scholarly journals Cycle-skipping strategy with intake air cut off for natural gas fueled Si engine

2021 ◽  
Vol 104 (3) ◽  
pp. 003685042110310
Author(s):  
Erdal Tunçer ◽  
Tarkan Sandalci ◽  
Saban Pusat ◽  
Özgün Balcı ◽  
Yasin Karagöz
Keyword(s):  
Natural Gas ◽  
Normal Condition ◽  
Engine Performance ◽  
Operating Conditions ◽  
Cylinder Pressure ◽  
Continuous Change ◽  
Indicated Mean Effective Pressure ◽  
Rate Of Heat Release ◽  
Hc Emissions ◽  
Inlet Manifold

In this study, cycle-skipping was investigated for a natural gas engine which has single cylinder, unsupercharged with 1.16 L volume and spark ignition. Additionally, inlet manifold air was switched off during cycle-skipping to minimize pumping losses. Thus, cycle-skipping strategy was carried out, and its effects on emission and engine performance were investigated. Indicated mean effective pressure, indicated efficiency, specific emissions (CO, HC, and NOX) and combustion characteristics (in-cylinder pressure and rate of heat release) were investigated in the study. As a result of performed study, it is predicted that a significant improvement can be achieved in indicated thermal efficiency as 22.8% and 13.4% by different cycle-skipping strategies. However, there is not a continuous change in emissions for different cycle-skipping strategies. While CO and NOX emissions increased in 3N1S (three normal, one cycle-skip) condition, HC emissions decreased in accordance with normal condition. For both cycle-skipping strategies, all the emissions have an increase in accordance with normal condition. In 3N1S and 2N1S (two normal, one cycle-skip) cycle skip engine operating conditions, compared to engine operating under normal condition, CO emissions increased by 14.7 and 51.7 times, respectively. In terms of HC emissions, while emission values decreased by 27.8% under 3N1S operating conditions, they increased by 67.2% under 2N1S operating conditions. Finally, in 3N1S and 2N1S cycle skip engine operating conditions, NOx emissions increased by 3.7 and 6.9 times, respectively, compared to normal operating condition. Another significant result of this study is that peak in-cylinder pressure increased as the cycle-skipping rate increased.

scholarly journals Engine Malfunctioning Conditions Identification through Instantaneous Crankshaft Torque Measurement Analysis

2021 ◽  
Vol 11 (8) ◽  
pp. 3522
Author(s):  
Konstantinos-Marios Tsitsilonis ◽  
Gerasimos Theotokatos
Keyword(s):  
Operating Conditions ◽  
Cylinder Pressure ◽  
Dynamics Model ◽  
Engine Model ◽  
Measurement Analysis ◽  
Start Of Injection ◽  
Rate Of Heat Release ◽  
Relationship Of ◽  
Diagnostic Measurement ◽  
The Relationship

In this study a coupled thermodynamics and crankshaft dynamics model of a large two-stroke diesel engine was utilised, to map the relationship of the engine Instantaneous Crankshaft Torque (ICT) with the following frequently occurring malfunctioning conditions: (a) change in Start of Injection (SOI), (b) change in Rate of Heat Release (RHR), (c) change in scavenge air pressure, and (d) blowby. This was performed using frequency analysis on the engine ICT, which was obtained through a series of parametric runs of the coupled engine model, under the various malfunctioning and healthy operating conditions. This process demonstrated that engine ICT can be successfully utilised to identify the distinct effects of malfunctions (c) or (d), as they occur individually in any cylinder. Furthermore by using the same process, malfunctions (a) and (b) can be identified as they occur individually for any cylinder, however there is no distinct effect on the engine ICT among these malfunctions, since their effect on the in-cylinder pressure is similar. As a result, this study demonstrates the usefulness of the engine ICT as a non-intrusive diagnostic measurement, as well as the benefits of malfunctioning conditions mapping, which allows for quick and less resource intensive identification of engine malfunctions.

Two-Stroke Marine Diesel Engine Variable Injection Timing System Performance Evaluation and Optimum Setting for Minimum Fuel Consumption at Acceptable NOx Levels

2014 ◽  
Author(s):  
Dimitrios T. Hountalas ◽  
Spiridon Raptotasios ◽  
Antonis Antonopoulos ◽  
Stavros Daniolos ◽  
Iosif Dolaptzis ◽  
...  
Keyword(s):  
Diesel Engine ◽  
Fuel Consumption ◽  
Engine Performance ◽  
Operating Conditions ◽  
Specific Fuel Consumption ◽  
Injection Timing ◽  
Nox Emissions ◽  
Pressure Measurements ◽  
Cylinder Pressure ◽  
Start Of Injection

Currently the most promising solution for marine propulsion is the two-stroke low-speed diesel engine. Start of Injection (SOI) is of significant importance for these engines due to its effect on firing pressure and specific fuel consumption. Therefore these engines are usually equipped with Variable Injection Timing (VIT) systems for variation of SOI with load. Proper operation of these systems is essential for both safe engine operation and performance since they are also used to control peak firing pressure. However, it is rather difficult to evaluate the operation of VIT system and determine the required rack settings for a specific SOI angle without using experimental techniques, which are extremely expensive and time consuming. For this reason in the present work it is examined the use of on-board monitoring and diagnosis techniques to overcome this difficulty. The application is conducted on a commercial vessel equipped with a two-stroke engine from which cylinder pressure measurements were acquired. From the processing of measurements acquired at various operating conditions it is determined the relation between VIT rack position and start of injection angle. This is used to evaluate the VIT system condition and determine the required settings to achieve the desired SOI angle. After VIT system tuning, new measurements were acquired from the processing of which results were derived for various operating parameters, i.e. brake power, specific fuel consumption, heat release rate, start of combustion etc. From the comparative evaluation of results before and after VIT adjustment it is revealed an improvement of specific fuel consumption while firing pressure remains within limits. It is thus revealed that the proposed method has the potential to overcome the disadvantages of purely experimental trial and error methods and that its use can result to fuel saving with minimum effort and time. To evaluate the corresponding effect on NOx emissions, as required by Marpol Annex-VI regulation a theoretical investigation is conducted using a multi-zone combustion model. Shop-test and NOx-file data are used to evaluate its ability to predict engine performance and NOx emissions before conducting the investigation. Moreover, the results derived from the on-board cylinder pressure measurements, after VIT system tuning, are used to evaluate the model’s ability to predict the effect of SOI variation on engine performance. Then the simulation model is applied to estimate the impact of SOI advance on NOx emissions. As revealed NOx emissions remain within limits despite the SOI variation (increase).

Model-Based Calibration of a Biogas Engine Control System

2012 ◽  
Author(s):  
Michael Flory ◽  
Joel Hiltner ◽  
Clay Hardenburger
Keyword(s):  
Control System ◽  
Natural Gas ◽  
Electrical Power ◽  
Engine Performance ◽  
Operating Conditions ◽  
High Quality ◽  
Model Based ◽  
Crank Angle ◽  
Short Period ◽  
Exhaust Gas Emission

Pipeline natural gas composition is monitored and controlled in order to deliver high quality, relatively consistent gas quality in terms of heating value and detonation characteristics to end users. The consistency of this fuel means gas-fired engines designed for electrical power generation (EPG) applications can be highly optimized. As new sources of high quality natural gas are found, the demand for these engines is growing. At the same time there is also an increasing need for EPG engines that can handle fuels that have wide swings in composition over a relatively short period of time. The application presented in this paper is an engine paired with an anaerobic digester that accepts an unpredictable and varying feedstock. As is typical in biogas applications, there are exhaust stream contaminants that preclude the use of an oxygen or NOx sensor for emissions feedback control. The difficulty with such a scenario is the ability to hold a given exhaust gas emission level as the fuel composition varies. One challenge is the design of the combustion system hardware. This design effort includes the proper selection of compression ratio, valve events, ignition timing, turbomachinery, etc. Often times simulation tools, such as a crank-angle resolved engine model, are used in the development of such systems in order to predict performance and reduce development time and hardware testing. The second challenge is the control system and how to implement a robust control capable of optimizing engine performance while maintaining emissions compliance. Currently there are limited options for an OEM control system capable of dealing with fuels that have wide swings in composition. Often times the solution for the engine packager is to adopt an aftermarket control system and apply this in place of the control system delivered on the engine. The disadvantage to this approach is that the aftermarket controller is not calibrated and so the packager is faced with the task of developing an entire engine calibration at a customer site. The controller must function well enough that it will run reliably during plant start-up and then eventually prove capable of holding emissions under typical operating conditions. This paper will describe the novel use of a crank-angle resolved four-stroke engine cycle model to develop an initial set of calibration values for an aftermarket control system. The paper will describe the plant operation, implementation of the aftermarket controller, the model-based calibration methodology and the commissioning of the engine.

Investigating the Effects of Engine Operating Conditions on the Cyclic Variability of a Commercial Flex-Fuel Engine

2019 ◽  
Author(s):  
Fazal Um Min Allah ◽  
Caio Henrique Rufino ◽  
Waldyr Luiz Ribeiro Gallo ◽  
Clayton Barcelos Zabeu
Keyword(s):  
Spark Ignition ◽  
Operating Conditions ◽  
Spark Ignition Engine ◽  
Cylinder Pressure ◽  
Cyclic Variability ◽  
Indicated Mean Effective Pressure ◽  
Mass Fractions ◽  
Cyclic Variations ◽  
Flex Fuel ◽  
Hydrous Ethanol

Abstract The flex-fuel engines are quite capable of running on gasohol and hydrous ethanol. However, the in-cylinder cyclic variations, which are inherently present in spark-ignition (SI) engines, affect the performance of these engines. Therefore, a comprehensive analysis is required to evaluate the effects of in-cylinder cyclic variations of a flex-fuel engine. The experiments were carried out by using Brazilian commercial Gasohol E27 (mixture of 27% anhydrous ethanol in gasoline) and hydrous ethanol E95h (5% water by volume in ethanol) as fuels for a commercial flex-fuel spark ignition engine. A comparison between the cyclic variations of gasohol and hydrous ethanol is presented in this paper. Moreover, the effects of engine operating parameters (i.e., engine speed, engine load and relative air fuel ratio) on cyclic variations are also investigated. The acquired data of in-cylinder pressure and combustion durations are evaluated by carrying out a statistical analysis. The coefficient of variation for indicated mean effective pressure (IMEP) did not exceed the limit of 5% for all tested conditions. Higher cyclic variability of maximum in-cylinder pressure is observed for gasohol fuel and higher engine speeds. The variability of in-cylinder combustion is also evaluated with the help of different combustion stages, which are characterized by corresponding crank positions of 10%, 50% and 90% mass fractions burned.

The Effects of Intake Plenum Volume on the Performance of a Small Naturally Aspirated Restricted Engine

2009 ◽  
Author(s):  
Leonard J. Hamilton ◽  
Jim S. Cowart ◽  
Jasen E. Lee ◽  
Ryan E. Amorosso
Keyword(s):  
Steady State ◽  
Performance Metrics ◽  
Full Range ◽  
Engine Performance ◽  
Absolute Pressure ◽  
Cylinder Pressure ◽  
Formula Sae ◽  
Indicated Mean Effective Pressure ◽  
Competition Rules ◽  
The Impact

Intake tuning is a widely recognized method for optimizing the performance of a naturally aspirated engine for motorsports applications. Wave resonance and Helmholtz theories are useful for predicting the impact of intake runner length on engine performance. However, there is very little information in the literature regarding the effects of intake plenum volume. The goal of this study was to determine the effects of intake plenum volume on steady state and transient engine performance for a restricted naturally aspirated engine for Formula SAE (FSAE) vehicle use. Testing was conducted on a four cylinder 600 cc motorcycle engine fitted with a 20 mm restrictor in compliance with FSAE competition rules. Plenum sizes were varied from 2 to 10 times engine displacement (1.2 to 6.0 L) and engine speeds were varied from 3,000 to 12,500 RPM. Performance metrics including volumetric efficiency, torque and power were recorded at steady state conditions. Experimental results showed that engine performance increased modestly as plenum volume was increased from 2 to 8 times engine displacement (4.8L). Increasing plenum volume beyond 4.8L resulted in significant improvement in performance parameters. Overall, peak power was shown to increase from 54 kW to 63 kW over the range of plenums tested. Additionally, transient engine performance was evaluated using extremely fast (60 msec) throttle opening times for the full range of plenum sizes tested. In-cylinder pressure was used to calculate cycle-resolved gross indicated mean effective pressure (IMEPg) development during these transients. Interestingly, the cases with the largest plenum sizes only took 1 – 2 extra cycles (30–60 msec) to achieve maximum IMEPg levels when compared to the smaller volumes. In fact the differences were so minor that it would be doubtful that a driver would notice the lag. Additional metrics included time for the plenums to fill and an analysis of manifold absolute pressure (MAP) and peak in-cylinder pressure development during and after the throttle transient. Plenums below 4.8L completely filled even before the transient was completed.

Experimental Evaluation of Piston Assembly Friction Under Motored and Fired Conditions in a Gasoline Engine

2004 ◽  
Author(s):  
Riaz A. Mufti ◽  
Martin Priest
Keyword(s):  
Gasoline Engine ◽  
Operating Conditions ◽  
Cylinder Pressure ◽  
Connecting Rod ◽  
Friction Modifier ◽  
Indicated Mean Effective Pressure ◽  
Axial Forces ◽  
The Difference ◽  
Digital Channels ◽  
Piston Assembly

Piston assembly friction measurement has been carried out on a single cylinder gasoline engine using the IMEP (indicated mean effective pressure) method at realistic engine speeds and loads without any major engine modifications. Instantaneous and mean piston assembly friction were measured under motored and fired conditions at different lubricant temperatures. The forces acting on the piston assembly were carefully determinated by measuring the cylinder pressure, crankshaft angular velocity and strain in the connecting rod. The difference between the resulting gas pressure, inertia and connecting rod axial forces acting on the piston yields the piston assembly friction. To achieve this with confidence, an advanced instrumentation, telemetry and data acquisition system was designed and developed, giving special attention to the synchronisation and simultaneous sampling of analogue and digital channels. Experiments are reported for piston assembly friction at a range of engine operating conditions with different lubricant formulations, with and without a friction modifier.

A Comprehensive Study on Natural Gas HCCI Engine Response to Different Initial Conditions via a Thermo-Kinetic Engine Model

2009 ◽  
Author(s):  
Omid Jahanian ◽  
Seyed Ali Jazayeri
Keyword(s):  
Natural Gas ◽  
Initial Conditions ◽  
Chemical Species ◽  
Engine Performance ◽  
Operating Conditions ◽  
Zone Model ◽  
Operating Characteristics ◽  
Hcci Engine ◽  
Engine Model ◽  
Homogenous Charge Compression Ignition

Homogenous Charge Compression Ignition (HCCI) combustion is a promising concept to reduce engine emissions and fuel consumption. In this paper, a thermo-kinetic model is developed to study the operating characteristics of a natural gas HCCI engine. The zero-dimensional single zone model consist detail chemical kinetics of natural gas oxidation including 325 reactions with 53 chemical species, and is validated with experimental results of reference works for two different engines, Volvo TD 100 and Caterpillar 3500, in 5 operating conditions. Then, the influence of parameters such as manifold temperature/pressure and equivalence ratio on in-cylinder temperature/pressure trends and start of combustion is studied. Measurements for Volvo engine show that SOC occurs 3–5 CAD earlier with every 15K increase in initial temperature. These whole results are explained in detail to describe the engine performance thoroughly.

scholarly journals Modelling and Simulation of the Performance and Combustion Characteristics of a Locomotive Diesel Engine Operating on a Diesel–LNG Mixture

Energies ◽  
2021 ◽  
Vol 14 (17) ◽  
pp. 5318
Author(s):  
Imantas Lipskis ◽  
Saugirdas Pukalskas ◽  
Paweł Droździel ◽  
Dalibor Barta ◽  
Vidas Žuraulis ◽  
...  
Keyword(s):  
Engine Performance ◽  
Fuel Mixture ◽  
Combustion Characteristics ◽  
Cylinder Pressure ◽  
Diesel Locomotive ◽  
Compression Ignition Engine ◽  
Locomotive Engine ◽  
Rate Of Heat Release ◽  
Fuel Mixtures ◽  
Locomotive Diesel

The article describes a compression-ignition engine working with a dual-fuel system installed in diesel locomotive TEP70 BS. The model of the locomotive engine has been created applying AVL BOOST and Diesel RK software and engine performance simulations. Combustion characteristics have been identified employing the mixtures of different fuels. The paper compares ecological (CO2, NOx, PM) and energy (in-cylinder pressure, temperature and the rate of heat release (ROHR)) indicators of a diesel and fuel mixtures-driven locomotive. The performed simulation has shown that different fuel proportions increased methane content and decreased diesel content in the fuel mixture, as well as causing higher in-cylinder pressure and ROHR; however, in-cylinder temperature dropped. CO2, NOx and PM emissions decrease in all cases thus raising methane and reducing diesel content in the fuel mixture.

Random Forest Machine Learning Model for Predicting Combustion Feedback Information of a Natural Gas Spark Ignition Engine

2020 ◽  
Vol 143 (1) ◽  
Author(s):  
Jinlong Liu ◽  
Christopher Ulishney ◽  
Cosmin Emil Dumitrescu
Keyword(s):  
Machine Learning ◽  
Random Forest ◽  
Natural Gas ◽  
Engine Performance ◽  
Cost Effective ◽  
Learning Model ◽  
Operating Conditions ◽  
Control Variables ◽  
Feedback Information ◽  
Machine Learning Model

Abstract Engine calibration requires detailed feedback information that can reflect the combustion process as the optimized objective. Indicated mean effective pressure (IMEP) is such an indicator describing an engine’s capacity to do work under different combinations of control variables. In this context, it is of interest to find cost-effective solutions that will reduce the number of experimental tests. This paper proposes a random forest machine learning model as a cost-effective tool for optimizing engine performance. Specifically, the model estimated IMEP for a natural gas spark ignited engine obtained from a converted diesel engine. The goal was to develop an economical and robust tool that can help reduce the large number of experiments usually required throughout the design and development of internal combustion engines. The data used for building such correlative model came from engine experiments that varied the spark advance, fuel-air ratio, and engine speed. The inlet conditions and the coolant/oil temperature were maintained constant. As a result, the model inputs were the key engine operation variables that affect engine performance. The trained model was shown to be able to predict the combustion-related feedback information with good accuracy (R2 ≈ 0.9 and MSE ≈ 0). In addition, the model accurately reproduced the effect of control variables on IMEP, which would help narrow the choice of operating conditions for future designs of experiment. Overall, the machine learning approach presented here can provide new chances for cost-efficient engine analysis and diagnostics work.

Engine Performance and Emissions for a Heavy-Duty Diesel Engine Converted to Stoichiometric Natural Gas Operation

2020 ◽  
Author(s):  
Jinlong Liu ◽  
Christopher Ulishney ◽  
Cosmin E. Dumitrescu
Keyword(s):  
Natural Gas ◽  
Catalytic Converter ◽  
Combustion Process ◽  
Engine Performance ◽  
Intake Manifold ◽  
Heavy Duty ◽  
Indicated Mean Effective Pressure ◽  
Performance And Emissions ◽  
Heavy Duty Diesel ◽  
Ci Engines

Abstract Converting existing compression ignition (CI) engines to spark ignition (SI) operation can increase the use of natural gas (NG) in heavy-duty engine applications and reduce the reliance on petroleum fuels. Gas fumigation upstream of the intake manifold and the addition of a spark plug in place of the diesel injector to initiate and control the combustion process is a convenient approach for converting existing diesel engines to dedicated NG operation. Stoichiometric operation and a three-way catalytic converter can help the engine to comply with increasingly strict emission regulations. However, as the CI-to-SI conversion usually maintains the conventional geometry of a CI engine (i.e., maintains the flat cylinder head and the bowl-in piston), the goal of this study was to observe some of the effects that the diesel conversion to stoichiometric NG SI operation will have on the engine’s performance and emissions. Dynamometer tests were performed at a constant engine speed at 1300 rpm but various spark timings. The experimental results for a net indicated mean effective pressure ∼ 6.7 bar showed that ignition timing did not affect the end of combustion due to the slow-burn inside the squish. Moreover, the less-optimal conditions inside the squish led to increased carbon monoxide (CO) and unburned hydrocarbon (UHC) emissions. While the combustion event was stable with no signs of knocking at the medium load conditions investigated here, the results suggest that the engine control needs to optimize the mass fraction trapped inside the squish region for a higher efficiency and lower emissions.

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