High Pressure Common Rail Diesel Research Articles

Investigation of a method for online measurement of injection rate for a high-pressure common rail diesel engine injector under multiple-injection strategies

As a state-of-the-art injection technology, the high-pressure common rail injection system (HPCRIS) has advantages that include high injection pressure, adjustable injection timing and a flexible injection rate. Nevertheless, the fluctuation of cyclic fuel injection mass (CFIM) in the HPCRIS using a multiple-injection strategy (MIS) reduces the economy of the diesel engine and the stability of vibration and noise control. To realize the precise control of CFIM, the online perception of the injection process is the premise. This paper presents an innovative method for online measurement of injection rate under MIS conditions. According to the evolution characteristics of water hammer pressure oscillation in the fuel system, the rule is that the oscillation form of the water hammer is dependent on the structure of the HPCRIS rather than the injection conditions, and the general applicability of this rule is proved by the hydraulic–electric analog method. Based on this, the method for real-time simulation of the pilot water hammer oscillation wave in the same field is proposed to realize the extraction of the expansion pressure signal components of the main injection. Then, the direct mathematical relationship between the pressure signal and fuel injection rate is established, and the online measurement of fuel injection characteristics under MIS is realized. To improve the robustness of the algorithm a method for real-time calibration of fuel sound velocity is proposed. Finally, when compared with the offline experiment, this method for online measurement of injection rate has relatively high accuracy, the CFIM error is less than 2%, and the goodness of fit of the injection rate curve exceeded 0.91. This measurement method can provide direct feedback to the electronic control unit on the fuel injection system without changing the HPCRIS structure.

Experimental study on the high load extension of PODE/methanol RCCI combustion mode with optimized injection strategy

The polyoxymethylene dimethyl ethers (PODE)/methanol reactivity controlled compression ignition (RCCI) mode was realized by direct injection of PODE as high-reactivity fuel to ignite pre-mixed methanol as low-reactivity fuel in a high-pressure common-rail diesel engine. The effects of load extension ratio (LER) on in-cylinder combustion, emission characteristics and fuel economy of RCCI engine were investigated, and the influences of PODE injection strategy on the high-load extension of PODE/methanol RCCI mode were also systematically studied, including the start of main-injection (SOImain), start of pilot-injection (SOIpilot) and pilot-injection quantity (PIQ). The results show that with the increase of LER, the peak values of in-cylinder pressure and heat release rate of RCCI mode increase, the brake thermal efficiency (BTE) and the hydrocarbons (HC), carbon monoxide (CO) and unregulated emissions also increase, but the increase of the ringing intensity (RI), the coefficient of variation of IMEP (COVIMEP) and nitrogen oxides (NOx) limit the further increase of LER. The delay of SOImain can effectively reduce RI, but it will lead to the deterioration of CO and HC emissions and fuel economy. The pilot-injection strategy can weaken the trade-off relationship between NOx and soot emissions and improve combustion stability. With the advance of SOIpilot, the RCCI combustion process evolves from two-stage heat release to single-stage heat release, and the emissions of HC, CO, NOx and soot are reduced. With the increase of PIQ, the combustion phase of PODE/methanol RCCI mode advances, and the RI, COVIMEP and IMEP increase. At 59.5 mg/cycle condition, when PIQ is increased from 2 mg to 10 mg, CO and HC emissions decrease by 19.57% and 6.97% respectively, while NOx emissions increase by 7.93%. With the appropriate LER combined with the optimized PODE injection strategy, the BTE of PODE/methanol RCCI engine reaches 48.68%, and the IMEP is extended from 0.77 MPa to 1.08 MPa.

Experimental investigation into the pore structure and oxidation activity of biodiesel soot

To investigate the effect of diesel fuel and different fatty acid methyl esters (FAMEs) biodiesels on the pore structure and oxidation activity of exhaust soot, an experiment was performed on a 4-cylinder high-pressure common-rail diesel engine fueled with commercial diesel fuel and three types of biodiesels (used soybean oil methyl eater (SME), palm oil methyl eater (PME), and waste cooking oil methyl eater (WME) as the main resources, respectively). Results showed that four kinds of exhaust soot had similar porous morphology, while the C/O ratio of biodiesel soot was lower than diesel soot. The N2 adsorption of four kinds of soot belonged to the multi-layer adsorption of mesopore or macropore media, and the N2 adsorption capacity of biodiesel soot was more substantial than that of diesel soot. The specific surface area, the pore volume, and the fractal dimension of three biodiesel soot were larger than that of diesel soot, and the mean pore size was smaller, which meant that the porosity of biodiesel soot was higher than that of diesel soot, and it had a rougher surface. Biodiesel particles contained more aliphatic C–H surface functional groups (SFGs), which may be related to the adsorption of more soluble organic fractions (SOF) by soot surface. A larger surface area and a higher porosity of biodiesel soot also improved the reactivity of soot. The iodine number and oxygen content of biodiesel had a significant effect on the pore structure and oxidation activity of soot. The low iodine number and high oxygen content of biodiesel (mainly consist of WME) helps to reduce PM emissions and improve the porosity and oxidation activity of biodiesel soot.

Solubility limitations of residual steryl glucosides, saturated monoglycerides and glycerol in commercial biodiesel fuels as determinants of filter blockages

AbstractNewer, improved high pressure common rail diesel engines require increased protection from damaging particles in fuel, resulting in tighter, low‐micron filtration requirements. The unobstructed flow of fuel through filters underlies the well‐known efficiencies and reduced exhaust emissions of diesel engines, and when flows are hindered, these efficiencies become severely compromised. Biodiesel fuels frequently contain saturated monoglycerides, glycerol (GLY) and/or steryl glucosides, systemic impurities that become problematic when low concentrations exceed ill‐defined solubility limits, usually unexpectedly at low temperatures. Here, filters and blended fuels from seven flow obstruction incidents were subjected to detailed compositional analyses. With one exception the fuels contain estimated levels within international specifications, yet exhibit heterophase (HP) formation in the laboratory at 2°C, well above measured cloud points. Feedstock composition, pretreatment and/or purification processes are found to modulate insolubility risks. Interferences in standard gas chromatography methods used without modification can hide or complicate estimates of residual levels of GLY. The data show that classical variables controlling solubility, such as concentrations and temperatures, play important roles in setting the risks associated with in situ formation of HPs from these common impurities. Further, such risks are likely attenuated considerably by reductions in critical impurities beyond currently specified limits.

Research on a small sample fault diagnosis method for a high-pressure common rail system

In the fault diagnosis of high-pressure common rail diesel engines, it is often necessary to face the problem of insufficient diagnostic training samples due to the high cost of obtaining fault samples or the difficulty of obtaining fault samples, resulting in the inability to diagnose the fault state. To solve the above problem, this paper proposes a small-sample fault diagnosis method for a high-pressure common rail system using a small-sample learning method based on data augmentation and a fault diagnosis method based on a GA_BP neural network. The data synthesis of the training set using Least Squares Generative Adversarial Networks (LSGANs) improves the quality and diversity of the synthesized data. The correct diagnosis rate can reach 100% for the small sample set, and the iteration speed increases by 109% compared with the original BP neural network by initializing the BP neural network with an improved genetic algorithm. The experimental results show that the present fault diagnosis method generates higher quality and more diverse synthetic data, as well as a higher correct rate and faster iteration speed for the fault diagnosis model when solving small sample fault diagnosis problems. Additionally, the overall fault diagnosis correct rate can reach 98.3%.

Gasoline spray characteristics using a high pressure common rail diesel injection system by the method of laser induced exciplex fluorescence

The liquid and vapor phases of gasoline sprays were investigated using a common rail diesel injection system in a constant volume vessel by laser induced exciplex fluorescence (LIEF) and compared with diesel sprays. The effects of injection pressure and ambient pressure on gasoline sprays were measured under evaporating conditions. The results reveal that: the liquid phase penetration has a little change as the fuel is injected, while the vapor phase penetration increases constantly with obvious branch-like structures generated at the downstream vapor phase. The spray volume and mass of entrained gas both increase roughly linearly versus the mass of injected fuel. Compared with diesel sprays in similar conditions, gasoline sprays display a significantly shorter liquid penetration, while a smaller difference between the vapor penetration lengths of gasoline and diesel sprays is observed. The maximum equivalence ratio of gasoline sprays is still more than 2 at selected conditions. As the ambient pressure increases, the penetration lengths of liquid and vapor phases both reduce, and the mean equivalence ratio also decreases with a drop of spray volume. Conversely, the mass of entrained gas rises continually. With the increase of injection pressure, the liquid phase penetration length maintains almost no change. However, the vapor penetration length shows a declined trend during the injection pressure rise at iso-injected fuel mass condition. The spray volume and mass of entrained gas give a slight reduction when the injection pressure enhances. Oppositely, the mean equivalence ratio presents an increased tendency with similar mass of injected fuel.

Parameter optimization analysis of fuel injection system for high pressure common rail diesel engine

The cleaning and energy-saving environmentally friendly diesel engine, with the high pressure common rail fuel injection system, is the main driving force in the transportation sector. Being the core and key technology, the high pressure common rail fuel injection system is the inevitable developing trend of the future fuel injection system. The parameter optimization design of the high pressure common rail fuel injection system is of great practical significance to improve. the operation stability of common rail system. By up-grading the fuel control precision and optimizing the overall performance of the engine, the purpose of energy saving and emission reduction can be finally achieved.

Experimental study on the effects of blending PODEn on performance, combustion and emission characteristics of heavy-duty diesel engines meeting China VI emission standard

To study the influence of diesel fuel blended with polyoxymethylene dimethyl ethers (PODEn), a new alternative fuel with a high oxygen content and large cetane number, on the combustion characteristics, fuel economies, and emission characteristics of heavy-duty diesel engines that meet China VI emission standards, relevant tests were conducted on a supercharged intercooled high-pressure common-rail diesel engine. The PODEn were blended with diesel fuel at three different ratios (volume fractions of 10%, 20%, and 30%). The test results showed that the PODEn could optimize the combustion process of diesel engines that met the China VI emission standards, effectively improve the thermal efficiencies of diesel engines, and reduce the emissions of hydrocarbon (HC), carbon monoxide (CO), and soot. With an increase in the PODEn blending ratio, the peak values of the in-cylinder pressure, average in-cylinder temperature, and instantaneous heat release rate gradually decreased, and each peak progressively moved forward. As the start of combustion gradually moved forward, the combustion duration was shortened by 0.7–2.8°CA, the heat release process became more concentrated, and the effective thermal efficiency was increased by up to 2.57%. The effective fuel consumption gradually increased, yet the equivalent effective fuel consumption gradually decreased, with the largest drop being as high as 4.55%. The nitrogen oxides (NOx) emission increased slightly, and the emissions of HC, CO, and soot gradually decreased. The emissions of CO and soot declined significantly under high-speed and high-load conditions, with the highest reductions reaching 66.2% and 76.3%, respectively.

Research on the Characteristics of Operating Non-Uniformity of a High-Pressure Common-Rail Diesel Engine Based on Crankshaft Segment Signals

This paper studies the operating uniformity of a high-pressure common-rail diesel engine based on crankshaft segment signals. Engine nonuniformity or unevenness refers to the crankshaft torque fluctuation caused by cylinder-to-cylinder differences, which are caused by misfiring or difference in fuel supply or air supply. The experiments were conducted on a diesel engine of the YN30CR model. Based on the relationships among the cylinder pressure, the instantaneous crankshaft angular speed, and the crankshaft segment signal, it is found that the crankshaft segment signal can be used to characterize the operating nonuniformity of the diesel engine. Based on the Fast Fourier Transformation (FFT) from the angular domain to the frequency domain in analyzing the fluctuation patterns of the crankshaft segment signals at different operating conditions, the nonuniformity information was extracted. In order to further reveal the relationship between the fluctuation phenomena of the crankshaft segment signal and the cause of the fluctuation, the torque acting on the crankshaft of the multi-cylinder diesel engine was studied to quantify the operating nonuniformity of the diesel engine. The results show that the crankshaft segment signal can reflect the uniformity of the engine torque very well in both phase and amplitude, and the degree of nonuniformity of the engine torque can be reflected by the amplitudes of the low-order non-dominant harmonics of the crankshaft segment signal below the firing frequency. The crankshaft segment signal is very consistent with the variation pattern of the engine torque.

Analysis of out-of-round deformation of a dry cylinder liner of a non-road high-pressure common-rail diesel engine based on multi-field coupling

The deformation of cylinder liner directly affects the sealing performance of the friction components in internal combustion engines, resulting in high oil consumption, engine power loss, and high-particulate matter emissions. Previous research works focused more on deformation of the wet vehicular cylinder liners, however, the effects of different loads on the dry liner deformation is not clear yet. A non-road high-pressure common-rail diesel engine was selected as the research object, and a coupled model of the engine was developed based on fluid–solid coupled heat transfer theory. After the accuracy of the model was verified by temperature measurement of the cylinder head and cylinder liner, deformation of the dry cylinder liner was studied. The results show that the axial and radial deformations of the cylinder liner are not uniform under the bolt preload condition. Large deformation occurs at the first liner and fourth liner, with the maximum deformation occurring at the top of fourth liner for 10.14 μm. Under the condition of thermal load, the temperature of cylinder liner exhibits a distribution of three-segments from the top to bottom. The liner deformation is not uniform, and the maximum deformation occurs at the top of the fourth liner for 304 μm. The radial deformations of all four cylinder liners present a symmetrical structure of a “heart” shape with respect to the centerline of the second and third cylinders. The axial deformation of each liner exhibits a “barrel” shape which is convex in the middle and narrow at the two ends.

Oxidation behaviors and nanostructure of particulate matter produced from a diesel engine fueled with n-pentanol and 2-ethylhexyl nitrate additives

Experiments were performed on a high pressure common-rail diesel engine fueled with D100 (diesel fuel), DP15 (15% n-pentanol and 85% diesel, v/v), DP30 (30% n-pentanol and 70% diesel, v/v), DP30E1 (DP30 and 1000 ppm EHN) and DP30E2 (DP30 and 2000 ppm EHN), respectively. Particulates were sampled from the engine exhaust tailpipe and further analyzed with transmission electron microscope (TEM), Raman spectroscopy (RS) and thermogravimetric analysis (TGA). Results showed that an increase in soot oxidation reactivity was observed with increasing n-pentanol concentration in diesel/n-pentanol mixtures. This trend was in line with the poorer structural ordering of soot particles generated from blended fuels by both TEM and RS analyses. Regarding the impact of EHN addition to DP30 fuel, the soot oxidation reactivity decreased as the fuel was changed from DP30 to DP30E1, and then increased as the fuel was changed from DP30E1 to DP30E2. Notably, the soot from DP30 + EHN additive was easier to be oxidized than that from DP30. Similarly, the trends in soot oxidation reactivity with EHN additive can qualitatively capture the variations in soot nanostructure. The correlation between soot reactivity and nanostructure in this study was nonlinear, which infers that soot oxidation reactivity would be also influenced by other features like active surface area and surface functional group. It can be suggested that the application of DP30 would significantly affect the regeneration performance of diesel particulate filter (DPF); when the baseline fuel is DP30, the impacts of EHN additives on regeneration performance of DPF are relatively slight.

Experimental Research on Exhaust Thermal Management Control Strategy for Diesel Particular Filter Active Regeneration

The regeneration was the main barrier restricting the development of diesel particulate filter (DPF), and the exhaust thermal management control strategy are the premise of efficient DPF active regeneration. This paper took a light vehicle equipped with high-pressure common rail diesel engine as the object, studied the influences of exhaust thermal management including intake throttling, fuel injection strategies and late post injection (LPI) coupling diesel oxidation catalyst (DOC) on exhaust temperature by experiment. The results indicated that the reduction of intake throttle valve opening at low speed and light load working conditions, where the exhaust temperatures were low, could dramatically increase the exhaust temperature. With a reasonable match of fuel injection parameters, the exhaust temperature could be increased. LPI coupling DOC could have a further increment on exhaust temperature, but it would have obvious negative effects on fuel economy and hydrocarbon emissions at the same time. In this paper, a comprehensive exhaust thermal management control strategy was proposed. The test bench indicated clearly that the demand of DPF regeneration temperature can be met in most working conditions through the reasonable integrated control strategies of exhaust thermal management.

Alexandrian Laurel for Biodiesel Production and its Biodiesel Blends on Performance, Emission and Combustion Characteristics in Common-Rail Diesel Engine

A two-step transesterification process was employed in the biodiesel production from non-edible Alexandrian Laurel. The key physicochemical properties of the Alexandrian Laurel biodiesel (ALB), diesel and blends of both fuels were compared and analyzed. The effects of blending biodiesel (ALB) and petroleum diesel on engine performance, combustion and exhaust emissions were investigated in a turbocharged, high-pressure common-rail diesel engine under six different speed operations and at full load conditions. The test fuels comprised a conventional diesel fuel and four different fuel blends of ALB. The results showed relatively close physicochemical properties of ALB and its blends when compared with petroleum diesel. However, the use of ALB-blended fuel resulted in penalties engine brake power, brake specific fuel consumption (BSFC) despite slightly improved brake thermal efficiency (BTE). Brake specific nitrogen oxide (BSNOx) was found worsened with higher ALB content in the blends. Nonetheless, consistent improvements in brake specific carbon monoxide (BSCO), brake specific carbon dioxide (BSCO2), and smoke were noticed when ALB blends were used. Additionally, ALB blends contributed to reduction in peak combustion pressure, peak heat release rate (HRR) and combustion duration. In general, the findings suggest satisfactory operation with ALB biodiesel-diesel blends in an unmodified diesel engine.

Exploring the high load potential of diesel–methanol dual-fuel operation with Miller cycle, exhaust gas recirculation, and intake air cooling on a heavy-duty diesel engine

Legislations concerning emissions from heavy-duty diesel engines are becoming increasingly stringent. This requires conventional diesel combustion to be compliant using costly and sophisticated aftertreatment systems. Preferably, diesel–methanol dual-fuel is one of the suitable alternative combustion modes as it can potentially reduce the formation of nitrogen oxide and soot emissions which characterised the diesel mixing-controlled combustion. This is primarily due to the high latent heat of vaporisation and oxygen content of the methanol fuel. At high engine loads, however, the potential of diesel–methanol dual-fuel operation is constrained by the excessive combustion pressure rise rate and peak in-cylinder pressure, which limits both the engine efficiency and the percentage of methanol that can be used. For the first time, experimental studies were conducted to explore advanced combustion control strategies such as Miller cycle, exhaust gas recirculation, and intake air cooling for improving upon high load diesel–methanol dual-fuel combustion. Experiments were carried out at 1200 r/min and 18 bar indicated mean effective pressure on a single-cylinder heavy-duty diesel engine, which equipped with a high pressure common rail diesel injection, a methanol port fuel injection, and a variable valve actuation system on the intake camshaft. Results showed that the methanol energy fraction of a conventional diesel–methanol dual-fuel operation with a baseline intake valve closing timing was limited to 28%. This was due to the high combustion temperature at a high load which advanced the ignition timing of the premixed charge, resulting in high levels of pressure rise rate. The application of lower effective compression ratio and intake air temperature ( Tint) effectively decreased the compression temperature, which successfully delayed the ignition timing of the premixed charge. This allowed for a more advanced diesel injection timing to achieve improvement in the thermal efficiency and potentially enabled a higher methanol substitution ratio. Although the introduction of exhaust gas recirculation demonstrated very slight impact on the ignition timing of the premixed charge, a higher net indicated efficiency was observed due to a relatively lower local combustion temperature which reduced heat transfer loss. Moreover, the optimised diesel–methanol dual-fuel operation allowed a higher methanol energy fraction of 40% to be used at an effective compression ratio of 14.3 and Tint of 305 K and achieved the highest net indicated efficiency of 47.4%, improving by 3.7% and 2.6%, respectively, when compared to the optimised conventional diesel combustion (45.7%) and conventional diesel–methanol dual-fuel (46.2%). This improvement was accompanied with a reduction of 37% in nitrogen oxide emissions and little impact on soot emissions in comparison with the conventional diesel combustion.

Effect of Injection Parameters on Vibration of High Pressure Common Rail Diesel Engine for Light Vehicle at Idle Speed

With the progress of science and technology and the improvement of people’s living standards, the comprehensive performance requirements of automobiles are also increasing. Reducing engine’s vibration and noise is one of the important research contents in the field of automobile research. An experimental study was performed to investigate the effect of injection parameters on engine’s vibration at idle speed by using a four-cylinder high pressure common rail diesel engine. On the premise of not changing the components, the influence of each parameter on the vibration is compared and analyzed by changing the parameters such as main injection timing, interval of pilot-main injection, pilot injection quantity and rail pressure. The test results show that the vibration of diesel engine can be reduced by delaying the main injection timing properly, and the optimal interval of pilot-main injection is related to the main injection moment and the quantity of fuel injection. The determination of the pilot injection quantity must be determined by the pilot-main injection moment and the cycle injection quantity together in order to achieve vibration reduction. The increase of rail pressure will increase the vibration of the whole machine. Thus, the proper injection strategy is conducive to improve engine vibration characteristics.

Effect of Fuel Ignitability and Volatility on Ultra-Fine Particulate Emissions in Diesel Engine

The effects of fuel components on particulate matter emissions were studied on a high pressure common rail diesel engine fuelled with different diesel fuels. Six kind of diesel fuels with various volatility and ignitability were selected in this test. Particle number, composition and morphology were studied with various physicochemical property diesel fuels. The results show that lower ignitability fuel and stronger volatility fuel could reduce the accumulation mode particle number, while the nucleation mode particle number would increase. Meanwhile, the proportion of DS might reduce with the SOF increase. With the decrease of the fuel cetane number, the number of large cluster particles in the exhaust decreased obviously.

Scaling liquid penetration in evaporating sprays for different size diesel engines

Scaled model experiments can greatly reduce the cost, time and energy consumption in diesel engine development, and the similarity of spray characteristics has a primary effect on the overall scaling results of engine performance and pollutant emissions. However, although so far the similarity of spray characteristics under the non-evaporating condition has been studied to some extent, researches on scaling the evaporating sprays are still absent. The maximum liquid penetration length has a close relationship with the spray evaporation processes and is a key parameter in the design of diesel engine spray combustion system. In this article, the similarity of maximum liquid penetration length is theoretically derived based on the hypotheses that the spray evaporation processes in modern high-pressure common rail diesel engines are fuel–air mixing controlled and local interphase transport controlled, respectively. After verifying that the fuel injection rates are perfectly scaled, the similarity of maximum liquid penetration length in evaporating sprays is studied for three scaling laws using two nozzles with hole diameter of 0.11 and 0.14 mm through the high-speed diffused back-illumination method. Under the test conditions of different fuel injection pressures, ambient temperatures and densities, the lift-off law and speed law lead to a slightly increased maximum liquid penetration length, while the pressure law can well scale the maximum liquid penetration length. The experimental results are consistent with the theoretical analyses based on the hypothesis that the spray evaporation processes are fuel–air mixing controlled, indicating that the local interphase transports of energy, momentum and mass on droplet surface are not rate-controlled steps with respect to spray evaporation processes.

Investigating the impact of copper leaching on combustion characteristics and particulate emissions in HPCR diesel engines

Copper leaching in diesel fuel and its impact on combustion and emission characteristics of a Direct Injection High Pressure Common Rail (DI HPCR) diesel engine was investigated. This work was performed using a single cylinder Ricardo Hydra research engine fitted with a cylinder head, piston assembly, and crankshaft from a production 2.2 L DI diesel engine. A fuel conditioning device consisting of a helicoidally shaped copper duct and electromagnetic coils powered from the battery was installed along the fuel line just before the high pressure pump. A diesel fuel with a copper content of less than 0.2 ppm was used. Inductively coupled plasma mass spectrometry (ICP-MS) analysis showed an increase of copper content to 1 ppm when fuel flowed through the conditioning device prior to the injection and returned from the engine back to the fuel tank. Copper leaching from the conditioning device was confirmed using a bespoke test rig. Combustion characteristics were analysed via post-processing pressure measurements, while an AVL Smoke Meter was used to monitor particulate emissions. A pilot plus main strategy was used to achieve a target Brake Mean Effect Pressure (BMEP) typical of medium load. Soot reduction in the range of 7–14% was measured when the device was connected to the fuel line, compared to the baseline. The initiation and early development of combustion was also investigated using an unstirred, quiescent combustion chamber with optical access. High-speed photography showed that ignition probability was enhanced in presence of the fuel conditioning device.

Development on ECU for the 32-bit High Pressure Common-rail Diesel Engine Based on AUTOSAR ECU Software

In order to facilitate the development of the diesel engine ECU, based on AUTOSAR ECU software architecture and MPC554 microcontroller, the ECU basic platform which includes of diesel engine ECU hardware and ECU basic software library is established, as well as the overall common rail ECU is achieved. This ECU basic platform of the diesel engine provides reliable hardware system, drive module interface, two-stage injector configuration control waveform output and OBD system. It is convenient to ECU development which improves the developing efficiency, shortens the developing cycle and has a high practical value.

Effects of gasoline and iso-butanol addition on combustion and pollutant emissions of a common-rail diesel engine at different injection timing

Combustion and pollutant emissions from a high pressure common-rail diesel engine using ternary diesel/gasoline/iso-butanol blends were investigated experimentally in order to improve combustion process and farther decrease emissions of diesel/gasoline blends. The experiments were carried out at five injection timings under medium engine load. Four fuels were tested in this work, D100 (pure diesel) was tested for baseline comparison, the other three fuels were DG (30% gasoline in diesel fuel by mass), DGB (15% gasoline and 15% iso-butanol in diesel fuel) and DB (30% iso-butanol in diesel fuel). Experimental results indicate that DG, DGB and DB delayed the ignition timing periods and shortened the combustion durations, resulting in higher levels of premixed combustion and maximum pressure rise rates (MPRRs). Meanwhile, DGB and DB showed higher brake thermal efficiencies (BTEs) than DG and D100. It was also found that adding gasoline and iso-butanol, substantial decrease in carbon monoxide (CO) emissions, particulate diameters, nucleation mode (NM) and accumulation mode (AM) particle numbers were achieved, but the emissions of unburned hydrocarbons (HC) and nitrogen oxides (NOx) were increased slightly. DGB and DB produced better NOx-particulate matter (PM) trade-off than DG and D100 in combination with retarded injection timing. Furthermore, PM emitted from blend fuels showed higher ratios of sub-10 nm particle number concentrations, the sequence is D100 < DG < DGB < DB, which may be more harmful to human health.