Automotive Diesel Engine Research Articles

Heat release analysis of gasoline fumigation in a diesel engine

The aim of this study is to investigate experimentally gasoline fumigation (GF) and to apply heat release (HRR) analysis for two different compression ratios (CRs) for different gasoline fumigation ratios (GFs) at two engine speeds in an automotive diesel engine. Here, gasoline at 5–20 % (by vol.) ratios was injected in to intake air by using an adapted carburetor. Firstly, GF tests were conducted for original CR (18.25, high compression ratio, HCR) of the engine. Then, CR of the engine was reduced to 17 (low compression ratio, LCR) by changing of cylinder head gasket thickness and GF were also investigated for LCR. In this study, HRR was analyzed by using measured cylinder pressure values. At the end of the experimental study; it was seen that GF creates two peaks in HRR curve for selected all of the operating conditions. The first peak occurs before top dead center (TDC) and the second peak occurs after TDC. The first peak becomes larger and second peak decreases with increasing GFs. This indicates that combustion process is better than that of neat diesel fuel (NDF), especially for low GF ratios. In addition, GF increases cylinder pressure and temperature.

Experimental investigation of gasoline fumigation for different compression ratios in a diesel engine

In this study, the effects of gasoline injection into intake air (gasoline fumigation, GF) on the brake specific fuel consumption (bsfc), combustion characteristics such as excess air coefficient and exhaust temperature (Tex), nitrogen oxides (NOx) and opacity were experimentally investigated in an automotive diesel engine. One of the main objectives of this study is to experimentally investigate the effects of GF at the same engine for different compression ratios (CRs). The original CR of the engine is 18.25 (high CR, HCR). Here, CR of the engine was changed to 17 (low CR, LCR) by changing the cylinder head gasket thickness. Thus, experiments were performed for two different CRs such as 18.25 and 17 under five different loads such as 150, 135, 120, 105, and 90 Nm at 2000 rpm and under five different load such as 120, 105, 90, 75, and 60 Nm at 4000 rpm for various gasoline fumigation ratios (GFs). In this study; approximately 5, 10, 15 and 20 %, (by vol.) gasoline was injected into intake air by using an adapted carburetor. The test results showed that GF decreases bsfc for all of the working conditions. NOx emissions decrease with GF for high CR at 2000 rpm, but it generally increases for low CR (17) under high loads. NOx emissions increase significantly with GF for both CRs at 4000 rpm. Opacity decreases at low GFs, but it increases at high GFs. In general, the results of GF at the original CR (HCR) are better than the LCR. However, in the present study, no arrangement has been made in the electronic control unit (ECU) of the engine for changed CR.

Optimization of automotive diesel engine calibration using genetic algorithm techniques

Although the advancements in automotive diesel engines in the last two decades have resulted in the possibility of achieving better performance with lower pollutant emissions and fuel consumption, the increased complexity of the system and the high number of control parameters require the solution of optimization problems of high dimensionality. It is of crucial importance to identify suitable methodologies, which allow achieving the full exploitation of the potential of these powertrains. In this paper, an original methodology for optimizing the latest generation of common rail automotive diesel engines has been presented.Random optimization methods along with surrogate models were firstly used to generate a population of engine calibrations, which then served as an initial population to a specifically conceived Genetic Algorithm (GA) based optimizer, which was finally applied on a real data set for a particular engine operating point. The results were compared with a calibration optimized using a traditional local approach method. A simultaneous reduction of about 20% in NOX and 1% in Brake Specific Fuel Consumption was achieved, with no significant increase in other emissions. The methodology described in the paper has the potential to reduce the calibration time and effort by half, while obtaining better calibrations.

A physics-based turbocharger model for automotive diesel engine control applications

Control-oriented models of turbocharger processes such as the compressor mass flow rate, the compressor power, and the variable geometry turbine power are presented. In a departure from approaches that rely on ad hoc empirical relationships and/or supplier provided performance maps, models based on turbomachinery physics and known geometries are attempted. The compressor power model is developed using Euler’s equations of turbomachinery, where the gas velocity exiting the rotor is estimated from an empirically identified correlation for the ratio between the radial and tangential components of the gas velocity. The compressor mass flow rate is modeled based on mass conservation, by approximating the compressor as an adiabatic converging-diverging nozzle with compressible fluid driven by external work input from the compressor wheel. The variable geometry turbine power is developed with Euler’s equations, where the turbine exit swirl and the gas acceleration in the vaneless space are neglected. The gas flow direction into the turbine rotor is assumed to align with the orientation of the variable geometry turbine vane. The gas exit velocity is calculated, similar to the compressor, based on an empirical model for the ratio between the turbine rotor inlet and exit velocities. A power loss model is also proposed that allows proper accounting of power transfer between the turbine and compressor. Model validation against experimental data is presented.

Experimental Investigation of the Loading Strategy of an Automotive Diesel Engine under Transient Operation Conditions

Targeting the performance optimization of an automotive diesel engine under transient operation conditions, in this research, the effect of several non-linear loading strategies on diesel performance have been experimentally analyzed using a heavy-duty turbocharged diesel engine running under transient conditions based on the constant 1650 r/min speed, the load is increased from 10% to 100% in a 5 s transition time The results show that the larger the early loading rate and change point load, the better the dynamic torque response. The peak values of smoke and CO and the transient average of brake specific fuel consumption (BSFC), soot and CO can be decreased by increasing the early loading rate by the loading strategies with the appropriate change point load during transient operation. However, combustion deteriorates under the loading process with an overlarge change point load, causing emissions to increase, and the larger the early loading rate, the worse the worsening. Based on the trade-off consisting of torque dynamic response, transient total and transient average of the BSFC and brake specific emissions, peak values of smoke and CO emissions, it is concluded that the loading strategy with the early loading rate is the 50% load per second and the change point load in the 25% load is the most suitable in these strategies.

Selection of accelerated test modes for the head of cylinder of the automobile diesel engine

The possibilities of a prediction of the heads of cylinder durability of the automotive diesel engines at the design stage and their completion to specified parameters, especially for reliability are considered. Since diesel engines operate in the unsteady modes, the main load is not only mechanical, but also thermal. At that, it occurs when the operating modes of the diesel engine change. The most loaded sections in the cylinder head are the bridges between the inlet and exhaust valves, as well as the bridges between the nozzle holes and inlet and exhaust valves. Under the influence of the thermal load, the distortions of the crystal lattice appear in the sections of the cylinder head at first, which leads to the appearance in some direction in which the greatest tangential stresses act, tears, gradually change under the influence of alternating stresses in the crack. When the total accumulated damage reaches a certain critical value, and the crack substantially weakens the cross section, fatigue failure occurs. To ensure the reliability of the diesel engine in operation, it is necessary to choose such methods of calculation and testing that would ensure a specified durability of the cylinder head. Since the reliability check in operation takes considerable time, that accelerated testing is used to reduce the test time. The place occupied by the accelerated tests in the design of diesel engines, as well as the sequence of the formation of their program are considered. It is shown that in practice it is possible to achieve only a certain degree of change in the technical condition of the cylinder head due to the degree of completeness of the accounting of the interacting operational loads and their distortion during reproduced on the test equipment. Possible modes of testing the cylinder heads on a non-motorized thermal bench are proposed with the aim of a determination their durability. They correspond to the modes of accelerated tests for the reliability of the automobile diesel engines. The problem of convergence of the results at accelerated tests and the data under operating conditions is considered.

Comparison of Single and Multiple Injection Strategies in a Butanol Diesel Dual Fuel Engine

A turbocharged three cylinder automotive common rail diesel engine was modified to operate in the n-butanol diesel dual fuel mode. The quantity of butanol injected by the port fuel injectors and the rail pressure, injection timing, and number of injection pulses of diesel were varied using open engine controllers. Experiments were performed in the dual fuel mode at a constant speed of 1800 rpm at varying brake mean effective pressure (BMEPs). Butanol to diesel energy share was varied, and the injection timing of diesel was always set for highest brake thermal efficiency (BTE). Single pulse injection (SPI) and two pulse injection (TPI) of diesel were evaluated. In SPI, with increase in the butanol to diesel energy share, the BTE remained unchanged. At high loads and high amounts of butanol, the heat release rate (HRR) variation indicated that butanol auto ignited before diesel with both SPI and TPI of diesel. NO emission always decreased because of reduced temperatures due to evaporation of butanol. Butanol also reduced the smoke levels except at high loads. HC levels were always higher. With optimized injection parameters, TPI of diesel resulted in lower NO, similar smoke, and BTE with lesser rate of pressure rise as compared to SPI of diesel in the dual fuel mode at high loads. On the whole, the SPI mode is suitable for low to medium outputs and the TPI mode is suitable for high outputs.

Analysis of low-pressure exhaust gases recirculation transport and control in transient operation of automotive diesel engines

The objective of the study is to determine the behavior of the low pressure exhaust gas recirculation (LP EGR) transport phenomena in the intake manifold during engine transient operation. The investigation also analyzes the influence of the propagation of the pressure waves in the intake manifold on the engine performance. In this sense, there is a clear trade-off: long intake lines improve the engine volumetric efficiency at low engine speeds but delay the EGR transport in the system.The experiments were performed on a test bench with a 1.6 L Euro-5 specification diesel engine. A CO2 fast tracking measurement device was setup and placed in two locations in the intake line in order to track the EGR transport in transient operation. The CO2 concentration is acquired with crank-angle resolution. Three different engine transients at constant engine speed were studied. They are extreme and worst-case scenarios in driving situations: (i) from low load to full load, (ii) from full load to low load, and (iii) from low load to medium load. In this way, it is possible to observe the behavior of the engine when: (i) leaving the EGR zone, (ii) entering into the EGR zone, and (iii) changing operating point without leaving the EGR zone.A consistent methodology that combines experimental results and a 1D model capable to predict the behavior of the engine was developed. The results obtained in this investigation show a relevant phenomenon: depending on the synchronization of the EGR and Exhaust Throttle (ET) valves, an overshoot occurs when the engine enters into EGR zone. In this study, the results show the importance of the synchronization of the valves that control the EGR strategy. Comparisons between measured and modeled CO2 concentrations lead to conclude that the EGR transport during engine transient operation is correctly predicted within a 1D engine code.

Impact of hydrocracked diesel fuel and Hydrotreated Vegetable Oil blends on the fuel consumption of automotive diesel engines

The present paper describes the results of a research activity aimed to assess the potential of hydrocracked fossil oil (HCK) and Hydrotreated Vegetable Oil (HVO) blends, as future premium diesel fuels, on fuel consumption (FC) reduction of the modern automotive diesel engines.Three fuels have been formulated and tested in a light duty four-cylinder diesel engine, Euro 5 version, equipped with closed loop control of the combustion. The set of fuels comprised three experimental fuels formulated ad hoc by blending HVO and HCK streams, and an EN590-compliant commercial diesel fuel representative of the current market fuel quality.A specific test procedure based on a sequence of New European Driving Cycle (NEDC) and ARTEMIS cycles on an engine dyno test bed was applied in order to carry out accurate fuel consumption measurements versus fuel quality, so reproducing the fuel effects on FC for long mileage use of the vehicle.Results of the experimental activity proved that HCK-HVO blends give a benefit on both FC and CO2 saving. Taking into account the strong similarity in terms of combustion system design between Euro 5 and Euro 6 engines, the estimated trends can be considered valid also for Euro 6 vehicles equipped with the same class of engines. In a next step, it is planned to validate these results by carrying out also WLTP and RDE emission tests.

Influence on Performance and Emissions of an Automotive Diesel Engine Fueled with Biodiesel and Paraffinic Fuels: GTL and Biojet Fuel Farnesane

The effects of a paraffinic biofuel (farnesane) obtained from sugar cane, a gas to liquid (GTL) fuel, and a biodiesel fuel on performance and emissions of a light duty engine were evaluated. Similar engine performance is obtained with all fuels maintaining the default electronic control unit (ECU) configuration. Clear reductions in total hydrocarbon (THC) emissions were observed with all alternative fuels, and, comparing both paraffinic fuels, farnesane was more beneficial. Reductions were also obtained with these fuels in particle emissions, with the exception of the mode G, which is not an operating mode included in the New European Driving Cycle (NEDC), where particle number concentration of paraffinic fuels was higher compared with diesel and biodiesel fuels. This behavior could be explained by the nonoptimization of ECU at this engine work condition. The benefits in terms of pollutant emission obtained with farnesane make it a potential biofuel for use in diesel engines.

Characterisation of the corrosion fatigue behaviour of brazed AISI 304L/BNi-2 joints in synthetic exhaust gas condensate

Exhaust gas recirculation (EGR) with brazed heat exchangers is commonly used for the reduction of NOx emissions of automotive diesel engines. Since the fatigue loading of brazed EGR coolers during the operation is superimposed by corrosive attack due to aggressive exhaust gases, the corrosion fatigue behaviour of brazed joints is relevant for the component design. In the present study, brazed AISI 304L/BNi-2 joints were cyclically tested in the synthetic exhaust gas condensate K2.2, using a corrosion cell, as well as in air after pre-corrosion acc. to VDA 230–214 with ageing durations of up to 6 weeks. A significant reduction of the fatigue strength at 2 × 106 cycles down to 43% was determined for superimposed and down to 22% for successive corrosion fatigue loading. A galvanostatic anodic polarisation of the specimens tested in situ was applied successfully for an efficient reproduction of the corrosion fatigue behaviour after the long-time and cost-intensive pre-corrosion. In this context, a novel test strategy with local strain measurements, using a newly developed extensometer, as well as electrical and electrochemical measurements was established for a precise corrosion fatigue assessment of the brazed joints. Microstructure-related corrosion fatigue damage mechanisms were evaluated using scanning electron microscopy.

Benefits of E85 versus gasoline as low reactivity fuel for an automotive diesel engine operating in reactivity controlled compression ignition combustion mode

This work shows the capabilities of E85 fuel to be used as low reactivity fuel in a high compression ratio light-duty diesel engine (17.1:1) running under reactivity controlled compression ignition concept. To do this, experimental steady-state engine maps are obtained in a single-cylinder engine with diesel-E85 fuel combination. The engine mapping was performed following the same procedure used in previous works with other fuel combinations to allow the results comparison. Considering the mechanical and emissions limits imposed during the engine mapping, it was found that with diesel-E85 the combustion concept is limited to the region defined from 2 to 7 bar at 1000 rpm, and from 1.5 to 9 bar indicated mean effective pressure at 3000 rpm. This operating region was satisfied with nitrogen oxides, soot and pressure rise rate levels below 0.4 g/kWh, 0.01 g/kWh and 10 bar/CAD, respectively. The reactivity controlled compression ignition maps with diesel-E85 were obtained taking as reference the total fuel energy used in a previous work to map the engine with diesel-gasoline. The direct comparison of both combustion concepts (diesel-E85 and diesel-gasoline) revealed that E85 allows to extend the engine map around 2 bar indicated mean effective pressure towards the high load region. Moreover, the minimum load achieved at high engine speeds was decreased down to 1.5 indicated mean effective pressure. Finally, the differences in terms of emissions and performance between both reactivity controlled compression ignition concepts are highlighted by doing the difference between the maps of several variables.

Experimental analysis of the influence of coolant and oil temperature on combustion and emissions in an automotive diesel engine

Since many trips are of short duration and include a cold start, automotive engines run quite often without having reached their nominal temperature. This is known to have some major drawbacks, such as increased fuel consumption and higher emissions due to lower efficiency of after-treatment devices, but detailed description of these various effects is seldom presented in the literature. In this article, experiments were conducted on an automotive diesel engine by varying independently the coolant and oil temperatures between 30 °C and 90 °C. Three different operating conditions (low, mid and full load) were studied. The experimental set-up is briefly described as well as the uncertainty of the associated measurements and the development of analytic tools. Then, the evolution of volumetric efficiency, energy share, combustion heat release and exhaust emissions (NOx, particulate matter, CO, unburned hydrocarbons) are described in detail and analysed. Several strategies were considered, including some corrections used in the standard engine control unit to compensate for the low coolant temperature. Some effects of the coolant and oil temperature reduction were clear: increase in friction losses, volumetric efficiency and ignition delay and decrease in NOx emissions. On the contrary, the evolution of brake thermal efficiency, particulate matter, CO and unburned hydrocarbon emission depended on the operating point.

Development of a Mechatronic Control System for a Mechanical Fuel Injection System of a Four Cylinder Automotive Diesel Engine By using Matlab and Simulink

The aim of this paper is to develope a mechatronic control system to replace mechanical fuel injection system of a four-cylinder automotive diesel engine, to study what are the important electronics fuel injection parameters which have the highest effect on the engine performance. All the paperwork performed on Isuzu engine 4HF1 which is 4 cylinder diesel engine working with fully mechanical fuel injection system. To develop mechatronics fuel system, must install crank sensor which measure the engine speed in RPM and specify the piston position, cam sensor which specifies the injection order, common rail fuel injection system which includes electronic injectors, high pressure pump and common rail, ECU which control all the system inputs and outputs and injectors driver controller which responsible for delivering the required high voltage for the injectors with high speed switching. ECU software will be developed from scratch to develop injection quantity, injection time and injection order output signals to be compatible with the common rail fuel system. Mathworks tools (Matlab-Simulink-Stateflow) will be used for developing ECU software application layer which divided into many models as crankshaft speed model, crankshaft sensor piston position, cam sensor injection order model, pedal speed model, injectors model, torque model and final model which collect all the previous models. Embedded coder toolbox will be used for generating C code which will be integrated with the microcontroller layer and uploaded to the selected ECU.

Development of a Mechatronic Control System for a Mechanical Fuel Injection System of a Four Cylinder Automotive Diesel Engine

The aim of this paper is developing a mechatronic control system to replace mechanical fuel injection system of a four-cylinder automotive diesel engine, to study what are the important electronics fuel injection parameters which have the highest effect on the engine performance. All the paper work performed on Isuzu engine 4HF1 which is 4 cylinder diesel engine working with fully mechanical fuel injection system. To develop mechatronics fuel system, must install crank sensor which measure the engine speed in rpm and specify the piston position, cam sensor which specifies the injection order, common rail fuel injection system which includes electronic injectors, high pressure pump and common rail, ECU which control all the system inputs and outputs, and injectors driver controller which responsible for delivering the required high voltage for the injectors with high speed switching. ECU software will be developed from scratch to develop injection quantity, injection time and injection order output signals to be compatible with the common rail fuel system. Mathworks tools (Matlab-Simulink-Stateflow) will be used for developing ECU software application layer which divided into many models as crank shaft speed model, crankshaft sensor piston position, cam sensor injection order model,pedal speed model, injectors model, torque model and final model which collect all the previous models. Embedded coder toolbox will be used for generating C code which will be integrated with the microcontroller layer and uploaded to the selected ECU.

Experimental study of multiple pilot injection strategy in an automotive direct injection diesel engine

The pilot injection strategy is a widely used approach for reducing the noise of the combustion process in direct injection diesel engines. In the last generation of automotive diesel engines up to several pilot injections could occur to better control the rate of heat release (ROHR) in the cylinder as well as the pollutant formation. However, determination of the timing and duration for each pilot injection needs to be precisely optimised. In this paper an experimental study of the pilot injection strategy was conducted on a direct injection diesel engine. Single and double pilot injection strategy was studied. The engine rated power is 100 kW at 4000 rpm while the rated torque is 320 Nm at 2000 rpm. An engine operating point determined by the rotation speed of 1400 rpm and torque of 100 Nm was chosen. The pilot and pre-injection timing was widely varied in order to study the influence on the combustion process as well as on the fuel consumption.

Petroleum Diesel Fuel and Linseed Oil Mixtures as Engine Fuels

The actual problem is the use of alternative biofuels in automotive diesel engines. Insufficiently studied are the indicators of toxicity of exhaust gases of these engines operating on biofuel. The aim of the study is to identify indicators of the toxicity of exhaust gases when using of petroleum diesel fuel and linseed oil mixtures as a fuel for automotive diesel engines. Physical and chemical properties of linseed oil and its mixtures with petroleum diesel fuel are considered. Experimental researches of D-245.12C diesel are carried out on mixtures of diesel fuel and corn oil with a different composition. An opportunity of exhaust toxicity indexes improvement using these mixtures as a fuel for automobiles engine is shown.

Effect of turbo A/R ratio on a high speed turbocharged automotive diesel engine

Effect of turbo A/R ratio on a high speed turbocharged automotive diesel engine

Effect of turbo A/R ratio on a high speed turbocharged automotive diesel engine

In light of the recent trend to improve fuel economy and emission control in diesel engines to meet future energy conservation standards a lot of research is being done on turbocharger. The turbines in turbochargers are characterised mainly by A/R ratio. Varying A/R ratios can adversely affect the performance, fuel economy and emissions of a diesel engine due to effects of pressure boost, back pressure and exhaust gas recirculation. The current study deals with influence of A/R ratios of turbochargers on performance and emissions of a two-cylinder diesel engine. It is found from the experiments carried out that oxides of nitrogen emitted from the engine for all tested turbochargers showed the increasing trend from low to medium engine speeds and it is reverse trend from medium to higher speed range. The other engine emissions unburned hydrocarbon, carbon monoxide and smoke showed the inverse trend of oxides of nitrogen.

Prediction of NOx emissions for high speed DI Diesel engines using a semi-empirical, two-zone model

In the present paper, the authors have applied a newly developed semi-empirical, zero-dimensional, two-zone model on two automotive DI Diesel engines: a heavy (truck) and a light-duty (passenger car) engine. The aim of the study is to examine model’s ability to predict NOx trends with the variation of engine load/speed, fuel injection timing, EGR rate, boost pressure and fuel injection pressure.The model makes use of cylinder geometrical data, basis engine operating data and the experimental combustion rate, as deduced from heat release analysis, to calculate engine tailpipe exhaust NO emissions and their formation history inside the combustion chamber. Apparently, combustion and hence NOx formation, occurs inside the burnt zone. The required air for the combustion is provided from the unburnt zone. The entrained air mass, at each time step, is calculated using a mean equivalence ratio value and the corresponding fuel mass burnt during the calculation time step (as defined by the experimental combustion rate). The mean equivalence ratio value, at each operating point, is obtained using a new correlation which makes use of parameters derived from the processing of the measured pressure trace, as well as typical engine operating parameters. NO (the predominant part of total NOx) is calculated using the extended Zeldovich mechanism at each time step (during combustion and expansion). Thus, the NO formation history inside the cylinder is provided, considering the two-zone approach. The specific concept of the two-zone approach combined with the utilization of engine’s measured parameters, the empirical correlation for the mean equivalent ratio and the simplicity of the model’s calculations, provide a robust and time efficient tool for NO prediction which can be applied on various engine configurations and operating conditions without extended calibration.The derived results reveal model’s ability to predict exhaust NO emissions and trends satisfactorily at a variety of engine settings. Considering its low computational cost, it can serve as a useful tool for emissions trade-off optimization studies, as well as for real-time model based NOx control applications.