柴油机含氧燃料的研究进展

综述了传统的柴油机含氧燃料的研究进展 ,重点讨论了柴油机含氧燃料植物油及其甲酯、生物质热解燃料、醇类燃料和醚类燃料的理化性质及其在柴油机上的应用。可以看出 :含氧燃料能有效地降低柴油机的微粒排放。但植物油的不稳定性和燃烧时结焦限制了它在柴油机上的应用。甲醇和乙醇与柴油互溶性较差 ,需要寻找适合的添加剂来解决 ;生物质热解燃料需改进生产工艺。

煤热解过程中硫元素释放进展研究

燃料热解过程中的硫元素迁移转化路径主要与燃料中硫元素的赋存形态有关。有机硫和无机硫在热解过程中的表现差异很大,但同时有机硫和无机硫以及燃料中的其他成分几者之间的相互作用也会对热解过程中硫元素的迁移转化路径产生显著的影响。

固液发动机燃面退移控制因素分析

为获得固液发动机固体燃料燃面退移的控制因素和机理,开展了数值仿真和试验研究。建立二维轴对称计算模型,考虑燃料与氧化剂的混合燃烧和流动过程,计算得到了固液发动机工作过程中的温度、压强、速度和组分的分布,以及不同时刻固体燃料的燃面形貌。仿真与试验结果的对比证明了计算方法的有效性。结果表明:固液发动机的燃面呈现显著的非平行退移特征;燃烧室压强对燃面退移不均匀性的影响可忽略;控制燃面退移的主要因素是燃气传向固体燃料表面的热流密度,燃料表面的温度变化是宏观表现。在靠近喷嘴位置,燃面退移的热量传递主要受燃烧反应过程控制,而靠近喷管处燃面退移的热量传递主要受燃气流动过程控制。研究为固液发动机的装药优化设计和高效燃烧组织提供了理论依据。

Investigation of heat sink of endothermic hydrocarbon fuels

Endothermic hydrocarbon fuels are advanced coolants for high-temperature structures of spacecraft. No data of tested-cooling-ability of endothermic fuels have been broadly discussed in literature. In this work a high-temperature flow calorimeter was designed, and the cooling capacity of six different hydrocarbon fuels were measured. Experimental results showed that these hydrocarbon fuels have capacity for cooling high-temperature structures, and that the cooling capacity of fuel N-1 can reach 3.15 M J/kg, which can nearly satisfy the requirement of thermal management for a Mach 3 cruise aircraft, whose heat sink requirement is about 3.5 M J/kg. The endothermic velocity of hydrocarbon fuels was also measured by the calorimeter.

Fuel consumption study on introducing pyrolyzed DME or ethanol into diesel engine

The present work studied fuel consumption through experiments on a diesel engine. In order to obtain lower BSFC （brake specific fuel consumption）, DME （dimethyl ether） is heated and introduced into air intake, together with fueling emulsified fuel to diesel engine. Results show that BSFC can decrease about 10% and diesel fuel consumption alone can decrease 18%. High saving rate of BSFC up to 10% is also acquired using ethanol instead of DME. To achieve high saving rate of BSFC, the heating temperature of about 1000 K is needed for DME operation, while the diesel engine exhaust temperature of about 750 K is suitable for ethanol. Hydrogen produced in DME or ethanol pyrolysis and the combustion characters of emulsified fuel are considered as main reasons for the excellent fuel saving. Besides, the technique adopted in the present work is extremely easy to be utilized, and may be firstly adopted on diesel engines for power plants, trains, and ships etc.

Improved properties of carbon fiber paper as electrode for fuel cell by coating pyrocarbon via CVD method

The fabrication of a pyrocarbon coated carbon paper and its application to the gas diffusion lay(GDL) of proton exchange membrane(PEM) fuel cell were described.This carbon paper was fabricated by using conventional carbon paper as the precursor,and coating it with pyrocarbon by pyrolyzing propylene via the chemical vapor deposition(CVD) method.For comparison,conventional carbon paper composites were also prepared by using PAN-based carbon fiber felt as the precursor followed by impregnation with resin,molding and heat-treatment.SEM characterization indicates that pyrocarbon is uniformly deposited on the surface of the fiber in the pyrocarbon coated carbon paper and made the fibers of carbon felt bind more tightly.In contrast,there are cracks in matrix and debonding of fibers due to carbonization shrinkage in the conventional carbon paper.Property measurements show that the former has much better conductivity and gas permeability than the latter.In addition,current density-voltage performance tests also reveal that the pyrocarbon coating can improve the properties of carbon paper used for electrode materials of fuel cell.

Torrefied Pellets as Fuel for Two-Stage Technology of Biomass Conversion into Synthesis Gas

One of the most important properties of the torrefied pellets, along with high calorific value, is their hydrophobicity. Inability to absorb moisture and self-destruct under its influence determine possibility of using of pellets in the pyrolysis reactor. For the technology of two-stage thermal processing of biomass, developed at the Joint Institute for High Temperatures, the amount of synthesis gas which can be obtained from one kilogram of torrefied pellets is also important. A construction of the pilot torrefaction reactor powered by flue gas is shown. The results of experimental investigations of hydrophobicity of torrefied pellets produced by the reactor and quantity of synthesis gas which can be obtained by two-stage thermal processing of the pellets are presented. It is shown that torrefaction allows simplifying the process of conversion of pellets into synthesis gas without significant reduction in the volume of the gas.

De-polymerization of Waste Polymers to Produce Hydrocarbon Fuel Utilizing Thermal Degradation

Waste plastics are one of the biggest environmental concerns the world faces today. Waste plastics exposure to the environment is very hazardous. Over time waste plastics photo-degrade and become very tiny dust particles. These dust particles contain very harmful compounds including benzene, sulfur, carbon and many others. According to studies, waste plastic pollutions are one of the biggest reasons for the depletion of the ozone layer and contributor of global warming. Many scientists have been trying to figure out how to utilize these waste plastics and convert them into useful energy sources. It is possible to convert waste plastics into energy because they are made from petroleum. Scientists have succeeded in developing many methods including pyrolysis, catalytic cracking, thermal degrading and others. The purpose of this experiment is to convert these environmentally harmful waste materials into useful energy source using simple and viable methods. A particular thermal degradation process was successful in extracting fuel from waste plastics at 370-420 ~C. In this paper we will discuss our performed experiment and provide detailed analysis of the produced fuel. Thorough instrumental analysis of the produced fuel showed very considerable results including high energy contents, low levels of harmful emissions and compatibility with various types of existing appliances.

Influence of Cell Components Structure on Heat and Mass Transfer Phenomena in Single-Cell PEFC

The purpose of this study is to point out the dominant factor of heat and mass distribution in single-cell PEFC （polymer electrolyte fuel cell）. The numerical simulation by simple 3D model to clarify the influence of cell components structure on heat and mass transfer phenomena as well as power generation experiment and measurement of in-plane temperature distribution by thermograph was carried out. From the simulation, the gas channel pitch of separator was the key factor to unify in-plane distribution of temperature and gas concentration on reaction surface in cell. The compression of GDL （gas diffusion layer） by cell binding caused wider distribution of mass concentration in GDL. From the experiment, the power generation performance was promoted with decreasing gas channel pitch. The temperature range in observation area was reduced with decreasing gas channel pitch. It can be concluded that the power generation performance is promoted by decreasing gas channel pitch.

Ash-free coal as fuel for direct carbon fuel cell

This work describes the performance of the direct carbon fuel cell(DCFC)fuelled by ash-free coal.Employing coal in the DCFC might be problematic,mainly because of the ash deposition after the cell reactions.In the study,the carbonaceous ash-free component of coal is obtained,which is then evaluated as the DCFC fuel and compared with raw coal,active carbon,carbon black,and graphite.The electrolyte-supported SOFC structure is adapted to build the DCFC.The DCFC based on the ash-free coal fuel exhibits good performance with regard to the maximum power density,day-by-day measurements,and durability at continuous run.When the carbon fuels are internally gasified to H2 and CO,the power density is generally much improved,compared to N2 pyrolysis environment.The power generation is most likely related to the concentration of pyrolyzed gases as well as the electrochemical reactivity of the solid carbon.