Two-phase flow distribution and heat transfer characteristics in parallel channels: A flow resistance network model and structural design strategies

Boiling two-phase flow is an effective solution for heat dissipation in high-heat-flux devices, but severe flow maldistribution can readily occur in parallel channels, leading to local heat-transfer deterioration. Meanwhile, conventional three-dimensional numerical simulations often struggle to balance prediction accuracy and computational efficiency in the optimization of complex two-phase flow channels. To address these challenges, this study developed an efficient flow resistance network model that incorporates phase change and abrupt variations in local resistance. For a Z-type system under a high heat load, an iterative branch-diameter design strategy and a constrained parametric header-dimension design strategy are proposed. The comprehensive comparison shows that the header-dimension design strategy significantly outperforms the branch-diameter design strategy. When the inlet and outlet header diameters are set to 4 mm and 20 mm, respectively, the non-uniformity of the flow-rate ratio and the non-uniformity of outlet vapor quality decrease by 96.6% and 95.9%, respectively, compared with the initial configuration. The selected asymmetric-header configuration not only decreases the maximum outlet vapor quality but also reduces the total system pressure drop by 6.8%. This strategy combines high uniformity, low energy consumption, and fabrication simplicity, providing practical guidance for the design of compact two-phase heat exchange systems.