On Blow-by Aerosol Sources in a Single-Cylinder Crankcase Environment

2021 ◽  
Author(s):  
N. Nowak ◽  
K. Scheiber ◽  
C. Stieler ◽  
M. T. Heller ◽  
J. Pfeil ◽  
...  
Keyword(s):  
Ventilation System ◽  
Formation Mechanisms ◽  
Minor Effect ◽  
Piston Rings ◽  
Bulk Oil ◽  
Single Cylinder ◽  
Aerosol Generation ◽  
Crankcase Ventilation ◽  
Aerosol Sources ◽  
Peak Pressures

Abstract Crankcase aerosol contributes to the particulate matter (PM) emissions of combustion engines equipped with an open crankcase ventilation system. In case of closed crankcase ventilation, the aerosol forms deposits that diminish engine efficiency, performance, and reliability. Such issues are best avoided by highly efficient filters combined with in-engine reduction strategies based on a quantitative understanding of aerosol sources and formation mechanisms in a crankcase environment. This paper reports key findings from a study of aerosol spectra in the range of 0.01 μm to 10 μm obtained from a 1.3-L single-cylinder engine under well-defined conditions. Supermicron particles were formed mainly by cooling jet break-up when the piston was positioned in TDC, while at BDC aerosol generation decreased by about 90 % because the oil jet was short and thus stable. Motoring the engine yielded an additional peak around 0.7 μm. It is associated with oil atomization at the piston rings and increased strongly with cylinder peak pressure. No significant contribution of the bearings could be identified at peak pressures below 116 bar. Engine speed had only a minor effect on aerosol properties. Operating the engine in fired mode increased the submicron aerosol concentration substantially, presumably because high(er) peak pressures boost aerosol generation at the piston rings, and because additional particles may have formed from recondensing oil vapor generated at hotspots. Soot or ash aerosols could not be identified in the crankcase aerosol, because they may have been integrated into the bulk oil.

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.

Blow-By Truck Application: Electrically Driven Cone Stack Separator for Crankcase Ventilation

2007 ◽  
Author(s):  
Gerd Kissner ◽  
Hartmut Sauter
Keyword(s):  
Separation Efficiency ◽  
Ventilation System ◽  
Motor Vehicles ◽  
Cylinder Wall ◽  
Oil Consumption ◽  
Control Laws ◽  
Crankcase Ventilation ◽  
Oil Fraction ◽  
Air Intake ◽  
Oil Mist

Dealing with the blow-by gas from reciprocating engine is a bigger challenge nowadays due to strict emission control laws and design limitations. Blow-by gas originates between the piston or piston rings and the cylinder wall and is charged with oil when it leaves the crankcase. In a closed crankcase ventilation system these blow-by gases are drawn from the crankcase into the air intake. The oil mist separator (OMS) retains a fraction of the liquid oil and returns the retained oil fraction back to the oil sump. Thus, the oil mist separator reduces oil consumption and emissions. Electrically driven cone stack separators have high separation efficiency, small differential pressure, arbitrary mounting position and low power consumption. In addition to that, the electrically driven cone stack separator has also advantageous control characteristics. Since commercial motor vehicles already have high electrical system requirements a Mechatroic concept is presented here which was developed to be maintenance-free over the lifetime of the engine. This is achieved by detailed design and choice of special materials. In this paper, the construction and application of the novel oil mist separator system for trucks are discussed in detail.

scholarly journals Aerosol transport over the Gangetic basin during ISRO-GBP land campaign-II

2008 ◽  
Vol 26 (3) ◽  
pp. 431-440 ◽  
Author(s):  
M. Aloysius ◽  
M. Mohan ◽  
K. Parameswaran ◽  
S. K. George ◽  
P. R. Nair
Keyword(s):  
Power Plants ◽  
Geometric Mean ◽  
Thermal Power ◽  
Thermal Power Plants ◽  
Ganga Basin ◽  
Gangetic Plain ◽  
Aerosol Generation ◽  
Aerosol Sources ◽  
Head Bay Of Bengal ◽  
Indo Gangetic Plain

Abstract. MODIS (Moderate Resolution Imaging Spectroradiometer) Level-3 aerosol optical depth (AOD) data and NCEP (National Centre for Environmental Prediction) reanalysis winds were incorporated into an aerosol flux continuity equation, for a quantitative assessment of the sources of aerosol generation over the Ganga basin in the winter month of December 2004. Preliminary analysis on the aerosol distribution and wind fields showed wind convergence to be an important factor which, supported by the regional topography, confines aerosols in a long band over the Indo Gangetic plain (IGP) stretching from the west of the Thar desert into the Head-Bay-of-Bengal. The prevailing winds of the season carry the aerosols from Head-Bay-of-Bengal along the east coast as far as the southern tip of the peninsular India. A detailed examination of MODIS data revealed significant day-to-day variations in aerosol loading in localised pockets over the central and eastern parts of the Indo Gangetic plain during the second half of December, with AOD values even exceeding unity. Aerosols over the Ganga basin were dominated by fine particles (geometric mean radius ~0.05–0.1μm) while those over the central and western India were dominated by large particles (geometric mean radius ~0.3–0.7μ). Before introducing it into the flux equation, the MODIS derived AOD was validated through a comparison with the ground-based measurements collected at Kharagpur and Kanpur; two stations located over the Ganga basin. The strength of the aerosol generation computed using the flux equation indicated the existence of aerosol sources whose locations almost coincided with the concentration of thermal power plants. The quantitative agreement between the source strength and the power plant concentration, with a correlation coefficient 0.85, pointed to thermal power plants as substantial contributors to the high aerosol loading over the Ganga Basin in winter. The layout of aerosol sources also nearly matched the spatial distribution of the Respirable Suspended Particulate Matter (RSPM), derived from the Central Pollution Control Board (CPCB) data, lending additional support to our inference.

scholarly journals Comparison of four diesel engines with regard to blow-by aerosol properties as a basis for reduction strategies based on engine design and operation

2021 ◽  
Author(s):  
Kai-Michael Scheiber ◽  
Niclas Nowak ◽  
Magnus Lukas Lorenz ◽  
Jürgen Pfeil ◽  
Thomas Koch ◽  
...  
Keyword(s):  
Particle Size ◽  
Diesel Engines ◽  
Engine Speed ◽  
Total Concentration ◽  
Ventilation System ◽  
Sampling System ◽  
Brake Mean Effective Pressure ◽  
Engine Design ◽  
Aerosol Sources ◽  
Generation Mechanisms

AbstractUnderstanding how engine design and operation affect blow-by aerosol characteristics is key to reducing the emission of particulate matter (PM) via the crankcase ventilation system. To this end, representative aerosol data from four different diesel engines are compared on the basis of brake mean effective pressure (BMEP) and engine speed. The data were obtained from comparable sampling positions, using the same sampling system and optical particle counter. The discussion is based on the narrow particle size range of 0.4–1.3 µm, chosen for its significance with regard to blow-by aerosol sources, as well as for the challenges it poses for separation systems. Key findings include particle size distributions (PSD) of virtually identical shape, indicating that these engines share the same aerosol sources and underlying generation mechanisms. However, absolute concentrations differed by a factor of about six, presumably due to differences in engine design, which in turn affect key parameters such as temperature, pressure and flow rates. At BMEPs ≤ 10 bar all engines exhibited similarly low aerosol concentrations. With increasing BMEP the concentration rose exponentially. The engine with the smallest rise and the lowest total concentration featured an aluminum alloy piston, the smallest displacement, the lowest peak BMEP as well as the lowest maximum oil temperature. At maximum torque the aerosol concentration scaled fairly linearly with engine displacement. Increasing the engine speed had a minor impact on aerosol concentrations but affected blow-by flows, hence leading to a rise of aerosol mass flows. Within the limits of this comparative measurement studies, three generation mechanisms are provided for blow-by aerosols.

Optimizing Crankcase Ventilation System of Gasoline Engine

2011 ◽  
Vol 58-60 ◽  
pp. 171-176
Author(s):  
Ming Jiang Hu
Keyword(s):  
Gasoline Engine ◽  
Ventilation System ◽  
Flow Characteristics ◽  
Gas Leakage ◽  
Working Model ◽  
Crankcase Ventilation ◽  
Analog Control ◽  
Test Platform ◽  
Fluid Properties ◽  
Test Result

Based on the design goals of the gasoline engine crankcase ventilation system, the features and the layout were described on the gasoline engine crankcase ventilation system, the working model was established on the gasoline engine crankcase ventilation system; using the fluid properties and the mathematical calculation method, the optimizing strategy was proposed on the piston gas leakage, the influencing factors were analyzed on the gasoline engine crankcase vacuum, the design strategy of the flow characteristics was developed on the PCV valve. Using analog control test platform of the gasoline engine, the tests were made on the piston gas leakage, the crankcase vacuum and PCV valve flow characteristics of the gasoline engine crankcase ventilation system. The test result showed that the optimized maximum piston leakage flow was 14L/min; the increasing rates of the optimized intake pipe and crankcase vacuum average were according 5.6% and 8.0%. This could indicate that the working model on the gasoline engine crankcase ventilation system was correct; the proposed strategies on the piston gas leakage, the crankcase vacuum and PCV valve flow characteristics were feasible in the gasoline engine crankcase ventilation system.

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