Tutorial on single- and two-component two-phase flow and heat transfer: Commonality and difference

Abstract

It is assessed to what extent the results of two-phase two-component flow and heat transfer research can be usefully applied to support research on the flow and heat transfer in two-phase single-component systems. The latter singlecomponent two-phase systems, envisaged for spacecraft thermal control applications, are Mechanically Pumped and Vapour Pressure Driven Loops, Capillary Pumped Loops, and Loop Heat Pipes. In these single-component systems the working fluid is a mixture of a liquid (for example ammonia, carbon dioxide, ethanol, or other refrigerants, etc.) and its saturated vapour. The two-component systems considered consist of liquid-gas mixtures, e.g. water-air. Various aspects are discussed qualitatively and quantitatively to determine commonality and difference between two physically looking similar and close, but essentially different systems. It is focused on the different pressure gradient constituents and total pressure gradients, on flow regime mapping (including evaporating and condensing flow trajectories in the flow pattern maps), on adiabatic flow and the impact of flashing, and on thermal-gravitational scaling issues. It is elucidated that, though there is a certain degree of commonality, the differences are appreciable. The conclusion is that one shall be very careful in interpreting two-component outcomes to develop single-component two-phase thermal control systems.

Development of a Mechanically Pumped Two-Phase CO2 Cooling Loop for the AMS-2 Tracker Experiment

“…-In the case of very lengthy mechanically pumped twophase loop lines the pressure (saturated temperature) gradient has to be kept small to guarantee a small endto-end pressure (saturated temperature) difference to meet the requested isothermality, and to keep the evaporator exit vapour quality below 0.15, as in flowing refrigerants the vapour quality usually increases with pressure decay [9]. Ethane is an exception, showing vapour quality increase below say 0.7, decrease above this value.…”

Thermal Modeling Issues Concerning the Mechanically Pumped Two-Phase CO2 Cooling for the AMS-2 Tracker

“…It is based on NLR's experience with two-phase heat transfer using several working fluids in various types of applications, e.g. [4,5].…”

Tutorial on Quantification of Differences between Single- and Two-Component Two-Phase Flow and Heat Transfer

“…The discussions start, like in earlier tutorials (Delil, 2001a(Delil, , 2000 with the background of the research, followed by a short general description of two-phase flow and heat transfer phenomena. The impact of the gravity level will be assessed.…”