二甲基醚/天然气双燃料均质压燃过程详细化学反应动力学数值模拟研究(Ⅰ)--二甲基醚反应机理研究

应用零维详细化学反应动力学模型对二甲基醚均质压燃燃烧反应机理进行了数值模拟研究。结果表明二甲基醚放热反应为典型的双阶段放热反应，经历低温反应、负温度系数区域和高温反应三个过程．高温反应又分为蓝焰和热焰两个阶段。二甲基醚自燃着火由过氧化氢(H2O2)分解所控制，甲醛(CH2O)是过氧化氢的主要来源。基于化学敏感性分析．得到了均质压燃二甲基醚反应的主要途径：首先是二甲基醚脱氢，经过两次加氧后得到甲醛基；然后生成甲酸基(HCO)；最后生成一氧化碳(CO)。在二甲基醚的氧化反应过程中，氢氧根(OH)发挥着重要的作用，它是二甲基醚脱氢反应和CO氧化过程中的主要自由基。     

低沸点燃料二甲醚润滑性评估实验台的研制

二甲醚在常温常压下为气态,不能用传统方法评估其润滑性能。根据低沸点燃油的物理特性和高频往复机(HFRR)的基本原理,设计可加压的高频往复机,初步搭建用于低沸点燃油的摩擦磨损试验台架,并采用常规燃油进行油品的可分辨性试验。结果表明,该台架可以用于评价不同油品的润滑性,为二甲醚等低沸点燃油润滑性能评估方法的建立奠定了基础。     

甲醇气相法制备二甲醚常见问题及解决措施

结合200kt/a二甲醚装置实际运行状况,研究二甲醚装置在运行过程中出现的问题如汽化塔釜液pH值较低造成管线严重腐蚀、反应器床层超温等,针对问题采取相应方案。结果表明,通过系列的技改技措,有效的解决了影响装置安全生产的不利因素。     

二甲醚与液化石油气混合液自然气化动态模拟

讨论了二甲醚与液化石油气混合液自然气化过程中气相组成的动态变化,建立了计算模型,分析了动态模拟结果,提出了二甲醚与20Y液化石油气掺混的比例.     

The potential of di-methyl ether (DME) as an alternative fuel for compression-ignition engines: A review

This paper reviews the properties and application of di-methyl ether (DME) as a candidate fuel for compression-ignition engines. DME is produced by the conversion of various feedstock such as natural gas, coal, oil residues and bio-mass. To determine the technical feasibility of DME, the review compares its key properties with those of diesel fuel that are relevant to this application. DME’s diesel engine-compatible properties are its high cetane number and low auto-ignition temperature. In addition, its simple chemical structure and high oxygen content result in soot-free combustion in engines. Fuel injection of DME can be achieved through both conventional mechanical and current common-rail systems but requires slight modification of the standard system to prevent corrosion and overcome low lubricity. The spray characteristics of DME enable its application to compression-ignition engines despite some differences in its properties such as easier evaporation and lower density. Overall, the low particulate matter production of DME provides adequate justification for its consideration as a candidate fuel in compression-ignition engines. Recent research and development shows comparable output performance to a diesel fuel led engine but with lower particulate emissions. NO_x emissions from DME-fuelled engines can meet future regulations with high exhaust gas recirculation in combination with a lean NO_x trap. Although more development work has focused on medium or heavy-duty engines, this paper provides a comprehensive review of the technical feasibility of DME as a candidate fuel for environmentally-friendly compression-ignition engines independent of size or application.     

Effect of pressure on direct synthesis of DME from syngas over metal-pillared ilerites and metal/metal-pillared ilerites

The effect of pressure on the direct synthesis of dimethyl ether (DME) from syngas over metal (Cu, Zn) pillared ilerites and metal (Cu, Zn) impregnated metal-pillared ilerites was explored. The prepared catalysts were characterized by XRD, BET, ICP-AES, SEM and FT-IR. The direct DME synthesis reaction was carried out in a differential fixed bed reactor with the prepared catalysts at various pressures (10, 20, 30 bar), 250°C and H₂/CO ratio of 2. The Cu/Zn-pillared ilerite catalyst showed the highest catalytic activity among the prepared catalysts at 20 bar, in which CO conversion was about 62% and DME selectivity was about 89%. CO conversion increased with pressure, and DME selectivity increased with pressure in the range of 10–20 bar, and above the pressure slightly decreased with pressure. The optimum pressure for this reaction was 20 bar.     

Numerical study of effects of reformed exhaust gas recirculation (REGR) on dimethyl ether HCCI combustion

The effects of reformed exhaust gas recirculation (REGR) on combustion and emissions of dimethyl ether (DME) homogeneous charge compression ignition (HCCI) engines are studied by multi-dimensional CFD coupled with chemical kinetic model. The results show that REGR combing EGR and DME reformed gases (DRG) improves combustion and emissions. REGR can delay ignition time by both EGR and DRG, and makes main combustion closer to top dead center (TDC), which is beneficial to reducing compression negative work and broadening load range of HCCI engines. The interaction of DRG and EGR helps avoid too high pressure rise rate or low power performance when being applied independent of each other. HC, CO and NO_x emissions can be controlled simultaneously by REGR. Both advantages of DRG and EGR are used to decrease the emissions of HCCI engines by REGR, while the disadvantages of high emissions are alleviated when one of them is applied.     

合成气直接制取二甲醚催化剂的制备因素及其应用

研究了ＣｕＯ／ＺｎＯ／Ａｌ２Ｏ３和ＣｕＯ－ＺｎＯ－Ａｌ２Ｏ３／ＨＺＳＭ－５催化剂的制备方法及合成反应条件对合成气直接制取二甲醚反应的影响。结果表明，采用共沉淀沉积法制备催化剂，３５０°Ｃ下焙烧，２３０～２４０°Ｃ下还原ＣｕＯ／ＺｎＯ／Ａｌ２Ｏ３催化剂的活性最高。ＣｕＯ－ＺｎＯ－Ａｌ２Ｏ３／ＨＺＳＭ－５催化剂上合成反应的适宜条件：温度２７０～３００°Ｃ，压力４．０ＭＰａ，空速１５００ｈ－１，Ｈ２ＣＯ＝２～２．８（ｍｏｌ比），原料气中ＣＯ２的浓度为５％（ｖ）。     

气穴现象对DME(二甲醚)喷油特性影响的仿真研究

以一个实际的高压共轨喷油器为原型,采用数值仿真软件对其进行了分析与建模,并且利用该模型对DME的燃料喷射特性进行了仿真计算,重点分析研究了气穴现象对DME喷射特性的影响,同时提出了通过改进该共轨喷油器的结构参数,包括减小进油节流孔直径、增大出流节流孔直径以及降低针阀弹簧预紧力等来减小气穴对DME喷射特性的影响,为DME共轨喷油器的改进提供了参考依据。     

二甲醚发动机燃油喷射过程的数值模拟及其试验研究

针对采用普通油泵—油管—油嘴燃油系统的二甲醚发动机,建立了燃油喷射过程的数学模型,通过对不同工况下燃用DME和柴油的燃油喷射过程的数值模拟与计算结果的试验验证,揭示了二甲醚发动机燃油喷射过程的物理本质及其特性参数的变化规律。研究表明,由于DME具有较高的可压缩性,致使其泵端与嘴端压力上升及下降都较柴油缓慢,压力上升始点延迟,实际喷油始点滞后,嘴端油管压力峰值较低,高压油管中的残余压力较高,较易出现二次喷射现象。