Abstract
The flow and heat transfer behavior of newly designed V-corrugated tubes with various numbers of starts (N = 2, 3, 4, and 5), depth ratios (DR = 0.02–0.14), and pitch ratios (PR = 1.0–2.0) were studied in the turbulent flow region (5000 ≤ Re ≤ 20,000). The friction factor (f), friction factor ratio (f/f0), Nusselt number (Nu), Nusselt number ratio (Nu/Nu0), and thermal enhancement factor (TEF) values are reported. The computational results indicate that the conventional spirally-corrugated tube create swirl flows while V-corrugated tubes generate a counter-rotating vortex flow that impinges upon the lower zone of the tubes and enhances fluid transfer between tube core and near-wall regions. The results also show that the f, Nu, f/f0, Nu/Nu0 monotonically increase with decreasing PR, increasing DR and N, while the TEF is dependent on a tradeoff between f/f0 and Nu/Nu0. Over the studied range, the f/f0, Nu/Nu0, and TEF were in the ranges of 1.36–43.82, 1.00–5.35, and 0.80–2.11, respectively. The maximum TEF, 2.11, was achieved with a V-corrugated tube with an N of 4, DR of 0.06, and PR of 2.0 at Re = 5000.
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