Tabbed transfer fins for air-cooled heat exchanger

Abstract

Heat transfer fins (110), and heat exchangers (100) incorporating such fins (110), enhancing heat transfer with acceptable pressure drop increase. The fins (110) include tabs or secondary fins bent upward and downward from the fin body at a selected bend angle. All or a majority of the tabs are aligned with a simple flow path or with local flow paths for cooling air adjacent the fins (110) to minimize turbulence and pressure drop. The tabs are planar and generally aligned parallel to the simple flow path or local flow paths and are arranged so as to serve as a plurality of sites for starting new boundary layers by offsetting the tabs such that downstream tabs are not shadowed by upstream tabs. The tabs have a height sufficiently large to extend the tabs out into boundary layers on the fin (110). The tabs provide more uniform flow over fins (110) and shrink wake size behind tubes (120).

Description

CROSS REFERENCE TO RELATED APPLICATIONS [0001] This application claims the benefit of U.S. Provisional Application No. 60 / 486,071, filed Jul. 10, 2003, which is incorporated by reference herein in its entirety.CONTRACTURAL ORIGIN OF THE INVENTION [0002] The United States Government has rights in this invention under Contract No. DE-AC36-99GO-10337 between the United States Department of Energy and the National Renewable Energy Laboratory, a Division of the Midwest Research institute.BACKGROUND OF THE INVENTION [0003] 1. Field of the Invention [0004] The present invention relates generally to heat exchangers that utilize fins or plates on or in contact with tubes, pipes, or plates to transfer heat away from the working fluid in the tubes, pipes, or plates, and more particularly, to heat transfer fins, and heat exchangers or condensers that include such fins, that include a plurality of tabs extending from the fins to provide enhanced heat transfer on the air side of the heat exchange...

AI Technical Summary

Benefits of technology

The present invention provides an improved design for heat transfer fins in heat exchangers that enhances heat transfer while minimizing pressure drop. The fins have numerous tabs that are bent upward and downward from the body of the fin. The tabs are positioned in a way that they do not shadow each other, and they are angled in relation to the flow of cooling gas. The tabs are also positioned to allow the material of the fin to be retained while still enhancing heat transfer. The fins have openings that disrupt the boundary layer on the fin surface and reduce turbulence and pressure drop. The method for fabricating the fins involves punching holes in the fin and bending the material at a bend angle. The fins have porosity of less than 50 percent to optimize heat transfer. Overall, the invention improves the design of heat transfer fins in heat exchangers.

Problems solved by technology

Third, the openings in the main fin surface disrupt the boundary layer on that surface thus enhancing heat transfer.

Images