Two-phase loops with several capillary evaporators are being developed for a variety of existing and future space applications. While modeling of loop heat pipes with one or two conventional evaporators is relatively straightforward and can be done, for example, using Excel VBA, modeling of loops with several three-port or four-port evaporators requires more specialized software such as Thermal Desktop™.
This paper presents steady state Thermal Desktop™ (Sinda/Fluint) models for systems with three main and one secondary capillary evaporator. The main evaporators have four ports and are interconnected with multiple fluid lines with bends, valves, and connectors. The system components also includes a temperature-controlled two-phase reservoir, condenser, back-pressure regulator, local heat exchangers, etc.
The modeling provided better understanding of the critical fluid-flow mechanisms encountered in the experimental two-phase system. While there are several ways to interconnect the four-port evaporators together, modeling also helped to select more reliable configurations capable of operating with the main evaporators located on different elevation levels and with non-uniform heat load distribution.