Study of the Melting Behavior in a PCM-Based Thermal Energy Storage

2015 ◽  
Author(s):  
Mohammad Bashar ◽  
Kamran Siddiqui
Keyword(s):  
Heat Transfer ◽  
Energy Storage ◽  
Heat Source ◽  
Phase Change ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Storage Systems ◽  
Renewable Energy Sources ◽  
Heat Transfer Process ◽  
Convective Cells

Thermal energy storages are becoming important due to their significance in energy conservation as well as for the uninterrupted supply of thermal energy from renewable energy sources. The latent heat-based thermal energy storage systems utilizing phase change material (PCM) are gaining much attention due to some inherent advantages compared to sensible heat-based storage systems. However, the heat transfer process associated with the phase change in a PCM is complex and not well understood. In the present study, the melting process in a PCM-based thermal storage is experimentally studied. Two different configurations of the heat source were considered; horizontal and U-tube heat sources. The results show that the heat source shape has a significant influence on the solid to liquid phase change process (melting). The results also show that for the horizontal heat source configuration, the solid-liquid interface has a wavy profile, which is attributed to the convective cells in the melted domain of the PCM. These convective cells also influence the heat transfer coefficient, which decreased with an increase in the melted fraction. In U-tube configuration, the heat is non-uniformly transferred to the PCM domain.

Effect of Fin Orientation on Melting Process in Horizontal Double Pipe Thermal Energy Storage Systems

2021 ◽  
pp. 1-16
Author(s):  
Nesrine Boulaktout ◽  
El-Hacène Mezaache ◽  
Mohamed Teggar ◽  
Müslüm Arici ◽  
K.A.R. Ismail ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Energy Storage ◽  
Phase Change ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Storage Systems ◽  
Melting Process ◽  
Storage Unit ◽  
Charging Time ◽  
Thermal Energy Storage Systems

Abstract Immersion of fins in latent heat thermal energy storage systems has been used as an influential approach to remedy the poor thermal conductivity of phase-change materials. Present paper numerically investigates heat transfer and phase change improvement by means of longitudinal fins in a shell and tube thermal energy storage unit. The main aim of this study is to investigate the effect of fin orientation on the performance of the storage unit. Six configurations of different fin numbers (2, 4 and 8 fins) and orientations (π/2, π/4, and π/8) are tested. For simulations, a 2D mathematical model incorporating the enthalpy-porosity method and finite volume techniques are established and solved by ANSYS-Fluent. The numerical predictions are successfully validated by comparison with experimental and numerical data from the literature. Heat transfer characteristics and melting process are analyzed through streamlines, isotherms, mean temperature, heat flux and heat transfer coefficient as well as transient melting front position and liquid fractions. Results show that orientation of fins has significant impact on the charging time for two cases (2 and 4 fins) whereas no significant reduction in charging time was obtained for the case of 8 fins. In case of utilizing 2 fins, a fin orientation of 0° (vertical fins) shortens the charging time by up to 2.5 folds compared to the horizontal fins (90°). These results could help designing efficient latent thermal energy storage units.

scholarly journals Investigation of the dynamic characteristics of a thermal energy storage unit filled with multiple phase change materials

2018 ◽  
Vol 22 (Suppl. 2) ◽  
pp. 527-533 ◽  
Author(s):  
Xiaoyan Li ◽  
Rongpeng Huang ◽  
Xinyue Miao ◽  
Xuelei Wang ◽  
Yabin Liu ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Energy Storage ◽  
Phase Change ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Phase Change Materials ◽  
Storage Systems ◽  
Heat Transfer Fluid ◽  
Energy Storage Systems ◽  
Thermal Energy Storage Systems

In order to improve the thermal performance of thermal energy storage systems, a packed bed thermal energy storage systems unit using spherical capsules filled with multiple phase change materials (multi-PCM) for use in conventional air-conditioning systems is presented. A 3-D mathematical model was established to investigate the charging characteristics of the thermal energy storage systems unit. The optimum proportion between the multi-PCM was identified. The effects of heat transfer fluid-flow rate and heat transfer fluid inlet temperature on the liquid phase change materials volume fraction, charging time and charging capacity of the thermal energy storage system unit are studied. The results indicate that the charging capacity of multi-PCM units is higher than that of the conventional single-PCM (HY-2). For proportions 0:1:0, 2:3:3, 3:2:3, 3:3:2, 4:1:3, and 4:2:2, the charging capacity decreases by approximately 24.84%, 14.69%, 6.47%, 3.82%, and 1.13%, respectively, compared to the 4:2:2 proportion. Moreover, decreasing the heat transfer fluid inlet temperature can obviously shorten the complete charging time of the thermal energy storage systems unit.

scholarly journals Optimum Placement of Heating Tubes in a Multi-Tube Latent Heat Thermal Energy Storage

Materials ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1232
Author(s):  
Mohammad Ghalambaz ◽  
Hayder I. Mohammed ◽  
Ali Naghizadeh ◽  
Mohammad S. Islam ◽  
Obai Younis ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Energy Storage ◽  
Taguchi Method ◽  
Phase Change ◽  
Latent Heat ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Storage Systems ◽  
Heat Transfer Fluid ◽  
Energy Storage Systems

Utilizing phase change materials in thermal energy storage systems is commonly considered as an alternative solution for the effective use of energy. This study presents numerical simulations of the charging process for a multitube latent heat thermal energy storage system. A thermal energy storage model, consisting of five tubes of heat transfer fluids, was investigated using Rubitherm phase change material (RT35) as the. The locations of the tubes were optimized by applying the Taguchi method. The thermal behavior of the unit was evaluated by considering the liquid fraction graphs, streamlines, and isotherm contours. The numerical model was first verified compared with existed experimental data from the literature. The outcomes revealed that based on the Taguchi method, the first row of the heat transfer fluid tubes should be located at the lowest possible area while the other tubes should be spread consistently in the enclosure. The charging rate changed by 76% when varying the locations of the tubes in the enclosure to the optimum point. The development of streamlines and free-convection flow circulation was found to impact the system design significantly. The Taguchi method could efficiently assign the optimum design of the system with few simulations. Accordingly, this approach gives the impression of the future design of energy storage systems.

scholarly journals FAZINIO VIRSMO MEDŽIAGOS CHARAKTERISTIKŲ ŠILUMOS KAUPIKLYJE SKAITINIS MODELIAVIMAS / SIMULATION OF THE PHASE CHANGE MATERIALS’ CHARACTERISTICS IN A THERMAL ENERGY STORAGE

2018 ◽  
Vol 10 (0) ◽  
pp. 1-7 ◽  
Author(s):  
Saulius Pakalka ◽  
Kęstutis Valančius ◽  
Giedrė Streckienė ◽  
Vaidvilė Ulbikaitė
Keyword(s):  
Heat Transfer ◽  
Energy Storage ◽  
Phase Change ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Phase Change Materials ◽  
Heat Transfer Process ◽  
Comsol Multiphysics ◽  
Storage Unit ◽  
Energy Storage Unit

In order to use efficiently residual, waste or renewable energy, the application of phase change materials (PCM) grows in building energy systems. At the same time, this poses new technological challenges in choosing specific materials, system design solutions, because it requires a specific knowledge of the heat transfer process during the phase change. The aim of the work is to investigate the heat transfer in a PCM based thermal energy storage unit using the COMSOL Multiphysics software. In the analysis, the properties of the material were evaluated during the phase change. This allowed to determine that the thermal conductivity of the material is of great importance for the intensification of heat transfer. In addition, the analysis of several points in the analyzed object revealed that the phase change does not occur in the surface layer of the PCM during the period under consideration. In order to avoid that, additional solutions such as integrating heat-conductive materials into the PCM or increasing the surface area of the heat transfer could be used. Santrauka Siekiant efektyviai išnaudoti perteklinę, atliekinę ar atsinaujinančių energijos išteklių gaminamą energiją, vis dažniau taikomas fazinio virsmo medžiagų (FVM) panaudojimas pastato energetinėse sistemose. Kartu tai kelia naujus technologinius iššūkius pasirenkant konkrečias medžiagas, sistemų projektinius sprendinius, nes reikia gerai išmanyti šilumos mainų procesą vykstant fazės virsmui. Šiame darbe siekiama ištirti šilumos mainus šilumos kaupiklyje su fazinio virsmo medžiagomis naudojantis COMSOL Multiphysics programa. Analizės metu įvertintos medžiagos savybės vykstant fazės virsmui. Tai leido nustatyti, kad medžiagos šilumos laidumo koeficientas turi didelę reikšmę šilumos mainų intensyvinimui. Be to, atskirų taškų analizė tyrimo objekte atskleidė, kad per nagrinėjamąjį laikotarpį FVM paviršiniame sluoksnyje fazės virsmas neįvyksta. Siekiant to išvengti, galimi papildomi sprendimai, tokie kaip šilumai laidžių medžiagų integravimas į FVM arba šilumos mainų paviršiaus ploto didinimas.

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