Multilayer Tuneable Emittance Coatings with Low Solar Absorptance for Improved Smart Thermal Control in Space Applications

2009 ◽  
Author(s):  
Emile Haddad ◽  
Roman V. Kruzelecky ◽  
Brian Wong ◽  
Wes Jamroz ◽  
Mohamed Soltani ◽  
...  
Keyword(s):  
Thermal Control ◽  
Space Applications ◽  
Solar Absorptance

scholarly journals Tailoring Thin-Film/Lacquer Coatings for Space Applications

2000 ◽  
Vol 12 (1) ◽  
pp. 105-112 ◽  
Author(s):  
Wanda C Peters ◽  
George Harris ◽  
Grace Miller ◽  
John Petro
Keyword(s):  
Thin Film ◽  
Thermal Control ◽  
Radiative Properties ◽  
Space Applications ◽  
Solar Absorptance ◽  
Film Coatings ◽  
Thin Film Coatings ◽  
Thermal Radiative Properties ◽  
Wide Range ◽  
Specular Surfaces

Thin-film coatings have the capability of obtaining a wide range of thermal radiative properties, but the development of thin-film coatings can sometimes be difficult and costly when trying to achieve highly specular surfaces. Given any space mission’s thermal control requirements, there is often a need for a variation of solar absorptance (αs), emittance (∊) and/or highly specular surfaces. The utilization of thin-film coatings is one process of choice for meeting challenging thermal control requirements because of its ability to provide a wide variety of αs/∊ ratios. The radiative properties of thin-film coatings can be tailored to meet specific thermal control requirements through the use of different metals and the variation of dielectric layer thickness. Surface coatings can be spectrally selective to enhance radiative coupling and decoupling. The application of lacquer to a surface can also provide suitable specularity for thin-film application without the cost and difficulty associated with polishing.

White Anodic Coatings on Aluminum Alloy with Low Ratio of Solar Absorptance to Infrared Emittance

2007 ◽  
Vol 336-338 ◽  
pp. 643-646
Author(s):  
Wei Qin ◽  
Bo Cui ◽  
Xiao Hong Wu ◽  
Zhao Hua Jiang
Keyword(s):  
Optical Properties ◽  
Aluminum Alloy ◽  
Low Cost ◽  
Thermal Control ◽  
Space Environment ◽  
Space Applications ◽  
Solar Absorptance ◽  
Thermal Control System ◽  
Thermal Control Coatings

White anodic coatings are gained by growth in situ on the aluminum alloy. The coatings possess stable optical properties, excellent adhesive power, low cost, stability in the space environment, and so on, which can be widely used in the thermal control system of spacecrafts. In this article, the developed Al2O3 thermal control coatings that had a low solar absorptance and a high infrared emittance were gained in the electrolyte of sulfuric acid. The influences of various process parameters, such as electrolyte temperature, current density, anodizing time, on the optical properties of the coatings were investigated. AFM and XRD were used to characterize the microstructure of the coatings. Experimental results show the anodic coatings could reach a solar absorptance value lower than 0.20 and an infrared emittance higher than 0.80. Therefore, the coatings can be applied as important thermal control coatings for space applications.

Solar Effects on Tensile and Optical Properties of Hubble Space Telescope Silver-Teflon Insulation

2006 ◽  
Vol 929 ◽  
Author(s):  
Kim K. de Groh ◽  
Joyce A. Dever ◽  
Aaron Snyder ◽  
Sharon Kaminski ◽  
Catherine E. McCarthy ◽  
...  
Keyword(s):  
Radiation Effects ◽  
Hubble Space Telescope ◽  
Strong Dependence ◽  
Thermal Control ◽  
Space Environment ◽  
Solar Array ◽  
Solar Absorptance ◽  
Space Telescope ◽  
Solar Arrays ◽  
Solar Exposure

ABSTRACTDuring the fourth servicing mission of the Hubble Space Telescope (HST), the second set of solar arrays (SA-II) was replaced with a third set and the SA-II was brought back to Earth. A section of the retrieved SA-II solar array drive arm (SADA) multilayer insulation (MLI), which experienced 8.25 years of space exposure, was provided to NASA Glenn Research Center for environmental durability analyses of the top layer of silver-Teflon fluorinated ethylene propylene (Ag-FEP). Because the SADA MLI had solar and anti-solar facing surfaces and was exposed to the space environment for a long duration, it provided a unique opportunity to study solar effects on environmental degradation of Ag-FEP, a commonly used spacecraft thermal control material. Therefore, the objective of this research was to characterize the degradation of retrieved HST SADA Ag-FEP with particular emphasis on solar radiation effects. Data obtained included tensile properties, solar absorptance, surface morphology and chemistry. The solar facing surface of the SADA was found to be extremely embrittled and contained numerous through-thickness cracks. Tensile testing indicated that the solar facing surface lost 60% of its mechanical strength and 90% of its elasticity while the anti-solar facing surface had ductility similar to pristine FEP. The solar absorptance of both the solar facing surface (0.155 ± 0.032) and the anti-solar facing surface (0.208 ± 0.012) were found to be greater than pristine Ag-FEP (0.074). Solar facing and anti-solar facing surfaces were microscopically textured, and locations of isolated contamination were present on the anti-solar surface resulting in increased localized texturing. Yet, the overall texture was significantly more pronounced on the solar facing surface indicating a synergistic effect of combined solar exposure and increased heating with atomic oxygen erosion. The results indicate a very strong dependence of degradation, particularly embrittlement, upon solar exposure with orbital thermal cycling having a significant effect.

Experimental Study of Flexible Electrohydrodynamic Conduction Pumping for Electronics Cooling

2018 ◽  
Author(s):  
Nicolas Vayas Tobar ◽  
Pavolas N. Christidis ◽  
Nathaniel J. O'Connor ◽  
Michal Talmor ◽  
Jamal Seyed-Yagoobi
Keyword(s):  
Flexible Electronics ◽  
Electronics Cooling ◽  
Thermal Control ◽  
Stable Operation ◽  
Space Applications ◽  
Manufacturing Method ◽  
Micro Scale ◽  
Wide Range ◽  
And Performance ◽  
And Control

As modern day electronics develop, electronic devices become smaller, more powerful, and are expected to operate in more diverse configurations. However, the thermal control systems that help these devices maintain stable operation must advance as well to meet the demands. One such demand is the advent of flexible electronics for wearable technology, medical applications, and biology-inspired mechanisms. This paper presents the design and performance characteristics of a proof of concept for a flexible Electrohydrodynamic (EHD) pump, based on EHD conduction pumping technology in macro- and meso-scales. Unlike mechanical pumps, EHD conduction pumps have no moving parts, can be easily adjusted to the micro-scale, and have been shown to generate and control the flow of refrigerants for electronics cooling applications. However, these pumping devices have only been previously tested in rigid configurations unsuitable for use with flexible electronics. In this work, for the first time, the net flow generated by flexible EHD conduction pumps is measured on a flat-plane and in various bending configurations. In this behavioral characteristics study, the results show that the flexible EHD conduction pumps are capable of generating significant flow velocities in all size scales considered in this study, with and without bending. This study also proves the viability of screen printing as a manufacturing method for these pumps. EHD conduction pumping technology shows potential for use in a wide range of terrestrial and space applications, including thermal control of rigid as well as flexible electronics, flow generation and control in micro-scale heat exchangers and other thermal devices, as well as cooling of high power electrical systems, soft robotic actuators, and medical devices.

Performance of Elastomeric Silicones in Ablative and Space Environments

1966 ◽  
Vol 39 (4) ◽  
pp. 1247-1257 ◽  
Author(s):  
Clyde L. Whipple ◽  
John A. Thorne
Keyword(s):  
High Vacuum ◽  
Thermal Control ◽  
Heat Fluxes ◽  
Space Environment ◽  
Space Applications ◽  
Wide Range ◽  
Environmental Extremes ◽  
Temperature Ranges ◽  
Space Environments ◽  
Thermal Control Coatings

Abstract Elastomeric silicones are among the best materials available for many ablative and space applications. In ablative applications, these materials protect launching equipment, safeguard various parts of vehicles and spacecraft during flight, and shield re-entering spacecraft. Generally, elastomeric silicones are used where ablative conditions involve low to moderate heat fluxes and shear forces. Ablative characteristics of materials can vary widely depending on polymer type, fillers, and applications techniques, and no one elastomeric silicone will perform in a wide range of ablative missions. A good knowledge of the ablative characteristics of silicone materials is required to select the best candidates for a given application. In the space environment, silicones are often used for seals, thermal control coatings, potting materials, and other applications because they perform well over wide temperature ranges, and because they are inherently stable to high-vacuum and ultraviolet conditions. Data given in this paper illustrate that silicones show little weight loss or loss of properties on exposure to space environmental extremes. Furthermore, these losses can be made almost negligible by proper conditioning of the finished elastomer.

Fundamental Study of Vapor Chamber Thermal Control Devices for Space Applications

2018 ◽  
Vol 2018 (0) ◽  
pp. 0207
Author(s):  
Soumei Baba ◽  
Kenichiro Sawada ◽  
Kohsuke Tanaka ◽  
Atsushi Okamoto
Keyword(s):  
Thermal Control ◽  
Vapor Chamber ◽  
Fundamental Study ◽  
Space Applications ◽  
Control Devices

Effects of a Void Beneath a Kapton Heater Patch in a Vacuum

2004 ◽  
Author(s):  
Ryan A. Schmidt
Keyword(s):  
Heat Flux ◽  
Hot Spot ◽  
Thermal Control ◽  
Heat Fluxes ◽  
Void Size ◽  
Conduction Path ◽  
Space Applications ◽  
Affected Area ◽  
Conduction Pathway ◽  
Substrate Temperatures

The vacuum of space can lead to some interesting heater problems. In many space applications, heater patches consisting of Inconel elements joined together with Teflon sandwiched together between two Kapton layers are bonded to a structure (substrate) to provide thermal control. A void between the heater patch and the substrate can lead to a hot spot due to the loss of conduction path from the heater to the substrate. When the heater is in a vacuum with a void beneath it, heat is transferred to the substrate by radiation and fin effects through the heater and then to the substrate. The localized hot spot can cause heater layers to separate and further reduce the conduction pathway from the affected area and eventually burnout the heater. A large enough void combined with high heater heat fluxes and substrate temperatures can induce heater failures. For this paper the sensitivity of peak temperature with respect to heat flux (power density), substrate temperature, void size, and void location is considered.

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