High-pressure Fuel Injection System Research Articles

Exploring the Benefits of Karanja-Oil-Derived Biodiesel-Water Emulsion as a Potential Fuel for Diesel Engines Operated with High-Pressure Fuel Injection Systems

<div>Biodiesel is a suitable alternative to diesel because of its carbon neutrality, renewability, lubricity, and lower pollutant emissions. However, extensive research indicates higher oxides of nitrogen (NO<sub>x</sub>) emissions with biodiesel. A practical method to combat this problem is utilizing water and biodiesel as emulsions. The effect of biodiesel-water emulsion in high-pressure fuel injection systems is not fully explored in the existing literature. The present study addresses this research gap by utilizing biodiesel-water emulsions in a modified light-duty diesel engine. The governor-controlled injection system was adapted to a fully flexible electronic system capable of high-pressure injection. Unlike other literature studies, the fuel injection timings were optimized with biodiesel-water emulsions to maximize brake thermal efficiency (bte) at every load condition. In a novel attempt, the biodiesel source, i.e., raw Karanja oil (RKO), a triglyceride, was utilized as the surfactant to stabilize the biodiesel-water emulsions containing 6%, 12%, and 18% water. The emulsions reduced the ignition delay and cylinder pressures, with less-intense premixed combustion and a more significant diffusion phase combustion than biodiesel. The emulsions also present a delayed combustion phasing following the injection timing trends. Among the tested emulsions, at 5.08 bar brake mean effective pressure (BMEP), 18% biodiesel-water emulsion resulted in an 18% reduced brake specific fuel consumption (bsfc), 5% increase in bte, 30% and 7% mitigation in NO<sub>x</sub> and smoke levels, with an increase of 10% and 28% for unburned hydrocarbon (HC) and carbon monoxide (CO) emissions.</div>

Prediction of split injection strategy assisted diesel engine combustion, performance and emission characteristics fuelled waste frying oil methyl ester through central composite design

The objective of this study is to use response surface methodology to forecast the performance, combustion, and emission characteristics of an advanced injection strategy-assisted diesel engine running on waste frying oil methyl ester. The experiment was carried out on a diesel engine using a high-pressure fuel injection system. The main injection timing ranges varied from 16 to 24 °CA bTDC, whereas the post-injection ranges from −6 °CA bTDC to 6 °CA aTDC. The injection quantity for the main and post injections quantity varied from 70 % to 90 %, 10 % to 30 %, and the injection pressure is set at 500 bar. Experiments were carried out using a design matrix developed by the design of experiments. At 100 % load, B100-90 %-10 % obtained the highest BTE of 33.87 % and the lowest fuel consumption of 0.268 kg/kW-hr. At the main injection timing of 22 °CA and post-injection timing of −4 °CA, D100-80 %-20 % achieved the lowest unburned hydrocarbon, Smoke emission of 13 ppm, and 1.613 FSN respectively. The point prediction approach was used to forecast the combustion and emission parameters of a diesel engine, and the predicted results were in good agreement with the experimental results. Furthermore, when compared to advance injection timing for biodiesel fuel, retarded injection timing reduces nitric oxide emission. The Split injection strategy is one of the most effective techniques to reduce soot and NO × emissions while maintaining diesel engine efficiency.

A Hybrid Taguchi-Regression Algorithm for a Fuel Injection Control System.

The fuel injection system is one of the key components of an in-cylinder direct injection engine. Its performance directly affects the economy, power and emission of the engine. Previous research found that the Taguchi method can be used to optimize the fuel injection map and operation parameters of the injection system. The electronic control injector was able to steadily control the operation performance of a high-pressure fuel injection system, but its control was not accurate enough. This paper conducts an experimental analysis for the fuel injection quantity of DI injectors using the Taguchi-Regression approach, and provides a decision-making analysis to improve the design of electronic elements for the driving circuit. In order to develop a more stable and energy-saving driver, a functional experiment was carried out. The hybrid Taguchi-regression algorithm for injection quantity of a direct injection injector was examined to verify the feasibility of the proposed algorithm. This paper also introduces the development of a high-pressure fuel injection system and provides a new theoretical basis for optimizing the performance of an in-cylinder gasoline direct injection engine. Finally, a simulation study for the fuel injection control system was carried out under the environment of MATLAB/Simulink to validate the theoretical concepts.

On the origins of lubricity and surface cleanliness in ethanol-diesel fuel blends

Ethanol is the most used bio-derived fuel additive. However, adding ethanol in diesel fuel may negatively impact lubricity or surface cleanliness, which is critical for high-pressure fuel injection systems employed in compression ignition engines. This work investigates surfaces lubricated by ethanol–diesel blends. Adding 5 wt% ethanol in diesel showed negligible changes in fuel lubricity, while blending 10, 20, and 40 wt% ethanol increased wear rates by 46, 81, and 239% respectively. These increases in wear rates (with increases in ethanol by wt%) correlate with the evolution of electrical contact resistance (ECR) values over time. As more ethanol was added, the ECR values signaled thinner fuel films, more metal-to-metal contacts, and a delayed onset of frictional product growth. Raman spectra showed that forming frictional species produced by tribochemical reactions enhanced fuel lubricity. The absence of some frictional species in ethanol lubricated surfaces points to simultaneously improved surface cleanliness and reduced lubricity.

High pressure direct fuel injection as a solution for performance enhancement in two-stroke spark-ignition engine

ABSTRACT Two-stroke spark-ignition engines mainly suffer from the poor fuel economy and high exhaust emission. However, the methodology presented here has adequate potential that can salvage these engines from becoming extinct as the compactness and their power to weight ratio are the two favorable characteristics that provide sufficient leverage for their salvation. The present paper makes an attempt to investigate the influence of the direct fuel injection at moderately high pressure on two-stroke spark-ignition engine performance as well as emission. In this paper, the conventional carbureted two-stroke spark-ignition engine has been modified with a high pressure fuel injection system installed on the cylinder head. The injection of fuel is timed with the closure of exhaust port shut by the piston, which helps in saving fresh fuel from getting short-circuited through the exhaust port. The experimental investigation has been carried out on the engine at various throttle positions of both carburetor as well as fuel injector for different speeds. The experimental measurements revealed that results of direct fuel injection mode compared well as opposed to the carburetor mode. It was observed that brake power exhibited significant improvement approximately 20.1% as compared to the conventional engine. The brake thermal efficiency is found to be 16.3% higher than that of the conventional engine. Above all, fuel loss through short-circuiting noted to have reduced brake specific fuel consumption by 17%. The direct injection system has shown 27.5 and 88.5% reduction in carbon monoxide and unburned hydrocarbons emission, respectively, as compared to the conventional engine.

Influence of high pressure fuel injection system on engine performance and combustion characteristics of Moringa Oleifera biodiesel and its blends

The present investigation studies the effect of advanced injection strategy on diesel engine characteristics fuelled with moringa oleifera biodiesel and its blends. Experiment was carried out on a Common Rail Direct Injection assisted diesel engine under different fuel injection pressure from 300 bar to 600 bar. Similarly, fuel injection timing was varied from 15°CA to 25°CA bTDC. The results showed that maximum brake thermal efficiency of 33.49% was obtained for B20 at higher injection pressure and advanced injection timing. Also, pure biodiesel achieved minimum carbon monoxide and maximum carbon dioxide emission of 0.01% vol. and 9.1% vol. respectively along with minimum unburnt hydrocarbon emission of 3 ppm. The B20 achieved maximum heat release rate of 41.7 kJ/m3°CA which is nearly equivalent to conventional diesel at advanced injection timing and higher injection pressure. But in view of nitric oxide emission, pure biodiesel showed an increasing trend at around 1389 ppm even after advancement of injection timing and injection pressure. Hence, this study revealed that advanced injection strategy along with Moringa Oleifera biodiesel at various percentages of blends reduces the exhaust emissions except oxides of nitrogen which thereby improves the efficacy of the engine. Even though the brake thermal efficiency was obtained maximum for the conventional diesel at standard operating condition, the same can also be achieved with biodiesel blends by increasing the injection pressure higher than that of the level used for conventional diesel.

Numerical simulation of cavitation for liquid injection in non-condensable gas

Modern internal combustion engines rely on a high pressure fuel injection system to deliver the fuel inside the engine. This high pressure fuel injection also results in additional complexities, one of which is the cavitation occurring due to large pressure drops inside the injector. The generation of cavitation pockets inside the injector is known to increase the turbulence locally, affecting the external jet formation. To capture this effect, a specific procedure is needed to study the effect of in-nozzle cavitation on the external jet. In this study, we propose and validate a method to study cavitation as well as the external jet formation using a consistent numerical framework based on interface capturing techniques. This formalism allows the representation of three phases : liquid, air and vapor. Numerical simulations of a cavitating liquid jet for two types of cavitation regimes are presented, namely developing cavitation and super cavitation. Numerical results are compared quantitatively, with the existing experimental measurements from the literature of the velocity field inside the injector, and qualitatively, by comparing the liquid and vapor structures obtained in the experiment and the simulation.

Rail Pressure Estimation for Fault Diagnosis in High Pressure Fuel Supply and Injection System

Engine roughness (ER) is a complex issue in GDI engines and a frequent customer complaint in workshops. Still it is hard to isolate the root cause of the vibration which is received by the driver. The present paper aims to identify the type and extent of faults causing ER that have their origin in the fuel supply and injection system. The method is presented using the injectors as an example, since they have a great impact on engine related vibrations. The injectors affect ER through mixture formation. For example, a deviating amount of injected fuel mass on one cylinder leads to a deviating delivery of work during the combustion cycle and thus causes vibrations.For the investigation additional pressure sensors were installed in the high pressure fuel system to observe the transfer behavior in the hydraulic system. Tests were executed in different reference and fault states, where a fault state is represented by deviating mass flows of an injector. The generated data is used to develop a parameter estimation model, describing the pressure in the fuel rail of the investigated engine.Firstly, a set of reference parameters is generated by a parameter optimization algorithm for each operating point under reference conditions. Then, these sets of parameters are used for initial calibration of the model for the following injector diagnosis. Observing the adaptation of a separate set of diagnostic parameters, allows for a precise pinpointing to a defective injector. It also delivers information about the type of fault and its size. Finally, the results are reconfirmed by executing the diagnosis on data of a healthy system to preclude mis-detections of faults.

Numerical Simulation of Pressure Fluctuation in High-pressure Common-rail Fuel Injection System

In the past several years, the global diesel engine technology has made significant breakthroughs. The diesel engine has a good economy and power. In 20 years or so, the number of diesel vehicles will exceed the trend of gasoline engines. Diesel engine technology is also developing towards low pollution, low fuel consumption, and high power. To improve the performance of diesel engines, the key is to improve the conversion rate of internal energy to mechanical energy and combustion degrees. In the fuel injection system of diesel engines, a high-pressure common-rail with a large volume is often added between the plunger high-pressure fuel pump and the injector. Its function is to save fuel from the plunger fuel pump, to suppress the fluctuation of oil pressure, and to output high-pressure fuel by adjusting the characteristic parameters of the injector. Firstly, the physical model and mathematical model have been established, including the plunger pump, the high-pressure common rail, and the injector. After that, we use the modified Euler method to solve ordinary differential equations by MATLAB programming. Finally, the Optimized working strategies of plunger pump to inject diesel oil into high-pressure common rail have been obtained. In this high-pressure common rail system, cam of the plunger pump spin 1225.67 times a minute, and pressure relief valve is opened automatically when the pressure in high-pressure common-rail is over 103 MPa, so that the pressure in high-pressure common-rail is approximately stable at 100 MPa, and the fluctuation is small.

Design and optimization of a novel electrically controlled high pressure fuel injection system for heavy fuel aircraft piston engine

The heavy fuel compression ignition engines are widely equipped as aircraft piston engines. The fuel injection system is one of the key technologies that determines the performance of engine. One of the main challenges is to precisely control the injected fuel quantity and flow rate in the presence of pressure fluctuation. This challenge is even more serious for heavy fuel. An original design for electrically controlled high pressure fuel injection system called Multi-Pump-pressure-reservoirs fuel injection System (MPS) was demonstrated to reduce the pressure fluctuation and help keep injection stable. MPS was compared with an ordinary high pressure Common Rail fuel injection System (CRS). This work established one-dimensional AMESim and mathematical models for both CRS and MPS to study the effect of different structures and geometric parameters on the pressure fluctuations. The calculations show that the average fuel pressure fluctuation of MPS can be reduced by 57% for the crankshaft speed of 1900 r/min, and the pressure fluctuation before injection reduced by 100%. It is concluded that the pressure performance of MPS is less sensitive to pressure reservoir volume than that of CRS, and there is an opportunity for further volume reduction.

Durability Study of a High-Pressure Common-Rail Fuel Injection System Using Lubricity Additive-Dosed Gasoline-Like Fuel

Durability Study of a High-Pressure Common-Rail Fuel Injection System Using Lubricity Additive-Dosed Gasoline-Like Fuel

Ignition characteristics of straight vegetable oils in relation to combustion and injection parameters, as well as their fatty acid composition

Straight vegetable oils may be a promising alternative to fossil diesel fuel. Fuels to be used in compression ignition engines have to meet several specifications, including the requirement of a certain ignition characteristic. The ignition characteristic is described by the cetane number of a fuel and measured using engine or constant volume combustion chamber device based methods. However, none of these standardized methods is directly applicable for straight vegetable oils. As a result cetane numbers of vegetable oils with the same origin and indicated in literature can vary by several cetane number units. Furthermore, the known cetane numbers of commonly used oils such as rapeseed or soybean oil are lower than that of conventional diesel fuel. In contrast, emission testing of these oils using modern diesel engines under high load conditions indicated an ignition behavior comparable to that of diesel fuel. Thus, the task of this research was to determine the ignition characteristic of nine different straight vegetable oils and two oil mixtures using a constant volume combustion chamber device equipped with a high pressure fuel injection system. The ignition characteristic was provided using primary reference fuel calibration. The calibration was done at different combustion chamber temperatures and injection pressure levels representing various engine load conditions. The determined ignition characteristics were expressed in terms of an estimated cetane number of vegetable oils (ECNO). In contrast to conventional diesel fuel, the ECNO of vegetable oils was found to be strongly influenced by both, combustion chamber temperature and injection pressure. With rising temperature and injection pressure, the ECNO was observed to increase and exceed that of diesel fuel for certain vegetable oils. Thus, it was recommended to use two ECNO to provide a meaningful definition of the ignition characteristic of vegetable oil fuels. One should reflect the ignition characteristic at low load engine points and was determined with an injection pressure of 500bar and a combustion chamber temperature of 852K. The other one should be valid for intermediate and high engine load conditions. This was determined using an injection pressure of 1000bar at a temperature of 923K. A high linear correlation could be found between the degree of saturation of the fatty acids present in the oils and their ECNO. The ECNO was higher for oils with a low amount of monounsaturated and especially polyunsaturated fatty acids.

Research on Software Framework and Validation of a High-pressure Fuel Injection System

Programmable logic devices (PLDs) and their software have found extensive application in communication and electrical devices. It seems difficult to conduct test on the performance and functions of device circuit before it is formed. During PLD software test, test cases of standard interfaces, including clock frequency, are hard to reuse, which would cause reduced testability of PLD software. In order to solve problems of poor reusability, low efficiency and scalability, this paper studied the reusable PLD device software test technology, made an regression analysis of typical PLDs and defects and proposed judgment basis applicable to the test methods, procedures and results for embedded PLD device software[1].

Research on Software Framework and Validation of a High-pressure Fuel Injection System

Research on Software Framework and Validation of a High-pressure Fuel Injection System

Novel dual fuel diesel-ammonia combustion system in advanced TDI engines

As ammonia (NH3) is the best hydrogen carrier for safety and efficiency, transportation engines have been proposed using ammonia. NH3 may be used as a single combustion fuel for an internal combustion engine. However, as NH3 is a difficult fuel for what concerns combustion, faster and more complete combustions may be achieved by working dual fuel. The most promising alternatives are offered by using either diesel injection ignition plus port/direct injection of the NH3, or jet ignition of a gasoline-like fuel (gasoline, CH4, C3H8, H2) plus port/direct injection of the NH3. The opportunity of diesel injection ignition plus direct injection of NH3 is considered here. The simulations show the prospect to achieve Diesel-like power densities and efficiencies, and load control by quantity of fuel injected. Critical component for prototyping is the high pressure fuel injection systems specifically developed for NH3.

An experimental and numerical analysis of pressure pulsation effects of a Gasoline Direct Injection system

Downsized, turbocharged GDI engines are considered as the most effective system architecture car makers can implement to meet stricter CO2 production and pollutant emissions regulations. Moreover, the GDI engine is accounted to be the ideal thermal part of hybrid powertrains which will play a more and more significant role to meet future CO2 and emissions standards. Hence in the last years significant research efforts are being applied to the development of GDI technology in order to optimize its performance in terms of specific fuel consumption and emission control capabilities.These engines require an extremely reliable high pressure fuel injection system to allow advanced combustion strategies and to improve the fuel atomization process and the air–fuel mixing. Nevertheless, in these installations intense fuel pressure fluctuations may occur due to continuous pumping and injection events, possibly causing low precision in the fuel metering from cylinder to cylinder and relatively poor spray quality. For this reason the injection system design must be supported by accurate computational models able to predict the actual injector flow and the whole fuel system behavior.This paper describes a combined 1-D numerical and experimental analysis of a complete GDI injection system with a particular focus on the waves propagation phenomena and their dependence on the system geometry, such as high pressure pipe length and internal diameter, rail inlet position, flow-restrictor diameter.The numerical code was validated through the comparison of the predicted results with experimental data, mainly pressure and instantaneous injected flow rate measured by a hydraulic test bench (named Wet-System) developed at SprayLab – University of Perugia, which consists of the high pressure pump, the pipes, the fuel rail and injectors so to simulate the complete injection system operation. The injection-system mathematical model was then used to predict the system dynamic response in operating conditions beyond the test bench limits, paying specific attention to the flow-restrictor effect. Finally, the model capability in accurately predicting the waves dynamics effects on the injected fuel flow rate and mass was assessed for multi-injection strategies, when the dwell time between consecutive injections is varied.

A Study of Knock Improvement of Direct Injection Gasoline Engines Using High-Pressure Fuel Injection System

A Study of Knock Improvement of Direct Injection Gasoline Engines Using High-Pressure Fuel Injection System

3-way형과 Bypass형 서보유압 피에조 인젝터의 구동특성 비교

CRDi technology of diesel engine was developed from in the early 2000s due to a need to increase fuel efficiency and environment care. Especially, high-pressure fuel injection system in CRDi system which has a fuel injection unit including an injector, a fuel pump and common-rail, etc. becomes possible to make the exhaust gas clean as well as power improvement. In this study, comparison of dynamic characteristics of servo-hydraulic piezo-driven injector with 3-way and bypass-circuit type was analyzed by using the AMESim code. As results of this study, it found the bypass-circuit inside servo-hydraulic piezo injector can cause a faster injection response than that of the 3-way type. Also it was shown that bypass-circuit type had better control capability due to hydraulic bypass system.

Spray and atomization of diesel fuel and its alternatives from a single-hole injector using a common rail fuel injection system

Fuel spray and atomization characteristics play an important role in the performance of internal combustion engines. As the reserves of petroleum fuel are expected to be depleted within a few decades, finding alternative fuels that are economically viable and sustainable to replace the petroleum fuel has attracted much research attention. In this work, the spray and atomization characteristics were investigated for commercial No. 2 diesel fuel, biodiesel (FAME) derived from waste cooking oil (B100), 20% biodiesel blended diesel fuel (B20), renewable diesel fuel produced in house, and civil aircraft jet fuel (Jet-A). Droplet diameters and particle size distributions were measured by a laser diffraction particle analyzing system and the spray tip penetrations and cone angles were acquired using a high speed imaging technique. All experiments were conducted by employing a common-rail high-pressure fuel injection system with a single-hole nozzle under room temperature and pressure. The experimental results showed that biodiesel and jet fuel had different features compared with diesel. Longer spray tip penetration and larger droplet diameters were observed for B100. The smaller droplet size of the Jet-A were believed to be caused by its relatively lower viscosity and surface tension. B20 showed similar characteristics to diesel but with slightly larger droplet sizes and shorter tip penetration. Renewable diesel fuel showed closer droplet size and spray penetration to Jet-A with both smaller than diesel. As a result, optimizing the trade-off between spray volume and droplet size for different fuels remains a great challenge. However, high-pressure injection helps to optimize the trade-off of spray volume and droplet sizes. Furthermore, it was observed that the smallest droplets were within a region near the injector nozzle tip and grew larger along the axial and radial direction. The variation of droplet diameters became smaller with increasing injection pressure.

Development and performance assessment of the new-generation CF fuel injection system for diesel passenger cars

An innovative hydraulic layout for high-pressure fuel injection systems has been developed. The rail has been removed from the high-pressure circuit of standard Common Rail injection apparatus in order to have: reduced production costs, easy installation on the engine and a fast dynamic response of the injection system during engine transients. The innovative high-pressure pump has been machined with extra delivery ports in order to obtain direct connection with each of the injector feeding pipes. A special pump delivery-chamber, featuring an adequate volume, was designed to provide the minimum hydraulic capacitance required for a proper control of the high-pressure in the system. A prototype of the new-concept Common Feeding (CF) injection system was set up at the Politecnico di Torino laboratory and subjected to an extensive experimental campaign on an advanced hydraulic test rig. The hydraulic performance of the new apparatus was compared with that of standard Common Rail system, in terms of injected flow-rate time histories, cycle-to-cycle dispersion and multiple injection dependence on dwell time. Finally, the new-generation system was installed on a Euro 5 diesel engine and tested in a dynamometer-cell. Pollutant emissions were measured at some reference working conditions as well as along the NEDC and compared to analogous data obtained for the same engine, but set up applying the standard Common Rail.