Enhancement of Natural Convection Heat Transfer and Development of High-Performance Heat Transfer Plate Using Grid Fins

强化自然对流换热及开发高性能网格翅片传热板

基本信息

批准号：
04650185
负责人：
KITAMURA Kenzo
金额：
$ 1.28万
依托单位：
Toyohashi University of Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1992
资助国家：
日本
起止时间：
1992 至 1993
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-04650185/
关键词：
Natural Convection Heated Plate Heat Transfer Enhancement High-Performance Heat Transfer Plate Fin Visualization 加熱平板

项目摘要

This research project consists of two parts. The one part is to investigate the heat transfer and fluid flow of natural convection over a horizontal, heated plate. The another part is to develop the enhancement technique for the natural convection heat transfer from a horizontal plate. In the first part, the special concern was directed to the local heat transfer characteristics over the heated plate. The following four regions were found to appear over the plate with the distance from the plate edge. These are (1)the laminar boundary layr region at the very vicinity of the plate edge, (2)the separation region, where the above boundary layr flow separates three-dimensionally, (3)the turbulent flow region and (4)the impinging flow region, where the main stream from the both edges impinge with each other and turn to the vertical direction. The heat transfer coefficients show minimum in the turbulent flow region which covers considerable portion of the plate. Thus, the key for the heat transfer enhancement exists in this region. In the second part, a technique was developed to increase the heat transfer coefficients of the turbulent region. For this purpose, rectangular grid fins were installed on the heated plate. The grids inhibit the mainstream from the edges to the center of the plate and promote the cellular motion within the grid. The apparent heat transfer coefficients of thus treated plate reached double and triple as much as those of the smooth plate, respectively, when the grids with height 10mm and 3mm were used.

该研究项目由两部分组成。其中一部分是研究水平加热板上自然对流的传热和流体流动。另一部分是开发水平板自然对流换热强化技术。在第一部分中，特别关注加热板上的局部传热特性。发现在距板边缘一定距离的板上出现以下四个区域。这些是（1）非常靠近板边缘的层流边界层区域，（2）分离区域，其中上述边界层流在三维上分离，（3）湍流区域和（4）冲击流区域流动区域，来自两侧边缘的主流相互碰撞并转向垂直方向。传热系数在覆盖板的相当一部分的湍流区域中显示为最小值。因此，强化传热的关键在于该区域。在第二部分中，开发了一种提高湍流区域传热系数的技术。为此，在加热板上安装了矩形网格翅片。网格抑制主流从板的边缘到中心并促进网格内的细胞运动。当使用高度为10mm和3mm的格栅时，经过处理的板的表观传热系数分别达到光滑板的两倍和三倍。