Number Of Nozzle Holes Research Articles

Compensation for the differences in LHV of diesel-OME blends by using injector nozzles with different number of holes: Emissions and combustion

The reduction of particulate matter (PM) emissions has become a major topic in the development of compression ignition (CI) engines. The aftertreatment of exhaust gases by means of particulate traps (DPF) has given promising results in terms of effectiveness. However, the backpressure and necessity to regenerate causes an increase in fuel consumption and operational cost. A possible strategy to reduce this cost is the abatement of PM levels of engine out exhaust gases by employing oxygenated fuels. This solution reduces the backpressure in the exhaust as well as fuel expensive regeneration events. In the present work the performances, in terms of combustion and emissions, of two different blends composed of diesel and a mixture of polyoxymethylene dimethyl ether (OME, POMDME or PODE) were investigated in a single-cylinder, direct injection, 4-stroke, heavy duty diesel engine. In order to minimize the influence on combustion characteristics (i.e. ignition delay, premixed and diffusion combustion portion, etc.), the compensation for the smaller caloric value of the blends in comparison to diesel was performed with an increased number of injector nozzles holes. This strategy was chosen to avoid effects on emissions caused by a prolonged duration of injection, increased fuel pressure or increased nozzle diameter. In total three different number of nozzle holes were tested with a reference diesel case (7-hole) and two with according blends (8-hole, ca. 22% OME; 9-hole, ca. 42% OME). The results show an acceleration of the diffusion combustion rate and the resulting improvements in the indicated specific fuel consumption (−5.7%) with increasing OME portion. In addition, mainly due to a reduction of up to 90% of the soot emissions, the NOx-soot trade-off improved as well. The NOx emissions showed decreased values for the less oxygenated, and increased values for the stronger oxygenated blend. This behaviour is attributed to the faster combustion, which, on the one hand reduces the residence time to form NOx and on the other hand increases the temperature, which enhances NOx formation again. The investigation of the trade-off between shorter residence time and higher temperature can only be performed with constant injection parameters (injected energy, fuel pressure and duration of injection) among the different fuels.

Combined effects of fuel injection pressure and injector nozzle holes on the performance of preheated palm oil methyl ester used in a diesel engine

This paper presents the impact of preheated palm oil methyl ester) (POME) properties and examines the consequences of varying fuel injection pressure (IP), fuel injection timing (IT) and injector nozzle hole number (IJNHN) for improving the combustion quality in a diesel engine, by evaluating the performance parameters, combustion characteristics and emissions. The fuel IPs changed from 188 to 224 bar (with an increment of 12 bar) at fuel ITs 19°, 23° and 27° Before Top Dead Center (BTDC) with a variation of IJNHN (3–5) each 0.3 mm in diameter. The test results revealed that the kinematic viscosity and density of POME decreased slowly with an increase in fuel temperature. At 114 °C, the viscosity and density of POME decreased to close to that of diesel fuel. Preheating POME improved engine brake specific fuel consumption (BSFC), brake thermal efficiency (BTHE) and emissions of CO and Hydro Carbon (HC), with a slight increase of NOx. The results indicate that increased fuel IP of 212 bar and an advanced IT of 27° BTDC with a four-hole IJNHN for preheated POME (114 °C) was the best combination for overall improvement in BSFC and BTHE with reduced emissions (of CO and HC) with respect to baseline diesel.

Hole number effect on spray dynamics of multi-hole diesel nozzles: An observation from three- to nine-hole nozzles

For the simplicity of optical diagnostics, studies on fuel spray and combustion characteristics of modern diesel engines have been conducted using the investigation nozzles having the reduced number of holes (two- or three-hole nozzles) compared to the production nozzles. However, the similarity of spray dynamics between the investigation nozzles and production nozzles has not been confirmed yet. Also, the hole-number effect on spray dynamics has been investigated only in a limited range of hole number making it difficult to derive the clear trend and understandings of the hole number effect. In this study, the hole-number effect on spray dynamics of multi-hole diesel nozzles has been investigated in a wide range of hole number with sufficient data points (three, five, six, eight, nine-hole) by using the X-ray Phase-Contrast Imaging technique. The non-linear trend in the spray structure, as well as the dynamics results, was observed as increasing the hole number regardless of injection pressure. Discussions were made accordingly to understand the observed result trend. The study suggests that great attention is needed when deciding the number of nozzle holes for the optimized engine combustion.

Efficacy of using oxygen microbubble device for facultative anaerobe removal.

Patients with serious gingivitis or periodontal diseases suffer from receding gums. Brushing teeth with a toothbrush may result in bleeding gums and new wounds, which increases the difficulty of removing facultative anaerobes from gum pockets, to decrease the damage inflicted on gums, this study proposed a cleaning device that can generate and emit oxygen microbubbles for eliminating facultative anaerobes in the mouth cavity. In this study, the authors conducted simulations with a denture to investigate the efficacy of using this method to remove facultative anaerobes. In this research for the optimal device design, several variables were manipulated including rotation speeds of the bubble generator, different nozzle diameters, and different numbers of nozzle holes. The results revealed that the device is effective in removing facultative anaerobes; moreover, of all design variables, the number of nozzle holes was the factor having the largest effect on anaerobe removal, as it influenced the flow volume and oxygen content of the discharge: the greater the number of nozzles, the greater the flow volume, oxygen content, and efficacy of anaerobe removal.

Automatic macroscopic characterization of diesel sprays by means of a new image processing algorithm

A novel algorithm is proposed for the automatic segmentation of diesel spray images and the calculation of their macroscopic parameters. The algorithm automatically detects each spray present in an image, and therefore it is able to work with diesel injectors with a different number of nozzle holes without any modification. The main characteristic of the algorithm is that it splits each spray into three different regions and then segments each one with an individually calculated binarization threshold. Each threshold level is calculated from the analysis of a representative luminosity profile of each region. This approach makes it robust to irregular light distribution along a single spray and between different sprays of an image. Once the sprays are segmented, the macroscopic parameters of each one are calculated. The algorithm is tested with two sets of diesel spray images taken under normal and irregular illumination setups.

Numerical and experimental investigations of new nozzle concepts for diesel injectors

The impact of diameter and shape changes of diesel injector nozzles on the internal flow and spray behavior is numerically investigated and compared to the experimental data obtained with new nozzle designs. The diameter was varied between 70 and 130 µm and the number of nozzle holes increased from 8 to 14. Furthermore, new nozzle hole concepts were investigated which feature different diameters in one hole circle (6 + 6 hole nozzle). A diameter ratio of 1.3 and of 2 was applied. The reduction in the spray hole diameter led to a reduction in the mass flow of the nozzle and to a diminished spray penetration. Using the 6 + 6 hole nozzle with a ratio of 1.3, very similar penetration depths were seen for both injection holes despite the different diameter. An increase of the diameter ratio or a design change of the smaller nozzles leads to the desired effect that the spray of the smaller nozzles shows significant smaller penetration depths than the one of the bigger holes.

Experimental study effect of diameter and number of spray nozzle holes on counterflow cooling tower to improve cooling effectiveness

The cooling system is an essential part of the production process within the plant. In the cooling system using cooling tower, efficiency can be improved by increasing the effectiveness of cooling through nozzle modification. This study aims to determine the effect of diameter and number of nozzle holes on cooling effectiveness. The data were taken from the experiments using prototype of counterflow cooling tower with dimension of high x cross-sectional area are 120 cm x 40 cm x 40 cm. Diameter varied by 1; 1.5; and 2 mm, while the number of nozzle holes 4; 8; 16. The results show that the highest cooling effectiveness was achieved at nozzle diameter 1.5 mm with the number of holes 8 that is 38.77%.

Modeling a fuel injector for a two-stroke diesel engine

This paper discusses the modeling of a fuel injector to be applied in a two-stroke diesel engine. A one-dimensional model of a diesel injector was modeled in the AVL Hydsim. The research assumption is that the combustion chamber will be supplied with one or two spray injectors with a defined number of nozzle holes. The diameter of the nozzle holes was calculated for the defined options to provide a correct fuel amount for idling and the maximum load. There was examined the fuel mass per injection and efficient flow area. The studies enabled us to optimize the injector nozzle, given the option of fuel injection into the combustion chamber to be followed.

Eccentric needle motion effect on near-nozzle dynamics of diesel spray

The eccentric needle motion has been regarded as an important cause of in-nozzle flow disturbances and hole-to-hole spray variations of modern fuel injectors. However, the experimental investigations on this subject have rarely been reported due to great difficulties in the direct measurements of eccentric needle motion and the flow characteristics of individual holes in an injection nozzle. In this study, the axial and eccentric needle motion and the near-nozzle spray dynamics of 3-hole, 5-hole and 8-hole diesel injection nozzles were investigated in varied injection pressure conditions using an X-ray phase-contrast imaging technique. The eccentric needle motion and near-nozzle spray axial velocity showed temporal oscillations during the injection with different oscillation frequencies. The frequencies of these two oscillations were independent to the nozzle hole number and injection pressure. To discuss the mutual dependency of these two oscillations, the time traces of the spray axial velocity were measured for individual holes. The results showed that the oscillation phase, frequency and amplitude of the spray axial velocity were almost identical for all holes, which indicated that the sac pressure variation rather than hole-to-hole flow variation can be the primary cause of the spray axial velocity oscillation by the eccentric needle motion. The adequacy of this consideration was thoroughly discussed using a mass balance model in the nozzle sac that predicted the sac pressure variation during an injection event.

The theoretical investigation on influence the fuel spray geometry on the combustion and emission characteristic of the marine diesel engine

The paper presents an analysis of the influence of the fuel spray geometry on the combustion and emission characteristic of the marine 4-stroke Diesel engine. Presented analysis was prepared based on computational fluid dynamic model (CFD). Initial and boundary conditions of the model as well as data used to model validation were collected during the laboratory study. Calculations were conducted for two different fuel injectors with changed nozzle holes diameters, the number of nozzle holes and the angle between holes axis. The increase of the fuel nozzle holes diameter causes the decrease of the fuel spray tip penetration, but simultaneously the decrease of holes number causes that auto-ignition delay is not changed. The increase of the angle between holes axis from 150° to 158° causes fuel ingintion near cylinder head wall. Result of this is the increase of CO fraction. The deterioration of fuel combustion causes the decrease of NOx mass fraction in the cylinder also.

Experimental investigation on performance, emission behavior and exergy analysis of a variable compression ratio engine fueled with diesel - aegle marmelos oil - diethyl ether blends

The intention of the prevailing effort is in the direction of experimentally look for the combined outcome of compression ratio and a number of nozzle holes on performance and emissions of a compression ignition engine by means of an emulsion fuel obtained from aegle marmelos (Bael) oil. This exertion consists of the exergy examination of compression ignition engine towards maximizing the work availability and decreasing the destroyed availability. Ternary blends of diesel - aegle marmelos – diethyl ether (DEE) within the proportion as percentages 100:0:0 (D), 70:20:10 (B1), 60:30:10 (B2), 50:40:10 (B3) became tested in a variable compression ratio (VCR) engine. When operating the diesel engine with B2, Brake thermal efficiency (BTE) of the engine is better by 4.3%, nitric oxides (NOx) emission has been reduced 3.9% at 100% load in compression ratio (CR) 17.5 with number of nozzle hole (NH) 5. The exergy efficiency of B2 fuel has been found 63.88% of fuel input at CR17.5 with 100% engine load. Increasing the number of nozzle holes improves the performance of the diesel engine fueled with bael blends in terms of reduced brake specific energy consumption (BSEC), increased BTE and reduced emissions like hydrocarbon (HC), carbon monoxide (CO) and smoke.

Effect of Injection Location and Multi-Hole Nozzle on Mixing Performance in a CNG-Fuelled Engine with Port Gas Injection, Using CFD Analyses

A compressed natural gas injection device with moving-coil electromagnetic linear actuator and mushroom type poppet valve was designed to supply a large-bore intake port injection type engine with sufficient fuel timely. The transient engine CFD model combined with the poppet valve's motion was established to research the effect of injection conditions on the mixing homogeneity in the intake port and cylinder. Computed penetration distances of impinging jet with different k-e models and different wall functions are compared with measured results in the literature to validate the model. It was observed that the gas injection location and number of nozzle holes have a significant effect on mixing performance both in the intake port and cylinder.

Ultrafast X-ray study of multi-hole GDI injector sprays: Effects of nozzle hole length and number on initial spray formation

Nozzle hole design factors, such as length, diameter, position and number of nozzle holes, significantly alter the near-field jet flow and following spray formation of fuel injection nozzles. This study investigates the effects of various nozzle hole design factors on near-field jet flow and spray formation of the multi-hole injectors for gasoline direct-injection (GDI) engines. The novelty of this study lies in intensive analysis in the near-field jet breakup, dynamics and droplet formation process that have rarely been characterized from previous studies by exploiting the potentials of synchrotron X-ray for near-field spray analysis. Among several nozzle hole design factors, the effects of the length and number of nozzle holes are investigated in the current paper as the first part. Four prototype injection nozzles, which have different lengths and numbers of nozzle holes with a substantially low needle lift of 35μm, were used for this fundamental study. Single- and multi-exposed X-ray phase-contrast images were used to characterize the jet breakup, dynamics and droplet formation process from the nozzle exit to 30mm downstream. The emerging jet flows from the multi-hole GDI injectors were highly turbulent and perturbed immediately from the nozzle exit. The decrease in nozzle hole length increased the axial and radial flow velocity of the emerging jet flow with an increased void fraction inside the nozzle hole at the nozzle exit. It promoted the jet breakup with formation of smaller and more circular liquid ligaments/droplets in the near-field when the nozzle hole length decreased, which accompanied the higher velocity decrease rate and turbulence strength along the spray axis. On the other hand, the increase in the number of nozzle holes decreased the axial and radial flow velocity of the emerging jet flow. It led to a slower breakup of the jet flow with a lower velocity decrease rate along the spray axis at larger number of nozzle holes.

Effect of injector configurations on combustion and emissions in a gasoline direct-injection compression ignition engine under low-load conditions

The effect of injector configurations on combustion and emissions is investigated at low-load conditions in a gasoline direct-injection compression ignition engine. A total of five injectors with higher number of nozzle holes (10, 14) and narrow injection angles (70°, 100°) were tested while comparing with the baseline injector with eight holes and injection angle of 146°. Diesel combustion was also performed at similar operating conditions for the comparison with gasoline combustion. First, at the idle operation (engine speed = 800 r/min, engine load = 10%), combustion stability was very low with baseline injector due to the excessive mixing process. The narrow injection angle was helpful to enhance combustion stability, attributed to suppressing the formation of over-lean mixture by the fuel stratification within narrow area. However, higher number of nozzle holes were unfavorable with frequent misfires by excessive fuel/air mixing. Second, at the low-load operation (engine speed = 1200 r/min, engine load = 25%), combustion and emissions were investigated according to the injection timing. For all injectors, partially premixed compression ignition combustion was realized with early injection which exhibited low nitrogen oxide emissions resulted from lean premixed combustion. However, high hydrocarbon and carbon monoxide emissions were produced with wide injection angle due to the over-mixing and trapped fuel in squish and crevice volume. Hydrocarbon and carbon monoxide emissions were significantly reduced with narrow injection angle, attributed to the fuel stratification inside piston bowl. On the other hand, hydrocarbon and smoke emissions were aggravated in diesel combustion with narrow injection angle, attributed to fuel-rich mixture resulted from the significant fuel impingement on piston bowl. Fuel impingement occurred for both gasoline and diesel; however, evaporation process was much slower for diesel fuel due to the lower volatility. Significant pool fire and rich combustion were observed for diesel combustion, while blue chemiluminescence was dominated in gasoline combustion which meant well-premixed combustion.

Effect of Number of Injector Nozzle Holes on the Performance, Emission and Combustion Characteristics of Honge Oil Biodiesel (HOME) Operated DI Compression Ignition Engine

This paper aims to present the inferences of the experimental studies on the performance, emission and combustion characteristics of Honge oil methyl ester (HOME) as a fuel for a single-cylinder direct injection diesel engine using response surface methodology (RSM) based mathematical modeling which are developed taking 27 set of experimental results. Experiments were carried out to study the effects of compression ratio, injection pressure and injection timing on performance characteristics like brake thermal efficiency (BTE), emissions such as smoke, hydrocarbon (HC), carbon monoxide (CO), nitric oxides (NOx) and combustion characteristics, namely, peak pressure and heat release rate (HRR) in a diesel engine using 3 and 4 hole injectors. The experiments were planned as per full factorial design (FFD) and RSM based quadratic models were developed to establish the relationships between the process parameters and the proposed characteristics. The response surface analysis based on the experimental results reveal that by retarding the injection timing (IT), increasing the injector-opening pressure (IOP) as well as the compression ratio would lead to increased BTE and reduced emissions. Increasing the number of nozzle holes improves the performance of diesel engine fueled with HOME in terms of increased BTE, reduced emissions like smoke, HC, CO and increased peak pressure and HRR. However, NOx emission increases with increased number of holes.

고압 인젝터의 노즐 홀 수가 DME 연료분무의 미립화 특성에 미치는 영향

Abstract This paper presents effect of nozzle hole number on atomization characteristic of DME fuel spray using three different typeof injector having the hole number of 6, 7 and 8. For this study, PDPA(phase Doppler particle analyzer) experiment was per-formed in terms of T ASOE under various injection pressure. To compare general trend of atomization characteristic, the lawdata were ensemble averaged based on T eng of 0.2 ms. Results showed that the droplet diameter in terms of SMD(SauterMean Diameter) was reduced as increase in injection pressure. Increasing the number of hole lead to reduce in droplet diam-eter, but no significant reduction in diameter was observed between hole number of 7 and that of 8. In addition, increasingthe number of hole resulted in decrease in droplet velocity which is considered as the effect of reduction in spray momentumdue to decreasing of fuel quantity per each hole. 기호설명 SMD : 사우트 평균 입경P inj : 연료 분사 압력P amb : 분위기 압력T eng : 통전시간T ASOE : 분사 후 통전 시간 1. 서론

The effects of the combustion chamber geometry and a double-row nozzle on the diesel engine emissions

This paper presents how injector nozzle distributions and the combustion chamber geometry affect the emission characteristics of diesel engines. The number of nozzle holes was increased from seven to 12 by a using double-row nozzle distribution to enhance the air–fuel mixing and the spatial distribution of the spray while avoiding spray overlap. The combustion chamber geometry was modified to have a wide shallow two-step bowl, which ensured adequate spray penetration with the double-row nozzle, to observe the influence of the spray–piston interaction on the combustion and emissions. Three hardware combinations (a seven-hole single-row nozzle with a conventional piston, a 12-hole double-row nozzle with a conventional piston, and a two-step piston) were tested in a single-cylinder direct-injection diesel engine under three boost and exhaust gas recirculation conditions. The injection timing was adjusted to result in a similar power by maintaining 50% of the total fuel mass fraction burned points for each hardware combination. For a conventional boost pressure (1.10 bar) and 30% exhaust gas recirculation, the 12-hole double-row nozzle with a conventional piston exhibited the best emission characteristics with a significant reduction in the particulate matter emissions. For a high boost pressure (1.30 bar) and 30% conventional exhaust gas recirculation, the nitrogen oxide emissions slightly increased and the particulate matter emissions decreased for the 12-hole double-row nozzle with a conventional piston compared with those for the seven-hole single-row nozzle. The two-step piston resulted in decreased particulate matter emissions but increased nitrogen oxide emissions under a high boost pressure. For 60% high exhaust gas recirculation, which is characterized by low-temperature combustion, the particulate matter emissions, the carbon monoxide emissions, and the total hydrocarbon emissions decreased simultaneously without an increase in the nitrogen oxide emissions using the 12-hole double-row nozzle with a two-step piston.

A study of combustion and emissions characteristics of a compression ignition engine processes using a numerical tool

Experimental analysis of a diesel engine gives only the global picture of the in-cylinder processes, through averaged quantities. These averages are sometimes global averages or in some cases taken at each crank angle. To understand the in-cylinder processes better, the distribution of scalars becomes very important. In this paper, Converge, a CFD-tool was used to simulate the closed cycle in-cylinder process of a diesel engine to develop deeper insights into the effects of various injection parameters and compression ratio on engine performance and exhaust emissions. Results from Converge CFD-tool have been validated against the experimental data published in the literature. Effects of compression ratio, number of injector holes, spray angle, half cone angle and injection duration were studied using the validated model. Simulation results indicate that decreasing compression ratio resulted in a significant reduction in NO concentrations with a slight increment in specific fuel consumption (SFC). A narrow spray angle resulted in a considerable reduction of soot and SFC. Spray-to-spray interaction was increased with increasing number of nozzle holes. As a result, higher SFC, CO and soot were observed with increasing number of nozzle holes. Various in-cylinder contour plots showed that the injection with higher injection duration i.e. lower injection pressure produces relatively lower extent of fuel wall wetting and hence resulted in less intensity flames close to the piston head. Increasing the spray angle, number of holes and injection duration resulted in clear decline in exhaust NO concentration.

Research on Simulation of Urea-SCR Injection System for Marine Diesel Engine

The mixing degree of ammonia and exhaust gas has significant effect on the NOx conversion efficiency of SCR (selective catalytic reduction) system. It is essential to investigate the structure of urea nozzle since it considerably impacts the atomization of urea water solution. This paper simulated the process of urea spray by the software FIRE and analyzed the influence of spray characteristics such as nozzle hole number, nozzle hole chamfering as well as the spray angle on the atomization of urea water solution. Simulation results can indicate the optimal nozzle for a certain circumstance which is beneficial to the engineering design.

고압 디젤 인젝터 노즐 홀 수가 연료 분무 및 배기 특성에 미치는 영향

This paper This paper presents effect of nozzle hole number on spray characteristics and engine performance. Experiments were conducted to measure spray penetration and SMD distributions using a spray visualization system and PDPA (phase Doppler particle analyzer) system. In addition, engine performance and emission characteristics were measured using a single cylinder engine and emssion measurement systems. Results showed that 8-hole-injector exhibits improved spray performances. Furthermore, soot emission was decreased with 8-hole-injector, compared to that of 6-hole-injector.