Comparison of vapor cooling characteristics of a triply periodic minimal surface and other channel geometries

Abstract

Vapor cooling shield is a key technology for long-term cryogenic propellant storage in space. Cooling channels with a triply periodic minimal surface embedded inside are expected to improve its cooling performance. Herein, a cooling channel with a triangle cross-section embedded gyroid structure, a type of the triply periodic minimal surface structure, was additively manufactured. The pressure drop and heat transfer performances of the channel were experimentally measured using liquid nitrogen vapor. Furthermore, in addition to the gyroid-embedded channel, three channels with different cross-sections were fabricated for comparison: circular, triangle, and triangle with a step/groove on the bottom. The gyroid-embedded channel exhibited unique characteristics, with a thermal conductance that was approximately 40% higher than that of the channel with a simple triangle cross-section, but an excessive pressure drop of approximately 50 times higher than that of the other cross-sections. This denotes that strong vortex and turbulence and the flow separation cause excess pressure drop in the gyroidembedded channel. The pressure drop characteristic of the gyroid-embedded channel against the Reynolds number completely differed from that of the other channels, and the pressure drop of the gyroid-embedded channel can be estimated assuming analogy with particle packed beds.

Keywords

• rocket
• cryogenic propellant
• convective heat transfer
• pressure drop
• additive manufacturing
• gyroid