The Performance and Emissions of a Conventional Natural Gas/Diesel Dual Fuel Engine at Various Operating Conditions

Author(s):  
Darko Kozarac ◽  
Mario Sremec ◽  
Mladen Bozic ◽  
Ante Vucetic
Author(s):  
Liu Shenghua ◽  
Zhou Longbao ◽  
Wang Ziyan ◽  
Ren Jiang

The combustion characteristics of a turbocharged natural gas and diesel dual-fuelled compression ignition (CI) engine are investigated. With the measured cylinder pressures of the engine operated on pure diesel and dual fuel, the ignition delay, effects of pilot diesel and engine load on combustion characteristics are analysed. Emissions of HC, CO, NOx and smoke are measured and studied too. The results show that the quantity of pilot diesel has important effects on the performance and emissions of a dual-fuel engine at low-load operating conditions. Ignition delay varies with the concentration of natural gas. Smoke is much lower for the developed dual-fuel engine under all the operating conditions.


Author(s):  
N. T. Shoemaker ◽  
C. M. Gibson ◽  
A. C. Polk ◽  
S. R. Krishnan ◽  
K. K. Srinivasan

Different combustion strategies and fuel sources are needed to deal with increasing fuel efficiency demands and emission restrictions. One possible strategy is dual fueling using readily available resources. Propane and natural gas are readily available with the current infrastructure and biodiesel is growing in popularity as a renewable fuel. This paper presents experimental results from dual fuel combustion of methane (as a surrogate for natural gas) and propane as primary fuels with biodiesel pilots in a 1.9 liter, turbocharged, 4-cylinder compression ignition engine at 1800 rev/min. Experiments were performed with different percentage energy substitutions (PES) of propane and methane and at different brake mean effective pressures (BMEP/bmep). Brake thermal efficiency (BTE) and emissions (NOx, HC, CO, CO2, O2 and smoke) were also measured. Maximum PES levels for B100-methane dual fueling were limited to 70% at 2.5 bars bmep and 48% at 10 bars bmep, and corresponding values for B100-propane dual fueling were 64% and 43%, respectively. Maximum PES was limited by misfire at 2.5 bars bmep and the onset of engine knock at 10 bars bmep. Dual fuel BTEs approached straight B100 values at 10 bars bmep while they were significantly lower than B100 values at 2.5 bars bmep. In general, dual fueling was beneficial in reducing NOx and smoke emissions by 33% and 50%, respectively, from baseline B100 levels; however, both CO and THC emissions were significantly higher than baseline B100 levels at all PES and loads.


Author(s):  
Liu Shenghua ◽  
Wang Ziyan ◽  
Ren Jiang

A natural gas and diesel dual-fuel turbocharged compression ignition (CI) engine is developed to reduce emissions of a heavy-duty diesel engine. The compressed natural gas (CNG) pressure regulator is specially designed to feed back the boost pressure to simplify the fuel metering system. The natural gas bypass improves the engine response to acceleration. The modes of diesel injection are set according to the engine operating conditions. The application of honeycomb mixers changes the flowrate shape of natural gas and reduces hydrocarbon (HC) emission under low-load and lowspeed conditions. The cylinder pressures of a CI engine fuelled with diesel and dual fuel are analysed. The introduction of natural gas makes the ignition delay change with engine load. Under the same operating conditions, the emissions of smoke and NOx from the dual-fuel engine are both reduced. The HC and CO emissions for the dual-fuel engine remain within the range of regulation.


Author(s):  
Marcus Grochowina ◽  
Michael Schiffner ◽  
Simon Tartsch ◽  
Thomas Sattelmayer

Dual-Fuel (DF) engines offer great fuel flexibility since they can either run on gaseous or liquid fuels. In the case of Diesel pilot ignited DF-engines the main source of energy is provided by gaseous fuel, whereas the Diesel fuel acts only as an ignition source. Therefore, a proper autoignition of the pilot fuel is of utmost importance for combustion in DF-engines. However, autoignition of the pilot fuel suffers from lower compression temperatures of Miller or Atkinson valve timings. These valve timings are applied to increase efficiency and lower nitrogen oxide engine emissions. In order to improve the ignition, it is necessary to understand which parameters influence the ignition in DF-engines. For this purpose, experiments were conducted and the influence of parameters such as injection pressure, pilot fuel quantity, compression temperature and air-fuel equivalence ratio of the homogenous natural gas-air mixture were investigated. The experiments were performed on a periodically chargeable combustion cell using optical high-speed recordings and thermodynamic measurement techniques for pressure and temperature. The study reveals that the quality of the Diesel pilot ignition in terms of short ignition delay and a high number of ignited sprays significantly depends on the injection parameters and operating conditions. In most cases, the pilot fuel suffers from too high dilution due to its small quantity and long ignition delays. This results in a small number of ignited sprays and consequently leads to longer combustion durations. Furthermore, the experiments confirm that the natural gas of the background mixture influences the autoignition of the Diesel pilot oil.


Author(s):  
Marcus Grochowina ◽  
Michael Schiffner ◽  
Simon Tartsch ◽  
Thomas Sattelmayer

Dual-fuel (DF) engines offer great fuel flexibility since they can either run on gaseous or liquid fuels. In the case of diesel pilot-ignited DF engines, the main source of energy is provided by gaseous fuel, whereas the diesel fuel acts only as an ignition source. Therefore, a proper auto-ignition of the pilot fuel is of utmost importance for combustion in DF engines. However, auto-ignition of the pilot fuel suffers from lower compression temperatures of Miller or Atkinson valve timings. These valve timings are applied to increase efficiency and lower nitrogen oxide (NOx) engine emissions. In order to improve the ignition, it is necessary to understand which parameters influence the ignition in DF engines. For this purpose, experiments were conducted and the influence of parameters, such as injection pressure, pilot fuel quantity, compression temperature, and air–fuel (A/F) equivalence ratio of the homogenous natural gas–air mixture were investigated. The experiments were performed on a periodically chargeable combustion cell using optical high-speed recordings and thermodynamic measurement techniques for pressure and temperature. The study reveals that the quality of the diesel pilot ignition in terms of short ignition delay and a high number of ignited sprays significantly depends on the injection parameters and operating conditions. In most cases, the pilot fuel suffers from too high dilution due to its small quantity and long ignition delays. This results in a small number of ignited sprays and consequently leads to longer combustion durations. Furthermore, the experiments confirm that the natural gas of the background mixture influences the auto-ignition of the diesel pilot oil.


Author(s):  
Andrew Hockett ◽  
Michael Flory ◽  
Joel Hiltner ◽  
Scott Fiveland

Natural gas/diesel dual fuel engines used in oil and gas drilling operations must be able to meet NOx emissions limits across a wide range of substitution percentage, which affects the air to natural gas ratio or gas lambda. In a dual fuel engine operating at high substitution, premixed, propagating natural gas flames occur and the NOx formed in such premixed flames is known to be a strong function of gas lambda. Consequently there is interest in understanding how NOx formation in a dual fuel engine is affected by gas lambda. However, NOx formation in a dual fuel engine is complicated by the interaction with the non-premixed diesel jet flame. As a result, previous studies have shown that enriching the air-fuel ratio can either increase or decrease NOx emissions depending on the operating conditions investigated. This study presents multi-dimensional combustion simulations of an air-fuel ratio sweep from gas lambda 2.0 to 1.5 at 80% substitution, which exhibited a minimum in NOx emissions at a natural gas lambda of 1.75. Images from the simulations are used to provide detailed explanations of the physical processes responsible for the minimum NOx trend with natural gas lambda.


Author(s):  
Federico Bonzani ◽  
Giacomo Pollarolo ◽  
Franco Rocca

ANSALDO ENERGIA S.p.A. has been commissioned by ELETTRA GLT S.p.A, a company located in Trieste, Italy for the realisation of a combined cycle plant where all the main components (gas turbine, steam turbine, generator and heat recovery steam generator) are provided by ANSALDO ENERGIA. The total power output of the plant is 180 MW. The gas turbine is a V94.2 K model gas turbine dual fuel (natural gas and steelworks process gas), where the fuel used as main fuel is composed by a mixture of natural gas, blast furnace gas and coke oven gas in variable proportions according to the different working conditions of the steel work plant. The main features adopted to burn such a kind of variability of fuels are reported below: • fuel as by product of steel making factory gas (coke oven gas “COG”, blast furnace gas “BFG”) with natural gas integration; • modified compressor from standard V94.2, since no air extraction is foreseen; • dual fuel burner realised based on Siemens design. This paper describes the operating experience achieved on the gas turbine, focusing on the main critical aspect to be overcome and on to the test results during the commissioning and the early operating phase. The successful performances carried out have been showing a high flexibility in burning with stable combustion a very different fuel compositions with low emissions measured all operating conditions.


Author(s):  
N. T. Shoemaker ◽  
C. M. Gibson ◽  
A. C. Polk ◽  
S. R. Krishnan ◽  
K. K. Srinivasan

Different combustion strategies and fuel sources are needed to deal with increasing fuel efficiency demands and emission restrictions. One possible strategy is dual fueling using readily available resources. Propane and natural gas are readily available with the current infrastructure and biodiesel is growing in popularity as a renewable fuel. This paper presents experimental results from dual fuel combustion of methane (as a surrogate for natural gas) and propane as primary fuels with biodiesel pilots in a 1.9 liter, turbocharged, 4 cylinder diesel engine at 1800 rev/min. Experiments were performed with different percentage energy substitutions (PES) of propane and methane and at different brake mean effective pressures (BMEP/bmep). Brake thermal efficiency (BTE) and emissions (NOx, HC, CO, CO2, O2 and smoke) were also measured. Maximum PES levels for B100-methane dual fuelling were limited to 70% at 2.5 bar bmep and 48% at 10 bar bmep, and corresponding values for B100-propane dual fuelling were 64% and 43%, respectively. Maximum PES was limited by misfire at 2.5 bar bmep and the onset of engine knock at 10 bar bmep. Dual fuel BTEs approached straight B100 values at 10 bar bmep while they were significantly lower than B100 values at 2.5 bar bmep. In general dual fuelling was beneficial in reducing NOx and smoke emissions by 33% and 50%, respectively from baseline B100 levels; however, both CO and THC emissions were significantly higher than baseline B100 levels at all PES and loads.


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