Crank Angle Degrees Research Articles

Parametric investigation of particulate matter emissions in a gasoline direct injection engine using computational fluid dynamics modelling

ABSTRACT The effects of start of injection (SOI) timing, spark ignition (SI) timing and exhaust gas recirculation (EGR) rate on particulate matter (PM) emissions in a gasoline direct injection engine are examined through computational fluid dynamics modelling. Varying SOI timing entails compromising between longer mixing time and lower fuel impingement. Delaying the optimal SOI timing by 20 crank angle degree (CAD) results in a 78% increase in number density and a threefold-increase in mass density. PM control benefits from retarding SI timing which prolongs mixing time and shortens soot residence time. A 10 CAD delay from the SI timing at 25 CAD before top dead centre reduces number density and mass density by 65% and 57%, respectively. EGR renders the in-cylinder condition unfavourable for PM formation despite the overall increase in equivalence ratio. For 10% EGR rate, a drop of 547 K in peak temperature decreases number density by 24%. However, mass density increases by a 1.7 factor due to high particle growth species availability.

Numerical Investigation of Equivalence Ratio Effects on a Converted Diesel Engine Using Natural Gas

Abstract In this study, a diesel tractor engine is numerically modeled to run entirely on natural gas by installing a natural gas fuel injector on the intake manifold and assembling a spark plug in lieu of a diesel injector. In the numerical study, the methane chemical kinetic mechanism representing natural gas, Reynolds-averaged Navier–Stokes (RANS) k–e turbulence, and the G-equation combustion model were used. The spark-ignition time was assumed to be 719.5 crank angle degree (CAD), which was the start of the diesel injection time. Analysis was carried out at 2300 revolutions per minute (rpm), at a high compression ratio of 17.5:1, at a fixed spark-ignition time, and at eight different equivalence ratios under full load. The equivalence ratio was changed by keeping the air mass constant and reducing the mass of the fuel. The effects of the obtained equivalence ratio on engine performance, combustion characteristics, and emission values were investigated. The results revealed that natural gas could be used up to Φ = 0.60 without affecting performance, increasing emissions, or exceeding the knock limit compared with the diesel cycle. In addition, it was observed that ultralow (below 10 particulate per million (ppm)) emission values could be obtained by further reducing the equivalence ratio, providing a uniform thermal field.

Exploring the effects of pilot injection timing and natural gas flow rates on the performance of twin-cylinder compression ignition engine

ABSTRACT Alternative fuels offer various advantages over traditional fossil fuels, including the fact that they are recyclable, sustainable, Contribute to energy independence, and reduce emissions. Renewable fuels such as Compressed natural gas and biodiesel were used in this study. Natural gas is an appealing and appealing fuel because of its vast availability, low Cost, and Clean-burning qualities. The use of biodiesel, namely mustard oil biodiesel, aids in making it Cleaner and more Cost-effective. The present study aims to reduce tailpipe emissions from diesel engines using dual-fuel Combustion, which employs a Combination of fossil and renewable fuels. An experimental analysis was Carried out to evaluate the effectiveness and tailpipe emissions of a twin-cylinder diesel engine fueled by pilot Mustard oil biodiesel (MOB) and CNG, with variations in the rate of CNG flow and time of pilot injection. According to the findings, advanced pilot injection timing (PIT) at 24°CA bTDC (degree Crank angle before top dead Center) and using a lower rate of CNG flow (0.2 kg/h) resulted in the highest brake thermal efficiency (31.21%), while brake specific fuel Consumption decreased by nearly 10% at this setting. Increasing pilot fuel injection to 24°CA bTDC and maintaining a modest rate of CNG flow at 0.2 kg/h in a dual-fuel model decreased NOx emissions by 26% when Compared to diesel alone mode, but resulted in a minor rise in CO emissions. The Current study may aid in the Conversion of a significant number of small to mid-segment diesel engines used in irrigation and the industrial sector in the Indian subcontinent. The study helps in minimizing NOx emissions while also lowering import fossil fuel Costs.

A Double-Wiebe Function for Reactivity Controlled Compression Ignition Combustion Using Reformate Diesel

AbstractReactivity controlled compression ignition (RCCI) combustion has previously been proposed as a method to achieve high fuel conversion efficiency and reduce engine emissions. A single-fuel RCCI combustion strategy can have decreased fuel system complexity by using a reformate fuel for port fuel injection and the parent fuel (diesel) for direct injection. This paper presents a one-dimensional computational model of a compression ignition engine with single-fuel RCCI. A Wiebe function is used to predict the combustion process by representing the mass fraction burned (MFB) on a crank angle resolved basis. One single-Wiebe function (SWF) and two double-Wiebe functions(DWFs) were fitted to experimentally derive MFB data using the least-square method. The fitted results were compared with MFBs calculated from experimental data to verify the accuracy. The SWF did not fully capture the MFB curve with high fidelity while the detailed DWF captured the MFB curve within a root mean square error of 1.4%. The reduced double-Wiebe function (RDWF) also resulted in a predicted combustion profile with similar accuracy. Hence, the RDWF was used in a GT-power thermodynamic study to understand the effects of the low-temperature heat release (LTHR) fraction and combustion phasing on combustion characteristics. At optimum phasing of 5–10 crank angle degree after the top dead center, increasing the LTHR fraction from 20% to 60% resulted in the fuel conversion efficiency increasing from 39.5% to 41.1%, thus suggesting that the reformate fuel-based RCCI strategy is viable to unlock improved combustion performance.

Multidimensional Computational Fluid Dynamics Combustion Process Modeling of a 6V150 Diesel Engine

Abstract The smart diesel program requires the engine electronic control unit to consider additional parameters, such as altitude and climatic conditions, in the mapping calibration process. A specially designed environmental simulation cabin, which can simulate environmental conditions at any longitude and dimension, would allow dynamometer testing to be performed indoors. Considering its high cost, a three-dimensional (3D) computational fluid dynamics (CFD) is needed to guide and/or complement experimental researches. As a result, the main objective of this study was to establish a 3D RANS model (i.e., reasonable computational cost and running time) that can provide in-cylinder details and predict the efficiency of a 6V150 diesel engine under varied operating conditions. A sector mesh approach was employed, considering only the compression, combustion, and expansion periods from intake valve closing to exhaust valve opening. The results indicated that the model simulated cylinder pressure agreed well with the experimental data, with relative errors of less than 6% during the primary compression, combustion, and expansion. Further, the model predicted heat release phasing was inconsistent with the experimental results, with absolute errors of less than one crank angle degree for peak pressure location, CA50, and ignition delay. In addition, the multidimensional model captured the effects of environmental pressure and temperature on spray formation (i.e., the dominant phenomenological event). Moreover, the model reasonably reproduced the effects of engine control variables on performance and emissions. All these observations demonstrated the validity of the selection and calibration of geometry, chemistry, and submodels including turbulence, spray, heat transfer, combustion, etc. Overall, the model was deemed capable of predicting combustion characteristics under extreme conditions, including high-temperature, high-cold, and high-altitude environments, which can facilitate the development of smart engines.

Influence of tumble and TKE on combustion, fuel economy, and emissions of a single cylinder motorcycle engine

The impact of gasoline engines on improving fuel consumption and reducing emissions has received increasing attention around the world, and emissions regulations have become stricter. However, complex techniques in engine improvement increase costs. The purpose of this study is to develop or improve the design of the intake geometry without additional cost to improve the engine thermal efficiency, thereby improving fuel economy and emissions. In this study, emissions and fuel consumption of a 125 c.c. commercially available motorcycle was investigated. In addition to modifying the intake and valve angles and maintaining the intake air volume, a software for computational fluid dynamics (CFD) was used for steady-state and transient analysis of the in-cylinder flow field, tumble ratio and turbulence kinetic energy (TKE), and the results were compared with the data of the experimental platform. The burn duration of the engine, indicated mean effective pressure (IMEP), indicated specific total hydrocarbons (ISHC), nitrogen oxide (ISNOx) and carbon monoxide (ISCO) were measured on the bench. The transient predicted results show that the tumble ratio is a maximum increase of 27.82% at 656 crank angle (CA) degrees near the top dead center (TDC) on the compression stroke. In the ignition area within 5°–20° before top dead center (BTDC), average of the turbulence kinetic energy (TKE) was 120.37 m2/s2, distributed hot area was wide and close to the ignition position. In the steady-state measurement, it was verified that the tumble ratio was significantly improved by modifying inlet, the same trend as the analysis result. In the bench test for full load measurement, the average of IMEP increased by 10.92%, indicated specific fuel consumption (ISFC) improved by 11.7%, burn duration increased by 25.27%, ISCO improved by 43.41%, and ISHC improved by 64.33%. For portion load measurement, the average of ISFC improved by 2.16%, burn duration increased by 24.84%, ISCO improved by 43.44%, ISHC improved by 17.7% and ISNO improved by 12.89%. Based on the results, the tumble and TKE were improved by optimizing the angle between the intake valve and the intake port. The ISFC of model B was significantly improved under the two states. The ignition delay time was longer, and the overall burn duration was much improved. When it came to emissions, the ISCO and ISHC were significantly improved, and the ISNO was much higher at full load but lower at partial load due to the engine temperature and engine loads. At partial loads, the high tumble did benefit the combustion, fuel economy and emissions of a single-cylinder motorcycle engine.

Experimental investigation on combustion behaviour, performance and emission of fusel oil-gasoline blends using turbocharged SI engine

Because of rising energy demand and pollution concerns in the transportation and industrial sectors, alternative fuel development is critical. The fusel oil, which is a by-product of ethanol distillation molasses, is receiving a lot of interest. The combustion characteristics, performance, and emissions of a 1.8L turbocharged four-cylinder, port injection, spark-ignition engine will be used to compare fusel oil blends with gasoline in this study. The experiment was carried out at a constant engine speed of 2000 rpm with a throttle load of 10-40%. Four samples with various ratios of gasoline combined with fusel oil were tested (100% gasoline, 10%, 20%, and 30% are referred to as F0, F10, F20, and F30 respectively). As a result, compared to gasoline, fusel oil blends increase Brake Specific Fuel Consumption (BSFC) by 5-22%. In comparison to gasoline, the combustion behaviour of in-cylinder pressure, Rate of Heat Release (ROHR), Rate Of Pressure Rise (ROPR), and Mass Fraction Burn (MFB) shows an early 2-3 Degree Crank Angle (CAD). Due to differences in attributes and oxygen content, the Brake Thermal Efficiency (BTE) of combustion utilising fusel oil blends suffers a modest drop of 13-16%. When compared to gasoline, fusel oil blends emit 3-4% less hydrocarbon (HC), 7.5-24.5% less carbon monoxide (CO), and 18-36% less nitrogen oxide (NOx). To summarise, fusel oil blends without water extraction blended with gasoline have a substantial impact on turbocharger engine functioning.

Numerical analysis of soot emissions from gasoline-ethanol and gasoline-butanol blends under gasoline compression ignition conditions

In the present work, computational fluid dynamics (CFD) simulations of a single-cylinder gasoline compression ignition (GCI) engine were performed to investigate the impact of blending two biofuels, ethanol and n-butanol, with gasoline on the trade-off between combustion phasing and soot emissions under low load conditions. In order to represent market gasoline (RD5-87), a four-component toluene primary reference fuel (TPRF) + ethanol (ETPRF) surrogate (with 20% ethanol by mole; E20) was formulated using a neural network based octane predictor such that the surrogate had the same ethanol content, Research Octane Number (RON) and Octane Sensitivity (S). In addition, a novel skeletal kinetic mechanism for ETPRF and TPRF + n-butanol (BTPRF) blends, incorporating polycyclic aromatic hydrocarbon (PAH) chemistry, was developed. A three-dimensional (3D) engine CFD formulation employing the skeletal mechanism, adaptive mesh refinement (AMR), finite-rate chemistry approach, and hybrid method of moments (HMOM) was adopted to capture the in-cylinder combustion phenomena and soot emissions. The engine CFD model was validated against RD5-87 experimental data for a broad range of start-of-injection (SOI) timings (-21/-27/-36/-45 crank angle degrees (CAD) after top-dead-center (aTDC)), with respect to in-cylinder pressure, heat release rate, combustion phasing, and soot emissions. The closed-cycle simulation results were analyzed to elucidate the non-monotonic trend of soot emissions versus SOI timing: SOI-36 > SOI-45 > SOI-21 > SOI-27. Thereafter, the validated CFD model was employed to simulate the combustion of a gasoline-ethanol blend with 45% (by mole) ethanol (E45) and a gasoline-butanol blend with 45% (by mole) n-butanol (B45) under the same operating conditions to study the effects of fuel composition and SOI timing on combustion phasing and soot emissions. The sooting propensity followed the trend: B45 > E20 > E45 at all SOI timings. Overall, it was observed that the autoignition propensity was primarily related to fuel chemistry. On the other hand, sooting propensity showed strong coupling with both fuel chemistry and physical properties, with greater impact of fuel physical properties at advanced SOI timings.

Spark ignition timing effects on a converted diesel engine using natural gas: A numerical study

Since it is not expected to switch to fully electric and/or fuel cell vehicles in the near future, the search for alternative fuels for systems using internal combustion engines has accelerated. At the forefront of these studies is the use of natural gas instead of diesel fuel in on-road, off-road vehicles, or stationary power generation plants. Diesel engines with their special combustion chamber (i.e. bowl in-piston) can be converted to run entirely on natural gas by installing a natural gas fuel injector on the intake manifold and a spark plug instead of a diesel fuel injector. In this study, in-cylinder combustion characteristics, performance, and emission values for different Spark Ignition Time (SIT) of natural gas usage at 2300 rpm and full load in a tractor engine with a compression ratio of 17.5:1 were investigated numerically using ANSYS Forte three-dimensional analysis program. G-equation combustion model, RANS k-ε turbulence model, and methane chemical kinetic mechanism representing natural gas consisting of 29 species and 171 equations (a reduced mechanism) were used. First SIT was accepted as a 719.5 Crank Angle Degree (CAD) which is diesel injection start time. As a result, due to the special shape of the combustion chamber of diesel engines (re-entrant bowl in-piston), it was seen that the flame was faster and thicker in the bowl, while it was slower and thinner in the squish zone. With the advanced of SIT, the in-cylinder pressure ratio increased. By taking SIT too advanced (i.e. 690, 695, and 700 CAD SIT), more than one peak formation was observed in the heat release graph depending on the combustion characteristic. With the effect of both natural gas use and SIT, it was observed that HC and CO formations were almost not seen, while NOX formation remains above a certain level.

An experimental study of performance, combustion and emissions characteristics of an ethanol HCCI engine using water injection

Homogeneous charge compression ignition (HCCI), also known as Controlled Auto-Ignition (CAI), enables combustion with high fuel conversion efficiency and low NOX emissions. It can benefit both spark and compression ignition engines and lessens the demand for expensive exhaust after-treatment systems. However, the HCCI application is restricted due to a limited operating range. Water injection can tackle this problem, which enables higher loads without excessive heat release rates. Although already reported in spark-ignited engines, water injection is still a novelty for HCCI combustion. The water injection strategy is not fully developed for HCCI engines, especially fueled with renewable fuels and using different methods to achieve CAI conditions. Hence, this paper studied the performance, combustion, and emissions characteristics of an ethanol HCCI engine using water injection and total exhaust gas recycling from an adjacent diesel cylinder. HCCI combustion was attained via direct recirculation of exhaust gases from a diesel cylinder, serving as a heat and active radical source for the ethanol charge auto-ignition. Water injection was used for combustion phasing control and load expansion. Detailed combustion and heat release analyses were performed. During the experiments, combustion phasing (CA50) ranged from 2 to 8 crank angle degrees (CAD) ATDC. Water injection reduced the heat release rates and prevented knock, keeping the in-cylinder temperatures below 1850 K. The results indicated that water injection effectively controlled combustion phasing and heat release rate, increasing the maximum operational load threefold. The combustion duration increased with water injection, varying from 6.6 CAD at high loads to 17.0 CAD at low loads. The indicated conversion efficiency was 27% at low loads and achieved the maximum of 39% at 6 bar of indicated mean effective pressure (IMEP). The NOX emissions formed in ethanol HCCI combustion were lower than 0.8 g/kWh.

Study of Spray Behaviors to Correlate with Engine Performance and Emissions of a Diesel Engine Using Canola-Based Biodiesel

The use of renewable biodiesel fuel in diesel engines can reduce the demand for depleting fossil fuels and reduce harmful emissions to the environment. In this research, an engine simulation is conducted using ANSYS Forte software, which allows for visualization of the spray inside the combustion chamber. The results show that biodiesel has higher liquid and vapor penetration lengths, higher droplet mass and diameter, and a longer breakup length. Molecular images of fuel molecules show that the temperature of biodiesel molecules is 141 °C lower than diesel molecules at 709 degree crank angle (°CA). These characteristics result in an extended evaporation time for biodiesel, consequently leading to poorer performance. Additionally, increased penetration length can lead to carbon deposits inside the combustion chamber. Therefore, such inefficiencies of biodiesel spray properties lead to lower combustive performance than diesel. In terms of performance, on average, biodiesel produces 16.9% lower power and 19.9% higher brake specific fuel consumption. On average, the emissions of CO, CO2, and HC of biodiesel are 17.8%, 3.41%, and 23.5% lower and NOx is 14.39% higher than the corresponding values obtained for pure diesel, respectively. In-cylinder combustion analyses show that the peak pressure of biodiesel is 0.5 MPa lower, the peak cycle temperature is 36 °C lower, the ignition delay is 4 °CA longer, the peak heat release rate is 16.5 J/deg. higher, and the combustion duration is 5.96 °CA longer compared to diesel combustion.

A study on the feasibility of bergamot peel oil-gasoline blends for spark-ignition engines

In this research, an ample attempt was made to make use of oil extracted from bergamot fruit peel, which can be regarded as a renewable energy source. A systematic experimental approach was adopted to evaluate the feasibility of bergamot peel oil (BGT) as a substitute for gasoline fuel in spark-ignition (SI) engine applications. The oil derived from the rinds of the bergamot fruit was blended in gasoline on a volume basis in the ratios of 10:90, 20:80, 30:70, and 40:60 and experimentally tested in a multi-point fuel injection (MPFI) installed SI engine. The fuel properties of the BGT and its blends were tested. Endoscopic visualization technique was used to analyze the spatial flame distribution on a crank angle basis for the gasoline and bergamot blends. Also, the performance, combustion, and emission characteristics of bergamot-gasoline blends were evaluated, and the results were compared with sole gasoline at various engine brake powers. The endoscopic results revealed that bergamot-gasoline blends exhibited higher flame spread than sole gasoline. The performance study revealed that the brake thermal efficiency and specific fuel consumption exhibited by bergamot-gasoline blends were almost equivalent to that of sole gasoline. The mean in-cylinder pressure was marginally higher, and peak pressure crank angle degree was slightly advanced for bergamot-gasoline blends in comparison to that of gasoline fuel. With an increasing concentration of BGT in the blend, the hydrocarbon (HC) and carbon monoxide (CO) emission decreased at the expense of nitrogen oxides (NOx). Furthermore, BGT exhibits a research octane number (RON) of 80 and a calorific value comparable to that of gasoline, making it a potential candidate for SI engines. From the outcome of this study, it can be concluded that BGT could be a promising alternate biofuel for the partial replacement of gasoline in SI engines.

Real-time abnormality detection and classification in diesel engine operations with convolutional neural network

In this paper, we propose a real-time diagnostic method using a convolutional neural network (CNN) to detect cylinder misfires and engine load conditions in multi-cylinder internal combustion (IC) diesel engines. To enhance engine efficiency and reliability, it is necessary to detect and classify multiple irregularities in engine operation, such as misfires and changes in load conditions. Optimized combustion parameter setting increases engine efficiency, which depends on the engine load conditions. Similarly, misfire detection prevents engine damage and increases fuel efficiency and reliability of the engine. Previous works investigated misfire detection while ignored the change in engine operating conditions that affects the engine efficiency. This work presents a real-time CNN-based method to detect misfires and load changes together in engine operations by analyzing the IC process. First, the sensor signal is pre-processed to extract a primary signal and translate it into a crank angle degree (CAD) signal, which represents a complete cycle of the IC process in the engine. After that, a CNN is designed for multi-class classification and trained using one-dimensional CAD vectors, which combines a feature extraction capability and pattern recognition in a single learner. The proposed CNN-based method detects and classifies multiple abnormalities in engine operations with an accuracy of more than 99% and low generalization error. The designed CNN uses a single convolutional layer for feature extraction resulting in more efficient systems in terms of performance and speed.

On the use of particle image velocimetry (PIV) data for the validation of Reynolds averaged Navier-Stokes (RANS) simulations during the intake process of a spark ignition direct injection (SIDI) engine

Computational fluid dynamics (CFD) simulations of the in-cylinder flow field are widely used in the design of internal combustion engines (ICEs) and must be validated against experimental measurements to enable a robust predictive capability. Such validation is complicated by the presence of both large-scale cycle-to-cycle variations and small-scale turbulent fluctuations in experimental measurements of in-cylinder flow fields. Reynolds averaged Navier-Stokes (RANS) simulations provide overall flow structures with acceptable accuracy and affordable computational cost for widespread industrial applications. Due to the nature of averaging physical parameters in RANS, its validation against experimental results obtained by particle image velocimetry (PIV) requires consideration of how best to average or filter the measured turbulent flows. In this paper, PIV measurements on the cross-tumble plane were recorded every five crank angle degrees for [Formula: see text] cycles during the intake process of a motored, optically accessible spark ignition direct injection (SIDI) engine. Several methods including ensemble averaging, speed-based averaging and low-order proper orthogonal decomposition (POD) reconstruction were applied to remove the fluctuations from experimental PIV vector fields and thus enable comparison to RANS simulations. Quantitative comparison metrics were used to evaluate the performances of each method in representing the intake jet. Recommendations are made on how to provide a fair validation between measured data and simulation results in highly fluctuating flow fields such as the engine intake jet.

Development and validation of a n‐butanol reduced chemical kinetic mechanism under engine relevant conditions

AbstractA n‐butanol reduced mechanism (60 species and 306 reactions) was developed using the direct relation graph with error propagation and isomer lumping methods. Sensitivity analysis (SA) was then performed to identify reactions that were sensitive to the ignition delay (ID) for the adjustments of the pre‐exponential factor to replicate the experimental ID times. As compared with the experimental measurements at initial temperatures of 343–1350 K, initial pressures of 0.02–80 bar, and equivalence ratios of 0.5–2.0, the maximum deviation for the predictions by the n‐butanol reduced mechanism was at 37.75% for the ID times, 8 cm/s for the laminar flame speed, and a factor of three for both the species concentration profiles under jet‐stirred reactor and premixed laminar flame. Furthermore, a maximum deviation of 2.5 crank angle degrees in combustion phasing was obtained when the reduced mechanism was benchmarked against the detailed mechanism under homogeneous charge compression ignition (HCCI) conditions at initial temperature of 413 K, initial pressure of 1 bar, and equivalence ratios of 0.5–2.0. Despite these deviations, the low temperature IDs and the laminar flame speed predicted by the present reduced mechanism were in better agreement to the experimental measurements than the existing n‐butanol reduced mechanisms of comparable sizes. Hence, this collectively indicates that improvements were made to the present reduced mechanism, particularly for the low‐temperature reactions. The n‐butanol reduced mechanism was also compared with gasoline and diesel surrogates under 0D HCCI simulations. The results indicate that the combustion characteristics of n‐butanol is closer to gasoline than to diesel. This suggests that n‐butanol could safely replace gasoline fuel in neat form while it is more suitable to be blended with diesel fuel to maintain engine performance and prevent any adverse effects on the engine.

Impact of low reactivity fuel type on low load combustion, emissions, and cyclic variations of diesel-ignited dual fuel combustion

In this study, cyclic variations in dual fuel combustion with diesel ignition of three different low reactivity fuels (methane, propane, and gasoline) are examined under identical operating conditions. Experiments were performed on a single cylinder research engine (SCRE) at a low load of 3.3 bar brake mean effective pressure (BMEP). The start of injection (SOI) of diesel was varied from 280 to 330 absolute crank angle degrees (CAD). Engine speed, rail pressure, and boost pressure were held constant at 1500 rpm, 500 bar, and 1.5 bar, respectively. The energy substituted by the low reactivity fuel was fixed at 80% of the total energy input. It was found that diesel-methane (DM) and diesel-propane (DP) combustion were affected by diesel mixing to a greater extent than diesel-gasoline (DG) combustion due to the higher reactivity of gasoline. The magnitude of low temperature heat release was greatest for DG combustion followed by DM and DP combustion for all SOIs. The ignition delay for DG combustion was the shortest, followed by DM and DP combustion. DM and DP combustion exhibited more cyclic variations than DG combustion. Cyclic variations decreased for DM and DP combustion when SOI was advanced; however, DG combustion cyclic variations remained essentially constant for all SOIs. Earlier SOIs (280, 290, 300, and 310 CAD) for DM and (280, 290, and 300 CAD) for DP combustion indicated some prior-cycle effects on the combustion and IMEP (i.e. some level of determinism).

Development and Experimental Validation of an Adaptive, Piston-Damage-Based Combustion Control System for SI Engines: Part 2—Implementation of Adaptive Strategies

This work focuses on the implementation of innovative adaptive strategies and a closed-loop chain in a piston-damage-based combustion controller. In the previous paper (Part 1), implemented models and the open loop algorithm are described and validated by reproducing some vehicle maneuvers at the engine test cell. Such controller is further improved by implementing self-learning algorithms based on the analytical formulations of knock and the combustion model, to update the fuel Research Octane Number (RON) and the relationship between the combustion phase and the spark timing in real-time. These strategies are based on the availability of an on-board indicating system for the estimation of both the knock intensity and the combustion phase index. The equations used to develop the adaptive strategies are described in detail. A closed-loop chain is then added, and the complete controller is finally implemented in a Rapid Control Prototyping (RCP) device. The controller is validated with specific tests defined to verify the robustness and the accuracy of the adaptive strategies. Results of the online validation process are presented in the last part of the paper and the accuracy of the complete controller is finally demonstrated. Indeed, error between the cyclic and the target combustion phase index is within the range ±0.5 Crank Angle degrees (°CA), while the error between the measured and the calculated maximum in-cylinder pressure is included in the range ±5 bar, even when fuel RON or spark advance map is changing.

Analysis of the Influence of CO2 Concentration on a Spark Ignition Engine Fueled with Biogas

Biogas is one of the alternative solutions that could reduce the usage of fossil fuels and production of greenhouse gas emissions, as biogas is considered as an alternative fuel with a short carbon cycle. During biogas production, organic matter is decomposed during an anaerobic digestion process. Biogas mainly consists of methane and carbon dioxide, of which the ratio varies depending on the raw material and parameters of the production process. Therefore, engine parameters should be adjusted in relationship with biogas composition. In this research, a spark ignition engine was tested for mixtures of biogas with 0 vol%, 20 vol%, 40 vol% and 50 vol% of CO2. In all experiments, two cases of spark timing (ST) were used; the first one is a constant spark timing (26 crank angle degrees (CAD) before top dead center (BTDC)) and the second one is an advanced spark timing (optimal for biogas mixture). Results show that increasing the CO2 concentration and using constant spark timing increases the mass burned fraction combustion duration by 90%, reduces the in-cylinder pressure and leads to a reduction in the brake thermal efficiency and nitrogen oxides emissions at all measurement points. However, the choice of optimal spark timing increases the brake thermal efficiency as well as hydrocarbon and CO2 emission.

An experimental based artificial neural network modeling in prediction of optimum combustion, performance, and emission from diesel engine operated with three biodiesels

Purpose This study aims to improve the performance and to regulate the harmful emission from the diesel engine. For this purpose, palm oil biodiesel (POBD), waste cooking biodiesel (WCBD) and animal fat biodiesel (AFBD) are used for examination. Design/methodology/approach The transesterification process was followed to convert the three raw oils into biodiesels and the experiments are conducted at various loads with fixed 25 rps. Diesel as a reference fuel and three neat biodiesels are tested for emissions and performance. By training the experimental results in an artificial neural network (ANN), the best biodiesel was predicted. Findings The biodiesels are tested for significant fuel properties with the American Society for testing and materials standards and observed that kinematic viscosity, density and cetane number are recorded higher than diesel fuel. The fatty acid composition (FAC) from chromatography reveals the presence of unsaturated FAC is more in POBD (70.89%) followed by WCBD (57.67%) and AFBD (43.13%). The combustion pressures measured at every degree of crank angle reveal that WCBD and AFBD exhibited on far with diesel fuel. Compared to diesel fuel WCBD and AFBD achieved maximum brake thermal efficiency of 31.99% and 30.93% at 75% load. However, there is a penalty in fuel consumption and NOx emissions from biodiesels. On the other hand, low carbon monoxide, unburnt hydrocarbon emissions and exhaust smoke are reported for biodiesels. Finally, WCBD was chosen as the best choice based on ANN modeling prediction results. Originality/value There is no evident literature on these three neat biodiesel applications with the mapping of ANN modeling.

Effects of internal/external EGR and combustion phase on gasoline compression ignition at low-load condition

Abstract A single-cylinder test engine model was built by GT-Power software, and the effects of internal exhaust gas recirculation (i-EGR), external EGR (e-EGR), i-EGR/e-EGR coupling and the crank angle degree at which 50% of total heat loss has taken place (CA50) on combustion and emission characteristics of gasoline compression ignition at low-load condition were analysed. The results show that the ignition delay period with e-EGR was extended slightly with the increased EGR ratio, while that with i-EGR strategy first shortened and then extended, and that the optimised indicated thermal efficiency could be achieved using a small amount of i-EGR. With the same EGR ratio, nitrogen oxide (NO X ) emission is more likely to be suppressed by i-EGR, while soot emission was more deteriorated, and the superior trade-off relationship between carbon monoxide (CO)/hydrocarbon (HC) emissions and NO X emission was attained by the combination of lower i-EGR ratios and CA50 closed to top dead centre. When using i-EGR/e-EGR coupling with total EGR ratio being fixed, the indicated thermal efficiency was decreased by increasing i-EGR ratio, while the lower NO X , CO and HC emissions could be realised, but only with the consequence that soot emission increased.