Thermophotovoltaic energy in space applications: Review and future potential

Preparation, modification, and coating for carbon-bonded carbon fiber composites: A review

In this study, WO3 films were prepared on flexible indium tin oxide/polyethylene terephthalate substrates through DC magnetron sputtering at approximately 40 °C, and the process parameters were optimized. The effects of the sputtering pressure on the microstructure, morphology, and electrochromic properties of the films were investigated using Raman spectroscopy, scanning electron microscopy, x-ray diffraction, atomic force microscopy, and electrochemical techniques. The results showed that the thickness, surface roughness, and grain size of the WO3 films changed with increasing pressure, and the optimal values of these parameters for excellent electrochromic properties of the WO3 films were 731, 53.5, and 1.79 nm, respectively, at 2.0 Pa. The optical modulation amplitude reached 84.66% at 455 nm, and the coloring and bleaching response times were 7.64 s and 6.76 s, respectively. The electrochemical impedance spectroscopy results showed that the films prepared at 2.0 Pa had the smallest Rct (41.63 Ω). 

Process optimization and effect of sputtering pressure on electrochromic properties of flexible WO3 films prepared by DC magnetron sputtering

Thermophotovoltaic energy conversion in space

The thermal energy storage and thermal-to-electric conversion components of a satellite power system were analyzed computationally. A phase- change material provided the energy storage while thermophotovoltaic cells converted the thermal energy to electrical. The phase-change mechanics were modeled and the associated system temperatures determined throughout the orbit. Using an equivalent circuit model for low-bandgap thermophotovoltaic diodes, those temperatures were then used to predict the maximum power output of the thermophotovoltaic cells. The system was modeled at five different altitudes. Two different thermophotovoltaic cells, gallium antimonide (GaSb) and gallium indium arsenide antimonide (GaInAsSb), were evaluated, and the system was analyzed when there were no voids in the phase-change material and when there were voids present. For all situations evaluated, the GaInAsSb cell produced significantly more power, but experienced greater variation in performance. The presence of voids in the phase-change material significantly lowered the power available during eclipse.

Thomas R. Amundson

Papers

Numerical power output predictions for low-bandgap thermophotovoltaic cells coupled with a latent-heat energy storage system