Effects of Humidity and Ambient Temperature on Engine Performance of Lean Burn Natural Gas Engines

2006 ◽  
Author(s):  
Andreas Wimmer ◽  
Eduard Schnessl
Keyword(s):  
Natural Gas ◽  
Fuel Consumption ◽  
Engine Performance ◽  
Optimal Operation ◽  
Nox Emission ◽  
Engine Fuel ◽  
Ambient Conditions ◽  
Lean Burn ◽  
Combustion Duration ◽  
Burn Rate

High demands are placed on large gas engines in the areas of performance, fuel consumption and emissions. In order to meet all these demands, it is necessary to operate the engine in its optimal range. At high engine loads the optimal operation range becomes narrower as the engine comes closer to the knocking or to the misfire limit. The ambient conditions are of increasing importance in this range of operation. Variations in humidity influence the engine’s burn rate characteristics. An increase in humidity reduces the burn rate and increases the combustion duration. This increase in combustion duration has the same effect as retarding the time of ignition. Thus the thermal efficiency is reduced. Additionally, the engine is more likely to misfire as humidity increases. The cylinder temperature affects the engine fuel efficiency, knocking, exhaust gas temperature and particularly NOx emission. An increase in manifold air temperature results in higher NOx emission, heat transfer and knocking tendency. To avoid knocking, the time of ignition must be retarded resulting in lower engine efficiency. In this paper the effects of changes in humidity and temperature of the intake air on engine performance were examined in a lean burn pre-chamber natural gas engine. Tests on a single cylinder research engine were carried out. Effects on knocking and misfire limit, NOx emissions and fuel consumption were investigated depending on engine load. The interpretation of the results was supported by an extended analysis of losses.

Engine Capability Prediction for SI Engine Fueled With Syngas

2015 ◽  
Author(s):  
Hui Xu ◽  
Leon A. LaPointe
Keyword(s):  
Natural Gas ◽  
Solid Waste ◽  
Laminar Flame ◽  
Combustion Engine ◽  
Flame Temperature ◽  
Engine Performance ◽  
Nox Emissions ◽  
Lean Burn ◽  
Gaseous Fuels ◽  
Combustion Duration

There are increasing interests in converting solid waste or lignocellulosic biomass into gaseous fuels and using reciprocating internal combustion engine to generate electricity. A widely used technique is gasification. Gasification is a process where the solid fuel and air are introduced to a partial oxidation environment, and generate combustible gaseous called synthesis gas or syngas. Converting solid waste into gaseous fuel can reduce landfill and create income for process owners. However it can be very challenging to use syngas on a gaseous fueled spark ignited engine, such as a natural gas (NG) engine. NG engines are typically developed with pipeline quality natural gas (PQNG). NG engines can operate at lean burn spark ignited (LBSI), or stoichiometric with EGR spark ignited (SESI) conditions. This work discusses the LBSI engine condition. NG engines can perform very differently when fueled with nonstandard gaseous fuels such as syngas without appropriate tuning. It is necessary to evaluate engine performance in terms of combustion duration, relative knock propensity and NOx emissions for such applications. Due to constraints in time and resources it is often not feasible to test such fuel blends in the laboratory. An analytical method is needed to predict engine performance in a timely manner. This study investigated the possibility of using syngas on a spark ignited engine developed with PQNG. Engine performance was predicted using in house developed models and PQNG as the reference fuel. Laminar flame speed (LFS), adiabatic flame temperature (AFT) and Autoignition interval (AI) are used to predict combustion duration, engine out NOx and engine knock propensity relative to NG at the target Lambda values. Single cylinder research engine data obtained under lean burn conditions fueled with PQNG was selected as the baseline. LFS, AFT and AI of syngas were computed at reference conditions. Lambda of operation was predicted for syngas to provide the same burn rate as NG at the reference Lambda value for NG. Analysis shows that, using syngas at the selected Lambda, the engine can have less engine out NOx emissions and less knock propensity relative to NG at the same speed and load. Modifications to fuel system components may be required to avoid engine derate.

Performance and Combustion Investigation of a Lean Burn Natural Gas Engine Using CFD

2018 ◽  
Author(s):  
Sridhar Sahoo ◽  
Srinibas Tripathy ◽  
Dhananjay Kumar Srivastava
Keyword(s):  
Natural Gas ◽  
Equivalence Ratio ◽  
Spark Ignition Engine ◽  
Engine Fuel ◽  
Lean Burn ◽  
Gas Engine ◽  
Natural Gas Engine ◽  
Spark Timing ◽  
Combustion Duration ◽  
Wide Range

Natural gas is widely used in sequentially port fuel injection engine to meet stringent emission regulation. Lean burn operation is one of the ways to improve spark-ignition engine fuel economy. The instability in the combustion process of the lean burn engine is one of the major challenges for engine research. In this study, the performance and combustion characteristics of a lean burn sequential injection compressed natural gas (CNG) engine were investigated numerically using computational fluid dynamics (CFD) modeling over a wide range of air/fuel equivalence ratio. A detailed chemical kinetic mechanism was used for natural gas combustion along with laminar flame speed model to capture lean burn operating condition within the combustion chamber. Combustion pressure, indicated mean effective pressure (IMEP), and heat release were analyzed for performance analysis, whereas flame development angle (CA 10), combustion duration, thermal efficiency were taken for combustion analysis. The results show that on increasing air/fuel equivalence ratio at a given spark timing, IMEP decreases as the lean burn mixture produces less amount of gross power output due to insufficient available energy. Moreover, lower burning velocity characteristic of natural gas extends the combustion duration, where a substantial amount of total energy released after top dead center. It is also seen that optimum spark timing (MBT) for maximum IMEP advances with an increase in air/fuel equivalence ratio due to late ignition timing under lean burn condition. CFD model successfully captures the effect of dilution to illustrate the considerations to design future combustion engine for spark ignited natural gas engine.

Engine Capability Prediction for Spark Ignited Engine Fueled With Syngas

2016 ◽  
Vol 138 (10) ◽  
Author(s):  
Hui Xu ◽  
Leon A. LaPointe
Keyword(s):  
Natural Gas ◽  
Solid Waste ◽  
Combustion Engine ◽  
Flame Temperature ◽  
Engine Performance ◽  
Nox Emissions ◽  
Si Engine ◽  
Lean Burn ◽  
Gaseous Fuels ◽  
Combustion Duration

Abstract There are increasing interests in converting solid waste or lignocellulosic biomass into gaseous fuels and using reciprocating internal combustion engine to generate electricity. A widely used technique is gasification. Gasification is a process where the solid fuel and air are introduced to a partial oxidation environment, and generate combustible gaseous called synthesis gas or syngas. Converting solid waste into gaseous fuel can reduce landfill and create income for process owners. However, it can be very challenging to use syngas on a gaseous fueled spark ignited (SI) engine, such as a natural gas (NG) engine. NG engines are typically developed with pipeline quality natural gas (PQNG). NG engines can operate at lean burn spark ignited (LBSI), or stoichiometric with exhaust gas recirculation (EGR) spark ignited (SESI) conditions. This work discusses the LBSI engine condition. NG engines can perform very differently when fueled with nonstandard gaseous fuels such as syngas without appropriate tuning. It is necessary to evaluate engine performance in terms of combustion duration, relative knock propensity, and NOx emissions for such applications. Due to constraints in time and resources it is often not feasible to test such fuel blends in the laboratory. An analytical method is needed to predict engine performance in a timely manner. This study investigated the possibility of using syngas on an SI engine developed with PQNG. Engine performance was predicted using in house developed models and PQNG as the reference fuel. Laminar flame speed (LFS), adiabatic flame temperature (AFT), and auto-ignition interval (AI) are used to predict combustion duration, engine out NOx and engine knock propensity relative to NG at the target lambda values. Single cylinder research engine data obtained under lean burn conditions fueled with PQNG was selected as the baseline. LFS, AFT, and AI of syngas were computed at reference conditions. Lambda of operation was predicted for syngas to provide the same burn rate as NG at the reference lambda value for NG. Analysis shows that, using syngas at the selected lambda, the engine can have less engine out NOx emissions and less knock propensity relative to NG at the same speed and load. Modifications to fuel system components may be required to avoid engine derate.

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.

scholarly journals Control-oriented analysis of a lean-burn light-duty natural gas research engine with scavenged pre-chamber ignition

2019 ◽  
Vol 176 (1) ◽  
pp. 42-53
Author(s):  
Severin HÄNGGI ◽  
Thomas HILFIKER ◽  
Patrik SOLTIC ◽  
Richard HUTTER ◽  
Christopher ONDER
Keyword(s):  
Natural Gas ◽  
Control Structure ◽  
Engine Performance ◽  
Combustion Stability ◽  
Performance Criteria ◽  
Transport Sector ◽  
Lean Burn ◽  
Fuel Ratio ◽  
Cng Engine ◽  
Lean Conditions

Natural gas is well-suited as a fuel in the transport sector. Due to its excellent combustion characteristics, engines operating with compressed natural gas (CNG) reach high efficiency, especially if operated at lean conditions. However, CNG engine research mainly focusses on stoichiometric conditions in order to use a three-way catalytic converter for the exhaust gas after treatment system. With the objective to explore the potential of CNG engines operated at lean conditions, a turbo-charged CNG engine with high com-pression ratio is developed and optimized for lean operation. In order to increase the ignition energy, the CNG engine is equipped with scavenged pre-chambers. A specific control structure is developed, which allows to operate the engine at a pre-defined (lean) air-to-fuel ratio. Further functionalities such as the combustion placement control and algorithms to estimate the conditions inside of the pre-chamber are implemented. The first part of this paper describes this engine control structure, which is specifically developed for the lean-burn CNG engine. In the second part, the effects of pre-chamber scavenging on engine performance criteria such as the combustion stability, engine efficiency or engine emissions are analyzed. With the objective to use pre-chamber scavenging to improve engine performance, a scavenging feed-back control strategy is proposed. In order to control the ignition delay, this strategy adapts the amount of CNG injected into the pre-chamber with a linear controller or an extremum seeking algorithm depending on the air-to-fuel ratio of the main chamber.

Inherent Fuel Consumption and Exhaust Emission of the CNG–Petrol Bi–Fuel Engine Based at Non–Loaded Operation

2012 ◽  
Author(s):  
Rahmat Mohsin ◽  
Zulkefli Yaacob ◽  
Zulkifli Abdul Majid ◽  
Shameed Ashraf
Keyword(s):  
Natural Gas ◽  
Fuel Consumption ◽  
Experimental Approach ◽  
Exhaust Emission ◽  
Engine Fuel ◽  
Fuel System ◽  
Compressed Natural Gas ◽  
Fuel Ratio ◽  
Carbon Dioxide Co2 ◽  
Natural Gas Vehicle

Gas asli termampat (CNG) merupakan bahan api alternatif yang paling berjaya dan digunakan dengan meluas bagi kenderaan terkini yang berada di pasaran. Kenderaan pacuan petrol bagi tujuan ini biasanya dilengkapkan dengan kit penukar gas asli bagi membolehkan operasian dwi-bahan api di antara CNG dan petrol. Pendekatan secara uji kaji ini difokuskan ke atas penggunaan bahan api, emisi ekzos dan kos bahan api di antara operasian gas asli dan petrol. Rig ujian terdiri dari sebuah sistem enjin teksi dwi-bahan api menggunakan 1500 cc dengan 12 injap sistem karburetor adalah dibina khusus. Penggunaan bahan api dan emisi ekzos yang setara diperolehi pada kelajuan putaran seminit (rpm) enjin yang berbeza ketika operasian menggunakan bahan api CNG dan petrol secara berasingan. Pengoperasian rpm enjin tanpa bebanan diubahsuai dari kedudukan pegun kepada kedudukan melebihi 5000 rpm untuk memperolehi profil penggunaan bahan api dan emisi ekzos. Kedua-dua data yang diperolehi ini kemudiannya digunakan bagi mengira kadar udara bahan api enjin. Kesemua ketiga-tiga parameter yang diperolehi digunakan untuk membuat perbandingan terhadap operasian gas asli dan petrol. Pemerhatian yang dibuat menunjukkan kadar udara bahan api bermula dari 19 ke 16.3 bagi operasian petrol dan dari 40 ke 18.7 untuk operasian menggunakan gas asli. Emisi ketika operasian menggunakan CNG jelas menunjukkan penurunan ketara ke atas keluaran hidrokarbon (HC), karbon monoksida (CO), karbon dioksida (CO2) dan nitrogen oksida (NOx) dibandingkan dengan operasian menggunakan petrol. Dari segi kos, penggunaan CNG memberikan keuntungan melebihi 50% terhadap kesemua kelajuan rpm enjin jika dibandingkan dengan operasian menggunakan petrol. Kata kunci: NGV, enjin dwi–bahan api, pengunaan bahan api, emisi ekzos, CNG, gas asli Compressed natural gas (CNG) is the most successful and widely used alternative fuel for vehicles in the market today. Petrol fuelled vehicles are fitted with natural gas vehicle (NGV) conversion kit to enable bi-fuel operation between CNG and petrol. This experimental approach is focused on the fuel consumption, exhaust emission and fuel cost between natural gas and petrol operations. The specially constructed test rig comprises of the bi-fuel fuel system employed in the 1500 cc 12 valves carburettor engine NGV taxis. The inherent fuel consumption and corresponding exhaust emission are acquired at different engine revolution per minute (rpm) during petrol and CNG operation separately. The engine rpm operating without load is varied from idle to more than 5000 rpm to acquire the fuel consumption and exhaust emission profile. These two acquired data are then used to calculate the engine’s air fuel ratio. All three parameters acquired are used to conduct comparisons between petrol and natural gas operation. It is seen that the bi-fuel system operates with air fuel ratio ranging from 19 to 16.3 for petrol operation and ranges from 40 to 18.7 for natural gas operations. The emission during CNG operation clearly shows significant decrease in hydrocarbon (HC), carbon monoxide (CO), carbon dioxide (CO2) and nitrogen oxide (NOx) over the use of petrol. In terms of cost, the use of CNG provides savings exceeding 50% through all engine rpm compared to petrol non-loaded operations. Key words: NGV, bi–fuel engine, fuel consumption, exhaust emission, CNG, natural gas

Optimal Operation of a Multi Source Multi Delivery Natural Gas Transmission Pipeline Network

2018 ◽  
Vol 13 (3) ◽  
Author(s):  
Dr. Adarsh Kumar Arya ◽  
Dr. Shrihari Honwad
Keyword(s):  
Natural Gas ◽  
Fuel Consumption ◽  
Optimal Operation ◽  
Gas Pipeline ◽  
Ant Colony ◽  
Generalized Gradient ◽  
Pipeline Network ◽  
Natural Gas Pipeline ◽  
Natural Gas Transmission ◽  
Transmission Pipeline

Abstract Transportation of natural gas from gathering station to consumption centers is done through complex gas pipeline network system. The huge cost involved in transporting natural gas has made pipeline optimization of increased interest in natural gas pipeline industries. In the present work a lesser known application of Ant Colony in pipeline optimization, has been implemented in a real gas pipeline network. The objective chosen is to minimize the fuel consumption in a gas pipeline network consisting of seven compressors. Pressures at forty-five nodes are chosen as the decision variables. Results of Ant Colony Optimization (ACO) have been compared with those of GAMS that utilizes ‘Generalized gradient principles’ for optimization. Our results utilizing ACO show significant improvement in fuel consumption reductions. Similar procedures can be adopted by researchers and pipeline managers to help pipeline operators in fixing up the pressures at different nodes so as the fuel consumption in compressors gets minimized.

Performance Characterization of Alternative Ignition Systems Using Optical Tools in Natural Gas Engines

2018 ◽  
Author(s):  
Bipin Bihari ◽  
Munidhar S. Biruduganti ◽  
Roberto Torelli ◽  
Dan Singleton
Keyword(s):  
Natural Gas ◽  
Engine Performance ◽  
Lean Burn ◽  
Natural Gas Engines ◽  
Reciprocating Engine ◽  
Optical Tools ◽  
Discharge Ignition ◽  
Performance And Emissions ◽  
Engine Performance And Emissions

Lean-burn combustion dominates the current reciprocating engine R&D efforts due to its inherent benefits of high BTE and low emissions. The ever-increasing push for high power densities necessitates high boost pressures. Therefore, the reliability and durability of ignition systems face greater challenges. In this study, four ignition systems, namely, stock Capacitive discharge ignition (CDI), Laser ignition, Flame jet ignition (FJI), and Nano-pulse delivery (NPD) ignition were tested using a single cylinder natural gas engine. Engine performance and emissions characteristics are presented highlighting the benefits and limitations of respective ignition systems. Optical tools enabled delving into the ignition delay period and assisted with some characterization of the spark and its impact on subsequent processes. It is evident that advanced ignition systems such as Lasers, Flame-jets and Nano-pulse delivery enable extension of the lean ignition limits of fuel/air mixtures compared to base CDI system.

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