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Proceedings of the 27th National and 5th International ISHMT-ASTFE Heat and Mass Transfer Conference December 14-17, 2023, IIT Patna, Patna-801106, Bihar, India
December, 14-17, 2023, Bihar, India

Experimental studies on local heat transfer characteristics in annular channel flows with wire coils as turbulence promoters

Get access (open in a dialog) DOI: 10.1615/IHMTC-2023.990
pages 613-618


Experimental studies on the local heat transfer characteristics in an annular region with wire coils wound over the external surface of the inner tube are reported. Circular cross section wire coils were used with diameter (e) to hydraulic diameter (Dh) ratios (e/Dh) of 0.08 and 0.14. The experiments were performed for Reynolds number (Re) equal to 5000, 7500 and 10000 with wire pitch (P) to diameter ratio, P/e equal to 6, 12 and 18. The aim of this study is to analyze the local variation of the Nusselt number (Nu) over the inner tube. The Nu variations are discussed based on the possible flow mechanism in the annular channel. The results demonstrate that the utilization of wire coils induces turbulence by means of flow separation, which significantly impact the local Nu. The heat transfer results also shows that the swirl flow along the wire coil is considerable for high P/e due to low helix angle. To assess the performance of wire coils for heat transfer enhancement, the Performance Evaluation Criteria (PEC) was employed. The PEC values were determined to be greater than 1.25 for all wire coil configurations across all Re, thus justifying the practicality of wire coils.