The Usefulness of Negative Valve Overlap for Gasoline Partially Premixed Combustion, PPC

2012 ◽  
Author(s):  
Patrick Borgqvist ◽  
Martin Tuner ◽  
Augusto Mello ◽  
Per Tunestal ◽  
Bengt Johansson
Keyword(s):  
Premixed Combustion ◽  
Partially Premixed Combustion ◽  
Partially Premixed ◽  
Negative Valve Overlap ◽  
Valve Overlap

The Low Load Limit of Gasoline Partially Premixed Combustion Using Negative Valve Overlap

2013 ◽  
Vol 135 (6) ◽  
Author(s):  
Patrick Borgqvist ◽  
Öivind Andersson ◽  
Per Tunestål ◽  
Bengt Johansson
Keyword(s):  
Engine Speed ◽  
Premixed Combustion ◽  
Partially Premixed Combustion ◽  
Operating Region ◽  
Load Limit ◽  
Low Load ◽  
Partially Premixed ◽  
Negative Valve Overlap ◽  
Valve Overlap ◽  
Injection Strategies

Partially premixed combustion has the potential of high efficiency and simultaneous low soot and NOx emissions. Running the engine in partially premixed combustion mode with high octane number fuels has the advantage of a longer premix period of fuel and air which reduces soot emissions, even at higher loads. The problem is the ignitability at low load and idle operating conditions. The objective is to investigate different multiple-injection strategies in order to further expand the low load limit and reduce the dependency on negative valve overlap in order to increase efficiency. The question is, what is the minimum attainable load for a given setting of negative valve overlap and fuel injection strategy. The experimental engine is a light duty diesel engine equipped with a fully flexible valve train system. The engine is run without boost at engine speed 800 rpm. The fuel is 87 RON gasoline. A turbocharger is typically used to increase the boost pressure, but at low engine speed and load the available boost is expected to be limited. The in-cylinder pressure and temperature around top-dead-center will then be too low to ignite high octane number fuels. A negative valve overlap can be used to extend the low engine speed and load operating region. But one of the problems with negative valve overlap is the decrease in gas-exchange efficiency due to heat-losses from recompression of the residual gases. Also, the potential temperature increase from the trapped hot residual gases is limited at low load due to the low exhaust gas temperature. In order to expand the low load operating region further, more advanced injection strategies are investigated.

The Low Load Limit of Gasoline Partially Premixed Combustion Using Negative Valve Overlap

2012 ◽  
Author(s):  
Patrick Borgqvist ◽  
Öivind Andersson ◽  
Per Tunestål ◽  
Bengt Johansson
Keyword(s):  
Engine Speed ◽  
Premixed Combustion ◽  
Partially Premixed Combustion ◽  
Operating Region ◽  
Load Limit ◽  
Low Load ◽  
Negative Valve Overlap ◽  
Valve Overlap ◽  
Injection Strategies ◽  
High Octane

Partially premixed combustion has the potential of high efficiency and simultaneous low soot and NOx emissions. Running the engine in PPC mode with high octane number fuels has the advantage of a longer premix period of fuel and air which reduces soot emissions, even at higher loads. The problem is the ignitability at low load and idle operating conditions. The objective is to investigate different multiple-injection strategies in order to further expand the low load limit and reduce the dependency on negative valve overlap in order to increase efficiency. The question is, what is the minimum attainable load for a given setting of negative valve overlap and fuel injection strategy. The experimental engine is a light duty diesel engine equipped with a fully flexible valve train system. The engine is run without boost at engine speed 800 rpm. The fuel is 87 RON gasoline. A turbocharger is typically used to increase the boost pressure, but at low engine speed and load the available boost is expected to be limited. The in-cylinder pressure and temperature around top-dead-center will then be too low to ignite high octane number fuels. A negative valve overlap can be used to extend the low engine speed and load operating region. But one of the problems with negative valve overlap is the decrease in gas-exchange efficiency due to heat-losses from recompression of the residual gases. Also, the potential temperature increase from the trapped hot residual gases is limited at low load due to the low exhaust gas temperature. In order to expand the low load operating region further, more advanced injection strategies are investigated.

Effects of porous media on partially premixed combustion and heat transfer in meso-scale burners fuelled with ethanol

Energy ◽  
2021 ◽  
pp. 120191
Author(s):  
Xinjian Chen ◽  
Junwei Li ◽  
Dan Zhao ◽  
Muhammad Tahir Rashid ◽  
Xinyuan Zhou ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Porous Media ◽  
Premixed Combustion ◽  
Partially Premixed Combustion ◽  
Partially Premixed ◽  
Meso Scale

Effects of Different Type of Gasoline Fuels on Heavy Duty Partially Premixed Combustion

2009 ◽  
Vol 2 (2) ◽  
pp. 71-88 ◽  
Author(s):  
Vittorio Manente ◽  
Bengt Johansson ◽  
Per Tunestal ◽  
William Cannella
Keyword(s):  
Premixed Combustion ◽  
Heavy Duty ◽  
Partially Premixed Combustion ◽  
Partially Premixed

Characterization of Partially Premixed Combustion With Ethanol: EGR Sweeps, Low and Maximum Loads

2010 ◽  
Vol 132 (8) ◽  
Author(s):  
Vittorio Manente ◽  
Bengt Johansson ◽  
Pert Tunestal
Keyword(s):  
High Efficiency ◽  
Pressure Rise ◽  
Premixed Combustion ◽  
Maximum Pressure ◽  
Pressure Rise Rate ◽  
Start Of Injection ◽  
Partially Premixed Combustion ◽  
Rise Rate ◽  
Partially Premixed ◽  
Gas Recirculation

Exhaust gas recirculation (EGR) sweeps were performed on ethanol partially premixed combustion (PPC) to show different emission and efficiency trends as compared with diesel PPC. The sweeps showed that when the EGR rate is increased, the efficiency does not diminish, HC trace is flat, and CO is low even with 45% of EGR. NOx exponentially decreases by increasing EGR while soot levels are nearly zero throughout the sweep. The EGR sweeps underlined that at high EGR levels, the pressure rise rate is a concern. To overcome this problem and keep high efficiency and low emissions, a sweep in the timing of the pilot injection and pilot-main ratio was done at ∼16.5 bars gross IMEP. It was found that with a pilot-main ratio of 50:50, and by placing the pilot at −60 with 42% of EGR, NOx and soot are below EURO VI levels; the indicated efficiency is 47% and the maximum pressure rise rate is below 10 bar/CAD. Low load conditions were examined as well. It was found that by placing the start of injection at −35 top dead center, the efficiency is maximized, on the other hand, when the injection is at −25, the emissions are minimized, and the efficiency is only 1.64% lower than its optimum value. The idle test also showed that a certain amount of EGR is needed in order to minimize the pressure rise rate.

scholarly journals Hybrid transported-tabulated chemistry for partially premixed combustion

2019 ◽  
Vol 179 ◽  
pp. 206-227 ◽  
Author(s):  
Bastien Duboc ◽  
Guillaume Ribert ◽  
Pascale Domingo
Keyword(s):  
Premixed Combustion ◽  
Partially Premixed Combustion ◽  
Tabulated Chemistry ◽  
Partially Premixed
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