Regeneration of diesel particulate filter using nonthermal plasma without catalyst

Regulations regarding automotive diesel engine emissions become more severe every year, and it is difficult to meet the requirements with only combustion improvement techniques. More effective post-processing technology is desired especially for particulate matter (PM), such as carbon soots. Although the use of a ceramic diesel particulate filter (DPF) is now a leading technology for PM removal, the problem exists for the soot removal or regeneration at low temperature, especially at cold start. In the present study, a regeneration of a DPF with collected PM was investigated using the low-temperature atmospheric pressure nonthermal plasma. The method is to use the NO/sub 2/ and radicals induced by the plasma reactor to burn carbon soots deposited on the DPF. First, three types of DPF plasma reactors were made and the performance of the conversion of NO to NO/sub 2/ was evaluated at various conditions. Next, a regeneration experiment was carried out using a barrier-type pulse corona plasma reactor. As a result, it was confirmed that the pressure difference decreased when the plasma was turned on and the regeneration of the DPF (approximately 75% of soot removal) was confirmed when the gas temperature was 250/spl deg/C.     

TCE decomposition by the nonthermal plasma process concerning ozone effect

Dilute trichloroethylene (TCE) and other volatile organic compounds (VOC) in air were decomposed by using the nonthermal plasma process combined with catalysts. To enhance the energy efficiency of the TCE decomposition, some catalysts were tested including their location. It was found that the newly proposed indirect process (VOC cannot be exposed in the plasma region) can also decompose TCE and other VOCs which is due to the ozone dissociation effect. The manganese oxide dissociates ozone to generate oxygen radicals which decompose TCE and other VOCs.     

Effect of water vapor and hydrocarbons in removing NOxby using nonthermal plasma and catalyst

Removal of NO_x in flue gas was investigated by using nonthermal plasma with catalysts. In this experiment, flue gas contained 5%-15% water vapor and hydrocarbons, as well as nitrogen, oxygen, and carbon dioxide. Catalysts tested in this paper were copper- and sodium-coated zeolite (CuZSM-5, NaZSM-5) and a conventional three-way catalyst (Pt-Rh, alumina cordierite). The simulated flue gases had from 0% to 15% water vapor, 70% NO removal was achieved with NaZSM-5 catalyst at 200°C-500°C, with 10% moisture and the power to the reactor turned off. High-temperature removal of NO_x was the result of plasma chemical reactions and adsorption in the catalyst. However, nonthermal plasma degrades the NO_x removal with CuZSM-5 catalyst, when the gas temperature is 300°C or above. When the gas temperature was 100°C, the nonthermal plasma process was enhanced by the combination of nonthermal plasma with any type of catalyst. The catalysts investigated in this paper do not work at lower temperatures by themselves. Adsorption characteristics were also investigated and only NaZSM-5 catalyst showed significant adsorption     

Decomposition of dilute trichloroethylene by nonthermal plasma processing-gas flow rate, catalyst, and ozone effect

Decomposition performance of dilute (100-1000 ppm) trichloroethylene (TCE) contaminated in air by using nonthermal plasma processing was studied to improve the decomposition efficiency. Three kinds of experiments were performed. One is the observation of the decomposition efficiency related to the processing gas flow rate. There exists an optimal gas flow rate for our reactor. The second experiment is the plasma decomposition performance observation related to the catalysts. Some catalysts, such as vanadium oxide (V/sub 2/O/sub 5/) or tungsten oxide (WO/sub 3/) on/in titanium oxide (TiO/sub 2/) pellets, improve decomposition performance. Indirect plasma processing (plasma processed pure air is mixed with TCE contaminated air) suggests the existence of very active oxidation radicals whose lifetime is more than a few minutes but details of them are not yet clear.     

Comparison of reactor performance in the nonthermal plasma chemicalprocessing of hazardous air pollutants

The performance of three different types of plasma reactors such as ferroelectric packed-bed (FPR), pulsed corona (PCR), and silent discharge (SDR) were compared in the decomposition of trichloroethylene (Cl₂C=CHCl, TCE), bromomethane (CH₃Br), and tetrafluoromethane (CF₄). Irrespective of reactors, hazardous air pollutant (HAP) reactivity in dry N₂ decreased in the order: TCE>CH₃Br>CF₄. Similar byproducts were obtained with any of the above reactors, and similar trends were observed in the HAP decomposition rate-retarding effect by water. Only for SDR, TCE decomposition was accelerated by O₂ in the background gas. The most plausible active oxygen species is considered to be the triplet oxygen atom. In the reaction systems where chemically induced decomposition of HAPs can occur, as in the case of TCE, PCR is expected to exceed FPR and SDR in performance. In the cases of CH₃ Br and CF₄, residence time has been the most important factor governing their decomposition rates, and FPR and SDR have shown higher performance than PCR     

NO/sub x/ concentration using adsorption and nonthermal plasma desorption

The gas flow rates for hazardous air pollutant emissions are generally large and their concentrations are low (in parts per million levels). When we try to directly treat the large flow rate and low concentration exhaust gas, the size of the equipment becomes large, resulting in high operating cost. The objective of this study is to convert the exhaust gas with large flow rate and low concentration into the one with small flowrate and high concentration by desorbing the absorbed gas from the absorbent pellets packed inside a barrier-type packed-bed nonthermal plasma reactor. In this paper, we especially focus on the difficulties of treating NO/sub x/. The absorbent pellets were molecular sieve spheres (MS-13X) made of zeolite with 1-nm pore diameter. The plasma desorption was carried out by applying the high voltage to the plasma reactor using any one of AC 60-Hz, AC 20-kHz, or pulse 210-Hz power supplies. We found out that NO/sub x/ could be desorbed effectively in the repeated adsorption and desorption process. Since the surface temperature increased rapidly, the desorption with AC 20 kHz took place not only by the electron impacts but also by the heat addition. In the desorption using the pulse power supply, the concentration rapidly increased and became maximum in a relatively short time. It was effective to close the reactor in the desorption process. It was successful to achieve a nonthermal plasma concentrating desorption of NO/sub x/ as the adsorption/desorption was repeated after more than 12 times.     

不同电解液添加剂对蓄电池循环性能的影响

验证SnSO4作为电解液添加剂的效果,并与使用纳米SiO2与K2SO4的组合添加剂进行对比,通过循环测试验证其实际效果并对其差异进行对比和分析。     

质子交换膜在空气中的热分解动力学

采用非等温TG-DTG技术研究了用于PEMFCs的质子交换膜在空气气氛中的热分解机理及动力学,其线性升温速率分别为5.0、10.0、15.0 K/min和20.0 K/min.采用Kissinger、Flynn-Wall-Ozawa、Achar method、Coats-Redfem方法对非等温动力学数据进行了分析,得到了其热分解的反应机理函数和动力学参数.TG-DTG曲线显示其热分解过程分为二个阶段.第一阶段热分解反应过程受P2(Power law)机理控制,表观活化能为126.1 kJ/mol,指前因子为1.87×107s-1.第二阶段热分解反应过程受F1(化学反应)机理控制,表观活化能为205.5 kJ/mol,指前因子为5.91×1011s-1.     

Behavior of N/sub 2/ and nitrogen oxides in nonthermal plasma chemical processing of hazardous air pollutants

Nonthermal plasma chemical behavior of N/sub 2/-O/sub 2/ mixed gases and nitrogen oxides such as N/sub 2/O, NO, and NO/sub 2/ was investigated to obtain baseline information on the generation of active oxygen species and the formation of inorganic byproducts in the nonthermal plasma chemical processing of hazardous air pollutants (HAPs) with a ferroelectric packed-bed reactor. Ozone concentrations were too low, even in air, to oxidatively decompose 300-1000 ppm of HAPs. The O/sub 2/ concentration in N/sub 2/-O/sub 2/ was the determining factor in the formation of all the nitrogen oxides. N/sub 2/O formation was enhanced with increases in O/sub 2/ concentration and in specific energy density, while a threshold value was observed at around 5% of O/sub 2/ concentration in the formation of NO and NO/sub 2/. Rate-suppressing effect by O/sub 2/, detailed byproduct analyses, and thermochemical data suggest that NO/sub x/ decomposes in its reactions with nitrogen atoms derived from N/sub 2/ dissociation, and that the unimolecular N-O cleavage predominantly occurs for N/sub 2/O. The behavior of nitrogen oxides and their precursors was not affected by hydrogen atoms evolved from hydrogen-rich HAPs such as ethylene and benzene. Halogenated HAPs enhanced NO/sub x/ formation and NO/sub 2/ selectivity. Different additive effects of chlorinated and brominated HAPs were observed in the formation of NO/sub x/ and N/sub 2/O, indicating the involvement of different active oxygen species.     

Low-temperature soot incineration of diesel particulate filter using remote nonthermal plasma induced by a pulsed barrier discharge

Regulations regarding automotive diesel engine emissions become more severe every year, and it is difficult to meet the requirements with only combustion improvement techniques. More effective post-processing technology is desired especially for particulate matter (PM), such as carbon soots. Although the use of a ceramic diesel particulate filter (DPF) is now a leading technology for PM removal, the problem exists for the soot removal or regeneration at low temperature, especially at cold start and engine brake operation. In the present study, a regeneration of a DPF is investigated using indirect or remote nonthermal plasma (NTP) method. The NTP-treated air is injected into exhaust gas, and the NO is oxidized to NO/sub 2/. The induced NO/sub 2/ and activated oxygen species are used to incinerate carbon soot deposited on the DPF. It is confirmed experimentally that the pressure drop decreases when the plasma is turned on and the regeneration of the DPF is possible at the low temperature of 300/spl deg/C. The specific energy density is 22 Wh/m/sup 3/ (= 78 J/L). Although the condition of the NTP is not optimized in the present study, further improvement is required in the energy efficiency.     

微波空气加热技术在化工催化剂活化中的应用

化工工艺中传统的空气加热方式是利用蒸汽换热器、电加热管或电阻炉来加热,电能转化为热能的效率仅有40%左右,且温度不均匀、不稳定。经实践应用,在空气加热工艺中,采用新型的可编程微波加热控制装置,具有热效率高、加热速度快、温度均匀、控制灵活等特点,取得明显的节电效益。     

空调焓差实验室和热平衡实验室异同辨析

文章从试验原理、实验室配置、测试精度、实验室应用等方面详尽论述了目前被广泛采用的空调热平衡实验室和空调焓差实验室的差异,为相关方根据各自的需求选择合适的试验方法提供借鉴。     

Effects of reactor type and voltage properties in methanol reforming with nonthermal plasma

Reactor type and voltage properties affected the reforming behavior of 1% methanol in N/sub 2/ with nonthermal plasma. Methanol conversion increased with voltage frequency for both a ferroelectric packed-bed reactor (FPR) and a silent discharge reactor (SDR), but they showed different sensitivities to frequency change at fixed applied voltages. In the frequency range of 5 Hz-5 kHz, methanol conversion was expressed as a function of reactor energy density irrespective of the reactor type. Regarding the effect of voltage waveform with 50-Hz ac at the same applied voltage levels for FPR and SDR, methanol conversion decreased in the order: triangle>sine>square. H/sub 2/, CO, and CO/sub 2/ were obtained as the major products, and similar product distributions were observed in comparable methanol conversions irrespective of reactor type and the differences in frequency and waveform. Energy conversion efficiency increased to 40%/spl sim/60% at /spl sim/80% of MeOH conversions for FPR and SDR.     

Hydrogen generation from water, methane, and methanol with nonthermal plasma

Hydrogen generation from water, methane, and methanol was investigated with different types of nonthermal plasma reactors under different conditions. With a ferroelectric packed-bed reactor in N/sub 2/, hydrogen gas yield decreased in the order: methanol > methane > water. A similar trend was observed with a silent discharge plasma reactor, but H/sub 2/ yields were much lower with the latter reactor. At fixed specific energy densities, higher H/sub 2/ yields were obtained at higher gas flow rates in the reactions of the above substrates. The initial water concentration was optimized at ca. 2.0% to obtain the highest rate for H/sub 2/ formation. Under the same conditions, H/sub 2/ yield decreased in the order: Ar>N/sub 2/>air/spl ap/O/sub 2/. The ferroelectric packed-bed reactor could be operated continuously for 10 h without any decrease in its performance in the H/sub 2/ generation from water.     

Multimachine stability analysis using vector Lyapunov functions with inertial-centre decomposition

Multimachine power system stability is investigated by means of a new decomposition technique. The power system is decomposed into subsystems using the inertial-centre concept. Individual Lyapunov functions are then obtained for each subsystem. Stability conditions for the overall system are established, taking into account the interconnection characteristics. The least restrictive overall system Lyapunov function is obtained by weighting each subsystem instability is then used to determine the critical clearing time.     

反切及贴壁风技术减轻高温腐蚀实验研究

针对锅炉水冷壁高温腐蚀给安全经济运行带来的危害，对淮坊电厂锅炉高温腐蚀问题，采用反切和贴壁风技术并进行了测试，对减轻高温腐蚀进行了实验研究。结果表明，利用反切和贴壁风技术可有效减轻高温腐蚀。     

氧化镍的热分解法制备及电化学电容器特性

采用水溶液化学沉淀法合成了b-Ni(OH)2粉末,利用热重(TG)、差热重(DTG)及红外光谱(IR)等方法对Ni(OH)2的结构和热分解特性进行了研究。以Ni(OH)2粉末作为前驱体,通过控制其在一定温度下热分解的方法制备了NiO粉末。采用发泡镍作为电极基体,以合成的NiO粉末作为活性物质制作成多孔氧化镍电极,利用循环伏安(CV)及恒电流充放电测试对氧化镍电极在碱性介质中的电化学性能进行了研究和分析。结果表明,NiO粉末材料具有典型的法拉第准电容特性,且其充放电反应的可逆性良好,适合于作为碱性电化学电容器的电极材料。     

氧电极催化剂La0.6Ca0.4CoO3的合成及性能

用溶胶.凝胶法合成了氧电极催化剂La0.6Ca0.4CoO3,通过热重(TG)分析确定了干凝胶的焙烧温度.利用X射线衍射、电化学测试等研究了pH值、柠檬酸用量对催化剂性能的影响.制备La0.6Cao.4C003的最佳工艺条件是:pH=3.0,n(柠檬酸):n(M)=2:1(M为总金属离子).焙烧条件为:700 ℃,2 h.     

Electrically conductor black zirconia ceramic by SPS using graphene oxide

The use of graphene as a component for developing electroconductive ceramic composites is being profusely studied. It is a very promising additive as it has excellent mechanical properties, high electrical and thermal conductivities, it is lightweight and its aspect ratio allows reaching percolation with low contents.In the particular case of zirconia, preparation of black coloured materials remains a challenge while many high added value applications are waiting for a solution. Graphene appears as a candidate for fulfilling all these requirements. In this work, 3Y–TZP/rGO composites were prepared by Spark Plasma Sintering Zirconia-rGO mixtures. Simultaneous sintering and in-situ reduction of graphene oxide opens a very interesting technological route for preparing this type of materials. The influence of graphene content on the electrical, mechanical and optical properties was studied. An rGO content as low as 0,29 vol% allows nanostructured black zirconia to be obtained but it has to be increased up to 1 vol% in order to reach electrical resistivity values <100Ωcm, required for electrodischarge machining.