6533b871fe1ef96bd12d26e7

RESEARCH PRODUCT

Numerical prediction of turbulent flow and heat transfer in helically coiled pipes

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Abstract Computational results were obtained for turbulent flow and heat transfer in curved pipes, representative of helically coiled heat exchangers. Following a grid refinement study, grid independent predictions from alternative turbulence models ( k – ɛ , SST k – ω and RSM– ω ) were compared with DNS results and experimental pressure drop and heat transfer data. Using the SST k – ω and RSM– ω models, pressure drop results were in excellent agreement with literature data and the Ito correlation. For heat transfer, the literature is not comparably complete or accurate, but a satisfactory agreement was obtained in the range of available data. Unsatisfactory results, both for pressure drop and heat transfer, were given by the k – ɛ model with wall functions. Following the validation study, the RSM– ω model was used to compute friction coefficients and Nusselt numbers in the range Re = 1.4·10 4 –8·10 4 , Pr = 0.7–5.6 and δ (coil curvature) = 3·10 −3 –0.3. Power-law correlations were found unsuitable to fit the Re-, Pr- and δ -dependence of the Nusselt number, while the use of a properly formulated momentum-heat transfer analogy collapsed all results with high accuracy.