Engineering Tuning Research Articles

Analysis of a chosen combustion parameters of dual fuel SI engine fuelled with alcohol and gasoline

The paper presents comparison of a selected combustion parameters of dual fuel, spark ignited engine run on gasoline and methyl alcohol. To the testing was used a four cylinder Fiat 1100 MPI engine with multipoint injection of gasoline and alcohol to area of inlet valve. Preliminary tests of the engine pointed at significant differences of its performance when the engine was run on alcohol only and on gasoline only [1]. In connection with it an indicator tests were performed in order to determine, on their base, a differences present in runs of combustions of the both fuels. The paper presents comparison of maximal pressure, rate of pressure rise, average temperature of working medium, heat release rate, total angle of combustion and indicated efficiency. These parameters were analyzed both in function of crankshaft rotation angle as well as engine load. Obtained results show at different course of methanol combustion comparing to gasoline. Run of methanol combustion is more rapid, what leads to growth of engine efficiency and increase of maximal cylinder pressures. Growth of working medium temperatures during combustion, what can lead to growth of thermal load of the engine, can be included to disadvantageous phenomena. Performed tests point at necessity of engine tuning modification during feeding with methanol, what would enable to take full benefits of advantageous properties of that fuel. Simultaneously, optimization tests have enabled to restrict disadvantageous effects of combustion of methanol.

大型ＤＭＥディーゼルエンジン発電システムの研究開発 －ＤＭＥ燃料による低環境負荷発電システムの実用化

DME is widely gaining acceptance as an alternative fuel for diesel engines. DME is a clean fuel that does not emit soot, PM, and SOx. It has a high cetane number, and is suitable for diesel engines. According to its exhaust characteristics, NOx reduction is easily attained by engine tuning and by applying a large amount of EGR. Focusing on these advantages, JFE Engineering and Daihatsu Diesel have jointly developed a DME diesel power generation system and constructed a 1250kW DME demonstration plant. Technical tests for various elements and continuous endurance tests were completed, and its potential for practical use was confirmed. This paper describes the outline of the world's first large-scale power generation DME plant, presents distinctive test results, and also describes the future of DME fuel.

Perturbation/correlation based optimal internal combustion engine tuning

This paper addresses the application of the perturbation/correlation method to optimizing the torque output of internal combustion engines. This application was inspired by observations of the limitations in current techniques of the automotive performance tuning industry. Performance issues such as errors from true optimum spark timing and fuel injector pulse width values as well as convergence were considered for optimal tuning. The ability of the system to deal with engine cycle-to-cycle variations and their effect on input parameters is also analyzed.

２ストローク低速ディーゼル機関の大幅ＮＯｘ低減技術

The outline of Tier 2 and Tier 3 NOx reduction regulations of IMO became clear at the meeting of MEPC57, which was held on this spring. Tier 2 can be achieved using conventional technologies; timing retard, engine tuning, electronically control of fuel injection and water technologies. However, Tier 3 will not allow such technologies, which are not able to achieve the future regulation line. The most closed technology is the after treatment system; SCR (Selective Catalytic NOx Reduction system) . SCR has some problem to install the vessels which are propelled by the 2-stroke cycle low speed diesel engines. The biggest problem is the low temperature of exhaust gas, which is under the 300 °C. In the atmosphere of the exhaust gas with Ammonium under the 300°C, it is generated the acid ammonium sulfate, which coated on the surface of catalyst and decrease the effectiveness of chemical reaction. In conventional trials of SCR on actual vessels, all SCRs were installed before turbochargers in order to avoid the low temperature exhaust gas. However, with SCR installed before turbocharger is not convenient for the partial load operation or coastwise services.

Heavy Metal Status and Oxidative Stress in Diesel Engine Tuning Workers of Central Indian Population

To assess the oxidative stress induced due to heavy metal exposure. Exposed populations are selected from an engine tuning station and control from the same area with no occupational exposure. Standard methods were followed for enzymatic assay, and heavy metals in blood and urine were analyzed by using inductively coupled plasma-optical emission spectrophotometer after microwave digestion. Changes in mean blood Pb, Cd, and Ni concentrations in blood and urine of exposed population of all age groups (20 to 35, 35 to 45, and 46 to 58 years) and exposure durations (< or =10, 11 to 20, and >20 years) were statistically not significant. However, exposed workers exhibited statistically significant higher antioxidant status in terms of serum glutathione-S-transferase activity, malondialdehyde level, and catalase activity. The findings in this article suggest that occupational exposure to diesel exhaust of engine tuning workers causes induction of oxidative stress, which cannot be correlated with the heavy metals status in blood and urine of an exposed population.

REDUCTION OF 3D MODELS FOR FAST AND RELIABLE SIMULATIONS OF COMBUSTION IN GDI ENGINES AT FULL LOAD

ABSTRACT The GDI process leads to combustion with lean mixtures which may lead to improved fuel economy and emissions relative to homogeneous spark ignition (SI) engines. To satisfy the different steps of operation, the tuning of GDI engines requires a model with a very short computation times to simulate the engines in the whole operating range and to reduce the number of engine tests which are time consuming and very expensive. Therefore the objective of this paper is to present a reduced model to analyze the combustion process in GDI engines, applied to a homogeneous stoichiometric mode. The objective of the model is to reproduce the same tendencies as those obtained by 3D models, but with a reduced computational time. The 1D model is obtained thanks to a reduction methodology based on the geometry of the combustion front computed with 3D models of the KIVA-II type. The results of the 1D model are compared to those obtained by the KIVA IIGSM under different engine conditions and to the measured pressure. The comparison shows that the 1D model overestimates the maximum cylinder pressure, which has an insignificant effect on the net indicated work per cycle. The results obtained by the 1D model are close to those given by the 3D model, with a much reduced computation time.

Time domain computational modeling of viscothermal acoustic propagation in catalytic converter substrates with porous walls

Models for viscothermal effects in catalytic converter substrates are developed for time domain computational methods. The models are suitable for use in one-dimensional approaches for the prediction of exhaust system performance (engine tuning characteristics) and radiated sound levels. Starting with the “low reduced frequency” equations for viscothermal acoustic propagation in capillary tubes, time domain submodels are developed for the frequency-dependent wall friction, frequency-dependent wall heat transfer, and porous wall effects exhibited by catalytic converter substrates. Results from a time domain computational approach employing these submodels are compared to available analytical solutions for the low reduced frequency equations. The computational results are shown to agree well with the analytical solutions for capillary geometries representative of automotive catalytic converter substrates.

NO2/NO emissions of gasoline passenger cars and light-duty trucks with Euro-2 emission standard

The total amount, as well as the partitioning, of the NOx emissions of six gasoline passenger cars and 10 light-duty trucks, all of Euro-2 emission standard, was measured in this study. The measurements were carried out in the NEDC and FTP75 cycles, in the German “Bundesautobahnzyklus” (federal motorway cycle) and in Swiss real-world cycles. All the vehicles were provided by private owners and brought directly from the road to the chassis dynamometer. In order to obtain results which are as realistic as possible, no servicing was carried out. Depending on their mass, gasoline light-duty trucks of the Euro-2 emission standard have a legal HC+NOx limit which is 20–40% higher than for gasoline passenger cars of the same generation. The measurements show that light-duty trucks emit about eight times more NOx in Swiss real-world cycles compared to passenger cars. However, this cannot be due to the higher engine load alone; there have to be major differences in engine construction, engine tuning or in the layout of the exhaust gas aftertreatment system. It can be observed that the overall catalyst efficiencies of light-duty trucks are substantially lower than those of passenger cars. Apart from this difference in total NOx emissions, an interesting difference in the partitioning of NO and NO2 for passenger cars and light-duty trucks can be observed. On average, about 5.3 mass-percent of the NOx emissions from the measured passenger cars are emitted as NO2, without a clear effect on the velocity pattern driven. In contrast to the behaviour of passenger cars, the measured light-duty trucks show a strong dependence on the velocity pattern. They emit on average 18.4 mass-percent NO2, but this figure goes up to 38.3 percent for motorway driving. The measurements show that the NO2 mass fraction depends strongly on the absolute NOx emission level: the more NOx is emitted, the higher is the NO2 mass fraction.

Modeling of Combustion in Gasoline Direct Injection Engines for the Optimization of Engine Management System Through Reduction of Three-Dimensional Models to (n × One-Dimensional) Models

Gasoline direct injection (GDI) spark ignition engines may be able to run over a wide range of operating conditions. The GDI process allows combustion with lean mixtures which may lead to improved fuel economy and emissions relative to homogeneous spark ignition (SI) engines. To satisfy the different modes of operation, the tuning of GDI engines requires a large number of engine tests which are time-consuming and very expensive. To reduce the number of tests, a model with a very short computational time to simulate the engines in the whole operating range is needed; therefore the objective of this paper is to present a reduced model to analyze the combustion process in GDI engines, applied to a homogeneous stoichiometric mode. The objective of the model is to reproduce the same tendencies as those obtained by three-dimensional models, but with a reduced computational time. The one-dimensional model is obtained thanks to a reduction methodology based on the geometry of the combustion front computed with three-dimensional models of the KIVA-GSM code, a modified version of KIVA-II code including a CFM combustion model. The model is a set of n one-dimensional equations (i.e., for n rays), taking into account a thin flame front, described with the flamelet assumption. It includes a CFM combustion model and a (k,ε)-model including the mean air motions (swirl and tumble). The results of the one-dimensional model are compared to those obtained by the KIVA IIGSM under different engine conditions. The comparison shows that the one-dimensional model overestimates the maximum cylinder pressure, which has an insignificant effect on the net indicated work per cycle. The results obtained by the numerical simulations are close to those given by the three-dimensional model, with a much reduced computation time.

Demonstration of environmentally sound and cost-effective shipping

This paper reviews improvement options for environmentally sound and cost-effective short sea shipping based on co-operation with shipping companies and shipyards. In operation, fuel can be saved by pre-treatment of bunker oil, proper tuning of engines and use of antifouling agents. Machine chamber waste can be reduced by quality control of lubricants and engine maintenance. Redesign of ships and use of gasoil instead of heavy oil, enables pollution reduction, a 40–45% fuel saving, reduction of acidification by 75–80%, no soot and less sludge. Less toxic antifouling and a watershaft instead of propulsion lubricant can be used at low extra cost. A dedicated trade makes it possible to reduce sailing speed and handling in harbours, which save fuel up to 20% and reduce waiting time in harbours. The improvements reduce the life cycle costs of ships but require more initial investment. Auditing, demonstration projects and policy instruments like tariff differentiation foster good environmental practices.

A new indicator for knock detection in gas SI engines

Determination of knock onset for any engine tuning remains a difficult work for many engine manufacturers. This study investigates different combinations of existing knock indices in order to produce an upgraded indicator, which is easier to calibrate. Experiments are conducted on a single-cylinder gas engine bounded to combined heat and power (CHP). Effects of spark advance, volumetric efficiency and equivalent ratio are studied under constant speed operation. The ratio IMPO/( MAPO× W) (with IMPO defined as the Integral of Modulus of Pressure Oscillations, MAPO as the Maximum Amplitude of Pressure Oscillations and W as the width of the computational window) is proposed as suitable indice. In any engine setting, it remains constant under no knocking conditions. When knock occurs, a model deduced from dimensionless analysis allows determination of the oversteps of Knock Limited Spark Advance from a single IMPO/( MAPO× W) measurement with an accuracy better than 1 CA. Knock is then studied for different gas qualities by adding propane or carbon dioxide to the fuel. The results show that there is no significant effect of the fuel composition on the proposed indicator, making the model able to calculate KLSA overstep in all the situations.

Automated tuning of an engine management unit for an automotive engine

Modern automotive engines are digitally controlled using an engine management unit (EMU) that is typically manually programmed using an engine dynamometer to obtain desired levels of power, emissions and efficiency. Closed-loop control of an engine dynamometer and EMU, combined with an overall engine tuning algorithm, is used to automate the tuning of the engine map for a four-cylinder engine. The tuning algorithm determines the air-to-fuel ratio necessary for each region of engine speed and throttle position to obtain the desired performance, automatically moving to each operating region in the map. Preliminary automated tuning results produce power output curves comparable with those delivered using the original manufacturer tuned EMU. At lower engine speeds data filtering is required and results in power outputs slightly lower than the factory-tuned engine. At higher speeds small improvements in engine efficiency, for equivalent performance, can be found. The research presented clearly demonstrates that engine tuning to a very high standard, equivalent to original equipment manufacturer engine performance, can he successfully automated, saving time and adding consistency to the engine tuning process.

Cfd Aided Development of a Si-Di Engine

Gasoline Direct Injection (GDI) appears to be the most relevant way to improve fuel efficiency of SI engines. But today, GDI is essentially regarded as a suitable technology for relatively high displacement engines, and the literature shows that the R&D effort on GDI engines is generally made for bores larger than 80 mm. For small bore engines (bore below 75 mm), locating an injector in already congested cylinder heads, with ultra lean stratified combustion capability while maintaining high engine specific power and proper cylinder head cooling is a real challenge. For such an engine, IFP is developing a 3-valve per cylinder engine (NSDI-3), based on a narrow spacingconcept, with a spark-plug-close-to-the-injector design and a suitable piston to confine the gasoline spray within the vicinity of the ignition location. This paper describes the contribution of 3D modeling to the development of this engine, from the initial work during the design of the prototype combustion chamber, to the development and tuning of the prototype engine on the test bench.

Advanced Gas Engine Cogeneration Technology for Special Applications

In recent years gas Otto-cycle engines have become common for various applications in the field of power and heat generation. Gas engines in gen-sets and cogeneration plants can be found in industrial sites, oil and gas field application, hospitals, public communities, etc., mainly in the U.S., Japan, and Europe, and with an increasing potential in the upcoming areas in the far east. Gas engines are chosen sometimes even to replace diesel engines, because of their clean exhaust emission characteristics and the ample availability of natural gas in the world. The Austrian Jenbacher Energie Systeme AG has been producing gas engines in the range of 300 to 1600 kW since 1960. The product program covers state-of-the-art natural gas engines as well as advanced applications for a wide range of alternative gas fuels with emission levels comparable to Low Emission (LEV) and Ultra Low Emission Vehicle (ULEV) standards. In recent times the demand for special cogeneration applications is rising. For example, a turnkey cogeneration power plant for a total 14.4 MW electric power and heat output consisting of four JMS616-GSNLC/B spark-fired gas engines specially tuned for high altitude operation has been delivered to the well-known European ski resort of Sestriere. Sestriere is situated in the Italian Alps at an altitude of more than 2000 m (approx. 6700 ft) above sea level. The engines feature a turbocharging system tuned to an ambient air pressure of only 80 kPa to provide an output and efficiency of each 1.6 MW and up to 40 percent @ 1500 rpm, respectively. The ever-increasing demand for lower pollutant emissions in the U.S. and some European countries initiates developments in new exhaust aftertreatment technologies. Thermal reactor and Selective Catalytic Reduction (SCR) systems are used to reduce tailpipe CO and NOx emissions of engines. Both SCR and thermal reactor technology will shift the engine tuning to achieve maximum efficiency and power output. Development results are presented, featuring the ultra low emission potential of biogas and natural gas engines with exhaust aftertreatment.

Calcul des émissions unitaires de polluants des véhicules utilitaires

To assess pollutant unit emissions for duty vehicles we combine engine emission maps with engine operating conditions as calculated by a vehicle simulation model. The SIVA model takes into account the vehicle characteristics (engine, transmission, etc.) including load, and the characteristics of the route taken (road gradients and curves, speed limits, stops). This model calculates instantaneous operating conditions, in particular the engine torque and speed which in turn enables the calculation of pollutant emissions. CO2, CO, HC, NOx and particulate emissions as well as fuel consumption were calculated for three duty vehicles, a small 3.5-tonnes duty vehicle, a 19-tonnes truck and a 40-tonnes semi-trailer truck. Simulated operating conditions corresponded to highway (a 65-km trip), main road (a 93-km trip) and steady vehicle speed conditions for various values of road gradient from −4% to +6%. Results show the significant influence of vehicle mass on fuel consumption and pollutant emissions, engine technology (injection, aspiration), engine tuning (legislation, regulation), vehicle speed and road gradient. Collecting data on pollutant emissions and data on operating conditions in actual vehicle use are thus of great interest.

Development of a Thermodynamic Method for Diagnosis and Tuning of Diesel Engines And its Application on Marine Engines

In the present paper a method is proposed for fault diagnosis and correct tuning of diesel engines. It is based on a thermodynamic simulation model of the engine and its components: the fuel injection system, the turbocharger and the air cooler. The method requires the experimental cylinder and fuel injection system pressure diagrams and operational data of the various engine sub-systems, air cooler, turbocharger, etc. It is known that it is very difficult to measure the TDC (top dead centre) on commercial engines. In order to overcome this difficulty the TDC is determined via a thermodynamic method introduced and verified by the present research group. In this paper an application of the proposed method on a low-speed two-stroke marine diesel engine is presented. The results obtained reveal the present condition of the engine and its sub-systems while a comparison between calculated and experimental results reveals the accuracy of the simulation model used.

The potential of methanol and LPG as new fuels for transportation

The energy supply situation grows more and more critical. Alternatives to presently used fuels are necessary, mainly for road transport. Alcohol fuels, mainly methanol and Liquified Petroleum Gas (LPG) offer the possibility for use in engines with high thermal efficiency. The necessary modifications with regard to present gasoline engines are discussed. Results from engine tuning and vehicle tests are reported. Both fuels have advantages over present gasoline engines if the engine—vehicle concept is optimized for these fuels. Thermal efficiency and power output increase while exhaust emissions are lower. These results offer a basis for decisions how future energy questions can be resolved depending on economic, political and technical factors.

Paper 8: Engine Tuning to Minimize Exhaust Emissions

With the minimum amount of time available to satisfy impending pollution regulations, a hurried programme of engine research and development was embarked upon to reduce emissions by the simplest and quickest means. Early attempts with air injection methods had shown promising results, but installation problems resulted in efforts directed towards an engine tuning approach. With lean set carburation and retarded ignition, tests showed that emission levels could be reached which were within striking distance of the proposed limits. Analysis of the various modes of operation showed that deceleration peaks, and in the case of manual transmissions, gear change peaks, were highly contributing factors. A simple type poppet valve incorporated in the throttle plate of the carburettor, and set to operate at a given manifold depression, considerably reduced emissions during deceleration and gear change, bringing composite values within the prescribed limits. Further development of the valve was undertaken and is described in the text. The development of systems involved investigation into carburettor metering, mixture preparation, ignition timing, temperature compensation, throttle damping, and fuel cut-off.

Paper 13: Exhaust Emissions of Vehicles Tested to the Draft European Procedure

The work in this report was prompted by the probability of legislation in most European countries to limit the emission of carbon monoxide and possibly unburnt hydrocarbons from the exhausts of petrol-engined vehicles. A draft method of testing has already been agreed upon and this work was carried out in accordance with this draft procedure. The object of the work was to establish the baseline emissions of vehicles currently in service in Great Britain and, to achieve this, approximately 100 cars, representative of the age and engine capacity distribution of the population of Great Britain, were tested. The full test procedure consists of four cycles of a specified speed–time relationship driven from cold in which the exhaust gas is collected in bags for subsequent measurement of gas volume and carbon monoxide and hydrocarbon concentrations. For greater convenience, most tests were run from the hot condition and corrections applied to give the equivalent cold start data. These corrections, obtained by comparison of emissions from hot and cold start tests, were factors of 1·05 for mass and 0·95 for concentration. The results of tests indicated that the average emission of carbon monoxide for cars in service in Great Britain is 172 g for the four cycles of the test procedure from a cold start, which is equivalent to a concentration of 3·4 per cent; the range of emissions is from 0·60 to 7·36 per cent. Although considered of less importance in Europe, hydrocarbons were also measured and gave an average emission of 11·0 g from a cold start. Simple engine maintenance, such as corrections of ignition faults and carburettor maladjustments, was carried out on about half of the vehicles tested; these vehicles were representative of the sample as a whole and the maintenance resulted in a 20 per cent reduction in average carbon monoxide mass emissions and 10 per cent reduction in average hydrocarbon emissions. Idle emission measurements were carried out with the vehicles hot. These varied from 0·2 to over 11·6 per cent carbon monoxide, with an average level of 6·1 per cent. The average hydrocarbon emission was 1550 p.p.m. Engine tuning reduced the average idle carbon monoxide and hydrocarbon emissions by 29 and 40 per cent respectively. The idle setting was found to have a marked effect on emissions over the cycle, probably because of the large percentage of time in the cycle which is at very light throttle opening or closed. Some comparisons were also made between the results in relation to the U.S. Federal and proposed European test methods, but results were too scattered to warrant firm conclusions.