A Dynamic Two-Phase Component Model Library for High Heat Flux Applications

Pumped two-phase systems using mini or microchannel heat sink evaporators are prime candidates for high heat flux applications due to relatively low pumping power requirements and efficient heat removal in compact designs. A number of challenges exist in the implementation of these systems including: ensuring subcooled liquid to the pump to avoid cavitation, avoiding dry out conditions in heat exchangers that can lead to failures of the components under cooling, and avoiding flow instabilities that can damage components in an integrated system. To reduce risk and cost, modeling and simulation can be employed in the design and development of these complex systems, but such modeling must include the relevant behavior necessary to capture the above dynamic effects. To this end, a component model library has been developed in this work that demonstrates the ability to model dynamic and steady-state flow characteristics commonly observed in pumped two-phase refrigeration systems using microchannel heat sinks. The library is comprised of components that can either be used to model individual components or be coupled with other components to form an integrated system. The dynamic model of the microchannel cold plate component is based on common formulations of the time dependent mass, momentum, and energy balances, which are solved using the finite volume method to capture the two-phase flow behavior. Additionally, to accurately capture pressure drop and heat transfer, friction factors and heat transfer coefficients are based on correlations that compare well with a comprehensive list of academic publications. The mathematical description of the components, the implementation through Simulink and graphical user interfaces, and the application of the toolset will be presented herein. Comparison to hardware results will be shown along with verification of the tool’s ability to capture critical pumped two-phase phenomena such as dry out and flow instabilities.