On the origin of Unburned Hydrocarbon Emissions in a Wall Guided, Low NOx Diesel Combustion System

Large natural gas engines that introduce premixed fuel and air into the engine cylinders allow a small fraction of fuel to evade combustion, which is undesirable. The premixed fuel and air combust via flame propagation. Ahead of the flame front, the unburned fuel and air are driven into crevices, where conditions are not favorable for oxidation. The unburned fuel is a form of waste and a source of potent greenhouse gas emissions. A concept to vent unburned fuel into the crankcase through built-in slots in the liner during the expansion stroke has been tested. This venting process occurs before the exhaust valve opens and the unburned fuel sent into the crankcase can be recycled to the intake side through a closed crankcase ventilation system. The increased communication between the cylinder and the crankcase changes the ring pack dynamics, which results in higher oil consumption. Oil consumption was measured using a sulfur tracer technique. Careful design is required to achieve the best tradeoff between reductions in unburned hydrocarbon emissions and oil control.

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Unburned Hydrocarbon Emissions from Stratified Charge Direct Injection Engines

10.4271/2003-01-3099 ◽

2003 ◽

Cited By ~ 3

Author(s):

James Hilditch ◽

Zhiyu Han ◽

Top Chea

Keyword(s):

Direct Injection ◽

Hydrocarbon Emissions ◽

Direct Injection Engines ◽

Stratified Charge ◽

Unburned Hydrocarbon

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A Lean Burn Low Emissions Gas Engine for Co-Generation

Proceedings of the Institution of Mechanical Engineers Part A Journal of Power and Energy ◽

10.1243/pime_proc_1996_210_033_02 ◽

1996 ◽

Vol 210 (3) ◽

pp. 203-211 ◽

Cited By ~ 2

Author(s):

K J S Mendis ◽

C R Stone ◽

N Ladommatos ◽

M Daragheh

Keyword(s):

Combustion Model ◽

Hydrocarbon Emissions ◽

Combustion System ◽

High Compression Ratio ◽

Specific Mass ◽

Lean Burn ◽

Gas Engine ◽

Natural Gas Engine ◽

System A ◽

Brake Mean Effective Pressure

This paper presents the rationale behind a fast burn high compression ratio (FBHCR) combustion system intended for use in a lean burn natural gas engine. Comparisons are made between the FBHCR combustion system, predictions made by a two-zone combustion model and measurements from the original combustion system, for the brake efficiency, brake mean effective pressure and the brake specific NOx emissions. Experimental measurements of the unburnt hydrocarbon emissions, the burn duration and the cycle-by-cycle variations in combustion are also discussed from the two combustion systems. The results show how the conflicting aims of low emissions and low fuel consumption can be satisfied by using a lean burn combustion system. A comparison is also made between the following ways of expressing the exhaust emissions: volumetric, brake specific, mass per megajoule of fuel and gravimetric referenced to a specified oxygen level.

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Reduction of Gaseous Emission From Turbine Combustor

Heat Transfer: Volume 1 ◽

10.1115/ht2005-72749 ◽

2005 ◽

Author(s):

R. S. Amano ◽

J. Xie ◽

Shyam Singh ◽

R. E. Peck

Keyword(s):

Heat Transfer ◽

Porous Layer ◽

Operating Conditions ◽

Ceramic Foam ◽

Spray Combustion ◽

Hydrocarbon Emissions ◽

Flame Zone ◽

Enhanced Heat Transfer ◽

Firing Rates ◽

Unburned Hydrocarbon

A study of spray combustion with porous inserts was performed using an on-axis fuel used in a concentric Jet-A. Combustion performance was evaluated by measuring exhaust emissions and gaseous temperatures for different operating conditions with and without ceramic foam inserts. The results indicated that the enhanced heat transfer in the flame zone could reduce nitrogen oxides and unburned hydrocarbon emissions. Placing a second porous layer downstream could yield further reductions in both emissions. The results for different firing rates and equivalence ratios revealed the residence time in the porous layer is an important factor in controlling the combustor performance.

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Reduction of Nitric Oxide Emission From a SI Engine by Water Injection at the Intake Runner

Volume 3: Combustion Science and Engineering ◽

10.1115/imece2009-12517 ◽

2009 ◽

Cited By ~ 6

Author(s):

Jun-Kai Wang ◽

Jing-Lun Li ◽

Ming-Hsun Wu ◽

Rong-Horng Chen

Keyword(s):

Gasoline Engine ◽

Fuel Injection ◽

Effective Means ◽

Water Injection ◽

Nox Emission ◽

Injection System ◽

Hydrocarbon Emissions ◽

Fuel Injector ◽

Unburned Hydrocarbon ◽

Nitric Oxide Emission

The effects of pulsed water injection at the intake port of a modern port fuel injection gasoline engine were investigated. A port water injection system was developed and the water injector was installed on the intake runner of the single cylinder motorcycle engine at a location upstream of the fuel injector. The results show that with a water-gasoline injection ratio of 1, more than 80% of NOx emission can be removed. The trade-off was a 25% reduction in torque output at 4000 rpm and 20% throttle opening; however, the decrease on torque can be controlled to be within 5% by reducing water-gasoline mass ratios to less than 0.6. We also performed NOx emission modeling using one-dimensional gas dynamics code with extended Zeldovich mechanism, and consistent results were found between numerical prediction and experimental measurements. The port water injection approach appears to be an effective means for reducing NOx emission from a gasoline engine at low speed and high load conditions without largely sacrificing the performances on torque output and unburned hydrocarbon emissions.

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Simulation of Gas Turbine Reacting Flows

ASME 2005 Power Conference ◽

10.1115/pwr2005-50198 ◽

2005 ◽

Author(s):

R. S. Amano ◽

J. Xie

Keyword(s):

Porous Layer ◽

Reacting Flows ◽

Operating Conditions ◽

Ceramic Foam ◽

Spray Combustion ◽

Hydrocarbon Emissions ◽

Flame Zone ◽

Enhanced Heat Transfer ◽

Firing Rates ◽

Unburned Hydrocarbon

A study of spray combustion with porous inserts was performed using an on-axis fuel used in a concentric Jet-A. Combustion performance was evaluated by measuring exhaust emissions and flame temperatures for different operating conditions with and without ceramic foam inserts of various properties. The results indicated that the enhanced heat transfer in the flame zone could reduce nitrogen oxides and unburned hydrocarbon emissions. Placing a second porous layer downstream could yield further reductions in both emissions. The results for different firing rates and equivalence ratios revealed the residence time in the porous layer is an important factor regulating combustor performance.

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