Active phase change for a kernel nulling interferometry

2020 ◽  
Author(s):  
Harry-Dean Kenchington Goldsmith ◽  
Michael J. Ireland ◽  
Frantz Martinache ◽  
Nick Cvetojevic ◽  
Stephen J. Madden
Keyword(s):  
Phase Change ◽  
Active Phase ◽  
Nulling Interferometry

scholarly journals Switchable Ultrathin Quarter-wave Plate in Terahertz Using Active Phase-change Metasurface

2015 ◽  
Vol 5 (1) ◽  
Author(s):  
Dacheng Wang ◽  
Lingchao Zhang ◽  
Yinghong Gu ◽  
M. Q. Mehmood ◽  
Yandong Gong ◽  
...  
Keyword(s):  
Phase Change ◽  
Active Phase ◽  
Quarter Wave Plate ◽  
Wave Plate ◽  
Quarter Wave

Designing an active phase change material package for thermal and qualitative protection of meat

2019 ◽  
Vol 21 ◽  
pp. 100362 ◽  
Author(s):  
Neda Omidi Arjenaki ◽  
Nafiseh Soltanizadeh ◽  
Nasser Hamdami
Keyword(s):  
Phase Change ◽  
Phase Change Material ◽  
Active Phase ◽  
Change Material

Thermodynamic Design of a Phase Change Thermal Storage Module

1996 ◽  
Vol 118 (2) ◽  
pp. 89-96 ◽  
Author(s):  
M. Conti ◽  
C. Bellecci ◽  
Ch. Charach
Keyword(s):  
Phase Change ◽  
Numerical Study ◽  
Storage System ◽  
Fluid Flows ◽  
Active Phase ◽  
Thermal Storage ◽  
Design Parameters ◽  
System A ◽  
Removal Processes ◽  
Change Material

This paper analyzes the irreversibilities due to the heat transfer processes in a latent heat thermal storage system. The Thermal Storage Module (TSM) consists of a cylindrical shell that surrounds an internal coaxial tube. The shell side is filled by a Phase Change Material (PCM); a fluid flows through the inner tube and exchanges heat along the way. The most fundamental assumption underlying this study is that the exergy of the hot fluid stream in the active phase is discharged into the environment and completely destroyed, unless it is partially intercepted by the storage system. A numerical study is conducted to identify and to minimize the thermodynamic losses of the storage and removal processes. The dependence of the second-law efficiency of the system on various design parameters is investigated and discussed.

Power-Efficient Phase Change Memory Using Silicon Carbide as a Buffer Layer

2017 ◽  
Vol 898 ◽  
pp. 1812-1816 ◽  
Author(s):  
Tian Qi Guo ◽  
San Nian Song ◽  
Le Li ◽  
Lan Lan Shen ◽  
Shi Long Lv ◽  
...  
Keyword(s):  
Silicon Carbide ◽  
Phase Change ◽  
Buffer Layer ◽  
High Speed ◽  
High Efficiency ◽  
Phase Change Memory ◽  
Active Phase ◽  
Metal Electrode ◽  
Power Efficient ◽  
Change Memory

Power consumption has long been a great obstacle in phase change memory technology. Silicon carbide was introduced to be a buffer layer between the phase change material and the metal electrode in this work. The results showed that the new structure mitigated the energy consumption and maintained the advantage of high speed. This is attributed to the thin SiC buffer layer that helps confine the generated Joule heat inside the active phase change volume and form more conducting paths by the high efficiency of the heat utilization. Additionally, another key role — inhibition of the material separation, is conducive to achieving stable and sustainable electrical operations.

scholarly journals Methods to Characterize Effective Thermal Conductivity, Diffusivity and Thermal Response in Different Classes of Composite Phase Change Materials

Materials ◽  
2019 ◽  
Vol 12 (16) ◽  
pp. 2552 ◽  
Author(s):  
Elisabetta Gariboldi ◽  
Luigi P. M. Colombo ◽  
Davide Fagiani ◽  
Ziwei Li
Keyword(s):  
Thermal Conductivity ◽  
High Temperature ◽  
Phase Change ◽  
Effective Thermal Conductivity ◽  
Phase Change Materials ◽  
Thermal Response ◽  
Active Phase ◽  
Length Scale ◽  
Fe Simulations ◽  
Passive Phase

The phase change materials (PCMs) used in devices for thermal energy storage (TES) and management are often characterized by low thermal conductivity, a limit for their applicability. Composite PCMs (C-PCM), which combine active phase (proper PCM) with a passive phase with high conductivity and melting temperature have thus been proposed. The paper deals with the effect of length-scale on thermal characterization methods of C-PCM. The first part of the work includes a review of techniques proposed in the scientific literature. Up to now, special focus has been given to effective thermal conductivity and diffusivity at room or low temperature, at which both phases are solid. Conventional equipment has been used, neglecting length-scale effect in cases of coarse porous structures. An experimental set-up developed to characterize the thermal response of course porous C-PCMs also during active phase transition at high temperature is then presented. The setup, including high temperature-heat flux sensors and thermocouples to be located within samples, has been applied to evaluate the thermal response of some of the above C-PCMs. Experimental test results match Finite Elements (FE) simulations well, once a proper lattice model has been selected for the porous passive phase. FE simulations can then be used to estimate temperature difference between active and passive phase that prevents considering the C-PCM as a homogeneous material, to describe it by effective thermo-physical properties. In the engineering field, under these conditions, the design steps for TES systems design cannot be simplified by considering C-PCMs as homogeneous materials in FE codes.

scholarly journals Phase-Change Metasurface by U-Shaped Atoms for Photonic Switch with High Contrast Ratio

Coatings ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1499
Author(s):  
Xiaoyu Ma ◽  
Ruirui Song ◽  
Zhihua Fan ◽  
Shaolin Zhou
Keyword(s):  
Phase Transition ◽  
Phase Change ◽  
High Efficiency ◽  
Contrast Ratio ◽  
Active Phase ◽  
Hybrid Design ◽  
High Contrast ◽  
Metal Insulator Metal ◽  
Phase Tuning ◽  
Low Efficiency

Currently, diverse metasurfaces act as exotic platforms enabling versatile wave regulations in deep-subwavelength level for ultracompact integration. To address the existing issues of passive nature and low-efficiency in wave controls, one type of metasurface for active phase tuning is proposed in this paper by integrating the phase-change dielectric of Ge2Sb2Te5 into the of U-shaped meta-atoms. Specifically, the phase-change-based hybrid design of Ge2Sb2Te5-integrated metalens switch is demonstrated and numerically confirmed with switchable focusing. The well-defined metal-insulator-metal (MIM) setup is used to enable high-efficiency reflective wavefront tunig and practical Ge2Sb2Te5 phase transition. Upon the phase transition between the amorphous and crystalline states of Ge2Sb2Te5, the cross-polarized component of reflected waves in the given wavelength range is switched “on” (maximized) for as-designed geometric phase plus meta-lensing or “off” (minimized) for no lensing with ultra-high contrast ratio of ~36:1. As a result, such hybrid design of phase-change metasurface may provide a promising route for active photonic device with compact integration.

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