An Integrated Simulation Framework for Thermal-Mechanical Performance Analysis of Two-phase Microchannel Evaporators

In this work we present an integrated simulation framework that has been developed to numerically predict the thermal and mechanical performance of parallel two-phase microchannel evaporators for thermal management of electronic components. The simulation framework is realized by integrating an in-house two-phase flow simulator with the Ansys Mechanical Finite Element Analysis (FEA) solver. The in-house two-phase flow simulator is based on established heat transfer and pressure drop correlations and is capable of calculating two-phase heat transfer for a wide variety of parallel microchannel designs, coolant fluids, inlet flow conditions and applied heat loads. The ANSYS FEA solver, on the other hand, allows efficient computation of a three-dimensional microchannel evaporator temperature distribution for complex thermal boundary conditions, such as localized hot spots on a packaged electronic component, and the stress distribution within the microchannel evaporator due to internal fluidic pressure. The framework is validated against experimental data obtained from literature and then utilized to predict the performance of a parallel microchannel evaporator in the presence of a nominal background heat flux and several localized hot spots on the electronic component. Refrigerants with low global warming potential are studied as the cooling fluid and the inlet flow conditions are varied with respect to mass flow rate and subcooling. Both uniform and non-uniform flow across the parallel channels are considered for each refrigerant to understand the impact of flow maldistribution on mitigating hot spot temperature rise. Finally, the effect of the internal pressure developed due to the two-phase flow on the mechanical integrity of the evaporator is also studied. This integrated approach thus allows understanding the effect of a range of parameters such as refrigerant type, flow maldistribution, parallel channel geometry, and localized hot spots on both the thermal and mechanical performance of the evaporator. A comprehensive performance map is also generated to aid in identifying the optimal refrigerant type and flow conditions for a given electronics cooling application.