Thermal Performance Prediction in the Air Gap of a Rotor-Stator Configuration: Effects of Numerical Models

This study is dedicated to a numerical investigation of convective heat transfer on the rotor surfaces of a rotor-stator configuration that is typically found in large hydro-generators. The computational fluid dynamics calculations with two turbulence modelling approaches are used to predict the flow structure and heat transfer in the air gap of the rotor-stator configuration. The steady state mixing plane approach is employed at the interface to couple the rotor and stator components. Results s...     

咖啡中丙烯酰胺检测方法及含量研究进展

由于丙烯酰胺对人体有神经毒性和潜在的致癌性,在美国,咖啡烘焙、咖啡粉末和速溶咖啡中丙烯酰胺都有限量。目前测定咖啡中丙烯酰胺的方法较多,每种方法各有利弊。主要介绍测定咖啡中丙烯酰胺的4种方法:气相色谱法,高效液相色谱法,气相色谱串联质谱法和液相色谱串联质谱法。总结在各种类咖啡中丙烯酰胺含量检测方法的最新进展。     

A NOVEL QUICK-CLOSING PROBE FOR MEASURING LOCAL PARTICULATE PHASE DENSITY IN GAS-PARTICLE SUSPENSIONS

ABSTRACT

An innovative quick-closing probe system was designed, built, and tested for measuring the local particulate phase density of gas-particle suspensions. Experiments with glass beads and powder coals were conducted in a horizontal channel with an aspect ratio of 11 to 1, and also in a 0·25 m I.D. bench-scale vortex chamber. Results of particle density distributions in these two systems indicated the ability of the probe to perform in highly turbulent, swirling, dilute and intermediate phase gas-particle suspension flows. The probe was connected with a microcomputer-assisted particle weighing system for data collection and reduction. Comparison of measured data by this probe with calculated results was assessed. Since this probe requires no calibration curve nor empirical equation, it serves as a primary standard for particle density measurements. The design features, working principle, component characteristics, overall performance, and test results are discussed in this paper.     

Study of MEH–PPV/PCBM active layer morphology and its application for hybrid solar cell performance

Surface morphologies of MEH?CPPV:PCBM active layers were optimized by investigating ITO substrate treated with oxygen and nitrogen plasma. This treatment effectively improved smoothness, transmittance, and contact angle of ITO??s, resulting in good anode contacts for hybrid device structures. The consistently improved performance of hybrid solar cells was also achieved. The surface properties of treated and untreated ITO substrates were compared by contact angle, four point probe, scanning electron microscopy, and atomic force microscopy.     

水电站过渡过程计算中的反击式水轮机边界条件及迭代收敛条件

探讨了水电站过渡过程数值计算中水轮机边界条件基本方程及其迭代算法稳定性问题，从理论上推导出两种迭代算法的收敛判别条件。得到反映水流动能(或惯性)与势能比值的收敛判别变量T，当水流势能占优势时，即T≤1，第一迭代算法收敛；当水流惯性占优势时，即T>1，第二迭代算法收敛。这两个条件互补，从而证明反击式水轮机边界条件是全范围内可求解的。该判别条件已经在实际工程计算中得到验证和运用。     

Development of an On-line Flow Rheometer for Mineral Slurries

Abstract

This paper reports on the development of an on-line flow rheometer for characterising the rheological behaviour of settling mineral slurries. The instrument is a modified concentric cylinder viscometer in which the slurry is continuously circulated to keep the particles in suspension. The rheometer is designed based on the fundamentals of helical flow, which is the combination of tangential Couette and axial annular flows, and thus satisfies both the basic requirements of viscometric principles and the restrictions caused by the heterogeneous nature of the material. A strong emphasis is placed on developing a correct and accurate method for extracting fundamental rheological properties from the experimental data, without relying on any empirical calibrations or corrections. The data reduction procedure developed is firmly based on the theory of helical flow and has been extensively tested and validated with model fluids of different rheological behaviour. Testing of the flow rheometer and the data reduction method is still progressing with real slurries, but the results obtained so far have strongly indicated the practical usefulness of the instrument for continuous on-line measurements of the flow properties of settling slurries.     

A Study of the Denaturation of Egg White Proteins during Freezing Using Differential Scanning Calorimetry

Differential Scanning Calorimetry was used to determine the effect of freezing rate, thawing conditions, storage time, and storage temperature on the enthalpy of denaturation of frozen egg white. Viscosity, foam specific gravity and foam instability of the product were also determined. Loss of enthalpy of denaturation was increased by slower freezing rates, higher thawing temperatures, higher storage temperatures, and longer storage times. Conalbumin suffered greater losses, and ovalbumin smaller losses, than egg white itself. Changes in egg white viscosity, foam specific gravity and foam instability varied depending on the processing variable tested and had no clear-cut relation with losses in enthalpy of denaturation.     

木鳖果热泵低温干燥工艺研究

木鳖果是越南的一种常见高营养水果,近年来越南木鳖果产业发展迅速,但对其干燥研究较少,本文采用热泵低温干燥的方法,对木鳖果进行了干燥研究,确定木鳖果干燥的最佳工艺参数,并分析比较干燥对营养成分的影响。结果表明：风速不变,风温越高干燥物料所需时间越短,感官评定就越差,胡萝卜素损失越大;风温不变,风速越高干燥物料所需时间越短,感官评定越差,胡萝卜素损失越大;木鳖果热泵干燥最佳工艺参数为：风温：50 ℃;风速：10 m/s。