Opportunities & Challenges for Two-Phase Flow Microchannel Heat Sinks in Nuclear Systems

Abstract

The microchannel heat sink (MCHS) has garnered significant interest in recent years due to the demand for high heat flux compact energy systems accompanying the development of increasingly compact electronic systems. While the literature on this topic has focused on the use of MCHS for heat removal from electronics, opportunities have been identified for applications to nuclear systems which could benefit from these highly compact systems.

Numerous heat transfer enhancement techniques have been proposed with the aim of improving MCHS performance through modified channel geometries and optimization of flow conditions. The characterization of two-phase boiling flow patterns and correlations to predict heat transfer and pressure drop in the associated flow regimes is an active area of ongoing research due to the inconsistent agreement between experimental data and correlations. Flow instabilities in two-phase boiling pose a significant challenge to the design of these systems due to their potential to induce boiling crisis, disturb control systems, or cause mechanical damage. Such instabilities must be well-understood and accurately predicted to ensure the safe design margins for systems relying on MCHS for thermal management; this requirement is especially important in nuclear applications.

This review aims to summarize recent efforts to model and predict flow instabilities in the design of microchannel systems and identify key areas of research that need to be addressed to enable the application of MCHS technology to heat removal in nuclear systems.