Soot processes in compression ignition engines

New Combustion Concept for Ultra-Clean and High-Efficiency Small DI Diesel Engines

It is generally accepted that emissions of nitrogen oxides (NOx) increase as the volume fraction of biodiesel increases in blends with conventional diesel fuel. While many mechanisms based on biodiesel effects on in- cylinder processes have been proposed to explain this observation, a clear understanding of the relative importance of each has remained elusive. To gain further insight into the cause(s) of the biodiesel NOx increase, experiments were conducted in a single- cylinder version of a heavy-duty diesel engine with extensive optical access to the combustion chamber. The engine was operated using two biodiesel fuels and two hydrocarbon reference fuels, over a wide range of loads, and using undiluted air as well as air diluted with simulated exhaust gas recirculation. Measurements were made of cylinder pressure, spatially integrated natural luminosity (a measure of radiative heat transfer), engine-out emissions of NOx and smoke, flame lift-off length, actual start of injection, ignition delay, and efficiency. Adiabatic flame temperatures for the test fuels and a surrogate #2 diesel fuel also were computed at representative diesel-engine conditions. Results suggest that the biodiesel NOx increase is not quantitatively determined by a change in a single fuel property, but rather is the result of a number of coupled mechanisms whose effects may tend to reinforce or cancel one another under different conditions, depending on specific combustion and fuel characteristics. Nevertheless, charge-gas mixtures that are closer to stoichiometric at ignition and in the standing premixed autoignition zone near the flame lift- off length appear to be key factors in helping to explain the biodiesel NOx increase under all conditions. These differences are expected to lead to higher local and average in-cylinder temperatures, lower radiative heat losses, and a shorter, more-advanced combustion event, all of which would be expected to increase thermal NOx emissions. Differences in prompt NO formation and species concentrations resulting from fuel and jet-structure changes also may play important roles.

An Experimental Investigation of the Origin of Increased NOx Emissions When Fueling a Heavy-Duty Compression-Ignition Engine with Soy Biodiesel

Experiments on the effects of temperature T and equivalence ratio Φ on soot formation at high pressures up to 5 MPa were conducted. Discussion of the trajectory in relation to both soot and NO formation region gives suggestion of a possibility of high temperature ― rich mixture combustion to reduce particulate formation in diesel engines

High Combustion Temperature for the Reduction of Particulate in Diesel Engines

Combustion behavior of single particles from three different coal ranks and from sugar cane bagasse in O2/N2 and O2/CO2 atmospheres

A Study on the Time and Space Resolved Measurement of Flame Temperature and Soot Concentration in a D. I. Diesel Engine by the Two-Color Method

Results are presented of optical measurement of the flame temperature and KL factor (soot concentration) in a direct injection diesel engine using the two-color method. In the latter stages of combustion, the infrared two-color method gave a lower value than the visible two-color method, the difference being enhanced with crank angle advancement. The KL factor value obtained by the visible method was about half that of the infrared method. These differences were caused by the alpha index (wavelength dependency of flame emissivity) change in the infrared region during the combustion period; the effect at both wave lengths of uneven distributions of temperature and soot concentration along the optical path; and the effect of the reflection of the opposite wall on the infrared method. The optical characteristics and other instrumentation problems of the two-color method at both wavelengths are also discussed.

A Study on the Application of the Two–Color Method to the Measurement of Flame Temperature and Soot Concentration in Diesel Engines

Formation et oxydation des particules de suie dans un moteur diesel a injection directe. Etude experimentale par la methode des deux couleurs

Formation and Oxidation Processes of Soot Particulates in a D. I. Diesel Engine — An Experimental Study via the Two-Color Method

The two-color method for measuring the visible wavelength radiation from soot particles in flames was closely studied as a possible technique for measuring flame temperature and soot concentration in diesel engines. The accuracy of the temperature calibration of the measuring equipment was assured by a newly developed, high-temperature black-body furnace and a standard tungsten lamp. The emissivity of diesel flames, the most important value in this method, was investigated by the spectroscopic analysis of soot sampled from a diesel flame and by comparative measurements between the two-color method and the emission-absorption method. When the two-color method was applied to a direct injection diesel engine, the time and space resolved values of temperature and soot concentration were obtained for the first time.

A study on the time and space resolved measurement of flame temperature and soot concentration in a d.i. (direct injection) diesel engine by the two-color method

Yukio Matsui

Papers

A Study on the Time and Space Resolved Measurement of Flame Temperature and Soot Concentration in a D. I. Diesel Engine by the Two-Color Method

A Study on the Application of the Two–Color Method to the Measurement of Flame Temperature and Soot Concentration in Diesel Engines

Formation and Oxidation Processes of Soot Particulates in a D. I. Diesel Engine — An Experimental Study via the Two-Color Method

A study on the time and space resolved measurement of flame temperature and soot concentration in a d.i. (direct injection) diesel engine by the two-color method

A Gas Sampling Study on the Formation Processes of Soot and NO in a DI Diesel Engine