Emission Reductions Through Precombustion Chamber Design in a Natural Gas, Lean Burn Engine

1992 ◽  
Vol 114 (3) ◽  
pp. 466-474 ◽  
Author(s):  
M. E. Crane ◽  
S. R. King
Keyword(s):  
Natural Gas ◽  
Exhaust Emissions ◽  
Hydrocarbon Emissions ◽  
Oxides Of Nitrogen ◽  
Lean Burn ◽  
Precombustion Chamber ◽  
Engine Efficiency ◽  
Chamber Design ◽  
And Control ◽  
Total Hydrocarbons

A study was conducted to evaluate the effects of various precombustion chamber design, operating, and control parameters on the exhaust emissions of a natural gas engine. Analysis of the results showed that engine-out total hydrocarbons and oxides of nitrogen (NOx) can be reduced, relative to conventional methods, through prechamber design. More specifically, a novel staged prechamber yielded significant reductions in NOx and total hydrocarbon emissions by promoting stable prechamber and main chamber ignition under fuel-lean conditions. Precise fuel control was also critical when balancing low emissions and engine efficiency (i.e., fuel economy). The purpose of this paper is to identify and explain positive and deleterious effects of natural gas prechamber design on exhaust emissions.

Effect of Hydrogen Content in Hydrogen Natural-Gas Fuel Mixtures on Emissions in a Lean-Burn IC Engine

2005 ◽  
Author(s):  
Paul A. Salanki ◽  
James S. Wallace
Keyword(s):  
Natural Gas ◽  
Hydrogen Content ◽  
Load Condition ◽  
Hydrocarbon Emissions ◽  
Nox Emissions ◽  
Lean Burn ◽  
Engine Efficiency ◽  
Hc Emissions ◽  
Fuel Mixtures ◽  
The Impact

The influence of hydrogen content in hydrogen-natural gas fuel mixtures on the emissions of a lean-burn spark ignition engine has been examined under representative operating conditions, a mid load and a high load. The hydrogen content in the fuel gas mixtures was varied from 0 to 30% with the balance made up of natural gas. The primary effect on emissions was to influence the tradeoff between NOx and hydrocarbon emissions. At the mid-load condition, increasing the hydrogen content from 0 to 15% at constant equivalence ratio reduced the HC emissions by 80% with little change in NOx emissions. Increasing from 15 to 30% hydrogen content reduced the HC emissions a further 50% but increased the NOx emissions by 16%. At the high load condition, the overall result of increasing the hydrogen content was to increase the NOx emissions substantially without significantly reducing the HC emissions. The impact of increasing hydrogen content on engine efficiency is similar to the impact on hydrocarbon emissions. At the mid-load condition, engine efficiency was increased by increasing hydrogen content, but with diminishing returns. An increase from 0 to 5% hydrogen content provides a significant benefit under marginal combustion conditions but further increases in hydrogen content are less effective.

Variable Composition Hydrogen/Natural Gas Mixtures for Increased Engine Efficiency and Decreased Emissions

1999 ◽  
Vol 122 (1) ◽  
pp. 135-140 ◽  
Author(s):  
R. Sierens ◽  
E. Rosseel
Keyword(s):  
Natural Gas ◽  
Exhaust Emissions ◽  
Pure Hydrogen ◽  
Operating Characteristics ◽  
Load Range ◽  
Engine Operation ◽  
High Hydrogen ◽  
Hydrogen Addition ◽  
Engine Efficiency ◽  
Engine Operating Condition

It is well known that adding hydrogen to natural gas extends the lean limit of combustion and that in this way extremely low emission levels can be obtained: even the equivalent zero emission vehicle (EZEV) requirements can be reached. The emissions reduction is especially important at light engine loads. In this paper results are presented for a GM V8 engine. Natural gas, pure hydrogen and different blends of these two fuels have been tested. The fuel supply system used provides natural gas/hydrogen mixtures in variable proportion, regulated independently of the engine operating condition. The influence of the fuel composition on the engine operating characteristics and exhaust emissions has been examined, mainly but not exclusively for 10 and 20 percent hydrogen addition. At least 10 percent hydrogen addition is necessary for a significant improvement in efficiency. Due to the conflicting requirements for low hydrocarbons and low NOx, determining the optimum hythane composition is not straight-forward. For hythane mixtures with a high hydrogen fraction, it is found that a hydrogen content of 80 percent or less guarantees safe engine operation (no backfire nor knock), whatever the air excess factor. It is shown that to obtain maximum engine efficiency for the whole load range while taking low exhaust emissions into account, the mixture composition should be varied with respect to engine load. [S0742-4795(00)02001-9]

Lessons From the Conversion of a Heavy-Duty Compression Ignition Engine to Natural Gas Spark Ignition Operation

2020 ◽  
Author(s):  
Jinlong Liu ◽  
Christopher Ulishney ◽  
Cosmin E. Dumitrescu
Keyword(s):  
Natural Gas ◽  
Fuel Injection ◽  
Volume Ratio ◽  
Spark Ignition ◽  
Point Of View ◽  
Injection System ◽  
Compression Ignition ◽  
Compression Ignition Engine ◽  
Lean Burn ◽  
Engine Efficiency

Abstract Partial conversion of the large inventory of compression-ignition engines to natural-gas (NG) spark-ignition lean-burn operation can reduce U.S. dependence on imported petroleum and enhance national energy security. This paper describes some of the observations made during such an engine conversion and proposes some solutions to alleviate some of the potential issues. The engine conversion in this study consisted from replacing the diesel injector with a spark plug and adding a port fuel injection system for NG delivery. The results indicated that the retrofitted engine performed reliably at lean-burn conditions, despite the different combustion characteristics compared to conventional SI engines. However, the squish region will trap an important fuel fraction (∼30%) and experience less-optimal burning conditions, hence a slower burning rate. This affected the engine efficiency and increased the unburned hydrocarbon and carbon monoxide emissions. From a combustion point of view, the operation of such converted engines can be optimized by increasing the bowl-to-squish volume ratio, optimizing the piston shape (e.g., by removing the central protrusion and avoiding 90-degree edges inside the bowl). The original compression ratio may also need to be reduced to avoid knocking. Moreover, direct gas injection and/or intake charging will increase the volumetric efficiency, which will benefit engine efficiency and emissions.

Comparison of Emissions and Efficiency of a Turbocharged Lean-Burn Natural Gas and Hythane-Fueled Engine

1997 ◽  
Vol 119 (1) ◽  
pp. 218-226 ◽  
Author(s):  
J. F. Larsen ◽  
J. S. Wallace
Keyword(s):  
Natural Gas ◽  
Specific Energy Consumption ◽  
Oxides Of Nitrogen ◽  
Heavy Duty ◽  
Lean Burn ◽  
Clear Trend ◽  
Engine Operation ◽  
Spark Timing ◽  
Test Engine ◽  
Carbon Dioxide Co2

An experiment was conducted to evaluate the potential for reduced exhaust emissions and improved efficiency, by way of lean-burn engine fuelling with hydrogen supplemented natural gas (Hythane). The emissions and efficiency of the Hythane fuel (15 percent hydrogen, 85 percent natural gas by volume), were compared to the emissions and efficiency of pure natural gas using a turbocharged, spark ignition, 3.1 L, V-6 engine. The feasibility of heavy duty engine fueling with Hythane was assessed through testing conducted at engine speed and load combinations typical of heavy-duty engine operation. Comparison of the efficiency and emissions at MBT spark timing revealed that Hythane fueling of the test engine resulted in consistently lower brake specific energy consumption and emissions of total hydrocarbons (THC), carbon monoxide (CO), and carbon dioxide (CO2), at a given equivalence ratio. There was no clear trend with respect to MBT oxides of nitrogen (NOx) emissions. It was also discovered that an improved NOx-THC tradeoff resulted when Hythane was used to fuel the test engine. Consequently, Hythane engine operating parameters can be adjusted to achieve a concurrent reduction in NOx and THC emissions relative to natural gas fueling.

Lean Burn Natural Gas Fueled S.I.Engine and Exhaust Emissions

1995 ◽  
Author(s):  
K.S. Varde ◽  
N. Patro ◽  
Ken Drouillard
Keyword(s):  
Natural Gas ◽  
Exhaust Emissions ◽  
Lean Burn ◽  
Gas Fueled

Correlation Between Speciated Hydrocarbon Emissions and Flame Ionization Detector Response for Gasoline/Alcohol Blends

2011 ◽  
Vol 133 (8) ◽  
Author(s):  
Thomas Wallner
Keyword(s):  
Exhaust Emissions ◽  
Flame Ionization Detector ◽  
Detector Response ◽  
Hydrocarbon Emissions ◽  
Response Factor ◽  
Oxides Of Nitrogen ◽  
Ionization Detector ◽  
Flame Ionization ◽  
Certification Testing ◽  
Exhaust Stream

The U.S. renewable fuel standard has made it a requirement to increase the production of ethanol and advanced biofuels to 36 billion by 2022. Ethanol will be capped at 15 billion, which leaves 21 billion to come from other sources such as butanol. Butanol has a higher energy density and lower affinity for water than ethanol. Moreover, alcohol fueled engines in general have been shown to positively affect engine-out emissions of oxides of nitrogen and carbon monoxide compared with their gasoline fueled counterparts. In light of these developments, the variety and blend levels of oxygenated constituents is likely to increase in the foreseeable future. The effect on engine-out emissions for total hydrocarbons is less clear due to the relative insensitivity of the flame ionization detector (FID) toward alcohols and aldehydes. It is well documented that hydrocarbon (HC) measurement using a conventional FID in the presence of oxygenates in the engine exhaust stream can lead to a misinterpretation of HC emissions trends for alcohol fuel blends. Characterization of the exhaust stream for all expected hydrocarbon constituents is required to accurately determine the actual concentration of unburned fuel components in the exhaust. In addition to a conventional exhaust emissions bench, this characterization requires supplementary instrumentation capable of hydrocarbon speciation and response factor independent quantification. Although required for certification testing, this sort of instrumentation is not yet widely available in engine development facilities. Therefore, an attempt is made to empirically determine FID correction factors for oxygenate fuels. Exhaust emissions of an engine fueled with several blends of gasoline and ethanol, n-butanol and iso-Butanol were characterized using both a conventional FID and a Fourier transform infrared. Based on these results, a response factor predicting the actual hydrocarbon emissions based solely on FID results as a function of alcohol type and content is presented. Finally, the correlation derived from data presented in this study is compared with equations and results found in the literature.

Potential Reduction of Fugitive Methane Emissions at Compressor Stations and Storage Facilities Powered by Natural Gas Engines

2014 ◽  
Author(s):  
Derek Johnson ◽  
April Covington
Keyword(s):  
Natural Gas ◽  
Methane Emissions ◽  
Hydrocarbon Emissions ◽  
Storage Tanks ◽  
Lean Burn ◽  
Potential Reduction ◽  
Natural Gas Engines ◽  
Crankcase Ventilation ◽  
And Storage ◽  
Storage Facilities

The American Gas Association (AGA) and the United States (US) Energy Information Administration (EIA) report that natural gas reserves, production, and consumption are increasing. Current estimates show over 100 years worth of recoverable reserves. As production increases, the natural gas pipeline interstate will grow or at least experience increased throughput. With the industry expanding at rapid rates and the high global warming potential of methane (21 over a 100 year period), it is important to identify potential sources for reductions in fugitive methane emissions. This research group conducted leak and loss audits at five natural gas compressor station and storage facilities. The majority of methane losses were associated with the operation of the lean-burn, natural gas engines (open crankcases, exhaust), compressor seal vents, and open liquid storage tanks. This paper focuses on the potential reduction in fugitive methane emissions of the discovered industry weaknesses through application of various proven technologies. As engines are not perfectly sealed, blow-by of intake air, fuel, and combustion gases occurs past the piston rings. In order to prevent a build-up of pressure within the crankcase, it must be vented. Diesel engines have lower hydrocarbon emissions from their crankcases due to the short duration of fuel addition after compression of the intake charge. Lean-burn, natural gas engines, like conventional gasoline engines, compress both the fuel and intake air during the compression stroke. During the 1960s, many passenger vehicles adopted positive crankcase ventilation (PCV) or closed crankcase ventilation (CCV) systems to reduce significantly hydrocarbon emissions from engines. Currently, some heavy-duty on-road engines still have open crankcase systems and most off-road engines have crankcases simply vented to the atmosphere. In this paper, researchers will examine the potential reduction in methane emissions that could be realized with the installation of retrofitted CCV systems at these locations. In addition to the reduction of methane losses from the crankcase, it is realized that with proper plumbing, flow control, and safety parameters, all of the losses typically vented to atmosphere could be ducted into the engine intake for combustion. Preliminary results show that applications of closed crankcase systems could reduce emissions from these sites by 1–11% while modifying these systems to include the losses from compressor seal vents and storage tanks could yield potential reductions in methane emissions by 10–57%.

scholarly journals Measurement of Exhaust Emissions From Two J-58 Engines at Simulated Supersonic Cruise Flight Conditions

1976 ◽  
Author(s):  
J. D. Holdeman
Keyword(s):  
Carbon Monoxide ◽  
Power Level ◽  
Exhaust Emissions ◽  
Flight Speed ◽  
Hydrocarbon Emissions ◽  
Oxides Of Nitrogen ◽  
Test Conditions ◽  
Simulated High Altitude ◽  
Unburned Hydrocarbons ◽  
Cruise Flight

Emissions of total oxides of nitrogen, unburned hydrocarbons, carbon monoxide, and carbon dioxide from two J-58 afterburning turbojet engines at simulated high-altitude flight conditions are reported. Test conditions included flight speeds from Mach 2 to 3 at altitudes from 16 to 23 km. For each flight condition, exhaust measurements were made for four or five power levels from maximum power without afterburning through maximum afterburning. The data show that exhaust emissions vary with flight speed, altitude, power level, and radial position across the exhaust. Oxides of nitrogen (NOx) emissions decreased with increasing altitude and increased with increasing flight speed. NOx emission indices with afterburning were less than half the value without afterburning. Carbon monoxide and hydrocarbon emissions increased with increasing altitude and decreased with increasing flight speed. Emissions of these species were substantially higher with afterburning than without.

Precombustion Chamber Design for Emissions Reduction From Large Bore NG Engines

2010 ◽  
Vol 132 (12) ◽  
Author(s):  
Dean J. Simpson ◽  
Daniel B. Olsen
Keyword(s):  
Natural Gas ◽  
Combustion Stability ◽  
Nozzle Geometry ◽  
Oxides Of Nitrogen ◽  
Lean Burn ◽  
Engine Operation ◽  
Chamber Volume ◽  
Fuel Delivery ◽  
Design Variables ◽  
Partial Load

Precombustion chambers (PCCs) are an ignition technology for large bore, natural gas engines, which can extend the lean operating limit through improved combustion stability. Previous research indicates that the PCC is responsible for a significant portion of engine-out emissions, especially near the lean limit of engine operation. In this work, six concept PCC designs are developed with the objective of reducing engine-out emissions, focusing on oxides of nitrogen (NOx). The design variables include chamber geometry, chamber volume, fuel delivery, nozzle geometry, and material thermal conductivity. The concepts are tested on a single cylinder of a large bore, two-stroke cycle, lean burn, natural gas compressor engine, and the results are compared with stock PCC performance. The pollutants of interest include NOx, carbon monoxide, total hydrocarbons, and volatile organic compounds (VOCs). The results indicate that PCC volume has the largest effect on the overall NOx–CO tradeoff. Multiple nozzles and electronic PCC fuel control were found to enhance main chamber combustion stability, particularly at partial load conditions. The PCC influence on VOCs was insignificant; rather, VOCs were found to be heavily dependent on fuel composition.

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