Advanced analysis of an ammonia loop heat pipe for space applications. Part I: the numerical model

A novel and advanced thermal model is proposed for nonstationary simulations of a loop heat pipe (LHP) with varying the heat power loads and the boundary heat flux conditions. Integrated with the time-varying conditions and thermal coupling between the LHP systems and the orbit environment, a system-level model was built in order to understand the temperature characteristics of LHP systems during the mission time. Since one critical problem for the thermal simulations of space components is linked to the long computational time, which has the effect that the numerical design and virtual prototyping for the thermal optimization is restricted to very few operating conditions, the main purpose of the research is to build an adaptive and fast model for an LHP, based on a thermal model built using the lumped parameter code SINDA/FLUINT, in order to get CPU times lower than the real times of the running device cooled by the given LHP. The procedure may be easily extended to future implementation of LHP models in other space-dedicated software, such as ESATAN.