scholarly journals Tunable Duplex Metalens Based on Phase-Change Materials in Communication Range

Nanomaterials ◽  
2019 ◽  
Vol 9 (7) ◽  
pp. 993 ◽  
Author(s):  
Wei Bai ◽  
Ping Yang ◽  
Shuai Wang ◽  
Jie Huang ◽  
Dingbo Chen ◽  
...  
Keyword(s):  
Phase Change ◽  
Phase Change Material ◽  
Phase Change Materials ◽  
Three Dimensional ◽  
Special Unit ◽  
Compact Size ◽  
Unit Cells ◽  
First Time ◽  
Change Material ◽  
Different Sources

Metalenses recently have attracted attention because of their more compact size in comparison with conventional lenses; they can also achieve better optical performance with higher resolution. Duplexer is an interesting function of a metalens that can distinguish different sources and divide them into two parts for specific purposes. In this article, we design tunable duplex metalenses with phase-change material Ge2Sb2Te5 for the first time. Two types of special unit cells are designed to modulate the incident lights, and four metalenses are designed based on the two types of unit cells. Specific phase profiles are calculated for different sections of metalens in which the corresponding unit cells are settled; accordingly, the metalenses can focus the incident lights at any positions according to our design. Moreover, the metalenses become selectable via tuning the state of phase-change material, which means that the output light field can be actively controlled. The proposal of our tunable duplex metalenses will offer new opportunities for active three-dimensional imaging or optical coding.

Study on the Preparation and Properties of PEG Phase Change Materials Fixed by Semi-IPN

2011 ◽  
Vol 299-300 ◽  
pp. 654-658
Author(s):  
Hong Zhang ◽  
Xiao Lei Wang ◽  
Qian Qian Wang
Keyword(s):  
Phase Change ◽  
Phase Change Material ◽  
Phase Change Materials ◽  
Three Dimensional ◽  
Molar Ratio ◽  
Good Thermal Stability ◽  
Dimensional Network ◽  
Mass Fractions ◽  
Optimum Formula ◽  
Change Material

Semi-IPN phase change material (PCM) which is suitable for the temperature adjustment textile field is prepared by solution copolymerization. The structure of framework material is a three-dimensional network prepared by N-hydroxymethyl acrylamide, and the phase change material is prepared by polyethylene glycol with molecular weigh 2000. The orthogonal experimental method is used for determining the optimum formula and investigating the various factors on the phase change material properties. Structure and properties of the composite properties are synthesized by SEM, DSC, TGA. The result shows: the advanced process of making composite phase change material is that PEG owns 70% of the overall mass fractions, initiator owns 2.5% of monomer mass fractions, the molar ratio of cross-linker monomer is 1:8, the reaction time is 3 hours, and mass ratio of monomer to water is 1:6. The prepared composite material is distributed uniformly of framework holes, and it has a well fixed effect to the phase change material, which the phase transition temperature is 32.92 °C, the enthalpy is up to 108.41 J / g. It also has a good thermal stability, and applies to the spinning environment which the temperature is not higher than 300 °C.

Multiscale modeling frameworks for architecture: Designing the unseen and invisible with phase change materials

2018 ◽  
Vol 16 (2) ◽  
pp. 104-122 ◽  
Author(s):  
Billie Faircloth ◽  
Ryan Welch ◽  
Martin Tamke ◽  
Paul Nicholas ◽  
Phil Ayres ◽  
...  
Keyword(s):  
Phase Change ◽  
Phase Change Material ◽  
Phase Change Materials ◽  
Three Dimensional ◽  
Multiple Linear Regression Model ◽  
Multiscale Model ◽  
Material Behavior ◽  
Prototype Model ◽  
Time Data ◽  
Change Material

Multiscale design and analysis models promise a robust, multimethod, multidisciplinary approach, but at present have limited application during the architectural design process. To explore the use of multiscale models in architecture, we develop a calibrated modeling and simulation platform for the design and analysis of a prototypical envelope made of phase change materials. The model is mechanistic in nature, incorporates material-scale and precinct scale-attributes, and supports the design of two- and three-dimensional phase change material geometries informed by heat transfer phenomena. Phase change material behavior, in solid and liquid states, dominates the visual and numerical evaluation of the multiscale model. Model calibration is demonstrated using real-time data gathered from the prototype. Model extensibility is demonstrated when it is used by designers to predict the behavior of alternate envelope options. Given the challenges of modeling phase change material behavior in this multiscale model, an additional multiple linear regression model is applied to data collected from the physical prototype in order to demonstrate an alternate method for predicting the melting and solidification of phase change materials.

scholarly journals Actively Tunable Metalens Array Based on Patterned Phase Change Materials

2019 ◽  
Vol 9 (22) ◽  
pp. 4927 ◽  
Author(s):  
Wei Bai ◽  
Ping Yang ◽  
Shuai Wang ◽  
Jie Huang ◽  
Dingbo Chen ◽  
...  
Keyword(s):  
Phase Change ◽  
Adaptive Optics ◽  
Phase Change Materials ◽  
Phase State ◽  
Large Area ◽  
Dynamic Display ◽  
Unit Cells ◽  
The Common ◽  
First Time ◽  
Change Material

Recently, the metalens has been investigated for its application in many fields due to its advantages of being much smaller than a conventional lens and is compatible with nano-devices. Although metalenses have extraordinary optical performance, it is still not enough in some occasions such as wavefront detection for adaptive optics and display for large area applications. Using a metalens array is an ideal solution to solve these problems. Unfortunately, the common metalens array cannot be adjusted once it is fabricated, which limits its range of application. In this article, we designed an actively tunable metalens array for the first time by arranging the patterned phase change material Ge2Sb2Te5 (GST) appropriately. For the metalens array designed at the wavelength of 4.6 μm, it had excellent broadband performance in the range from 4.5 μm to 5.2 μm. On the other hand, by tuning the phase state of GST, the focus and display of the metalens array can be controlled, acting as switching on or off. Furthermore, any graphics constructed with patterned focal spots can be achieved when the metalens array has sufficient secondary unit cells. The proposed metalens may have potential application value in the adaptive optics and dynamic display field.

Numerical Thermal Performance Investigation of an Electric Motor Passive Cooling System Employing Phase Change Materials

2021 ◽  
Author(s):  
Ali Deriszadeh ◽  
Filippo de Monte ◽  
Marco Villani
Keyword(s):  
Phase Change ◽  
Phase Change Material ◽  
Electric Motor ◽  
Phase Change Materials ◽  
Cooling System ◽  
Passive Cooling ◽  
Time Step ◽  
Cooling Performance ◽  
Passive Cooling System ◽  
Change Material

Abstract This study investigates the cooling performance of a passive cooling system for electric motor cooling applications. The metal-based phase change materials are used for cooling the motor and preventing its temperature rise. As compared to oil-based phase change materials, these materials have a higher melting point and thermal conductivity. The flow field and transient heat conduction are simulated using the finite volume method. The accuracy of numerical values obtained from the simulation of the phase change materials is validated. The sensitivity of the numerical results to the number of computational elements and time step value is assessed. The main goal of adopting the phase change material based passive cooling system is to maintain the operational motor temperature in the allowed range for applications with high and repetitive peak power demands such as electric vehicles by using phase change materials in cooling channels twisted around the motor. Moreover, this study investigates the effect of the phase change material container arrangement on the cooling performance of the under study cooling system.

Three-dimensional computational study in a corrugated pipe inserted system filled with phase change material

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Ömer Akbal ◽  
Hakan F. Öztop ◽  
Nidal H. Abu-Hamdeh
Keyword(s):  
Phase Change ◽  
Phase Change Material ◽  
Computational Analysis ◽  
Computational Study ◽  
Three Dimensional ◽  
Simple Algorithm ◽  
Melting Time ◽  
Geometrical Parameters ◽  
Content Type ◽  
Change Material

Purpose The purpose of this paper is to make a three-dimensional computational analysis of melting in corrugated pipe inserted system filled with phase change material (PCM). The system was heated from the inner pipe, and temperature of the outer pipe was lower than that of inner pipe. Different geometrical ratio cases and two different temperature differences were tested for their effect on melting time. Design/methodology/approach A computational analysis through a pipe with corrugated pipe filled with PCM is analyzed. Finite volume method was applied with the SIMPLE algorithm method to solve the governing equations. Findings The results indicate that the geometrical parameters can be used to control the melting time inside the heat exchanger which, in turn, affect the energy efficiency. The fastest melting time is seen in Case 4 at the same temperature difference which is the major observation of the current work. Originality/value Originality of this work is to perform a three-dimensional analysis of melting of PCM in a corrugated pipe inserted pipe.

scholarly journals Performance Improvement of a Household Refrigerator using Phase Change Material

2021 ◽  
Vol 16 (1) ◽  
pp. 032-041
Author(s):  
Pradeep N ◽  
Somesh Subramanian S
Keyword(s):  
Energy Storage ◽  
Phase Change ◽  
Phase Change Material ◽  
Phase Change Materials ◽  
Energy Savings ◽  
Storage System ◽  
Thermal Storage ◽  
Latent Heat Storage ◽  
Peak Loads ◽  
Change Material

Thermal energy storage through phase change material has been used for wide applications in the field of air conditioning and refrigeration. The specific use of this thermal storage has been for energy storage during low demand and release of this energy during peak loads with potential to provide energy savings due to this. The principle of latent heat storage using phase change materials (PCMs) can be incorporated into a thermal storage system suitable for using deep freezers. The evaporator is covered with another box which has storage capacity or passage through phase change material. The results revealed that the performance is increased from 3.2 to 3.5 by using PCM.

Dissipative particle dynamics study of nano-encapsulated thermal energy storage phase change material

RSC Advances ◽  
2014 ◽  
Vol 4 (74) ◽  
pp. 39552-39557 ◽  
Author(s):  
Zhonghao Rao ◽  
Xinyu You ◽  
Yutao Huo ◽  
Xinjian Liu
Keyword(s):  
Energy Storage ◽  
Phase Change ◽  
Phase Change Material ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Thermophysical Properties ◽  
Phase Change Materials ◽  
Dissipative Particle Dynamics ◽  
Particle Dynamics ◽  
Change Material

The nano-encapsulated phase change materials (PCM), which have several good thermophysical properties, were proposed as potential for thermal energy storage.

Phase-Change Materials and Building Energy Saving

2013 ◽  
Vol 683 ◽  
pp. 106-109
Author(s):  
Xiao Gang Zhao ◽  
Ying Pan
Keyword(s):  
Phase Change ◽  
Energy Saving ◽  
Phase Change Material ◽  
Building Materials ◽  
Phase Change Materials ◽  
Heat Storage ◽  
Building Energy ◽  
Storage Performance ◽  
Building Energy Saving ◽  
Change Material

Phase change materials, abbreviated as PCM, due to the excellent heat storage performance, have been used as building materials and got more and more attention in recent years. The article introduce the building application of phase change material, and discuss its contribution to the building energy saving.

scholarly journals Effect of phase change material using in building thermal comfort applications through several climate conditions.

2020 ◽  
Vol 170 ◽  
pp. 01007
Author(s):  
Marwa El Yassi ◽  
Ikram El Abbassi ◽  
Alexandre Pierre ◽  
Yannick Melinge
Keyword(s):  
Thermal Comfort ◽  
Phase Change ◽  
Phase Change Material ◽  
Phase Change Materials ◽  
Chemical Change ◽  
Thermal Inertia ◽  
Temperature Fluctuations ◽  
High Energy ◽  
Climate Conditions ◽  
Change Material

Nowadays, buildings sector contributes to climate change by consuming a considerable amount of energy to afford thermal comfort for occupants. Passive cooling techniques are a promising solution to increase the thermal inertia of building envelopes, and reduce temperature fluctuations. The phase change materials, known as PCM, can be efficiently employed to this purpose, because of their high energy storage density. Among the various existing solutions, the present study is dedicated to solid-liquid phase change materials. Temperature evolution (according to their defined temperature range) induces the chemical change of the material and its state. For building applications, the chemical transition can be accomplished from liquid to solid (solidification) and from solid to liquid (melting). In fact, this paper presents a comparative thermal analysis of several test rooms with and without phase change materials embedded in a composite wallboard in different climates. The used PCM consist in a flexible sheet of 5 mm thickness (Energain, manufactured by the company DuPont de Nemours). The main properties of such a commercial solution have been delivered by the manufacturer and from analyses. The room model was validated using laboratory instrumentations and measurements of a test room in four cities: Lyon; Reading and Casablanca. Results indicate that this phase change material board can absorb heat gains and also reduce the indoor air temperature fluctuations during daytime. The aim of the study is to show the benefits of this layer with phase change material and compare it in different climatic zones.

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