Measurement of Total Hemispherical Emittance of Spacecraft Thermal Control Coatings at Low Temperatures

Spacecraft payloads that operate at cryogenic temperatures often use passive thermal control systems that incorporate a variety of thermal control coatings to reject heat to space. The thermal performance of these systems depends significantly on the emittance of their thermal control coatings. This...

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Bibliographic Details
Published in:Heat transfer engineering 2012-07, Vol.33 (9), p.792-799
Main Authors: Yenni, Govinda R., Ambirajan, Amrit, Sundaresan, Narasinganallur K., Ramasamy, Arumugam
Format: Article
Language:English
Subjects:
Applied sciences
Calorimetry
Coating
Cryogenic engineering
Cryogenic temperature
Emittance
Energy
Energy. Thermal use of fuels
Exact sciences and technology
ISRO
Materials and auxiliary equipments used in energy engineering
Polyurethane resins
Spacecraft
Temperature
Thermal control coatings
Thermodynamics
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Summary:Spacecraft payloads that operate at cryogenic temperatures often use passive thermal control systems that incorporate a variety of thermal control coatings to reject heat to space. The thermal performance of these systems depends significantly on the emittance of their thermal control coatings. This paper presents total hemispherical emittance measurements carried out at the ISRO Satellite Centre (ISAC) for thermal control coatings: Aeroglaze Z307 absorptive conductive polyurethane black coating (from 8 0K to 150 K) and PUC conductive black polyurethane coating (from 70 K to 200 K). The experiments were conducted in vacuum using a steady-state calorimetric method. This paper highlights the importance of obtaining a steady state for accurately estimating the emittance at cryogenic temperatures and the criterion for achieving this. The results indicate that the emittance in the cryogenic temperature range increases with temperature for the coatings considered in this paper. Determination of the uncertainty in the experimental results is also presented. Further, the sensitivity of emittance estimates to chamber wall emittance is discussed.
ISSN:0145-7632
1521-0537
DOI:10.1080/01457632.2012.646870