氧化钴高温光谱选择性吸收涂层

本文讨论了氧化钴高温光谱选择性吸收涂层的制备方法、性能及组成。其太阳光谱吸收率为0.89-0.92,红外发射率为0.15-0.20。涂层与底板结合牢固,耐温在600℃以上。     

DDS—一种新型的频率合成技术（一）

ＤＤＳ（直接式数字频率合成）是八十年代发展起来的新型频率合成技术。本篇介绍了它的基本工作原理、线路构成和性能特点。以下各篇将继续从ＤＤＳ－ＰＬＬ频合器、电路设计与实现、ＤＤＳ频合器性能分析、影响ＤＤＳ频合器指标的主要因素以及设计ＤＤＳ频合器须注意事项等方面进行阐述。     

分子筛疏水改性对CO2吸收强化的影响

Two methods of the modification of zeolite were employed:framework element modification and surface coating,and the influence of the zeolites before and after modification on the CO₂ absorption was investigated.It was found that although hydrophobicity of zeolite could be obtained by means of the surficial organic coating in the method of surface coating modification,partial channel of zeolite would be plugged,as a result,leading to the surface area reducing greatly.Distinctively,the framework element modification method could maintain not only complete lattice structure and adsorption capability of zeolite,but would also obtain a good hydrophobic property.Consequently,significant enhancement on gas absorption by this modified zeolite was achieved and up to a maxi-mum enhancement factor of 2.62.This shows that the solid particles with good enhancement role to gas absorption need not only good adsorptive capability but also certain hydrophobicity.An unsteady heterogeneous model was employed to predict enhancement factor and the calculated results agree well with the experimental data.     

活性炭粒子对K2CO3溶液中CO2化学吸收的强化

The enhancement of chemical absorption of CO2 by K2CO3/H2O absorbents in the presence of activated carbon （AC） particles was investigated. The results show that the gas absorption rates can be enhanced significantly in the presence of AC particles, and the maximum enhancement factor 3.7 was observed at low stirring intensities. The enhancement factor increased rapidly with the solid loading during the initial period of absorption and then be- came mild gradually to a maximum value. Both the liquid-solid contact area and the probability of solid particles residing at the gas-liquid interface decreased with the increase of the particle size, leading to a negative effect on the enhancement of mass transfer. The influence of the particles on gas absorption decreased with the reaction rate. The stirring speed changed the interfacial coverage and mass transfer rate on the liquid side and consequently affected the mass transfer between the gas and liquid phases; the enhancement factor decreased with the stirring intensity. A heterogeneous two-zone model was proposed for predicting the enhancement factor and the calculated results agreed well with the experimental data.     

第三分散相液滴增强气体吸收的一维非稳态非均相传质模型

A model for one-dimensional unsteady heterogeneous mass transfer was developed based on Danckwerts’ surface renewal theory in order to describe the mass transfer enhancement of absorption process for a slightly soluble gas in a gas-liquid-liquid system. The model accounts for the mass transfer resistance within the dispersed phase and the effect of emulsion viscosity on mass transfer. An analytical solution for enhancement factor was obtained by Laplace domain transformation. The absorption rates of carbon dioxide in the dodecane-in-water and castor oil-in-water systems were measured in a thermostatic reactor, and the enhancement factors were calculated at different volume fractions of dispersed phase and stirrer speeds. The model predictions agree well with the experi-mental data.     

微细固体颗粒对CO2吸收速率的影响

利用恒温反应器研究了颗粒性质对CO2在浆液中吸收的影响。实验选用三种溶剂：水、环己烷和大豆油,在其中分别加入不同性质的固体颗粒：活性炭、活性氧化铝和硅胶作为研究体系。结果发现,水溶液中只有活性炭表现出了明显的吸收强化效果;而在环己烷溶液中则相反,活性炭失去了强化作用,Al2O3和硅胶却对吸收起到了促进效果。由此说明能够具有吸收强化效果的颗粒需要具有两方面的性质：憎溶剂性及对溶质较高的吸附容量。同时,根据实验结果,增强因子随颗粒浓度的增加会渐进地趋于一个恒定值;搅拌速度提高强化因子会随之降低。表明强化因子与颗粒在气液界面的覆盖率有关,搅拌速度提高界面覆盖率下降。     

活性炭粒子对K2CO3溶液中CO2化学吸收的强化

The enhancement of chemical absorption of CO2 by K2CO3/H2O absorbents in the presence of activated carbon (AC) particles was investigated. The results show that the gas absorption rates can be enhanced significantly in the presence of AC particles,and the maximum enhancement factor 3.7 was observed at low stirring intensities.The enhancement factor increased rapidly with the solid loading during the initial period of absorption and then became mild gradually to a maximum value. Both the liquid-solid contact area and the probability of solid particles residing at the gas-liquid interface decreased with the increase of the particle size,leading to a negative effect on the enhancement of mass transfer. The influence of the particles on gas absorption decreased with the reaction rate. The stirring speed changed the interfacial coverage and mass transfer rate on the liquid side and consequently affected the mass transfer between the gas and liquid phases; the enhancement factor decreased with the stirring intensity. A heterogeneous two-zone model was proposed for predicting the enhancement factor and the calculated results agreed well with the experimental data.     

正十二烷-水乳液吸收丙烷的传质增强作用(英文)

A one-dimensional unsteady heterogeneous parallel mass transfer (ODUHPMT) model was developed for the absorption enhancement of volatile organic compounds (VOC) by the dispersed droplets. An analytical solution for enhancement factor was obtained based on surface renewal theory and the Laplace domain transformation. The absorption rate of propane into water at dif-ferent stirring speeds with the added micro dodecane droplets was investigated experimentally in a thermostatic stirred tank. The mass transfer flux across the gas-liquid interface and the enhancement factor were measured. The results showed that the dodecane has an obvious enhancement effect on propane absorption into water, the maximum enhancement factor reached 11. The enhance-ment factor increased with increasing dodecane volume fraction and decreased with increasing stirring speed. The experiment data agreed well with the model predictions and showed high prediction accuracy of ODUHPMT model.     

DDS—一种新型的频率合成技术（二）

ＤＤＳ的基本原理已在上一篇文章中作了介绍。本篇叙述利用ＤＤＳ技术设计的一些实用电路以及在通信产品中的应用。着重分析了ＤＤＳ／ＰＬＬ频率合成器的构成及其性能，为频率合成提供了一条新的途径。     

TiO2浆液中气体的吸收强化

讨论在CO2／H2O吸收体系中加入TiO2微细颗粒所产生的效果及其吸收强化机理．研究表明，随TiO2在液体中含量增加，增强因子不断增加，但颗粒浓度达一定值后，增强因子不再继续提高．TiO2含量对搅拌转速及颗粒直径的影响表现出了与原结论不一致的现象2在很低转速下，TiO2对吸收几乎没有强化作用，而2μm的TiO2颗粒所体现出来的增强因子反倒小于20μm的颗粒增强作用．这些现象表明，不同的颗粒所引起的强化作用不仅要考虑颗粒的吸附作用，还要考虑颗粒的动力学效应，仅凭shuttle机理不能给出合理的解释．