Computational Investigation of Thermal Interaction Phenomena Between Two Adjacent Spheres Filled with Different Phase Change Materials (PCMs)

2017 ◽  
Vol 25 (04) ◽  
pp. 1750033 ◽  
Author(s):  
Khouiled Rachedi ◽  
Abdel Illah Nabil Korti
Keyword(s):  
Natural Convection ◽  
Phase Change ◽  
Phase Change Materials ◽  
Computational Study ◽  
Heat Transfer Fluid ◽  
Inlet Temperature ◽  
Thermal Interaction ◽  
Computational Investigation ◽  
Energy Storage Applications ◽  
Interaction Phenomena

One of the discussed techniques in improving the performance of latent thermal energy storage applications is to use different phase change materials (PCMs) encapsulated in spherical nodules. However, the large number of spheres used in the storage applications pushes the researchers to neglecting the natural convection effect inside spheres. Consequently, they cannot observe the real thermal interaction effect between spheres. The objective of this work is to carry out a computational study on the thermal behavior of two adjacent different PCMs inside aluminum spherical capsules and taking into account the natural convection effect inside the spheres. Water is used as heat transfer fluid (HTF) at constant inlet temperature. The study shows that for the HTF inlet velocity lower than 10[Formula: see text][Formula: see text]m/s, the thermal interaction between two adjacent different PCMs cannot be neglected. However, the thermal interaction appears more clearly in the discharging mode. The thermal interaction can accelerate the discharging of one of the PCMs by reducing the discharging of the other one.

Numerical Model for Storage Systems Based on Phase-Change Materials

2011 ◽  
Author(s):  
Adriano Sciacovelli ◽  
Vittorio Verda ◽  
Francesco Colella
Keyword(s):  
Heat Transfer ◽  
Phase Change ◽  
Phase Change Materials ◽  
Storage Systems ◽  
Numerical Procedure ◽  
Thermal Storage ◽  
Operating Conditions ◽  
Heat Transfer Fluid ◽  
Inlet Temperature ◽  
Technical Problems

Phase-change materials (PCM) are particularly promising for thermal storage in various energy plants as solar plants, district heating, heat pumps, etc. mainly because of the possibility to reduce the volume of storage tanks, but also because the problems related with thermal stratification are considerably reduced. On the other hand, research is necessary in order to address technical problems, mainly related to the heat transfer in the medium, which needs to be enhanced in order to achieve reasonable charging and discharging processes. The present paper describes the application of computational fluid-dynamics (CFD) for the analysis of PCM thermal storage systems. The numerical analysis is directed at understanding the role of buoyancy-driven convection during constrained solidification and melting inside a shell-and-tube geometry. The 2D model is based on a finite-volume numerical procedure that adopts the enthalpy method to take in account the phase change phenomenon. The time-dependent simulations show the melting phase front and melting fraction of the PCM and incorporate the fluid flow in the liquid phase. The obtained temperature profiles are compared to a set of experimental data available in the literature. The results show that during the melting process natural convection within the PCM has non negligible effects on the behavior of the system. The numerical simulations of the solidification process show that the increasing solid fraction of the PCM inhibits the buoyancy in the remaining liquid portion of the phase-change-material. Furthermore, the paper discusses the effects on the phase-change processes of the main operating conditions, including inlet temperature and mass flow rate of the heat transfer fluid.

scholarly journals Reviewing the Exergy Analysis of Solar Thermal Systems Integrated with Phase Change Materials

Energies ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 724
Author(s):  
Macmanus Chinenye Ndukwu ◽  
Lyes Bennamoun ◽  
Merlin Simo-Tagne
Keyword(s):  
Phase Change ◽  
Phase Change Materials ◽  
Second Law Of Thermodynamics ◽  
Heat Transfer Fluid ◽  
Solar Still ◽  
Thermal Systems ◽  
Solar Systems ◽  
Exergy Balance ◽  
Change Material

The application of thermal storage materials in solar systems involves materials that utilize sensible heat energy, thermo-chemical reactions or phase change materials, such as hydrated salts, fatty acids paraffin and non-paraffin like glycerol. This article reviews the various exergy approaches that were applied for several solar systems including hybrid solar water heating, solar still, solar space heating, solar dryers/heaters and solar cooking systems. In fact, exergy balance was applied for the different components of the studied system with a particular attention given to the determination of the exergy efficiency and the calculation of the exergy during charging and discharging periods. The influence of the system configuration and heat transfer fluid was also emphasized. This review shows that not always the second law of thermodynamics was applied appropriately during modeling, such as how to consider heat charging and discharging periods of the tested phase change material. Accordingly, the possibility of providing with inappropriate or not complete results, was pointed.

Natural Convection in an Enclosure With Blend of Micro Encapsulated Phase Change Materials

2013 ◽  
Author(s):  
Yasmin Khakpour ◽  
Jamal Seyed-Yagoobi
Keyword(s):  
Heat Transfer ◽  
Thermal Expansion ◽  
Natural Convection ◽  
Phase Change ◽  
Latent Heat ◽  
Phase Change Materials ◽  
Numerical Study ◽  
Pure Water ◽  
Operating Conditions ◽  
Effective Density

This numerical study investigates the effect of using a blend of micro-encapsulated phase change materials (MEPCMs) on the heat transfer characteristics of a liquid in a rectangular enclosure driven by natural convection. A comparison has been made between the cases of using single component MEPCM slurry and a blend of two-component MEPCM slurry. The natural convection is generated by the temperature difference between two vertical walls of the enclosure maintained at constant temperatures. Each of the two phase change materials store latent heat at a specific range of temperatures. During phase change of the PCM, the effective density of the slurry varies. This results in thermal expansion and hence a buoyancy driven flow. The effects of MEPCM concentration in the slurry and changes in the operating conditions such as the wall temperatures compared to that of pure water have been studied. The MEPCM latent heat and the increased volumetric thermal expansion coefficient during phase change of the MEPCM play a major role in this heat transfer augmentation.

scholarly journals Enhancement of the Thermal Energy Storage Using Heat-Pipe-Assisted Phase Change Material

Energies ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 6176 ◽  
Author(s):  
Hamidreza Behi ◽  
Mohammadreza Behi ◽  
Ali Ghanbarpour ◽  
Danial Karimi ◽  
Aryan Azad ◽  
...  
Keyword(s):  
Energy Storage ◽  
Phase Change ◽  
Heat Pipe ◽  
Latent Heat ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Phase Change Materials ◽  
Liquid Fraction ◽  
Energy Storage Applications ◽  
Change Material

Usage of phase change materials’ (PCMs) latent heat has been investigated as a promising method for thermal energy storage applications. However, one of the most common disadvantages of using latent heat thermal energy storage (LHTES) is the low thermal conductivity of PCMs. This issue affects the rate of energy storage (charging/discharging) in PCMs. Many researchers have proposed different methods to cope with this problem in thermal energy storage. In this paper, a tubular heat pipe as a super heat conductor to increase the charging/discharging rate was investigated. The temperature of PCM, liquid fraction observations, and charging and discharging rates are reported. Heat pipe effectiveness was defined and used to quantify the relative performance of heat pipe-assisted PCM storage systems. Both experimental and numerical investigations were performed to determine the efficiency of the system in thermal storage enhancement. The proposed system in the charging/discharging process significantly improved the energy transfer between a water bath and the PCM in the working temperature range of 50 °C to 70 °C.

scholarly journals Performance Assessment of Phase Change Materials Integrated with Building Envelope for Heating Application in Cold Locations

2021 ◽  
Vol 1 (1) ◽  
pp. 7-14
Author(s):  
Qudama M. Q. Al-Yasiri ◽  
Márta Szabó
Keyword(s):  
Phase Change ◽  
Energy Saving ◽  
Phase Change Materials ◽  
Renewable Energy Sources ◽  
Building Energy ◽  
Building Envelope ◽  
Cold Climates ◽  
Building Energy Saving ◽  
Energy Storage Applications ◽  
Heating Loads

Phase change materials (PCMs) are increasingly investigated in the last years as successful in many thermal energy storage applications. In the building sector, PCMs are utilised to improve building efficiency by reducing cooling/heating loads and promoting renewable energy sources, such as solar energy. This paper shows the recent research works on integrating PCMs with building envelope for heating purposes. The main PCM categories and their main characteristics are presented, focusing on PCM types applied for building heating applications. The main methods adopted to incorporate PCMs with building elements and materials are mentioned, and the popular passive and active incorporation techniques are discussed. Lastly, the main contribution to building energy saving is discussed in terms of heating applications. The analysed studies indicated that all PCMs could improve the building energy saving in the cold climates by up to 44.16% regardless of their types and techniques. Several conclusions and recommendations are derived from the analysed studies that are believed to be a guideline for further research.

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