Modelling of transient two-phase heat transfer for spacecraft thermal management

A computational method for predicting the two-phase transient fluid flow and heat transfer characteristics within a reservoir of the capillary-pumped-loop, intended to be used for spacecraft thermal management, has been developed. The model is based on the enthalpy formulation in an axisymmetric configuration. The reservoir operates under a constant thermodynamic pressure by allowing mass exchange between the reservoir and the outside loop. Both 1 g and 0 g environments have been considered to assess the effects of gravity on the reservoir performance. Depending on the gravity level, the power input and the reservoir orientation, three different convection modes have been identified, namely, the thermocapillary mode, the buoyancy mode, and the rapid-expansion mode (caused by interface movement). The impact of these modes on the performance of the reservoir and the associated physical phenomena have been discussed.