Spark Advance Real-Time Optimization Based on Combustion Analysis

Transient Spark Advance Calibration Approach

<div class="section abstract"><div class="htmlview paragraph">Water Injection (WI) has become a key technology for increasing combustion efficiency in modern GDI turbocharged engines. In fact, the addition of water mitigates significantly the occurrence of knock, reduces exhaust gas temperatures, and opens the possibility to reach optimum heat release phasing even at high load.</div><div class="htmlview paragraph">This work presents the latest development of a model-based WI controller, and its experimental validation on a GDI TC engine. The controller is based on a novel approach that involves an analytic combustion model to define the spark advance (SA) required to reach a combustion phase target, considering injected water mass effects. The calibration and experimental validation of the proposed controller is shown in detail in the paper. At first, the focus is on the open-loop branch, to evaluate the performance of the combustion model and its ability to manage Spark Advance (SA) taking in account the phasing implications of WI, maintaining a pre-defined combustion phase target. Then the closed-loop (CL) chain is introduced, defining a structure that allows reaching the target while keeping knock intensity (KI) levels under an established threshold using two different control levers (SA and WI). At the same time, the controller has been designed to minimize water consumption. The proposed controller has then been implemented in a Rapid Control Prototyping environment, to validate the strategy on a real engine. As shown in the paper, this approach allows to manage both combustion phasing and knock level in an engine equipped with WI.</div><div class="htmlview paragraph">The closed-loop controller was initially based on in-cylinder pressure signals both for knock intensity and combustion phasing measurements. To allow the proposed controller to be ready for an on-board implementation, there is the need to replace the pressure signal used from the in-cylinder pressure sensor, not available on commercial vehicles. For this, a specific signal processing algorithm has been developed to extract the angular combustion phase from the accelerometric signals available on-board, and it has been validated with experimental data.</div></div>

Taguchi-Grey Relational Based Multi-Objective Optimization Of Process Parameters On The Emission And Fuel Consumption Characteristics Of A VCR Petrol Engine

<div class="section abstract"><div class="htmlview paragraph">In the present work, an Auto Regressive Moving Average (ARMA) model and a Discrete Wavelet Transform (DWT) are applied on vibrational signals, acquired by an accelerometer placed on the cylinder block of a Spark Ignition (SI) engine, for knock detection purposes. To the aim of tuning such procedures, the same analysis has been carried out by using the traditional MAPO (Maximum Amplitude of Pressure Oscillations) index and an Inverse Kinetic Model (IKM), both applied on the in-cylinder pressure signals. Vibrational and in-cylinder pressure signals have been collected on a four cylinder, four stroke engine, for different engine speeds, load conditions and spark advances. The results of the two vibrational based methods are compared and in depth discussed to the aim of highlighting the pros and cons of each methodology. The presented outcomes show the capability of the vibration based detection algorithms in accurately monitor the presence of knock phenomena, and to determine its intensity according to the IKM and MAPO based methods. The comparison with a standard processing of the knock sensor output reveals the higher sensitivity of the proposed methodologies. Therefore, the possibility of implementation in modern on-board control units is foreseen, as well.</div></div>

Calorific value enhancement of fusel oil by moisture removal and its effect on the performance and combustion of a spark ignition engine

Experimental study of the composition of hydrogen enriched compressed natural gas on engine performance, combustion and emission characteristics

Increasingly stringent exhaust emission limits and higher fuel economy are the main drivers of the engine development process. As a consequence, the complexity of the propulsion units and its subsystems increase, due to the extensive use of sensors and actuators needed to obtain a precise control over the combustion phase. Since engine calibration process consumes most of the development time, new tools and methodologies are needed to shorten the development time and increase the performance attainable. Real time combustion analysis, based on the in-cylinder pressure signal, can significantly improve the calibration of the engine control strategies and the development of new algorithms, giving instantaneous feedback on the engine behavior. A complete combustion analysis and diagnosis system has been developed, capable of evaluating the most important indicators about the combustion process, such as indicated mean effective pressure, heat release, mass fraction burned and knock indexes. Such a tool is built on top of a flexible, modular and affordable hardware platform, capable of satisfying the requirements needed for accuracy and precision, but also enabling the use directly on-board the vehicle, due to its small form factor.

Homogenous charge compression ignition (HCCI) combustion is a low temperature combustion process which combines high combustion efficiency with ultra-low [Formula: see text] raw emissions. Steep increases of the in-cylinder pressure and unstable combustion sequences at the limits of the operating range can damage the engine and limit the use of HCCI to part load operation. This can be done using closed loop combustion control based on combustion parameters like the indicated mean effective pressure and the combustion phasing. Since in-cylinder pressure sensors are expensive components and therefore not suitable for series application, ion current sensors can be used as an additional source of information about the combustion. Combustion analysis using methods similar to those used in pressure based measurements can be implemented using an online analysis of the ion current signal. In this study, the ion current sensor will be examined for its suitability for combustion control under HCCI conditions with lean air/fuel ratios and high compression ratios. Research has found that the ion current signal is strongly depended on the boundary conditions. Especially the air/fuel ratio which plays an important role for signal strength during the combustion process. When using valve timings with negative valve overlap in combination with a fuel pre-injection, a further peak of the ion current signal close to the gas exchange top dead center can be found in addition to the one during combustion. At the same time, it is hard to extract information from the cylinder pressure signal during NVO. Under lean conditions this peak even exceeds the signal during combustion. This study analyzes the ion current signal during NVO and its potential to be used for future combustion control concepts. The ion current signal shows potential to stabilize HCCI combustion at high loads. However, the prediction of late combustion cycles is still challenging.

<div class="section abstract"><div class="htmlview paragraph">Engine downsizing is gaining popularity in the high performance engine market sector, where a new generation of highly downsized engines with specific power outputs around or above 150 HP/litre is emerging. High-boost and downsizing, adopted to increase power density and reduce fuel consumption, have to face the increased risks of pre-ignition, knock or mega-knock. To counterbalance autoignition of fuel/air mixture, such engines usually operate with high fuel enrichments and delayed (sometimes negative) spark advances. The former is responsible for high fuel consumption levels, while the latter reduces performance and induces an even lower A/F ratio (below 11), to limit the turbine inlet temperature, with huge negative effects on BSFC. A relatively simple yet effective solution to increase knock resistance is investigated by means of 3-D CFD analyses in the paper: water is port injected to replace mixture enrichment while preserving, if not improving, indicated mean effective pressure and knock safety margins. Full-load engine operations of a currently made turbocharged GDI engine are investigated comparing the adopted fuel-only rich mixture with stoichiometric mixtures, for which water is added in the intake port under constant charge cooling in the combustion chamber. In order to find the optimum fuel/water balance, preliminary analyses are carried out using a chemical reactor to evaluate the effects of charge dilution and mixture modification on both autoignition delays and laminar flame speeds. Thanks to the lower chemical reactivity of the diluted end gases, the water-injected engine allows the Spark Advance (SA) to be increased; as a consequence, engine power target is met, or even crossed, with a simultaneous relevant reduction of fuel consumption.</div></div>

Experimental Study on Performance, Combustion and Emissions of Diesel Engine with Re-entrant Combustion Chamber of Aluminum Alloy

Spark advance self-optimization with knock probability threshold for lean-burn operation mode of SI engine

In this work, PFI SI engine is modified into dual fuel mode and a mixture of 80% gasoline, 10% ethanol and 10% methanol is mixed and sent into the engine along with hydrogen gas at 0.l pm, 3.l pm, 9.l pm and 15.l pm. The engine was operated at a constant load of 5kg by varying speed from 1800 to 3400 rpm with 400 rpm intervals and the engine parameters like combustion, cylinder pressure (CP), net heat release rate (NHRR), rate of pressure rise (RoPR), performance like brake thermal efficiency (BTE), brake specific fuel consumption (BSFC) and volumetric efficiency, emissions like carbon monoxide (CO), hydrocarbons (HC), nitrogen oxide (NOx) and vibrations are studied and the results are good in agreement with gasoline, ethanol and methanol (GEM) blend with 15 l pm hydrogen flow rates. CP, NHRR, RoPR, BTE and volumetric efficiency increased by 33.73%, 54.25%, 27.65%, 9.88% and 7.49% and BSFC, CO, HC and NOx decreased by 31.25%, 71.66%, 55.95% and 4.02% respectively.

<div class="section abstract"><div class="htmlview paragraph">This paper presents the results of an experimental analysis on a multi-cylinder diesel engine, in which in-cylinder pressure and accelerometer transducers are used with the purpose of developing and setting up a methodology able to monitor and optimize the combustion behavior by means of non-intrusive measurements.</div> <div class="htmlview paragraph">Previously published results have demonstrated the direct relationship existing between in-cylinder pressure and engine block vibration signals, as well as the sensitivity of the engine surface vibration to variation of injection parameters when the accelerometer is placed in sensitive location of the engine block. Moreover, the accelerometer trace has revealed to be able to locate in the crank-angle domain important phenomena characterizing the combustion process (the start of pre-mixed combustion, the crank angle value corresponding to the beginning of diffusive combustion and to the in-cylinder pressure maximum value).</div> <div class="htmlview paragraph">The objective of the present work is to quantify the strict relationship between the in-cylinder pressure signal and the accelerometer trace, in order to obtain information concerning both the pressure maximum value and the pressure rise rate from the accelerometer trace.</div> <div class="htmlview paragraph">In this paper, the previously developed steps of the research program are briefly presented. The processing technique is described and representative results are presented and discussed, in which different values of speed and load have been imposed on the engine.</div></div>

Biodiesel is an alternative, eco-friendly and renewable source of energy. It can be produced from a wide range of feedstocks which can be grown in marginal land use. It has drawn more attention to the researchers. In this study, the oil extraction, biodiesel conversion, and physiochemical properties of Macadamia (Macadamia integrifolia) and Grapeseed (Vitis vinifera) biodiesels are presented. The experimental investigation of diesel engine performance, emissions and combustion characteristics were conducted using B5 (5% biodiesel and 95% diesel by volume) and B10 (10% biodiesel and 90% diesel by volume) blends. The engine performance parameters, such as brake power (BP), brake specific fuel consumption (BSFC), and brake thermal efficiency (BTE) have been investigated in this experiment. The emission parameters, for example, carbon monoxide (CO), the ratio of CO2/CO, nitrogen oxide (NOx), hydrocarbon (HC), particulate matter (PM) have been measured during the experiment. Finally, the combustion parameters such as cylinder pressure (CP) were recorded, and heat release rate (HRR) was analysed and compared with that of diesel fuel. The study revealed that the Macadamia biodiesel performed better than Grapeseed biodiesel and behaved closely to that of diesel fuel. A significant reduction of engine emissions was found in the case of Macadamia biodiesel with a minimal reduction of engine performance. Further analysis of energy, exergy and tribological characteristics of the Macadamia biodiesel is recommended for assessing its feasibility for commercial application.

<div class="htmlview paragraph">Performance and fuel consumption of a single-cylinder, direct-injection diesel engine were determined for both an untreated diesel fuel and for the same fuel treated with a platinum-based fuel additive package. The platinum was in an organometallic compound which was soluble and stable in diesel fuel. The fuel additive package was supplied by Fuel Tech, Inc., of Stamford, Connecticut. The engine, a Cooperative Lubrication Research (CLR) engine, was operated for 185 hours on untreated fuel (a low sulfur no. 2 diesel fuel), 236 hours on treated fuel and then 217 hours on the untreated fuel. Engine operating conditions were varied among three steady-state operating conditions at moderate load at 1300, 1600 and 1900 RPM.</div> <div class="htmlview paragraph">At the end of the 236 hours in which the additive treated fuel was used, the average brake specific fuel consumption (BSFC) decreased by approximately 9% at 1300 RPM, 5% at 1600 RPM, and negligibly at 1900 RPM. To understand the causes of the BSFC improvements, cylinder pressures were compared for the same conditions. This examination revealed that the cylinder pressures throughout portions of the compression and expansion stroke were higher after the additive was used. The lower BSFC values were attributed to increased indicated work due to shorter ignition delay periods and slightly greater instantaneous heat release rates during portions of the expansion stroke.</div>