Simulation of Combustion in a Porous Reactor

2014 ◽  
Author(s):  
Arash Mohammadi ◽  
Mona Benhari
Keyword(s):  
Diesel Engines ◽  
Liquid Fuel ◽  
Fuel Injection ◽  
Numerical Study ◽  
Direct Injection ◽  
Nitrogen Monoxide ◽  
High Porosity ◽  
Lean Mixture ◽  
Cold Condition ◽  
Reduce Emissions

Development of IC engines with low emissions and low fuel consumption causes interest in direct injection engine, especially diesel engines that work with lean mixture. This goal may be achieved with separation of mixture formation and combustion processes, in diesel engines. A practicable way to reach this target is the use of porous medium (PM) inside the combustion chamber. The PM has benefits to enhance the evaporation of droplets in liquid-fuel burners, reduce emissions and minimize instabilities. This paper represents the numerical study of liquid-fuel injection and combustion inside constant-volume chemically inert PM to stabilize lean mixture. 3D numerical results have obtained based on a modified version of KIVA-3V code. Diesel was directly sprayed inside hot and high pressure PM chamber. Complete evaporation and self-ignited was achieved due to the initial temperature of PM. The results in an especial condition have compared with an experimental data in the literature. Effect of injection in cold condition has investigated. Contours of diesel vapor, fluid and solid temperature of PM in a cross section, have shown. Also, effects of pore density on a constant high-porosity PM and mass of spray fuel were studied. The results show considerable reduction in carbon monoxide, nitrogen monoxide and elimination of soot.

Study of Fuel Temperature Effects on Fuel Injection, Combustion, and Emissions of Direct-Injection Diesel Engines

2008 ◽  
Vol 131 (2) ◽  
Author(s):  
Gong Chen
Keyword(s):  
Diesel Engine ◽  
Diesel Engines ◽  
Temperature Effects ◽  
Liquid Fuel ◽  
Fuel Injection ◽  
Direct Injection ◽  
Injection Rate ◽  
Fuel Temperature ◽  
Injection Parameters ◽  
Medium Speed

The influence of inlet liquid fuel temperature on direct-injection diesel engines can be noticeable and significant. The work in this paper investigates the effects of inlet fuel temperature on fuel-injection in-cylinder combustion, and output performance and emissions of medium-speed diesel engines. An enhanced understanding and simplified modeling of the variations in the main fuel-injection parameters affected by inlet fuel temperature are developed. The study indicates that the main injection parameters affected include the injection timing at the injector end relative to the injection-pump actuation timing, the fuel-injection rate, the fuel-injection duration, and the injection spray atomization. The primary fuel temperature effects on the injection parameters are from the fuel bulk modulus of elasticity and the density with the fuel viscosity less significant as the injector-nozzle flow is usually in a turbulent region. The developed models are able to predict the changes in the injection parameters versus the inlet fuel temperature. As the inlet fuel temperature increases, the nozzle fuel-injection-start timing is predicted to be relatively retarded, the injection rate is reduced, and the needle-lift duration is prolonged from the baseline. The variation trends of the engine outputs and emissions versus fuel temperature are analyzed by considering its consequent effect on in-cylinder combustion processes. It is predicted that raising fuel temperature would result in an increase in each of CO, HC, PM, and smoke emissions, and in a decrease in NOx, and may adversely affect the fuel efficiency for a general type of diesel engine at a full-load condition. The experimental results of the outputs and emissions from testing a medium-speed four-stroke diesel engine agreed with the trends analytically predicted. The understanding and models can be applied to compression-ignition direct-injection liquid fuel engines in general.

Study of Fuel Temperature Effects on Fuel Injection, Combustion and Emissions of Direct-Injection Diesel Engines

2003 ◽  
Author(s):  
Gong Chen
Keyword(s):  
Diesel Engines ◽  
Temperature Effects ◽  
Liquid Fuel ◽  
Fuel Injection ◽  
Direct Injection ◽  
Injection Rate ◽  
Fuel Temperature ◽  
Injection Parameters ◽  
Medium Speed ◽  
Performance And Emissions

The influence of inlet liquid fuel temperature on direct-injection diesel engines can be noticeable and significant. The work in this paper investigates the effects of inlet fuel temperature on fuel injection, in-cylinder combustion, and performance and emissions of medium-speed diesel engines. An enhanced understanding and simplified modeling of the variations in main fuel injection parameters affected by inlet fuel temperature are developed. The study indicates that the main affected injection parameters include the injector injection timings, the fuel injection rate, the fuel injection duration, and the injection spray atomization. The primary fuel temperature effects on the injection parameters are from the fuel bulk modulus of elasticity and the density with the fuel viscosity less significant as the injector nozzle flow is in a turbulent region. The developed models can predict the changes in the injection parameters versus fuel temperature. As inlet fuel temperature increases, the nozzle fuel-injection-start timing is predicted to be retarded, the injection rate to be reduced, and the needle-lift duration to be prolonged from the baseline. The variation trends of the engine performance and emissions versus fuel temperature are analyzed by considering its consequent effect on in-cylinder combustion processes. It is predicted that raising fuel temperature would result in an increase in CO, HC, PM and smoke emissions, and in a decrease in NOx. The experimental results of the output performance and emissions from testing a medium-speed four-stroke diesel engine agreed with the trends analytically predicted. The understanding and models developed can apply to compression-ignition direct-injection liquid fuel engines in general.

Numerical Study of Combustion in a Porous Medium With Liquid Fuel Injection

2017 ◽  
Author(s):  
Arash Mohammadi ◽  
Mona Benhari ◽  
Mehrdad Nouri Khajavi
Keyword(s):  
Porous Medium ◽  
Free Volume ◽  
Liquid Fuel ◽  
Fuel Injection ◽  
Soot Formation ◽  
Numerical Study ◽  
Three Dimensional ◽  
Nitrogen Monoxide ◽  
Maximum Pressure ◽  
Fluid Temperature

Porous medium (PM) has potential advantage to enhance evaporation of droplets in liquid-fuel burners, low emissions and minimize instabilities of combustion. This paper represents the numerical study of liquid-fuel injection, evaporation, and combustion inside constant-volume chemically inert PM. It stabilizes lean combustion and decreases emissions. Three-dimensional numerical results were obtained based on a modified KIVA-3V code. Diesel fuel is directly injected into chamber for two cases, free volume and PM reactor. With high initial temperature, fast evaporation and self-ignited occur. The results for specified conditions were compared with experimental data in literature. Effects of injection on mixture formation was investigated. Distribution of diesel vapor, fluid and solid temperature of PM in a cutting plane, were shown. Diagram of diesel vapor, CO, NO, Soot, solid and fluid temperature versus time for different mass of injected fuel, were presented. Also, results of diesel vapor, pressure and temperature in free volume and PM reactor have compared. The results show considerable reduction in maximum pressure and temperature, carbon monoxide, nitrogen monoxide and soot formation in PM reactor in comparison with free volume.

scholarly journals Use of biogas to power diesel engines with common rail fuel systems

2018 ◽  
Vol 182 ◽  
pp. 01018
Author(s):  
Sławomir Wierzbicki ◽  
Michał Śmieja
Keyword(s):  
Diesel Engines ◽  
Alternative Energy ◽  
Liquid Fuel ◽  
Fossil Fuels ◽  
Fuel Injection ◽  
Raw Materials ◽  
Common Rail ◽  
Dual Fuel ◽  
Alternative Energy Sources ◽  
Study Results

The limited resources of fossil fuels, as well as the search for a reduction in emissions of carbon dioxide and other toxic compounds to the atmosphere have prompted the search for new, alternative energy sources. One of the potential fuels which may be widely used in the future as a fuel is biogas which can be obtained from various types of raw materials. The article presents selected results as regards the effects of the proportion of biogas of various compositions on the course of combustion in a dual-fuel diesel engine with a Common Rail fuel system. The presented study results indicate the possibility for the use of fuels of this type in diesel engines; although changes are necessary in the manner of controlling liquid fuel injection.

Numerical Studies of Glow Plug Shield on Natural Gas Ignition Characteristics in a CI Engine

2016 ◽  
Author(s):  
Kang Pan ◽  
James S. Wallace
Keyword(s):  
Natural Gas ◽  
Ignition Delay ◽  
Fuel Injection ◽  
Numerical Study ◽  
Direct Injection ◽  
Fuel Mixture ◽  
Injection Angle ◽  
Glow Plug ◽  
Gas Ignition ◽  
Ignition And Combustion

This paper presents a numerical study on fuel injection, ignition and combustion in a direct-injection natural gas (DING) engine with ignition assisted by a shielded glow plug (GP). The shield geometry is investigated by employing different sizes of elliptical shield opening and changing the position of the shield opening. The results simulated by KIVA-3V indicated that fuel ignition and combustion is very sensitive to the relative angle between the fuel injection and the shield opening, and the use of an elliptical opening for the glow plug shield can reduce ignition delay by 0.1∼0.2ms for several specific combinations of the injection angle and shield opening size, compared to a circular shield opening. In addition, the numerical results also revealed that the natural gas ignition and flame propagation will be delayed by lowering a circular shield opening from the fuel jet center plane, due to the blocking effect of the shield to the fuel mixture, and hence it will reduce the DING performance by causing a longer ignition delay.

Modeling of Internal and Near-Nozzle Flow for a Gasoline Direct Injection Fuel Injector

2016 ◽  
Vol 138 (5) ◽  
Author(s):  
Kaushik Saha ◽  
Sibendu Som ◽  
Michele Battistoni ◽  
Yanheng Li ◽  
Shaoping Quan ◽  
...  
Keyword(s):  
Liquid Fuel ◽  
Numerical Study ◽  
Direct Injection ◽  
Computational Cost ◽  
Volume Averaging ◽  
Operating Conditions ◽  
Gasoline Direct Injection ◽  
Superheated Liquid ◽  
Fuel Injector ◽  
Flash Boiling

A numerical study of two-phase flow inside the nozzle holes and the issuing spray jets for a multihole direct injection gasoline injector has been presented in this work. The injector geometry is representative of the Spray G nozzle, an eight-hole counterbore injector, from the engine combustion network (ECN). Simulations have been carried out for a fixed needle lift. The effects of turbulence, compressibility, and noncondensable gases have been considered in this work. Standard k–ε turbulence model has been used to model the turbulence. Homogeneous relaxation model (HRM) coupled with volume of fluid (VOF) approach has been utilized to capture the phase-change phenomena inside and outside the injector nozzle. Three different boundary conditions for the outlet domain have been imposed to examine nonflashing and evaporative, nonflashing and nonevaporative, and flashing conditions. Noticeable hole-to-hole variations have been observed in terms of mass flow rates for all the holes under all the operating conditions considered in this study. Inside the nozzle holes mild cavitationlike and in the near-nozzle region flash-boiling phenomena have been predicted when liquid fuel is subjected to superheated ambiance. Under favorable conditions, considerable flashing has been observed in the near-nozzle regions. An enormous volume is occupied by the gasoline vapor, formed by the flash boiling of superheated liquid fuel. Large outlet domain connecting the exits of the holes and the pressure outlet boundary appeared to be necessary leading to substantial computational cost. Volume-averaging instead of mass-averaging is observed to be more effective, especially for finer mesh resolutions.

A Numerical Study of NOx Reduction for a DI Diesel Engine With Complex Geometry

2004 ◽  
Vol 126 (1) ◽  
pp. 13-20 ◽  
Author(s):  
Renshan Liu ◽  
Chao Zhang
Keyword(s):  
Diesel Engine ◽  
Thermal Efficiency ◽  
Fuel Injection ◽  
Complex Geometry ◽  
Numerical Study ◽  
Direct Injection ◽  
Nox Reduction ◽  
Geometrical Parameters ◽  
Injection Timing ◽  
Di Diesel Engine

A numerical study of NOx reduction for a Direct Injection (DI) Diesel engine with complex geometry, which includes intake/exhaust ports and moving valves, was carried out using the commercial computational fluid dynamics software KIVA-3v. The numerical simulations were conducted to investigate the effects of engine operating and geometrical parameters, including fuel injection timing, fuel injection duration, and piston bowl depth, on the NOx formation and the thermal efficiency of the DI Diesel engine. The tradeoff relationships between the reduction in NOx and the decrease in thermal efficiency were established.

Predicting Hydrocarbon Emissions From Direct Injection Diesel Engines

2002 ◽  
Vol 124 (3) ◽  
pp. 708-716 ◽  
Author(s):  
P. A. Lakshminarayanan ◽  
N. Nayak ◽  
S. V. Dingare ◽  
A. D. Dani
Keyword(s):  
Diesel Engines ◽  
Fuel Injection ◽  
Direct Injection ◽  
Injection System ◽  
Hydrocarbon Emissions ◽  
Operating Parameters ◽  
Fuel Injection System ◽  
Lean Combustion ◽  
Medium Speed ◽  
Hc Emissions

Hydrocarbon (HC) emissions from direct injection (DI) diesel engines are mainly due to fuel injected and mixed beyond the lean combustion limit during ignition delay and fuel effusing from the nozzle sac at low pressure. In the present paper, the concept has been developed to provide an elegant model to predict the HC emissions considering slow burning. Eight medium speed engines differing widely in bores, strokes, rated speeds, and power were studied for applying the model. The engines were naturally aspirated, turbocharged, or turbocharged with intercooling. The model has been validated by collecting data on HC emission, and pressures in the cylinder and in the fuel injection system from the experimental engines. New coefficients for the correlation of HC with operating parameters were obtained and these are different from the values published earlier, based on single-engine experiments.

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