Improvement of the thermal performance of a solar triple concentric-tube thermal energy storage unit using cascaded phase change materials

2021 ◽  
Vol 42 ◽  
pp. 103047
Author(s):  
Radouane Elbahjaoui
Keyword(s):  
Energy Storage ◽  
Phase Change ◽  
Thermal Performance ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Phase Change Materials ◽  
Storage Unit ◽  
Energy Storage Unit

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.

scholarly journals Phase-Transition Thermal Charging of a Channel-Shape Thermal Energy Storage Unit: Taguchi Optimization Approach and Copper Foam Inserts

Molecules ◽  
2021 ◽  
Vol 26 (5) ◽  
pp. 1235
Author(s):  
Mohammad Ghalambaz ◽  
Seyed Abdollah Mansouri Mehryan ◽  
Ahmad Hajjar ◽  
Obai Younis ◽  
Mikhail A. Sheremet ◽  
...  
Keyword(s):  
Energy Storage ◽  
Phase Change ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Metal Foam ◽  
Volume Fraction ◽  
Foam Layer ◽  
Storage Unit ◽  
Energy Storage Unit ◽  
Copper Foam

Thermal energy storage is a technique that has the potential to contribute to future energy grids to reduce fluctuations in supply from renewable energy sources. The principle of energy storage is to drive an endothermic phase change when excess energy is available and to allow the phase change to reverse and release heat when energy demand exceeds supply. Unwanted charge leakage and low heat transfer rates can limit the effectiveness of the units, but both of these problems can be mitigated by incorporating a metal foam into the design of the storage unit. This study demonstrates the benefits of adding copper foam into a thermal energy storage unit based on capric acid enhanced by copper nanoparticles. The volume fraction of nanoparticles and the location and porosity of the foam were optimized using the Taguchi approach to minimize the charge leakage expected from simulations. Placing the foam layer at the bottom of the unit with the maximum possible height and minimum porosity led to the lowest charge time. The optimum concentration of nanoparticles was found to be 4 vol.%, while the maximu possible concentration was 6 vol.%. The use of an optimized design of the enclosure and the optimum fraction of nanoparticles led to a predicted charging time for the unit that was approximately 58% shorter than that of the worst design. A sensitivity analysis shows that the height of the foam layer and its porosity are the dominant variables, and the location of the porous layer and volume fraction of nanoparticles are of secondary importance. Therefore, a well-designed location and size of a metal foam layer could be used to improve the charging speed of thermal energy storage units significantly. In such designs, the porosity and the placement-location of the foam should be considered more strongly than other factors.

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