scholarly journals Numerical study on solidification heat transfer of spherical composite phase change capsule with high thermal conductivity

AIP Advances ◽  
2018 ◽  
Vol 8 (12) ◽  
pp. 125125 ◽  
Author(s):  
Xiaoli Dai ◽  
Xiaoyan Wu ◽  
Fei Tian
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Phase Change ◽  
Numerical Study ◽  
High Thermal Conductivity

NATURAL CONVECTION HEAT TRANSFER FROM A DISCRETE HEAT SOURCE COUPLED WITH CONDUCTION DOMINATED PHASE CHANGE

1998 ◽  
Vol 22 (3) ◽  
pp. 269-289
Author(s):  
M. Lacroix
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Steady State ◽  
Natural Convection ◽  
Thermal Diffusivity ◽  
Heat Source ◽  
Phase Change ◽  
Numerical Study ◽  
Thermal Conductivity Ratio ◽  
Discrete Heat Source

A numerical study has been conducted for the heat transfer from a discrete heat source by natural convection in air above coupled with conduction dominated melting of a phase change material (PCM) below via a wall of finite thermal diffusivity. Results indicate that the presence of a PCM layer underneath the wall significantly delays the temperature rise of the heat source. The time delay increases as the thermal diffusivity of the wail material decreases and as the thickness of the PCM layer increases. For high thermal conductivity wall materials [Formula: see text] the steady state heat source temperatures are similar and independent of the PCM layer. On the other hand, for [Formula: see text], the steady state temperatures are higher and dependent on the thickness of the PCM layer. A correlation is proposed in terms of the thickness of the PCM layer and the thermal conductivity ratio of the wall.

NUMERICAL STUDY ON THE THERMAL PERFORMANCE OF A PHASE CHANGE HEAT EXCHANGER (PCHE) WITH INNOVATIVE FRACTAL TREE-SHAPED FINS

Fractals ◽  
2020 ◽  
Vol 28 (05) ◽  
pp. 2050083
Author(s):  
XIANGDONG LIU ◽  
FEIFAN LIU ◽  
QIAOBO DAI ◽  
FENG YAO ◽  
TIANJUN ZENG ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Heat Exchanger ◽  
Phase Change ◽  
Solidification Front ◽  
Numerical Study ◽  
Low Cost ◽  
Pure Copper ◽  
Evaluation Criteria ◽  
Temperature Response ◽  
High Thermal Conductivity

For alleviating energy shortage and environmental problems, it is of great importance to improve the energy charging and discharging efficiency of thermal energy storage systems. In this context, an innovative phase change heat exchanger (PCHE) with fractal tree-shaped fins is presented in this paper. A numerical investigation of the solidification behaviors in the PCHE with fractal tree-shaped fins is conducted. The dynamic temperature response and the solidification front evolution in the PCHE are analyzed and discussed. Furthermore, two evaluation criteria, including total solidification time and energy charging efficiency, are introduced to quantitatively study the effect of fin material on the solidification heat transfer characteristics. The results indicate that the fractal tree-shaped fin leads to a uniform temperature distribution of phase change material (PCM). The temperature response of fin is faster than that of PCM due to its high thermal conductivity. Moreover, the fractal tree-shaped fin breaks the restriction of gradually forward fashion of solidification front in the traditional PCHE and dramatically improves the energy discharging performance. The material of fractal tree-shaped fins is an essential factor affecting the solidification performance of the PCHE. The energy discharging performance of PCHE with pure copper fins is the best, whereas that with cupronickel fins is the worst. However, from the perspective of practical application, aluminum is the best potential alternative because of its relatively high thermal conductivity, lighter weight, and low cost.

scholarly journals High Temperature Thermal Energy Storage Utilizing Metallic Phase Change Materials and Metallic Heat Transfer Fluids

2013 ◽  
Vol 135 (3) ◽  
Author(s):  
Johannes P. Kotzé ◽  
Theodor W. von Backström ◽  
Paul J. Erens
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Energy Storage ◽  
Phase Change ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Phase Change Materials ◽  
Metallic Phase ◽  
High Thermal Conductivity ◽  
Heat Transfer Fluids

Cost and volume savings are some of the advantages offered by the use of latent heat thermal energy storage (TES). Metallic phase change materials (PCMs) have high thermal conductivity, which relate to high charging and discharging rates in TES system, and can operate at temperatures exceeding 560 °C. In the study, a eutectic aluminium–silicon alloy, AlSi12, is identified as a good potential PCM. AlSi12 has a melting temperature of 577 °C, which is above the working temperature of regular heat transfer fluids (HTFs). The eutectic sodium–potassium alloy (NaK) is identified as an ideal HTF in a storage system that uses metallic PCMs. A concept is presented that integrates the TES-unit and steam generator into one unit. As NaK is highly reactive with water, the inherently high thermal conductivity of AlSi12 is utilized in order to create a safe concept. As a proof of concept, a steam power-generating cycle was considered that is especially suited for a TES using AlSi12 as PCM. The plant was designed to deliver 100 MW with 15 h of storage. Thermodynamic and heat transfer analysis showed that the concept is viable. The analysis indicated that the cost of the AlSi12 storage material is 14.7 US$per kWh of thermal energy storage.

scholarly journals Numerical Simulation of the Impact of the Heat Source Position on Melting of a Nano-Enhanced Phase Change Material

Nanomaterials ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1425
Author(s):  
Tarek Bouzennada ◽  
Farid Mechighel ◽  
Kaouther Ghachem ◽  
Lioua Kolsi
Keyword(s):  
Heat Transfer ◽  
Phase Change ◽  
Phase Change Material ◽  
Numerical Study ◽  
Melting Rate ◽  
Heat Transfer Fluid ◽  
Commercial Code ◽  
Tube Position ◽  
The Impact ◽  
Change Material

A 2D-symmetric numerical study of a new design of Nano-Enhanced Phase change material (NEPCM)-filled enclosure is presented in this paper. The enclosure is equipped with an inner tube allowing the circulation of the heat transfer fluid (HTF); n-Octadecane is chosen as phase change material (PCM). Comsol-Multiphysics commercial code was used to solve the governing equations. This study has been performed to examine the heat distribution and melting rate under the influence of the inner-tube position and the concentration of the nanoparticles dispersed in the PCM. The inner tube was located at three different vertical positions and the nanoparticle concentration was varied from 0 to 0.06. The results revealed that both heat transfer/melting rates are improved when the inner tube is located at the bottom region of the enclosure and by increasing the concentration of the nanoparticles. The addition of the nanoparticles enhances the heat transfer due to the considerable increase in conductivity. On the other hand, by placing the tube in the bottom area of the enclosure, the liquid PCM gets a wider space, allowing the intensification of the natural convection.

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