Preparation of Expanded Graphite and Fly Ash Base High Temperature Compound Phase Transition Heat Absorption Material and Its Application in Building Temperature Regulation

2020 ◽  
Vol 12 (6) ◽  
pp. 829-841
Author(s):  
Zhipeng Huo ◽  
Yuan Bai ◽  
Xiangyu Li
Keyword(s):  
Phase Transition ◽  
High Temperature ◽  
Phase Change ◽  
Temperature Regulation ◽  
Expanded Graphite ◽  
Analytical Techniques ◽  
Thermal Storage ◽  
Building Product ◽  
Storage Product ◽  
Composite Product

In this study, the product substance was pretreated with coal excrement as a raw product substance. Taking expanded graphite and paraffin as phase change product substances, expanded graphite and paraffin or coal excrement base high temperature compound phase transition thermal storage product substance were prepared by mixed sintering method. Firstly, the sintering mechanism of the composite should be deduced. In addition, XRD, TG-DSC and other analytical techniques were used to characterize the morphology and physical character of the product substances. In order to test the temperature regulation ability of the product substance, the composite product substance was fused with cement. The cement block added with composite product substance was taken as the research object, verify the performance of compound phase transition product substance on temperature regulation. In the experimental procedure, when phase change product substances' the proportion was less than 60%, the high temperature compound phase transition thermal storage product substances prepared were well-formed and had good crystallography, and the green body' various tissues were densely distributed. When the paraffin content was above 35 wt%, the external density, compressive strength, and cement blocks' thermal conductivity added with composite product substances increased significantly compared with ordinary expanded perlite cement blocks, which was suitable for building product substances' requirements. When the paraffin content reached 38 wt%, a temperature difference of 19.2 °C to 26.1 °C appeared in the composite product substance' corresponding cube space, indicating that room temperature can be adjusted by adding a certain phase change product substance.

Microencapsulation of Al-Zn alloy as phase change materials for high-temperature thermal storage application

2021 ◽  
pp. 131208
Author(s):  
Qinglin Li ◽  
Xiaodong Ma ◽  
Xiaoyu Zhang ◽  
Jiqiang Ma ◽  
Xiaowu Hu ◽  
...  
Keyword(s):  
High Temperature ◽  
Phase Change ◽  
Phase Change Materials ◽  
Thermal Storage ◽  
Zn Alloy

Heat Transfer Enhancement of Phase Change Materials (PCMs) in Low and High Temperature Thermal Storage by Using Porous Materials

2010 ◽  
Author(s):  
C. Y. Zhao ◽  
D. Zhou ◽  
Z. G. Wu
Keyword(s):  
Heat Transfer ◽  
High Temperature ◽  
Phase Change ◽  
Porous Materials ◽  
Phase Change Materials ◽  
Heat Transfer Performance ◽  
Expanded Graphite ◽  
Metal Foams ◽  
Transfer Performance ◽  
Solid Liquid

In this paper the solid/liquid phase change heat transfer in porous materials (metal foams and expanded graphite) at low and high temperatures is experimentally investigated, in an attempt to examine the feasibility of using metal foams to enhance the heat transfer capability of phase change materials for use with both the low and high temperature thermal energy storage systems. In this research, the organic commercial paraffin wax and inorganic hydrate calcium chloride hydrate salts were employed as the low-temperature materials, while the sodium nitrate is used as the high-temperature PCM in the experiment. The heat transfer characteristics of these PCMs embedded with open-cell metal foams were studied experimentally. The composites of paraffin and expanded graphite with different graphite mass ratios, namely, 3%, 6% and 9%, were also made and the heat transfer performances of these composites were tested and compared with metal foams. Overall metal foams can provide better heat transfer performance than expanded graphite due to their continuous inter-connected structures. But the porous materials can suppress the natural convection effect in liquid zone, particularly for the PCMs with low viscosities, thereby leading to the different heat transfer performance at different regimes (solid, solid/liquid and liquid regions). This implies that the porous materials don’t necessarily mean they can always enhance heat transfer in every regime.

Eutectic Na2CO3–NaCl salt: A new phase change material for high temperature thermal storage

2016 ◽  
Vol 152 ◽  
pp. 155-160 ◽  
Author(s):  
Yifeng Jiang ◽  
Yanping Sun ◽  
Ming Liu ◽  
Frank Bruno ◽  
Sean Li
Keyword(s):  
High Temperature ◽  
Phase Change ◽  
Phase Change Material ◽  
Thermal Storage ◽  
Change Material ◽  
New Phase

Research on Expanded Graphite/Nitrate High-Temperature Composite Phase Change Materials

2015 ◽  
Vol 740 ◽  
pp. 11-14 ◽  
Author(s):  
Yue Feng Li
Keyword(s):  
Thermal Conductivity ◽  
High Temperature ◽  
Phase Change ◽  
Phase Change Materials ◽  
Water Solution ◽  
Expanded Graphite ◽  
High Temperature Phase ◽  
Temperature Phase ◽  
Solidification Temperature ◽  
Saturated Water Solution

In order to enhance the thermal conductivity of high-temperature phase change materials (PCMs), expanded graphite (EG) /NaNO3-LiNO3 composite was prepared by the method of eutectic aqueous solution infiltration porous structure of EG. The composites with an EG amount of 10%, 20% and 30% were prepared in the similar way. The results proved that the eutectic was an excellent PCM, for its melting (solidification) temperature was 193.7 (191.7) °C, and its latent heat was 272.6(262.6) kJ/kg. With the increasing in graphite amount, the thermal conductivity of the composite was found to progressively increase with intensifications up to 10. We can conclude that the saturated water solution method was a simple and effective way to strengthen the thermal conductivity of the eutectic.

scholarly journals Effects of Total Thermal Balance on the Thermal Energy Absorbed or Released by a High-Temperature Phase Change Material

Molecules ◽  
2021 ◽  
Vol 26 (2) ◽  
pp. 365
Author(s):  
Suset Rodríguez-Alemán ◽  
Ernesto M. Hernández-Cooper ◽  
Rolando Pérez-Álvarez ◽  
José A. Otero
Keyword(s):  
Phase Transition ◽  
High Temperature ◽  
Phase Change ◽  
Thermodynamic Equilibrium ◽  
Thermal Energy ◽  
Phase Change Materials ◽  
High Temperature Phase ◽  
Thermal Balance ◽  
Temperature Phase ◽  
Solid Interface

Front tracking and enthalpy methods used to study phase change processes are based on a local thermal energy balance at the liquid–solid interface where mass accommodation methods are also used to account for the density change during the phase transition. Recently, it has been shown that a local thermal balance at the interface does not reproduce the thermodynamic equilibrium in adiabatic systems. Total thermal balance through the entire liquid–solid system can predict the correct thermodynamic equilibrium values of melted (solidified) mass, system size, and interface position. In this work, total thermal balance is applied to systems with isothermal–adiabatic boundary conditions to estimate the sensible and latent heat stored (released) by KNO3 and KNO3/NaNO3 salts which are used as high-temperature phase change materials. Relative percent differences between the solutions obtained with a local thermal balance at the interface and a total thermal balance for the thermal energy absorbed or released by high-temperature phase change materials are obtained. According to the total thermal balance proposed, a correction to the liquid–solid interface dynamics is introduced, which accounts for an extra amount of energy absorbed or released during the phase transition. It is shown that melting or solidification rates are modified by using a total thermal balance through the entire system. Finally, the numerical and semi-analytical methods illustrate that volume changes and the fraction of melted (solidified) solid (liquid) estimated through a local thermal balance at the interface are not invariant in adiabatic systems. The invariance of numerical and semi-analytical solutions in adiabatic systems is significantly improved through the proposed model.

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