Comparison of NOx emissions from hydrous ethanol and n-butanol predicted by an Otto cycle two-zone model using the Zeldovich reactions mechanism

2018 ◽  
Author(s):  
Jean L. S. Fagundez ◽  
Mario E. S. Martins ◽  
Nina P. G. Salau
Keyword(s):  
Zone Model ◽  
Nox Emissions ◽  
Otto Cycle ◽  
Hydrous Ethanol ◽  
Reactions Mechanism

scholarly journals A Study on the Performance of Combustion in a HCCI Engine Using n-Heptane by a Multi-Zone Model

2009 ◽  
Author(s):  
Hongsheng Guo ◽  
Hailin Li ◽  
W. Stuart Neill
Keyword(s):  
Numerical Simulation ◽  
Numerical Simulations ◽  
Chemical Species ◽  
Numerical Data ◽  
Operating Conditions ◽  
Zone Model ◽  
Nox Emissions ◽  
Hcci Engine ◽  
Operation Conditions ◽  
Wide Range

A study of n-heptane combustion in an HCCI engine was carried out by a multi-zone numerical simulation that covers a complete engine cycle. A reaction mechanism that includes 177 chemical species and 1638 reactions was used. The results of the numerical simulations were compared to existing experimental data for a range of air/fuel ratios, compression ratios and engine speeds. It is shown that the numerical simulation is able to reasonably capture the experimental cylinder pressure data over a wide range of operation conditions. It also provides a qualitative trend of CO emissions. The numerical simulation overpredicted the combustion at some operating conditions, such as at extremely high air/fuel ratios and higher engine speeds. Some differences were observed between the experimental and numerical data for NOX emissions. The numerical simulation predicted a monotonic decrease in NOX emissions as air/fuel ratio increased or compression ratio decreased, while an increase in NOX emissions was observed experimentally when combustion became very weak at extremely high air/fuel ratios or low compression ratios. It is suggested that further experiments and numerical simulations should be performed to explain this discrepancy.

Efficacy of Add-On Hydrous Ethanol Dual Fuel Systems to Reduce NOx Emissions From Diesel Engines

2016 ◽  
Author(s):  
Jeffrey T. Hwang ◽  
Alex J. Nord ◽  
William F. Northrop
Keyword(s):  
Diesel Engines ◽  
Fuel Injection ◽  
Dual Fuel ◽  
Nox Emissions ◽  
Energy Fraction ◽  
No Formation ◽  
Peak Cylinder Pressure ◽  
Zone Modeling ◽  
Diesel Fuel Injection ◽  
Hydrous Ethanol

Aftermarket dual-fuel injection systems using a variety of different fumigants have been proposed as alternatives to expensive after-treatment to control NOX emissions from legacy diesel engines. However, our previous work has shown that available add-on systems using hydrous ethanol as the fumigant achieve only minor benefits in emissions without recalibration of the diesel fuel injection strategy. This study experimentally re-evaluates a novel aftermarket dual-fuel port fuel injection (PFI) system used in our previous work, with the addition of higher flow injectors to increase the fumigant energy fraction (FEF), defined as the ratio of energy provided by the hydrous ethanol on a lower heating value (LHV) basis to overall fuel energy. Results of this study confirm our earlier findings that as FEF increases, NO emissions decrease, while NO2 and unburned ethanol emissions increase, leading to no change in overall NOX. Peak cylinder pressure and apparent rates of heat release are not strongly dependent on FEF, indicating that in-cylinder NO formation rates by the Zel’dovich mechanism remains the same. Through single zone modeling, we show the feasibility of in-cylinder NO conversion to NO2 aided by unburned ethanol. The modeling results indicate that NO to NO2 conversion occurs during the early expansion stroke where bulk gases have temperature in the range of 1150–1250 K. This work conclusively proves that aftermarket dual fuel systems for fixed calibration diesel engines cannot reduce NOX emissions without lowering peak temperature during diffusive combustion responsible for forming NO in the first place.

Efficacy of Add-On Hydrous Ethanol Dual Fuel Systems to Reduce NOx Emissions From Diesel Engines

2017 ◽  
Vol 139 (4) ◽  
Author(s):  
Jeffrey T. Hwang ◽  
Alex J. Nord ◽  
William F. Northrop
Keyword(s):  
Diesel Engines ◽  
Fuel Injection ◽  
Dual Fuel ◽  
Nox Emissions ◽  
Energy Fraction ◽  
No Formation ◽  
Peak Cylinder Pressure ◽  
Zone Modeling ◽  
Diesel Fuel Injection ◽  
Hydrous Ethanol

Aftermarket dual-fuel injection systems using a variety of different fumigants have been proposed as alternatives to expensive after-treatment to control NOx emissions from legacy diesel engines. However, our previous work has shown that available add-on systems using hydrous ethanol as the fumigant achieve only minor benefits in emissions without recalibration of the diesel fuel injection strategy. This study experimentally re-evaluates a novel aftermarket dual-fuel port fuel injection (PFI) system used in our previous work, with the addition of higher flow injectors to increase the fumigant energy fraction (FEF), defined as the ratio of energy provided by the hydrous ethanol on a lower heating value (LHV) basis to overall fuel energy. Results of this study confirm our earlier findings that as FEF increases, NO emissions decrease, while NO2 and unburned ethanol emissions increase, leading to no change in overall NOx. Peak cylinder pressure and apparent rates of heat release are not strongly dependent on FEF, indicating that in-cylinder NO formation rates by the Zel'dovich mechanism remain the same. Through single zone modeling, we show the feasibility of in-cylinder NO conversion to NO2 aided by unburned ethanol. The modeling results indicate that NO to NO2 conversion occurs during the early expansion stroke where bulk gases have temperature in the range of 1150–1250 K. This work conclusively proves that aftermarket dual fuel systems for fixed calibration diesel engines cannot reduce NOx emissions without lowering peak temperature during diffusive combustion responsible for forming NO in the first place.

Exploring Strategies for Reducing High Intake Temperature Requirements and Allowing Optimal Operational Conditions in a Biogas Fueled HCCI Engine for Power Generation

2012 ◽  
Vol 134 (7) ◽  
Author(s):  
Iván D. Bedoya ◽  
Samveg Saxena ◽  
Francisco J. Cadavid ◽  
Robert W. Dibble
Keyword(s):  
Power Generation ◽  
Power Output ◽  
Numerical Results ◽  
Inlet Temperature ◽  
Zone Model ◽  
Nox Emissions ◽  
Efficient Operation ◽  
Operational Conditions ◽  
Hcci Engines ◽  
Temperature Requirements

This paper evaluates strategies for reducing the intake temperature requirement for igniting biogas in homogeneous charge compression ignition (HCCI) engines. The HCCI combustion is a promising technology for stationary power generation using renewable fuels in combustion engines. Combustion of biogas in HCCI engines allows high thermal efficiency similar to diesel engines, with low net CO2 and low NOx emissions. However, in order to ensure the occurrence of autoignition in purely biogas fueled HCCI engines, a high inlet temperature is needed. This paper presents experimental and numerical results. First, the experimental analysis on a 4 cylinder, 1.9 L Volkswagen TDI diesel engine running with biogas in the HCCI mode shows high gross indicated mean effective pressure (close to 8 bar), high gross indicated efficiency (close to 45%) and NOx emissions below the 2010 US limit (0.27 g/kWh). Stable HCCI operation is experimentally demonstrated with a biogas composition of 60% CH4 and 40% CO2 on a volumetric basis, inlet pressures of 2–2.2 bar (absolute), and inlet temperatures of 200–210 °C for equivalence ratios between 0.19–0.29. At lower equivalence ratios, slight changes in the inlet pressure and temperature caused large changes in cycle-to-cycle variations, while at higher equivalence ratios these same small pressure and temperature variations caused large changes to the ringing intensity. Second, numerical simulations have been carried out to evaluate the effectiveness of high boost pressures and high compression ratios for reducing the inlet temperature requirements while attaining safe operation and high power output. The one zone model in Chemkin was used to evaluate the ignition timing and peak cylinder pressures with variations in temperatures at intake valve close (IVC) from 373 to 473 K. In-cylinder temperature profiles between IVC and ignition were computed using Fluent 6.3 and fed into the multizone model in Chemkin to study combustion parameters. According to the numerical results, the use of both higher boost pressures and higher compression ratios permit lower inlet temperatures within the safe limits experimentally observed and allow higher power output. However, the range of inlet temperatures allowing safe and efficient operation using these strategies is very narrow, and precise inlet temperature control is needed to ensure the best results.

Hydrous Ethanol Steam Reforming and Thermochemical Recuperation to Improve Dual-Fuel Diesel Engine Emissions and Efficiency

2018 ◽  
Author(s):  
Jeffrey T. Hwang ◽  
Seamus P. Kane ◽  
William F. Northrop
Keyword(s):  
Diesel Engine ◽  
Steam Reforming ◽  
Diesel Fuel ◽  
Dual Fuel ◽  
Ethanol Steam Reforming ◽  
Nox Emissions ◽  
Heating Value ◽  
Secondary Fuel ◽  
Hydrous Ethanol ◽  
Ethanol Steam

Dual-fuel strategies can enable replacement of diesel fuel with low reactivity biofuels like hydrous ethanol. Our previous work has shown that dual-fuel strategies using port injection of hydrous ethanol can replace up to 60% of diesel fuel on an energy basis. However, they yield negligible benefits in NOx emissions, soot emissions, and brake thermal efficiency (BTE) over conventional single fuel diesel operation. Pretreatment of hydrous ethanol through steam reforming before mixing with intake air offers the potential to both increase BTE and decrease soot and NOx emissions. Steam reforming can upgrade the heating value of the secondary fuel through thermochemical recuperation (TCR) and produces inert gases to act as a diluent similar to exhaust gas recirculation. This study experimentally investigated a novel thermally integrated steam reforming reactor that uses sensible and chemical energy in the exhaust to provide the necessary heat for hydrous ethanol steam reforming. An off-highway diesel engine was operated at three speed and load settings with varying hydrous ethanol flow rates reaching fumigant energy fractions of up to 70%. The engine achieved soot reductions of close to 90% and minor NOx reductions; however, carbon monoxide and unburned hydrocarbon emissions increased. A first law energy balance using the experimental data shows that efficient TCR effectively upgraded the heating value of the secondary fuel. Overall, hydrous ethanol steam reforming using TCR can lead to 23% increase in fuel heating value at 100% conversion, a limit approached in the conducted experiments.

Effect of operation under lean conditions on NOx emissions and fuel consumption fueling an SI engine with hydrous ethanol–gasoline blends enhanced with synthesis gas

Energy ◽  
2021 ◽  
pp. 121694
Author(s):  
Ahmed A. Al-Harbi ◽  
Abdullah J. Alabduly ◽  
Abdullah M. Alkhedhair ◽  
Naif B. Alqahtani ◽  
Miqad S. Albishi
Keyword(s):  
Fuel Consumption ◽  
Synthesis Gas ◽  
Nox Emissions ◽  
Si Engine ◽  
Hydrous Ethanol ◽  
Lean Conditions

Prediction of NOx emissions for high speed DI Diesel engines using a semi-empirical, two-zone model

2017 ◽  
Vol 153 ◽  
pp. 659-670 ◽  
Author(s):  
Stelios A. Provataris ◽  
Nicholas S. Savva ◽  
Theofanis D. Chountalas ◽  
Dimitrios T. Hountalas
Keyword(s):  
Diesel Engines ◽  
High Speed ◽  
Zone Model ◽  
Nox Emissions ◽  
Semi Empirical

Hydrous Ethanol Steam Reforming and Thermochemical Recuperation to Improve Dual-Fuel Diesel Engine Emissions and Efficiency

2019 ◽  
Vol 141 (11) ◽  
Author(s):  
Jeffrey T. Hwang ◽  
Seamus P. Kane ◽  
William F. Northrop
Keyword(s):  
Diesel Engine ◽  
Steam Reforming ◽  
Diesel Fuel ◽  
Dual Fuel ◽  
Ethanol Steam Reforming ◽  
Nox Emissions ◽  
Heating Value ◽  
Secondary Fuel ◽  
Hydrous Ethanol ◽  
Ethanol Steam

Dual-fuel strategies can enable replacement of diesel fuel with low reactivity biofuels like hydrous ethanol. Previous work has shown that dual-fuel strategies using port injection of hydrous ethanol can replace up to 60% of diesel fuel on an energy basis. However, they yield negligible benefits in NOX emissions, soot emissions, and brake thermal efficiency (BTE) over conventional single fuel diesel operation. Pretreatment of hydrous ethanol through steam reforming before mixing with intake air offers the potential to both increase BTE and decrease soot and NOX emissions. Steam reforming can upgrade the heating value of the secondary fuel through thermochemical recuperation (TCR) and produces inert gases to act as a diluent similar to exhaust gas recirculation. This study experimentally investigated a novel thermally integrated steam reforming TCR reactor that uses sensible and chemical energy in the exhaust to provide the necessary heat for hydrous ethanol steam reforming. An off-highway diesel engine was operated at three speed and load settings with varying hydrous ethanol flow rates reaching fumigant energy fractions of up to 70%. The engine achieved soot reductions of close to 90% and minor NOX reductions; however, carbon monoxide and unburned hydrocarbon emissions increased. A first law energy balance using the experimental data shows that the developed TCR system effectively upgraded the heating value of the secondary fuel. Overall, hydrous ethanol steam reforming using TCR can lead to 23% increase in fuel heating value at 100% conversion, a limit approached in the conducted experiments.

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