ABSTRACfThe heat transfer enhancement mechanisms and the performance of parallel-plate-fin heat exchangers are studied numerically by solving the unsteady two-dimensional Navier Stokes and energy equations. Different fm arrangements are considered and the effect of boundary layer restart and self-sustained oscillatory mechanisms on heat transfer enhancement and overall performance have been compared. Results of grid dependence study showed satisfactory convergence of the solution. These computations were performed efficiently on the massively parallel connection machine (CM5).

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This paper describes the development of a straightforward, entropy-based method for evaluating air-side heat exchanger performance. Using energy conservation, the appropriate rate equations, and the second law of thermodynamics, all energy interactions were cast into their available-work equivalents with heat transfer rate limitations. The proposed method improved on previous techniques in two ways. First, it placed value explicitly on heat duty, recognizing system design constraints and external entropy generation. Second, it accounted for marginal entropy generation due to coupling between the system and the heat exchanger. The effects of the heat exchanger design on the system can cause significant exergy destruction and must be considered by any good performance measure. The proposed methods were applied to the evaluation of a condenser in a vapor-compression system. The condenser example is discussed here in detail, to explore design tradeoffs.