Low Solar Absorptance, High Emittance Performance Thermochromic VO2-Based Smart Radiator Device

Abstract

Thermochromic vanadium dioxide (VO2)-based smart radiator devices (SRDs) display emittance variation with changes in temperature, making them very promising for energy-efficient thermal control of spacecrafts in general, and nanosatellites in particular. However, the high solar absorptance of the VO2-based SRDs remains too high for their intended application. Based on an approach combining optical simulation and experimental work, I demonstrate that an additional top stack layer alternating between high and low refractive indices made of a-Si(25 nm)/SiO2(67 nm) reduces the solar absorptance of a VO2-based SRD by 35% (from 0.43 to 0.28) while keeping the emittance performance of the SRD within the requirements for the intended application (low-temperature emittance εL = 0.35, high-temperature emittance εH = 0.81 and emittance tuneability with temperature Δε = 0.46). I also discuss factors to consider while designing additional top stack layers alternating between high and low refractive indices to further decrease the SRD’s solar absorptance without affecting its emittance performance.

Actively Tunable “Single Peak/Broadband” Absorbent, Highly Sensitive Terahertz Smart Device Based on VO2

“…The appropriate design of the resonant structure enables the absorber to possess multiple resonance frequencies, each leading to a strong absorption. Furthermore, under the excitation of external terahertz waves, the interaction and coupling between the excited electromagnetic modes on the TIA structure cause the resonance frequencies to be closely spaced, resulting in overlapping and coinciding absorption peaks, ultimately achieving broadband absorption [44]. Thus, it can be concluded that the combination of the circular ring and the square disk constitutes a successful resonant structure.…”

Switchable and Tunable Radiative Cooling: Mechanisms, Applications, and Perspectives

“…Typical structures of VO 2 -based STRCs with their performance: multilayer, metasurface, and core–shell. ,,,,,,,,− Filled symbols correspond to experimentally demonstrated STRCs while open ones indicate theoretical designs without experimental verifications.…”

Transparent spacecraft smart thermal control device based on VO2 and hyperbolic metamaterials

“…1 As an important technology for spacecraft thermal control devices, smart radiation devices (SRDs) with variable emission are important for reducing the load and size of spacecraft and adapting to the complex and changing thermal environment of space. [2][3][4][5][6] Currently, there are several ways to realize the variable emission, such as thermochromism [7][8][9][10] and electrochromic variable emission. [11][12][13][14] In contrast to the latter, the former allows the emission to be adjusted autonomously according to the temperature of the controlled equipment, enabling intelligent thermal control of the temperature of the controlled equipment.…”