Analytical and experimental study of single and two-phase cooling in miniature straight and helical channels.

摘要

The miniaturization of electronic circuits, higher power levels per chip and increased packaging densities have driven the trend in electronics packaging toward higher heat fluxes. High performance cooling techniques are therefore required to keep junction temperatures low for acceptable electronics reliability. High performance cooling must provide a low junction to coolant thermal resistance and the ability to absorb high heat fluxes. Additionally, for aerospace applications the cooling technology must be tolerant to adverse g-fields and be able to operate in all attitudes (gravitational orientations). This investigation was designed to evaluate and further develop the miniature spiral cold plate technology for electronics cooling with both analytical modeling and experimental testing. Despite the abundant amount of literature that has been published on both single and two-phase flow in curved passages, helices and spirals, there is only a limited amount of work reported on two-phase flow and phase change heat transfer in “small” channels. The combination of these two phenomena appears to be unique and unexplored. A series of test articles has been designed and fabricated to cover the range of feature dimensions and hydraulic parameters of a cold plate optimized by a preliminary analytical model. Testing was done over a wide range of flows and heat additions in both single-phase and two-phase conditions. Using both the single and two-phase test data, two-phase multipliers could be experimentally determined and then correlated to appropriate parameters. In some cases, test data has led to modifications of previous correlations, extending the range of application. In other cases, new correlations have been developed to predict heat transfer and pressure drop for two-phase flow in small phase flow in small helical channels.; This program has shown that the miniature spiral channel cold plate technology is viable and attractive for use by high power density electronics. With the improved understanding and ability to predict the miniature two-phase curvilinear flow, the technology can now be further matured by demonstrating the fabrication and performance testing of a prototype.