Recent advances in the analysis and design of trickle-bed reactors

This paper summarizes some progress in our understanding of trickle-bed reactors. The particular topics discussed in this review are the basic hydrodynamics, flow regime transition, pressure drop and holdup calculations, use of tracers, modelling of partial wetting effects, reactor design of and catalyst testing in trickle beds. The rapid advances made in these areas are critically examined and some problems which need further investigation are outlined. This paper is dedicated to Dr L K Doraiswamy on his sixtieth birthday. Dr Doraiswamy initiated a significant research programme in the area of multiphase reactors at NCL, Pune, resulting in a number of new technologies, several well-cited publications and a book in this area. One of the authors of this review (P A Ramachandran) had the privilege and pleasure of associating with this group and is grateful to the constant encouragement provided by Dr Doraiswamy. This work could not have been possible without the industrial support to the Chemical Reaction Engineering Laboratory (CREL) at Washington University and Drs P A Ramachandran and M P Duduković would like to thank all the industrial sponsors of CREL.     

Coaxial heat pipes

Heat and mass exchange is calculated for the wicks of coaxial heat pipes during convective heat transfer between a fluid and the pipe wall.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 23, No. 6, pp. 1030–1036, December, 1972.     

Recent advances in probe design for eddy current testing of heat exchangers

Basic eddy current principles and standard inspection procedures relating to heat exchanger tubing are briefly summarized. Various revolutionary probes recently introduced by Chalk River Nuclear Laboratories of Atomic Energy of Canada Limited are described. Included are: probes for inspecting ferromagnetic tubing, probes for detecting circumferential cracks and probes for detecting in regions, such as the tubesheet expansion zone, where conventional probes are not effective.     

Self-oscillations in oscillating heat pipes

Self-oscillations in oscillating heat pipes are investigated experimentally. A theoretical model of self-oscillations is constructed for the case where the heater is located at the top. Characteristic times of temperature oscillations are obtained, which agree well with experimentally obtained values (of the order of 15 s). It is demonstrated experimentally that the average operating time of a heat pipe increases abruptly with increasing number of turns. The distribution of self-oscillation times is found, which turns out to be close to Gaussian.     

Open-type miniature heat pipes

The hypothesis that systems of thermoregulation, similar to open-type micro heat pipes, exist in nature (soils, living organisms, plants) and in a number of technological processes (drying, thermodynamic cycles on solid adsorbents) is considered. The hydrodynamics and heat transfer in such thermoregulation systems differ from the hydrodynamics and heat transfer in classical heat pipes, since their geometrical dimensions are extremely small (dozens of microns), adhesion forces are powerful, the effect of the field of capillary and gravitational forces is significant, and strong interaction between counter-current flows of vapor and liquid takes place.Academic Scientific Complex A. V. Luikov Heat and Mass Transfer Institute, Academy of Sciences of Belarus, Minsk. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 65, No. 1, July, 1993.     

Investigations of the corrosion mechanism in tantalum-lithium high temperature heat pipes by ion analysis

The examination by metallography and ion-analyser of a SGS tanaalum-lithium heat pipe operated 221 hours at 1600°C confirmed the hypothesis that oxygen and yttrium as well are transported and concentrated in the heating zone. These impurities are responsible for the intergranular attack and the perforation of the wall material.     

Intensification of heat exchange in the condensation zone of centrifugal heat pipes

We give the results of the investigation of the intensification of heat exchange in the condensation zone of centrifugal heat pipes with longitudinal grooves.Translated from Inzhenerno-Fizicheskii Zhurna., Vol. 46, No. 4, pp. 538–545, April, 1984.     

Vapor flow in low-temperature heat pipes

The authors consider the influence of nonuniformity and asymmetry of the heat supply and removal in the evaporation and condensation zones of heat pipes on the characteristics of the vapor flow.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 50, No. 2, pp. 222–226, February, 1986.     

Performance limits of low-temperature heat pipes

A mathematical relation is shown (in integral as well as in criterial form) for calculating the performance limits of heat pipes. Theoretical results are compared with test data.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 25, No. 2, pp. 249–253, August, 1973.     

Problems in building vertical high-temperature heat pipes

This paper examines problems arising in building vertical high-temperature heat pipes with simple and composite wicks. The author's test results with gas-free and gas-controlled sodium heat pipes are presented.Deceased.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 38, No. 3, pp. 389–395, March, 1980.     

Determining the thermal resistance of low-temperature heat pipes

A method is proposed for calculating the thermal resistance of low-temperature heat pipes. The results are compared with test data.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 24, No. 5, pp. 881–887, May, 1973.     

瞬态热传导温度场不确定性区间数值分析

针对具有区间参数的瞬态热传导问题,建立了一种瞬态热传导温度场不确定性分析的求解模式。在空间上,采用八节点等参元技术进行离散,并且考虑了非均质和参数分布的影响。利用基于单元分析的区间有限元法和矩阵摄动理论,将不确定性系统进行分离,分别建立确定性部分和不确定性部分的有限元模型。时间域上,引入时域精细算法进行离散求解,进而得到瞬态温度场响应的区间范围。数值算例取得了满意的结果,结果表明所提求解模式的可行性和有效性。     

Recent advances in thermoelectric materials

Thermoelectric materials are crucial in renewable energy conversion technologies to solve the global energy crisis. They have been proven to be suitable for high-end technological applications such as missiles and spacecraft. The thermoelectric performance of devices depends primarily on the type of materials used and their properties such as their Seebeck coefficient, electrical conductivity, thermal conductivity, and thermal stability. Classic inorganic materials have become important due to their enhanced thermoelectric responses compared with organic materials. In this review, we focus on the physical and chemical properties of various thermoelectric materials. Newly emerging materials such as carbon nanomaterials, electronically conducting polymers, and their nanocomposites are also briefly discussed. Strategies for improving the thermoelectric performance of materials are proposed, along with an insight into semiconductor physics. Approaches such as nanostructuring, nanocomposites, and doping are found to enhance thermoelectric responses by simultaneously tuning various properties within a material. A recent trend in thermoelectric research shows that high-performance thermoelectric materials such as inorganic materials and carbon nanomaterials/electronically conducting polymer nanocomposites may be suitable for power generation and energy sustainability in the near future.     

Recent advances in fluxgate magnetometry

Fluxgate magnetometers, introduced in the 1930's, continue to be used in a variety of applications, such as magnetic air-borne detection, search and surveillance operations, nondestructive testing of materials, palaeomagnetism, and exploration of magnetic fields in space. This paper discusses recent analyses of fluxgate operation, the development of highly stable sensors for absolute measurement of weak fields, and the development of compact inexpensive low-power devices for various search and surveillance operations and for aspect sensing.     

Recent advances in Lorentz microscopy

Lorentz transmission electron microscopy (LTEM) has evolved from a qualitative magnetic domain observation technique to a quantitative technique for the determination of the magnetization state of a sample. In this review article, we describe recent developments in techniques and imaging modes, including the use of spherical aberration correction to improve the spatial resolution of LTEM into the single nanometer range, and novel in situ observation modes. We review recent advances in the modeling of the wave optical magnetic phase shift as well as in the area of phase reconstruction by means of the Transport of Intensity Equation (TIE) approach, and discuss vector field electron tomography, which has emerged as a powerful tool for the 3D reconstruction of magnetization configurations. We conclude this review with a brief overview of recent LTEM applications.