Liquid Fuel Effects on the Unburned Hydrocarbon Emissions of a Small Engine

2006 ◽  
Author(s):  
V. M. Salazar ◽  
J. B. Ghandhi
Keyword(s):  
Liquid Fuel ◽  
Hydrocarbon Emissions ◽  
Unburned Hydrocarbon ◽  
Fuel Effects

Liner Design to Reduce Unburned Hydrocarbon Exhaust Emissions

2018 ◽  
Author(s):  
Paul S. Wang ◽  
Allen Y. Chen
Keyword(s):  
Natural Gas ◽  
Ventilation System ◽  
Hydrocarbon Emissions ◽  
Tracer Technique ◽  
Oil Consumption ◽  
Natural Gas Engines ◽  
Unburned Hydrocarbon ◽  
Crankcase Ventilation ◽  
Unburned Fuel ◽  
Careful Design

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.

Reduction of Gaseous Emission From Turbine Combustor

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.

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

2009 ◽  
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.

Simulation of Gas Turbine Reacting Flows

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.

Two-Stage Lean-Burn Combustion Inside a Natural-Gas Spark-Ignition Engine With a Bowl-in-Piston Chamber

2019 ◽  
Author(s):  
Jinlong Liu ◽  
Cosmin E. Dumitrescu
Keyword(s):  
Natural Gas ◽  
Combustion Chamber ◽  
Combustion Process ◽  
Spark Ignition ◽  
Spark Ignition Engine ◽  
Intake Manifold ◽  
Hydrocarbon Emissions ◽  
Fuel Injector ◽  
Unburned Hydrocarbon ◽  
Piston Chamber

Abstract The conversion of existing diesel engines to spark ignition (SI) operation by adding a low-pressure injector in the intake manifold for fuel delivery and replacing the original high-pressure fuel injector with a spark plug to initiate and control the combustion process can reduce U.S. dependence on petroleum imports and increase natural gas (NG) applications in heavy-duty transportation sectors. Since the conventional diesel combustion chamber (i.e., flat-head-and-bowl-in-piston-chamber) creates high turbulence, the converted NG SI engine can operate leaner with stable and repeatable combustion process. However, existing literatures point to a long late-combustion duration and increased unburned hydrocarbon emissions in such retrofitted engines that maintained the original combustion chamber. Consequently, the main objective of this paper was to report recent findings of NG combustion characteristics inside a bowl-in-piston combustion chamber that will add to the general understanding of the phenomena. The new results indicated that the premixed NG burn inside the bowl-in-piston combustion chamber will separate into a bowl-burn and a squish-burn processes in terms of burning location and timing. The slow burning event in the squish region explains the low slope of the burn rate towards the end of combustion in existing studies (hence the longer late-combustion period). In addition, the less-favorable conditions for the combustion in the squish region explained the increased carbon monoxide and unburned hydrocarbon emissions.

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