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]

The Effects of Hydrogen Addition on Natural Gas Engine Operation

1993 ◽  
Author(s):  
Michael R. Swain ◽  
Mirza J. Yusuf ◽  
Zafer Dülger ◽  
Matthew N. Swain
Keyword(s):  
Natural Gas ◽  
Engine Operation ◽  
Gas Engine ◽  
Natural Gas Engine ◽  
Hydrogen Addition

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.

Theoretical Investigation of the Factors Affecting the Performance of a High Speed DI Diesel Engine Fuelled With Natural Gas

2008 ◽  
Author(s):  
Roussos G. Papagiannakis ◽  
Elias A. Yfantis ◽  
Dimitrios T. Hountalas ◽  
Theodoros C. Zannis
Keyword(s):  
Diesel Engine ◽  
Natural Gas ◽  
Diesel Fuel ◽  
High Speed ◽  
Engine Performance ◽  
Exhaust Emissions ◽  
Performance Characteristics ◽  
Gaseous Fuels ◽  
Engine Efficiency ◽  
Hc Emissions

Reduction of exhaust emissions is a major research task in diesel engine development in view of increasing concern regarding environmental protection and stringent exhaust gas regulations. Simultaneous reduction of NOx emissions and particulate matter is quite difficult due to the soot/NOx trade-off and is often accompanied by fuel consumption penalties. Towards this aim, automotive engineers have proposed various solutions, one of which is the use of alternative gaseous fuels as a supplement for the commercial liquid diesel fuel. This type of engine, which operates fuelled simultaneously with conventional diesel oil and gaseous fuel, is called “dual fuel” diesel engine. Among alternative gaseous fuels, natural gas is considered to be quite promising due to its low cost and its higher auto-ignition temperature compared to other gaseous fuels facilitating thus its use on existing diesel engines. Previous research studies revealed that natural gas/diesel engine operation results in deterioration of brake engine efficiency, CO and HC emissions compared to conventional diesel fuel operation. In attempt to curtail these negative effects, various theoretical and experimental studies were carried out examining the influence of various parameters such as pilot fuel quantity, diesel fuel injection timing advance and intake charge conditions on “dual fuel” engine performance characteristics and pollutant emissions. However, there are more to know about the proper combination of these engine parameters to attain the optimum results regarding reduction of CO and HC emissions without further deteriorating, if not improving, brake engine efficiency. Hence, in the present study, a theoretical investigation is conducted using an engine simulation model to examine the effect of the aforementioned parameters on performance and exhaust emissions of a natural gas/diesel engine. Predictions are produced for a high-speed natural gas/diesel engine performance characteristics and NO, CO and Soot emissions at diverse engine speeds and loads using a comprehensive two-zone combustion model. The main objective of this comparative assessment is to elaborate the relative impact of each one of the above mentioned parameters on engine performance characteristics and exhaust emissions. Furthermore, an endeavor is made to determine the optimum combinations of these engine operational parameters. The conclusions of this study may be proven to be considerably valuable for the application of this technology on existing DI diesel engines.

Use of Hydrogen and Hydrogen Mixtures in Gas Engines and Potentials of NOx Emissions

2005 ◽  
Author(s):  
Gu¨nther Herdin ◽  
Friedrich Gruber ◽  
Johann Klausner ◽  
Reinhard Robitschko ◽  
Diethard Plohberger
Keyword(s):  
Natural Gas ◽  
Laminar Flame ◽  
Gas Mixtures ◽  
Pure Hydrogen ◽  
Nox Emissions ◽  
Exhaust Gas ◽  
Gas Temperature ◽  
Lean Burn ◽  
Load Range ◽  
Excess Air

In the utilization of gas mixtures with high amounts of H2 there is a great number of applications of such special gases, for example several gases that result from pyrolysis or the gasification of biomass or thermally utilizable waste substances. What is special about gases containing H2 is the shifting of the lean-burn limit towards greater amounts of excess air than is the case with natural gas. This effect causes the mean combustion chamber temperatures to sink and the NOx emissions are reduced to a very low level. Depending on the amount of hydrogen and other gas components it is possible to attain NOx values of under 5 ppm. Also very interesting is the property of these H2-rich gas mixtures to have a neutral influence on the degree of efficiency (even with extremely high amounts of excess air). The background of this property lies in the considerably higher laminar flame speed of hydrogen. Especially in the lower and medium load range this effect can be utilized directly; in this regard it was possible to measure an efficiency of up to 2% points better with operation using pure hydrogen compared with NG. Higher BMEPs are also only possible to a limited extent with extreme lean-burn operation because the knocking limit is reached. Furthermore, the dimensioning of the turbocharger is becoming more and more difficult because the exhaust gas temperature upstream from the turbine sinks and as a result also the thermal energy is available only to a limited degree. When dealing with high amounts of H2, from the standpoint of operational reliability it is necessary to modify the mixture formation before the TC position to the pressure side position upstream from the intake valve, because otherwise load fluctuations could lead to undesired rich mixtures in the inlet side. As a result, backfiring could occur that could also cause engine damage and that could be hazardous for personnel. From the viewpoint of GE Jenbacher H2 technology can be applied relatively quickly to reduce NOx emissions. Especially when considering the “life cycle costs”, this potential solution is superior to concepts functioning on the basis of stoichiometric combustion. The next step that can be mentioned is the concept of fuel-reforming integrated in the engine — here a part of the exhaust gas energy is used to reform a relatively small amount of natural gas to a CH4/H2/CO mixture. With this concept, alongside the dramatic reduction of NOx emissions to the level of fuel cells, the degree of efficiency can be improved by about 2 to 3% points by means of “energy shifting”.

Experimental Investigation of a Heavy-Duty Compression-Ignition Engine Retrofitted to Natural Gas Spark-Ignition Operation

2019 ◽  
Vol 141 (11) ◽  
Author(s):  
Jinlong Liu ◽  
Hemanth Kumar Bommisetty ◽  
Cosmin Emil Dumitrescu
Keyword(s):  
Natural Gas ◽  
Spark Ignition ◽  
Operating Conditions ◽  
Compression Ignition ◽  
Heavy Duty ◽  
Compression Ignition Engine ◽  
Engine Operation ◽  
Cycle Variation ◽  
Spark Timing ◽  
Ci Engines

Heavy-duty compression-ignition (CI) engines converted to natural gas (NG) operation can reduce the dependence on petroleum-based fuels and curtail greenhouse gas emissions. Such an engine was converted to premixed NG spark-ignition (SI) operation through the addition of a gas injector in the intake manifold and of a spark plug in place of the diesel injector. Engine performance and combustion characteristics were investigated at several lean-burn operating conditions that changed fuel composition, spark timing, equivalence ratio, and engine speed. While the engine operation was stable, the reentrant bowl-in-piston (a characteristic of a CI engine) influenced the combustion event such as producing a significant late combustion, particularly for advanced spark timing. This was due to an important fraction of the fuel burning late in the squish region, which affected the end of combustion, the combustion duration, and the cycle-to-cycle variation. However, the lower cycle-to-cycle variation, stable combustion event, and the lack of knocking suggest a successful conversion of conventional diesel engines to NG SI operation using the approach described here.

Performance Prediction of Gas Turbine Under Different Strategies Using Low Heating Value Fuel

2013 ◽  
Author(s):  
Edson Batista da Silva ◽  
Marcelo Assato ◽  
Rosiane Cristina de Lima
Keyword(s):  
Natural Gas ◽  
Gas Turbine ◽  
Equivalence Ratio ◽  
Safe Operation ◽  
Engine Operation ◽  
Heating Value ◽  
Gasification Process ◽  
Surge Margin ◽  
And Performance ◽  
Industrial Gas Turbine

Usually, the turbogenerators are designed to fire a specific fuel, depending on the project of these engines may be allowed the operation with other kinds of fuel compositions. However, it is necessary a careful evaluation of the operational behavior and performance of them due to conversion, for example, from natural gas to different low heating value fuels. Thus, this work describes strategies used to simulate the performance of a single shaft industrial gas turbine designed to operate with natural gas when firing low heating value fuel, such as biomass fuel from gasification process or blast furnace gas (BFG). Air bled from the compressor and variable compressor geometry have been used as key strategies by this paper. Off-design performance simulations at a variety of ambient temperature conditions are described. It was observed the necessity for recovering the surge margin; both techniques showed good solutions to achieve the same level of safe operation in relation to the original engine. Finally, a flammability limit analysis in terms of the equivalence ratio was done. This analysis has the objective of verifying if the combustor will operate using the low heating value fuel. For the most engine operation cases investigated, the values were inside from minimum and maximum equivalence ratio range.

Turbine Blade Tip Clearance Measurement Instrumentation

2007 ◽  
Author(s):  
Eric B. Holmquist ◽  
Peter L. Jalbert
Keyword(s):  
Control System ◽  
Real Time ◽  
Tip Clearance ◽  
Engine Control ◽  
Operating Characteristics ◽  
Static Structure ◽  
Engine Operation ◽  
Area Of Interest ◽  
Blade Tip ◽  
Blade Tip Clearance

New and future gas turbine engines are being required to provide greater thrust with improved efficiency, while simultaneously reducing life cycle operating costs. Improved component capabilities enable active control methods to provide better control of engine operation with reduced margin. One area of interest is a means to assess the relative position of rotating machinery in real-time, in particular hot section turbo machinery. To this end, Hamilton Sundstrand is working to develop a real-time means to monitor blade position relative to the engine static structure. This approach may yield other engine operating characteristics useful in assessing component health, specifically measuring blade tip clearance, time-of-arrival, and other parameters. UTC is leveraging its many years of experience with engine control systems to develop a microwave-based sensing device, applicable to both military and commercial engines. The presentation will discuss a hot section engine demonstration of a blade position monitoring system and the control system implications posed by a microwave-based solution. Considerations necessary to implement such a system and the challenges associated with integrating a microwave-based sensor system into an engine control system are discussed.

Maintaining Low Exhaust Emissions With Turbocharged Gas Engines Using a Feedback Air–Fuel Ratio Control System

1987 ◽  
Vol 109 (4) ◽  
pp. 487-490 ◽  
Author(s):  
D. W. Eckard ◽  
J. V. Serve´
Keyword(s):  
Control System ◽  
Temperature Control ◽  
Exhaust Emissions ◽  
Ambient Conditions ◽  
Load Range ◽  
Heating Value ◽  
Gas Engine ◽  
Precise Control ◽  
Natural Gas Engine ◽  
Fuel Ratio

Maintaining low exhaust emissions on a turbocharged, natural gas engine through the speed and load range requires precise control of the air–fuel ratio. Changes in ambient conditions or fuel heating value will cause the air–fuel ratio to change substantially. By combining air–gas pressure with preturbine temperature control, the air–fuel ratio can be maintained regardless of changes in the ambient conditions or the fuel’s heating value. Design conditions and operating results are presented for an air–fuel controller for a turbocharged engine.

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