Dynamic thermal management materials attract fast-increasing interest due to their adaptability to changing environments and greater energy savings as compared to static materials. However, the high transition temperature and the low emittance tunability of the vanadium dioxide (VO 2 )-based infrared radiation regulators limit their practical applications. This study addresses these issues by proposing a smart infrared radiation regulator based on a Fabry−Peŕot cavity structure (VO 2 /HfO 2 /Al), which is prepared by high-power impulse magnetron sputtering (HiPIMS) and has the potential for large-scale production. Remarkably, the outstanding emittance tunability reaches 0.51, and the phase transition temperature is lowered to near a room temperature of 27.5 °C by tungsten (W) doping. In addition, a numerical thermal management power of 196.3 W/m 2 (at 8−14 μm band) can be obtained from 0 to 60 °C. As a proof-of-concept, the demonstrated capabilities of the VO 2 infrared radiation regulator show great potentials in a wide range of applications for the thermal management of buildings and vehicles.

Mimicry, a biological phenomenon whereby organisms can change their morphological characteristics to resemble another object, has stimulated the unprecedented development of devices that allow the manipulation of thermal emission. Herein, inspired by biological mimicry and the pattern evolution of Chinese Kirigami, this study demonstrates a universal and effective method to prepare devices that exhibit a reconfigurable and multilevel evolution of infrared (IR) thermal images based on vanadium dioxide (VO 2 ). The significant discrepancy between the phase transition temperatures of VO 2 with different tungsten doping fractions affords the reconfigurable response in thermal images to varying environmental temperatures. Particularly, the large degree of freedom afforded by evolution steps and local IR emissivity further consummates the thermal mimicry ability for diverse demands. Furthermore, the ultrafast response time, notable observation angle independence, and the active control system are also demonstrated. This study offers a new perspective for reconfigurable thermal mimetic devices and provides a new path for distinct applications such as IR communication, information encryption, and virtual/augmented reality.

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Closed supercritical carbon dioxide (S-CO 2 ) Brayton cycle is a promising alternative to steam Rankine cycle due to higher cycle efficiency at equivalent turbine inlet conditions, which has been explored to apply to nuclear, solar power, waste heat recovery, and coal-fired power plant. This study establishes 300MW S-CO 2 power system based on modified recompression Brayton cycle integrated with coal-fired circulating fluidized bed (CFB) boiler. The influences of two stages split flow on system performance have been investigated in detail. In addition, thermodynamic analysis of critical operating parameters has been carried out, including terminal temperature difference, turbine inlet pressure/temperature, reheat stages, and parameters as well as compressor inlet pressure/temperature. The results show that rational distribution of split ratio to the recompressor (SR 1 ) achieves maximal cycle efficiency where heat capacities of both sides in the low temperature recuperator (LTR) realize an excellent matching. The optimal SR 1 decreases in the approximately linear proportion to high pressure turbine (HPT) inlet pressure due to gradually narrowing specific heat differences in the LTR. Secondary split ratio to the economizer of CFB boiler (SR 2 ) can recover moderate flue gas heat caused by narrow temperature range and improve boiler efficiency. Smaller terminal temperature difference corresponds to higher efficiency and brings about larger cost and pressure drops of the recuperators, which probably decrease efficiency conversely. Single reheat improves cycle efficiency by 1.5% under the condition of 600 ∘ C/600 ∘ C/25Mpa while efficiency improvement for double reheat is less obvious compared to steam Rankine cycle largely due to much lower pressure ratio. Reheat pressure and main compressor (MC) inlet pressure have corresponding optimal values. HPT and low pressure turbine (LPT) inlet temperature both have positive influences on system performance.

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