Heat exchanger unidirectional

Heat exchanger, unidirectional A heat ex changer that is used to provide a heat exchange in one direction only. 

Conductive heat transfer in all solid components, radiative heat exchange between all diffusive surfaces in the unidirectional solidification furnace, and the Navier-Stokes equations for the melt flow in the crucible are coupled. 

Analytical results presented in the preceding section are useful for well-defined constant cross-sectional surfaces with essentially unidirectional flows. The flows encountered in heat exchangers are generally very complex, having flow separation, reattachment, recirculation, and vortices. Such flows significantly affect Nu and/for the specific exchanger surfaces. Since no analytical or accurate numerical solutions are available, the information is derived experimentally. Kays and London [20] and Webb [47] presented many experimental results reported in the open literature. In the following, empirical correlations for only some important surfaces are summarized due to space limitations. 

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