An Excel User Interface for Modeling LHPs in SINDA/FLUINT 2004-01-2555
Loop Heat Pipe (LHP) Technology has become an accepted technology for thermal management of spacecraft. Despite the acceptance of the technology, there remains a lack of understanding about how to analyze these devices, creating the myth that inadequate tools exist for modeling LHPs and CPLs (capillary pumped loops).
LHPs are two-phase devices with a very tight thermal coupling to their environment. Consequently these systems must be modeled in a manner capable of capturing both thermal and fluid behavior. Over the past decade various programs have been written to model LHPs and CPLs, however the majority of them have been either design-specific or focused on capturing a specific behavior within the system. SINDA/FLUINT is a thermal/fluid modeling code fully capable of capturing both heat transfer and fluid dynamics of an LHP. In addition it provides the flexibility to model any portion of the system in as much or as little detail as needed. Unfortunately, the perception that FLUINT is too difficult to learn has precluded many engineers and technologists from learning how to model LHPs.
A recently developed Application Programming Interface (API) provides a means of launching and controlling SINDA/FLUINT from a separate stand-alone software program. To support the analysis needs of engineers who are interested in evaluating LHPs and performing system level studies, but who do not have the resources required become fluent with SINDA/FLUINT, a Microsoft Excel-based front end has been developed using this API. The resulting LHP Launch Control Panel is a simple Excel-based user interface requiring no knowledge of SINDA/FLUINT nor any need to purchase licenses if no changes are required to the underlying model.
This paper will provide an overview of the LHP Launch Control Panel, discuss typical analysis results, and provide some guidelines on bracketing the LHP performance for stochastic phenomena such as evaporator core state. In addition it will provide information for the advanced user on how to further customize the tool for their needs. The Excel-based LHP model is available in a licensed or unlicensed SINDA/FLUINT mode.