Phase-change heat transfer of bare surface evaporator with phase-separating wick in downward facing orientation

Liquid-vapor, phase-change heat transfer using wicks can provide reliable and high flux cooling capability, especially in microgravity applications. However, the maximum removal capacity, also known as Critical Heat Flux (CHF), is related to capillary-driven liquid supply limit and/or vapor limit. A key develop a novel wick structure, offering efficient well pathways. In this study, Bare Surface Evaporator with Phase-Separating Wick (BEPSW) examined understand limits downward facing orientation for environment. The BEPSW consists of bare surface evaporator evaporation, distributed, sintered-particle post phase-separating enhanced removal. fabricated from copper disk 19.1 mm diameter, while are manufactured 10 3 layers sintered particles, respectively. measured function superheat different post-post pitch distances (Lp = 2.5, 3.5, 4.5, 7 mm) average particle sizes ( 350 550 μm), distilled water working fluid. results show that CHF increases distance decreases Lp 3.5 both due increased through wicks, it below 2.5 entrainment limit, i.e., observed at mm. Transfer Coefficient (HTC) μm size 184 W/cm2 (24.9°C superheat) 7.7 W/cm2-K (144 flux), respectively, 207 (44.3°C 5.4 (118 flux) size, models, capillary-viscous limits, predict optimal showing increasing given geometries. This type limitation controls CHF, either or Also, exceeds distance, large permeability.