Crystal violet adsorption on industrial waste (hog fuel ash): equilibrium kinetics with process optimization by response surface modeling

Clean Technologies and Environmental Policy - The adsorptive removal of crystal violet from aqueous solution utilizing hog fuel ash, an industrial solid waste, available abundantly is reported in...     

Excitation of acoustic vibrations upon combustion of droplets of liquid fuel at supercritical pressure

Theoretical investigation of the excitation of acoustic vibrations upon combustion of liquid fuel droplets at a supercritical pressure of a gaseous mixture is carried out. The droplets are assumed to be spherical and mono-dispersed. The combustion is assumed to run in the diffusion regime. The binary diffusion coefficients are taken equal and independent of the concentration of the components of the gaseous mixture. The Lewis number is assumed to be unity. The flow is considered to be one-dimensional; the mixing in the transverse direction is assumed to be complete, with no mixing in the longitudinal direction. The rate of combustion at supercritical pressure of the gaseous mixture is calculated on the basis of the modified quasi-stationary theory. Expressions for the frequency and excitation increment of acoustic vibrations are obtained in this paper; the properties of the fuel and the oxidizer are explicitly taken into account.     

The combustion of a system of liquid fuel drops

We examine the combustion of drops in a system of solitary drops. It is established that the rate of combustion for the system varies with a change in the distance between the drops.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 16, No. 4, pp. 617–621, April, 1969.     

乏燃料贮存格架在组件跌落事故中的冲击分析

为解决乏燃料贮存格架在组件跌落事故中的冲击分析问题,对ANSYSLS-DYNA程序在弹塑性条件下的冲击分析功能进行开发,并运用于300 MW压水堆核电厂乏燃料贮存格架受乏燃料组件撞击的仿真分析中,采用应变失效和变形失效的方法对乏燃料贮存格架进行安全评定,证明现有的设计满足安全要求。所应用的弹塑性冲击分析方法,以及对乏燃料贮存格架评定的方法同样适用于其它核电设备。     

Environmentally friendly catalytic combustion of gaseous fuel to heat greenhouses

Data on the study of thermally stable manganese oxide catalysts for deep oxidation of lean CH₄ and propane–butane mixtures in air into CO₂ are presented in the paper. New approaches to the synthesis of polyoxide catalysts based on Mn, modified with rare earth elements (La, Ce) and alkaline earth elements (Ba, Sr) when its supporting from nitrate solutions onto the alumina granules stabilized with 2 % Ce were used in the preparation of catalysts. Polyoxide thermally stable (up to 1473 K) high-performance Mn-containing catalyst for deep oxidation of CH₄ and propane–butane in gas-air mixture was developed. Prototype of the catalytic heat generator for environmentally friendly burning of methane and propane–butane mixture was created. Experienced tests of the catalytic heat generator for heating of greenhouses were performed and carbon dioxide fertilizing of plants by combustion products of propane–butane mixture was carried out.     

Design strategies for response surface models for the study of supersonic combustion

An application of a classical design approach to an experiment involving the study of supersonic combustion is described in this paper. The case study described is that of an experiment whose objective is to create response surfaces of the mean and variance of several flow parameters as a function of location within a supersonic jet flow field. The approach demonstrated in this paper involves the use of a classic response surface methodology design in a unique manner. Additionally a unique application involving the sub‐sampling and replication strategies is developed in a similar manner to those of robust parameter design. The sub‐sampling and replication techniques allow for the ability to systematically account for the precision in mean and variance models of the output response variables. The final design prescribed met the experimental objectives of the project by creating the ability to fit response surfaces and allowing for the experimenters to understand the relative precision of their estimates based on the final sub‐sampling and replication techniques. Results from one section of the region of interest are used to illustrate two different modeling approaches. The performance of both modeling approaches in prediction of new data is illustrated. The conclusions also include a discussion of the future work that will follow. Copyright © 2008 John Wiley & Sons, Ltd.     

The equilibrium shape of a charged drop in parallel electrostatic and aerodynamic fields

An analytical expression describing equilibrium spheroidal deformation of a charged drop exposed to parallel aerodynamic and electrostatic fields is derived based on the principle of minimum potential energy of a closed system in the equilibrium state. The expression relates eccentricity of the spheroid to the electrostatic field strength and the streamlining flow velocity.     

Convenient conversion of calcium carbonate to hydroxyapatite at ambient pressure

The synthesis of hydroxyapatite is described starting from calcium carbonate and monoammoniumphosphate in stoichiometric amounts. The novel aspect concerns the reaction conditions which are simple mixing in water at ambient pressure and 60 °C. The calcium carbonate solid phase slowly evolves CO₂ gas and buffers the solution at a pH value of 8.05 where hydroxyapatite precipitates. The main advantages of this reaction pathway are the absence of nitrate salts, the availability of the starting materials and the purity of the final product.     

Calculation of plane porous radiators with surface combustion

Results of theoretical and experimental studies of porous radiators for heating various materials are compared.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 42, No. 4, pp. 627–633, April, 1982.     

The equilibrium shape of a liquid drop in mutually perpendicular electrostatic and hydrodynamic fields

An analysis of the balance of pressures on the surface of a drop of an ideal incompressible liquid, exposed to a homogeneous electrostatic field and streamlined by a laminar flow of an ideal incompressible fluid perpendicular to the field, shows that, in the approximation linear with respect to the deformation amplitude, the equilibrium drop shape represents a triaxial ellipsoid.     

Predicting pressure drop in venturi scrubbers with artificial neural networks

In this study a new approach based on artificial neural networks (ANNs) has been used to predict pressure drop in venturi scrubbers. The main parameters affecting the pressure drop are mainly the gas velocity in the throat of venturi scrubber (V(g)(th)), liquid to gas flow rate ratio (L/G), and axial distance of the venturi scrubber (z). Three sets of experimental data from five different venturi scrubbers have been applied to design three independent ANNs. Comparing the results of these ANNs and the calculated results from available models shows that the results of ANNs have a better agreement with experimental data.     

Bed pressure drop of a bubbling fluidized-bed with overflow solid discharge

The pressure drop of a bubbling fluidized-bed that employed an in-bed inlet and an overflow outlet for continuous flow of solid particles was investigated with variation in the particle size and density, the solid flow rate and the gas velocity. The bed pressure drop decreased with increasing the gas velocity, but increased with the solid flow rate. The characteristics in lifting the solid particles vertically to the level of the overflow outlet by bubbles appeared different from the ones of particle entrainment and bed expansion. Regardless of size and density of particles, bed height in minimum fluidizing condition (pressure head by solid bed weight, H_mf,f) decreased with increasing the volume flow rate of bubble but increased with the mass flow rate of solid particles. The nominal vertical height from H_mf,f to the level of the overflow outlet that the particles should overcome in the course of discharging out of the fluidized-bed with the aid of bubbles increased as either the volume flow rate of bubble increased or the mass flow rate of solid particles decreased. The power consumed while bubbles lifted particles to be discharged appeared to be same at the fixed volume flow rate of bubble. A correlation was proposed successful even for predicting the bed pressure drop of the recycle chamber of the loop seal and the external solid circulation rate in the circulating fluidized-bed system.     

预热燃料在无焰燃烧模式下的NO_x排放特性

采用燃料预热燃烧工艺,在30 kW煤粉无焰燃烧实验台上探索高温预热燃料的无焰燃烧可行性,及其燃烧和NO_x排放特性。结果表明:高挥发分的神木烟煤和低挥发分的气化细粉灰均能在该实验系统上实现稳定的无焰燃烧;煤粉经过预热过程,部分挥发份析出,部分焦炭气化,产生高温煤气和煤焦;高温预热燃料(煤焦和煤气)经燃料喷口进入燃烧室,进行分级燃烧,有效降低燃烧温度的峰值,燃烧温度分布更均匀,燃烧温度波动均低于10%;NO_x主要来源于焦炭氮,在燃烧室的下游被焦炭的异相反应所还原;对于神木烟煤和气化细粉灰,NO_x排放分别为90.4、96.7 mg/m~3(O_2体积分数为6%时,@6%O_2)。     

常压干燥制备高弹性气凝胶

以甲基三甲氧基硅烷(MTMS)为硅源,水为溶剂,醋酸和氨水为酸碱催化剂,采用酸碱两步法,六甲基二硅胺烷(HMDS)作为表面修饰剂,常压干燥制备了半透明、块体气凝胶.得到的气凝胶疏水性很好(接触角为158°),具有很好的弹性性能,良好的保温隔热性能(热导率为0.031W/(m·K)).用扫描电镜、比表面积与孔径分析仪、力...     

Application of response surface methodology to optimize high active Cu-Zn-Al mixed metal oxide fabricated via microwave-assisted solution combustion method

The present work deals with evaluation of decisive parameters on performance and structure of Cu_0.4Zn_0.6Al₂O₄ catalyst. In this respect, the experiments were designed by the response surface methodology (RSM), considering the main parameters: the amounts of urea and ammonium acetate and the activity were assessed in esterification reaction. The results of statistical analysis showed that the proposed second-order equation is highly compatible with experimental data and the interaction between the ratios of both fuel types is highly effective as well independent variables. The catalyst synthesized with the fuel content higher than the stoichiometric ratio (67% urea and 45% ammonium acetate) has the highest catalytic activity in the esterification reaction, where the efficiency of about 98.2% is obtained in the esterification reaction under the conditions of 180 °C, methanol to oleic acid molar ratio of 9, 3 wt% of catalyst and 6 h of reaction time. The sample fabricated with 67% urea and 45% ammonium acetate as fuel (more than stoichiometric ratio) presented the highest activity that could convert 98.2% of oleic acid to ester. Characterization of the catalysts showed that the particle size reduced from about 18 nm for the catalyst synthesized with single fuel to 12 nm for that synthesized at fuel rich condition. Moreover, the unit cell size was meaningfully changed by using combined fuel that can be related to incorporation of simultaneous Zn and Cu for preparation of aluminate structure. As well as use of combination urea and ammonium acetate led to increase the textural properties (surface area from 4.76 m²·g⁻¹ to 8.39 m²·g⁻¹ and mean pore size from 2.1 nm to 8.9 nm). The results can confirm formation of dopant structure of Zn/CuAl₂O₄ in which a few amount of single phase was detected.     

The rate dependent response of a titanium alloy subjected to quasi-static loading in ambient environment

A dual phase Ti-6A1-4V alloy was tested in uniaxial tension over a large quasi-static loading range (10^–5–10^–1 s^–1) in ambient environment. As strain rate increases, strength of the alloy was found to increase at the expense of ductility. In the low strain-rate region, strain rate sensitivity of the material experienced a gradual decrease during plastic deformation. In the high strain-rate region, strain-rate sensitivity of the material was largely constant for most part of the plastic deformation. The different rate dependent behaviours are believed to be caused by a change of governing plastic deformation mechanism from dislocation slip at low strain rates to twinning at the highest strain rate. Strong fractographic and metallographic evidence was obtained to understand the micromechanisms of plastic deformation.     

Combustion of a fuel drop immersed in a hot atmosphere

The combustion of a liquid fuel drop immersed in a hot atmosphere is considered when the activation energy is very large. Closed form solutions are obtained which describe a monotone variation of burning rate with Damkohler number, $\text{d}{}_1$. For some of the solutions the burning rate varies from the frozen limit at $\text{d}{}_1\text{= 0}$, to the Burke-Schumann limit at $\text{D}{}_1\text{= α}$. For all the others the burning rate varies from the frozen limit to a large $\text{D}{}_1$ limit distinct from the Burke-Schumann limit.