Thermal and Hydrodynamic Characteristics of Single-Phase Flow and Flow Boiling in a Staggered Micro-Pin-Fin Array

This study concerns thermal and hydrodynamic characteristics of water single-phase flow and flow boiling in a micro-pin-fin array. An array of 1950 staggered square micro-pin-fins with a 200×200 μm² cross-section by a 670 μm height were fabricated into a copper heat sink test section. Two inlet temperatures of 30 °C and 60 °C, and six maximum mass velocities for each inlet temperature, ranging from 183 to 420 kg/m²s, were tested. The corresponding inlet Reynolds number ranged from 45.9 to 179.6. General characteristics of single-phase flow and flow boiling were described. Predictive tools were proposed for single-phase heat transfer coefficient and pressure drop. Unique features of flow boiling heat transfer in the micro-pin-fin array were identified. The classic Lockhart-Martinelli correlation incorporating a single-phase micro-pin-fin friction factor correlation and the laminar liquid–laminar vapor combination assumption was used to predict two-phase pressure drop in the micro-pin-fin array. The predictions agreed well with the experimental data.