Qizhao Lin

Impact of ferrocene on the nanostructure and functional groups of soot in a propane/oxygen diffusion flame

This study presents the effect of ferrocene ((C5H5)2Fe) on the soot oxidation activity by influencing the nanostructure and molecular structure of soot. Soot particles were obtained at different heights from propane/oxygen flames without and with ferrocene added to the fuel, respectively. The fringe properties of soot were compared using the skeleton images extracted from the high-resolution transmission electron microscopy images of soot particles. Near-edge X-ray absorption fine structure spectroscopy was used to characterize the carbon chemistry of soot particles. It was found that ferrocene reduced the degree of graphitization of soot by changing its fringe length, tortuosity, and separation distance, and these effects were much more obvious near the flame terminus. These changes may be related to ferrocene dropping the flame temperature there. Fe from (C5H5)2Fe reacting with OH and O radicals decreased the oxygen-containing functional groups of soot and affected its aromatic structure after the addition of (C5H5)2Fe to the flame. The inner cores of soot particles were also much bigger due to partial oxidation. Thermogravimetric analysis revealed that ferrocene promoted the soot oxidation at low temperatures.

Gas emissions from blends of bituminous coal and biomass chars under different pyrolysis conditions

ABSTRACT In this work, thermal behavior and gas emission characteristics of coal, different kinds of biomass chars, and their blends were evaluated by using the thermogravimetric analyzer coupled with a mass spectroscope. The chars were prepared from wheat straw at 300°C and 500°C under N2 and CO2 atmosphere, respectively. The results show that the pyrolysis temperature has a greater effect on the combustion characteristics of biomass char than the pyrolysis atmosphere. NOx emissions were reduced effectively with the addition of biomass chars. The study also reveals that there is an obvious improvement in the combustion behavior of coal when blended with biomass chars.

Macroscopic spray characteristics of long-chain alcohol-biodiesel fuels in a constant volume chamber:

In this research, three basic macroscopic spray characteristics (spray tip penetration, spray cone angle, and spray area) of long-chain alcohol-biodiesel blends were studied to investigate the differences of macroscopic spray characteristics of long-chain alcohol-biodiesel blends with different mixing ratios and to further investigate the effects of blending long-chain alcohols into biodiesel on the spray characteristics. Two kinds of long-chain alcohols, n-butanol, and n-pentanol, were selected to study effects of difference kinds of long-chain alcohols on macroscopic spray characteristics of long-chain alcohol-biodiesel blends. Results show that with the increase of proportion of n-butanol or n-pentanol in blends, spray tip penetration decreased while spray cone angle and spray area increased; in terms of the effects brought by different long-chain alcohols, n-pentanol-biodiesel blends showed slightly longer spray tip penetration, smaller spray cone angle and smaller spray area compared to n-butanol-biodiesel blends in the same mixing ratios, and the difference trends between those two kinds blends could easily be opposite due to the very similar properties of n-butanol and n-pentanol. Furthermore, a modified spray tip penetration model was proposed based on previous model and showed good agreement with experimental results.

Spray Characteristics of n -Butanol in a High-Pressure Common-Rail Injection System

AbstractThis study was conducted to investigate the spray characteristics of n-butanol, using a diesel spray for comparison. Spray tip penetration and spray cone angle were tested and analyzed. A h...

Experimental study of the effect of n-butanol additive on spray characteristics of biodiesel in a high-pressure common-rail injection system

The aim of this study was to investigate the spray characteristics of biodiesel and n-butanol/biodiesel blended fuel. The spray tip penetration and the spray cone angle were tested and analyzed. A constant volume chamber and high-speed camera were used to observe the spray evolution and a common-rail system was employed to change the injection pressure. The results show that the spray tip penetration and the spray cone angle of biodiesel are larger than those of blended fuel in most cases. n-Butanol additive changes the relationship between angle and density ratio to a certain degree. The experimental trend lines support the penetration model proposed by Hiroyasu and Arai in terms of similar proportional relation on time after start of injection, and the empirical equations provide reasonable agreement with the experimental data of the spray tip penetration.

Experimental investigations of kerosene sprays in pressurized evaporating environments

Experiments of kerosene spray with single-hole solenoid injector in the pressurized nonevaporating and evaporating environments, in which the ambient pressure ranges from 1.4 MPa to 4.8 MPa and the ambient temperature includes 300 K, 343 K, and 423 K, are carried out with high-speed Schlieren photography to investigate the breakup regimes and the macro-characteristics like penetration, projected spray area, and spray cone angle. Repetitive experiments are conducted to analyze the penetration repeatability. The comparison between the experimental penetrations and the predicted ones by the existing correlations reveals that the deviations between the experimental data and the predictions rise as the ambient temperature rises. Therefore, a new modified correlation is proposed to predict the penetration of kerosene spray in the nonevaporating and evaporating environments, which fits the experimental data better than the existing correlations. The breakup regimes in primary breakup and secondary breakup are discussed respectively. The projected spray area is analyzed under different ambient pressures at different ambient temperatures. Finally, it is found that the spray cone angle remains almost the same under different ambient pressures after it reduces sharply before 0.5 ms. The macro-characteristics discussed in the present study are important for the performance and emissions of aeronautical engines or diesel engines fuelled by kerosene as a substitution.

Liftoff behavior and combustion characteristic of jet flame in a coflow burner

ABSTRACT Stabilization and autoignition mechanisms of lifted flames have been widely investigated to improve combustion efficiency and safety of combustion equipment. This paper focuses on liftoff behavior and combustion characteristic of methane and propane flames under various coflow conditions in a coflow burner. Unlike the case of free jet flame in ambient air, the different tendencies of liftoff height changes with jet velocity for both methane and propane flames in vitiated coflow illustrate a transition from conventional combustion to Moderate & Intense Low Oxygen Dilution (MILD) combustion. Flame temperature difference with radial position measured by primary spectrum pyrometry proves the transition regime.

Experimental study of spray characteristics of biodiesel blending with diethyl carbonate in a common rail injection system

The objective of this paper is to investigate the spray macroscopic characteristics of biodiesel, diethyl carbonate (DEC)-biodiesel blends and diesel fuel based on a common-rail injection system. The spray tip penetration, spray cone angle and the spray projected area were measured through a high-speed photography method. The experimental results reveal that injection pressure and ambient pressure have significant effects on the spray characteristics. Higher injection pressure makes the spray tip penetration increase, while higher back pressure inside the chamber leads to the enlargement of the spray cone angle. The addition of DEC causes the blends fuels to have a shorter penetration and larger spray projected area, which reveals the potential capacity to improve the atomization process compared with biodiesel. The estimation of spray droplet size indicates that DEC30 generates a smaller Sauter mean diameter (SMD) because of its lower surface tension and viscosity. Model predictions were illustrated and compared with current work.

Experimental and Theoretical Analysis of the Spray Characteristics of a High-Pressure Common-Rail Injection System Fueled with Neat Biodiesel, Ethanol-Biodiesel Blends, and Neat Diesel Fuel

AbstractIn this study, the spray and atomization characteristics of neat biodiesel, ethanol-biodiesel blends (BDEs), and neat diesel in a high-pressure common-rail injection system were investigate...