Argon gas flow through an internal interrupted finned tube was investigated to obtain heat transfer and frictional pressure drop data. The results were plotted against the same data for corresponding louvered plate-finned surfaces

Namkoong, D., Jr.

English

NASA Technical Reports Server

December 1967	 Brief 67-10555 
NASA TECH BRIEF
	
1 
NASA Tech Briefs are issued to summarize specific innovations derived from the U.S. space program, 
to encourage their commercial application. Copies are available to the public at 15 cents each 
from the Clearinghouse for Federal Scientific and Technical Information, Springfield, Virginia 22151. 
Study Made of Heat Transfer and Pressure Drop Through
Tubes with Internal Interrupted Fins 
To increase the transfer of heat, extended surfaces 
are used in many applications. Among the most com-
mon types of extended surfaces are fins on the outside 
surfaces of tubes (such as on evaporators and con- 
densers), and continuous and louvered fins in compact 
flat-plate heat exchangers. More recently, it has been 
shown that internal finning can be used to advantage. 
For example, recent designs in space-power-conver-
sion systems indicate that the size of gas heat ex-
changers can be reduced within performance limits by 
the proper choice of internal finning. Further, it has 
been shown that, for particularly stringent pressure 
drop and size requirements, the internal extended 
surfaces must be staggered to frequently reform the 
boundary layer of the flowing fluid. However, very 
little data pertinent to internal, interrupted, finned 
tubes has been available, particularly at very low 
Reynolds numbers, i.e., under 2500. To obtain perti-
nent data, a test program was undertaken. 
Argon gas flow through an internal interrupted 
finned tube was investigated to obtain heat transfer 
and frictional pressure drop data, with and without 
heat addition, fora range of Reynolds numbers from 
350 to 2200. The results were plotted against the same 
data for corresponding louvered plate-finned surfaces. 
The heat transfer values obtained had the same 
trend as those for louvered plate-finned surfaces over 
a rangeof Reynolds numbers from 800 to 1900, and the
obtained data curve was displaced approximately 15 
percent below the reference curve. For lower Reynolds 
numbers, there was a wider discrepancy. 
The friction factor values obtained were no different 
between cold flow and heat addition. Comparison of 
the obtained data curve with the reference curve for 
louvered plate-finned surfaces revealed similar shapes 
and identical average slopes, with the obtained data 
curve displayed approximately 10 percent below the 
reference curve. 
Note:	 - 
This investigation has been reported in NASA 
Technical Memorandum TM-X-1428, Experimental 
Results of Heat Transfer and Pressure Drop of Argon 
Flowing Through Single Tube with Internal Inter-
rupted Fins, which may be obtained from: 
Technology Utilization Officer 
Lewis Research Center 
21000 Brookpark Road 
Cleveland, Ohio 44135 
Reference: B67-10555 
Patent status: 
Inquiries about obtaining rights for the commer-
cial use of this invention may be made to NASA, 
Code GP, Washington, D.C. 20546. 
Source: David Namkoong, Jr. 
(LEW- 10280) 
Category 05 
This document was prepared under the sponsorship of the National 
Aeronautics and Space Administration. Neither the United States 
Government nor any person acting on behalf of the United States
Government assumes any liability resulting from the use of the 
information contained in this document, or warrants that such use 
will be free from privately owned rights.
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Study made of heat transfer and pressure drop through tubes with internal interrupted fins

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