Numerical investigation of flow boiling in manifold microchannel-based heat exchangers

Abstract

Microchannel heat sinks have the potential to achieve the physical limit of phase change heat transfer. With advances in nano-/microscale fabrication techniques, important progress on microchannel heat exchangers has been made in recent years. However, the two-phase flow evolution and its influence on flow boiling at microscale remains ambiguous. Detailed information on transport process in microchannel and underlying mechanism are required for the fully understanding and further optimization of the microchannel heat sink. Here, we constructed a three-dimensional manifold microchannel-based heat exchanger model to study the two-phase flow pattern and heat transfer performance using the Phase-field method. The dynamics of vapor bubbles in microchannels of 80 μm, 150 μm, and 300 μm in depth was carefully investigated with respect to Reynolds number and thermal boundary conditions. Parameters and underlying mechanism that influence the two-phase flow evolution and heat transfer performance in the manifold microchannels are systematically analyzed. Finally, mechanism of heat transfer crisis and critical heat flux (CHF) in microchannel is studied, and strategies to optimize the flow field to delay the CHF are discussed. Our study provides detailed information on the transport process at microscale and offers opportunities for the design and fabrication of next generation microscale heat sinks.