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Abstract

The inverse heat conduction method (IHCM) and three-dimensional (3D) computational fluid dynamic (CFD) in combination with are used to select the appropriate flow model and near-wall treatment for the mixed convection of the annular finned tube heat exchanger. Thus, the numerical results obtained by all k-ε models and near-wall treatments are yielded for 4 m/s ≤ Va ≤ 5 m/s. First, IHCM combined with is applied to estimate and Q values. The obtained estimates of and Q are used as reference values for CFD. The results show that the Tk and results obtained by the standard (STD) k-ε model with the standard wall function (SWF) are closer to and the estimates of than those by the realizable (REAL) and RNG k-ε models with various wall functions for Va of 4-5 m/s. The value obtained from the STD k-ε model with SWF, Va =5 m/s and S=15 mm may be 1.14 times that of the RNG k-ε model and 0.48 times that of the REAL k-ε model. The value of the RNG k-ε model with SWF is about 1.6-1.7 times that with EWT for S = 5 mm and Va = 4 m/s and 5 m/s. These differences mean that the appropriate flow model needs to be varied with Va to obtain more accurate numerical results. The y+ of RNG and STD k-ε models does not exceed 3. However, the y+ of the REAL k-ε model exceeds 6. To our best knowledge, no studies have explored this issue and the present investigation tries to bridge this gap.

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