Combustion Characteristics of Lean Burn and Stoichiometric With Exhaust Gas Recirculation Spark-Ignited Natural Gas Engines

2015 ◽  
Vol 137 (11) ◽  
Author(s):  
Hui Xu ◽  
Leon A. LaPointe
Keyword(s):  
Natural Gas ◽  
Output Power ◽  
Flame Temperature ◽  
Exhaust Gas Recirculation ◽  
Exhaust Gas ◽  
Lean Burn ◽  
Brake Mean Effective Pressure ◽  
Combustion Duration ◽  
Combustion Properties ◽  
Gas Recirculation

Natural gas (NG) has been widely used in reciprocating engines for various applications such as automobile, electricity generation, and gas compression. It is in the public interest to burn fuels more efficiently and at lower exhaust emissions. NG is very suitable to serve this purpose due to its clean combustion, small carbon footprint, and, with recent breakthroughs in drilling technologies, increased availability and low cost. NG can be used in lean burn spark-ignited (LBSI) or stoichiometric EGR spark-ignited (SESI) engines. Selection of either LBSI or SESI requires accommodation of requirements such as power output/density, engine efficiency, emissions, knock margin, and cost. The work described in this paper investigated the feasibility of operating an engine originally built as an LBSI under SESI conditions. Analytical tools and workflow developed by Cummins, Inc., are used in this study. The tools require fundamental combustion properties as inputs, including laminar flame speed (LFS), adiabatic flame temperature (AFT), and auto-ignition interval (AI). These parameters provide critical information about combustion duration, engine out NOx, and relative knock propensity. An existing LBSI engine operating at its as released lambda was selected as baseline. The amount of exhaust gas recirculation (EGR) for the SESI configuration was selected so that it would have the same combustion duration as that of the LBSI at its reference lambda. One-dimensional (1D) cycle simulations were conducted under both SESI and LBSI conditions assuming constant output power, compression ratio, volumetric efficiency, heat release centroid, and brake mean effective pressure (BMEP). The 1D cycle simulations provide peak cylinder pressure (PCP) and peak unburned zone temperature (PUZT) under LBSI and SESI conditions. The results show that the SESI configuration has lower PCP but higher PUZT than that of the LBSI for the same output power. Also, for the same combustion duration, SESI has higher AFT than that of LBSI, resulting in higher engine out NOx emissions. The SESI configuration has shorter AI than that of LBSI engine, or smaller relative knock margin. Reduction of output power and emissions aftertreatment in the form of a three-way catalyst (TWC) is required to operate under SESI engine conditions.

Combustion Characteristics of Lean Burn and Stoichiometric With EGR Spark Ignited Natural Gas Engines

2014 ◽  
Author(s):  
Hui Xu ◽  
Leon A. LaPointe
Keyword(s):  
Natural Gas ◽  
Output Power ◽  
Laminar Flame ◽  
Low Cost ◽  
Flame Temperature ◽  
Lean Burn ◽  
Brake Mean Effective Pressure ◽  
Combustion Duration ◽  
Combustion Properties ◽  
Zone Temperature

Natural gas has been widely used in reciprocating engines for various applications such as automobile, electricity generation, and gas compression. It is in the public interest to burn fuels more efficiently and at lower exhaust emissions. Natural gas is very suitable to serve this purpose due to its clean combustion, small carbon footprint, and, with recent breakthroughs in drilling technologies, increased availability and low cost. Natural gas can be used in lean burn spark ignited (LBSI) or stoichiometric EGR spark ignited (SESI) engines. Selection of either LBSI or SESI requires accommodation of requirements such as power output/density, engine efficiency, emissions, knock margin, and cost. The work described in this paper investigated the feasibility of operating an engine originally built as an LBSI under SESI conditions. Analytical tools and workflow developed by Cummins, Inc. are used in this study. The tools require fundamental combustion properties as inputs, including laminar flame speed (LFS), adiabatic flame temperature (AFT) and autoignition interval (AI). These parameters provide critical information about combustion duration, engine out NOx, and relative knock propensity. An existing LBSI engine operating at its as released lambda was selected as baseline. The amount of EGR for the SESI configuration was selected so that it would have the same combustion duration as that of the LBSI at its reference lambda. One dimensional (1D) cycle simulations were conducted under both SESI and LBSI conditions assuming constant output power, compression ratio, volumetric efficiency, heat release centroid and brake mean effective pressure (BMEP). The 1D cycle simulations provide peak cylinder pressure (PCP) and peak unburned zone temperature (PUZT) under LBSI and SESI conditions. The results show that the SESI configuration has lower PCP but higher peak unburned zone temperature than that of the LBSI for the same output power. Also, for the same combustion duration, SESI has higher AFT than that of LBSI, resulting in higher engine out NOx emissions. The SESI configuration has shorter AI than that of LBSI engine, or smaller relative knock margin. Reduction of output power and emissions aftertreatment in the form of a three way catalyst (TWC) is required to operate under SESI engine conditions.

Evaluating dedicated exhaust gas recirculation on a stoichiometric industrial natural gas engine

2019 ◽  
pp. 146808741986473 ◽  
Author(s):  
Chris A Van Roekel ◽  
David T Montgomery ◽  
Jaswinder Singh ◽  
Daniel B Olsen
Keyword(s):  
Natural Gas ◽  
Power Density ◽  
Positive Impact ◽  
Exhaust Gas Recirculation ◽  
Exhaust Gas ◽  
Lean Burn ◽  
Gas Engine ◽  
Natural Gas Engine ◽  
Excess Air ◽  
Gas Recirculation

Due to the market presence that natural gas has and is expected to have in the future energy sector, research and development of novel natural gas combustion strategies to increase power density, lower total emissions, and increase overall efficiency is warranted. Dilution whether by excess air or by exhaust gas recirculation has historically been implemented on diesel, natural gas, and gasoline engines to mitigate various regulated emissions. In the large industrial natural gas engine industry, excess air dilution or ultra-lean-burn operation has afforded lean-burn engines increased power density and reduced NO x emissions. This advance in technology has allowed lean-burn engines to compete in markets such as electrical power generation which previously they had not been able. However, natural gas engines utilizing a non-selective catalytic reduction system or three-way catalyst must operate under stoichiometric conditions and thus are limited in power density by exhaust gas temperatures. In previous gasoline small engine research, a novel exhaust gas recirculation technique called dedicated exhaust gas recirculation was shown to have a positive impact on engine-out emissions of NO x and unburned hydrocarbons while also lowering exhaust component temperatures. This work seeks to understand the consequences of implementing a dedicated exhaust gas recirculation system on a multi-cylinder stoichiometric industrial natural gas engine. The results of this initial evaluation demonstrate reductions in engine-out NO x and CO emissions and improvements in engine-out exhaust gas temperatures with the dedicated exhaust gas recirculation technique. However, in a low-turbulence combustion chamber, dedicated exhaust gas recirculation significantly lowers the overall rate of combustion and results in significant differences in cylinder-to-cylinder combustion.

Evaluation of Emissions Characteristics of Marine Diesel Engine Intake of Exhaust Gas of Lean Burn Gas Engine

2017 ◽  
Vol 140 (2) ◽  
Author(s):  
Yoshifuru Nitta ◽  
Dong-Hoon Yoo ◽  
Sumito Nishio ◽  
Yasuhisa Ichikawa ◽  
Koichi Hirata ◽  
...  
Keyword(s):  
Diesel Engine ◽  
Natural Gas ◽  
Co2 Emissions ◽  
Exhaust Gas Recirculation ◽  
Marine Diesel Engine ◽  
Exhaust Gas ◽  
Lean Burn ◽  
Gas Engine ◽  
Marine Diesel ◽  
Gas Recirculation

The need for reductions of nitrogen oxides (NOx), sulfur oxides (SOx), and carbon dioxide (CO2) emissions has been acknowledged on the global level. However, it is difficult to meet the strengthened emissions regulations by using the conventional marine diesel engines. Therefore, lean burn gas engines have been recently attracting attention in the maritime industry. Because they use natural gas as fuel and can simultaneously reduce both NOx and CO2 emissions. On the other hand, since methane is the main component of natural gas, the slipped methane, which is the unburned methane emitted from the lean burn gas engines, might have a potential impact on global warming. The authors have proposed a combined exhaust gas recirculation (C-EGR) system to reduce the slipped methane from the gas engines and NOx from marine diesel engines by providing the exhaust gas from lean burn gas engine to the intake manifold of the marine diesel engine using a blower. Since the exhaust gas from the gas engine includes slipped methane, this system could reduce both the NOx from the marine diesel engine and the slipped methane from the lean burn gas engine simultaneously. This paper introduces the details of the proposed C-EGR system and presents the experimental results of emissions characteristics on the C-EGR system. As a result, it was confirmed that the C-EGR system attained more than 75% reduction of the slipped methane in the intake gas. Additionally, the NOx emission from the diesel engine decreased with the effect of the exhaust gas recirculation (EGR) system.

Addition of Exhaust Gas Recirculation Onto a Large-Bore, Two-Stroke Natural Gas Engine, and its Effects on Fuel Consumption, Emissions, and Combustion

2016 ◽  
Author(s):  
Derek Johnson ◽  
Marc Besch ◽  
Nathaniel Fowler ◽  
Robert Heltzel ◽  
April Covington
Keyword(s):  
Natural Gas ◽  
Fuel Efficiency ◽  
Thermal Inertia ◽  
Engine Performance ◽  
Exhaust Gas Recirculation ◽  
Exhaust Gas ◽  
Lean Burn ◽  
Spark Plug ◽  
Spark Timing ◽  
Gas Recirculation

The focus of this research was to examine the effects of adding exhaust gas recirculation (EGR) on a large bore 2-stroke, lean-burn natural gas (2SLB) engine in its stock configuration, using a previously determined optimal spark plug. EGR has been a common emissions reduction technology used for on-road gasoline, natural gas, and diesel fueled vehicles. EGR — both cooled and uncooled — is found in nearly all on-road and many off-road engines. The optimal spark plug was found in other research and it was tested with various rates of EGR. The test platform was a 1971 Cameron AJAX-E42 single-cylinder engine — common to the natural gas industry. The engine had a bore and stroke of 8.5 × 10 inches, respectively. The engine displacement was 567 cubic inches with a trapped 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 EGR configuration was examined at spark timings of 14, 11, and 8 CAD BTDC. Tests were conducted using an air-cooled, eddy-current power absorber at an engine speed of 525 RPM and load of 400 1b.-ft. of torque. Due to its large thermal inertia, the engine was operated for three hours prior to data collection to ensure representative and operation. In-cylinder pressure data were collected using a piezoelectric pressure transducer at increments of 0.25 CAD. Various levels of EGR and spark timing conditions were evaluated against engine performance including both regulated and unregulated exhaust emissions. Volumetric EGR rates of 2.5% showed reduced NOx emissions and improved fuel efficiency while rates of 5% did not yield NOx reductions.

Technical Note: Investigation on emission characteristics of a compression ignition engine with oxygenated fuels and exhaust gas recirculation

2000 ◽  
Vol 214 (5) ◽  
pp. 503-508 ◽  
Author(s):  
H. W. Wang ◽  
Z. H. Huang ◽  
L. B. Zhou ◽  
D. M. Jiang ◽  
Z. L. Yang
Keyword(s):  
Linear Relationship ◽  
Reduction Rate ◽  
Exhaust Gas Recirculation ◽  
Emission Characteristics ◽  
Exhaust Gas ◽  
Compression Ignition ◽  
Mass Percentage ◽  
Compression Ignition Engine ◽  
Brake Mean Effective Pressure ◽  
Gas Recirculation

Investigations of emission characteristics were carried out on a compression ignition, dimethyl ether engine (DME) with exhaust gas recirculation (EGR) and on a diesel engine with a dimethyl carbonate (DMC) additive. The experimental results show that the DME engine with EGR can simultaneously reduce smoke and NOx emissions. The NOx can be reduced by about 20 per cent for every 10 per cent of EGR introduction, while smoke remains at zero. The diesel equivalent brake specific fuel consumption (b.s.f.c.) shows a slight decrease when DMC is added, while the effective thermal efficiency shows a slight improvement. It is found that the smoke reduction rate and smoke show a linear relationship with DMC percentage or oxygen mass percentage in the diesel fuel. For the specific brake mean effective pressure (b.m.e.p.), smoke will be reduced by 20 per cent for every 10 per cent DMC added and by 40 per cent when the oxygen mass percentage in the fuel reaches 10 per cent. The CO decreases when DMC is added, while NOx shows an increase. This difference is pronounced at a high b.m.e.p. For the specific b.m.e.p., CO and NOx show a linear relationship with DMC mass percentage in the fuel; CO will be reduced by 20 per cent while NOx will be increased by 20 per cent for every 10 per cent DMC added.

Control-Oriented Physics-Based NOX Emission Model for a Diesel Engine With Exhaust Gas Recirculation

2020 ◽  
Vol 1 (1) ◽  
Author(s):  
Saravanan Duraiarasan ◽  
Rasoul Salehi ◽  
Anna Stefanopoulou ◽  
Siddharth Mahesh ◽  
Marc Allain
Keyword(s):  
Diesel Engine ◽  
Test Procedure ◽  
Flame Temperature ◽  
Exhaust Gas Recirculation ◽  
Nox Emission ◽  
Injection Timing ◽  
Exhaust Gas ◽  
Engine Control ◽  
Gas Recirculation ◽  
The Impact

Abstract Stringent NOX emission norm for heavy duty vehicles motivates the use of predictive models to reduce emissions of diesel engines by coordinating engine parameters and aftertreatment. In this paper, a physics-based control-oriented NOX model is presented to estimate the feedgas NOX for a diesel engine. This cycle-averaged NOX model is able to capture the impact of all major diesel engine control variables including the fuel injection timing, injection pressure, and injection rate, as well as the effect of cylinder charge dilution and intake pressure on the emissions. The impact of the cylinder charge dilution controlled by the engine exhaust gas recirculation (EGR) in the highly diluted diesel engine of this work is modeled using an adiabatic flame temperature predictor. The model structure is developed such that it can be embedded in an engine control unit without any need for an in-cylinder pressure sensor. In addition, details of this physics-based NOX model are presented along with a step-by-step model parameter identification procedure and experimental validation at both steady-state and transient conditions. Over a complete federal test procedure (FTP) cycle, on a cumulative basis the model prediction was more than 93% accurate.

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