Experience With Gas Engines Optimized for H2-Rich Fuels

2003 ◽  
Author(s):  
G. R. Herdin ◽  
F. Gruber ◽  
D. Plohberger ◽  
M. Wagner
Keyword(s):  
Natural Gas ◽  
Fuel Efficiency ◽  
Electrical Power ◽  
Nox Emissions ◽  
Engine Emissions ◽  
Lean Burn ◽  
Good Efficiency ◽  
Gas Engine ◽  
Natural Gas Engines ◽  
Fuel Technology

The gas engine is a very efficient possibility of a technological approach for the conversion of chemically bound energy into mechanical or electrical power. Degrees of efficiency achieved thus far through the electrification of natural gas amount to up to 45% depending on the engine size and further potentials are already being opened up. Gas engines therefore do not need to fear a comparison with diesel engines in terms of efficiency. The modern gas engines have considerable advantages regarding emissions. The state of the art for the NOx emissions of natural gas engines can presently be given as 0.7 g/kWh (diesel 5 g NOx/kWh) with practically particle-free combustion. As a result of these features the gas engine is especially suitable for the very efficient process of cogeneration of heat and power, through which total degrees of fuel efficiency of about 90% can be attained. As such, the gas engine is even superior to all previously introduced types of fuel cells. The utilization of H2-rich gases as fuel can be seen as a new field of application of gas engines. Jenbacher AG already has many years of experience in the field of “H2-rich fuels” with optimization of combustion control and mixture formation. The H2 content extend from 100% to very low caloric values of gases in the range of 1.67 MJ/Nm3. The gases to be utilized by the gas engines come primarily from thermal pyrolysis processes of biomass or RDF fuels. A very good efficiency behavior with uncommonly low NOx emissions can be determined as the common result of all gas engine sizes. In the case of the high NH3 content of e.g. wood gas, despite the extreme lean-burn operation through the primary formation of NOx from the fuel, no NOx minimum can be attained. For the future, making the step into H2-rich fuel technology particularly regarding emissions means a big step towards the low NOx concepts and thus the further reduction of engine emissions.

Experimental study of combustion strategy for jet ignition on a natural gas engine

2020 ◽  
pp. 146808742097775
Author(s):  
Ziqing Zhao ◽  
Zhi Wang ◽  
Yunliang Qi ◽  
Kaiyuan Cai ◽  
Fubai Li
Keyword(s):  
Experimental Study ◽  
Natural Gas ◽  
Efficient Points ◽  
Lean Burn ◽  
Gas Engine ◽  
Absolute Value ◽  
Natural Gas Engines ◽  
Natural Gas Engine ◽  
Excess Air ◽  
Lean Limit

To explore a suitable combustion strategy for natural gas engines using jet ignition, lean burn with air dilution, stoichiometric burn with EGR dilution and lean burn with EGR dilution were investigated in a single-cylinder natural gas engine, and the performances of two kinds of jet ignition technology, passive jet ignition (PJI) and active jet ignition (AJI), were compared. In the study of lean burn with air dilution strategy, the results showed that AJI could extend the lean limit of excess air ratio (λ) to 2.1, which was significantly higher than PJI’s 1.6. In addition, the highest indicated thermal efficiency (ITE) of AJI was shown 2% (in absolute value) more than that of PJI. Although a decrease of NOx emission was observed with increasing λ in the air dilution strategy, THC and CO emissions increased. Stoichiometric burn with EGR was proved to be less effective, which can only be applied in a limited operation range and had less flexibility. However, in contrast to the strategy of stoichiometric burn with EGR, the strategy of lean burn with EGR showed a much better applicability, and the highest ITE could achieve 45%, which was even higher than that of lean burn with air dilution. Compared with the most efficient points of lean burn with pure air dilution, the lean burn with EGR dilution could reduce 78% THC under IMEP = 1.2 MPa and 12% CO under IMEP = 0.4 MPa. From an overall view of the combustion and emission performances under both low and high loads, the optimum λ would be from 1.4 to 1.6 for the strategy of lean burn with EGR dilution.

A Reduced Chemical Kinetic Mechanism for CFD Simulations of High BMEP, Lean-Burn Natural Gas Engines

2012 ◽  
Author(s):  
David Martinez-Morett ◽  
Luigi Tozzi ◽  
Anthony J. Marchese
Keyword(s):  
High Pressure ◽  
Natural Gas ◽  
Chemical Kinetic ◽  
Cfd Simulations ◽  
Lean Burn ◽  
Gas Engine ◽  
Natural Gas Engines ◽  
Natural Gas Engine ◽  
Kinetic Mechanisms ◽  
Lean Conditions

Recent developments in numerical techniques and computational processing power now permit time-dependent, multi-dimensional computational fluid dynamic (CFD) calculations with reduced chemical kinetic mechanisms (approx. 20 species and 100 reactions). Such computations have the potential to be highly effective tools for designing lean-burn, high BMEP natural gas engines that achieve high fuel efficiency and low emissions. Specifically, these CFD simulations can provide the analytical tools required to design highly optimized natural gas engine components such as pistons, intake ports, precombustion chambers, fuel systems and ignition systems. To accurately model the transient, multi-dimensional chemically reacting flows present in these systems, chemical kinetic mechanisms are needed that accurately reproduce measured combustion data at high pressures and lean conditions, but are of sufficient size to enable reasonable computational times. Presently these CFD models cannot be used as accurate design tools for application in high BMEP lean-burn gas engines because existing detailed and reduced mechanisms fail to accurately reproduce experimental flame speed and ignition delay data for natural gas at high pressure (40 atm and higher) and lean (0.6 equivalence ratio (ϕ) and lower) conditions. Existing methane oxidation mechanisms have typically been validated with experimental conditions at atmospheric and intermediate pressures (1 to 20 atm) and relatively rich stoichiometry. These kinetic mechanisms are not adequate for CFD simulation of natural gas combustion in which elevated pressures and very lean conditions are typical. This paper provides an analysis, based on experimental data, of the laminar flame speed computed from numerous, detailed chemical kinetic mechanisms for methane combustion at pressures and equivalence ratios necessary for accurate high BMEP, lean-burn natural gas engine modeling. A reduced mechanism that was shown previously to best match data at moderately lean and high pressure conditions was updated for the conditions of interest by performing sensitivity analysis using CHEMKIN. The reaction rate constants from the most sensitive reactions were appropriately adjusted in order to obtain a better agreement at high pressure lean conditions. An evaluation of this adjusted mechanism, “MD19”, was performed using Converge CFD software. The results were compared to engine data and a remarkable improvement on combustion performance prediction was obtained with the MD19 mechanism.

Effects of Spark Advance Angle on Combustion and Emission Characteristics of a Compressed Natural Gas Engine

2011 ◽  
Vol 383-390 ◽  
pp. 6085-6090
Author(s):  
Xiao Na Sun ◽  
Hong Guang Zhang ◽  
Xin Wang ◽  
Dao Jing Wang ◽  
Guo Yong Zheng ◽  
...  
Keyword(s):  
Natural Gas ◽  
Pressure Rise ◽  
Emission Characteristics ◽  
Nox Emissions ◽  
Lean Burn ◽  
Compressed Natural Gas ◽  
Gas Engine ◽  
Natural Gas Engine ◽  
Peak Cylinder Pressure ◽  
Co Emission

The effects of spark advance angle on combustion and emission characteristics of a compressed natural gas engine have been investigated experimentally in this paper. The experimental data was conducted under various excessive air coefficient conditions using an electronic ignition system developed self-dependently. The results show that the peak cylinder pressure and peak rate of pressure rise ascends with the increase of spark advance angle in a certain extent, and their corresponding location are advanced. The CO emission keeps almost the same as the spark advance angle varies in the overall mode range. The HC and NOx emissions ascend with the increase of spark advance angle under the condition that excessive air coefficient is near the theoretical value. Under the lean-burn condition, the HC and NOx emissions are almost the same while the spark advance angle varies.

Modeling NOx Emissions from Lean-Burn Natural Gas Engines

1998 ◽  
Author(s):  
Lee G. Dodge ◽  
John T. Kubesh ◽  
David W. Naegeli ◽  
Patrick F. Campbell
Keyword(s):  
Natural Gas ◽  
Nox Emissions ◽  
Lean Burn ◽  
Natural Gas Engines

Analysis of the Rotating Arc Spark Plug in a Natural Gas Engine

2005 ◽  
Author(s):  
Jim Tassitano ◽  
James E. Parks
Keyword(s):  
Natural Gas ◽  
Fuel Efficiency ◽  
Cost Effective ◽  
Combustion Stability ◽  
Engine Operation ◽  
Gas Engine ◽  
Natural Gas Engines ◽  
Natural Gas Engine ◽  
Spark Plug ◽  
Rotating Arc

Large natural gas engines are durable and cost-effective generators of power for distributed energy applications. Fuel efficiency is an important aspect of distributed generation since operating costs associated with fuel consumption are the major component of energy cost on a life-cycle basis; furthermore, higher fuel efficiency results in lower CO2 emissions. Leaner operation of natural gas engines can result in improved fuel efficiency; however, engine operation becomes challenging at leaner air-to-fuel ratios due to several factors. One factor in combustion control is ignition. At lean air-fuel mixtures, reliable and repeatable ignition is necessary to maintain consistent power production from the engine, and spark plug quality and durability play an important role in reliability of ignition. Here research of a novel spark plug design for lean natural gas engines is presented. The spark plug is an annular gap spark plug with a permanent magnet that produces a magnetic field that forces the spark to rotate during spark discharge. The rotating arc spark plug (RASP) has the potential to improve ignition system reliability and durability. In the study presented here, the RASP plug was operated in a small natural gas engine, and combustion stability (measured by the coefficient of variation of indicated mean effective pressure (IMEP)) was measured as a function of air-to-fuel ratio to characterize the ignition performance at lean mixtures. Comparisons were made to a standard J-plug spark plug.

Survey of Gas Engine Performance and Future Trends

2003 ◽  
Author(s):  
Timothy J. Callahan
Keyword(s):  
Power Generation ◽  
Natural Gas ◽  
High Efficiency ◽  
Engine Performance ◽  
Exhaust Emission ◽  
Nox Emissions ◽  
Gas Engine ◽  
Natural Gas Engines ◽  
Reciprocating Engines ◽  
Performance And Emissions

Worldwide, reciprocating engines play a major role in power generation. Many of the reciprocating engines are diesel engines used as stand-by generators, but increasingly, natural gas engines are providing distributed base load generation and finding service in combined heat and power applications. The economics of power generation continues to place a premium on engine efficiency while environmental regulators continue to legislate lower and lower exhaust emission levels, specifically NOx emissions. NOx emissions and efficiency tend to be proportional, so while not mutually exclusive, low NOx and high efficiency are difficult to obtain simultaneously. In spite of the NOx-efficiency relationship, natural gas engines are more efficient with lower emissions today than in the past and the trend toward higher efficiency will continue in the future. This paper surveys current natural gas engine performance and emissions and projects future engine performance. This paper also introduces the ARES and ARICE programs for developing revolutionary technology for high efficiency and low emissions.

A Turbocharged Lean-Burn 4.3 Liter Natural Gas Engine

1995 ◽  
Author(s):  
Dan D. Giordano ◽  
Peter W. Petersen
Keyword(s):  
Natural Gas ◽  
Lean Burn ◽  
Gas Engine ◽  
Natural Gas Engine

Numerical Simulations of Mixture Formation in Combustion Chambers of Lean-Burn Natural Gas Engines Incorporating a Sub-Chamber

2017 ◽  
Author(s):  
Yuzuru Nada ◽  
So Morimoto ◽  
Yoshiyuki Kidoguchi ◽  
Ryu Kaya ◽  
Hideaki Nakano ◽  
...  
Keyword(s):  
Natural Gas ◽  
Numerical Simulations ◽  
Combustion Chambers ◽  
Mixture Formation ◽  
Lean Burn ◽  
Natural Gas Engines
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