TRANSIENT MEASUREMENT OF HEAT TRANSFER COEFFICIENTS INSIDE A TUBE

宣益民; W.Roetzel

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TRANSIENT MEASUREMENT OF HEAT TRANSFER COEFFICIENTS INSIDE A TUBE

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- TRANSIENT MEASUREMENT OF HEAT TRANSFER COEFFICIENTS INSIDE A TUBE
- CIESC Journal Issue 6, (1994)
- 作者机构：
  
  南京理工大学热能工程系!南京210094,汉堡国防大学,德国
- 作者简介：
- 基金信息：
- DOI：
  CLC： Q021
- Online First：25 December 1994，
  
  Published：25 December 1994
- 稿件说明：
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宣益民, W.Roetzel. TRANSIENT MEASUREMENT OF HEAT TRANSFER COEFFICIENTS INSIDE A TUBE[J]. CIESC Journal, 1994, (6).
DOI：

宣益民, W.Roetzel. TRANSIENT MEASUREMENT OF HEAT TRANSFER COEFFICIENTS INSIDE A TUBE[J]. CIESC Journal, 1994, (6). DOI：

摘要

1前言直接测定对流换热系数的方法分稳态法和瞬态法

前者对实验条件要求苛刻.近年来

瞬态法倍受人们关注”-”.Hausen和Kast’‘·”相继阐述了利用周期变化的流体温度在固体壁内的传播特性确定对流换热系数的原理

即根据流体与固体温度变化之间的相位角滞后（或振幅衰减）确定对流换热系数.Roetzel‘”提出了一套适用于任意形式周期振荡流体温度的瞬态测量方法. 对实测的流体温度波Tf（t）

利用傅里叶级数分析方法把Tf＊）展开为傅里叶级数

其一次谐波正弦和余弦函数项的系数表述为 u。——一Ill（t）Slnwtdt.u。——一11’（）cosnddt（l）则一次谐波可表达为 01。“fslflO此十贝）（2）式（2）中

振幅u;一 Vu: + ug

相位角9一 arc ig（uc/us）

一次谐波的周期 P—Zt。

角速度。一。八。2 测量基础2.1 模型A——霉壁面导热热阻忽略管壁导热热阻

管壁的能量方程为厂dL川t一。S叮f一几）一兄凡（几一瓦）（3）若求得的管壁周期振荡温度的一次谐波为Tw（t）一u。sinnd

则流体温度超前相位角9和振幅U;分别为 .y.

o\ It【._o\“工_P_\“ 9”sfCtg WN .Ut=U。。l---- W l e -- （4）一旦实际测得相位角差贝或振幅比ff八。

即可确定对流换热系数。;.显然

当ac《a时

管外对流换热的影响甚小.当液体在管

Abstract

A transient method of measuring heat transfer coefficients inside a tube has been presented. The heat transfer coefficients between fluid and wall surface is determined by means of the propagation characteristics of periodically oscillating temperature changes. To reach this purpose

the phase shift or the amplitude ratio between fluid and wall temperatures is experimentally measured. The test apparatus has been designed and set up to carry out experiments. The discussions about the measuring method and experimental results are given in detail.

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