Higher Fuel Injection Pressure Research Articles

A new track for high-efficiency marine diesel engines: Initiative air jet and post-split injection combined

In pursuit of adequate mixing with a high volume of fuel injection, a re-intake scheme is proposed to promote the diffusion of combustibles and flames by using the disturbance of high-pressure air jets after the pressure peak. The results indicate that during the power stroke, an additional air jet enhances combustion by penetrating the spray and disturbing the flame front. The high-pressure air jet's obstruction of the atomization of local sprays achieves a longer combustion duration, while intensifying the vortex and temperature at the cylinder center, which enhances the evaporation of fuel near the nozzle. However, excessively high fuel injection pressure brings in more cold air, causing a temperature drop. It is necessary to have sufficient flame expansion before re-intake to eliminate the impact on pressure. By adjusting the re-intake pressure and timing, the air jet, when it reaches half the cylinder diameter, can exert its maximum advantage. By introducing post-injection and increasing the pressure of the first fuel injection, the air-spray impingement duration is extended, thereby improving thermal efficiency. This work, at 190 MPa injection pressure without changing the duration, and combined with a 5°CA re-intake, achieved a 1.82 % increase in thermal efficiency.

Effect of fuel injection pressure on biodiesel blended combustion of Inland River diesel engine

Abstract Compared with ordinary diesel, biodiesel has greater viscosity, density, and flash point, especially under medium and low load, which is easy to cause poor atomization and inadequate combustion. In this paper, an in-line six-cylinder inland river ship diesel engine was used as a model to conduct simulation tests under 50% load of propulsion characteristics to explore the effects of different fuel injection pressures on oil-gas mixing, combustion, and emission of fuel blended with a small percentage of biodiesel. The results show that the increase of fuel injection pressure can enhance the average turbulence intensity in the cylinder as well as increase the relative flow velocity between oil and gas, which is beneficial to the mixture combustion. High fuel injection pressure will promote flame propagation, increasing the maximum burst pressure and the average temperature in the cylinder. Compared to the fuel injection pressure of 24 MPa, NOx emission increases by 5.5% and 15.6% respectively at 27 MPa and 30 MPa, and decreases by 10% and 25% respectively by SOOT.

Effect of pilot fuel quantity and fuel injection pressure on combustion, performance and emission characteristics of an automotive diesel engine

The work presented here experimentally investigates the effect of pilot quantity (PQ) on combustion, performance and emission characteristics of an automotive diesel engine. All the experiments were performed at max torque speed of the test engine (1600 rpm) and 75 % of full engine load. Three PQs under consideration are 10 %, 20 % and 30 % of total fuel mass per cycle while maintaining the fixed pilot as well as main injection timings. The minimum PQ (10 %) considered in the study was found sufficient to enhance the in-cylinder thermodynamic conditions before main injection starts. Also, fuel injection pressure (FIP) was maintained constant at 500 bar initially. Obtained results showed that the pilot injection mode with 30 % PQ reduced nitrogen oxide (NO) emission as well as brake specific fuel consumption (BSFC) by 21.87 % and 1.46 % respectively compared to reference single injection mode while smoke emissions were increased by 77.64 %. In order to curb this negative effect of higher smoke emissions offered by pilot injection, FIP was increased from 500 bar to 700 bar and similar experiments were repeated. The experimental results demonstrated that higher FIP significantly reduced smoke emissions as well as fuel consumption under all the considered pilot injection modes with acceptable rise of NO emission which was still considerably lower than reference single injection mode. For e.g., when FIP was increased from 500 bar to 700 bar in case of pilot injection mode with 30 % PQ, smoke emissions and BSFC were reduced by 26.40 % and 2.14 % respectively, while NO emission was increased by 6.30 %. Therefore, it can be said that combination of pilot injection and high FIP leads to overall improvement in performance and emission characteristics of the test engine.

Effect of FIPs strategy and nanoparticles additives into the renewable fuel blends on NOX emissions, PM size distribution and soot oxidation in CRDI diesel engine

‏ The search of next prospective source of fuel is highlighted by the research community to compensate the aspects of shortcomings of diesel fuel and to treat the harmful emissions in the transportation sector. Among numerous economic sectors, the use of petro-diesel still the main fuel using for driving heavy machinery despite the high advance in electric motors for transportation systems. The characteristics of engine performance, nitrogen oxide (NOX) emissions, size distribution of particulate matter (PM), number and oxidation reactivity of soot particles from the effects of low and high fuel injection pressures (FIPs) and adding two types of nanoparticles (Al2O3 and TiO2) to the M20B10 blend (20 % of microalgae biodiesel, 10 % n-butanol and 70 % of diesel) were studied in common-rail diesel engine at different loads. The results revealed that the adding Al2O3 and TiO2 to the M20B10 blend decreased the BSFC by 21.28 % and 22.84 %, respectively, and also improved BTE by 4.46 % and 2.35 %, respectively, for different engine loads. It is observed that the applied HFIP and M20B10+Al2O3 blend also enhance the fuel consumption by 21.28 % and increase BTE by 9.63 % in comparison with M20B10+ TiO2 blend. In contrast, the presence HFIP with nano blends increased the NOX emissions by 24.73 % with respect to the LFIP, meanwhile the NOX emissions decreased from nano blends combustion more than to the neat M20B10 blend. The combustion of M20B10+Al2O3 blend decreased the PM concentration (by 52.82 %) and number (by 33.62 %) and when compared with blend of M20B10+ TiO2 and neat M20B10 blend combustion at HFIP. Furthermore, the reactivity of soot oxidation significantly increased when adding Al2O3 into the M20B10 blend and applying HFIP compared to the M20B10+ TiO2 blend.

Impact of titanium dioxide (TiO2) nanoparticles addition in Eichhornia Crassipes biodiesel used to fuel compression ignition engine at variable injection pressure

Power production through combustion of fuels plays a vital role in the progress of a nation. In liquid fuels, biodiesel has emerged as a potential replacement of fossil fuel. In this regard, the improvement of fuel properties or adjustment of the operating parameters can improve the efficiency and lower the emission for a biodiesel run diesel engine. In this regard, the current study focuses on the use of novel nano blended biodiesel, prepared by blending titanium dioxide nano particles along Eichhornia Crassipes biodiesel. Three different biodiesel blends are prepared having composition of titanium dioxide by 50 ppm, 100 ppm and 150 ppm which is tested in a four stroke, single cylinder, naturally aspirated water cooled diesel engine of 3.5 kW rated power for different loading conditions for performance, emission, and combustion evaluation. Further, at the same engine conditions, the biodiesel blend having 150 ppm of titanium dioxide is tested at fuel injection pressure of 220 bar. The findings suggests that the brake thermal efficiency improves and emissions lowers with the addition of nano particles at high fuel injection pressure. The maximum improvement of brake thermal efficiency of 1.01% in comparison to diesel mode has been found for nano blended biodiesel composition of 150 ppm of titanium dioxide at fuel injection pressure of 220 bar under full loading condition. For the same fuel injection pressure of 220 bar and same nano blended biodiesel composition, the hydrocarbon and carbon monoxide emission were found to minimum at 60% load.

Operational Control of Power Indicators of Diesel Engines with Common Rail Fuel System

Introduction. Operational methods to monitor the power indicators of engines for continuous diagnosis of their technical condition are of particular interest for creating optimal operating conditions of motor and tractor machinery. The methods are characterized by the mechanical efficiency, determined in the conditions of repair shops with the use of complex braking devices. Aim of the Article. To present the results of research on the development of an operational method for determining the mechanical efficiency of diesel engines with batteryoperated electronically controlled fuel supply systems. Materials and Methods. The Bashkir State Agrarian University proposed and successfully tested an operational method for assessing the technical condition of diesel engines with direct-acting fuel equipment on their mechanical efficiency, which is determined by the performance of their fuel equipment adjusted using the diesel itself as an adjusting stand. The possibility of using the proposed method for diesel engines with storage fuel systems was investigated. Results. The accuracy of determining the mechanical efficiency of diesel engines by electronically controlled fuel systems of battery type can be affected by the features of their work – the correction of cyclic feeds by the electronic engine control unit depending on the technical condition of the cylinders and high fuel injection pressure. To test this hypothesis, there were carried out studies on a four-cylinder D4EA 2.0 engine of a Hyundai Tuscon car with a Common Rail type storage fuel system. The engine fuel supply system was supplemented with an electronic unit integrated between the injector and the standard engine control unit, which interrupted the transmission line of the control signal to the injector according to a given algorithm without the standard unit transition to emergency mode. It has been found that the proposed method can successfully determine the technical condition of the engine as a whole and of its individual cylinders (alternating disabled and working cylinders). Discussion and Conclusion. The proposed operational method for determining the mechanical efficiency can be successfully used for diesel engines with accumulator electronically controlled fuel supply systems. At the same time, an increase in the cyclic supply by the electronic control unit of the engine fuel supply system reduces the mechanical efficiency slightly, and it can be taken into account only in special cases.

Influence of fuel injection parameters at low-load conditions in a partially premixed combustion (PPC) based heavy-duty optical engine

The study examined the effects of second injection timings and fuel injection pressures (FIPs) in a double-injection based partially premixed combustion (PPC) using a single-cylinder heavy-duty optical diesel engine equipped with two different configurations, namely all-metal and optical. The thermodynamic analysis of energy balance, exhaust emissions, and particulates characterization was conducted in an all-metal engine configuration. For the same base engine architecture, high-speed natural combustion luminosity, cool-flame, and electronically excited hydroxyl (OH*) chemiluminescence, and planar laser-induced fluorescence (PLIF) imaging of formaldehyde (HCHO-PLIF) were applied in the optical configuration. Additionally, 1D modeling using GT-Power was utilized to examine the distribution of heat transfer losses through the individual cylinder boundaries. The experiments were conducted at low-load conditions at a fixed fuel mean effective pressure (MEPfuel) using a primary reference fuel with a volumetric mixture of 50% n-heptane and 50% iso-octane (PRF50). The results demonstrated that for a fixed first injection, the second injection timing of −6°CA aTDC is the most favorable condition due to increased gross indicated efficiency, reduced exhaust losses, decreased uHC/CO/soot emissions with a slight compromise on heat losses and NOx emissions. Among the tested FIPs of 1200, 1500, and 1800 bar, 1500 bar showed higher efficiency, and overall lower energy losses and exhaust emissions. At higher FIPs, the overall flame development process revealed reduced luminous intensity with dispersed signals formed downstream of the nozzle due to increased premixed combustion. For 1800 bar FIP, both cool-flame and HCHO signals showed an increased rate of reaction zones close to the bowl-wall region from where the OH radicals developed. Not only the initial low- to high-temperature reaction transition was faster for 1800 bar FIP but the signal decay of HCHO signals by OH radicals was also rapid in the late cycle. These findings explained the root cause of increased heat transfer losses and higher uHC/CO emissions at 1800 bar FIP.

Effect of Pilot Injection with Various Starts of Second Injection Command (SOIC2) and Fuel Injection Pressures on Gasoline Compression Ignition Combustion

This experimental study was conducted using a single-cylinder compression ignition (CI) engine with a pilot injection strategy to determine the effect of fuel injection pressure and the timing of the second start of injection (SOI2) on combustion and emission characteristics. This experiment used a mixture of 80% commercial gasoline (G80%) and 20% soybean biodiesel (B20%), by volume. The pilot injection strategy was applied with varying SOI2. Meanwhile, the first start of injection (SOI1) was constant at -350° ATDC and 900 bar fuel injection pressure. A range of fuel injection pressures from 400 to 900 bars and varied injection timing from -44 to -36 CA ATDC was applied at SOI2 to analyze the effect of injection timing and injection pressure on combustion characteristics and emissions. The increasing fuel injection pressure of GB20 in early injection timing will cause a longer ignition delay. The autoignition resistance of GB20 and the improvement of spray velocity enhance the wall wetting probability, consequently reducing the autoignition capability as fuel deposits were formed in the cylinder wall vicinity. Closer injection timing to TDC inhibits spray penetration due to higher room pressure and density, causing lower ignition delay. For GB20, 700 bar fuel injection pressure became the turning point in the ignition delay due to a lower fuel penetration velocity as a higher fuel injection pressure was applied. NOx emissions were identified as a sign of high temperature produced during combustion. The lowest CO2 emissions and the longest ignition delay appeared at the 700-bar injection pressure. Because incomplete combustion resulted in fuel deposits in the vicinity of the cylinder and temperature decrease, injection timings earlier than 40°CA BTDC initiated low thermal reaction (LTR) conditions, causing a temperature decrease during combustion.

МОДЕРНИЗАЦИЯ СИСТЕМЫ ТОПЛИВОПОДАЧИ ДИЗЕЛЯ НЕПОСРЕДСТВЕННОГО ДЕЙСТВИЯ ПОВЫШЕНИЕМ ИНТЕНСИВНОСТИ ВПРЫСКИВАНИЯ

The research was carried out with the aim of increasing the intensity and pressure of fuel injection in direct-acting fuel supply systems of a diesel engine to improve the quality of its work and reduce consumption. To achieve it, on the basis of theoretical studies, the cam profile of the diesel fuel equipment was modernized using the sinusoidal law of plunger motion. The resulting analytical expression of the sinusoidal law of plunger displacement (from the condition of ensuring its shockless and continuous movement along the cam) makes it possible to calculate the cam profile, which provides an increase in the flow rate and high fuel injection pressure. Taking into account the boundary conditions (based on the overall dimensions of the existing 4UTNI pump) and the permissible level of load on the shaft bearing, the profile, speed and acceleration of the cam were calculated. The manufactured experimental pump with a calculated camshaft of a sinusoidal profile showed good results in comparative tests with the existing standard diesel high-pressure pump D-144. For the improved high-pressure fuel pump, the injection intensity and injection pressure in the nominal mode were 9% higher compared to the standard 4UTNI pump, at a low crankshaft speed, the pressure was 20% higher, and the flow rate was 35%. Increasing the injection rate and fuel injection pressure reduces the pusher lift time. At the same time, the cross-sectional uniformity of fuel supply at a shaft speed of n= 1000 min-1 increases by 1.1%, at n= 200 min-1 - by 18%.

Investigation of high fuel injection pressure variation on compression ignition engines powered by jatropha oil methyl ester-heptanol-diesel blends

The fast depletion of the petroleum reserves and the rising environmental threats have created an urgent need for sustainable-alternate fuels for the transport and agricultural sectors. In this regard, the ternary blends (diesel–biodiesel-alcohol) have the potential to address the above concerns as they offer huge potential in mitigating exhaust emissions and enhancing engine performance. In the present work, jatropha biodiesel and heptanol have been used as oxygenated additives in the ternary blends in order to save considerable quanta of diesel fuel by restricting its volumetric content to only 40 %. In addition, the fuel injection pressure (IP) is a vital factor that determines the performance and emissions of CI (Compression Ignition) engines. The impact of variations of IP on the performance and emission of CI engine fuelled with ternary blends needs fresh investigation. The previous works lack the analysis of high IP variation in diesel engine fuelled with ternary blend that involve higher alcohol. This experimental work aims to investigate the improvement in CI engine performance and reduction in the exhaust emissions by applying varied IP to the engine powered with diesel-jatropha biodiesel-heptanol blends. In this context, four different ternary blends were prepared by varying biodiesel and heptanol contents from 20 to 50 % and 10–40 %, respectively. The ternary blends were tested in a single-cylinder, four-stroke, direct-injection CI engine by varying the IP from 400 to 500 bar at 10 and 20 Nm engine loads while maintaining the engine speed at 1800 rpm. The results indicated that DBOHep20 achieved a maximum reduction of CO and smoke emissions by 57.4 % and 91.6 %, respectively. The lowest NOx emission was achieved by DBHep40 which was found to be 13.27 % lower than diesel. In the case of engine performance, DBHep40 resulted in lowest BSFC and highest BTE which were found to be just 12.5 % higher and 3.9 % lower than diesel, respectively. The lower IP leads to lesser emissions with a slight compromise with engine performance.

Experimental Study on the Performances of a Diesel Engine using Emulsified Diesel at Various Fuel Injection Pressur

Emulsified diesel has been used in a diesel engine at four different fuel injection pressures, i.e., 160 bar, 190 bar, 210 bar and 250 bar to investigate performance as well as emission characteristics of the engine. Brake thermal efficiency is noted to be improved at higher injection pressure and the maximum efficiency is recorded at injection pressure of 210 bar using emulsified diesel which is 3.3% more than that noted using normal diesel. At higher engine load, the neat BSFC considering only the quantity of diesel fuel present in the emulsion is found to be less compared to neat diesel. The emission measure of NOx and smoke are recorded to reduce at higher fuel injection pressure.

Characteristics of a CRDI Engine Fuelled by Waste Transformer Oil with High Fuel Injection Pressure

The impact of fuel injection pressure on the characteristics of the CRDI Diesel Injection system powered by Transesterified Waste Transformer Oil (TWTO) is investigated in this study. It was discovered in a previous experimental study that when transesterified waste transformer oil is utilised as a fuel in a normal diesel engine, the brake thermal efficiency (BTE) is dwindled because of the combustion characteristics of TWTO and its blends. TWTO25 blends shows comparable results to that of convention diesel fuel and higher blends exhibited lower characteristics with standard operational parameters due to their higher viscosity. In light of this, experimental research was conducted in the current study to improve the performance of TWTO25 blend in diesel engines with high fuel injection pressure. The fuel injection pressure is varied from 22MPa to 88MPa to achieve better atomization which intern increases the engine performance. Peak fuel injection pressure exhibits an improvement in brake thermal efficiency of 6.67% compared with neat diesel. In terms of emission attributes, the CO, HC and smoke level continuously tumble down with an upsurge in fuel injection pressure due to the well-atomized spray.

Experimental and computational studies on the effects of reduced fuel injection pressure and spark plug protrusion on the performance and emissions of a small-bore gasoline direct-injection engine

Application of direct injection (DI) technology in small-bore engines, the type used in two- and three-wheelers, could improve their performance significantly. It is recognised that the use of high fuel injection pressure is beneficial in large-bore engines for a good mixture preparation. However, simple systems incorporated with low-pressure DI are desirable in small-engine segment of automobiles. Further, high fuel pressures will result in excessive wall wetting when cylinder dimensions are small. Extensive studies were carried out to investigate the minimum fuel injection pressure required for homogeneous and lean modes of operation in such small bore DI engine. The effect of spark plug protrusion in the combustion chamber was also investigated under the spray-guided configuration. Comprehensive experiments and CFD simulations were performed for estimating the engine efficiency, emissions, mixture preparation characteristics, fuel spray and fuel impingement on combustion chamber walls. Results have demonstrated that engine performance and emissions did not deteriorate when fuel injection pressure was reduced from 150 to 50 bar at full load. However, at very low pressures, like 20–30 bar, THC, CO and smoke emissions increased. Fuel injection pressure did not influence the lean limit, that is, equivalence ratio of about 0.77, but influenced the thermal efficiency at lean conditions. In order to attain high efficiency, under lean conditions, a minimum fuel pressure of 80 bar was required. The spark plug protrusion that resulted in a gap of 0.75 mm with respect to the incoming fuel spray cone has given the best engine performance, while higher protrusions affected the tumble flow and led to the stratification of charge near the spark plug, which resulted in elevated CO and smoke emissions. Hence, this work highlights that relatively lower direct injection pressures are suitable in small bore engines, which will impact the development of cost effective components for such applications.

Multiple fuel injection strategy for premixed charge compression ignition combustion engine using biodiesel blends

In the last decade, advanced combustion techniques of the low-temperature combustion (LTC) family have attracted researchers because of their excellent emission characteristics; however, combustion control remains the main issue for the LTC modes. The objective of this study was to explore premixed charge compression ignition (PCCI) combustion mode using a double pilot injection (DPI; pilot-pilot-main) strategy to achieve superior combustion control and to tackle the soot-oxides of nitrogen (NOx) trade-off. Experiments were carried out in a single-cylinder research engine fueled with 20% v/v biodiesel blended with mineral diesel (B20) and 40% v/v biodiesel blended with mineral diesel (B40) vis-à-vis baseline mineral diesel. Engine speed and rate of fuel-mass injected were maintained constant at 1500 rpm and 0.6 kg/h mineral diesel equivalent, respectively. Pilot injection timings (at 45° and 35° before top dead center (bTDC)) and fuel quantities were fixed, while three fuel injection pressures (FIPs) and four different start of the main injection (SoMI) timings were investigated in this study. Results showed that multiple pilot injections resulted in a stable PCCI combustion mode, making it suitable for higher engine loads. For all test fuels, advancing SoMI timings led to relatively lesser knocking; however, engine performance characteristics degraded at advanced SoMI timings. B40 exhibited relatively superior engine performance among different test fuels at lower FIP; however, the difference in engine performance was insignificant at higher FIPs. Fuel injection parameters showed a significant effect on emissions, especially on the NOx and particulates. Advancing SoMI timing resulted in 20%–50% lower particulates emissions with a slight NOx increase; however, the differences in emissions at different SoMI timings reduced at higher FIPs. Somewhat higher particulates from biodiesel blends were a critical observation of this study, which was more dominant at advanced SoMI timings. Qualitative correlation between NOx-total particulate mass (TPM) was another critical analysis, which exhibited the relative importance of different fuel injection parameters for other alternative fuels. Overall, B20 at 700 bar FIP and 20° SoMI timing emerged as the most promising proposition with some penalty in CO emission.

Investigation of the combustion and particle emission characteristics of a GDI engine with a 50 MPa injection system

The effects of injection pressure and injection timing are investigated in a gasoline direct injection engine with a 50 MPa injection system at part-load operating condition by experimental methods. The engine was invariably operated in stoichiometric air/fuel ratio, 1500 r/min engine speed and 5–15 bar break mean effective pressure (BMEP). The characteristics of combustion, particle size distribution (PSD) and particle number (PN) concentration of the emission are analyzed. The results indicate that delaying the injection timing can suppress the knocking tendency at higher engine loads, and significantly reduce fuel consumption, but the delayed injection increases particle emission. With the fuel injection pressure increased from 35 MPa to 50 MPa, the PN of all particle size segments are significantly reduced. High injection pressure has a significant effect on reducing the accumulation particles, and the PN concentration is reduced by more than 20%. The particles with a diameter of 5–23 nm (sub-23 nm) are a problem that cannot be ignored, which accounts for more than 50% of the total PN emission. A high fuel injection pressure can effectively reduce particulate matter emissions caused by late injection, thereby achieving both fuel consumption and particle emission reduction.

Effects of Biodiesel Fuels Produced from Vegetable Oil and Waste Animal Fat on the Characteristics of a TDI Diesel Engine

In this study, four different biodiesel fuels obtained from corn oil, safflower-rapeseed oil mixture (50%-50% v/v), waste chicken fat, and waste fleshing oil were tested in a six-cylinder, water-cooled, TDI diesel engine. Vegetable oil and waste animal fat origin biodiesel fuels’ effects on the performance, injection, combustion and emission characteristics of test engine were compared with each other and petroleum-based diesel fuel as reference fuel. Biodiesel fuels (regardless of their feedstock) increased in-cylinder gas pressure, brake specific fuel consumption, and NOx emissions while decreased THC and CO emissions compared to pure diesel fuel. In comparison to petro-diesel, the start of fuel injection timing advanced but the end of fuel injection timing retarded with biodiesels. In addition, comparatively higher fuel injection pressure values were attained with all biodiesel fuels. Waste animal fat and vegetable oil origin biodiesel fuels showed similar in-cylinder gas pressures, fuel injection characteristics and brake specific fuel consumption values. However, CO emissions of vegetable oil-based biodiesel fuels were lower and NOx emissions were higher than those of waste animal fat-based biodiesels.

Effects of High-Pressure Two-Stage Fuel Injection on the Diesel Engine Performance in Start Process

Effects of High-Pressure Two-Stage Fuel Injection on the Diesel Engine Performance in Start Process

Optimization of hydrogen‐enriched diesel/n‐Amyl alcohol‐fueled engine to meet emission standards through varying nozzle opening pressure and static injection timing

AbstractImportant injection parameters such as fuel injection timing (FIT) and fuel injection pressure (FIP) on different piston bowl geometries substantially impact the performance, emissions, and combustion characteristics of a common rail direct injection engine. The aim of this study deals with the effects of piston bowl geometry (hemispherical bowl [HSB], troded bowl [TRB], and re‐entrant bowl [REB]), FIP (200, 220, and 240 bar), and variable FIT (20, 24, and 28°bTDC) with hydrogen‐diesel/1‐pentanol (B20) (80% diesel and 20% pentanol) with a constant flow rate of hydrogen at 12 Lpm. Furthermore, to decrease emission standards and energy consumption, biodiesel and hydrogen are the ideal substitutes for conventional fuels. REB outperforms HSB and TRB in terms of brake thermal efficiency (5.67%) and hydrocarbon (8% reduction), increasing the FIP at full load (240 bar). However, with the increase in the FIP in the REB, a slight reduction in nitrogen oxide (NOx) emissions (2%) is observed. With an increase in FIP in the case of REB, net heat release rate, peak pressure (in‐cylinder), and rate of pressure rise all rise significantly by 3.4%, 4.2%, and 2.3%. NOx emissions are marginally enhanced with higher FIP and advanced FIT. It is found that changing the piston shape and FIP simultaneously is a potential alternative for improving engine performance and lowering emissions.

Spray Behaviors and Gasoline Direct Injection Engine Performance Using Ultrahigh Injection Pressures up to 1500 Bar

High fuel injection pressure systems for Gasoline Direct Injection (GDI) engines have become widely used in passenger car engines to reduce emissions of particulates and pollutant gases. Current commercial systems operate at pressures of up to 450 bar, but several studies have examined the use of injection pressures above 600 bar, and some have even used pressures around 1500 bar. These works revealed that high injection pressures have numerous benefits including reduced particulate emissions, but there is still a need for more data on the possible benefits of injection pressures above 1000 bar. This article presents spray and engine data from a comprehensive study using several measurement techniques in a spray chamber and optical and metal engines. Shadowgraph imaging and Phase Doppler Interferometry (PDI) were used in a constant volume chamber to interpret spray behavior. Particle Image Velocimetry (PIV) was used to capture near-nozzle air entrainment. Optical engine experiments were performed to visualize the spray's position relative to the piston at different start of injection (SOI) timings. A single-cylinder GDI engine was used to investigate the effects of injection pressure on emissions and combustion characteristics. The spray tests showed that high-pressure sprays tend to exhibit better atomization and create more air entrainment, accelerating evaporation and mixing. However, high pressures also cause high spray tip penetration due to the high spray velocity, potentially causing wall film formation. At commonly used SOI timings, the benefits of high-pressure injection are relatively insignificant. The improvements in combustion stability and emissions of hydrocarbon (HC) and particulates are greater when the SOI timing is advanced (≈340°bTDC) or retarded (later than 180°bTDC). Wall film occurs at advanced SOI timing for all injection pressures, but high injection pressures significantly reduce particle number (PN) emissions by affecting wall film formation. At late SOI timings, high injection pressures yield acceptable combustion stability and emissions because they shorten the injection and promote mixing. These results suggest that high-pressure sprays allow HC and PN emissions to be greatly reduced and increase flexibility with respect to injection timing without sacrificing engine performance or increasing other emissions. Fuel consumption is also improved, but the effect is more significant when the injection pressure is 1000 bar.

An experimental assessment on the influence of high fuel injection pressure with ternary fuel (diesel‐Mahua methyl ester‐Pentanol) on performance, combustion and emission characteristics of common rail direct injection diesel engine

This paper deals with analysis of the influence of fuel injection pressure with ternary fuel (diesel + Mahua methyl ester + Pentanol) on the emission, combustion and performance characteristics of a four stroke, single cylinder, common rail direct injection diesel engine working at a constant speed and varying operating scenarios. The usage of ternary fuel raised the NOx emission (12.46 %) value and specific fuel consumption (SFC) with a decrease in the BTE (brake thermal efficiency) which attributes to its properties and combustion characteristics. The combustion process was affected by the physical properties of the blended fuel such as volatility and viscosity and this eventually affected the performance of the engine. The fuel injection pressure is varied from 20 MPa to 50 MPa so that ternary fuel can be properly utilized. The high injection pressure of 50 MPa has better combustion characteristics and higher brake thermal efficiency (4.39 %) value than other injection pressure values. A better mixture is formed due to well atomized spray and as a result, the levels of CO (22.24 %), HC (9.49 %) and smoke (7.5 %) falls with the increase in injection pressure.