Heat Transfer Enhancement of Twisted Tape Inserts in Turbulent Pipe Flows

• Published in: Nihon Kikai Gakkai rombunshuu. B hen Vol. 61; no. 588; pp. 3044 - 3051
• Main Authors: Fujita, Yasunobu, M., Alexander Lopez
• Format: Journal Article
• Language: Japanese; English
• Published: The Japan Society of Mechanical Engineers 1995
• Subjects: Swirl Flow
• ISSN: 0387-5016; 1884-8346
• DOI: 10.1299/kikaib.61.3044

Experimental data of liquid and vapor flows of R 113 for Re=5000∼400000 were obtained for both a plain tube and snugly fitted twisted tape insert tubes. No evidence of tape fin effects was found in the heat transfer characteristics of a stainless steel tape insert when compared to a Teflon tape insert. For twist ratios γ = 5.9, 10.0 and 16.0, improvements in heat transfer of up to 35% were observed. Based on a simple consideration of the heat transfer enhancement mechanisms of twisted tape inserts, a Dittus and Boelter-type correlation for a plain tube was modified to include twisted tape effects. For such a case, use of available plain-tube data was recommended to maximize the accuracy of the proposed correlation. The trade-off between pressure loss and heat transfer enhancement was considered before determining the overall desirability of twisted tape inserts.