Casimir-Polder Interaction of an Atom with a Cavity Wall Made of Phase-Change Material out of Thermal Equilibrium

We consider the out-of-thermal-equilibrium Casimir-Polder interaction between atoms of He*, Na, Cs, and Rb and a cavity wall made of sapphire coated with a vanadium dioxide film which undergoes the dielectric-to-metal phase transition with increasing wall temperature. Numerical computations of the Casimir-Polder force and its gradient as the functions of atom-wall separation and wall temperature are made when the latter exceeds the temperature of the environment. The obtained results are compared with those in experiment on measuring the gradient of the Casimir-Polder force between 87Rb atoms and a silica glass wall out of thermal equilibrium. It is shown that the use of phase-change wall material significantly increases the force magnitude and especially the force gradient, as opposed to the case of a dielectric wall.

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Thermal Characterization of a Heat Management Module Containing Microencapsulated Phase Change Material

Energies ◽

10.3390/en12112164 ◽

2019 ◽

Vol 12 (11) ◽

pp. 2164

Author(s):

H.M. Shih ◽

Yi-Pin Lin ◽

L.P. Lin ◽

Chi-Ming Lai

Keyword(s):

Phase Change ◽

Phase Change Material ◽

Wall Temperature ◽

Heat Dissipation ◽

Thermal Protection ◽

Core Material ◽

Heat Management ◽

Microencapsulated Phase Change Material ◽

Aluminum Honeycomb ◽

Change Material

In this study, a heat management module containing a microencapsulated phase change material (mPCM) was fabricated from mPCM (core material: paraffin; melting temperature: 37 °C) and aluminum honeycomb structures (8 mm core cell). The aluminum honeycomb functioned both as structural support and as a heat transfer channel. The thermal management performance of the proposed module under constant-temperature boundary conditions was investigated experimentally. The thermal protection period of the module decreased as the Stefan number increased; however, increasing the subcooling factor could effectively enhance the thermal protection performance. When the cold-wall temperature TC was fixed at 17 °C and the initial hot wall temperature was 47–67 °C, the heat dissipation of the module was complete 140 min after the hot-wall heat supply was stopped. The time required to complete the heat dissipation increased to 280 min when TC increased to 27 °C.

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Application of Ce–Eu/TiO2 phase change material as the wall material to improve the indoor environment

Journal of Materials Research ◽

10.1557/s43578-020-00037-w ◽

2021 ◽

Author(s):

Zhifang Zong ◽

Depeng Chen ◽

Chunxiao Zhao ◽

Gang Tang ◽

Yilong Ji ◽

...

Keyword(s):

Phase Change ◽

Phase Change Material ◽

Indoor Environment ◽

Wall Material ◽

Change Material ◽

Tio2 Phase

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Passive generation from a novel thermoelectric energy harvesting system model integrated with phase change material

E3S Web of Conferences ◽

10.1051/e3sconf/201911103060 ◽

2019 ◽

Vol 111 ◽

pp. 03060

Author(s):

Yoo-Suk Byon ◽

Hansol Lim ◽

Yong-Kwon Kang ◽

Soo-Yeol Yoon ◽

Jae-Weon Jeong

Keyword(s):

Phase Change ◽

Temperature Profile ◽

Phase Change Material ◽

Temperature Difference ◽

Wall Temperature ◽

Waste Heat ◽

Thermoelectric Energy ◽

Temperature Method ◽

Thermoelectric Energy Harvesting ◽

Change Material

The purpose of this research is to evaluate the performance of a novel model that incorporates a thermoelectric generator (TEG) and phase change material (PCM). The proposed model passively generates electricity using waste heat that accumulates at exterior wall surfaces. The main generator is a TEG. To maintain the temperature difference between the two sides of the TEG, PCM is located at its cold side—thus converging the heat transferred into latent heat. The proposed passive generation system is formed into a TEG-PCM block. The block can be stacked to form a wall or inserted into any part of a building that faces the sun. The experiment setup is based on a constant temperature method. The wall temperature profile is set according to solar radiation, convection, and radiative heat transfer. To replicate daily wall temperatures during the experiment, a heat plate is used to match a wall temperature profile. Step control was used for the heating plate. The resulting data shows the average temperature difference between the hot and cold sides of the TEG to be 10-20°C. The peak generated electricity was 0.08 W for a single module.

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A Parametric Investigation on Energy-Saving Effect of Solar Building Based on Double Phase Change Material Layer Wallboard

International Journal of Photoenergy ◽

10.1155/2018/1829298 ◽

2018 ◽

Vol 2018 ◽

pp. 1-8 ◽

Cited By ~ 1

Author(s):

Xiaoxiao Tong ◽

Xingyao Xiong

Keyword(s):

Phase Transition ◽

Phase Change ◽

Phase Change Material ◽

Wall Temperature ◽

Parametric Investigation ◽

Double Phase ◽

Phase Transition Temperatures ◽

Saving Effect ◽

Change Material ◽

Inside Wall

In order to further understand the thermal performance of the double phase change material (PCM) layer wallboard, the wallboard model was established and a comprehensively numerical parametric investigation was carried out. The variation laws of inner wall temperature rise and the heat flux transferred under different phase transition temperatures and thermal conductivities are presented in detail. The main results show that the temperature of the inside wall for case 2 can be reduced by about 1.5 K further compared to that for case 1. About 83% of the heat transferred from the outside is absorbed by the PCM layer in case 2. Reducing the phase transition temperature of the PCM layer can decrease the inside wall temperature to a certain extent in the period of high temperature. The utilization of double PCM layers shows much more performance compared to that of the single PCM layer case, and the temperature of the inside wall can be reduced by 2 K further.

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Heat Transfer Enhancements Using Vibration During Solidification of Paraffin

2010 14th International Heat Transfer Conference, Volume 7 ◽

10.1115/ihtc14-23146 ◽

2010 ◽

Author(s):

Johnathan Vadasz ◽

Josua Meyer ◽

Saneshan Govender

Keyword(s):

Heat Transfer ◽

Phase Change ◽

Phase Change Material ◽

Wall Temperature ◽

Vibration Frequency ◽

Initial Temperature ◽

Solidification Process ◽

Solid Material ◽

Solidification Temperature ◽

Change Material

In the current study the effects of vibration on the solidification process of phase change material (PCM) paraffin in a sphere shell are investigated. The amount of PCM used was kept constant during each experiment by using a digital scale to check the weight and a thermocouple to check the consistency of the temperature. A small amount of air was present in the sphere so that the sphere was not filled completely. Commercially available paraffin wax, RT35, was used in the experiments. Experimentations were done on a sphere of 40 mm diameter, wall temperature of 20°C below mean solidification temperature, and consistent initial temperature. A constant vibration frequency of 100 Hz was applied to the setup and results compared with that of no vibration. Samples were taken at different times during the solidification process and compared with respect to solid material present. It was found that the solidification time had been reduced significantly under the vibration. This led to the conclusion that there had been an improvement in heat transfer due to the vibration.

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Modeling of Arbitrary-Shaped Specific and Latent Heat Curves in Phase-Change Storage Simulation Routines

Journal of Solar Energy Engineering ◽

10.1115/1.2930755 ◽

1990 ◽

Vol 112 (1) ◽

pp. 29-33 ◽

Cited By ~ 13

Author(s):

G. C. J. Bart ◽

P. C. van der Laag

Keyword(s):

Computer Simulation ◽

Phase Change ◽

Latent Heat ◽

Wall Temperature ◽

Phase Change Materials ◽

Heat Storage ◽

Temperature Transition ◽

Transition Range ◽

Heat Curve ◽

Change Material

In solar heat storage, use is often made of the latent heat of phase-change materials (PCM) with a wide temperature transition range. In this paper the heat withdrawal of a slab of such a phase-change material after a step-wise change in wall temperature, and as a function of the shape of the specific and latent heat curve, has been studied with a computer simulation. It will be outlined that various shaped curves show the same heat withdrawal character as an equivalent rectangular-shaped specific heat curve. A procedure to obtain this equivalent curve will be given.

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Eexperimental Investigation of Heat Characteristics of Liquid Flow With Micro-Encapsulated Phase Change Material

Volume 10: Heat Transfer, Fluid Flows, and Thermal Systems, Parts A, B, and C ◽

10.1115/imece2008-68597 ◽

2008 ◽

Author(s):

Rami Sabbah ◽

Jamal Yagoobi ◽

Said Al Hallaj

Keyword(s):

Heat Transfer ◽

Phase Change ◽

Phase Change Material ◽

Wall Temperature ◽

Tube Wall ◽

Operating Conditions ◽

Working Fluid ◽

Tube Wall Temperature ◽

Encapsulated Phase Change Material ◽

Change Material

This experimental study investigates the effect of presence of Micro-Encapsulated Phase Change Material (MEPCM) within the working fluid on thermal performances of the cooling system. To conduct this study, an experimental setup consisting of a steel tube with an inner diameter of 4.3mm, outer diameter of 6.3mm and a length of 1,016mm is selected. 5%, 10% and 20% mass concentration MEPCM slurries with particle diameter ranging between 5–15μm were included in this study. Tube wall temperature profile, fluid inlet, outlet temperatures, the pressure drop across the tube are measured and corresponding heat transfer coefficients are determined for various operating conditions. Differential Scanning Calometery (DSC) test results for an iterative method for local variables calculation. The experimental results showed significant enhancement in heat transfer coefficient higher than 50% and reduction in tube wall temperature higher than 35%. The controlling parameters are identified and their effects on the heat transfer characteristics are evaluated and analyzed.

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Study on the Effect of Hole Size of Trombe Wall in the Presence of Phase Change Material for Different Times of a Day in Winter and Summer

Processes ◽

10.3390/pr9111886 ◽

2021 ◽

Vol 9 (11) ◽

pp. 1886

Author(s):

Yacine Khetib ◽

Abdullah Alhumaidi Alotaibi ◽

Abdullah H. Alshahri ◽

Goshtasp Cheraghan ◽

Mohsen Sharifpur ◽

...

Keyword(s):

Phase Change ◽

Wall Temperature ◽

Numerical Study ◽

Simulation Software ◽

Fluid Simulation ◽

Outlet Temperature ◽

Hole Size ◽

Trombe Wall ◽

Enhance Efficiency ◽

Change Material

In this article, a numerical study is performed on a Trobme wall in a tropical city for two seasons, summer and winter. A 1×1.5 m Trobme wall with a thickness of 15 cm is designed and analyzed. A 1-inch-diameter tube filled with PCM is used to enhance efficiency. The wall is analyzed at different times of the day for the two cold and hot seasons for different sizes of wall holes in the range of 70 to 17.5 cm when the wall height is 20 cm. A fluid simulation software is employed for the simulations. The problem variables include different hours of the day in the two cold and hot seasons, the presence or absence of PCM, as well as the size of the wall hole. The results of this simulation demonstrate that the maximum outlet temperature of the Trobme wall occurs at 2 P.M. Using PCM on the wall can allow the wall to operate for longer hours in the afternoon. However, the use of PCM reduces the outlet wall temperature in the morning. The smaller the size of the wall hole, the more air can be expelled from the wall.

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