scholarly journals Application of CFD, Taguchi Method, and ANOVA Technique to Optimize Combustion and Emissions in a Light Duty Diesel Engine

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
Senlin Xiao ◽  
Wanchen Sun ◽  
Jiakun Du ◽  
Guoliang Li
Keyword(s):  
Diesel Engine ◽  
Taguchi Method ◽  
Fuel Consumption ◽  
Soot Formation ◽  
Dynamics Simulation ◽  
Injection Timing ◽  
Light Duty ◽  
Study Results ◽  
Main Injection ◽  
Pilot Fuel

Some previous research results have shown that EGR (exhaust gas recirculation) rate, pilot fuel quantity, and main injection timing closely associated with engine emissions and fuel consumption. In order to understand the combined effect of EGR rate, pilot fuel quantity, and main injection timing on theNOx(oxides of nitrogen), soot, and ISFC (indicated specific fuel consumption), in this study, CFD (computational fluid dynamics) simulation together with the Taguchi method and the ANOVA (analysis of variance) technique was applied as an effective research tool. At first, simulation model on combustion and emissions of a light duty diesel engine at original baseline condition was developed and the model was validated by test. At last, a confirmation experiment with the best combination of factors and levels was implemented. The study results indicated that EGR is the most influencing factor onNOx. In case of soot emission and ISFC, the greatest influence parameter is main injection timing. For all objectives, pilot fuel quantity is an insignificant factor. Furthermore, the engine with optimized combination reduces by at least 70% forNOx, 20% in soot formation, and 1% for ISFC, in contrast to original baseline engine.

A Computational Study on the Effects of Pre-Ignition Processes on Diesel Engine Combustion and Emissions

2011 ◽  
Author(s):  
S. K. Aggarwal ◽  
D. E. Longman
Keyword(s):  
Diesel Engine ◽  
Fuel Consumption ◽  
Soot Formation ◽  
Premixed Combustion ◽  
Injection Timing ◽  
Emission Characteristics ◽  
Moderate Increase ◽  
Gas Temperature ◽  
Piston Bowl ◽  
Engine Combustion

There has been significant progress in reducing NOx and particulate emissions from diesel engines. However, many challenges remain particularly in view of the global energy issues and increasingly stringent emission regulations. Several recent efforts have focused on achieving low-temperature, premixed combustion for simultaneously reducing NOx and PM emissions, but without any detrimental effect on fuel consumption and energy density. Various strategies being explored include homogeneously charged compression ignition (HCCI), reducing flame temperature through excessive EGR, enhancing premixed combustion by controlling injection parameters, and promoting premixing by using early injection and low cetane number fuels. The present study is aimed at examining the effects of injection timing, initial gas temperature, and cylinder and piston wall temperatures on the spray processes, and thereby on the ignition, combustion and emission characteristics in a diesel engine. The reacting two-phase flow field in a 1.9L, 4-cylinder GM diesel engine is simulated using a CFD code ‘CONVERGE’, which employs an innovative cut-cell Cartesian method for grid generation, and a semi-detailed reaction mechanism for n-heptane combustion. A 51.430 sector with a single hole is considered to simulate the 7-hole common-rail injector. Results indicate that while the initial gas temperature does not affect the spray and combustion behavior qualitatively, it modifies combustion temperatures and thus NOx emissions noticeably. On the other hand, the piston and cylinder wall temperatures qualitatively influence the spray behavior and thereby the combustion and emission behavior. The injection timing has a strong influence on the spray and mixture formation processes, and thus on the combustion and emission characteristics. Delaying the start of injection (SOI) can lead to a significant reduction in NOx formation with only a moderate increase in soot formation. A detailed analysis of the spray and combustion processes indicated two main fuel consumption regions, one near the piston bowl wall and the other in the main spray near the injector. Fuel consumption in the first region mainly follows the conventional diesel combustion model involving rich premixed burning and diffusion burning, while that in the second region involves premixed combustion. As the SOI is delayed, the spray impingement on the piston bowl wall increases, causing more fuel consumption in the first region, which leads to reduction in NOx but increase in soot formation, indicating a tradeoff between NOx and soot emissions. However, with further delay in the SOI, the amount of fuel consumption in the first region increases significantly, while that in the main spray region involves lean premixed combustion. The net effect is a significant reduction in NOx with only a moderate increase in soot emission. Future studies will focus on the effects of modifying the level of premixing and the ignition delay on diesel engine combustion and emission.

Two-Stroke Marine Diesel Engine Variable Injection Timing System Performance Evaluation and Optimum Setting for Minimum Fuel Consumption at Acceptable NOx Levels

2014 ◽  
Author(s):  
Dimitrios T. Hountalas ◽  
Spiridon Raptotasios ◽  
Antonis Antonopoulos ◽  
Stavros Daniolos ◽  
Iosif Dolaptzis ◽  
...  
Keyword(s):  
Diesel Engine ◽  
Fuel Consumption ◽  
Engine Performance ◽  
Operating Conditions ◽  
Specific Fuel Consumption ◽  
Injection Timing ◽  
Nox Emissions ◽  
Pressure Measurements ◽  
Cylinder Pressure ◽  
Start Of Injection

Currently the most promising solution for marine propulsion is the two-stroke low-speed diesel engine. Start of Injection (SOI) is of significant importance for these engines due to its effect on firing pressure and specific fuel consumption. Therefore these engines are usually equipped with Variable Injection Timing (VIT) systems for variation of SOI with load. Proper operation of these systems is essential for both safe engine operation and performance since they are also used to control peak firing pressure. However, it is rather difficult to evaluate the operation of VIT system and determine the required rack settings for a specific SOI angle without using experimental techniques, which are extremely expensive and time consuming. For this reason in the present work it is examined the use of on-board monitoring and diagnosis techniques to overcome this difficulty. The application is conducted on a commercial vessel equipped with a two-stroke engine from which cylinder pressure measurements were acquired. From the processing of measurements acquired at various operating conditions it is determined the relation between VIT rack position and start of injection angle. This is used to evaluate the VIT system condition and determine the required settings to achieve the desired SOI angle. After VIT system tuning, new measurements were acquired from the processing of which results were derived for various operating parameters, i.e. brake power, specific fuel consumption, heat release rate, start of combustion etc. From the comparative evaluation of results before and after VIT adjustment it is revealed an improvement of specific fuel consumption while firing pressure remains within limits. It is thus revealed that the proposed method has the potential to overcome the disadvantages of purely experimental trial and error methods and that its use can result to fuel saving with minimum effort and time. To evaluate the corresponding effect on NOx emissions, as required by Marpol Annex-VI regulation a theoretical investigation is conducted using a multi-zone combustion model. Shop-test and NOx-file data are used to evaluate its ability to predict engine performance and NOx emissions before conducting the investigation. Moreover, the results derived from the on-board cylinder pressure measurements, after VIT system tuning, are used to evaluate the model’s ability to predict the effect of SOI variation on engine performance. Then the simulation model is applied to estimate the impact of SOI advance on NOx emissions. As revealed NOx emissions remain within limits despite the SOI variation (increase).

scholarly journals Effect of EGR Rate and Injection Timing on the Characteristics of Exhaust Emissions in Light-duty Diesel Engine

2012 ◽  
Vol 20 (3) ◽  
pp. 7-12 ◽  
Author(s):  
Ho-Jeong Gong ◽  
In-Goo Hwang ◽  
A-Hyun Ko ◽  
Cha-Lee Myung ◽  
Sim-Soo Park ◽  
...  
Keyword(s):  
Diesel Engine ◽  
Exhaust Emissions ◽  
Injection Timing ◽  
Light Duty

Parameter optimization of a diesel engine to reduce noise, fuel consumption, and exhaust emissions using response surface methodology

2005 ◽  
Vol 219 (10) ◽  
pp. 1181-1192 ◽  
Author(s):  
Z Win ◽  
R P Gakkhar ◽  
S C Jain ◽  
M Bhattacharya
Keyword(s):  
Response Surface Methodology ◽  
Diesel Engine ◽  
Response Surface ◽  
Fuel Consumption ◽  
Parameter Optimization ◽  
Direct Injection ◽  
Engine Performance ◽  
Optimization Techniques ◽  
Injection Timing ◽  
Test Engine

The conflicting effects of the operating parameters and the injection parameter (injection timing) on engine performance and environmental pollution factors is studied in this paper. As an optimization objective, a 3.5 kW small direct injection diesel engine was used as the test engine, and its speed, load, and static injection timing were varied as per 4 × 4 × 3 full factorial design array. Radiated engine noise, smoke level, brake specific fuel consumption, and emissions of unburned hydrocarbons and nitrogen oxides were captured for all test runs. Objective functions relating input and output parameters were obtained using response surface methodology (RSM). Parameter optimization was carried out to control output responses under their mean limit using multi-objective goal programming and minimax programming optimization techniques.

An Experimental Study on Smoke Reduction Effect of Post Injection in Combination With Pilot Injection for a Diesel Engine

2013 ◽  
Vol 136 (4) ◽  
Author(s):  
Long Liu ◽  
Naoto Horibe ◽  
Tatsuya Komizo ◽  
Issei Tamura ◽  
Takuji Ishiyama
Keyword(s):  
Diesel Engine ◽  
Injection Pressure ◽  
Injection Timing ◽  
Nox Emissions ◽  
Pilot Injection ◽  
Post Injection ◽  
Spray Flames ◽  
Injection Quantity ◽  
Main Injection ◽  
Reduction Effect

With the universal utilization of the common-rail injection system in automotive diesel engines, the multistage injection strategies have become typical approaches to satisfy the increasingly stringent emission regulations, and especially the post injection has received considerable attention as an effective way for reducing the smoke emissions. Normally the post injection is applied in combination with the pilot injection to restrain the NOx emissions, smoke emissions, and combustion noise simultaneously, and the pilot injection condition affects the combustion process of the main injection and might affect the smoke reduction effect of the post injection. Thus this study aims at obtaining the post injection strategy to reduce smoke emissions in a diesel engine, where post injection is employed in combination with pilot injection. The experiments were performed using a single-cylinder diesel engine under various conditions of pilot and post injection with a constant load at an IMEP of 1.01 MPa, fixed speed of 1500 rpm, and NOx emissions concentration of 150 ± 5 ppm that was maintained by adjusting the EGR ratio. The injection pressure was set at 90 MPa at first, and then it was varied to 125 MPa to evaluate the effects of post injection on the smoke reduction in the case of higher injection pressure. The experimental results show that small post injection quantity with a short interval from the end of main injection causes less smoke emissions. And larger pilot injection quantity and later pilot injection timing lead to higher smoke emissions. And then, to explore and interpret the smoke emissions tendencies with varying pilot and post injection conditions, the experimental results of three-stage injection conditions were compared to those of two reference cases, which only included the pilot and main injection, and the interaction between main spray flames and post sprays was applied for analysis. Based on the comparative analysis, the larger smoke reduction effect of post injection was observed with the larger pilot injection quantity, while it is not greatly influenced by pilot injection timing. In addition, the smoke emissions can be reduced considerably by increasing the injection pressure, however the smoke reduction effect of post injection was attenuated. And all of these tendencies were able to be interpreted by considering the intensity variation of the interaction between main spray flames and post sprays.

Effect of High Pressure Post Injection on Soot and NO Trade-Off in a DI Diesel Engine

2010 ◽  
Author(s):  
Kamran Poorghasemi ◽  
Fathollah Ommi ◽  
Vahid Esfahanian
Keyword(s):  
Diesel Engine ◽  
Soot Formation ◽  
Three Dimensional ◽  
Injection Pressure ◽  
Combustion Mechanism ◽  
Injection Timing ◽  
Post Injection ◽  
Multiple Injection ◽  
Trade Off ◽  
Di Diesel Engine

In DI Diesel engines NO and Soot trade off is an important challenge for Engineers. In this paper, at first, multiple injection strategy will be introduced as a useful way to reduce both NO and Soot emissions simultaneously. Then the effect of injection pressure in post injection on the engine emissions will be studied. Investigations have been conducted on DI diesel engine. To evaluate the benefits of multiple injection strategies and to reveal combustion mechanism, modified three dimensional CFD code KIVA-3V was used. Results showed that using post injection with appropriate dwell between injection pulses can be effective in simultaneously reduction of emissions. Based on computation results, NO reduction formation mechanism is a single injection with retarded injection timing. It is shown that reduced soot formation is because of the fact that the soot producing rich regions at the fuel spray head are not replenished by new fuel when the injection is stopped and then restarted. Also increasing injection pressure in post injection will reduce the Soot emission dramatically while NO is in control and it is due to increasing fuel burning rate in post injection pulse.

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