Single-phase and two-phase cooling using hybrid micro-channel/slot-jet module

This paper explores the single-phase and two-phase cooling performance of a hybrid micro-channel/slot-jet module using HFE-7100 as working fluid. Three-dimensional numerical simulation using the k-epsilon turbulent model is used to both assess the single-phase performance and seek a geometry that enhances heat removal capability and surface temperature uniformity while decreasing mean surface temperature. This geometry is then tested experimentally to validate the numerical findings and aid in the development of correlations for both the single-phase and two-phase heat transfer coefficients. The hybrid module is shown to maintain surface temperature gradients below 2 degrees C for heat fluxes up to 50 W/cm(2). Even without phase change, the hybrid module is capable of dissipating heat fluxes as high as 305.9 W/cm(2). Highly accurate single-phase correlations are developed using a superpositioning technique that consists of assigning a different heat transfer coefficient for each portion of the heat transfer area based on the dominant heat transfer mechanism for that portion. Increasing subcooling and/or flow rate is shown to delay the onset of nucleate boiling to a higher heat flux and higher surface temperature, as well as enhance critical heat flux (CHF). A correlation previously developed for hybrid micro-channel/micro-circular-jet module is deemed equally effective at predicting two-phase heat transfer data for the present hybrid module. (C) 2008 Elsevier Ltd. All rights reserved.