Effect of Latent Heat to Solidification Process of Phase Change Material

2012 ◽  
Vol 174-177 ◽  
pp. 1214-1218
Author(s):  
Jin Feng Mao ◽  
Wei Hua Li ◽  
Yong Li ◽  
Bo Wang ◽  
Dong Dong Lou ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Phase Transition ◽  
Transition Temperature ◽  
Phase Change ◽  
Latent Heat ◽  
Phase Transition Temperature ◽  
Initial Temperature ◽  
Heat Storage ◽  
Theoretical Models ◽  
Storage Unit

The heat transfer characteristics of heat storage unit are analyzed by many researchers from both theoretical and experimental in solidification heat release. Most theoretical models define the initial temperature of the phase change materials is equal to the phase transition temperature, in fact, thermal storage unit in the application, its initial temperature is not equal to the phase transition temperature. Many theoretical models have not considered the impact of latent heat of solidification. In this paper, homemade inorganic hydrated salt material is used as heat storage media, packaging with a cylindrical container. The phase change heat transfer process was analyzed both from theoretical and experimental. The effect of initial temperature and the latent heat of the heat transfer material were both considered.

Study on the Microstructure and Storage Heat Performance of Mg-25Al-15Zn-xCu Alloys

2015 ◽  
Vol 1120-1121 ◽  
pp. 1104-1108
Author(s):  
Hong Yan Wen ◽  
Xiao Ming Fan ◽  
Xiao Min Cheng
Keyword(s):  
Phase Transition ◽  
Transition Temperature ◽  
Phase Change ◽  
Latent Heat ◽  
Phase Transition Temperature ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Optical Microstructure ◽  
Solid Solution Matrix ◽  
And Storage

With the help of optical microstructure(OM), X-ray diffraction(XRD) and differential scanning calorimetry(DSC), the microstructure and storage heat performance of Mg-based phase change thermal storage alloys were investigated.The results show that the microstructure of Mg-25Al-15Zn-xCu (x=0, 2%, 8% and 14%, respectivly) alloys are mainly composed of primary crystal α (Mg) solid solution matrix, β-Mg17Al12, CuZn, MgAl2Cu and Mg32(Al,Zn)49 phases. The phase transition temperature of Mg-25Al-15Zn and Mg-25Al-15Zn-8Cu alloys ​​are 412.1 °C and 405.9 °C respectively; and phase change latent heat values of that were 175.4 J/g and 209.3 J/g. The addition of Cu led to the formation of new phase, reducing the phase transition temperature and increasing the value of phase change latent heat.

Preparation of PMMA/SiO2 PCM microcapsules and its thermal regulation performance on denim fabric

2020 ◽  
Vol 49 (6) ◽  
pp. 491-499 ◽  
Author(s):  
Wei Zhang ◽  
Shang Hao ◽  
Dandan Zhao ◽  
Guiqin Bai ◽  
Xin Zuo ◽  
...  
Keyword(s):  
Phase Transition ◽  
Transition Temperature ◽  
Latent Heat ◽  
Phase Transition Temperature ◽  
Thermal Performance ◽  
Heat Storage ◽  
Thermal Regulation ◽  
Latent Heat Storage ◽  
Content Type ◽  
Denim Fabric

Purpose This study aims to evaluate the thermal performance of phase change materials (PCMs) microcapsules (MCs) attached using SiO2 microspheres and investigate the thermal regulation effect on the coated denim fabric. Design/methodology/approach The PCM microcapsule was prepared by in situ polymerization using a mixture of solid paraffin and butyl stearate as core material (CM) and methyl methacrylate as a monomer. The SiO2 microparticles were attached to the outer layer of the membrane to enhance the thermal performance of MCs. The morphology, chemical structure, latent heat storage and thermal resistance of MCs were characterized. PCM MCs were coated on the denim fabric and thermo-gravimetric analysis was conducted; thermal insulation and thermal infrared imaging performance of the coated fabrics were also investigated. Findings The diameters of SiO2 particles and PCMs MCs were 300-500 nm and 1 μm, respectively. SiO2 was wrapped on single-wall PCMs MCs with the mass ratio of 1:5. With the addition of SiO2, the phase transition temperature range of MCs increased from 34°C to 39°C, and the endothermic and exothermic latent heat decreased by 5.35 J/g and 10.07 J/g, respectively. The degradation rate of MCs was significantly slowed down at high temperature. The denim fabric coated with MCs revealed thermal regulation property. After absorbing heat, the MCs slowed down the rate of heat loss and extended the heat release time. Research limitations/implications The phase transition temperature of the composite CM was wide, and the latent heat storage was reduced. The addition of SiO2 particles can significantly slow down the rate of heat loss, but it further reduces the latent heat storage performance. Practical implications The method developed provided a simple and practical solution to improve the thermal regulation performance of fabrics. Originality/value The method of adjusting the phase transition temperature range of the composite CM is novel and many applications could be found in preparation of PCMs and thermal management.

Analysis and Design of a Paraffin/Graphite Composite PCM Integrated in a Thermal Storage Unit

2008 ◽  
Author(s):  
R. Pokhrel ◽  
J. E. Gonza´lez ◽  
T. Hight ◽  
T. Adalsteinsson
Keyword(s):  
Phase Transition ◽  
Thermal Conductivity ◽  
Transition Temperature ◽  
Phase Change ◽  
Specific Heat ◽  
Latent Heat ◽  
Phase Transition Temperature ◽  
Thermal Storage ◽  
High Energy ◽  
Melting And Solidification

The addition of latent heat storage systems in solar thermal applications has several benefits including volume reduction of storage tanks and maintaining the temperature range of the thermal storage. A Phase change material (PCM) provides high energy storage density at a constant temperature corresponding to its phase transition temperature. In this paper, a high temperature PCM (melting temperature 80°C) made of a composite of paraffin and graphite was tested to determine its thermal properties. Tests were conducted with a differential scanning calorimeter (DSC) and allowed the determination of the melting and solidification characteristics, latent heat, specific heat at melting and solidification, and thermal conductivity of the composite. The results of the study showed an increase in thermal conductivity by a factor of 4 when the mass fraction of the graphite in the composite was increased to 16.5%. The specific heat of the composite PCM (i.e., CPCM) decreased as the thermal conductivity increased, while the latent heat remained the same as the PCM component. In addition, the phase transition temperature was not influenced by the addition of expanded graphite. To explore the feasibility of the CPCM for practical applications, a numerical solution of the phase change transition of a small cylinder was derived. Finally, based on the properties obtained in DSC, a numerical simulation for a known volume of CPCM in a water tank was produced and indicated a reduction in solidification time by a factor of six.

Analysis and Design of a Paraffin/Graphite Composite PCM Integrated in a Thermal Storage Unit

2010 ◽  
Vol 132 (4) ◽  
Author(s):  
R. Pokhrel ◽  
J. E. González ◽  
T. Hight ◽  
T. Adalsteinsson
Keyword(s):  
Phase Transition ◽  
Thermal Conductivity ◽  
Transition Temperature ◽  
Energy Storage ◽  
Phase Change ◽  
Specific Heat ◽  
Latent Heat ◽  
Phase Transition Temperature ◽  
Thermal Storage ◽  
Melting And Solidification

The addition of latent heat storage systems in solar thermal applications has several benefits including volume reduction in storage tanks and maintaining the temperature range of the thermal storage. A phase change material (PCM) provides high energy storage density at a constant temperature corresponding to its phase transition temperature. In this paper, a high temperature PCM (melting temperature of 80°C) made of a composite of paraffin and graphite was tested to determine its thermal properties. Tests were conducted with a differential scanning calorimeter and allowed the determination of the melting and solidification characteristics, latent heat, specific heat at melting and solidification, and thermal conductivity of the composite. The results of the study showed an increase in thermal conductivity by a factor of 4 when the mass fraction of the graphite in the composite was increased to 16.5%. The specific heat of the composite PCM (CPCM) decreased as the thermal conductivity increased, while the latent heat remained the same as the PCM component. In addition, the phase transition temperature was not influenced by the addition of expanded graphite. To explore the feasibility of the CPCM for practical applications, a numerical solution of the phase change transition of a small cylinder was derived. Finally, a numerical simulation and the experimental results for a known volume of CPCM indicated a reduction in solidification time by a factor of 6. The numerical analysis was further explored to indicate the optimum operating Biot number for maximum efficiency of the composite PCM thermal energy storage.

Preparation of Expanded Perlite-Based Binary Eutectic Composite of Phase Change Heat Storage Materials

2011 ◽  
Vol 383-390 ◽  
pp. 2889-2893
Author(s):  
Bao Yun Zhang ◽  
Chang Mei Jiao ◽  
Peng Wang ◽  
Long Jiang ◽  
Bao Hua Ji ◽  
...  
Keyword(s):  
Phase Transition ◽  
Transition Temperature ◽  
Phase Change ◽  
Latent Heat ◽  
Phase Transition Temperature ◽  
Phase Change Materials ◽  
Vacuum Impregnation ◽  
Expanded Perlite ◽  
Good Thermal Stability ◽  
Binary Eutectic

The binary eutectic of lauric acid-stearic acid / expanded perlite composite phase change materials (PCM) was prepared using the method of vacuum impregnation. The structures and properties of this composite PCM were characterized by FT-IR, SEM, DSC and TG analysis. The results showed that the binary eutectic of fatty acid had been composed with porous skeleton expanded perlite completely in a physical method, the phase transition temperature of composite PCM was about 33.0 °C and latent heat was 131.3 J/g. it had a good thermal stability after 100 times of recycling and gave the phase transition temperature 33.5 °C and the latent heat of 128.1 J/g respectively.

Sunlight-Activated Phase Change Materials for Controlled Heat Storage and Triggered Release

2021 ◽  
Author(s):  
Yuran Shi ◽  
Mihael Gerkman ◽  
Qianfeng Qiu ◽  
Shuren Zhang ◽  
Grace G. D. Han
Keyword(s):  
Phase Transition ◽  
Solar Radiation ◽  
Phase Change ◽  
Latent Heat ◽  
Photon Energy ◽  
Organic Phase ◽  
Phase Change Materials ◽  
Heat Storage ◽  
Triggered Release

We report the design of photo-responsive organic phase change materials that can absorb filtered solar radiation to store both latent heat and photon energy via simultaneous phase transition and photo-isomerization....

scholarly journals Effective Separation of a Water in Oil Emulsion from a Direct Contact Latent Heat Storage System

Energies ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 2264 ◽  
Author(s):  
Sebastian Ammann ◽  
Andreas Ammann ◽  
Rebecca Ravotti ◽  
Ludger Fischer ◽  
Anastasia Stamatiou ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Latent Heat ◽  
Direct Contact ◽  
Heat Storage ◽  
Storage System ◽  
Heat Transfer Fluid ◽  
Storage Unit ◽  
Latent Heat Storage ◽  
Oil Emulsion ◽  
Water In Oil Emulsion

The problem of emulsification between Phase Change Material (PCM) and Heat Transfer Fluid (HTF) in direct contact latent heat storage systems has been reported in various studies. This issue causes the PCM to flow out of the storage tank and crystallize at unwanted locations and thus presents a major limitation for the proper operation of such systems. These anomalies become more pronounced when high HTF flow rates are employed with the aim to achieve fast heat transfer rates. The goal of this paper is to find a method which will enable the fast separation of the formed emulsion and thus the uninterrupted operation of the storage unit. In this study, three separation methods were examined and the use of superhydrophobic filters was chosen as the best candidate for the demulsification of the PCM and HTF mixtures. The filter was produced by processing of a melamine sponge with different superhydrophobic adhesives and was tested with emulsions closely resembling the ones formed in a real direct contact setup. The superhydrophobic filter obtained, was able to separate the emulsions effectively while presenting a very high permeability (up to 1,194,980 kg h−1 m−2 bar−1). This is the first time the use of a superhydrophobic sponge has been investigated in the context of demulsification in direct contact latent heat storage.

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