Thermal-hydraulic analysis of the two-phase annular flow under microgravity

The design of the two-phase flow loops applied for thermal control systems of future spacecraft requires knowledge of two-phase flow and heat transfer phenomena under microgravity conditions. This paper deals with a fundamental approach for evaporators or cold plates in two-phase flow loops. A straight evaporator tube was mathematically modeled as a simplified thermal configuration of the cold plate. Simultaneous ordinary differential equations for the two-phase annular flow under microgravity conditions were derived from the separated flow model, and numerical analyses were conducted for the purpose of parametric studies. As a result, properties' distribution of the working fluid along the flow direction, critical limits of the working conditions, and the thermal performance difference owing to the working fluids were clarified. © 1999 Scripta Technica, Heat Trans Asian Res, 29(1): 45–58, 2000