Varying Injection Pressure Research Articles

Effect of back pressure on nozzle inner flow in fuel injector

The internal nozzle flow has great influence on fuel injection and spray. This work investigates the impacts of the injection back pressure on the nozzle inner cavitation developing, especially the flow characteristic during choking process. Based on the theoretical analysis, a three-dimension numerical model is developed to investigate the details of the inner nozzle cavitation flow. The numerical model is verified by experiments on a diesel fuel system test rig under different boundary pressures, including varied injection pressure and back pressure. The investigation shows that for a given injection pressure, cavitation occurs with the drop in the back pressure. The incipient bubbles appear just at the upper corner of nozzle inlet hole, and the cavitation area continues to expand until it reaches to the nozzle outlet. The nozzle inner cavitation is divided into three periods: no cavitation period; local cavitation developing period and super cavitation period. Before the super cavitation, as the back pressure drops, bubbles at the entrance of the nozzle hole cover more area, but the average liquid velocity increases and as a result the mass flow increases. Once the liquid velocity reaches to its maximum, the cavitation of the nozzle inlet hole maintains stable, so does the vapor–liquid mixture cross section, and the effective cross section of the liquid phase is minimum; by now the super cavitation forms. Under the condition of the super cavitation, the nozzle inner flow becomes choking and the back pressure has little influence on the mass flow, but the discharge coefficient declines as the back pressure decreases. During the choking flow period, when the back pressure declines, along the nozzle hole central axis from the inlet to the outlet, the effective flow cross section maintains stable in sequence and the liquid velocity also reaches its maximum in order. Moreover, at the outlet of the nozzle hole, super cavitation induces the increase of the turbulence kinetic energy and the outlet velocity. This increased outlet velocity makes up for the loss of the contracting effective flow passage due to super cavitation, thus the total mass flow maintains the same value after choke even the back pressure decreases.

Exhaust Gas Emission Analysis for Variable Injection Pressure 1-Cylender Engine for 2 Different Feedstock Biodiesel Blended in Diesel

Exhaust Gas Emission Analysis for Variable Injection Pressure 1-Cylender Engine for 2 Different Feedstock Biodiesel Blended in Diesel

Spray characteristics of diesel and derivatives in direct injection diesel engines with varying injection pressures

The combustion and emission characteristics of inedible oils and their derivatives are quite different from those of mineral diesel; in particular, inedible oils and their derivatives present higher molecular, relative density, and vaporization characteristics. These properties exert great impacts on the fuel spray as well as the interactions of this spray with air in the combustion chamber. Thus, examining spray characteristics, including spray cone angle, spray tip penetration, spray area, and fuel atomization, is necessary. The spray characteristics of fuel mainly depend on the fuel injection pressure, density, viscosity, ambient pressure, and temperature. Among these parameters, fuel injection pressure significantly affects the spray structure. In this study, experiments were conducted using diesel, jatropha oil methyl ester, karanja oil methyl ester, and two biodiesel blended fuels (JB20 and KB20)] as fuels in a diesel engine with different injection pressures. Optical techniques for spray visualization and image processing are very efficient tools for analyzing the spray parameters of the tested fuels. Macroscopic spray properties, such as spray tip penetration, spray cone angle, and spray area, were acquired from images captured by a high-speed video camera. The Sauter mean diameter and spray volume of all of the tested fuels were also estimated. Experimental results showed that the biodiesel blends demonstrate features different from those of diesel fuel. KB100 presented the highest spray tip penetration and spray area, followed by JB100 JB20, KB20 and diesel. Diesel fuel showed the best spray parameters, followed by JB20, KB20, KB100 and JB100. The tested fuels exhibited better spray characteristics at higher injection pressures than at lower ones.

Injection characteristics of gaseous jet injected by a single-hole nozzle direct injector

Engine manufacturers have focused on natural gas spark ignition engines due to the strict regulations for the reduction of emission levels. However, the characteristics of injectors play an important role in mixture formation and combustion. Two methods to identify the injection characteristics of the gaseous fuel injector which is applied in Spark Ignition Direct Injection (SIDI) engine are described. The first method studies the structure of Compressed Natural Gas (CNG) jet which is directly injected into an optical constant volume chamber for different pressure ratios. Schlieren photography is used to visualize the jet development. The correlation of tip penetration for near and far field of the jet is presented. The second experiment investigates the variations of mass flow rate due to variation of injection pressure and pressure of chamber. The results of this method indicate that mass flow rate through the injector is affected by the injection pressure linearly while it is not influenced by the pressure of chamber.

English

In the present study an experimental work had been carried out to analyze the combustion parameters of B20 neem blend by varying injection pressure and nozzle hole diameter. The engine tests are conducted on kirloskar 4- stroke single cylinder 1500 rpm water cooled direct injection diesel engine with eddy current dynamometer with standard injection timing 23˚bTDC was maintained constant throughout the experiment. 3 different injection pressures such as 210 bar, 230 bar, 250 bar and 3 different nozzles such as (3×0.28mm), (4×0.23mm), (5×0.20mm) varied to analyze the combustion parameters. From the test results, it could be observed that among 3 different nozzles (3×0.28mm) nozzle gives higher Peak pressure rise as compared to 4 hole nozzle and 5 hole nozzle.

Assessment of soot particle-size imaging with LII at Diesel engine conditions

Two-time-step laser-induced incandescence (LII) imaging was performed in Diesel engine-relevant combustion to investigate its applicability for spatially resolved measurements of soot primary particle sizes. The method is based on evaluating gated LII signals acquired with two cameras consecutively after the laser pulse and using LII modeling to deduce the particle size from the ratio of local signals. Based on a theoretical analysis, optimized detection times and durations were chosen to minimize measurement uncertainties. Experiments were conducted in a high-temperature high-pressure constant-volume pre-combustion vessel under the Engine Combustion Network’s “Spray A” conditions at 61–68 bar with additional parametric variations in injection pressure, gas temperature, and composition. The LII measurements were supported by pyrometric imaging measurements of particle heat-up temperatures. The results were compared to particle-size and size-dispersion measurements from transmission electron microscopy of soot thermophoretically sampled at multiple axial distances from the injector. The discrepancies between the two measurement techniques are discussed to analyze uncertainties and related error sources of the two diagnostics. It is found that in such environment where particles are small and pressure is high, LII signal decay times are such that LII with standard nanosecond laser and detector equipment suffers from a strong bias toward large particles.

Relationship between LPG fuel and gasoline injection duration for gasoline direct injection engines

Abstract LPG, liquified petroleum gas, is one of the most popular alternative fuels for internal combustion engines. Currently, it is quite easy to adapt a gasoline Multipoint Injection (MPI) engine’s fuel system to LPG supply. There are several types of systems that adapt the engine in this way, and many manufacturers, which provide different structural solutions. Usually the LPG control unit is based on signals from the original gasoline supply system. This method is more complicated for direct injection engines, where the fuel dose depends not only on the injection duration but also on variations in injection pressure. In this study the relationship between LPG fuel and gasoline injection duration for gasoline direct injection engines was investigated. This relationship took gasoline injection pressure as a variable. The analysis was based on simple equations of incompressible and compressible steady flow. It was improved by an experiment which allowed the evaluation of injectors’ flow characteristics. The results were also compared with the data provided by the manufacturer of LPG systems for MPI engines.

Performance and emission characteristics of a diesel engine with varying injection pressure and fuelled with raw mahua oil (preheated and blends) and mahua oil methyl ester

The present experimental investigation aims to depict the effect of varying injection opening pressure (IOP) using diesel-mahua oil (raw) blends as fuel on the characteristics of a small agricultural engine. The effect of preheated mahua oil and mahua oil methyl ester (MOME) as fuel on engine characteristics has also been investigated. Series of short-term tests were conducted on a single cylinder, 3.7 kW, water cooled, stationary diesel engine and performance and emission characteristics were determined using different diesel-mahua oil blends and also with varying IOP. Optimal IOP as well as blend ratio was determined for maximum efficiency and minimum emission values. Further, a novel pipe in pipe counter flow heat exchanger was designed and fabricated to arrange for preheating the raw mahua oil with exhaust gases of the engine. MOME was also prepared and tested as fuel in engine. Characterisation for major properties of all test fuels was conducted. Performance and emission characteristics of the diesel engine for raw mahua oil blends (unheated) at both rated and optimal IOP were compared with those of diesel, MOME and preheated raw mahua oil. At IOP of 226 bar, maximum brake thermal efficiency was obtained for M10, M20 and M30 blends. Significant reduction in carbon monoxide and hydrocarbon emission were observed. Nitrogen oxides emissions increased marginally. It was also observed that preheated mahua oil as fuel increases efficiency and reduces emissions. The use of M10 even at rated injection pressure and M20 and M30 at 226 bar results in minimum loss of efficiency and generates higher environmental benefits.

Macroscopic spray characterization under high ambient density conditions

The combustion process in the diesel engine is significantly affected by the fuel spray characteristics and fuel–air mixing process. Therefore, spray development process plays a vital role in combustion and emission formations which makes the study on spray characteristics: an essential entity to better understand the combustion process in detail. Thus this study is focused on non-evaporative spray characterization in a constant volume chamber, specially built to simulate the engine combustion chamber condition during injection process. Then the experimental results were compared with numerical results obtained from internal nozzle flow and spray simulations and found better agreement with each other. The results were obtained in terms of momentum flux, spray tip penetration, spray angle and spray volume. From the results, it can be inferred that the momentum flux, spray tip penetration and fuel air mixing increases with increasing injection pressure or decreasing ambient density. However, momentum coefficient and spray angle remains unchanged with injection pressure variations. The liquid length increases and sauter mean diameter decreases with increasing pressure difference at higher temperature ensuring better atomization of fuel.

Experimental Study on Diesel Engine and Analysis the Spray Characteristics of Diesel and Biodiesel by Varying Injection Pressure

— The spray characteristic of the injected fuel is mainly depends upon fuel injection pressure, temperature, ambient pressure, fuel viscosity and fuel density. An experimental study was conducted to examine the effect of injection pressure on the spray was injected into direct injection (DI) diesel engine in the atmospheric condition. In Diesel engine, the window of 20 mm diameter hole and the transparent quartz glass materials were used for visualizing spray characteristics of combustion chamber at right angle triangle position. The varying Injection pressure of 180 - 240 bar and the engine was hand cranked for conducting the experiments. Spray characteristics for Jatropha oil methyl ester (JOME) and diesel were studied experimentally. Spray tip penetration and spray cone angle were measured in a combustion chamber of Direct Injection diesel engine by employing high speed Digital camera using Mie Scattering Technique and ImageJ software. The study shows the JOME gives longer spray tip penetration and smaller spray cone angle than those of diesel fuels. The Spray breakup region (Reynolds number, Weber number), Injection velocity and Sauter Mean Diameter (SMD) were determined for diesel and JOME. SMD decreases for JOME than diesel and the Injection velocity, Reynolds Number, Weber Number Increases for JOME than diesel.

Influence of Fuel Injection Timing and Pressure on In-Flame Soot Particles in an Automotive-Size Diesel Engine

The current understanding of soot particle morphology in diesel engines and their dependency on the fuel injection timing and pressure is limited to those sampled from the exhaust. In this study, a thermophoretic sampling and subsequent transmission electron microscope imaging were applied to the in-flame soot particles inside the cylinder of a working diesel engine for various fuel injection timings and pressures. The results show that the number count of soot particles per image decreases by more than 80% when the injection timing is retarded from -12 to -2 crank angle degrees after the top dead center. The late injection also results in over 90% reduction of the projection area of soot particles on the TEM image and the size of soot aggregates also become smaller. The primary particle size, however, is found to be insensitive to the variations in fuel injection timing. For injection pressure variations, both the size of primary particles and soot aggregates are found to decrease with increasing injection pressure, demonstrating the benefits of high injection velocity and momentum. Detailed analysis shows that the number count of soot particles per image increases with increasing injection pressure up to 130 MPa, primarily due to the increased small particle aggregates that are less than 40 nm in the radius of gyration. The fractal dimension shows an overall decrease with the increasing injection pressure. However, there is a case that the fractal dimension shows an unexpected increase between 100 and 130 MPa injection pressure. It is because the small aggregates with more compact and agglomerated structures outnumber the large aggregates with more stretched chain-like structures.

Performance, Emissions and Combustion Characteristics of Waste Fried Vegetable Oil in Based Biodiesel in High Grade Low Heat Rejection Diesel Engine

Experiments were conducted to evaluate the performance of a high grade low heat rejection (LHR) diesel engine with air gap insulated piston, air gap insulated liner and ceramic coated cylinder head (ceramic coating of thickness 500 microns was done on inside portion of cylinder head) with different operating conditions (normal temperature and pre-heated temperature) of waste fried vegetable oil based diesel (WFVOBD) with varied injection pressure and injection timing and compared the performance with one over the other and also with pure diesel operation on conventional engine (CE). Performance parameters of brake thermal efficiency, exhaust gas temperature and volumetric efficiency were determined at various values of brake mean effective pressure (BMEP). Exhaust emissions of smoke and oxides of nitrogen (NOx) were recorded at different values of BMEP. Combustion characteristics at peak load operation of the engine were measured with TDC (top dead centre) encoder, pressure transducer, console and special pressure-crank angle software package. CE showed compatible performance, while LHR engine showed improved performance with waste fried vegetable oil in biodiesel form at recommended injection timing and pressure and the performance of both version of the engine improved with advanced injection timing and at higher injection pressure when compared with CE with pure diesel operation. The optimum injection timing was 33 o bTDC for CE while it is 32 o bTDC with LHR engine with biodiesel operation. Relatively, peak brake thermal efficiency increased by 18%, at peak load operation-brake specific energy consumption decreased by 6%, exhaust gas temperature decreased by 75 o C , volumetric effi- ciency decreased by 5%, coolant load decreased by 30%, sound intensity decreased by 35%, smoke levels decreased by 27% and NOx levels increased by 41% with biodiesel operation on LHR engine at its optimum injection timing, when compared with pure diesel operation on CE at manufacturer's recommended injection timing.

Demonstration of Straight Nozzle Configuration Micro Thruster for Small Satellites

This paper provides the details on assembly and process involved in realization of Straight Nozzle Configuration Micro (SNCM) Thruster. SNCM Thruster finds suitable application with low level of thrust in the range of 0.5 - 1.0N for initial attitude acquisition, attitude control and station keeping of spacecraft. Catalyst bed heater is provided on chamber to heat to around 100°C, by which Catalytic decomposition of propellant produces hot exhaust gases . These exhaust gasses are passed through convergent divergent nozzle to produce the desired thrust. High Altitude Firing Test was carried by simulating space environment on SNCM thruster with varying injection pressures. SNCM Thruster is capable to delivered thrust range from 0.5 to1.0N for the given injection pressure 1.0 to 2.4MPa respectively. The specific impulse of the SCNM thruster with hydrazine is propellant is around 200 seconds.

Urea-SCR시스템 액막형 선회분사기의 분사압력변화에 따른 무특성에 관한 연구

Abstract: In this study, the spray characteristics of a pressure swirl atomizer classified into a liquid sheet-type swirl nozzle for Urea-SCR system were investigated experimentally with the variation of injection pressure. The length to diameter ratio (l o /d) of the nozzle was 3.1, and the swirler was set inside the nozzle tip to give injecting fluid angular momentum. The injection duration of the nozzle was controlled by PWM (pulse width modulation) modes. The development processes of the spray were imaged by a 2-D PIV system, and the change of spray angle was measured. The atomization characteristics, including axial velocity and SMD, were measured using a 2-D PDA system with the injection pressures at room temperature and ambient pres-sure conditions. As the experimental results, the injection pressure had a significant impact on the spray struc-ture showing a different shape around the spray leading edge, and the smaller SMD was observed with in-creasing injection pressures, which was similar to that of the previous work.

Improving of Emissions and Performance of Rice Brawn Oil in Medium Grade Low Heat Rejection Diesel Engine

Investigations were carried out to evaluate the performance of a medium grade low heat rejection (LHR) diesel engine with air gap insulated piston and air gap insulated liner with 3-mm air gap at different operating conditions [normal temperature and pre-heated temperature] of crude rice brawn oil (CRBO) with varied injection pressure and injection timing. Performance parameters of brake thermal efficiency, exhaust gas temperature, volumetric efficiency, coolant load and sound intensity were determined at various values of brake mean effective pressure (BMEP). Exhaust emissions of smoke and oxides of nitrogen (NOx) were recorded at various values of BMEP. Combustion characteristics at peak load operation of the engine were measured with TDC (top dead centre) encoder, pressure transducer, console and special pressure-crank angle software package. Conventional engine (CE) showed deteriorated performance, while LHR engine showed improved performance with CRBO operation at recommended injection timing and pressure and the performance of both version of the engine improved with advanced injection timing and at higher injection pressure when compared with CE with pure diesel operation. The optimum injection timing was 32 o bTDC for CE while it was 30 o bTDC with LHR engine with CRBO operation. Compatible performance in terms of peak brake thermal efficiency, exhaust gas temperature, coolant load, smoke levels were observed with LHR engine with CRBO operation at recommended injection timing of 27 o bTDC. (Before top dead centre) in comparison with pure diesel operation

Comparative Performance of Crude Pongamia Oil in A Low Heat Rejection Diesel Engine

Aim: Experiments were carried out to evaluate the performance of a low heat rejection (LHR) diesel engine with ceramic coated cylinder head (ceramic coating of thickness 500 microns was done on inside portion of cylinder head) with different operating conditions (normal temperature and pre-heated temperature) of crude Pongamia oil with varied injection pressure and injection timing. Study Design: Performance parameters of brake thermal efficiency, exhaust gas temperature and volumetric efficiency were determined at various values of brake mean effective pressure (BMEP). Methodology: Exhaust emissions of smoke and oxides of nitrogen (NOx) were noted at the various values of BMEP. Combustion characteristics at peak load operation of the engine were measured with TDC (top dead centre) encoder, pressure transducer, console and special pressure-crank angle software package. Brief Results: Conventional engine (CE) showed deteriorated performance, while LHR engine showed improved performance with biodiesel operation at manufacturer's recommended injection timing of 27 o bTDC and pressure of 190 bar. The performance of both version of the engine was improved with advanced injection timing and at higher injection pressure when compared with CE with pure diesel operation. The optimum injection timing was 32 o bTDC for CE, while it was 29 o bTDC for LHR engine with CPO operation. Peak brake thermal efficiency increased by 7%, smoke levels timing, when compared with pure diesel operation on

The study on increase low permeability reservoir adsorption ability with nano-polymerisation emulsion

Low permeability reservoirs always have some problems such as long-termed high injection pressure, low injection rate, the great variation of injection pressure during the water injection because of the compact and complicated structure. So it is necessary to reduce injection pressure and augment injection rate. Water-based nanometre polysilicon break through the limitation of organic scattered carry agent by decentralising in water phase as micro-emulsion status, which is becoming a prospected stimulation of water injection technology. This micro-emulsion has many advantages, such as strong interfacial activity and changing the rock wettability, easily absorption on the rock surface. So it can decrease flow resistance by displacement the water film adsorbing on surface of the water wet rock. The experiment results show that the water absorption ability of natural core matrix improves and injection pressure reduces 50% after 1.0 PV 3,500 mg/L nano-polymerisation emulsion treatment. Simultaneously, the roles of adsorption, wettability reverse, interfacial activity and stripping are played markedly by coordinated using the technology and acidising technique in low-permeability reservoirs development.

A study of safe CO2storage capacity in saline aquifers: a numerical study

An effective way of reducing greenhouse gas content in the atmosphere is carbon dioxide (CO2) geo-sequestration in saline aquifers. The main objective of this study is to develop a 3-D numerical model to identify the optimum CO2 storage capacity in saline aquifers by studying the factors affecting it and the possibility of the injected CO2 back-migrating into the atmosphere. A 1000m×1000m×184 m saline aquifer, lying 800 m below the ground surface, was therefore considered to develop a model using the COMET 3 reservoir simulator. The effects of injecting CO2 properties (injection pressure) and the aquifer's properties (depth, temperatures and salinity) on the CO2 storage capacity were examined first. According to the results of the model, CO2 storage capacity increases with increasing injection pressure and salinity and decreasing depth and temperature, and 100% variations in injection pressure, depth, temperature and salinity levels cause the CO2 storage capacity to be changed by 54%, 36%, 18% and 1.8%, respectively. The next stage of the study involved the determination of cap rock failure due to CO2 injection pressure and the identification of the factors influencing it. A detailed parametric study was conducted, with changes to the depth, temperature and salinity with respect to injection pressure, to detect the effects of these factors on the optimum CO2 injection pressure. According to the results, optimum CO2 injection pressure clearly depends on the aquifer depth and the effects of salinity and temperature are negligible. An increment of 0.8 to 1.4 km in aquifer depth causes the optimum injection pressure to be increased from 19.55 to 42 MPa, which is about 105 and 107 higher than the effects of temperature (20 to 110 °C increment) and salinity level (100,000 to 160,000 ppm increment), respectively. The model can be used effectively in field studies to safely enhance CO2 storage capacity in saline aquifers. Copyright © 2012 John Wiley & Sons, Ltd.

An Analysis of Reservoir Production Strategies in Miscible and Immiscible Gas Injection Projects

Successful design and implementation of a miscible gas injection project depends upon the minimum miscibility pressure (MMP) and other factors such as reservoir and fluid characterization. The experimental methods available for determining MMP are both costly and time consuming. Therefore, the use of correlations that prove to be reliable for a wide range of fluid types would likely be considered acceptable for preliminary screening studies. This work includes a comparative evaluation of MMP correlations and thermodynamic models using an equation of state by PVTsim software (Schlumberger, 2001a). We observed that none of the evaluated MMP correlations studied in this investigation is sufficiently reliable. EOSbased analytical methods seemed to be more conservative in predicting MMP values. Following an acceptable estimate of MMP, several compositional simulation runs were conducted to determine the sensitivity of the oil recovery to variations in injection pressure (at pressures above, equal to and below the estimated MMP), stratification and mobility ratio parameters in miscible and immiscible gas injection projects. Simulation results indicated that injection pressure was a key parameter that affects oil recovery to a high degree. MMP determined to be the optimum injection pressure. Stratification and mobility ratio could also affect the recovery efficiency of the reservoir in a variety of ways. Key words : Reservoir production; Miscible gas injection; Immiscible gas; Minimum miscibility pressure

Performance Evaluation of a Low-Grade Low-Heat-Rejection Diesel Engine with Crude Pongamia oil

Investigations are carried out to evaluate the performance of a low heat rejection (LHR) diesel engine with ceramic coated cylinder head [ceramic coating of thickness 500 microns is done on inside portion of cylinder head] with different operating conditions [normal temperature and pre-heated temperature] of crude Pongamia oil (CPO) with varied injection pressure and injection timing. Performance parameters and pollution levels are determined at various magnitudes of brake mean effective pressure. Combustion characteristics at peak load operation of the engine are measured with special pressure-crank angle software package. Conventional engine (CE) showed deteriorated performance, while LHR engine showed improved performance with CPO operation at recommended injection timing and pressure and the performance of both version of the engine is improved with advanced injection timing and at higher injection pressure when compared with CE with pure diesel operation. The optimum injection timing is 31°bTDC for conventional engine while it is 29°bTDC with LHR engine with vegetable oil operation. Peak brake thermal efficiency increased by 5%, smoke levels decreased by 2% and NOx levels increased by 40% with CPO operation on LHR engine at its optimum injection timing, when compared with pure diesel operation on CE at manufacturer’s recommended injection timing.