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1.
A detailed reaction kinetic model consisting of 10 species and 63 reactions is developed to investigate the energy conversion and temperature dependence in an ozone generator using oxygen pulsed discharge. The energy conversion ratios of total electric energy converted into reaction heat, heat carried by gas and heat loss to ambient, namely ηreaction, ηgas and ηloss, are obtained for the first time. The ratio of reaction heat ηreaction decreases substantially with increasing specific energy and inlet gas temperature, which represents how much energy is utilized effectively to synthesize ozone. Correspondingly, ηloss and ηgas increase gradually. ηreaction declines from 55.4% to 27.7% at inlet gas temperature of 298 K when specific energy changes from 0.06 J/cm3 to 0.78 J/cm3. The detailed reaction pathway including the degree of transformation among species for ozone formation is also obtained via kinetics simulation. Meanwhile, sensitivity analysis and rate-of-production analysis for the four most important species O3, O, O(1D) and O2(b1∑) obtained from the reaction pathway are executed to understand quantitatively the temperature dependence of sensitivity coefficient and production rate for each individual reaction. The production rate of ozone via the most important ozone generation reaction O+O2+O2 = > O3+O2 increases linearly with the increase of gas temperature, as well as the destruction rates of ozone via the most important ozone decomposition reactions O3+O3 = > O2+O2+O2 and O3 + O = > O2(b1∑)+O2. 相似文献
2.
Sea Cheon Oh Sang Hyun Sohn Yeong-Koo Yeo Kun Soo Chang 《Korean Journal of Chemical Engineering》1999,16(1):144-149
Two prediction schemes-time series analysis and parameter estimation method-were investigated to predict the formation of
ozone in Seoul, Korea. Moving average method and double exponential smoothing method are applied to the time-series analysis.
Three typical methods, such as extended least squares (ELS), recursive maximum likelihood (RML) and generalized least squares
(GLS), were used to predict ozone formation in a real time parameter estimation. Autoregressive moving average model with
external input (ARMAX) is used as the model of the parameter estimation. To test the performance of the ozone formation prediction
schemes proposed in the present work, the prediction results of ozone formation were compared to the real data. From the comparison
it can be seen that the prediction scheme based on the parameter estimation method gives a reasonable accuracy with limited
prediction horizon. 相似文献
3.
用蒙特卡罗法计算制氢转化炉辐射室温度分布 总被引:2,自引:0,他引:2
采用蒙特卡罗方法对制氢转化炉辐射室、炉管以及烟气的温度进行计算。和实际测量结果比较表明 ,模拟计算结果较好地反映了辐射室的温度分布情况。通过计算炉管温度分布 ,有助于研究制氢转化炉炉管弯曲的机理 相似文献
4.
Siemens made the first ozone generation system by corona discharge about hundred and fifty years ago. At present mainly two types of atmospheric pressure electrical discharges - corona discharge and dielectric barrier discharge are used for production of ozone. Another type of discharge, which can be used for this purpose, is multineedle to plate electrical discharge enhanced by the gas flow. Contrary to the conventional arrangement when the gas is flowing around the needles we studied the discharge in which the gas was pumped through the needles. Results of studies of ozone and nitrogen oxides production by DC electrical discharge in air at atmospheric pressure with a single hollow needle to plate electrode configuration enhanced by the flow of air through the needle for both polarities of the needle, different airflow rates and currents are presented in this paper. 相似文献
5.
A semi-empirical equation is derived to provide a correlation between the ozone generation rate of a negative wire-to-plate corona discharge in both dry and humid air and a series of design/operating parameters. A basic correlation is first derived by applying dimensional analysis on negative wire-to-plate corona discharge in dry air. Further development on the basic correlation is carried out by integrating the influence of humidity. The derived equation is validated by previously reported experimental data and numerical model. The new semi-empirical equation is comprehensive and useful in guiding the design/operation of indoor corona devices under actual ambient operating conditions. 相似文献
6.
Dae Hun Chung Jae Bok Yang Dong Sun Noh Won Bae Kim 《Korean Journal of Chemical Engineering》1999,16(4):489-493
High temperature preheated and diluted air combustion has been confirmed as the technology, mainly applied to industrial furnaces
and kilns, for realizing higher thermal efficiency and lower emissions. The purpose of this study was to investigate fundamental
aspects of the above-mentioned combustion experimentally and to compare with those in ordinary hydrocarbon combustion with
room temperature air. The test items were exhaust gas components of CO, NOx, flame shape and radical components of CH, OH and C2, which we measured with gas analyser, camera and ICCD (Intensified Charged-Coupled Device) camera. Many phenomena, as a result,
which appeared in the combustion with the oxidizer, low oxygen concentration and extremely high temperature air, such as expansion
of the flammable limits, increased flame propagation speed, looked very strange in comparison with those in existing combustion
technology. We confirmed that such extraordinary phenomena were believable through a hot-test experiment. 相似文献
7.
Ozone generation in both positive and negative corona discharges DC corona, both operated in glow regime, feed by dry CO2 has been studied. Higher ozone concentrations were observed in negative corona discharges. Ozone formation was found to be strongly dependent upon both the flow rate of the gas and on the radius of the outer electrode. The physical characteristics of the discharge were monitored through measurement of the discharge current. Small increases in the gas flow rate were observed to cause a significant increase in the discharge current of a negative corona discharge but little/no effect was observed in positive corona. 相似文献
8.
Ozone generation in both positive and negative corona discharges DC corona, both operated in glow regime, feed by dry CO2 has been studied. Higher ozone concentrations were observed in negative corona discharges. Ozone formation was found to be strongly dependent upon both the flow rate of the gas and on the radius of the outer electrode. The physical characteristics of the discharge were monitored through measurement of the discharge current. Small increases in the gas flow rate were observed to cause a significant increase in the discharge current of a negative corona discharge but little/no effect was observed in positive corona. 相似文献
9.
Particulate collection at high temperature and high pressure (HTHP) is important in an advanced coal power generation system
not only to improve the thermal efficiency of the system, but also to prevent the gas turbine from erosion and to meet the
emission limits of the effluent gas. The specifications for particulate collection in those systems such as Integrated Gasification
Combined Cycle (IGCC) and Pressurized Fluidized Bed Combustion (PFBC) require absolutely high collection efficiency and reliability.
Advanced cyclone, granular bed filter, electrostatic precipitator, and ceramic filter have been developed for particulate
collection in the advanced coal power generation system. However, rigid ceramic filters and granular bed filters among them
show the best potential. The problems experienced of these systems on performance, materials, and mechanical design were investigated.
Ceramic candle filters have the best potential for IGCC at this moment because they have nearly the highest efficiency compared
with other filtering systems and have accumulated many reliable design data from many field experiences. The purpose of this
study was to investigate the efficiency of ceramic filters and stability of material against high temperature and longterm
operation condition by applying fly ash on the surface of the filter and relation of pressure drop and dust cake thickness.
Experimental conditions were 50 hours at 450 °C, 650 °C and 850 °C. 相似文献
10.
Formation of bromate is of a great concern whenever ozone-based technologies are used for treating highly bromide-containing water ever since bromate was classified as a potential carcinogen. Saudi Arabian groundwater is coincidentally high in bromide content, and the potential of forming bromate during the treatment of such water is high. This study investigated the extent of bromate formation under different treatment conditions of ozone-based Advanced Oxidation Processes (AOPs) when used for the treatment of phenol-contaminated water. The results of the study showed that continuous ozonation at a rate of 1 L/min has completely removed 50 ppm of phenol from contaminated water in less than 5 min. However, as high as 8.85 ppm of bromate (BrO3−) was detected when treating the water which has high concentration of bromide ion (5 ppm). Results also showed that by adjusting the pH to 6 and adding ammonia (NH3) at a dosage of 1.5 ppm, bromate formation was diminished drastically to non-detected levels. 相似文献
11.
《Ceramics International》2020,46(5):6154-6159
Ca2YZr2Al3O12:Bi3+,Eu3+ phosphors were elaborated by a traditional solid-state reaction method. The luminescence of Ca2YZr2Al3O12:Bi3+ samples, energy transfer from Bi3+ to Eu3+, and the temperature sensing properties of Ca2YZr2Al3O12:Bi3+,Eu3+ samples have been systematically researched. Under the excitation of ultraviolet light, Bi3+ single doped phosphors give 313 and 392 nm emission bands, which origin from the substitutions of Bi3+ instead of Ca2+ and Y3+ sites, respectively. And the color-adjustable emission from blue to red were observed by increasing Eu3+ content in Ca2YZr2Al3O12:Bi3+,Eu3+ samples. Relying on different temperature dependent variation tendency, the fluorescence intensity ratio (FIR) values present outstanding temperature sensing properties. The absolute and relative sensitivity can be up to 0.826 %K-1 and 0.664 %K-1, respectively. All above results suggest that Ca2YZr2Al3O12:Bi3+,Eu3+ phosphor is a potential alternative for optical thermometer. 相似文献
12.
The effects of pH and temperature of a stannate bath on the quality of stannate chemical conversion coatings formed on AZ91 D magnesium alloy by using the potentiostatic polarization technique at E = −1.1 V were investigated in order to improve uniformity and corrosion protection performance of the coating films. It was found that the uniformity and corrosion resistance of coating films deposited by potentiostatic polarization were closely associated with pH and temperature of the coating bath. The pH and temperature to obtain the best coating film were investigated as a function of corrosion protection performance evaluated by curves of potentiodynamic anodic polarization conducted in borate buffer solution. Scanning electron microscope observation and electrochemical corrosion tests of the stannate-coated samples confirmed significant improvement in uniformity and corrosion resistivity of coating films deposited by the potentiostatic technique by modifying the pH and temperature of the coating bath. It was also found that uniformity and corrosion resistivity of the coating films deposited by the potentiostatic technique were considerably improved compared to those of coatings deposited by the simple immersion method at the best conditions of pH and temperature of the coating bath. 相似文献
13.
Ozone formation from a propene-nitrogen oxide-wet air mixture was modeled and simulated by using a detailed reaction model
to characterize ozone formation in air pollution. Effects of reaction parameters such as light intensity, initial concentrations
of propene and nitrogen oxides, temperature and humidity were investigated. The loss reactions of N2O5 by H2O were incorporated in the model developed in the present study. Results of simulations showed good agreement with smog-chamber
experimental data. From the results of simulations it was found that the maximum ozone concentration was little affected by
humidity. The model proposed in the present study can be used to predict the amount of ozone formation successfully. 相似文献
14.
A solar drier with and without air recycling (Methods I and II) along with a sun drying system (Method III) were used to reduce the moisture content of pistachio from 40 to ~5% (wet basis) at similar weight conditions. Although the ΔT’s of ambient air in Methods I and II reached, respectively, to 18 and 14°C, it did not increase more than 2°C in Method III. The drying air of Method I obtained ~55% more enthalpy from its solar collectors and transferred ~35% more heating energy to the product than the one in Method II. Consequently it’s thermal and pickup efficiencies became, respectively, 40 and 80% more than Method II. Although the highest exergy efficiencies of Methods I and II were equal to each other (~95%), the maximum exergy loss of Method I was higher than Method II due to its higher air temperature and pressure loss (because of continuous air circulation). Although its energy utilization ratio and drying rate were, respectively, 30% more than Method II and 20% higher than Method III, its drying time was 20 and 30% less than the ones in Methods II and III. Overall, the pistachio dried with Method I used much less energy than those dried with other methods and had a higher quality than those dried with commercial driers due to drying temperature <50°C. 相似文献
15.
交流伺服电机制动能量的回收利用、机筒加热散发热量的回收利用,低能耗高性能机筒加热装置的应用,提高了电能的利用率.蓄能器高速驱动,减少了电机低负载运行的时间,增加了电机高功率因数高效率运转的时间,减少了电能的损耗,同时大幅度减少了系统的装载率.提高注塑机电能的利用率是必不可少的一项节能技术. 相似文献
16.
This paper describes the influence of gas pressure on the conversion of O2 to O3 and the ozone production efficiency in a multichannel dielectric barrier discharge (DBD) reactor utilizing positive and negative pulses. Results show that conversion of O2 to O3 is continuously enhanced by the increase of gas pressure (0.1–0.24 MPa) while the rising speed of oxygen conversion with the increasing gas pressure at fixed specific input energy is reduced above 0.15 MPa. The maximum ozone generation efficiency is increased with increasing gas pressure (0–0.2 MPa) while positive pulse exhibits higher energy efficiency. The maximum ozone generation efficiency is suppressed with further increase of gas pressure (0.2–0.24 MPa) while no significant difference in ozone generation efficiency is observed for two unipolar pulse modes. Results also show that 0.2 MPa is the optimal working gas pressure to obtain the maximum ozone generation efficiency and increasing gas pressure would lead to remarkable increase of ozone generation efficiency for ozone production at high energy densities in multichannel DBD. 相似文献
17.
化工过程分析与合成是化工类实践性非常强的专业基础课。在过程工业中,能量是通过换热网络进行传递的,换热网络设计是此课程教学过程中的重要内容之一。本文应用夹点技术,采用Aspen Energy Analyzer软件对简单的换热网络进行分析、综合和优化,使学生更加容易理解和掌握夹点的基础理论,同时使学生熟悉该软件的使用,为后续化工设计和毕业设计的相关换热网络研究打下基础,也可为日后的科研开发、工程设计和生产管理提供了一种有力的技术手段。 相似文献
18.
《Ceramics International》2016,42(3):4238-4245
High optical quality Y2O3 transparent ceramics with fine grain size were successfully fabricated by air pre-sintering at various temperature ranging from 1500 to 1600 °C combined with a post-hot-isostatic pressing (HIP) treatment using co-precipitated powders as the starting material. The fully dense Y2O3 transparent ceramic with highest transparency was obtained by pre-sintered at 1550 °C for 4 h in air and post-HIPed at 1600 °C for 3 h (the pressure of HIP 200 MPa), and it had fine microstructure and the average grain size was 0.96 μm. In addition, the in-line transmittance of the ceramic reached 81.7% at 1064 nm (1 mm thickness). By this approach, the transparent Y2O3 ceramics with fine grain size (<1.6 μm) were elaborated without any sintering aid. 相似文献
19.
In order to enhance the conversion of shape-selective methylation of 2-methylnaphthalene with HZSM-5 for producing 2,6-dimethylnaphthalene, an important precursor of high performance polyester, effect of reaction method was investigated. It was found that an unsteady-state reaction method with adsorption at a low temperature and subsequent flush at somewhat elevated temperature was very effective for enhancing the conversion drastically. This new reaction method, named low temperature adsorption and flush (LTAF) method, made it possible to increase the conversion up to more than 70% without losing shape-selectivity, whereas, by the conventional steady-state reaction method, the conversion remained at 10-20% level due to restricted diffusion of naphthalene-ring compounds in the HZSM-5 pore which was essential for the shape-selectivity. By LTAF method, the methylation can be performed in the range of temperature lower than that required for steady-state reaction, and the methanol conversion as a side reaction was effectively suppressed. 相似文献
20.
Understanding the effect of drying process parameters on food quality is helpful in process optimization and control. The objective of this work is to understand the effect of mild and harsh effective moisture diffusivity (Deff), varied by air temperature and velocity, of drying processes on the physical and sensory quality of flat food products. Pumpkin seeds were selected as a food representative. It was found that increments of air temperature and velocity resulted in increased Deff and brown color on seed hull surfaces and embryos, but decreased hardness of seed embryos. Changes in taste and aroma of seed embryos were able to be sensed. Indicating that Deff is related to seed physical quality. Similar phenomena occurred with both tray and fluidized bed drying. Air temperature, velocity, and Deff should be controlled to ensure the best dried flat food products. Mild drying conditions are potentially preferred for good physical and sensory quality. 相似文献