A Two-Phase Flow and Heat Transfer Model for Zero Gravity.

Abstract

Abstract : The power of future spacecraft are expected to grow considerably in the near future, and this will require more efficient thermal transport techniques. Due to high heat transfer coefficient, two-phase gas-liquid loops are expected to be used for removal and transport of heat to space radiators. The design of such cooling systems requires a knowledge of two-phase flow and heat transfer at reduced and zero gravities. The objective of this study was to develop or extend the earth gravity models for the two-phase friction multiplier, the void quantity relation, and the forced convective heat transfer coefficient to zero gravity situations. Turbulent mixing length theory was used to develop a model for the two-phase fluid and heat transfer parameters. The velocity, density, and temperature distributions were derived by solving the conservation equations for a continuous medium and assuming equal turbulent exchanges of momentum, density, and heat. The flow was assumed to be locally homogeneous, and the void distribution was allowed to vary within the channel. The results show that the model predicts all the correct physical trends. The model contains a free parameter which should be specified from experiments at zero gravity, simulated zero gravity, or conditions where the effect of gravity can be neglected. Additional keywords: Equations; Weightlessness.