,

Internal combustion (I.C.) engines, either in the form of compression ignition (diesel) or spark ignition (SI), have dominated the transportation sector (road, locomotive and marine) for many decades. The ability of an I.C. engine to operate efficiently over a wide range of speeds and loads, as well as its good drivability, have been major contributing factors to this dominance over other thermal engines. It is not surprising then that research on I.C. engines has been vigorous, both on simulation and experimental bases. Nowadays, the main objectives are the minimization of fuel consumption/CO2 emissions and the mitigation of exhaust pollutants. To this aim, various alternative combustion techniques have been developed, or are under development (e.g., direct injection SI engines, HCCI operation etc.); various internal and after-treatment exhaust measures are also being examined.

One particular aspect of (automotive) engines is dynamic operation, being responsible for the largest amount of emitted pollutants; acknowledging this fact, the certification (both driving and engine) cycles for all kinds of vehicles are highly transient.

Another significant aspect of modern engines is their supercharging, realized mainly through various turbocharging configurations. Today, turbocharging an I.C. engine is a well-established means for achieving lower CO2 emission targets, as is also the use of hybrid electric powertrains.

In parallel, the use of alternative fuels and biofuels has boomed in the last few decades, as these have proven to be promising in limiting carbonaceous pollutants emissions, while, at the same time, providing a positive CO2 balance.

The present Special Issue of Energies aims to gather innovative simulations and experimental research, and highlight recent advances on various aspects of internal combustion engine operation, such as those mentioned above. More specifically, topics of interest for the Special Issue include (but are not limited to):

  • Combustion mechanisms in spark and compression ignition engines;
  • Fuel injection and spray formation;
  • Pollutants formation (particulate matter, NOx, CO, HC, noise);
  • Exhaust after-treatment systems (three-way catalysts, oxidation catalysts, diesel and gasoline particulate filters, SCR, NOx adsorbers);
  • Internal measures for emission control (EGR, water injection, etc);
  • Performance and emissions during certification (driving and engine) cycles;
  • Transient engine operation;
  • Turbocharging;
  • Alternative fuels and biofuels effects on engine performance and emissions (ethanol, butanol, biodiesel, dimethylether, Fischer Tropsch, etc.);
  • Recent advances in internal combustion engines experimentation;
  • Novel combustion systems (HCCI, PCCI and RCCI);
  • Hybrid electric engine operation;
  • Second-law analysis of engines.

Prof. Dr. Evangelos Giakoumis
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Energies is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Published Papers (13 papers)

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Research

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Open AccessArticle Real-World Fuel Consumption, Fuel Cost and Exhaust Emissions of Different Bus Powertrain Technologies
Energies 2018, 11(8), 2160; https://doi.org/10.3390/en11082160
Received: 17 July 2018 / Revised: 11 August 2018 / Accepted: 15 August 2018 / Published: 18 August 2018
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Abstract
Air quality in urban areas is strongly influenced by exhaust emitted by the public transport fleet. The aim of this study was to analyze benefits in the fuel consumption, fuel costs and exhaust emissions when replacing baseline diesel fueled EURO III city buses
[...] Read more.
Air quality in urban areas is strongly influenced by exhaust emitted by the public transport fleet. The aim of this study was to analyze benefits in the fuel consumption, fuel costs and exhaust emissions when replacing baseline diesel fueled EURO III city buses by the compressed natural gas (CNG)-fueled EURO V buses and by hydraulic series hybrid diesel-fueled EURO V buses. Real-world measurements were performed on the regular bus route to access realistic energy consumption and exhaust emissions. Instantaneous gaseous emission (CO2, CO, NOx and THC) were measured together with the instantaneous PM10 mass emission. Innovativeness of the presented approach thus arises from the systematic comparison of different powertrain technologies under real-world drive cycles and measuring time traces of not only gaseous but also of PM10 mass emissions. Furthermore, lumped cycle averaged emissions are interpreted and explained by typical powertrain performance parameters and exhaust emission time traces. Cumulative results indicate that application of the CNG fueled buses does not necessary reduce CO2 emissions compared to diesel-fueled buses whereas reduction in fuel costs is evident. Additionally, it is shown that hybrid operation of the hydraulic series hybrid diesel-fueled bus resulted in higher fuel consumption due to poorly optimized hybrid topology and control strategy. Furthermore, analyses of the time traces point out inadequate lambda control of CNG-fueled buses and nucleation mode-based particle number emissions during deceleration. Full article
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Open AccessArticle Macroscopic and Microscopic Spray Characteristics of Diesel and Gasoline in a Constant Volume Chamber
Energies 2018, 11(8), 2056; https://doi.org/10.3390/en11082056
Received: 30 June 2018 / Revised: 27 July 2018 / Accepted: 6 August 2018 / Published: 8 August 2018
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Abstract
The aim of this study is to investigate the spray characteristics of diesel and gasoline under various ambient conditions. Ambient conditions were simulated, ranging from atmospheric conditions to high pressure and temperature conditions such as those inside a combustion chamber of an internal
[...] Read more.
The aim of this study is to investigate the spray characteristics of diesel and gasoline under various ambient conditions. Ambient conditions were simulated, ranging from atmospheric conditions to high pressure and temperature conditions such as those inside a combustion chamber of an internal combustion engine. Spray tip penetration and spray cross-sectional area were calculated in liquid and vapor spray development. In addition, initial spray development and end of injection near nozzle were visualized microscopically, to study spray atomization characteristics. Three injection pressures of 50 MPa, 100 MPa, and 150 MPa were tested. The ambient temperature was varied from 300 K to 950 K, and the ambient density was maintained between 1 kg/m3 and 20 kg/m3. Gasoline and diesel exhibited similar liquid penetration and spray cross-sectional area at every ambient density condition under non-evaporation. As the ambient temperature increased, liquid penetration length and spray area of both fuels’ spray were shortened and decreased by fuel evaporation near the spray boundary. However, the two fuels were characterized by different slopes in the decrement trend of spray area as the ambient temperature increased. The decrement slope trend coincided considerably with the distillation curve characteristics of the two fuels. Vapor spray boundary of gasoline and diesel was particularly similar, despite the different amount of fuel evaporation. It was assumed that the outer spray boundary of gasoline and diesel is always similar when using the same injector and injection conditions. In microscopic spray visualization, gasoline spray displayed a more unstable and asymmetric spray shape, with more dispersed and distributed fuel ligaments during initial spray development. Large amounts of fuel vapor cloud were observed near the nozzle at the end of the injection process with gasoline. Some amounts of this vapor cloud were attributed to the evaporation of residual fuel in the nozzle sac. Full article
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Open AccessArticle On the Effect of a Rail Pressure Error State Observer in Reducing Fuel Injection Cycle-to-Cycle Variation in an Opposed-Piston Compression Ignition Engine
Energies 2018, 11(7), 1729; https://doi.org/10.3390/en11071729
Received: 28 May 2018 / Revised: 12 June 2018 / Accepted: 13 June 2018 / Published: 2 July 2018
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Abstract
The fuel injection cycle-to-cycle variation characteristic in an opposed-piston compression ignition engine was investigated experimentally. Based on the optimal Proportion Integration Differentiation (PID) method, a new control method was proposed by utilizing a rail pressure error state observer (OBS) before feedback. Compared with
[...] Read more.
The fuel injection cycle-to-cycle variation characteristic in an opposed-piston compression ignition engine was investigated experimentally. Based on the optimal Proportion Integration Differentiation (PID) method, a new control method was proposed by utilizing a rail pressure error state observer (OBS) before feedback. Compared with the conventional filtering treatment method, the OBS method was developed to simultaneously account for the flow mass changing and the dynamics of a common rail system, rather than representing the rail pressure state as an average value over a period time. The OBS method was subsequently implemented in the control system to investigate the injection pressure oscillation characteristic and cycle-to-cycle variation of injected fuel quantity. The results show that the present OBS method substantially reduces the injection pressure oscillation, improves response characteristics of the control system, and produces qualitatively satisfactory fuel injection cycle-to-cycle variation in the opposed-piston compression ignition (OPCI) engine. Full article
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Open AccessArticle Study on Fuel Distribution of Wall-Impinging Diesel Spray under Different Wall Temperatures by Laser-Induced Exciplex Fluorescence (LIEF)
Energies 2018, 11(5), 1249; https://doi.org/10.3390/en11051249
Received: 9 April 2018 / Revised: 25 April 2018 / Accepted: 26 April 2018 / Published: 14 May 2018
Cited by 1 | PDF Full-text (3576 KB) | HTML Full-text | XML Full-text
Abstract
Spray wall-impingement has large effects on the pollutant emissions and thermal efficiency of engines. Different wall temperatures can affect the gas–liquid phase transition of the spray, and the temperature gradient from the ambient to the wall will cause a different mixture process in
[...] Read more.
Spray wall-impingement has large effects on the pollutant emissions and thermal efficiency of engines. Different wall temperatures can affect the gas–liquid phase transition of the spray, and the temperature gradient from the ambient to the wall will cause a different mixture process in the region nearby the wall. However, there are few studies on spray wall-impingement with different wall temperatures, particularly on the liquid–gas phase transition of the spray. Therefore, in this paper, the effects of different wall temperatures on spray-impingement have been investigated in a high-temperature, high-pressure constant volume combustion vessel. Cooling equipment was used to adjust the temperature difference between the wall and the ambient gas. n-Dodecane was chosen as the diesel surrogate to study the spray process. The spray wall-impingement was tested by changing the injection pressures (Pi) and wall temperatures (Tw). The ambient temperature (Ta) and ambient pressure (Pa) were kept constant at 773 K and 4 MPa, and the distance (L) between wall and injector was set to 35 mm to mimic the radius of the combustion chamber in heavy-duty diesel engines. A laser-induced exciplex fluorescence (LIEF) technique was used to probe the vapor and liquid phases of the injected fuel. Results show that the liquid phases of the spray do not reach the wall except in the condition of low wall temperature and high injection pressure. The liquid penetration develops and then becomes constant after 1 ms from the start of injection. With the increase of injection pressures (600–1600 bar), the liquid concentration of the spray decreases; however the liquid penetration decreases insignificantly. The wall temperature and the injection pressure have little influence on the liquid interpenetration process. For the vapor phase of the spray, the high concentration regions (equivalence ratio (φ) > 1) mainly distribute in the area of 10 mm away from the impact point on the wall. With the decrease of wall temperatures, the high-concentration regions are enlarged at the near wall regions. However, at the injection pressure of 1600 bar, the influence of wall temperatures on the equivalence ratio is small. The decreasing wall temperature deteriorates the mixing process of the fuel and ambient gas, but the effect is weakened with the increase of injection pressure. Full article
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Open AccessArticle Simulation Modeling and Optimization of Uniflow Scavenging System Parameters on Opposed-Piston Two-Stroke Engines
Energies 2018, 11(4), 940; https://doi.org/10.3390/en11040940
Received: 31 January 2018 / Revised: 9 April 2018 / Accepted: 10 April 2018 / Published: 16 April 2018
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Abstract
Based on the introduction of opposed-piston two-stroke (OP2S) gasoline direct injection (GDI) engines, the OP2S-GDI engine working principle and scavenging process were analyzed. GT-Power software was employed to model the working process based on the structural style and principle of OP2S-GDI engine. The
[...] Read more.
Based on the introduction of opposed-piston two-stroke (OP2S) gasoline direct injection (GDI) engines, the OP2S-GDI engine working principle and scavenging process were analyzed. GT-Power software was employed to model the working process based on the structural style and principle of OP2S-GDI engine. The tracer gas method and OP2S-GDI engine experiment were employed for model validation at full load of 6000 rpm. The OP2S-GDI engine scavenging system parameters were optimized, including intake port height stroke ratio, intake port circumference ratio, exhaust port height stroke ratio, exhaust port circumference ratio, and opposed-piston motion phase difference. At the same time, the effect of the port height stroke ratio and opposed-piston motion phase difference on effective compression ratio and expansion ratio were considered, and the indicated work was employed as the optimization objective. A three-level orthogonal experiment was applied in the calculation process to reduce the calculation work. The influence and correlation coefficient on the scavenging efficiency and delivery ratio were investigated by the orthogonal experiment analysis of intake and exhaust port height stroke ratio and circular utilization. The effect of the scavenging system parameters on delivery ratio, scavenging efficiency and indicated work were calculated to obtain the best parameters. The results show that intake port height stroke ratio is the main factor for the delivery ratio, while exhaust port height stroke ratio is the main factor to engine delivery ratio and scavenging efficiency. Full article
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Open AccessFeature PaperArticle Wire Mesh Dampers for Semi-Floating Ring Bearings in Automotive Turbochargers: Measurements of Structural Stiffness and Damping Parameters
Energies 2018, 11(4), 812; https://doi.org/10.3390/en11040812
Received: 28 February 2018 / Revised: 28 March 2018 / Accepted: 29 March 2018 / Published: 1 April 2018
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Abstract
The current work introduces a new semi-floating ring bearing (SFRB) system developed for improving the rotordynamic and vibration performance of automotive turbochargers (TCs) at extreme operation conditions, such as high temperature, severe external force excitation, and large rotor imbalance. The new bearing design
[...] Read more.
The current work introduces a new semi-floating ring bearing (SFRB) system developed for improving the rotordynamic and vibration performance of automotive turbochargers (TCs) at extreme operation conditions, such as high temperature, severe external force excitation, and large rotor imbalance. The new bearing design replaces outer oil films, i.e., squeeze film dampers (SFDs), in TC SFRBs with wire mesh dampers (WMDs). This SFRB configuration integrating WMDs aims to implement reliable mechanical components, as an inexpensive and simple alternative to SFDs, with consistent and superior damping capability, as well as predictable forced performance. Since WMDs are in series with the inner oil films of SFRBs, experimentally determined force coefficients of WMDs are of great importance in the design process of TC rotor-bearing systems (RBSs). Presently, the measurements of applied static load and ensuing deflection determine the structural stiffnesses of the WMDs. The WMD damping parameters, including dissipated energy, loss factor, and dry friction coefficient, are estimated from the area of the distinctive local hysteresis loop of the load versus WMD displacement data recorded during consecutive loading-unloading cycles as a function of applied preload with a constant amplitude of motion. The changes in WMD loss factor and dry friction coefficient due to increases in preload are more significant for the WMDs with lower density. The present work shows, to date, the most comprehensive measurements of static load characteristics on the WMDs for application into small automotive TCs. More importantly, the extensive test measurements of WMD deflection versus increasing static loads will aid to anchor predictions of future computation model. Full article
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Open AccessArticle A Two-Zone Combustion Model for Knocking Prediction of Marine Natural Gas SI Engines
Energies 2018, 11(3), 561; https://doi.org/10.3390/en11030561
Received: 19 January 2018 / Revised: 1 March 2018 / Accepted: 2 March 2018 / Published: 6 March 2018
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Abstract
The further thermal efficiency improvement of marine natural gas engine is constrained by a knocking phenomenon that commonly occurs in gas-fueled spark-ignited engines. It plays an important role to investigate how the knocking occurs and how to predict it based on the engine
[...] Read more.
The further thermal efficiency improvement of marine natural gas engine is constrained by a knocking phenomenon that commonly occurs in gas-fueled spark-ignited engines. It plays an important role to investigate how the knocking occurs and how to predict it based on the engine simulation model. In this paper, a two-zone model is developed to provide the prediction of knocking performance and NO emission, which is verified by engine test bed data from a transformed marine natural gas spark ignition (SI) engine. Cylindrical division theory is used to describe the shape of the two zones to decrease the computational cost, as well as a basic mechanism for NO concentration calculation. In order to solve the volume balance, three boundary parameters are introduced to determine the initial condition and mass flow between the two zones. Furthermore, boundary parameters’ variation and knocking factor (compression ratio and advanced ignition angle) will be discussed under different working conditions. Result shows that the two-zone model has sufficient accuracy in predicting engine performance, NO emission and knocking performance. Both the increasing compression ratio and advanced ignition angle have a promoting effect on knocking probability, knocking timing and knocking intensity. The knocking phenomenon can be avoided in the targeted natural gas SI engine by constraining the compression ratio smaller than 14 and advanced ignition angle later than 30° before top dead center (BTDC). Full article
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Open AccessArticle Investigation on the Potential of High Efficiency for Internal Combustion Engines
Energies 2018, 11(3), 513; https://doi.org/10.3390/en11030513
Received: 23 January 2018 / Revised: 20 February 2018 / Accepted: 24 February 2018 / Published: 27 February 2018
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Abstract
The current brake thermal efficiency of advanced internal combustion engines is limited to 50%, and how to further improve the efficiency is a challenge. In this study, a theoretical investigation on engine thermal efficiency was carried out using one-dimension simulations based on the
[...] Read more.
The current brake thermal efficiency of advanced internal combustion engines is limited to 50%, and how to further improve the efficiency is a challenge. In this study, a theoretical investigation on engine thermal efficiency was carried out using one-dimension simulations based on the first law of thermodynamics. The energy balance was evaluated by varying parameters such as compression ratio (CR); heat transfer coefficient; intake charge properties; and combustion phasing etc.—their influences on the efficiency limits were demonstrated. Results show that for a given heat transfer coefficient, an optimal CR exists to obtain the peak efficiency. The optimal CR decreases with the increase of heat transfer coefficient, and high CR with a low heat-transfer coefficient can achieve a significantly high efficiency. A higher density and specific heat ratio of intake charge, as well as a shorter combustion duration with a proper CA50 (crank angle at 50% of total heat release), can increase efficiency significantly. Methanol shows an excellent ability in decreasing the peak in-cylinder temperature; and the peak indicated efficiency is relatively higher than other tested fuels. The displacement has few effects on the indicated efficiency, while it shows a strong effect on the energy distribution between heat transfer and exhaust energy. All these strategies with high CR result in high in-cylinder pressure and temperature; which means a breakthrough of material is needed in the future. Full article
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Open AccessArticle Estimation of the Diesel Particulate Filter Soot Load Based on an Equivalent Circuit Model
Energies 2018, 11(2), 472; https://doi.org/10.3390/en11020472
Received: 31 January 2018 / Revised: 16 February 2018 / Accepted: 21 February 2018 / Published: 23 February 2018
Cited by 2 | PDF Full-text (1967 KB) | HTML Full-text | XML Full-text
Abstract
In order to estimate the diesel particulate filter (DPF) soot load and improve the accuracy of regeneration timing, a novel method based on an equivalent circuit model is proposed based on the electric-fluid analogy. This proposed method can reduce the impact of the
[...] Read more.
In order to estimate the diesel particulate filter (DPF) soot load and improve the accuracy of regeneration timing, a novel method based on an equivalent circuit model is proposed based on the electric-fluid analogy. This proposed method can reduce the impact of the engine transient operation on the soot load, accurately calculate the flow resistance, and improve the estimation accuracy of the soot load. Firstly, the least square method is used to identify the flow resistance based on the World Harmonized Transient Cycle (WHTC) test data, and the relationship between flow resistance, exhaust temperature and soot load is established. Secondly, the online estimation of the soot load is achieved by using the dual extended Kalman filter (DEKF). The results show that this method has good convergence and robustness with the maximal absolute error of 0.2 g/L at regeneration timing, which can meet engineering requirements. Additionally, this method can estimate the soot load under engine transient operating conditions and avoids a large number of experimental tests, extensive calibration and the analysis of complex chemical reactions required in traditional methods. Full article
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Open AccessFeature PaperArticle Analysis of the Effect of Vehicle, Driving and Road Parameters on the Transient Performance and Emissions of a Turbocharged Truck
Energies 2018, 11(2), 295; https://doi.org/10.3390/en11020295
Received: 8 January 2018 / Revised: 18 January 2018 / Accepted: 23 January 2018 / Published: 27 January 2018
Cited by 1 | PDF Full-text (9564 KB) | HTML Full-text | XML Full-text
Abstract
In this paper, a fundamental analysis of the effects of various influential parameters on the performance and emissions of a turbocharged truck operating under transient conditions is presented. The results derive from a detailed vehicle model that comprises two parts. The first is
[...] Read more.
In this paper, a fundamental analysis of the effects of various influential parameters on the performance and emissions of a turbocharged truck operating under transient conditions is presented. The results derive from a detailed vehicle model that comprises two parts. The first is an engine performance and emissions module that follows a mapping approach, with experimentally derived correction coefficients employed to account for transient discrepancies; this is then coupled to a comprehensive vehicle model that takes into account various vehicle operation attributes such as gearbox, tires, tire slip, etc. Soot, as well as nitrogen monoxide, are the examined engine-out pollutants, together with fuel consumption and carbon dioxide. The parameters examined are vehicular (mass and gearbox), driving (driver ‘aggressiveness’ and gear-shift profile) and road (type and grade). From the range of values investigated, the most critical parameters for the emission of NO and soot are vehicle mass, driving ‘aggressiveness’ and the exact gear-change profile. Vehicle mass, driving ‘aggressiveness’ and road-grade were identified as the most influential parameters for the emission of CO2. A notable statistical correlation was established between pollutant emissions (NO, soot) and vehicle mass or road-tire friction, as well as between fueling/CO2 and vehicle mass, road-tire friction and road grade. It is believed that the results obtained shed light into the effect of critical operating parameters on the engine-out emissions of a truck/bus, underlining at the same time the peculiarities of transient operating conditions. Full article
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Open AccessArticle Design and Performance Evaluation of an Axial Inflow Turbocharger Turbine
Energies 2018, 11(2), 278; https://doi.org/10.3390/en11020278
Received: 22 December 2017 / Revised: 18 January 2018 / Accepted: 19 January 2018 / Published: 24 January 2018
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Abstract
This paper is focussed on the development of an axial inflow turbocharger turbine as a viable alternative to a baseline radial turbine for certain applications. Additionally a variable geometry turbine (VGT) technology is incorporated into the axial-inflow turbine to additionally benefit both efficiency
[...] Read more.
This paper is focussed on the development of an axial inflow turbocharger turbine as a viable alternative to a baseline radial turbine for certain applications. Additionally a variable geometry turbine (VGT) technology is incorporated into the axial-inflow turbine to additionally benefit both efficiency and performance. The developed turbine was compared to the baseline in terms of engine performance, fuel consumption and emissions. The design and optimisation of the inlet casing, stator and rotor blades for axial inflow turbine were developed through CFD simulation. Then a VGT system was further developed, equipped with pivoting stator blades. Necessary data at various flow conditions were collected for engine modelling to test the engine performance achieved by the integration of the axial turbine, which achieved a maximum 86.2% isentropic efficiency at 102,000 rpm. The paper further focussed on the design and optimization of a volute for axial inflow turbine. Various initial designs were tested using CFD simulations and the chosen configuration was optimised further to improve overall stage efficiency, which reached 81.2%. Engine model simulations demonstrated that engine power and torque are significantly increased through the application of the proposed variable geometry axial turbocharger turbine. Full article
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Open AccessArticle Investigation of Sectional-Stage Loading Strategies on a Two-Stage Turbocharged Heavy-Duty Diesel Engine under Transient Operation with EGR
Energies 2018, 11(1), 69; https://doi.org/10.3390/en11010069
Received: 7 December 2017 / Revised: 26 December 2017 / Accepted: 26 December 2017 / Published: 1 January 2018
Cited by 1 | PDF Full-text (7256 KB) | HTML Full-text | XML Full-text
Abstract
The influence of loading strategies on combustion and emissions parameters is experimentally and numerically studied under typical 5 s transient conditions of constant speed and increasing torque. The experiment is conducted on a two-stage turbocharged heavy-duty diesel engine with a constant opening valve
[...] Read more.
The influence of loading strategies on combustion and emissions parameters is experimentally and numerically studied under typical 5 s transient conditions of constant speed and increasing torque. The experiment is conducted on a two-stage turbocharged heavy-duty diesel engine with a constant opening valve high-pressure exhaust gas recirculation (EGR) system. The test results show that: compared with the full-stage loading (FSL) strategy (constant loading rate during the entire transient process), the sectional-stage loading (SSL) strategies (holding a certain time at 50% load) can significantly reduce soot emissions (by 41.3%); the greater the first-stage loading rate, the better the torque response performance, which maximally increases by 56.7%. Besides, longer loading holding time can effectively restrain the overshoot of EGR rate and advance the combustion phase (CA10, CA50) at medium and large loads. However, the larger second-stage loading rate slightly deteriorates the combustion and emission performance. This deterioration situation can be markedly suppressed by adopting a suitable loading hold time. Full article
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Review

Jump to: Research

Open AccessReview A Review of Particulate Number (PN) Emissions from Gasoline Direct Injection (GDI) Engines and Their Control Techniques
Energies 2018, 11(6), 1417; https://doi.org/10.3390/en11061417
Received: 25 April 2018 / Revised: 22 May 2018 / Accepted: 25 May 2018 / Published: 1 June 2018
Cited by 4 | PDF Full-text (7562 KB) | HTML Full-text | XML Full-text
Abstract
Particulate Matter (PM) emissions from gasoline direct injection (GDI) engines, particularly Particle Number (PN) emissions, have been studied intensively in both academia and industry because of the adverse effects of ultrafine PM emissions on human health and other environmental concerns. GDI engines are
[...] Read more.
Particulate Matter (PM) emissions from gasoline direct injection (GDI) engines, particularly Particle Number (PN) emissions, have been studied intensively in both academia and industry because of the adverse effects of ultrafine PM emissions on human health and other environmental concerns. GDI engines are known to emit a higher number of PN emissions (on an engine-out basis) than Port Fuel Injection (PFI) engines, due to the reduced mixture homogeneity in GDI engines. Euro 6 emission standards have been introduced in Europe (and similarly in China) to limit PN emissions from GDI engines. This article summarises the current state of research in GDI PN emissions (engine-out) including a discussion of PN formation, and the characteristics of PN emissions from GDI engines. The effect of key GDI engine operating parameters is analysed, including air-fuel ratio, ignition and injection timing, injection pressure, and EGR; in addition the effect of fuel composition on particulate emissions is explored, including the effect of oxygenate components such as ethanol. Full article
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