scholarly journals Two-Stroke Low Speed Diesel Engine Simulation Model for NOx Analysis

2017 ◽  
Vol 6 (1) ◽  
pp. 14-23
Author(s):  
Branko Lalić ◽  
Nikola Račić ◽  
Gojmir Radica
Keyword(s):  
Diesel Engine ◽  
Simulation Model ◽  
Flame Temperature ◽  
Combustion Process ◽  
Nox Emissions ◽  
Oxide Formation ◽  
Slow Speed ◽  
Engine Simulation ◽  
Excess Air ◽  
Marine Engines

All commercial marine engines have to comply with IMO regulations on emissions, especially of nitrogen oxides. This paper describes the gases produced in the combustion process in the diesel engine, and the manner of pollutant creation. Several models of slow-speed diesel engines have been developed and analysed. The characteristics of the simulation model are compared with the characteristics obtained on the testbed, and their differences considered. Using the term for the formation of NOx, as well as independently developed programs in MATLAB, the rate of nitrogen oxide formation was obtained as a function of excess air, pressure and temperature. The reduction of excess air increases adiabatic flame temperature and has an effect on NOx emissions. The obtained results are compared with the actual values measured on the testbed.

Experimental Study on the Combustion Process and Performance of Diesel Engines Fueled by Emulsion Diesel With Novel Organic Additives

2013 ◽  
Author(s):  
Wenming Yang ◽  
Hui An ◽  
Jing Li ◽  
Amin Maghbouli ◽  
Kian Jon Chua
Keyword(s):  
Diesel Engine ◽  
Diesel Engines ◽  
Thermal Efficiency ◽  
Gasoline Engine ◽  
Combustion Process ◽  
Nox Emissions ◽  
Organic Additives ◽  
Oil Droplets ◽  
And Performance ◽  
One Year

Transportation is one of the major contributors to the world’s energy consumption and greenhouse gases emissions. The need for increased efficiency has placed diesel engine in the spotlight due to its superior thermal efficiency and fuel economy over gasoline engine. However, diesel engines also face the major disadvantage of increased NOx emissions. To address this issue, three types of emulsion fuels with different water concentrations (5%, 10% and 15% mass water) are produced and tested. Novel organic materials (glycerin and ployethoxy-ester) are added in the fuel to provide extra oxygen for improving combustion. NP-15 is added as surfactant which can help to reduce the oil and water surface tension, activates their surface, and maximizes their superficial contact areas, thereby forming a continuous and finely dispersed droplets phase. The stability of the emulsion fuels is tested under various environmental temperature for one year, and no significant separation is observed. It is better than normal emulsion fuel which can only maintain the state for up to three months. The combustion process and performance of the emulsion fuels are tested in a four-stroke, four cylinder diesel engine. The results indicate that the water droplets enclosed in the emulsion fuel explode at high temperature environment and help to break up the big oil droplets into smaller ones, thereby significantly increase the surface area of the oil droplets and enhance the heat transfer from hot gas to the fuel. As a result, the fuel evaporation is improved and the combustion process is accelerated, leading to an improved brake thermal efficiency (up to 14.2%). Meanwhile, the presence of the water causes the peak temperature of the flame to drop, thereby significantly bringing down the NOx emissions by more than 30%.

Closed-Loop Combustion Control Using OH Radical Emissions

2000 ◽  
Author(s):  
Zhu (Julie) Meng ◽  
Robert J. Hoffa ◽  
Charles A. DeMilo ◽  
Todd T. Thamer
Keyword(s):  
Control System ◽  
Simulation Model ◽  
Gas Turbine ◽  
Closed Loop ◽  
System Simulation ◽  
Combustion Process ◽  
Operating Conditions ◽  
Nox Emissions ◽  
Oh Radical ◽  
Emissions Control

The combustion process in gas-turbine engines produces emissions, especially nitrogen oxides (NOx) and carbon monoxide (CO), which change dramatically with combustor operating conditions. As part of this study, the application of active feedback control technologies to reduce thermal NOx emissions is modeled numerically and demonstrated experimentally. A new optical flame sensor, designed by Ametek Power & Industrial Products, has been successfully implemented as the feedback element in a proof-of-concept control system used to minimize NOx emissions. The sensor consists of a robust mechanical package, as well as electronics suitable for severe gas-turbine environments. Results from system rig tests correlate closely to theoretical predictions, as described in literature and produced by a control system simulation model. The control system simulation model predicts the efficacy of controlling engine operating characteristics based on chemical luminescence of the OH radical. The model consists of a fuel pump and metering device, a fuel-air mixing scheme, a combustion model, the new ultraviolet (UV) feedback flame sensor, and a simple gain block. The input reference to the proportional emissions control is the fuel-to-air equivalence ratio, which is empirically correlated to the desired low level of NOx emissions while satisfying other operating conditions, such as CO emissions and power. Results from the closed-loop emissions control simulation and rig tests were analyzed to determine the capability of the UV flame sensor to measure and control the combustion process in a gas-turbine engine. The response characteristics, overshoot percentage, rise time, settling time, accuracy, resolution, and repeatability are addressed.

scholarly journals Analysis on Pattern of Heat Release Rate in Two-Stroke Slow Speed Diesel Engine (2nd Report: Prediction of the Combustion Process)

2003 ◽  
Vol 38 (5) ◽  
pp. 303-308
Author(s):  
Takeshi Imahashi ◽  
Eiji Tomita ◽  
Sadami Yoshiyama ◽  
Kouji Moriyama
Keyword(s):  
Diesel Engine ◽  
Heat Release ◽  
Heat Release Rate ◽  
Release Rate ◽  
Combustion Process ◽  
Slow Speed

Visualization of the Effects of Post Injection and Swirl on the Combustion Process of a Passenger Car Common Rail DI Diesel Engine

2003 ◽  
Author(s):  
Arjan Helmantel ◽  
Joop Somhorst ◽  
Ingemar Denbratt
Keyword(s):  
Diesel Engine ◽  
Combustion Chamber ◽  
Flame Temperature ◽  
Combustion Process ◽  
Small Diameter ◽  
Ccd Camera ◽  
Common Rail ◽  
Post Injection ◽  
Passenger Car ◽  
Di Diesel Engine

The effects of variations in injection strategy and swirl on a DI Diesel engine performance and emissions were tested. The cylinder head was fitted with a small diameter endoscope, coupled with a triggered CCD camera, in order to study the effect of these variations on the combustion process. The images that were taken of the combustion process were used to calculate the spatial and temporal distribution of flame temperature and soot kks factor by using the 2-color method. The engine used in the experiments is a single cylinder version of a modern, passenger car type, common rail Diesel engine with a displacement of 480 cc. The fitted endoscope caused very little interference with the combustion chamber due to its small dimensions. The 65 degree angle view of the endoscope allowed coverage of a large portion of the entire combustion chamber. The combustion images and derived temperatures and soot concentrations were used to study the influence of post injection and high swirl. Adding a third (post) injection to the pilot and main injection increases the mixing and the flame temperature during the second half of the combustion process, thereby improving soot oxidation. The fuel efficiency was not negatively affected by the later phasing of part of the heat release. Increased swirl of the intake air was also studied. An 80% increase in swirl-ratio was achieved by closing off one of the two intake ports with a butterfly valve. The improved mixing gave significant reductions in soot emissions, with a small increase in NOx formation.

Practical Issues of Combustion Oxygen Measurement Specifically Related to NOx Emissions

2004 ◽  
Author(s):  
Jim Scott ◽  
Bobby Dennis
Keyword(s):  
Power Plants ◽  
Practical Importance ◽  
Combustion Process ◽  
Nox Emissions ◽  
Regulatory Requirements ◽  
Excess Air ◽  
Oxygen Measurement ◽  
The Common ◽  
Common Problems ◽  
Oxygen Measurements

Power plants concerned with lowering NOx emissions are making tremendous changes to accommodate EPA regulatory requirements. A substantial number of these changes include the expansion and upgrade of the plant combustion oxygen measurement equipment. There is a striking relationship between the number of NOx reductions projects and the sales quantity of insitu oxygen detectors. The reason is that power plant betterment groups, operators, boiler manufacturers and engineering firms understand the direct relationship between NOx and excess air in the combustion process. An area of daily practical importance to boiler operators and I&C teams are the common problems with insitu oxygen measurements. This paper focuses on the practical issues of combustion oxygen measurement as they relate to specifically to fuel usage and NOx emissions.

scholarly journals Effects of Injection Rate Profile on Combustion Process and Emissions in a Diesel Engine

2017 ◽  
Vol 2017 ◽  
pp. 1-8 ◽  
Author(s):  
Fuqiang Bai ◽  
Zuowei Zhang ◽  
Yongchen Du ◽  
Fan Zhang ◽  
Zhijun Peng
Keyword(s):  
Diesel Engine ◽  
Heat Release ◽  
Combustion Process ◽  
Injection Rate ◽  
Injection System ◽  
Nox Emissions ◽  
Release Process ◽  
Common Rail Injection System ◽  
Soot Emissions ◽  
Rate Profile

When multi-injection is implemented in diesel engine via high pressure common rail injection system, changed interval between injection pulses can induce variation of injection rate profile for sequential injection pulse, though other control parameters are the same. Variations of injection rate shape which influence the air-fuel mixing and combustion process will be important for designing injection strategy. In this research, CFD numerical simulations using KIVA-3V were conducted for examining the effects of injection rate shape on diesel combustion and emissions. After the model was validated by experimental results, five different shapes (including rectangle, slope, triangle, trapezoid, and wedge) of injection rate profiles were investigated. Modeling results demonstrate that injection rate shape can have obvious influence on heat release process and heat release traces which cause different combustion process and emissions. It is observed that the baseline, rectangle (flat), shape of injection rate can have better balance between NOx and soot emissions than the other investigated shapes. As wedge shape brings about the lowest NOx emissions due to retarded heat release, it produces the highest soot emissions among the five shapes. Trapezoid shape has the lowest soot emissions, while its NOx is not the highest one. The highest NOx emissions were produced by triangle shape due to higher peak injection rate.

Some Studies on NOX Reduction From a Diesel Engine Using Stabilized Emulsion

2018 ◽  
Author(s):  
Naveen Kumar ◽  
Harveer Singh Pali ◽  
Sidharth Bansal
Keyword(s):  
Diesel Engine ◽  
Water Content ◽  
Volume Fraction ◽  
Nox Reduction ◽  
Flame Temperature ◽  
Water Volume ◽  
Nox Emissions ◽  
Oxides Of Nitrogen ◽  
Engine Operation ◽  
Water Emulsion

The twentieth century has seen a rapid twenty-fold increase in the use of fossil fuels. Personal and commercial transportation consumes 2% of the total world energy. The main products of combustion of fossil fuel are carbon mono oxide (CO), unburned hydrocarbons (HC), Carbon dioxide (CO2), oxides of sulfur (SOx), oxides of nitrogen (NOx) and particulate matter. Oxides of nitrogen (NOx) are the major diesel engine pollutants and referred to as mixtures of nitric oxide (NO) and nitrogen dioxide (NO2). NOx emissions are required to be controlled because NO and NO2 contribute to the formation of smog, an environmental and human health hazard. NO2 is also directly of concern as a human lung aggravation. To reduce NOx emissions from a diesel engine, the introduction of water in the combustion chamber of a diesel engine is a promising option as vaporization of water reduces adiabatic flame temperature and micro-explosion phenomena lead to improved mixing. In the present study, stable D/W emulsion, with varying water content, up to 3% were prepared using span 80 as a surfactant. The results indicated a reduction in NOx and smoke with increasing water volume fraction in the emulsion compared to diesel baseline. However, beyond 2% water content led to increased ignition delay and higher diffusion phase heat release resulting in noisy engine operation. Therefore, it can be concluded that diesel-water emulsion with 2% water could be used for significant reduction of NOx emissions from diesel and biodiesel operation of a CI Engine.

Effect of Soot Radiation on Flame Temperature, NOx-Emission and Wall Heat Transfer in a Medium Speed Diesel Engine

2002 ◽  
Author(s):  
Pertti Taskinen
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Diesel Engine ◽  
Soot Formation ◽  
Flame Temperature ◽  
Combustion Process ◽  
Measured Data ◽  
Nox Emission ◽  
Fuel Vapor ◽  
Medium Speed

The main aim in this study was to investigate the effect of soot radiation on the maximum flame temperature, the total heat flux to wall and the NOx-emission levels in a medium speed diesel engine. Also the effect of turbulence models (STD or RNG k-epsilon) the combustion and emission results were investigated. The RNG k-epsilon model was modified as part of the velocity dilatation term by using an analysis of rapid spherical distortion. In the modified KIVA2-CFD code the Magnussen EDC (Eddy Dissipation Concept) model was used for the fuel vapor combustion, the Tesner & Magnussen model for the soot formation, the combined Magnussen EDC/Nagle & Strickland-Constable for the soot combustion, the extended Zeldovich model for the NO-formation and the chi-squared model for the spray. Radiative heat transfer was dealt with in two ways, in the first the simplified method was used (pure soot emission) and in the second the radiative transport equation was solved with the discrete ordinate method (DOM). The soot absortion coefficient was calculated with the correlation of Kent & Honnery. The computations were done with and without radiant heat loss in order to observe the effect of soot radiation in the results. The predicted cylinder pressures and the heat release rates in both cases were compared with the corresponding measured data. The soot, NOx and heat flux results were compared to the results obtained from literature, due to the non-availability of measured data. The predicted results are reasonable and behaved correctly. The simulation results show that the effect of soot radiation in the combustion process is remarkable and therefore it has to be taken into consideration when modelling diesel engine processes. Also the modified RNG k-epsilon model yields slightly more realistic combustion results than the STD k-epsilon model.

scholarly journals Biodiesel unsaturation degree effects on diesel engine NOx emissions and cotton wick flame temperature

2016 ◽  
Vol 90 ◽  
pp. 01041 ◽  
Author(s):  
Mohd Fareez Edzuan Abdullah ◽  
Sim Shu Zhing ◽  
Clarence Bilong Bugik
Keyword(s):  
Diesel Engine ◽  
Flame Temperature ◽  
Nox Emissions ◽  
Cotton Wick

Influence of Excess Air Factor on NOx Emissions From a 200 kW Swirl Burner

2015 ◽  
Author(s):  
Abdallah Ahmed ◽  
Essam E. Khalil ◽  
Hatem Kayed ◽  
Mohamed M. A. Hassan
Keyword(s):  
Combustion Chamber ◽  
Air Temperature ◽  
Gas Turbines ◽  
Flame Temperature ◽  
Combustion Process ◽  
Operating Conditions ◽  
Swirl Burner ◽  
Nox Formation ◽  
Excess Air ◽  
Thermal Nox

NOx formation during the combustion process occurs mainly through the oxidation of nitrogen in the combustion air (thermal NOx) and through oxidation of nitrogen with the fuel (prompt NOx). The present study aims to investigate numerically the problem of NOx pollution using a model of combustion chamber with 200 kW swirl burner utilizing propane as fuel. The importance of this problem is mainly due to its relation to the pollutants produced by boiler furnaces and gas turbines, which used widely in thermal industrial plants. Governing conservation equations of mass, momentum and energy, and equations representing the transport of species concentrations, turbulence, combustion and radiation modeling in addition to NOx modeling equations were solved together to present temperature and OH distribution inside the combustion chamber, and the NOx concentration at the combustion chamber exit, at various operating conditions of fuel to air ratio. In particular, the simulation provided more insight on the correlation between the peak flame temperature and the thermal NOx concentration. The results have shown that the peak flame temperature and NOx concentration decrease as the excess air factor λ increases. When considering a fixed value of mass flow rate of fuel, the results show that increasing λ results in a maximum value of thermal NOx concentration at the exit of the combustion chamber at λ = 1.05. As the combustion air temperature increases, and the thermal NOx concentration increases sharply. However, when λ exceeds this value NOx concentration starts to decrease due to the combustion air temperature decrease.

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