scholarly journals T-history analysis of aspect ratio effect on subcooling and solidification behaviour of phase change material in vertical glass tubes

2020 ◽  
pp. 326-326
Author(s):  
Rudra Murthy ◽  
Veershetty Gumtapure
Keyword(s):  
Aspect Ratio ◽  
Phase Change ◽  
Cooling Rate ◽  
Phase Change Material ◽  
Glass Tube ◽  
Mean Value ◽  
Scanning Calorimetry ◽  
Constant Length ◽  
Aspect Ratios ◽  
Change Material

The study deals with the effect of the tube aspect ratio on subcooling and the solidification behavior of phase change material (PCM) using the T-history method (THM) and is compared with the differential scanning calorimetry (DSC) analysis. Three tubes of different aspect ratios (l/d) and a constant length of 178 mm are chosen for this study. Infrared (I.R.) contour depicts that the inner surface of the glass tube and PCM initiate heterogeneous nucleation. The DSC heat flow graph indicates a higher degree of subcooling (DOS) than THM. The study of aspect ratio with and without insulation shows that the mean value of DOS is less in the insulated tube than non-insulated tube due to reduced cooling rate. The effect of the high aspect ratio is to increase the DOS due to increased cooling rate and, however, decrease the sensible heat discharge time to reach the plateau (tplt).

Effects of aspect ratio and mushy-zone parameter on melting performance of a thermal energy storage unit filled with phase change material

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Azim Memon ◽  
Anoop K. Gupta
Keyword(s):  
Energy Storage ◽  
Aspect Ratio ◽  
Mushy Zone ◽  
Phase Change ◽  
Phase Change Material ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Aspect Ratios ◽  
Zone Parameter ◽  
Change Material

Abstract An intermittent supply of energy from renewable or unconventional resources has resulted in the use of phase change materials (PCM) in thermal energy storage (TES) systems. In this work, melting and heat transfer characteristics in a rectangular enclosure of different aspect ratios (width to height) filled with a phase change material (PCM) have been studied numerically. The n-octadecane has been selected as the PCM (melting temp = 301.35 K, Prandtl number ∼ 60). We considered five different aspect ratios (AR) of the enclosure to delineate the effects of 9-fold variation in the aspect ratio. The simulations were carried out using ANSYS Fluent 19.2. In particular, extensive results have been presented and discussed in terms of the temperature contours, rate of melting and energy storage, and total time required to reach the fully melt condition. Additionally, the effect of the mushy zone parameter (A mush ) on the melting performance has also been investigated. Low values of the A mush were seen to predict the higher rate of melting. At a fixed value of A mush , ∼ 3 times faster melting rate was observed as the value of AR was reduced from 3 to 1/3. Finally, it can be concluded that melting and energy storage rate largely depends on the aspect ratio of the enclosure and the optimal choice of the value of the A mush .

Investigation of enclosure aspect ratio effects on melting heat transfer characteristics of metal foam/phase change material composites

2019 ◽  
Vol 29 (9) ◽  
pp. 2994-3011
Author(s):  
Amin Samimi Behbahan ◽  
Aminreza Noghrehabadi ◽  
C.P. Wong ◽  
Ioan Pop ◽  
Morteza Behbahani-Nejad
Keyword(s):  
Heat Transfer ◽  
Aspect Ratio ◽  
Phase Change ◽  
Phase Change Material ◽  
Metal Foam ◽  
Melting Time ◽  
Content Type ◽  
Aspect Ratios ◽  
Optimal Melting ◽  
Change Material

Purpose The purpose of this paper is to study thermal performance of metal foam/phase change materials composite under the influence of the enclosure aspect ratios (ratio of enclosure height: length). In this study, a compound metal foam/phase change material (PCM), which has been proved to be one of the most promising approaches for thermal conductivity promotion on PCMs, was used. Design/methodology/approach The PCM is considered initially at its melting temperature. The enclosure for all the cases has a constant volume with various aspect ratios. The left side of the enclosure is suddenly exposed to a thermal source having a constant heat flux, while the other three surfaces are kept thermally insulated. A two-dimensional numerical model considering the non-equilibrium thermal factor, non-Darcy effect and local natural convection was proposed. The coupling between velocity and pressure is solved using the SIMPLEC, and the Rhie and Chow interpolation is used to avoid the checker-board solutions for the pressure. Findings The effects of foam porosity and aspect ratio of the enclosure on the PCM’s melting time were investigated. The results indicated that enclosure aspect ratio plays a fundamental role in phase change of copper foam/PCM composites. For higher porosities, enclosures with bigger aspect ratios proved to led to optimal melting time. Besides, the best enclosure aspect ratio and foam porosity for a fixed-volume enclosure to have the shortest melting time are 2.1 and 91.66 per cent, respectively. However, for a specific amount of PCM inside a variable volume enclosure, the optimal melting time was for foam with ε = 95 per cent. The achieved results prove the great importance of selection of aspect ratio to benefit both conduction and convection heat transfer simultaneously. Originality/value The area of energy storage systems is original.

scholarly journals On the Melting Process of the Phase Change Material in Horizontal Rectangular Enclosures

Energies ◽  
2019 ◽  
Vol 12 (16) ◽  
pp. 3100 ◽  
Author(s):  
Duan ◽  
Xiong ◽  
Yang
Keyword(s):  
Energy Storage ◽  
Aspect Ratio ◽  
Phase Change ◽  
Phase Change Material ◽  
Liquid Fraction ◽  
Melting Process ◽  
Energy Storage Devices ◽  
Rectangular Enclosure ◽  
Aspect Ratios ◽  
Change Material

Phase change material (PCM) is one of the most important ways to store and manage energy. The melting process of PCM in a rectangular enclosure with the different aspect ratio is frequently related to some thermal energy storage devices. In this work, the melting of PCM in the horizontal rectangular enclosures heated from the different sides and the influence of aspect ratio of the rectangle are carefully studied. The enthalpy porosity technique and the finite volume method (FVM) are used to simulate the melting process numerically. The results show that the melting process of PCM can be dominated by conduction or natural convection due to the different heated sides. The melting of PCM in the enclosure heated from the bottom side is firstly affected by conduction and then mostly influenced by convection. In addition, the aspect ratio of the rectangular enclosure is found to play an important role in the melting process. Finally, a series of fitting correlations of the liquid fraction, Nusselt number and the energy storage are presented with the influence of aspect ratios in order to provide the reference for designing the rectangular container of PCM. This study is helpful for the selection of an appropriate aspect ratio and heating method to achieve the desired energy storage performance of encapsulated PCM.

Synthesis and Thermal Properties of Magnesium Sulfate Heptahydrate/Urea Resin as Thermal Energy Storage Micro-Encapsulated Phase Change Material

2017 ◽  
Vol 140 (1) ◽  
Author(s):  
Chenzhen Liu ◽  
Ling Ma ◽  
Zhonghao Rao ◽  
Yimin Li
Keyword(s):  
Particle Size ◽  
Thermal Properties ◽  
Phase Change ◽  
Magnesium Sulfate ◽  
Phase Change Material ◽  
Core Material ◽  
Scanning Calorimetry ◽  
Sulfate Heptahydrate ◽  
Encapsulated Phase Change Material ◽  
Change Material

In this study, micro-encapsulated phase change material (microPCM) was successfully synthesized by emulsion polymerization method, using magnesium sulfate heptahydrate (MSH) as core material and urea resin (UR) as shell material. The surface morphologies and particle size distributions of the microPCM were tested by scanning electron microscopy (SEM) and laser particle size analyzer. The chemical structure of microPCM was analyzed by Fourier-transform infrared spectroscopy (FTIR). The thermal properties were investigated by differential scanning calorimetry (DSC) and thermal conductivity coefficient instrument, respectively.

Developing a thermo-regulative system for nonwoven textiles using microencapsulated organic coconut oil

2020 ◽  
pp. 152808372092149
Author(s):  
Saraç E Gözde ◽  
Öner Erhan ◽  
Kahraman M Vezir
Keyword(s):  
Phase Change ◽  
Phase Change Material ◽  
Coconut Oil ◽  
Nonwoven Fabric ◽  
Scanning Calorimetry ◽  
Microencapsulated Phase Change Material ◽  
Nonwoven Textiles ◽  
Composite Fabrics ◽  
Change Material ◽  
Scanning Electron

Organic coconut oil was investigated as a bio-based phase change material in core, and melamine formaldehyde was used as shell material to fabricate microencapsulated phase change material for thermo-regulation in nonwoven textiles. The microcapsules were synthesized using in situ polymerization method. The produced microcapsules (microencapsulated phase change material) were applied by knife coating in different ratios (1:5 and 1.5:5; MPCM: coating paste by wt.) to 100% polypropylene nonwoven, porous, and hydrophilic layer of a laminated, spunbond, and double-layer fabric. The coated layer was confined within two layers of the fabric to develop a thermo-regulative system on the nonwoven fabric to regulate the body temperature in surgeries. The two layers were composed by applying heat (140°C) and pressure (12 kg/cm2). Organic coconut oil, the fabricated microcapsule, and the composite fabrics were characterized by Fourier transform infrared spectroscopy, differential scanning calorimetry, and scanning electron microscopy. Scanning electron microscopy results revealed that spherical and uniform microcapsules were obtained with an approximate particle size of 2–6 µm. Differential scanning calorimetry results indicated that microencapsulated phase change material and the composite fabrics possessed significant melting enthalpies of 72.9 and 8.4–11.4 J/g, respectively, at peak melting temperatures between 21.6 and 22.8°C within human comfort temperature range. The utilization of coconut oil as a phase change material and the composite integration of this phase change material to a nonwoven fabric bring forward a novelty for future applications.

The Properties of OMMT-PAN-Binary of Fatty Acids Blends as Phase Change Materials

2011 ◽  
Vol 239-242 ◽  
pp. 1101-1104
Author(s):  
Jing Guo ◽  
Heng Xue Xiang ◽  
Cheng Nv Hu
Keyword(s):  
Fatty Acid ◽  
Phase Change ◽  
Phase Change Material ◽  
Phase Change Materials ◽  
Heat Insulation ◽  
Cooling Curve ◽  
Polyacrylonitrile Fiber ◽  
Scanning Calorimetry ◽  
Thermal Circulation ◽  
Change Material

Using stearic acid-lauric acid binary of fatty acid as phase change material, waste polyacrylonitrile fiber (PAN) as supporting material, organic montmorillonite (OMMT) as modifier, and N, N-dimethylformamide as solvent, OMMT-PAN-binary fatty acid composite phase change materials(PCM) is prepared by solution blending. Using Scanning Electron Microscopy (SEM), Differential Scanning Calorimetry (DSC), Thermogravimetric analysis (TG) study the structure and properties of PCM, the optimized preparation techniques of PCM obtained by orthogonal tests. SEM results showed that the PCM was homogeneous structure, binary of fatty acid dispersed in the continuous phase PAN; TGA results indicated that the degradation of the phase change material can be divided into three steps; DSC results showed that the crystallization enthalpy of PCM reached 143.27 J/g, the phase change temperature was around 23°C, and the DSC thermal circulation showed good thermal stability of the PCM; cooling curve showed that the PCM had good heat insulation properties, holding time reached 800s, and after repeated thermal circulation, heat insulation properties remained the same.

Microencapsulation of n-hexadecane as phase change material by suspension polymerization

e-Polymers ◽  
2007 ◽  
Vol 7 (1) ◽  
Author(s):  
Ai Yafei ◽  
Jin Yong ◽  
Sun Jing ◽  
Wei Deqing
Keyword(s):  
Melting Point ◽  
Phase Change ◽  
Phase Change Material ◽  
Latent Heat ◽  
Suspension Polymerization ◽  
Average Diameter ◽  
Heat Of Fusion ◽  
Synthetic Surfactant ◽  
Scanning Calorimetry ◽  
Change Material

AbstractIn this study, suspension polymerization is described to fabricate microcapsules containing n-hexadecane as phase change material. In the suspension polymerization, casein is employed as emulsifier and stabilizer instead of synthetic surfactant. Microcapsules with polystyrene as shell and n-hexadecane as core have an average diameter of 3~15μm and the size distribution are narrow. Thermal properties are investigated by differential scanning calorimetry (DSC) showing that the microcapsules can store and release an amount of latent heat over a temperature range nearing the melting point of pure n-hexadecane. The latent heat of fusion of microencapsulated n-hexadecane decreases after microencapsulation. The melting point of microencapsulated n-hexadecane is near but higher than that of pure n-hexadecane, and the polymerization time has little effect on the melting point.

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