Energies

Research

21 pages, 8550 KiB

Open AccessArticle

Development and Assessment of an Integrated 1D-3D CFD Codes Coupling Methodology for Diesel Engine Combustion Simulation and Optimization

by Federico Millo, Andrea Piano, Benedetta Peiretti Paradisi, Mario Rocco Marzano, Andrea Bianco and Francesco C. Pesce

Energies 2020, 13(7), 1612; https://doi.org/10.3390/en13071612 - 1 Apr 2020

Cited by 16 | Viewed by 5182

Abstract

In this paper, an integrated and automated methodology for the coupling between 1D- and 3D-CFD simulation codes is presented, which has been developed to support the design and calibration of new diesel engines. The aim of the proposed methodology is to couple 1D [...] Read more.

In this paper, an integrated and automated methodology for the coupling between 1D- and 3D-CFD simulation codes is presented, which has been developed to support the design and calibration of new diesel engines. The aim of the proposed methodology is to couple 1D engine models, which may be available in the early stage engine development phases, with 3D predictive combustion simulations, in order to obtain reliable estimates of engine performance and emissions for newly designed automotive diesel engines. The coupling procedure features simulations performed in 1D-CFD by means of GT-SUITE and in 3D-CFD by means of Converge, executed within a specifically designed calculation methodology. An assessment of the coupling procedure has been performed by comparing its results with experimental data acquired on an automotive diesel engine, considering different working points, including both part load and full load conditions. Different multiple injection schedules have been evaluated for part-load operation, including pre and post injections. The proposed methodology, featuring detailed 3D chemistry modeling, was proven to be capable assessing pollutant formation properly, specifically to estimate NOx concentrations. Soot formation trends were also well-matched for most of the explored working points. The proposed procedure can therefore be considered as a suitable methodology to support the design and calibration of new diesel engines, due to its ability to provide reliable engine performance and emissions estimations from the early stage of a new engine development. Full article

(This article belongs to the Special Issue Internal Combustion Engines Improving Performance, Fuel Economy and Emissions)

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19 pages, 7654 KiB

Open AccessArticle

Implementation and Assessment of a Model-Based Controller of Torque and Nitrogen Oxide Emissions in an 11 L Heavy-Duty Diesel Engine

by Fabio Cococcetta, Roberto Finesso, Gilles Hardy, Omar Marello and Ezio Spessa

Energies 2019, 12(24), 4704; https://doi.org/10.3390/en12244704 - 10 Dec 2019

Cited by 9 | Viewed by 2522

Abstract

A previously developed model-based controller of torque and nitrogen oxides emissions has been implemented and assessed on a heavy-duty 11 L FPT prototype Cursor 11 diesel engine. The implementation has been realized by means of a rapid prototyping device, which has allowed the [...] Read more.

A previously developed model-based controller of torque and nitrogen oxides emissions has been implemented and assessed on a heavy-duty 11 L FPT prototype Cursor 11 diesel engine. The implementation has been realized by means of a rapid prototyping device, which has allowed the standard functions of the engine control unit to be by-passed. The activity was carried out within the IMPERIUM H2020 EU Project, which is aimed at reducing the consumption of fuel and urea in heavy-duty trucks up to 20%, while maintaining the compliance with the legal emission limits. In particular, the developed controller is able to achieve desired targets of brake mean effective pressure (BMEP) (or brake torque) and engine-out nitrogen oxides emissions. To this aim, the controller adjusts the fuel quantity and the start of injection of the main pulse in real-time. The controller is based on a previously developed low-throughput combustion model, which estimates the heat release rate, the in-cylinder pressure, the BMEP (or torque) and the engine-out nitrogen oxide emissions. The controller has been assessed at both steady-state and transient operations, through rapid prototyping tests at the engine test bench and on the road. Full article

(This article belongs to the Special Issue Internal Combustion Engines Improving Performance, Fuel Economy and Emissions)

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23 pages, 5575 KiB

Open AccessArticle

A Control-Oriented Engine Torque Online Estimation Approach for Gasoline Engines Based on In-Cycle Crankshaft Speed Dynamics

by Qiang Tong, Hui Xie, Kang Song and Dong Zou

Energies 2019, 12(24), 4683; https://doi.org/10.3390/en12244683 - 9 Dec 2019

Cited by 3 | Viewed by 3160

Abstract

Engine brake torque is a key feedback variable for the optimal torque split control of an engine–motor hybrid powertrain system. Due to the limitations in available sensors, however, engine torque is difficult to measure directly. For torque estimation, the unknown external load torque [...] Read more.

Engine brake torque is a key feedback variable for the optimal torque split control of an engine–motor hybrid powertrain system. Due to the limitations in available sensors, however, engine torque is difficult to measure directly. For torque estimation, the unknown external load torque and the overlap of the expansion stroke between cylinders introduce a great disturbance to engine speed dynamics. This makes the conventional cycle average engine speed-based estimation approach unusable. In this article, an in-cycle crankshaft speed-based indicated torque estimation approach is proposed for a four-cylinder engine. First, a unique crankshaft angle window is selected for load torque estimation without the influence of combustion torque. Then, an in-cycle angle-domain crankshaft speed dynamic model is developed for engine indicated torque estimation. To account for the effects of model inaccuracy and unknown external disturbances, a “total disturbance” term is introduced. The total disturbance is then estimated by an adaptive observer using the engine’s historical operating data. Finally, a real-time correction method for the friction torque is proposed in the fuel cut-off scenario. Combining the aforementioned torque estimators, the brake torque can be obtained. The proposed algorithm is implemented in an in-house developed multi-core engine control unit (ECU). Experimental validation results on an engine test bench show that the algorithm’s execution time is about 3.2 ms, and the estimation error of the brake torque is within 5%. Therefore, the proposed method is a promising way to accurately estimate engine torque in real-time. Full article

(This article belongs to the Special Issue Internal Combustion Engines Improving Performance, Fuel Economy and Emissions)

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19 pages, 2729 KiB

Open AccessArticle

Investigation on an Injection Strategy Optimization for Diesel Engines Using a One-Dimensional Spray Model

by Intarat Naruemon, Long Liu, Qihao Mei and Xiuzhen Ma

Energies 2019, 12(21), 4221; https://doi.org/10.3390/en12214221 - 5 Nov 2019

Cited by 6 | Viewed by 2778

Abstract

Common rail systems have been widely used in diesel engines due to the stricter emission regulations. The advances in injector technology and ultrahigh injection pressure greatly promote the development of multiple-injection strategy, leading to the shorter injection duration and more variable injection rate [...] Read more.

Common rail systems have been widely used in diesel engines due to the stricter emission regulations. The advances in injector technology and ultrahigh injection pressure greatly promote the development of multiple-injection strategy, leading to the shorter injection duration and more variable injection rate shape, which makes the mixing process more significant for the formation of pollutant emission. In order to study the mixing process of diesel sprays under variable injection rate shapes and find the optimized injection strategy, a one-dimensional spray model was modified in this paper. The model was validated by the measured spray penetrations based on shadowgraphy experiments with the varying injection rate. The simulations were performed with five injection rate shapes, triangle, ramping-up, ramping-down, rectangle and trapezoid. Their spray penetrations, entrainment rates and equivalence ratios along spray axial distance are compared. The potentials of multiple-injection and gas-jet after end-of-injection (EOI) to improve mixing process and emission reduction are discussed finally. The results indicated that ramping-up injection rate obtains the highest entrainment rate after EOI, and it needs 1.5 times of injection duration for the entrainment wave to arrive at the spray tip. For the other four injection rates, the sprays can be treated as a steady-like state, needing twice of injection duration from EOI to the time the entrainment wave reaches the spray tip. The multiple-injection with proper injection rate shape enhanced the entrainment rate, and the gas-jet after EOI affected the mixture distribution and entrainment rate in spray tail under ramping-down injection rate. Full article

(This article belongs to the Special Issue Internal Combustion Engines Improving Performance, Fuel Economy and Emissions)

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16 pages, 3313 KiB

Open AccessArticle

Comparison of the Emissions, Noise, and Fuel Consumption Comparison of Direct and Indirect Piezoelectric and Solenoid Injectors in a Low-Compression-Ratio Diesel Engine

by Stefano d’Ambrosio, Alessandro Ferrari, Alessandro Mancarella, Salvatore Mancò and Antonio Mittica

Energies 2019, 12(21), 4023; https://doi.org/10.3390/en12214023 - 23 Oct 2019

Cited by 11 | Viewed by 4678

Abstract

An experimental investigation has been carried out to compare the performance and emissions of a low-compression-ratio Euro 5 diesel engine featuring high EGR rates, equipped with different injector technologies, i.e., solenoid, indirect-acting, and direct-acting piezoelectric. The comparisons, performed with reference to a state-of-the-art [...] Read more.

An experimental investigation has been carried out to compare the performance and emissions of a low-compression-ratio Euro 5 diesel engine featuring high EGR rates, equipped with different injector technologies, i.e., solenoid, indirect-acting, and direct-acting piezoelectric. The comparisons, performed with reference to a state-of-the-art double fuel injection calibration, i.e., pilot-Main (pM), are presented in terms of engine-out exhaust emissions, combustion noise (CN), and fuel consumption, at low–medium engine speeds and loads. The differences in engine performance and emissions of the solenoidal, indirect-acting, and direct-acting piezoelectric injector setups have been found on the basis of experimental results to mainly depend on the specific features of their hydraulic circuits rather than on the considered injector driving system. Full article

(This article belongs to the Special Issue Internal Combustion Engines Improving Performance, Fuel Economy and Emissions)

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18 pages, 8663 KiB

Open AccessArticle

Design of an Electromagnetic Variable Valve Train with a Magnetorheological Buffer

by He Guo, Liang Liu, Xiangbin Zhu, Siqin Chang and Zhaoping Xu

Energies 2019, 12(20), 3999; https://doi.org/10.3390/en12203999 - 21 Oct 2019

Cited by 8 | Viewed by 3614

Abstract

In this paper, an electromagnetic variable valve train with a magnetorheological buffer (EMVT with MR buffer) is proposed. This system is mainly composed of an electromagnetic linear actuator (EMLA) and a magnetorheological buffer (MR buffer). The valves of an internal combustion engine are [...] Read more.

In this paper, an electromagnetic variable valve train with a magnetorheological buffer (EMVT with MR buffer) is proposed. This system is mainly composed of an electromagnetic linear actuator (EMLA) and a magnetorheological buffer (MR buffer). The valves of an internal combustion engine are driven by the EMLA directly to open and close, which can adjust the valve lift and phase angle of the engine. At the same time, MR buffer can reduce the seat velocity of the valve and realize the seat buffer of the electromagnetic variable valve. In this paper, the overall design scheme of the system is proposed and the structure design, finite element simulation of the EMLA, and the MR buffer are carried out. The electromagnetic force characteristics of the EMLA and buffer force of the MR buffer are measured, and the seat buffering performance is verified as well. Experiments and simulation results show that the electromagnetic force of the EMLA can reach 320.3 N when the maximum coil current is 40 A. When the current of the buffer coil is 2.5 A and the piston’s motion frequency is 5 Hz, the buffering force can reach 35 N. At the same time, a soft landing can be realized when the valve is seated. Full article

(This article belongs to the Special Issue Internal Combustion Engines Improving Performance, Fuel Economy and Emissions)

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15 pages, 2999 KiB

Open AccessEditor’s ChoiceArticle

An Experimental Study on the Performance and Emission of the diesel/CNG Dual-Fuel Combustion Mode in a Stationary CI Engine

by Arkadiusz Jamrozik, Wojciech Tutak and Karol Grab-Rogaliński

Energies 2019, 12(20), 3857; https://doi.org/10.3390/en12203857 - 12 Oct 2019

Cited by 51 | Viewed by 9332

Abstract

One of the possibilities to reduce diesel fuel consumption and at the same time reduce the emission of diesel engines, is the use of alternative gaseous fuels, so far most commonly used to power spark ignition engines. The presented work concerns experimental research [...] Read more.

One of the possibilities to reduce diesel fuel consumption and at the same time reduce the emission of diesel engines, is the use of alternative gaseous fuels, so far most commonly used to power spark ignition engines. The presented work concerns experimental research of a dual-fuel compression-ignition (CI) engine in which diesel fuel was co-combusted with CNG (compressed natural gas). The energy share of CNG gas was varied from 0% to 95%. The study showed that increasing the share of CNG co-combusted with diesel in the CI engine increases the ignition delay of the combustible mixture and shortens the overall duration of combustion. For CNG gas shares from 0% to 45%, due to the intensification of the combustion process, it causes an increase in the maximum pressure in the cylinder, an increase in the rate of heat release and an increase in pressure rise rate. The most stable operation, similar to a conventional engine, was characterized by a diesel co-combustion engine with 30% and 45% shares of CNG gas. Increasing the CNG share from 0% to 90% increases the nitric oxide emissions of a dual-fuel engine. Compared to diesel fuel supply, co-combustion of this fuel with 30% and 45% CNG energy shares contributes to the reduction of hydrocarbon (HC) emissions, which increases after exceeding these values. Increasing the share of CNG gas co-combusted with diesel fuel, compared to the combustion of diesel fuel, reduces carbon dioxide emissions, and almost completely reduces carbon monoxide in the exhaust gas of a dual-fuel engine. Full article

(This article belongs to the Special Issue Internal Combustion Engines Improving Performance, Fuel Economy and Emissions)

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41 pages, 9182 KiB

Open AccessArticle

Comparison of Physics-Based, Semi-Empirical and Neural Network-Based Models for Model-Based Combustion Control in a 3.0 L Diesel Engine

by Song Hu, Stefano d’Ambrosio, Roberto Finesso, Andrea Manelli, Mario Rocco Marzano, Antonio Mittica, Loris Ventura, Hechun Wang and Yinyan Wang

Energies 2019, 12(18), 3423; https://doi.org/10.3390/en12183423 - 5 Sep 2019

Cited by 14 | Viewed by 3481

Abstract

A comparison of four different control-oriented models has been carried out in this paper for the simulation of the main combustion metrics in diesel engines, i.e., combustion phasing, peak firing pressure, and brake mean effective pressure. The aim of the investigation has been [...] Read more.

A comparison of four different control-oriented models has been carried out in this paper for the simulation of the main combustion metrics in diesel engines, i.e., combustion phasing, peak firing pressure, and brake mean effective pressure. The aim of the investigation has been to understand the potential of each approach in view of their implementation in the engine control unit (ECU) for onboard combustion control applications. The four developed control-oriented models, namely the baseline physics-based model, the artificial neural network (ANN) physics-based model, the semi-empirical model, and direct ANN model, have been assessed and compared under steady-state conditions and over the Worldwide Harmonized Heavy-duty Transient Cycle (WHTC) for a Euro VI FPT F1C 3.0 L diesel engine. Moreover, a new procedure has been introduced for the selection of the input parameters. The direct ANN model has shown the best accuracy in the estimation of the combustion metrics under both steady-state/transient operating conditions, since the root mean square errors are of the order of 0.25/1.1 deg, 0.85/9.6 bar, and 0.071/0.7 bar for combustion phasing, peak firing pressure, and brake mean effective pressure, respectively. Moreover, it requires the least computational time, that is, less than 50 μs when the model is run on a rapid prototyping device. Therefore, it can be considered the best candidate for model-based combustion control applications. Full article

(This article belongs to the Special Issue Internal Combustion Engines Improving Performance, Fuel Economy and Emissions)

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22 pages, 9008 KiB

Open AccessArticle

Impact of Electrically Assisted Turbocharger on the Intake Oxygen Concentration and Its Disturbance Rejection Control for a Heavy-duty Diesel Engine

by Chao Wu, Kang Song, Shaohua Li and Hui Xie

Energies 2019, 12(15), 3014; https://doi.org/10.3390/en12153014 - 5 Aug 2019

Cited by 7 | Viewed by 4313

Abstract

The electrically assisted turbocharger (EAT) shows promise in simultaneously improving the boost response and reducing the fuel consumption of engines with assist. In this paper, experimental results show that 7.8% fuel economy (FE) benefit and 52.1% improvement in transient boost response can be [...] Read more.

The electrically assisted turbocharger (EAT) shows promise in simultaneously improving the boost response and reducing the fuel consumption of engines with assist. In this paper, experimental results show that 7.8% fuel economy (FE) benefit and 52.1% improvement in transient boost response can be achieved with EAT assist. EAT also drives the need for a new feedback variable for the air system control, instead of the exhaust recirculation gas (EGR) rate that is widely used in conventional turbocharged engines (nominal system). Steady-state results show that EAT assist allows wider turbine vane open and reduces pre-turbine pressure, which in turn elevates the engine volumetric efficiency hence the engine air flow rate at fixed boost pressure. Increased engine air flow rate, together with the reduced fuel amount necessary to meet the torque demand with assist, leads to the increase of the oxygen concentration in the exhaust gas (EGR gas dilution). Additionally, transient results demonstrate that the enhanced air supply from the compressor and the diluted EGR gas result in a spike in the oxygen concentration in the intake manifold (X_oim) during tip-in, even though there is no spike in the EGR rate response profile. Consequently, there is Nitrogen Oxides (NOx) emission spike, although the response of boost pressure and EGR rate is smooth (no spike is seen). Therefore, in contrast to EGR rate, X_oim is found to be a better choice for the feedback variable. Additionally, a disturbance observer-based X_oim controller is developed to attenuate the disturbances from the turbine vane position variation. Simulation results on a high-fidelity GT-SUTIE model show over 43% improvement in disturbance rejection capability in terms of recovery time, relative to the conventional proportional-integral-differential (PID) controller. This X_oim-based disturbance rejection control solution is beneficial in the practical application of the EAT system. Full article

(This article belongs to the Special Issue Internal Combustion Engines Improving Performance, Fuel Economy and Emissions)

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21 pages, 4385 KiB

Open AccessArticle

Numerical Investigation of 48 V Electrification Potential in Terms of Fuel Economy and Vehicle Performance for a Lambda-1 Gasoline Passenger Car

by Federico Millo, Francesco Accurso, Alessandro Zanelli and Luciano Rolando

Energies 2019, 12(15), 2998; https://doi.org/10.3390/en12152998 - 3 Aug 2019

Cited by 12 | Viewed by 4085

Abstract

Real Driving Emissions (RDE) regulations require the adoption of stoichiometric operation across the entire engine map for downsized turbocharged gasoline engines, which have been so far generally exploiting spark timing retard and mixture enrichment for knock mitigation. However, stoichiometric operation has a detrimental [...] Read more.

Real Driving Emissions (RDE) regulations require the adoption of stoichiometric operation across the entire engine map for downsized turbocharged gasoline engines, which have been so far generally exploiting spark timing retard and mixture enrichment for knock mitigation. However, stoichiometric operation has a detrimental effect on engine and vehicle performances if no countermeasures are taken, such as alternative approaches for knock mitigation, as the exploitation of Miller cycle and/or powertrain electrification to improve vehicle acceleration performance. This research activity aims, therefore, to assess the potential of 48 V electrification and of the adoption of Miller cycle for a downsized and stoichiometric turbocharged gasoline engine. An integrated vehicle and powertrain model was developed for a reference passenger car, equipped with a EU5 gasoline turbocharged engine. Afterwards, two different 48 V electrified powertrain concepts, one featuring a Belt Starter Generator (BSG) mild-hybrid architecture, the other featuring, in addition to the BSG, a Miller cycle engine combined with an e-supercharger were developed and investigated. Vehicle performances were evaluated both in terms of elasticity maneuvers and of CO₂ emissions for type approval and RDE driving cycles. Numerical simulations highlighted potential improvements up to 16% CO₂ reduction on RDE driving cycle of a 48 V electrified vehicle featuring a high efficiency powertrain with respect to a EU5 engine and more than 10% of transient performance improvement. Full article

(This article belongs to the Special Issue Internal Combustion Engines Improving Performance, Fuel Economy and Emissions)

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25 pages, 5383 KiB

Open AccessArticle

Thermal Decomposition of a Single AdBlue^® Droplet Including Wall–Film Formation in Turbulent Cross-Flow in an SCR System

by Kaushal Nishad, Marcus Stein, Florian Ries, Viatcheslav Bykov, Ulrich Maas, Olaf Deutschmann, Johannes Janicka and Amsini Sadiki

Energies 2019, 12(13), 2600; https://doi.org/10.3390/en12132600 - 6 Jul 2019

Cited by 8 | Viewed by 4593

Abstract

The selective catalytic reduction (SCR) methodology is notably recognized as the widely applied strategy for NO_X control in exhaust after-treatment technologies. In real SCR systems, complex unsteady turbulent multi-phase flow phenomena including poly-dispersed AdBlue^® spray evolve with a wide ranging relative [...] Read more.

The selective catalytic reduction (SCR) methodology is notably recognized as the widely applied strategy for NO_X control in exhaust after-treatment technologies. In real SCR systems, complex unsteady turbulent multi-phase flow phenomena including poly-dispersed AdBlue^® spray evolve with a wide ranging relative velocity between the droplet phase and carrier gas phase. This results from an AdBlue^® spray that is injected into a mixing pipe which is cross-flowing by a hot exhaust gas. To reduce the complexity while gaining early information on the injected droplet size and velocity needed for a minimum deposition and optimal conversion, a single droplet with a specified diameter is addressed to mimic a spray featuring the same Sauter Mean Diameter. For that purpose, effects of turbulent hot cross-flow on thermal decomposition processes of a single AdBlue^® droplet are numerically investigated. Thereby, a single AdBlue^® droplet is injected into a hot cross-flowing stream within a mixing pipe in which it may experience phase change processes including interaction with the pipe wall along with liquid wall–film and possible solid deposit formation. First of all, the prediction capability of the multi-component evaporation model and thermal decomposition is evaluated against the detailed simulation results for standing droplet case for which experimental data is not available. Next, exploiting Large Eddy Simulation features the effect of hot turbulent co- and cross-flowing streams on the dynamic droplet characteristics and on the droplet/wall interaction is analyzed for various droplet diameters and operating conditions. This impact is highlighted in terms of droplet evaporation time, decomposition efficiency, droplet trajectories and wall–film formation. It turns out that smaller AdBlue^® droplet diameter, higher gas temperature and relative velocity lead to shorter droplet life time as the droplet evaporates faster. Under such conditions, possible droplet/wall interaction processes on the pipe wall or at the entrance front of the monolith may be avoided. Since the ammonia (NH₃) gas generated by urea decomposition is intended to reduce NO_X emission in the SCR system, it is apparent for the prediction of high NO_X removal performance that UWS injector system which allows to realize such operating conditions is favorable to support high conversion efficiency of urea into NH₃. Full article

(This article belongs to the Special Issue Internal Combustion Engines Improving Performance, Fuel Economy and Emissions)

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24 pages, 7549 KiB

Open AccessArticle

A New Physics-Based Modeling Approach for a 0D Turbulence Model to Reflect the Intake Port and Chamber Geometries and the Corresponding Flow Structures in High-Tumble Spark-Ignition Engines

by Yirop Kim, Myoungsoo Kim, Sechul Oh, Woojae Shin, Seokwon Cho and Han Ho Song

Energies 2019, 12(10), 1898; https://doi.org/10.3390/en12101898 - 18 May 2019

Cited by 5 | Viewed by 4667

Abstract

Turbulence is one of the most important aspects in spark-ignition engines as it can significantly affect burn rates, heat transfer rates, and combustion stability, and thus the performance. Turbulence originates from a large-scale mean motion that occurs during the induction process, which mainly [...] Read more.

Turbulence is one of the most important aspects in spark-ignition engines as it can significantly affect burn rates, heat transfer rates, and combustion stability, and thus the performance. Turbulence originates from a large-scale mean motion that occurs during the induction process, which mainly consists of tumble motion in modern spark-ignition engines with a pentroof cylinder head. Despite its significance, most 0D turbulence models rely on calibration factors when calculating the evolution of tumble motion and its conversion into turbulence. In this study, the 0D tumble model has been improved based on the physical phenomena, as an attempt to develop a comprehensive model that predicts flow dynamics inside the cylinder. The generation and decay rates of tumble motion are expressed with regards of the flow structure in a realistic combustion chamber geometry, while the effects of port geometry on both charging efficiency and tumble generation rate are reflected by supplementary steady CFD. The developed tumble model was integrated with the standard k-ε model, and the new turbulence model has been validated with engine experimental data for various changes in operating conditions including engine speed, load, valve timing, and engine geometry. The calculated results showed a reasonable correlation with the measured combustion duration, verifying this physics-based model can properly predict turbulence characteristics without any additional calibration process. This model can suggest greater insights on engine operation and is expected to assist the optimization process of engine design and operating strategies. Full article

(This article belongs to the Special Issue Internal Combustion Engines Improving Performance, Fuel Economy and Emissions)

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17 pages, 3864 KiB

Open AccessArticle

Comparative Analysis of the Combustion Stability of Diesel-Methanol and Diesel-Ethanol in a Dual Fuel Engine

by Arkadiusz Jamrozik, Wojciech Tutak, Renata Gnatowska and Łukasz Nowak

Energies 2019, 12(6), 971; https://doi.org/10.3390/en12060971 - 13 Mar 2019

Cited by 43 | Viewed by 5932

Abstract

The co-combustion of diesel with alcohol fuels in a compression ignition dual fuel engine is one of the ways of using alternative fuels to power combustion engines. Scientific explorations in this respect should not only concern the combustion process in one engine cycle, [...] Read more.

The co-combustion of diesel with alcohol fuels in a compression ignition dual fuel engine is one of the ways of using alternative fuels to power combustion engines. Scientific explorations in this respect should not only concern the combustion process in one engine cycle, which is most often not representative for a longer engine life, but should also include an analysis of multiple cycles, which would allow for indicating reliable parameters of engine operation and its stability. This paper presents experimental examinations of a CI engine with a dual fuel system, in which co-combustion was performed for diesel and two alcohol fuels (methanol and ethanol) with energy contents of 20%, 30%, 40% and 50%. The research included the analysis of the combustion process and the analysis of cycle-by-cycle variation of the 200 subsequent engine operation cycles. It was shown that the presence and increase in the share of methanol and ethanol used for co-combustion with diesel fuel causes an increase in ignition delay and increases the heat release rate and maximum combustion pressure values. A larger ignition delay is observed for co-combustion with methanol. Based on changes in the coefficient of variation of the indicated mean effective pressure (COV_IMEP) and the function of probability density of the indicated mean effective pressure (f(IMEP)), prepared for a series of engine operation cycles, it can be stated that the increase in the percentage of alcohol fuel used for co-combustion with diesel fuel does not impair combustion stability. For the highest percentage of alcohol fuel (50%), the co-combustion of diesel with methanol shows a better stability. Full article

(This article belongs to the Special Issue Internal Combustion Engines Improving Performance, Fuel Economy and Emissions)

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21 pages, 13998 KiB

Open AccessArticle

Combustion Analysis of Homogeneous Charge Compression Ignition in a Motorcycle Engine Using a Dual-Fuel with Exhaust Gas Recirculation

by Yuh-Yih Wu and Ching-Tzan Jang

Energies 2019, 12(5), 847; https://doi.org/10.3390/en12050847 - 4 Mar 2019

Cited by 6 | Viewed by 4409

Abstract

Exhaust emissions from the large population of motorcycles are a major issue in Asian countries. The regulation of exhaust emissions is therefore becoming increasingly stringent, with those relating to nitrogen oxides (NO_x) the most difficult to pass. The homogeneous charge compression [...] Read more.

Exhaust emissions from the large population of motorcycles are a major issue in Asian countries. The regulation of exhaust emissions is therefore becoming increasingly stringent, with those relating to nitrogen oxides (NO_x) the most difficult to pass. The homogeneous charge compression ignition (HCCI) has special combustion characteristics and hence produces low NO_x emissions and exhibits high thermal efficiency. This study developed an HCCI system for a 150 cc motorcycle engine. The target engine was modified using a dual-fuel of dimethyl ether (DME) and gasoline with exhaust gas recirculation (EGR). It was tested at 2000–4000 rpm and the analysis was focused on 2000 rpm. The DME was supplied continuously at an injection pressure of 1.5 kg/cm². The gasoline injection rate was adjusted at a pressure of 2.5 kg/cm². A brake-specific fuel consumption of <250 g/kW·h was achieved under a condition of air–fuel equivalence ratio (λ) < 2 and an EGR of 25%. The nitric oxide concentration was too low to measure. The brake mean effective pressure (BMEP) increased by 65.8% from 2.93 to 4.86 bar when the EGR was 0% to 25%. The combustion efficiency was close to 100% when the BMEP was >3 bar. Full article

(This article belongs to the Special Issue Internal Combustion Engines Improving Performance, Fuel Economy and Emissions)

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