Effect of Gasoline Property on Formation of Intake Valve and Combustion Chamber Deposits

The cleanliness of gasoline is related to its components and properties.All commercial gasoline builds up deposits on the engine's injector,intake valve and combustion chamber,which can significantly lower the engine performance and influence exhaust gas emissions.In this study,the intake valve deposits (IVD) and combustion chamber deposits (CCD) produced from combustion of fuel containing 21 v%—42 v% of aromatics and 8 v%—31 v% of olefins have been studied using Ford engine tests,and the characteristics of deposits were studied by IR spectroscopy,TGA and elemental analysis instrument.The test results have shown that deposit formation depends on the fuel composition,especially the aromatic content in the fuel.It is also observed that there are differences in the values of IVD and CCD measured by IR spectrometry and elemental analyses.

Thermal and elemental analysis of the combustion chamber deposits in a large-scale two-stroke marine diesel engine

It is of significance to understand the chemical content of carbon deposits in the large-scale two-stroke(LSTS) marine diesel engine because of adverse effect on the engine performance, oil consumption and emissions. In this work, two different combustion chamber deposits in an LSTS marine diesel engine were studied using thermogravimetry analysis(TGA), elemental analysis(EA) and synchrotron X-ray fluorescence(SXRF). One was on the piston top and the other on the piston land, termed PTCD and PLCD, respectively. For the PTCD sample, the 97% residue in the TGA and 1.4% carbon content in the EA indicated the main compositions of PTCD were metal salts or oxides and ashes, significantly different from the previous findings of the highest carbon content in deposits from the small four stroke engines. The different chemical content between PTCD and PLCD implied higher thermal load in the LSTS marine diesel engine led to a nearly complete thermal decomposition of PTCD. The higher calcium content in PTCD and PLCD indicated the additives of cylinder oil should be the main source of metal content of PTCD and PLCD. Calcium distribution in the SXRF results was indicative of the potential layered structure in PTCD and PLCD. In addition, the appearance of iron on the surface against the piston in PTCD and PLCD indicated iron oxides formation between carbon deposit and piston materials.

Interannual Variation Characteristics of the Atmospheric Dust Deposition on Typical Region of Chaihe Basin

[Objective]The aim was to study the interannual changes of atmospheric dust deposition and quantity of combustible dust-fall in Chaihe basin.[Method]Taking Chaihe Basin in south Dianchi as study area,the atmospheric dust deposition and combustible substances in the residential,chemical area,sand production area and watershed in Chaihe basin were measured.The pollution and interannual changes of atmospheric dust in Chaihe basin were discussed.[Result]In the residential,chemical area,sand production area and watershed,the amount of sand was the highest in sand production area and lowest in the watershed.While the dust amount in the chemical area and watershed areas were lower than sand production area and higher than watershed area.In the four chosen areas,the highest value of dust appeared in autumn and the lowest value appeared in precipitation season.Sand in other months changed and the change scale was large,which indicated that the meteorological condition had large influences on dust.Relevance analysis indicated that the dust in sand production area showed positive relevance to flammable amount of dust.Dust and flammable amount had positive relevance.[Conclusion]The study provided theoretical basis for the atmospheric pollution situation in Chaihe Basin.

Ultraviolet laser photolysis of hydrocarbons for nondiamond carbon suppression in chemical vapor deposition of diamond films

In this work,we demonstrate that ultraviolet(UV)laser photolysis of hydrocarbon species alters the flame chemistry such that it promotes the diamond growth rate and film quality.Optical emission spectroscopy and laser-induced fluorescence demonstrate that direct UV laser irradiation of a diamond-forming combustion flame produces a large amount of reactive species that play critical roles in diamond growth,thereby leading to enhanced diamond growth.The diamond growth rate is more than doubled,and diamond quality is improved by 4.2%.Investigation of the diamond nucleation process suggests that the diamond nucleation time is significantly shortened and nondiamond carbon accumulation is greatly suppressed with UV laser irradiation of the combustion flame in a laser-parallel-to-substrate geometry.A narrow amorphous carbon transition zone,averaging 4 nm in thickness,is identified at the film–substrate interface area using transmission electron microscopy,confirming the suppression effect of UV laser irradiation on nondiamond carbon formation.The discovery of the advantages of UV photochemistry in diamond growth is of great significance for vastly improving the synthesis of a broad range of technically important materials.

Electrophoretic deposition and an investigation of co-dopants effect on luminescence property of Mg2SiO4:Eu3+phosphors

Forsterite particles doped with europium ions（Eu^（3＋）） were synthesized via a solution combustion method. The effect of co-dopants on photoluminescence intensity was described. Different percentages of calcium（Ca^（2＋））, zinc（Zn^（2＋））, barium（Ba^（2＋）） and strontium（Sr^（2＋）） were added to the Mg2SiO4：Eu^（3＋）host.The synthesized sample was characterized by X-ray diffraction, transmission electron microscopy,scanning electron microscopy, spectrofluorometer and the FTIR spectroscopy. X-ray diffraction（XRD）results revealed that dominant phase was forsterite in all samples. Additionally, a negligible amount of periclase phase was recognized in the samples. The average size of the synthesized particles was less than 200 nm. The presence of co-dopant led to an enhancement in the photoluminescent property of the synthesized samples. The maximum increase in photoluminescence intensity was obtained by Ba^（2＋）ions as a co-dopant. Condensed films of photoluminescence particles were produced by utilizing electrophoresis technique to deposit particles. The results showed that polyvinyl pyrrolidone was the best surface modifier to raise the mass deposition of the samples on the substrate.