Evaluation of Spark Plug and Timing Configurations on the Fuel Consumption, Combustion Stability, and Emissions of a Large-Bore, Two-Stroke, Natural Gas Engine

2016 ◽  
Author(s):  
Derek Johnson ◽  
Marc Besch ◽  
Nathaniel Fowler ◽  
Robert Heltzel ◽  
April Covington
Keyword(s):  
Natural Gas ◽  
Fuel Consumption ◽  
Combustion Engine ◽  
Engine Performance ◽  
Combustion Stability ◽  
Oxides Of Nitrogen ◽  
Natural Gas Engines ◽  
Fuel Delivery ◽  
Spark Plug ◽  
Trade Offs

Emissions compliance is a driving factor for internal combustion engine research pertaining to both new and old technologies. New standards and compliance requirements for off-road spark ignited engines are currently under review and include greenhouse gases. To continue operation of legacy natural gas engines, research is required to increase or maintain engine efficiency, while reducing emissions of carbon monoxide, oxides of nitrogen, and volatile organic compounds such as formaldehyde. A variety of technologies can be found on legacy, large-bore natural gas engines that allow them to meet current emissions standards — these include exhaust after-treatment, advanced ignition technologies, and fuel delivery methods. The natural gas industry uses a variety of spark plugs and tuning methods to improve engine performance or decrease emissions of existing engines. The focus of this study was to examine the effects of various spark plug configurations along with spark timing to examine any potential benefits. Spark plugs with varied electrode diameter, number of ground electrodes, and heat ranges were evaluated against efficiency and exhaust emissions. Combustion analyses were also conducted to examine peak firing pressure, location of peak firing pressure, and indicated mean effective pressure. The test platform was an AJAX-E42 engine. The engine has a bore and stroke of 0.216 × 0.254 meters (m), respectively. The engine displacement was 9.29 liters (L) with a compression ratio of 6:1. The engine was modified to include electronic spark plug timing capabilities along with a mass flow controller to ensure accurate fuel delivery. Each spark plug configuration was examined at ignition timings of 17, 14, 11, 8, and 5 crank angle degrees before top dead center. The various configurations were examined to identify optimal conditions for each plug comparing trade-offs among brake specific fuel consumption, oxides of nitrogen, methane, formaldehyde, and combustion stability.

Evaluation of a Lean-Burn Natural Gas Engine Operating on Variable Methane Number Fuel

2011 ◽  
Author(s):  
Cory J. Kreutzer ◽  
Daniel B. Olsen ◽  
Robin J. Bremmer
Keyword(s):  
Natural Gas ◽  
High Efficiency ◽  
Engine Performance ◽  
Combustion Stability ◽  
Lean Burn ◽  
Natural Gas Engines ◽  
Spark Timing ◽  
Gas Compression ◽  
Fuel Blending ◽  
Methane Number

Wellhead gas from which pipeline natural gas originates has significant variability in composition due to natural variations in deposits. Gas quality is influenced by relative concentrations of both inert and hydrocarbon species. Gas compression engines utilizing wellhead gas as a fuel source often require significant installation time and adjustment of stock configuration due to fuel compositions that vary with time and location. Lean burn natural gas engines are chosen as wellhead compression engines for high efficiency and low emissions while minimizing the effect of variable gas composition. Ideal engine conditions are maintained by operating within the knock and misfire limits of the engine. Additional data is needed to find engine operational limitations. In this work, experimental data was collected on a Cummins GTA8.3SLB engine operating on variable methane number fuel under closed-loop equivalence ratio control. A fuel blending system was used to vary methane number to simulate wellhead compositions. NOx and CO emissions were found to increase with decreasing methane number while combustion stability remained constant. In addition, the effects of carbon dioxide and nitrogen diluents in the fuel were investigated. When diluents were present in the fuel, engine performance could be maintained by spark timing advance.

On Comparative Engine Performance Testing With Fiber Delivered Laser Ignition and Electrical Ignition

2012 ◽  
Author(s):  
Nick Wilvert ◽  
Sachin Joshi ◽  
Azer Yalin
Keyword(s):  
Beam Quality ◽  
Engine Performance ◽  
Performance Testing ◽  
Laser Ignition ◽  
Solid Core ◽  
Oxides Of Nitrogen ◽  
Successful Operation ◽  
Natural Gas Engines ◽  
Nanosecond Pulses ◽  
Spark Plug

Laser ignition of natural gas engines has shown potential to improve many facets of engine performance including brake thermal efficiency, exhaust emissions, and durability as compared with traditional spark ignition. We present proof of concept of a novel fiber optic delivery approach using solid core multimode step index silica fibers with large cladding diameters (400 m core, 720 m cladding). The fibers were able to deliver high beam quality 25 nanosecond pulses of 1064 nm light with 7–10 mJ energy; sufficient to consistently ignite the engine at various air-fuel ratios and loads. Comparative tests between the laser spark plug and a traditional J-gap spark plug were performed on a single cylinder Waukesha Cooperative Fuel Research (CFR) engine running on bottled methane. Performance was measured in terms of the Coefficient of Variation (COV) of Net Mean Effective Pressure (NMEP), fuel specific efficiency, and emissions of oxides of nitrogen (NOx), carbon monoxide (CO), and total hydrocarbons (THC). Tests were run at three different NMEPs of 6, 8, and 12 bar at various air-fuel ratios. Results indicate successful operation of the fiber and improved engine performance at high NMEP and lean conditions.

Ignition in Pilot-Ignited Natural Gas Low Temperature Combustion: Multi-Zone Modeling and Experimental Results

2009 ◽  
Author(s):  
Sundar Rajan Krishnan ◽  
Kalyan Kumar Srinivasan ◽  
Kenneth Clark Midkiff
Keyword(s):  
Natural Gas ◽  
Shell Model ◽  
Ignition Delay ◽  
Combustion Engine ◽  
Engine Performance ◽  
Intake Manifold ◽  
Model Parameters ◽  
Injection Timing ◽  
Oxides Of Nitrogen ◽  
Gas Combustion

In previous research conducted by the authors, the Advanced Low Pilot-Ignited Natural Gas (ALPING) combustion employing early injection of small (pilot) diesel sprays to ignite premixed natural gas-air mixtures was demonstrated to yield very low oxides of nitrogen (NOx) emissions and fuel conversion efficiencies comparable to conventional diesel and dual fuel engines. In addition, it was observed that ignition of the diesel-air mixture in ALPING combustion had a profound influence on the ensuing natural gas combustion, engine performance and emissions. This paper discusses experimental and predicted ignition behavior for ALPING combustion in a single-cylinder engine at a medium load (BMEP = 6 bar), engine speed of 1700 rpm, and intake manifold temperature (Tin) of 75°C. Two ignition models were used to simulate diesel ignition under ALPING conditions: (a) Arrhenius-type ignition models, and (b) the Shell autoignition model. To the authors’ knowledge, the Shell model has previously not been implemented in a multi-zone phenomenological combustion simulation to simulate diesel ignition. The effects of pilot injection timing and Tin on ignition processes were analyzed from measured and predicted ignition delay trends. Experimental ignition delays showed a nonlinear trend (increasing from 11 to 51.5 degrees) in the 20°–60° BTDC injection timing range. Arrhenius-type ignition models were found to be inadequate and only yielded linear trends over the injection timing range. Even the inclusion of an equivalence ratio term in Arrhenius-type models did not render them satisfactory for the purpose of modeling ALPING ignition. The Shell model, on the other hand, predicted ignition better over the entire range of injection timings compared to the Arrhenius-type ignition delay models and also captured ignition delay trends at Tin = 95°C and Tin = 105°C. Parametric studies of the Shell model showed that the parameter Ap3, which affects chain propagation reactions, was important under medium load ALPING conditions. With all other model parameters remaining at their original values and only Ap3 modified to 8 × 1011 (from its original value of 1 × 1013), the Shell model predictions closely matched experimental ignition delay trends at different injection timings and Tin.

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.

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.

Precombustion Chamber Design and Performance Studies for a Large Bore Natural Gas Engine

2005 ◽  
Author(s):  
Daniel B. Olsen ◽  
Jessica L. Adair ◽  
Bryan D. Willson
Keyword(s):  
Natural Gas ◽  
Performance Studies ◽  
Engine Performance ◽  
Precombustion Chamber ◽  
Natural Gas Engines ◽  
Natural Gas Engine ◽  
Fuel Flow ◽  
Spark Plug ◽  
Lean Limit ◽  
And Performance

Precombustion chamber (PCC) ignition is a common method for extending the lean limit and reducing combustion variability in large bore (36–56 cm) natural gas engines. An important component that commonly fails and requires regular replacement, besides the spark plug, is the checkvalve. The checkvalve meters fuel flow into the PCC. In this program the use of an electronic valve for monitoring fuel to the PCC instead of the checkvalve is investigated. Metering the fuel into the PCC with an electronic valve provides a number of different options for improving performance in addition to the benefit of extended valve life. PCC nozzle design is also evaluated as a means for improving PCC and engine performance. Additionally, emissions formation in the PCC is evaluated through the use of a separate pressure transducer in the PCC and a fast sample valve that extracts gas from the PCC.

Effects of Natural Gas Compositions on Engine In-Cylinder Process

2015 ◽  
Vol 1092-1093 ◽  
pp. 498-503
Author(s):  
La Xiang ◽  
Yu Ding
Keyword(s):  
Natural Gas ◽  
Alternative Fuels ◽  
Combustion Process ◽  
Engine Performance ◽  
Maximum Temperature ◽  
Maximum Pressure ◽  
Test Bed ◽  
Promising Alternative ◽  
Natural Gas Engines ◽  
Lower Maximum

Natural gas (NG) is one of the most promising alternative fuels of diesel and petrol because of its economics and environmental protection. Generally the NG engine share the similar structure profile with diesel or petrol engine but the combustion characteristics of NG is varied from the fuels, so the investigation of NG engine combustion process receive more attentions from the researchers. In this paper, a zero-dimensional model on the basis of Vibe function is built in the MATLAB/SIMULINK environment. The model provides the prediction of combustion process in natural gas engines, which has been verified by the experimental data in the NG test bed. Furthermore, the influence of NG composition on engine performance is investigated, in which the in-cylinder maximum pressure and temperature and mean indicated pressure are compared using different type NG. It is shown in the results that NG with higher composition of methane results in lower maximum temperature and mean indicated pressure as well as higher maximum pressure.

The WLTC vs NEDC: A Case Study on the Impacts of Driving Cycle on Engine Performance and Fuel Consumption

2021 ◽  
Vol 18 (3) ◽  
pp. 9071-9081
Author(s):  
Jakub Lasocki
Keyword(s):  
Fuel Consumption ◽  
Combustion Engine ◽  
Engine Performance ◽  
Driving Cycle ◽  
Performance Characteristics ◽  
Pollutant Emission ◽  
Strong Impact ◽  
Light Duty ◽  
Light Duty Vehicles

The World-wide harmonised Light-duty Test Cycle (WLTC) was developed internationally for the determination of pollutant emission and fuel consumption from combustion engines of light-duty vehicles. It replaced the New European Driving Cycle (NEDC) used in the European Union (EU) for type-approval testing purposes. This paper presents an extensive comparison of the WLTC and NEDC. The main specifications of both driving cycles are provided, and their advantages and limitations are analysed. The WLTC, compared to the NEDC, is more dynamic, covers a broader spectrum of engine working states and is more realistic in simulating typical real-world driving conditions. The expected impact of the WLTC on vehicle engine performance characteristics is discussed. It is further illustrated by a case study on two light-duty vehicles tested in the WLTC and NEDC. Findings from the investigation demonstrated that the driving cycle has a strong impact on the performance characteristics of the vehicle combustion engine. For the vehicles tested, the average engine speed, engine torque and fuel flow rate measured over the WLTC are higher than those measured over the NEDC. The opposite trend is observed in terms of fuel economy (expressed in l/100 km); the first vehicle achieved a 9% reduction, while the second – a 3% increase when switching from NEDC to WLTC. Several factors potentially contributing to this discrepancy have been pointed out. The implementation of the WLTC in the EU will force vehicle manufacturers to optimise engine control strategy according to the operating range of the new driving cycle.

Ignition System Designed to Extend the Plug Life, and the Lean Limit in a Natural Gas Engine

2003 ◽  
Author(s):  
A. K. Chan ◽  
S. H. Waters
Keyword(s):  
Natural Gas ◽  
Engine Performance ◽  
Ignition System ◽  
Gas Engine ◽  
Natural Gas Engine ◽  
Dc System ◽  
Spark Plug ◽  
Long Duration ◽  
Discharge Duration ◽  
Lean Limit

An ignition system that is based on the alternating (AC) rather than the traditional direct (DC) current in the spark plug discharge has been developed at the Caterpillar Technical Center. This system can generate a long duration discharge with controllable power. It is believed that such an ignition system can provide both a leaner operating limit and a longer spark plug life than a traditional DC system due to the long discharge duration and the low discharge power. The AC ignition system has successfully been tested on a Caterpillar single cylinder G3500 natural gas engine to determine the effects on the engine performance, combustion characteristics and emissions. The test results indicate that while the AC ignition system has only a small impact on engine performance (with respect to a traditional DC system), it does extend the lean limit with lower NOx emissions. Evidences also show the potential of reduce spark plug electrode erosions from the low breakdown and sustaining discharge powers from the AC ignition system. This paper summarizes the prototype design and engine demonstration results of the AC ignition system.

scholarly journals Temperature parameters in the combustion chambers of CUMMINS KTA-50 engines operating on various fuels under different fuel consumption rates

2021 ◽  
Vol 315 ◽  
pp. 03011
Author(s):  
Georgiy Dubov ◽  
Alexander Bogomolov ◽  
Sergey Azikhanov ◽  
Pavel Strelnikov ◽  
Sergey Nokhrin
Keyword(s):  
Natural Gas ◽  
Fuel Consumption ◽  
Combustion Engine ◽  
Energy Charge ◽  
Motor Fuel ◽  
Liquefied Natural Gas ◽  
Open Pit ◽  
Mining Equipment ◽  
Evaporator Temperature ◽  
Dump Trucks

The issue of a comparative study of fuel consumption and temperature characteristics of gas-diesel BelAZ 75131 mining dump trucks equipped with an on-board cryogenic fuel system and hauling rock mass at the Kuzbass open-pit coal mine is considered in the article. A brief analysis of the efficiency of using liquefied natural gas (LNG) - methane - as a motor fuel for mining dump trucks is carried out. It is noted that the use of LNG fuel for heavy-duty dump trucks is one of the most promising ways to improve the environmental and economic performance during the operation of this type of mining equipment. The technique and instrumental base for conducting research are presented. The relationship between natural ratios of diesel fuel replacement with natural gas and the energy charge of these replacement is studied. The following data are presented: data on the consumption of vaporous (gaseous superheated) natural gas (hereinafter gaseous natural gas) during field operation of gas-diesel BelAZ 75131 mining dump trucks; flow rate of gaseous natural gas in pipelines; consumption of antifreeze at the inlet to the liquefied natural gas evaporator, as well as antifreeze temperature at the inlet and outlet of the evaporator; temperature of gaseous natural gas at the outlet of the reducer after the evaporator; data on the comparison of temperature profiles in the cylinders of CUMMINS KTA 50 internal combustion engine under diesel and gas-diesel operation.

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