The air-side thermal-hydraulic performance of flat-tube and round-tube heat exchangers is compared by applying a second-law-based performance measure developed by DeJong and Co-workers (1997). Correlations from the literature are used to characterize Colburn j- and f-factors. The operating conditions with optimal thermodynamic performance are calculated for individual heat exchangers and compared. The results show similar thermodynamic performance for flat-tube and round-tube heat exchangers at optimal conditions. However, the current database reflects more favorable performance for flat-tube heat exchangers at higher heat transfer rate per unit surface area- reflecting the advantage of lowered material requirement for a flat-tube heat exchanger. The strength of the current method is that performance comparisons are made between groups of heat exchangers using the optimal condition for each sample.
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