engleski

A NUMERICAL STUDY OF ENHANCED HEAT TRANSFER SURFACES FOR COMPACT HEAT EXCHANGERS

An accurate numerical method for the solution of the two-dimensional, time-dipendent incompressible fluid flow and heat transfer in complex geometries is described. The main features of the method are the space discretization with the covolume discretization of the governing equations on unstructured triangular grids, and the time discretization with the fractional step method. The accuracy of the method is checked with some standard benchmark problems. The method is applied on geometries commonly used in compact heat exchangers. Two different cases are considered: a sinusoidal and an arc-shaped wavy channel. The critical Reynolds number at which the flow exhibits the transition to unsteady state is evaluated for both cases. A good agreement between the present results, and the previously published experimental findings is obtained, indicating that our method can be successfully applied in the study, and subsequent optimization of heat transfer systems operating in time-dipendent and transitional regimes.

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