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Analysis of Thermophoretic Effect by Means of Phase Doppler Method

相位多普勒法分析热泳效应

基本信息

批准号：
07405035
负责人：
HIRANO Toshisuke
金额：
$ 15.04万
依托单位：
The University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (A)
财政年份：
1995
资助国家：
日本
起止时间：
1995 至 1997
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-07405035/
关键词：
Thermophoresis Fine Particle Temperature Gradient Particle Diameter Measurement Laser Doppler Method I-MAX Method I-MAX法

项目摘要

In this study, establishment of measuring method and analysis of measured data concerning thermophoretic effect have been conducted to accumulate the qualitaive data and establish the adequate theory.(1) Establishment of measuring method of thermophoretic velocityThe measuring method of thermophoretic velocity, which is one of the characteristic values of thermophoresis, has been established. It was realized by setting up the measuring field, in which temperature distribution is linear and quasi steady, and gas flow velocity is negligible compared with thermophoretic velocity. The measuring field was a closed space in two flat plates (90x90mm), which were placed horizontally and parallel to each other in a narrow distance (1mm) with the upper plate heated to form a temperature gradient in between. The velocity of generated convective flow, which disturbs accurate measurements, was found to be proportional to the 3rd power of the plate distance and inverse of the width of plate. By this results, the accurate measurement in the temperature gradient of about 100 K/mm could be realized when the distance was set to be narrow (1mm).(2) Accumulation of qualitative data concerning thermophoretic effectBy means of the method denoted in (1), thermophoretic velocities have been measured to accumulate the qualitative data of thermophoretic effect. Thermophoretic velocities of SiO2 particles of 1-3mm in diameter and PMMA particles of 5-30mm in diameter have been measured under the temperature gradient of up to 90 K/mm, and well reproducible data were obtained. The measured data were found to be larger than the value proposed in previous studies. This result pointed out the uncertainty of the previous studies, in which data were measured in only small temperature gradient condition. Dependence of thermophoretic velocity on temperature gradient and particle diameter was also found to be different from that in the previous studies.

在本研究中，我们对有关热湿效应的测量方法的建立和测量数据进行了分析，积累了定性的数据，并建立了充分的理论基础。(1)热湿速度测量方法的建立建立了热湿效应的特征值之一--热湿速度的测量方法。它是通过设置测场来实现的，测场内的温度分布是线性的、准稳定的，与热泳速度相比，气流速度可以忽略不计。测量范围为两个平板(90×90 mm)的封闭空间，两个平板水平平行放置一小段距离(1 Mm)，上平板受热形成温度梯度。实验发现，产生的对流速度与平板距离的3次方成正比，与平板的宽度成反比，从而影响了准确的测量。根据这一结果，在较窄的距离(1 Mm)下，可以实现100K/mm左右的温度梯度的精确测量。(2)有关热湿效应的定性数据的积累。在高达90K/mm的温度梯度下，测量了直径为1-3 mm的SiO_2颗粒和直径为5-30 mm的PMMA颗粒的热释速度，获得了重复性较好的数据。测量的数据被发现比以前研究中提出的值更大。这一结果指出了以往研究中仅在小温度梯度条件下测量数据的不确定性。热泳速度对温度梯度和颗粒直径的依赖关系也不同于以往的研究。