Number Of Nozzle Holes Research Articles

Simulation and experiment on improving NOX conversion efficiency of ship selective catalytic reduction system

Selective catalytic reduction (SCR) technology is the main means of reducing NOX emissions. Urea injection structure parameters (i.e., the hole number in a nozzle, spray angle, the distance between the nozzle and the front section of the catalyst) and operating parameters (i.e., exhaust gas temperature, gas hourly space velocity, ammonia-to-nitrogen ratio (ANR)) of the SCR systems have a significant impact on denitrification efficiency (deNOX). A three-dimensional simulation model is developed to investigate the impact of diverse parameters on deNOX. The influence of temperature, ANR and space velocity on the deNOX of SCR system is studied by using the control variable method. The simulation model is modified according to the SCR catalyst gas distribution test results. A diesel bench experiment is conducted to test the deNOX of the SCR system of D2 cycle and two additional operating points to verify the accuracy of the numerical simulation model. Based on this model, the influence of key factors on the deNOX of SCR system is studied. In SCR system, the optimal urea injection angle is about 75°, the optimal number of nozzle holes is 4, the distance between the optimal urea injection point and the front section of the catalyst is 8 times of the pipe diameter, and the optimal operating temperature is 300 ∼ 420℃. The influence trend of ANR on deNOX at different temperatures is obtained. This provides a theoretical support for the realization of SCR system in the future.

Effects of Nozzle Diameter and Holes Number on the Performance and Emissions of a Gasoline Direct Injection Engine

The goal of the current study is to estimate how a gasoline direct injection (GDI) engine's performance and emissions are affected by the fuel injector nozzle diameter and hole number of its injectors. A thermodynamic mathematical modelling has been created utilizing a software program written in the MATLAB language to simulate the two-zone combustion process of a four-stroke direct injection engine running on gasoline at (Rotation Engine Speed 3000 revolution per minute (rpm), 40 MPa injection pressure, compression ratio 9.5, and spark timing 145°). The first law of thermodynamics, equation of energy, mass conserving, equation of state, and mass fraction burned were all used in the creation of the software program. The study was carried out at five different nozzle diameters (0.250, 0.350, 0.450, 0.550, and 0.650 mm) and nozzle hole numbers (4,6,8,10,12). The results show that the GDI engine's performance and emissions are significantly influenced by variations in nozzle hole diameter and number. It was shown that engine power, heat transfer, cylinder pressure, and temperature increased with increasing nozzle hole diameter and number of nozzle holes and the maximum value was seen with nozzle hole diameter 0.650 mm and (12) holes. The lowest value for the nozzle hole diameter and number of holes was found to be 0.250 mm and 4 nozzle holes, which resulted in the lowest emissions of carbon monoxide CO and nitrogen monoxide NO. The study was also conducted for different operating conditions (Rotation Engine speed of 1000, 2000, 3000, 4000, 5000 rpm ,35 MPa injection pressure , compression ratio of 11.5 , and spark timing of 140° ) and the same nozzle diameters and nozzle holes number mentioned previously to estimate the maximum values for temperature, pressure, power , heat transfer and emissions . The results of the second part of the study showed that the highest of maximum values of temperature, pressure, and emissions were at of 1000 rpm, a nozzle diameter of 0.650 mm, and (12) holes. The highest values for maximum power at 4000 rpm, a nozzle diameter of 0.650 mm and (12) holes, while the highest maximum values for heat transfer are at 5000 rpm, a diameter of 0.65mm and (12) holes.

A numerical investigation of injector hole configuration and injection parameters in a dimethyl ether fueled DICI engine

AbstractThe lower calorific value of dimethyl ether (DME) is approximately 65% of that of diesel; therefore, a higher quantity of DME must be supplied per cycle to generate the same magnitude of power. A retrofitted DME‐fueled engine generally uses a longer fuel injection duration to provide the excess fuel mass. The present work seeks to find the most appropriate way to increase the mass flow rate of a DME‐fueled direct‐injected compression ignition engine by varying the number of nozzle holes, nozzle hole diameter, and injection pressure. The results show that increasing mass flow rate increases peak combustion pressure and heat release rate but decreases combustion duration. Increasing the number of injector holes increases indicated specific fuel consumption (ISFC) and exhaust emissions (NOx, HC, and CO) due to mixing between unburned fuel spray and neighboring combustion products. Increasing the nozzle hole diameter or fuel injection pressure increases spray tip penetration and improves fuel‐air mixing before combustion initiates. Increasing the nozzle hole diameter by merely 22 μm than the baseline injector reduces ISFC and exhaust emissions at a slightly retarded start of injection (SOI). However, the lowest ISFC was found at the 30 MPa injection pressure at the most advanced SOI, at the expense of higher NOx.

Hole number effect on internal and discharged flow characteristics of diesel injector during transient operation

Selecting the proper number of nozzle holes is a critical matter to achieving optimal combustion in diesel engines. In recent years, short transient injections with ultra-high injection pressure have been adopted in diesel engines to achieve cleaner combustion but the effect of hole number on this transient diesel injection has not been thoroughly investigated. The current study performs an experimental observation of discharged flows from diesel injectors during transient operation using the X-ray phase-contrast imaging technique for six multi-hole injectors (three-, five-, six-, eight-, nine- and ten-hole). The observation results showed that discharged flows varied without any distinctive trends among the injectors. The largest spray dispersion angle and fastest velocity deceleration were observed in the 3-hole injector which showed an almost 3 times larger dispersion angle and 10% faster deceleration than the 10-hole injector. To understand possible factors governing such flow characteristics, three-dimensional internal flow simulations were conducted for the injectors. Unlike the results trend of discharged flows, the pressure and vorticity magnitude in the nozzle sac showed a linear change by altering the hole number. However, the hole-to-hole interaction of vortex flows varied in a complex way depending on the nozzle hole number. The nozzles with small and odd hole numbers, in general, showed a stronger hole-to-hole vortex interaction that can be the primary factor governing the discharged flow characteristics during the transient operation.

Combined effects of nozzle hole variation and piston bowl geometry modification on performance characteristics of a diesel engine with energy and exergy approach

This experimental work aims to address the challenges of waste management. Biomass waste is converted into useful fuel and considered as a replacement to conventional fuel in CI engines. In this context, the grape marc and grape pomace are crushed and further processed to produce grapeseed oil. The grapeseed oil is further trans esterified to produce grapeseed seed oil methyl ester. The present study aims in examining the effect of varying piston shapes and nozzle profile on energy and exergy rates of a CI engine run with grapeseed oil methyl ester (GSME) blended with cerium oxide nano particles. The CeO2 nano particles were suspended in the base fuel at a concentration of 100 ppm and stability tests were conducted. The experiments were performed on a single cylinder, water cooled diesel engine with rated power of 5.2 kW. The research work includes two additional piston shapes namely, toroidal and shallow deep and two additional nozzle profiles viz. 4 hole and 5-hole nozzle. The hemispherical shape and 3-hole nozzle were considered as the standard one. Energy and exergy analysis were done on the experimental data to understand the exergy associated with cooling water, exhaust gas and unaccounted losses. The energy and exergy rates show that increase in nozzle hole number, decreases the destructive availability of the system. The exergetic efficiency of 32.8% is higher proving that toroidal shape and 5-hole nozzle profile is comparatively better and suitable for effective engine operation. HC, CO and smoke emissions reduced considerably by 14.4%–30% by the engine modification. Brake thermal efficiency was improved from 28.2% to 31.02% for CI engine with biodiesel. The paper addresses the gap in fuel modification clubbed with engine modification using biomass waste derived fuel. Exergy and energy analysis further add value to this current experimental work.

Feasibility study of novel DME fuel injection equipment: Part 2- performance, combustion, regulated and unregulated emissions

Dimethyl Ether (DME) has emerged as a suitable alternative fuel for compression ignition (CI) engines. It is expected to be substitute fossil diesel on a large scale due to its favourable combustion characteristics and sustainable production. This study evaluates the combustion and emission characteristics of a 3-cylinder, water-cooled CI engine fuelled by DME for off-road vehicles, typically used in the agriculture sector. A detailed-chemistry based 3D CFD software is used for simulations in this study. The findings indicate that the baseline diesel fuel injection equipment (FIE), when used for DME injection, is inadequate to match the reference diesel engine performance. Therefore several modified configurations are evaluated in this study using a simulation approach. Modified fuel injection equipment (FIE) significantly reduced the emissions of NOx, soot, UHC, CO and VOC without compromising the base engine power generation. Due to the lower ignition delay of DME, the observed start of ignition advanced. It led to a lower peak firing temperature than its diesel counterpart. The lower cooling loss ratio of the DME engine established its potential as a low-heat-rejection engine. The lower calorific value of DME leads to a 50% increase in the specific fuel consumption than diesel. However, these two fuels seem to be similar on a specific energy consumption basis. A comprehensive study of the un-regulated emission species such as formaldehyde (CH2O), hydrogen peroxide (H2O2), methane (CH4), ethylene (C2H4), and acetylene (C2H2) indicate that DME combustion results in lower unregulated emissions than baseline diesel. A higher number of nozzle holes and an increased mean effective injection pressure (MEIP) of the FIE generate a conducive environment exhibiting superior engine performance and reduced emissions. However, the study identifies a few aberrations in the operating conditions, which show deteriorated emission trends, which should be avoided during the physical engine testing on DME. This study showcases the tremendous potential of an oxygenated fuel such as DME to facilitate the emergence of thermally efficient and cleaner engines, with very low regulated and unregulated emissions, indicating their future for off-highway vehicles.

Effects of antioxidant additive and injector hole number on combustion phenomenon of DI diesel engine operating with kapok methyl ester blends

AbstractAlternate fuel research is aimed at improving the eminence of combustion behavior. This result focusses on the effects of injector hole number and antioxidant additives on combustion properties of diesel engine fueled with kapok methyl ester blends. Forty percent blend of kapok methyl ester was examined with a single cylinder diesel engine. The parameters of combustion such as peak pressure, net heat release, mean gas temperature were recorded and the influence of nozzle hole number and additives on the above said properties were thoroughly analyzed. From the experimental results it is evident that 6 hole nozzle along with B40 blended with 1000 ppm of tertiary butyl hydro quinone produced highest heat release rate of 102 J/°CA. Propyl gallate exhibited its lowest BSFC of 0.269 kg/kW h with B40 blend at minimum load.

CFD-Guided Evaluation of Spark-Assisted Gasoline Compression Ignition for Cold Idle Operation

A closed-cycle, three-dimensional (3D) computational fluid dynamics (CFD) analysis campaign was conducted to evaluate the performance of using spark plugs to assist gasoline compression ignition (GCI) combustion during cold idle operations. A conventional spark plug using single-sided J-strap design was put at a location on the cylinder head to facilitate spray-guided spark assistance. Ignition was modeled with an L-type energy distribution to depict the breakdown and the arc-to-glow phases during the energy discharge process. Several key design parameters were investigated, including injector clocking, number of nozzle holes, spray inclusion angle, number of fuel injections, fuel split ratio, and fuel injection timings. The study emphasized the region around the spark gap, focusing on flame kernel formation and development and local equivalence ratio distribution. Flame kernel development and the ignition process were found to correlate strongly with the fuel stratification and the flow velocity near the spark gap. The analysis results showed that the flame kernel development followed the direction of the local flow field. In addition, the local fuel stratification notably influenced early-stage flame kernel development due to varying injection spray patterns and the fuel injection strategies. Among these design parameters, the number of nozzle holes and fuel injection timing had the most significant effects on the engine combustion performance.

Experimental Investigation of Air–Fuel Mixing Effects on Flame Characteristics in a Direct fired Burner

The length and pattern of air–fuel mixing plays a significant role in the uniformity, flame temperature, and emission characteristics, which can lead to a superior product quality in a non-oxidizing direct fired burner for a cold-rolled steel plate furnace. In this study, a diffusion-flame-type burner and partially-premixed-type burner were experimentally investigated to understand their effects on flame shape, flame temperature, and exhaust gas characteristics. With this aim, fuel nozzle size, nozzle hole number, fuel injection angle, and mixing distance of fuel and air were varied during the experiments. Computational fluid dynamics simulations were also performed to investigate the air–fuel mixing state for a nozzle-mixed burner and a partially-premixed burner. The results show that the flame temperature of the partially-premixed burner increases by up to 26 °C on average compared to that of the nozzle-mixed burner. It is also shown that the mixing distance plays an important role in the flame temperature of the partially-premixed burner. In addition, the residual oxygen concentration and volume ratio of CO/CO2 in the flue gas of the partially-premixed burner exhibit lower concentrations compared to those of the diffusion flame burner.

Improving the performance of a diesel engine by changing injectors characteristics after reduction on the compression ratio

In order to repair internal combustion engines, sometimes it is necessary to replace the components of these engines with each other. Therefore changes in engine performance are inevitable in these conditions. In the present study, by changing the coneccting rod and the crank of the OM457 turbo diesel-fueled engine with the OM444, it was observed that the performance of the engine decreases. Numerical simulations have been carried out to study the Possible ways to mitigate this reduction. One way to achieve this goal is to change the fuel injector’s characteristics such as, fuel injector’s nozzle hole diameter, number of nozzle holes, and start time of fuel injection. In this study, the impact of these parameters on the performance and emissions of these engines were analyzed. Another scenario is an increase in inlet fuel and air by the same amount. The results indicate that By reducing the diameter of fuel injector holes and hole numbers, the performance of the engine was increased. on the other hand, the NOx emissions were increased while the amount of soot emission decreased. The same results were concluded by retarding the start time of injection. Subsequently, a case study of changing fuel injector parameters for mitigation of decreased performance was performed. These parameters were simultaneously applied, and results were compared. The performance of the engine with improved injector’s characteristics was close to the main OM457. Similar results were obtained by increasing the amount of inlet air and fuel.

Optimization of performance and emission characteristics of compression ignition engine powered with Azolla pinnata fuel blends – A response surface methodology approach

ABSTRACT Biodiesels possess enhanced emission characteristics in comparison with neat diesel; therefore, biodiesel can be considered as a substitute for diesel and if blended with diesel, gives enhanced performance characteristics. In this study, tests on the performance of engine were carried out at a different number of nozzle holes (HN), the weight percentage of blends, and loads with the main focus to identify the optimal process parameter which minimizes Brake Specific Energy Consumption (BSEC), maximize Brake Thermal Efficiency (BTE), and minimize emission parameters like smoke, Carbon monoxide (CO), Hydrocarbon (HC), and Nitrogen oxides (NOx). The design of the experiment was based on the RSM Design of experiments. Using the RSM desirability function, process parameters are optimized for better performance. The influence of process parameters on responses is investigated using analysis of variance (ANOVA). Blending ratio has the maximum percentage contribution of 47.64% and 61.04% for BSEC and NOx, the load has the maximum percentage contribution of 39.69% and 65.12% for BTE and smoke, respectively, HN has a maximum percentage contribution of 80.6% and 56.41% for CO and HC, respectively. The optimal parameters of six holes in the fuel injector, 20% of biofuel with 80% of diesel, and 65% of load are identified.

Influence of the diesel pilot injector configuration on ethanol combustion and performance of a heavy-duty direct injection engine

Thanks to its properties and production pathways, ethanol represents a valuable alternative to fossil fuels, with potential benefits in terms of CO2, NOx, and soot emission reduction. The resistance to autoignition of ethanol necessitates an ignition trigger in compression-ignition engines for heavy-duty applications, which in the current study is a diesel pilot injection. The simultaneous direct injection of pure ethanol as main fuel and diesel as pilot fuel through separate injectors is experimentally investigated in a heavy-duty single cylinder engine at a low and a high load point. The influence of the nozzle hole number and size of the diesel pilot injector on ethanol combustion and engine performance is evaluated based on an injection timing sweep using three diesel injector configurations. The tested configurations have the same geometric total nozzle area for one, two and four diesel sprays. The relative amount of ethanol injected is swept between 78 – 89% and 91 – 98% on an energy basis at low and high load, respectively. The results show that mixing-controlled combustion of ethanol is achieved with all tested diesel injector configurations and that the maximum combustion efficiency and variability levels are in line with conventional diesel combustion. The one-spray diesel injector is the most robust trigger for ethanol ignition, as it allows to limit combustion variability and to achieve higher combustion efficiencies compared to the other diesel injector configurations. However, the two- and four-spray diesel injectors lead to higher indicated efficiency levels. The observed difference in the ethanol ignition dynamics is evaluated and compared to conventional diesel combustion. The study broadens the knowledge on ethanol mixing-controlled combustion in heavy-duty engines at various operating conditions, providing the insight necessary for the optimization of the ethanol-diesel dual-injection system.

Effect of Nozzle Hole Number on Diesel Engine Using Diesel and Biodiesel Blends

In this work the experiment was carried out to investigate the performance, combustion and emissions by changing the number of nozzle holes of the injector such as 3 hole, 4 hole and 5 hole by maintaining the hole diameter as 0.25mm. The experiments are executed on Kirloskar 4-stroke computerized single cylinder air cooled and electrical dynamometer coupled DI diesel engine with diesel, Rubber seed methyl ester and B20 Blend as fuels at 1500 rpm, with the injection timing of 23.4°BTDC with an injection pressure of 240 bar maintained constant throughout the experiment. It is found that 4 hole nozzle gives higher brake thermal efficiency, lower specific fuel consumption, CO, HC, for Diesel, Biodiesel and B20 Blend compared with other two nozzle holes. However the NOX got increased which is more for all the tested fuels by varying a number of nozzle hole diameter.

Numerical analysis of fuel injection configuration on nitrogen oxides formation in a jet engine combustion chamber

Emissions of nitrogen oxides from the aviation sector, contrary to the land-based sources, have doubled compared to 1990. Aircraft unique location in the upper atmosphere and daily growth of air-based traffic require particular attention to the effects of these emissions. One way to cope with this problem is to develop and design more efficient combustion systems. In this research, the numerical modelling of combustion process inside a jet engine combustion chamber is presented. The investigated chamber is a theoretical can type chamber mounted with a double stage radial swirler. The advanced k-zeta-f turbulence model was utilised to model the turbulent behaviour, while the spray process was described by the Euler Lagrangian spray modelling approach. Two different modelling approaches for describing the combustion process were employed: reduced chemical mechanism and the 3-zone extended coherent flame (ECFM-3Z) combustion model. Considering the analysis of relevant physical quantities and taking into account the reduction of computational costs while using the ECFM-3Z combustion model, it was employed for analysis of the influence of spray and emission processes by varying number and positioning of fuel introduction nozzle holes. Increase in the number of nozzle holes and their correct positioning can result in emission reduction up to 60%. Such behaviour could be addressed to the specific spray cloud formation and smaller high-temperature regions. Results showed that the presented model can be used as a modern design tool in the early stage of the combustion chamber development.

Effect of nozzle hole geometry on the operation of kapok biodiesel in a diesel engine

The strive for mitigation of toxic pollutant emissions and carbon footprints has resulted in the incursion of many renewable alternate fuels, produced from bio-derived sources. Amongst them, biodiesel, an ester of vegetable oil, has amassed immense popularity and interest for diesel engine applications. In order to operate higher blends of biodiesel in a diesel engine, engine design modification strategies are essential. This study investigates the effect of nozzle hole geometry on the characteristics of a diesel engine fueled by biodiesel. Based on this modification, the number of nozzle holes was increased from three to five and the engine characteristics were examined for the higher blend B50 (50% kapok biodiesel + 50% diesel). Modifying the nozzle hole geometry resulted in improved combustion characteristics on account of expected enhanced fuel atomization and air/fuel mixing process. The experimental study revealed an increase in peak heat release rate and in-cylinder pressure of 32.5% and 10%, respectively, for B50 when the number of nozzle holes was increased from 3 to 5 at full load condition. Furthermore, the ignition delay was shortened with a shorter burn duration (improved combustion rate) as the number of nozzle holes is increased. The modification of nozzle hole geometry offers the benefit of improved engine performance with the increase in brake thermal efficiency of 6.1% for 5 hole nozzle geometry when compared to 3 hole nozzle geometry at full load condition. Finally, from the emissions front, HC, CO, and smoke decreased with the increase in the number of nozzle holes at the penalty of increased NOX emission.

Numerical study of purging of a gasoline direct injection nozzle at the end of injection

In gasoline direct injection engines, fuel injector nozzle is one of the vital components that determine the efficiency of fuel atomization which controls combustion and emission. There is an increased focus on developing better nozzles by studying the internal flow behavior especially during the needle transient phase and at the end of injection phase. Multiphase flow characteristics involving cavitation and hydraulic flip are observed inside the nozzle during its operation. At the end of injection, fuel inside the nozzle sac and nozzle holes is purged with the gas from the engine cylinder. The efficiency of this purging process is critical to prevent the carbon deposit formation on the wall of nozzle holes and on the surface of the nozzle tip. In this article, a numerical method is presented to predict the internal nozzle flow during the needle movement and during the end of injection to predict the purging capacity of a gasoline direct injection nozzle. Needle motion is accomplished using a moving mesh method via a user-defined function. The numerical model is compared with the X-ray measurements from the literature. Based on the validated model, the study is extended to analyze various parameters like injection pressure, nozzle hole location, number of nozzle holes and the inlet rounding of the nozzle hole which affects the effectiveness of nozzle purging. Fuel wetting at the nozzle tip after the end of injection is also numerically modeled to evaluate the thickness profile of the thin liquid film.

Numerical optimization of a diesel combustion system to reduce soot mass and particle number density

In view of the recent emission legislations imposing a limit on the soot particle number density, a numerical optimization has been presented for a constant speed heavy-duty diesel engine to reduce soot particle number density while ensuring no penalty on NOx emissions. Closed cycle combustion simulations have been performed at three loads with the sectional soot model coupled to gas phase kinetics. The combustion model has been tuned at each load to ensure a good agreement for in-cylinder pressure, heat release rate and exhaust emissions. The validated combustion model has been used to study the effect of various parameters like intake swirl, start of injection, number of nozzle holes, spray angle and piston bowl shapes. Combustion simulations have been performed for every case of a full factorial design of experiments with 486 cases. Change in plume dynamics due to each parameter has been discussed in detail with the help of in-cylinder soot contours. A reentrant bowl with a higher swirl, lower number of nozzle holes and a deeper spray angle has been found to be the most promising option as it reduces the exhaust soot mass, number density with no penalty on NOx and specific fuel consumption.

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TJPRC

Effects of direct water injection and injector configurations on performance and emission characteristics of a gasoline direct injection engine: A computational fluid dynamics analysis

In-cylinder water injection is a promising approach for reducing NOx and soot emissions from internal combustion engines. It allows one to use a higher compression ratio by reducing engine knock; hence, higher fuel economy and power output can be achieved. However, water injection can also affect engine combustion and emission characteristics if water injection and injector parameters are not properly set. Majority of the previous studies on the water injection are done through experiments. Therefore, subtle aspects of water injection such as in-cylinder interaction of water sprays, spatial distribution of water vapor, and effect on flame propagation are not clearly understood and rarely reported in literature due to experimental limitations. Thus, in the present article, a computational fluid dynamics investigation is carried out to analyze the effects of direct water injection under various injector configurations on water evaporation, combustion, performance, and emission characteristics of a gasoline direct injection engine. The emphasis is given to analyze in-cylinder water spray interactions, flame propagation, water spray droplet size distribution, and water vapor spatial distribution inside the engine cylinder. For the study, the water-to-fuel ratio is varied from 0 to 1. Various water injector configurations using nozzle hole diameters of 0.14, 0.179, and 0.205 mm, along with nozzle holes of 4, 5, 6, and 7, are considered for comparison in addition to the case of no_water. Computational fluid dynamics models used in this study are validated with the available data in literature. From the results, it is found that the emission and performance characteristics of the engine are highly dependent on water evaporation characteristics. Also, the water-to-fuel ratio of 0.6 with 6 number of nozzle holes and the nozzle diameter of 0.14 mm results in the highest indicated mean effective pressure and the lowest NOx, soot, and CO emissions compared to other cases considered.

Optimization of nozzle hole number for a diesel engine fueled with kapok methyl ester blend

ABSTRACT It is evident from the past investigations that the biodiesel improves the quality of combustion and elevates the thermal efficiency. But the inevitable fact that enhanced combustion quality enhances NOx emissions. This works aims at decreasing NOx emissions by changing the injector hole number (IHN) so that the wall impingement may be reduced which would reduce the NOx emissions. The experiments are conducted for three different nozzle configurations (four holes, five holes, and six holes) for three different kapok methyl ester blends (20%, 30%, and 40%) for three loads. The Performance and emission parameters are optimized using a 3*3*3 matrix (load, biofuel blend, and IHN). As expected results indicate reduction of NOx with increase in IHN. CO, HC, and smoke also see a mild decrement with increase in IHN. Brake-specific fuel consumption (BSFC) decreases with increase in IHN whereas slight increase of BSFC is observed with increase of fuel blend.