Determination of a most representative cycle from cylinder pressure ensembles via statistical method using distribution skewness

2021 ◽  
pp. 146808742110655
Author(s):  
Jorge Pulpeiro González ◽  
Carrie M Hall ◽  
Christopher P Kolodziej
Keyword(s):  
Statistical Method ◽  
Combustion Engine ◽  
Pressure Rise ◽  
Operating Conditions ◽  
Cylinder Pressure ◽  
Pressure Trace ◽  
Combustion Knock ◽  
Engine Operating Condition ◽  
Combustion Processes

In internal combustion engine research, cylinder pressure measurements provide valuable information about the underlying thermodynamic and combustion processes, and are typically collected in ensembles of several 100 traces. Although in some particular fields of combustion research all traces are analyzed, in most cases only one trace is studied because analyzing all the traces is impractical due to the large number of collected samples. Instead, an ensemble-averaged pressure trace is commonly calculated and used for analysis. However, this pressure trace is highly smoothed and dynamic information is lost during the averaging process. With the average trace, pressure rise rates are lower and pressure oscillations such as the ones resulting from combustion knock are lost. In this work, a statistical method was developed to determine the “most representative cycle,” which is the cycle from the ensemble that has the pressure trace most representative of the engine operating condition. Eleven characteristic parameters are computed from each pressure trace and probabilistic distributions are obtained for each of the parameters using all the traces in the ensemble. Finally, the most representative cycle is selected by means of a cost function minimization. The benefits of this method are illustrated using experimental data from four very different engine platforms, under four different combustion modes and over a range of operating conditions.

Ethers and esters as alternative fuels for internal combustion engine: A review

2021 ◽  
pp. 146808742110464
Author(s):  
Yang Hua
Keyword(s):  
Alternative Fuels ◽  
Combustion Engine ◽  
Combustion Process ◽  
Pressure Rise ◽  
Engine Performance ◽  
Internal Combustion ◽  
Operating Conditions ◽  
Future Research ◽  
Particulate Emissions ◽  
Ic Engine

Ether and ester fuels can work in the existing internal combustion (IC) engine with some important advantages. This work comprehensively reviews and summarizes the literatures on ether fuels represented by DME, DEE, DBE, DGM, and DMM, and ester fuels represented by DMC and biodiesel from three aspects of properties, production and engine application, so as to prove their feasibility and prospects as alternative fuels for compression ignition (CI) and spark ignition (SI) engines. These studies cover the effects of ether and ester fuels applied in the form of single fuel, mixed fuel, dual-fuel, and multi-fuel on engine performance, combustion and emission characteristics. The evaluation indexes mainly include torque, power, BTE, BSFC, ignition delay, heat release rate, pressure rise rate, combustion duration, exhaust gas temperature, CO, HC, NOx, PM, and smoke. The results show that ethers and esters have varying degrees of impact on engine performance, combustion and emissions. They can basically improve the thermal efficiency of the engine and reduce particulate emissions, but their effects on power, fuel consumption, combustion process, and CO, HC, and NOx emissions are uncertain, which is due to the coupling of operating conditions, fuel molecular structure, in-cylinder environment and application methods. By changing the injection strategy, adjusting the EGR rate, adopting a new combustion mode, adding improvers or synergizing multiple fuels, adverse effects can be avoided and the benefits of oxygenated fuel can be maximized. Finally, some challenges faced by alternative fuels and future research directions are analyzed.

scholarly journals Closed-loop control of a dual-fuel engine working with different combustion modes using in-cylinder pressure feedback

2019 ◽  
Vol 21 (3) ◽  
pp. 484-496 ◽  
Author(s):  
Carlos Guardiola ◽  
Benjamín Pla ◽  
Pau Bares ◽  
Alvin Barbier
Keyword(s):  
Closed Loop ◽  
Combustion Engine ◽  
Fuel Combustion ◽  
Operating Conditions ◽  
Dual Fuel ◽  
Maximum Pressure ◽  
Cylinder Pressure ◽  
Pressure Derivative ◽  
Combustion Modes ◽  
Dual Fuel Combustion

This work presents a closed-loop combustion control concept using in-cylinder pressure as a feedback in a dual-fuel combustion engine. At low load, reactivity controlled compression ignition combustion was used while a diffusive dual-fuel combustion was performed at higher loads. The aim of the presented controller is to maintain the indicated mean effective pressure and the combustion phasing at a target value, and to keep the maximum pressure derivative under a limit to avoid engine damage in all the combustion modes by cyclically adapting the injection settings. Various tests were performed at steady-state conditions showing good abilities to fulfil the expected operating conditions but also to reject disturbances such as intake pressure or exhaust gas recirculation variations. Finally, the proposed control strategy was tested during a load transient resulting in a combustion switching-mode and the results exhibited the closed-loop potential for controlling such combustion concept.

scholarly journals Environmental safety management of urban building by regulation of formation process of exhaust gases of motor vehicles

2018 ◽  
Vol 196 ◽  
pp. 04065
Author(s):  
Liparit Badalyan ◽  
Vladimir Kurdjukov ◽  
Alla Ovcharenko
Keyword(s):  
Flow Rate ◽  
Combustion Engine ◽  
Operating Conditions ◽  
Pollutant Emissions ◽  
Motor Vehicles ◽  
Economic Losses ◽  
Reliable Determination ◽  
Exhaust Gases ◽  
Modern Development

Modern development of the construction industry involves accounting and assessment of operating conditions of structures. Excessive technological environmental impact can lead to economic losses and a decrease in the efficiency of investment projects in construction. Mobile sources emission record is an important component of the ecosystem state diagnosis in modern cities. For scientifically substantiated and reliable determination of the mass flow of the motor vehicles pollutants it is necessary to take into account the mixture formation and combustion of the working mixture in the internal combustion engine. The article describes the authors' approach to calculating the volumetric flow rate of exhaust gases based on the characteristics of the vehicle's transport operations available for operational control. Studies have shown that, when using a particular fuel, the determination of the volume flow rate of exhaust gases can be reduced to finding the power of the engine . In addition, the composition changes of the fuel (or fuel replacement) and the regulation of the effective power of the engine (by organization of traffic) allow to influence on the volume and composition of the emission of exhaust gases of vehicles and on the pollution of the urban environment in general. The results of the studies make it easier to calculate the mass of pollutant emissions by the transport stream into the outer air and can be used as preliminary data to assess the negative anthropogenic impact on the ecosystem.

Comparison of Crankangle Based Ignition Timing Methods on an HCCI Engine

2010 ◽  
Author(s):  
Ahmad Ghazimirsaied ◽  
Mahdi Shahbakhti ◽  
Charles Robert Koch
Keyword(s):  
Heat Release ◽  
Operating Conditions ◽  
Main Stage ◽  
Cyclic Variation ◽  
Ignition Timing ◽  
Crank Angle ◽  
Pressure Trace ◽  
Engine Operating Condition ◽  
Start Of Combustion ◽  
Third Derivative

Autoignition timing of a mixture in Homogeneous Charge Compression Ignition (HCCI) is very dependant and sensitive to the engine operating condition. To characterize combustion timing, different crank angle dependant methods are used but these methods can exhibit inaccurate results at some operating conditions. In this paper, a criterion that divides the engine operating condition into two regions, low and high cyclic variations (unstable operation) is defined. Then, different crankangle based methods for determining the start of combustion inside the cylinder for each of the two regions are compared. The start and duration of combustion are compared for wide range of operating conditions and the relative merits of each method discussed. The methods for characterizing the start of combustion are: CA50 based on the total heat release; the start of combustion from the third derivative of the pressure trace with respect to crank angle; the start of combustion from the third derivative of the pressure trace with respect to crank angle with two limits; CA10 based on total heat release; CA10 based on peak of main stage of combustion. The last method is introduced in this paper and has advantages in terms of accuracy of ignition timing detection and correlation with the start of combustion particularly for high cyclic variation engine operation. A new criterion, defined as the ratio between peak of main stage and the sum of peak of main stage and cool flame stage of heat release, is introduced to more accurately identify the operating region of the engine. This criterion is used to understand the performance of each of those crank angle based methods. The performance of each of those methods is investigated for both the low cyclic variation and the high cyclic variation (unstable) region of the engine.

Fuel-Air Ratio Determination From Cylinder Pressure Time Histories

1985 ◽  
Vol 107 (4) ◽  
pp. 252-257 ◽  
Author(s):  
J. C. Gilkey ◽  
J. D. Powell
Keyword(s):  
Time History ◽  
Operating Conditions ◽  
Cylinder Pressure ◽  
Pressure Time ◽  
Wide Range ◽  
Pressure Trace ◽  
Time Histories ◽  
High Bandwidth ◽  
Ratio Determination ◽  
Microprocessor Technology

Determining fuel-air ratio quickly over a wide range of engine operating conditions is desirable for better transient engine control. This paper describes a method based on cylinder pressure time history pattern recognition which has potential for providing such a high bandwidth measurement. The fact that fuel-air ratio has an effect on the shape of the cylinder pressure trace is well-known. It should therefore be possible to obtain the fuel-air ratio of an engine by examining the pressure trace if the engine speed, load, and EGR are known. The difficulty lies in separating the effects of unknown engine load, speed, and EGR from the fuel-air ratio effects. An algorithm was developed using a wide range of steady state experimental data from a single cylinder engine. Application of the algorithm requires the calculation of first, second and third moments of the cylinder pressure time history. Verification of the algorithm showed that the root mean square error in estimates were about 5 percent for fuel-air ratio and 3 percent for a combination of fuel-air and EGR. These results were obtained using a single pressure trace which yields a response time of 1.5 engine revolutions. The algorithm was also found to be relatively insensitive to the use of different fuels, errors in spark advance, and variations in relative humidity. Research is continuing to verify the accuracy under transient engine conditions. An operational count shows that this algorithm should be well within the limits of present microprocessor technology.

Deep learning procedure for knock, performance and emission prediction at steady-state condition of a gasoline engine

2020 ◽  
Vol 234 (14) ◽  
pp. 3347-3361
Author(s):  
Seunghyup Shin ◽  
Sangyul Lee ◽  
Minjae Kim ◽  
Jihwan Park ◽  
Kyoungdoug Min
Keyword(s):  
Deep Learning ◽  
Steady State ◽  
Gasoline Engine ◽  
Pressure Rise ◽  
Learning Model ◽  
Operating Conditions ◽  
Cylinder Pressure ◽  
Steady State Condition ◽  
Brake Mean Effective Pressure ◽  
Deep Learning Model

Recently, deep learning has played an important role in the rise of artificial intelligence, and its accuracy has gained recognition in various research fields. Although engine phenomena are very complicated, they can be predicted with high accuracy using deep learning because they are based on the fundamentals of physics and chemistry. In this research, models were built with deep neural networks for gasoline engine prediction. The model consists of two sub-models. The first predicts the knock occurrence, and the second predicts performance, combustion, and emissions. This includes maximum cylinder pressure, crank angle at maximum cylinder pressure, maximum pressure rise rate, and brake mean effective pressure, brake-specific fuel consumption, brake-specific nitrogen oxides, and brake-specific carbon oxide, which are representative results of the engine (for normal combustion cases without knock). Model input parameters were selected considering engine operating conditions, and physically measurable sensor values. For test cases, the accuracy of the first model for knock classification is 99.0%, and the coefficient of determination (R2) values for the second model are all above 0.99. Test times of both models were approximately 2 ms. The robustness of all the models was verified using K-fold cross-validation. A sensitivity study of accuracy, according to the amount of training utilized, was also conducted to determine how many data points are required to effectively train the deep learning model. Accordingly, a deep learning approach was applied to predict the steady-state conditions of a gasoline engine. Achieved model accuracies and robustness proved deep learning to be an effective modeling approach, and test time was recognized to be able to apply for the real-time prediction. The sensitivity analysis can be applied for the preliminary study to define the number of experimental points for the deep learning model.

Effects of λ on the Combustion Characteristics of HCCI Engine Fueled with N-Butanol

2015 ◽  
Vol 1092-1093 ◽  
pp. 508-511
Author(s):  
Jia Wang Zhou ◽  
Chun Hua Zhang ◽  
Gang Li ◽  
Ye Chun Shen
Keyword(s):  
Heat Release ◽  
Heat Release Rate ◽  
Release Rate ◽  
Combustion Engine ◽  
Pressure Rise ◽  
Combustion Characteristics ◽  
Cylinder Pressure ◽  
Maximum Heat ◽  
Hcci Engine ◽  
Combustion Duration

The combustion characteristics of an HCCI engine fueled with n-butanol were investigated on a modified two-cylinder, four stoke diesel engine. The experiments were conducted on the HCCI engine with λ of 2.0, 2.5 and 3.0, and the intake air temperature and engine speed were kept at 140 °C and 1000rpm, respectively. Effects of λ on combustion characteristics including in-cylinder pressure rise rate, heat release rate, CA05 and combustion duration of HCCI combustion engine are discussed in details based on the recorded in-cylinder pressure. The results indicate that in-cylinder pressure and the rate of pressure rise both decrease with the increase of λ, the maximum heat release rate also decreases with the increase of λ but occurs at late crank angles. In addition, as λ increases, the combustion phasing retards and combustion duration becomes longer.

An Experimental Study on Combustion and Performance of a Liquefied Natural Gas–Diesel Dual-Fuel Engine With Different Pilot Diesel Quantities

2019 ◽  
Vol 12 (2) ◽  
Author(s):  
Jiantong Song ◽  
Guna Wang
Keyword(s):  
Standard Deviation ◽  
Pressure Rise ◽  
Mean Value ◽  
Operating Conditions ◽  
Injection System ◽  
Dual Fuel ◽  
Cylinder Pressure ◽  
The Mean ◽  
And Performance ◽  
Injection Technology

Abstract The pilot diesel quantity (mpilot) has an impact on the liqueified nitrogen gas (LNG)-diesel dual-fuel engine, but it is very difficult for a dual-fuel engine with the traditional injection system to adjust mpilot to meet various operating conditions in practice. In recent years, with great progress in common rail diesel injection technology, mpilot can be adjusted accurately by the electronic control system, which is an advantage for operation with the diesel–LNG dual-fuel. In order to optimize mpilot of the diesel–LNG dual-fuel engine, the combustion and performance of a dual-fuel engine with the mpilot of 5.05 mg/cyc, 5.20 mg/cyc, 5.69 mg/cyc, 6.31 mg/cyc and 6.91 mg/cyc under 50% load at speed of 1600 r/min were analyzed. Experimental results show that, with an increase in mpilot, the maximum in-cylinder pressure, rate of pressure rise, and heat release rate of dual-fuel obviously increase, the crank angles of the maximum value move forward, and the combustion duration becomes shorter. The mean value of peak in-cylinder pressure (pmax) increases obviously while the standard deviation of it decreases, and the distribution of that focuses. The mean value of the crank angle corresponding to pmax pressure decreases except for the mpilot of 5.05 mg/cyc, while the standard deviation of that gradually decreases, the distribution of it focuses and moves forward. The brake power increases while the brake-specific fuel consumption (BSFC) decreases, the CO and HC decrease, while the CO2, NOx, and smoke density emissions increase.

Simulation and Contrast Analysis of tem Images of Cracks

1990 ◽  
Vol 48 (1) ◽  
pp. 578-579
Author(s):  
D. Goyal ◽  
A. H. King
Keyword(s):  
Displacement Vector ◽  
Crack Tip ◽  
Perfect Crystal ◽  
Operating Conditions ◽  
Displacement Fields ◽  
Fringe Contrast ◽  
Orthogonal Geometry ◽  
Moire Fringe ◽  
Moiré Fringe

TEM images of cracks have been found to give rise to a moiré fringe type of contrast. It is apparent that the moire fringe contrast is observed because of the presence of a fault in a perfect crystal, and is characteristic of the fault geometry and the diffracting conditions in the TEM. Various studies have reported that the moire fringe contrast observed due to the presence of a crack in an otherwise perfect crystal is distinctive of the mode of crack. This paper describes a technique to study the geometry and mode of the cracks by comparing the images they produce in the TEM because of the effect that their displacement fields have on the diffraction of electrons by the crystal (containing a crack) with the corresponding theoretical images. In order to formulate a means of matching experimental images with theoretical ones, displacement fields of dislocations present (if any) in the vicinity of the crack are not considered, only the effect of the displacement field of the crack is considered.The theoretical images are obtained using a computer program based on the two beam approximation of the dynamical theory of diffraction contrast for an imperfect crystal. The procedures for the determination of the various parameters involved in these computations have been well documented. There are three basic modes of crack. Preliminary studies were carried out considering the simplest form of crack geometries, i. e., mode I, II, III and the mixed modes, with orthogonal crack geometries. It was found that the contrast obtained from each mode is very distinct. The effect of variation of operating conditions such as diffracting vector (), the deviation parameter (ω), the electron beam direction () and the displacement vector were studied. It has been found that any small change in the above parameters can result in a drastic change in the contrast. The most important parameter for the matching of the theoretical and the experimental images was found to be the determination of the geometry of the crack under consideration. In order to be able to simulate the crack image shown in Figure 1, the crack geometry was modified from a orthogonal geometry to one with a crack tip inclined to the original crack front. The variation in the crack tip direction resulted in the variation of the displacement vector also. Figure 1 is a cross-sectional micrograph of a silicon wafer with a chromium film on top, showing a crack in the silicon.

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