Comparison of Ultra-High Rail Pressures and Postinjections for Soot Reduction With Massive Exhaust Gas Recirculation

2019 ◽  
Vol 141 (9) ◽  
Author(s):  
Ryan M. Ogren ◽  
Song-Charng Kong
Keyword(s):  
Injection Pressure ◽  
Exhaust Gas Recirculation ◽  
Injection Timing ◽  
Nox Emissions ◽  
Exhaust Gas ◽  
Engine Fuel ◽  
Post Injection ◽  
High Injection ◽  
Gas Recirculation ◽  
Injection Pressures

In this study, the application of ultra-high fuel injection pressure (up to 300 MPa) is compared with that of a post injection strategy for the reduction of soot at medium load conditions with exhaust gas recirculation (EGR) rates greater than 40%. Emissions were predominantly studied at the engine's maximum brake torque speed of 1600 rpm. A 4.5-L, four-cylinder diesel engine with series turbochargers and a high-pressure EGR loop was used for all tests. Results indicate that, ultra-high injection pressures may not have large effects on hydrocarbons (HC) or CO emissions. Small soot reductions were achieved at the expense of increased NOx emissions. Post injections resulted in larger soot reductions for a small increase in NOx while allowing lower fuel pressures to be utilized. The increase in NOx emissions with a post injection was observed to be comparatively less at increased engine speeds. For operation at high EGR, post injections were observed to be more effective at reducing soot than ultra-high injection pressures. Both injection pressure and post injections were observed to have small to negligible effects on engine fuel consumption, leaving EGR and injection timing as the primary efficiency drivers at the conditions studied.

Biodiesel Combustion and Emissions in Engines Using Modern Common-Rail Fuel Injection Systems

2008 ◽  
Author(s):  
Prashanth K. Karra ◽  
Matthias K. Veltman ◽  
Song-Charng Kong
Keyword(s):  
Fuel Injection ◽  
Injection Pressure ◽  
Exhaust Gas Recirculation ◽  
Common Rail ◽  
Injection System ◽  
Injection Timing ◽  
Fuel Injection System ◽  
Nox Emissions ◽  
Exhaust Gas ◽  
Gas Recirculation

This study performed experimental testing of a multi-cylinder diesel engine using different blends of biodiesel and diesel fuel. The engine used an electronically-controlled common-rail fuel injection system to achieve a high injection pressure. The operating parameters that were investigated included the injection pressure, injection timing, and exhaust gas recirculation rate. Results showed that biodiesel generally reduced soot emissions and increased NOx emissions. The increase in NOx emissions was not due to the injection timing shift when biodiesel was used because the present fuel injection system was able to give the same fuel injection timing. At high exhaust gas recirculation rates, emissions using regular diesel and 20% biodiesel blends are very similar while 100% biodiesel produces relatively different emission levels. Therefore, the increase in NOx emissions may not be a concern when 20% biodiesel blends are used with high exhaust gas recirculation rates in order to achieve low temperature combustion conditions.

Characteristics of low temperature and low oxygen diesel combustion with ultra-high exhaust gas recirculation

2007 ◽  
Vol 8 (4) ◽  
pp. 365-378 ◽  
Author(s):  
H Ogawa ◽  
T Li ◽  
N Miyamoto
Keyword(s):  
Oxygen Concentration ◽  
Thermal Efficiency ◽  
Fuel Injection ◽  
Injection Pressure ◽  
Exhaust Gas Recirculation ◽  
Injection Timing ◽  
Exhaust Gas ◽  
Cent Oxygen ◽  
Low Oxygen ◽  
Gas Recirculation

Ultra-low NOx and smokeless operation at higher loads up to half of the rated torque is attempted with large rates of cold exhaust gas recirculation (EGR). NOx decreases below 6 ppm (0.05 g/kW h) and soot significantly increases when first decreasing the oxygen concentration to 16 per cent with cold EGR. However, after peaking at 12–14 per cent oxygen, soot then decreases sharply to essentially zero at 9–10 per cent oxygen while maintaining ultra-low NOx, regardless of fuel injection quantity and injection pressure. However, at higher loads, with the oxygen concentration below 9–10 per cent, the air-fuel ratio has to be over-rich to exceed half of the rated torque, and thermal efficiency, CO, and THC deteriorate significantly. As the EGR rate increases, exhaust gas emissions and thermal efficiency vary with the intake oxygen content rather than with the excess air ratio. Longer ignition delays due to either advancing or retarding the injection timing reduced the smoke emissions, but advancing the injection timing has the advantages of maintaining the thermal efficiency and preventing misfiring. A reduction in the compression ratio is effective to reduce the in-cylinder temperature and increase the ignition delay as well as to expand the smokeless combustion range in terms of EGR and i.m.e.p. (indicated mean effective pressure).

Effects of Nozzle Hole Arrangement on Diesel Engine Emissions

2009 ◽  
Author(s):  
Prashanth K. Karra ◽  
Song-Charng Kong
Keyword(s):  
Injection Pressure ◽  
Exhaust Gas Recirculation ◽  
Operating Conditions ◽  
Exhaust Gas ◽  
Low Temperature Combustion ◽  
Convergent Nozzle ◽  
Wide Range ◽  
Soot Emissions ◽  
Gas Recirculation ◽  
Injection Pressures

Various diesel injectors and injection pressures were tested along with exhaust gas recirculation to achieve low NOx and soot emissions. The injectors used in the study included a 6-hole nozzle, a 10-hole nozzle, and a 6-hole convergent nozzle with a K-factor of 3. All three injectors had the same flow numbers and they were effective in reducing NOx and soot emissions at appropriate conditions. It was found that low temperature combustion can be achieved by using high levels of exhaust gas recirculation with late injection timings. High injection pressures significantly reduced soot emissions at conventional injection timings. The effect of injection pressure was not significant at retarded injection timings, i.e., 5 ATDC. The convergent nozzle was found to produce higher soot emissions and its effects on NOx emissions and fuel consumption were not significant. The small nozzle size in the 10-hole injector can generate smaller fuel drops and lead to better atomization. The 10-hole injector appeared to have better air utilization and resulted in significant reductions in NOx and soot emissions over a wide range of operating conditions.

Combustion of Hydrotreated Vegetable Oil in a Diesel Engine: Sensitivity to Split Injection Strategy and Exhaust Gas Recirculation

2020 ◽  
Author(s):  
Maciej Mikulski ◽  
Jacek Hunicz ◽  
Aneesh Vasudev ◽  
Arkadiusz Rybak ◽  
Michał Gęca
Keyword(s):  
Vegetable Oil ◽  
Diesel Fuel ◽  
Fuel Injection ◽  
Exhaust Gas Recirculation ◽  
Injection Timing ◽  
Nox Emissions ◽  
Exhaust Gas ◽  
Injection Strategy ◽  
Soot Emissions ◽  
Gas Recirculation

Abstract This work explores the potential to optimize advanced common-rail engines for operation with hydrotreated vegetable oil (HVO). The single-cylinder engine research focuses on adjusting the injection strategy and external exhaust gas recirculation (EGR) to achieve the optimum performance-emissions trade-off using HVO. The engine is operated at a fixed rotational speed of 2000 rpm and under constant load (net indicated mean effective pressure of 0.45 MPa). Split fuel-injection strategy is used: main injection timing is fixed but pilot injection is varied both in terms of timing and quantity. The engine tests, without turbocharging, are conducted under non-EGR conditions and using approximately 27% EGR rate. Results with HVO are compared with results when using diesel fuel. Within the constraints of a single, representative operating point, the results highlight that when using the factory map-based injection strategy, HVO offers soot emissions below 0.015 g/kWh, a 50% reduction when compared to diesel fuel. Nitrogen oxides (NOx) emissions at the same conditions are, however, 10% higher than for diesel fuel. That correlates with higher peak in-cylinder pressures and temperatures. Advancing the pilot HVO injection reduced NOx emissions to the level of the diesel baseline, and although soot emissions increased, they remained 25% lower than with diesel. Interestingly, the two tested fuels exhibited very different responses to EGR. Generally, at 27% EGR, HVO produced twice as much soot as diesel. The heat release analysis indicates this sensitivity to EGR stems from HVO’s higher cetane number causing faster auto-ignition, resulting in less premixed combustion and hence producing more soot. Generally, HVO offered more complete combustion than diesel fuel. Regardless of pilot fuel injection strategy, CO emission was reduced by approximately 50% with HVO for both EGR and non-EGR conditions. HVO also benefits emissions of unburned hydrocarbons, in terms of both total values and also unlegislated aldehydes and aromatics.

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.

Control-Oriented Physics-Based NOX Emission Model for a Diesel Engine With Exhaust Gas Recirculation

2020 ◽  
Vol 1 (1) ◽  
Author(s):  
Saravanan Duraiarasan ◽  
Rasoul Salehi ◽  
Anna Stefanopoulou ◽  
Siddharth Mahesh ◽  
Marc Allain
Keyword(s):  
Diesel Engine ◽  
Test Procedure ◽  
Flame Temperature ◽  
Exhaust Gas Recirculation ◽  
Nox Emission ◽  
Injection Timing ◽  
Exhaust Gas ◽  
Engine Control ◽  
Gas Recirculation ◽  
The Impact

Abstract Stringent NOX emission norm for heavy duty vehicles motivates the use of predictive models to reduce emissions of diesel engines by coordinating engine parameters and aftertreatment. In this paper, a physics-based control-oriented NOX model is presented to estimate the feedgas NOX for a diesel engine. This cycle-averaged NOX model is able to capture the impact of all major diesel engine control variables including the fuel injection timing, injection pressure, and injection rate, as well as the effect of cylinder charge dilution and intake pressure on the emissions. The impact of the cylinder charge dilution controlled by the engine exhaust gas recirculation (EGR) in the highly diluted diesel engine of this work is modeled using an adiabatic flame temperature predictor. The model structure is developed such that it can be embedded in an engine control unit without any need for an in-cylinder pressure sensor. In addition, details of this physics-based NOX model are presented along with a step-by-step model parameter identification procedure and experimental validation at both steady-state and transient conditions. Over a complete federal test procedure (FTP) cycle, on a cumulative basis the model prediction was more than 93% accurate.

Reduction of NOx emissions with low viscous biofuel using exhaust gas recirculation technique

2020 ◽  
Author(s):  
Rajasekar Rajendran ◽  
J. Paul Udayan Gomez ◽  
M. Mohammed Javed ◽  
Ganesan Subbiah
Keyword(s):  
Exhaust Gas Recirculation ◽  
Nox Emissions ◽  
Exhaust Gas ◽  
Reduction Of Nox ◽  
Gas Recirculation
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