Experimental and Numerical Investigation of Melting Process in PCM Storage

2015 ◽  
Author(s):  
Makoto Shibahara
Keyword(s):  
Numerical Simulation ◽  
Phase Change ◽  
Power Plants ◽  
Waste Heat ◽  
Solid Phase ◽  
Liquid Fraction ◽  
Melting Process ◽  
Shunt Resistance ◽  
Experimental Apparatus ◽  
Cartridge Heater

Thermal energy storage (TES) technologies have been developed using Phase Change Materials (PCM) at various power plants to utilize waste heat sources. The melting process of PCM has been investigated experimentally and numerically to construct a fundamental database of TES systems. D-Mannitol was selected as a PCM for medium TES systems in this study. The experimental apparatus consisted of the cartridge heater, thermocouples, test tube, acryl tube, vacuum pump, pressure indicator, volt slider and shunt resistance. The temperatures near the cartridge heater were measured by K-type thermocouples. The heat inputs were ranged from 10W to 15W. As a result, temperature of D-mannitol increased with time linearly under the solid state until the fusion temperature. When D-mannitol changed from the solid phase to the liquid phase, temperatures remained constantly due to the latent heat. Moreover, the numerical simulation was conducted using the commercial CFD code, ANSYS FLUENT. As a result of the numerical simulation, it was understood that the melting process was affected by the natural convection at the inner wall. As the heat flux of the cartridge heater input from the inner wall, the liquid fraction increased from the inner wall to the outer wall. The numerical result was compared with the experimental data. It was understood that the temperature of numerical simulation was approximately consistent with that of the experiment during the phase change process.

scholarly journals Numerical simulation of a phase change material melting process

2019 ◽  
Vol 112 ◽  
pp. 01010
Author(s):  
Dorin Stanciu ◽  
Camelia Stanciu ◽  
Valentin Apostol ◽  
Horatiu Pop
Keyword(s):  
Numerical Simulation ◽  
Phase Change ◽  
Phase Change Materials ◽  
Liquid Fraction ◽  
Melting Process ◽  
Heat Transfer Fluid ◽  
External Diameter ◽  
Storage Solutions ◽  
Wide Range ◽  
Change Material

Storage processes are usually integrated in solar energy systems applications due to daily variation of this energy source availability. Among different thermal storage solutions, phase change materials (PCM) lately became more extensively used covering a wide range of operating temperatures. In this regard, a numerical simulation of a PCM melting process is performed under ANSYS CFD environment. A particular configuration is considered consisting in a 2m length annular tube having a 5.48 cm external diameter. The tube is filled with paraffin chosen as PCM. A concentric interior tube of 2.54 cm diameter is used for transporting the heat transfer fluid (HTF) from the solar collector. Heat is transferred through the 1 mm thick pipe wall to the PCM placed all around the HTF tube. The numerical results reveal the melting process of the PCM at different instances and tube sections. The time variation of the PCM liquid fraction is emphasized. The results describe the dynamic behavior of a PCM melting process and might be further integrated in any solar power plant storage charging process simulation.

Numerical simulation of several impacting ceramic droplets with liquid/solid phase change

2015 ◽  
Vol 268 ◽  
pp. 272-277 ◽  
Author(s):  
Cédric Le Bot ◽  
Stéphane Vincent ◽  
Erick Meillot ◽  
Frédéric Sarret ◽  
Jean-Paul Caltagirone ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Phase Change ◽  
Solid Phase

Numerical Simulation of Two Phase Change Materials Melting Process

2014 ◽  
Vol 1049-1050 ◽  
pp. 94-100
Author(s):  
Bo Bo Zhang ◽  
Yu Ming Xing ◽  
Qiang Sheng
Keyword(s):  
Numerical Simulation ◽  
Energy Storage ◽  
Temperature Distribution ◽  
Phase Change ◽  
Latent Heat ◽  
Control Function ◽  
Melting Process ◽  
Thermal Control ◽  
Heat Energy ◽  
Two Phase

Phase change thermal control technology has gained increasing focus as an emerging technology for the thermal control of spacecraft. This literature focused on melting process inside a latent heat energy storage filled with phase change material (PCM) by numerical simulation. A matrix-based enthalpy porosity theory in a three-dimensional finite volume discretization is simulated. The temperature distribution during the melting process of PCM Cerrolow-136 and CH3COONa·3H2O is obtained, based on which the thermal control function and energy storage capacity is compared. The results show that Cerrolow-136 has better performance. In different states of phase change, the temperature distribution of Cerrolow-136 is fairly uniform. Thermal control face's temperature of Cerrolow-136 is closer to phase transition temperature. In the same heat flux of 3000 W/m2, The whole process of thermal control temperature getting to 80°C for Cerrolow-136 is longer. Cerrolow-136, for its excellent characteristics, has potentially broad application in the fields of latent heat energy storage and space vehicle electronics.

scholarly journals NUMERICAL ANALYSIS OF LIQUID FRACTION AND HEAT FLUX IN THE SOLIDIFICATION PROCESS OF ERYTHRITOL IN SPHERES

2017 ◽  
Vol 16 (1) ◽  
pp. 24
Author(s):  
J. H. N. Ehms ◽  
F. A. Bodnar ◽  
I. D. R. dos Santos ◽  
R. D. C. Oliveski
Keyword(s):  
Heat Flux ◽  
Numerical Model ◽  
Phase Change ◽  
Volume Fraction ◽  
Waste Heat ◽  
Liquid Fraction ◽  
Numerical Models ◽  
Solidification Process ◽  
Energy Performance ◽  
High Heat Flux

The demand for renewable energy resources and the need for the development of components which increase how it collects, transforms, stores and distributes this energy, emphasizes the importance of improving current technological systems to meet these demands. Phase change materials (PCM) offer great potential in this area. as they can increase energy efficiency in thermal systems as well as save energy by storing solar energy or waste heat from industrial processes, which is made possible by the high amount of energy stored per mass and volume unit, with low temperature variation. Therefore, it is of high importance that the suggested mathematical and numerical models are capable of analyzing its energy performance. The present work uses a mathematical and numerical model of Computational Fluid Dynamics (CFD), capable of reproducing the solidification process of erythritol in spheres of 10, 20, 30 and 40 mm diameters, with temperature differences of 10, 15, 20, 25, 30 and 40 K between the sphere wall and the phase change temperature of the material. The problem is considered two- dimensional and transient. The model consists of mass, energy, momentum and volume fraction equations. The mathematical and numerical model is validated with experimental results from the literature, presenting good agreement between them. After space and time discretization tests, we analyze liquid fraction over time and heat flux at the sphere wall. The results show that liquid fraction suffers a strong reduction in the beginning of the solidification process due to the high heat flux in the early stages. As the solid layer near the wall increases, it causes an increase in thermal resistance, causing a significant reduction in heat flux.

scholarly journals Melting of a phase change material in a horizontal annulus with discrete heat sources

2015 ◽  
Vol 19 (5) ◽  
pp. 1733-1745 ◽  
Author(s):  
Hooshyar Mirzaei ◽  
Abdolrahman Dadvand ◽  
Mohammad Mastiani ◽  
Seyed Sebti ◽  
Sina Kashani
Keyword(s):  
Energy Storage ◽  
Phase Change ◽  
Phase Change Material ◽  
Liquid Fraction ◽  
Outer Cylinder ◽  
Melting Process ◽  
Cylinder Wall ◽  
Heat Sources ◽  
Discrete Heat Sources ◽  
Change Material

Phase change materials have found many industrial applications such as cooling of electronic devices and thermal energy storage. This paper investigates numerically the melting process of a phase change material in a two-dimensional horizontal annulus with different arrangements of two discrete heat sources. The sources are positioned on the inner cylinder of the annulus and assumed as constant-temperature boundary conditions. The remaining portion of the inner cylinder wall as well as the outer cylinder wall is considered to be insulated. The emphasis is mainly on the effects of the arrangement of the heat source pair on the fluid flow and heat transfer features. The governing equations are solved on a non-uniform O type mesh using a pressure-based finite volume method with an enthalpy porosity technique to trace the solid and liquid interface. The results are obtained at Ra=104 and presented in terms of streamlines, isotherms, melting phase front, liquid fraction and dimensionless heat flux. It is observed that, depending on the arrangement of heat sources, the liquid fraction increases both linearly and non-linearly with time but will slow down at the end of the melting process. It can also be concluded that proper arrangement of discrete heat sources has the great potential in improving the energy storage system. For instance, the arrangement C3 where the heat sources are located on the bottom part of the inner cylinder wall can expedite the melting process as compared to the other arrangements.

Numerical Study of Phase Change of PCM in Spherical Cavities

2017 ◽  
Vol 372 ◽  
pp. 21-30 ◽  
Author(s):  
Fábio Faistauer ◽  
Petros Rodrigues ◽  
Rejane de Césaro Oliveski
Keyword(s):  
Phase Change ◽  
Melting Temperature ◽  
Wall Temperature ◽  
Phase Change Materials ◽  
Numerical Study ◽  
Liquid Fraction ◽  
Fluid Dynamic ◽  
Melting Process ◽  
Constant Wall Temperature ◽  
Spherical Cavities

This work presents a numerical study of the phase change process of PCM (Phase Change Materials) stored in spherical cavities. The numerical model is two-dimensional and it is composed by the equations of conservation of mass, momentum, energy and volumetric fraction, which are modeled using the enthalpy-porosity technique. The computational mesh is tetrahedral, with refinements on regions that have large thermic and fluid dynamic gradients. The numeric model was validated with result from literature. It was studied the melting process of PCM RT35, RT 55 and RT 82 in spherical cavity with constant wall temperature. Four diameters of spheres D were used (40, 60, 80 and 100 mm) and three temperature differences ΔT (10, 20 and 30 oC) between the wall temperature and the melting temperature of the PCM. Liquid fraction results from the 36 cases studied are presented. It was observed that the time required to reach a certain liquid fraction increases with the diameter and reduces with the increment of ΔT, being possible to predict the fusion time by knowing the characteristic length of the sphere. The largest percentage reduction of the fusion time was obtained with ΔT = 10 oC – 20 oC for all the D considered. The shortest fusion time was obtained with the largest ΔT combined with the smallest D. It is possible to see the dependence of the liquid fraction results in relation with the PCM properties and the its independence in relation its melting temperature, since all the PCM studied presented equal fusion time for the same ΔT and D.

Investigation of the Heat Transfer Process in a PCM During Melting Phase

2014 ◽  
Author(s):  
Mohammad Bashar ◽  
Kamran Siddiqui
Keyword(s):  
Heat Transfer ◽  
Phase Change ◽  
Thermal Energy ◽  
Transfer Process ◽  
Phase Change Materials ◽  
Waste Heat ◽  
Liquid Fraction ◽  
Local Heat Transfer ◽  
Heat Transfer Process ◽  
Interface Temperature

Thermal energy storage systems are gaining significance due to their potential use to store renewable energy and waste heat. Phase change materials (PCMs) are considered to be an efficient way to store thermal energy. However, the heat transfer process during the phase change is not well understood. We report on an experimental study conducted to investigate the heat transfer process in a PCM during melting phase. A PCM storage system subjected to bottom heating from a horizontal heated cylinder was considered using wax as the PCM. An imaging technique was used to capture the movement of the solid-liquid interface. Temperature was measured at multiple locations to quantify the heat transfer process. The interface was found to move with a relatively uniform velocity throughout the melting process however, the heat transfer rate was significantly enhanced in the melted (liquid) phase. The local heat transfer coefficient was found to decrease with an increase in the liquid fraction.

Sign in / Sign up

Export Citation Format

Share Document