Experimental demonstration of heat loss and turn-down ratio for a multi-panel, actively deployed radiator

• Published in: Applied thermal engineering Vol. 178; p. 115658
• Main Authors: Mulford, Rydge B., Salt, Samuel D., Hyatt, Lance P., Meaker, Kyle S., Dwivedi, Vivek H., Jones, Matthew R., Iverson, Brian D.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.09.2020; Elsevier BV
• Subjects: Active thermal control; Actuation; Aluminum; Cooling; Copper wire; Deployable radiator; Heat conductivity; Heat exchangers; Heat loss; Heat transfer; Numerical models; Operating temperature; Panels; Resistance; Spacecraft; Spacecraft components; Spacecraft radiators; Spacecraft thermal control; Studies; Thermal conductivity; Thermal energy; Spacecraft thermal control; Deployable radiator; Active thermal control
• ISSN: 1359-4311; 1873-5606
• DOI: 10.1016/j.applthermaleng.2020.115658

•Actively controlled spacecraft radiators enable precise temperature control.•Tessellated radiators may achieve large turn-down ratios.•Fin efficiency decreases as a tessellated radiator is extended.•The Segmented Fin Algorithm (SFA) is experimentally validated. Origami-inspired, dynamic spacecraft radiators have been proposed which utilize an expandable/collapsible surface capable of large variations in emitting surface area. In this work, an experimental prototype of this concept is realized and its performance is analyzed. In particular, we demonstrate the capability of maintaining a spacecraft component at a desired operating temperature through the expansion and contraction of a collapsible radiator to control radiative heat loss. Four aluminum panels are connected via a flexible hinge constructed from interwoven copper wires and suspended from an actuating framework. The radiator panels are connected to a heated aluminum block. The radiator is placed in a vacuum environment with cooled surroundings (173 K) and the total radiative cooling power is determined as a function of radiator actuation position for a constant aluminum block temperature. As the radiator actuates from extended to collapsed, the heat transfer decreases and the fin efficiency increases. For a limited actuation range, the four-panel radiator exhibits a turn-down ratio (largest cooling power / smallest cooling power) of 1.31. A numerical model validated in this work predicts a turn-down ratio of 2.27 for actuation over the full range of radiator positions in surroundings at 4 K. Future revisions that exhibit an increase in panel and hinge thermal conductivities and utilizing eight panels would yield a turn-down ratio of 6.01. Assuming infinite thermal conductivity and infinite hinge conductance, the turn-down ratios for two, four and eight panel radiators, respectively, are 2.00, 3.98, and 7.92.