scholarly journals An Investigation of Unburned Hydrocarbon Emissions in Wall Guided, Low Temperature Diesel Combustion

2008 ◽  
Vol 63 (4) ◽  
pp. 433-459 ◽  
Author(s):  
J. Kashdan ◽  
S. Mendez ◽  
G. Bruneaux
Keyword(s):  
Low Temperature ◽  
Hydrocarbon Emissions ◽  
Diesel Combustion ◽  
Unburned Hydrocarbon

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.

A Study of the Transition Between Lean Conventional Diesel Combustion and Lean, Premixed, Low-Temperature Diesel Combustion

2007 ◽  
Author(s):  
Stephen Busch ◽  
Stanislav V. Bohac ◽  
Dennis N. Assanis
Keyword(s):  
Diesel Engine ◽  
Low Temperature ◽  
Flow Model ◽  
Transient Behavior ◽  
Diesel Combustion ◽  
Combustion Modes ◽  
Lean Premixed ◽  
Release Analysis ◽  
Separation Behavior ◽  
No Emissions

New diesel combustion modes face difficult challenges with respect to engine-out emissions and transient behavior. Transitions between lean conventional diesel combustion and lean, premixed, low-temperature diesel combustion are investigated with an automotive diesel engine. Effects of fuel pressure on transitional cycles are investigated. Cycle-by-cycle heat release analysis is performed and an exhaust mass flow model is used to obtain cycle-averaged NO concentrations. The behavior of combustion progression and NO emissions during the transitions are discussed. Observed cool-flame separation behavior is identified and explained.

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