Thermal Control Schemes for a Micro-Satellite with All-Active and Selectively Active Solar String Designs

Abstract

In this study, a finite element model of a micro-satellite named X-SAT was developed to perform heat transfer analysis and design a passive thermal control scheme in the form of thermal coatings, film, and paints. To start with, the modeling philosophy and computational methodology were introduced along with the suitable assumptions made. A typical thermal control scheme was proposed and implemented using SINDA/G-NEVADA software. The sensitivity of the results to the software settings was then assessed. It was observed that the limits on the ray counts for Monte Carlo simulation in RENO and VEGAS routines play a vital role in deciding reliability of the results, especially the temperature gradients within solar panels. Subsequently, two types of solar panel designs, one with all-active solar strings and other with selectively active solar strings, were examined. When the panels with all-active type of solar cell strings were adopted, heat dissipation through shunt regulators posed a challenge for thermal control. Various scenarios for the second case with high-efficiency, selectively operable solar strings were also simulated. For both case studies, a sun-tracking mode and an overhead pass-imaging operation were considered for the worst hot and cold cases. The results showed that the switchable string design was preferable in terms of operational flexibility and thermal control.