摘要:

A class of cement based on a new cementitous phase Alinite has been produced by clinkering at 1150°C. An important empirical correlation between free lime of Alinite cement clinker and weight percent of CaCl2content in raw mix in various temperatures has been established for the purpose of clinker mix design. The optimum CaCl2addition to the raw mix is found to be 5-6% by weight. Alinite clinkers which are very friable can be produced at 1150° C. In addition to the substantial energy saving, these cements have also been found to be relatively insensitive to various impurities in the raw mix. This low temperature clinkering route thus appears to be a promising method of converting industrial wastes into hydraulic setting cements.

ISSN:0098-6445    

DOI:10.1080/00986449908912746

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Spindle-shape goethite (a-FeOOH) extremely fine particles were produced by air oxidation of an aqueous suspension consisting of a mixture of FeS04and Na2CO3at 30-40°C, using a standard-type bubble column. The time dependences of the fractional oxidation of total Fc(II7rpar; were measured under various combinations of experimental conditions. The shape and size (i.e., major and minor axes) of prepared a-FeOOH particles were observed with the aid of transmission electron microscopy. From such measurements and observations, the mechanism of spindle-shape a-FeOOH particle formation was deduced; the total number of a-FeOOH nuclei is fixed in the early stage of the oxidation reaction, and subsequently, only the particle growth tends to take place until leading to the final size, depending on the reaction condition, i.e., reaction rate.

ISSN:0098-6445    

DOI:10.1080/00986449908912747

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

An analysis of the solidification rates of binary mixture melts flowing as a thin film on a cold surface, useful in the separation or purification of eutectic mixtures, is presented. The analysis which incorporates the hydrodynamics of the falling film and the convective heat transfer at the melt/crystal interface was used to determine the average crystallization velocity. The effect of parameters such as Stefan number (subcooling), initial superheat and the melt loading rate on the average crystallization velocity was examined. Experiments were performed using three different binary organic mixtures at subeutectic compositions. The results of the theoretical and experimental studies showed good agreement validating the model.

ISSN:0098-6445    

DOI:10.1080/00986449908912748

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Coked catalyst in fixed bed reactors is regenerated by passing hot air mixed with a non-reacting diluent (like steam(. The concentration of oxygen in the regenerating stream is increased from the beginning of the regeneration following a so called regeneration protocol, in order to minimize the regeneration time but still maintaining the maximum temperature within the reactor below permissible level. In this paper, we have modelled the low temperature regeneration in fixed bed reactors and have suggested general regeneration protocols, suitable for wide range of process conditions

ISSN:0098-6445    

DOI:10.1080/00986449908912749

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Pressure drops were determined in fluid flow through SMX Suizer static mixer of different sizes. In order to investigate a large range of Reynolds number, the experiments were performed with fluids of different viscosities. Pressure drops measurements in static mixer considered as a porous medium, are analysed with a capillary model for the determination of the geometric parameters of static mixers: pore diameter and tortuosity. These parameters allow the expression of pressure drops in terms of friction factor,fcas a function of pore Reynolds number, RepA universal equation is obtained for the friction factor:fc=16/Rep+,0.194 which covers both viscous and inertial flow regimes.

ISSN:0098-6445    

DOI:10.1080/00986449908912750

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The cylindrically-shaped outer hair cell functions as an active support beam in the inner ear. We develop a model for electromechanical transduction when the cell supports a load. The model is an extension of Jerry and Dutta [Chemical Engineering Communications, 166 (1998), 81 -110]. We use our model to simulate a “tensile test” on the cell, similar to that used to measure the elastic modulus for plastic, metal and ceramic specimens. Our work demonstrates the importance of accurate control of cell volume or intracellular pressure during experiments, and also suggests that voltage clamping may not be necessary when measuring the elastic properties of the cell. A plot of the polyelectrolyte-associated charge (that is moved across the wall) vs. the load reveals a charge reversal effect: at a particular value of the load, the direction of charge movement changes. The effect can be explained using our model.

ISSN:0098-6445    

DOI:10.1080/00986449908912751

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The effect of pressure on the measured bimolecular rate constant of the Diels-Alder reaction between maleic anhydride and isoprene was investigated in supercritical CO2and sub-critical propane. The reaction was carried out at 35°C in CO2and 80°C in propane. Measured bimolecular rate constants are also compared to predictions from the thermodynamic pressure effect using transilion state theory and the Peng-Robinson equation of state. The rate constants in supercritical C02agreed closely with the thermodynamic pressure effect predictions over the entire pressure range. Furthermore, the mole fraction based rate constants were found to vary linearly with the density of the solution. The rate constants in the sub-critical propane solvent significantly diverged from the thermodynamic pressure effect predictions and were found to deviate from this linear density dependence at the lower pressures studied. The results are interpreted in the context of local reactant concentrations about the reacting maleic anhydride and solvent-solute and cosolvent-solute interactions.

ISSN:0098-6445    

DOI:10.1080/00986449908912752

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Present inventory of Hanford single shell tank waste is about 180,000 tons. More than 70%by weight of the tank waste are non-radioactive sodium nitrate. The paper presents an entirely different approach to pretreatment of Hanford radioactive waste stored in underground tanks. Instead of removing radionuclides,137Cs in this case, from the bulk of the waste, this process selectively recovers the non-radioactive sodium salts from the waste by crystallization. It opens up a possible new way of looking at waste pretreatment. The feasibility teat has been done at the facility of Westinghouse Hanford Company. The result shows a potential of reclaim sodium nitrate with a total activity of less than 60 pCi/g

ISSN:0098-6445    

DOI:10.1080/00986449908912753

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

A closed-loop analysis is presented for a turbulent multiphase fluid mechanical model of flow along a shallow channel, which is capable of accurately predicting free surface elevations at any point within the computational domain. It is shown that simulations based on a finite difference method and the mixing length hypothesis, effectively account for turbulent effects, with good agreement between theoretical predictions and recently performed experiments. The proposed model has many applications in everyday engineering.

ISSN:0098-6445    

DOI:10.1080/00986449908912754

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The application of the BET model to determine ionic activity coefficients of the aqueous nitric acid system is investigated. BET parameters are determined from published data and the model is applied to predict activity coefficients up to very high concentrations. It is shown that the BET model can be used on systems where the reference state is not a regular solid crystal and which exhibit strong hydrogen bonding. Additionally, it is demonstrated that the BET model shows a good potential for application at concentrations an order of magnitude higher than previously investigated. It is revealed that the most important parameter in the BET model at very high concentrations is the choice of a reference state. The focus of this ongoing study is outlined.

ISSN:0098-6445    

DOI:10.1080/00986449908912755

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor