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High Density Array of Tubes in Horizontal Tube-Bundle Evaporator

卧式管束蒸发器中的高密度管阵列

基本信息

批准号：
05555067
负责人：
FUJITA Yasunobu
金额：
$ 4.42万
依托单位：
KYUSHU UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Developmental Scientific Research (B)
财政年份：
1993
资助国家：
日本
起止时间：
1993 至 1994
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-05555067/
关键词：
Boiling in Tube Bundle Nucleate Boiling In-line Array Staggered Array Critical Heat Flux 高密度管配列

项目摘要

An experimental study on nucleate boiling heat transfer was performed to investigate various effects on heat transfer characteristics in horizontal tube bundle and to gain useful information for developing an evaporator with horizontal tubes more densely arrayd. Experiments were done for in-line and ataggered tube arrangement under the conditions of natural circulation and forced circulation of fluid within a tube bundle. Findings are as follows.(1) Compared with the performance of a single horizontal tube in pool boiling, heat transfer coefficient of tube bundle shows the same level at higher heat flux where nucleate boiling is fully established, while at lower heat flux the boiling heat transfer is highly enhanced in a bundle.(2) The above mentioned difference in performance between a single tube and a tube bundle is true for both bundles of in-line and staggered arrangement.(3) Under the condition of natural circulation a rise of heat transfer coefficient at lower heat flux is more enhanced as the location of tube is higher in a bundle.(4) In the case of forced circulation, heat transfer coefficient at lower heat flux increases with an increase of circulating flow velocity. Heat transfer coefficient increases vertically at first for lower tubes, then decreases for higher tubes.(5) As for an effect of tube pitch, a pitch to diameter ratio P/D of 1.5 shows better performance under the natural circulation, while a P/D of 1.3 is preferable for the forced circulation.

对水平管束内核态沸腾传热进行了实验研究，旨在考察各种因素对水平管束内核态沸腾传热特性的影响，为开发更密集排列的水平管束蒸发器提供有益的信息。在管束内流体自然循环和强制循环的条件下，进行了顺排和交错排管的实验。调查结果如下。(1)与单根水平管相比，在较高热流密度下，管束的换热系数基本相同，此时核态沸腾已完全形成，而在较低热流密度下，管束的沸腾换热得到了显著的强化。(2)单管和管束之间的上述性能差异对于直列和交错布置的两个管束都是真实的。(3)在自然循环条件下，低热流密度下的换热系数随管束位置的升高而增大。(4)在强制循环情况下，低热流密度下的换热系数随循环流速的增大而增大。在垂直方向上，低管的传热系数先增大，高管的传热系数先减小。(5)至于管节距的影响，1.5的节距直径比P/D在自然循环下显示出更好的性能，而1.3的P/D对于强制循环是优选的。