Computational results were obtained for turbulent flow and heat transfer in curved tubes, representative of helically coiled heat exchangers. Following a grid refinement study, grid independent predictions from alternative turbulence models (k-omega, SST k-omega and RSM-omega) were compared with DNS results and experimental pressure drop and heat transfer data. Using the SST k-omega and RSM-omega 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-omega model with wall functions. Following the validation study, the RSM-omega model was used to compute friction coefficients and Nusselt numbers in the range Re = 1.4x10^4 8x10^4, Pr = 0.7 - 5.6 and coil curvature = 3x10^-3 - 0.3. Power-law correlations were found unsuitable to fit the Re-, Pr- and curvature- dependence of the Nusselt number, while the use of a properly formulated momentum-heat transfer analogy collapsed all results with high accuracy.
|Numero di pagine||11|
|Rivista||International Journal of Thermal Sciences|
|Stato di pubblicazione||Published - 2010|
All Science Journal Classification (ASJC) codes