scholarly journals Terahertz Metamaterial Modulator Based on Phase Change Material VO2

Symmetry ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 2230
Author(s):  
Yanfei Dong ◽  
Dingwang Yu ◽  
Gaosheng Li ◽  
Mingtuan Lin ◽  
Li-An Bian
Keyword(s):  
Frequency Selective Surface ◽  
Asymmetric Transmission ◽  
Dynamic Modulation ◽  
Terahertz Detection ◽  
New Type ◽  
Absorption Performance ◽  
Surface Electric Field ◽  
Bifunctional Properties ◽  
Change Material ◽  
Transmission And Reflection

In this paper, a new type of terahertz (THz) metamaterial (MM) modulator has been presented with bifunctional properties based on vanadium dioxide (VO2). The design consists of a VO2 resonator, polyimide substrate, frequency selective surface (FSS) layer, and VO2 film. Based on the metal-insulator transition (MIT) of VO2, this structure integrated with VO2 material can achieve the dynamic modulation on both transmission and reflection waves at 2.5 THz by varying the electrical conductivity value of VO2. Meanwhile, it also exhibits adjustable absorption performance across the whole band from 0.5–7 THz. At the lower conductivity (σ = 25 S/m), this structure can act as a bandpass FSS, and, at the high conductivity (σ = 2 × 105 S/m), it behaves like a wideband absorber covering 2.52–6.06 THz with absorption A > 0.9, which realizes asymmetric transmission. The surface electric field distributions are illustrated to provide some insight into the physical mechanism of dynamic modulation. From the simulated results, it can be observed that this design has the capability of controlling tunable manipulation on both transmission/reflection responses at a wide frequency band. This proposed design may pave a novel pathway towards thermal imaging, terahertz detection, active modulators, etc.

scholarly journals Hybrid Microencapsulated Phase-Change Material and Carbon Nanotube Suspensions toward Solar Energy Conversion and Storage

Energies ◽  
2020 ◽  
Vol 13 (17) ◽  
pp. 4401
Author(s):  
Jun Li ◽  
Lisi Jia ◽  
Longjian Li ◽  
Zehang Huang ◽  
Ying Chen
Keyword(s):  
Thermal Conductivity ◽  
Carbon Nanotube ◽  
Solar Energy ◽  
Energy Conversion ◽  
Solar Energy Conversion ◽  
Microencapsulated Phase Change Material ◽  
Energy Conversion And Storage ◽  
New Type ◽  
And Storage ◽  
Change Material

In this study, a new type of functional hybrid suspension for solar energy conversion and thermal energy storage was prepared by adding carbon nanotube (CNT) and microencapsulated phase-change material (MEPCM) into deionized water. MEPCM with octadecane as the core material and titania (TiO2) as the shell material was synthesized by the sol–gel method. The MEPCMs were spherical particles with diameters of 2–4 μm, and the thickness of the shell was about 100 nm. The MEPCM achieved better thermal stability and thermal conductivity than the pure octadecane due to the TiO2 shell. The melting and solidification latent heats of the MEPCM were about 154.24 and 154.26 J/g, respectively. The encapsulation efficiency of octadecane was calculated to be 65.84%. Most of all, the novel hybrid CNT and MEPCM suspensions exhibited remarkable dispersion stability owing to the stable reticular structure composed of CNT in the suspension. Compared with pure water, the thermal conductivity, specific heat of the MEPCM/CNT suspension improved by 34.48 and 43.57%, respectively and the photo-thermal conversion efficiency reached a high value of 86.0%. This work provided a new type of hybrid functional suspension towards direct absorption solar collector for solar energy conversion and storage.

Optimize the Dielectric Slab of the Tunable Active Frequency Selective Surface Absorbing Material

2012 ◽  
Vol 534 ◽  
pp. 209-214 ◽  
Author(s):  
Qian Chen ◽  
Jian Jun Jiang ◽  
Xin Xin Xu ◽  
Biao Sun ◽  
Li Zhang ◽  
...  
Keyword(s):  
Frequency Selective Surface ◽  
Dielectric Slab ◽  
Optimum Thickness ◽  
Absorption Properties ◽  
Absorbing Material ◽  
New Type ◽  
Frequency Selective ◽  
Experimental Equation ◽  
Tunable Absorption ◽  
Selection Of

Active frequency selective surface (AFSS) absorber loaded with PIN diodes is a new type of structural absorber with tunable absorption properties. This absorber is similar to a sandwich, the surface is an AFSS, the middle is a dielectric slab, and the bottom is a metallic ground. In order to design and fabricate a thin and good performance absorber, the selection of dielectric slab is very important. In this paper, we detailed investigated the effects of the dielectric slab parameters (permittivity and thickness) to the absorption properties by experiments, and an experimental equation was proposed to provide a better description about their relationship. The measured results indicated there was an optimum thickness for the dielectric slab to produce the broadest bandwidth. The experimental equation was useful to optimize the design of the absorber.

Thermal Behaviour of New Type of Plaster with PCM Admixture

2015 ◽  
Vol 710 ◽  
pp. 3-7 ◽  
Author(s):  
Jan Fořt ◽  
Milena Pavlíková ◽  
Anton Trník ◽  
Zbyšek Pavlík
Keyword(s):  
Differential Scanning Calorimetry ◽  
Indoor Environment ◽  
Storage Capacity ◽  
Heat Storage ◽  
Laser Diffraction ◽  
Scanning Calorimetry ◽  
Matrix Density ◽  
New Type ◽  
Change Material

In order to decrease the energy consumption of buildings and keep the high thermal comfort of the indoor environment, new types of plasters modified by phase change material (PCM) are developed and experimentally tested. For evaluation of the contribution of PCM admixture to plasters properties, the reference plaster is studied as well. The basic characterization of the tested plasters is done using the measurement of their bulk density, matrix density a total open porosity. For the dry plasters mixtures, the particle size distribution is accessed on laser diffraction principle. Investigation of thermal properties as main parameters affecting the thermal performance of researched materials is done by differential scanning calorimetry (DSC) and transient impulse method. The obtained results proved increased heat storage capacity of the newly developed plasters with incorporated PCM admixture.

A New Type Phase Change Energy-Saving Device for Building Field

2012 ◽  
Vol 608-609 ◽  
pp. 1147-1150
Author(s):  
Yong Qi Xie ◽  
Peng Tao Chi ◽  
Jian Zu Yu ◽  
Jun Song
Keyword(s):  
Phase Change ◽  
Maximum Temperature ◽  
Storage Device ◽  
Melting Time ◽  
Freezing Process ◽  
Maximum Temperature Difference ◽  
Copper Foam ◽  
Prototype Test ◽  
New Type ◽  
Change Material

The heat transfer enhancement in a latent heat energy storage device through embedment of copper foam (CF) is reported. The CF had a 96% porosity and the phase change material (PCM) was 25# paraffin. The CF and PCM were contained in a cuboid sample. A prototype test room was designed to numerically investigate the performance of the device. The melting and freezing process of the PCM and the day-night temperature of the room were observed. The results show that the tested totally melting time of the PCM is 8.72 hours during the daytime while the freezing time is 8.19 hours at night, and the phase change process could accomplish within 8-9 hours. The maximum temperature difference of the room is reduced 8.3°C. The room comfort could be significantly enhanced under the premise of less air conditioning energy consumption by applying the device.

scholarly journals Polarization-dependent asymmetric transmission using a bifacial metasurface

2020 ◽  
Vol 5 (11) ◽  
pp. 1487-1495
Author(s):  
Jangwoon Sung ◽  
Gun-Yeal Lee ◽  
Chulsoo Choi ◽  
Jongwoo Hong ◽  
Byoungho Lee
Keyword(s):  
Asymmetric Transmission ◽  
Arbitrary Polarization ◽  
Transmission And Reflection

Using linearly birefringent structure and induced transmission, asymmetric transmission with arbitrary polarization pair has been realized through metasurfaces, with impartment of two different phases into transmission and reflection space.

Experimental Study on Performance of Phase Change Thermal Storage Kang

2014 ◽  
Vol 525 ◽  
pp. 451-456
Author(s):  
Gang Li ◽  
Kai Pang ◽  
Lan Chi ◽  
Chang Xiang Liu ◽  
Li Jiang ◽  
...  
Keyword(s):  
Phase Change ◽  
Heating Surface ◽  
Thermal Storage ◽  
Heating Period ◽  
Upward Trend ◽  
Indoor Temperature ◽  
Average Temperature ◽  
Surface Temperature Distribution ◽  
New Type ◽  
Change Material

In this paper, the author build a new type of Kang with paraffin as its heating surface. Paraffin is a kind of phase change material ,which can stroage and release heat at a relatively constant temperature. It can make full use of the heat of the smoke in the Kang and extend the Kang heating period. We do comparison test of the the traditional Kang room and the phase change Kang room and related temperature was recorded. The tested result shows that the average temperature of the head, medium and tail of traditional Kang varies greatly,the maximum difference of the temperature is over 20°C. While the average temperatures of the head, middle and tail of the phase change thermal storage Kang are 32.59°C, 28.38°C and 26.12°C, Kang surface temperature distribution is more uniform, which improves the comfort of Kang surface. The indoor temperature with phase change thermal storage Kang shows an upward trend after the fuels burnt out until the wee hours. And the average indoor temperature is 1 °C higher than the comparision room. The phase change thermal storage Kang greatly improves the thermal comfort of its heating surface and indoor temperature.

Myristic Acid/Montmorillonite Composite as Shape Stabilized Phase Change Material for Thermal Energy Storage

2011 ◽  
Vol 332-334 ◽  
pp. 935-938
Author(s):  
Zhong Li ◽  
Shao Ming Yu ◽  
De Xin Tan ◽  
Tong He Yao
Keyword(s):  
Phase Change ◽  
Phase Change Material ◽  
Myristic Acid ◽  
Xrd Analysis ◽  
High Heat ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Analysis Technique ◽  
New Type ◽  
Change Material

A new type of shape stabilized phase change material (PCM) with good heat storage was produced by intercalating myristic acid (MA) with modifid montmorillonite (MMT). The structure, thermal properties of the composite PCM were determined by X-ray diffraction (XRD), Fourier transformation infrared (FTIR) and Differential Scanning Calorimetry (DSC) analysis technique. In the XRD analysis, expansions of the d spacings in the (001) plane were observed in all samples, indicating that the intercalation of MA in the interlayers of MMT was successfully achieved. The results of DSC indicated that the shape stabilized PCM displayed a high heat capacity (133.6 J.g-1)

Heat Energy Storage Characteristics of a New Type of PCM Heat Exchange Tube

2012 ◽  
Vol 550-553 ◽  
pp. 3131-3134
Author(s):  
Xiao Qin Zhu ◽  
Zhao Sheng Cao ◽  
Zi Yue Zhu ◽  
Jing Hua Chang ◽  
Hai Ming Gu ◽  
...  
Keyword(s):  
Energy Storage ◽  
Heat Exchange ◽  
Phase Change ◽  
Phase Change Material ◽  
Waste Heat ◽  
Heat Energy ◽  
Heat Exchange Tube ◽  
New Type ◽  
Change Material ◽  
Storage Characteristics

Heat energy storage characteristics of a new type of PCM heat exchange tube was researched, in which it took the traditional double-tube exchanger as the total construction foundation and phase change material(CaCl2•6H2O) was filled in the annular area between the inner tube and the outer tube. As air with different temperatures flowed through the PCM heat exchange tube, temperature measurements were carried out at the inlet and the outlet by the experimental system. The experimental results showed that, a new type of PCM heat exchange tube could store heat energy from the hot air by the phase change material in the annular area, and discharge the stored heat energy into the required fluid if necessary. Thus it has two functions of heat exchange and heat energy storage, and is mainly suitable for recovery and utilizations of heat energy in greenhouses, buildings, air conditioning and manifold industrial afterheat or waste heat.

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