Energy storage in a complex heat storage unit using commercial grade phase change materials: Effect of convective heat transfer boundary conditions

2018 ◽  
Vol 131 ◽  
pp. 621-641 ◽  
Author(s):  
Latifa Begum ◽  
Mainul Hasan ◽  
Georgios H. Vatistas
Keyword(s):  
Heat Transfer ◽  
Energy Storage ◽  
Boundary Conditions ◽  
Phase Change ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Phase Change Materials ◽  
Heat Storage ◽  
Storage Unit ◽  
Commercial Grade

Latent Heat Storage: Container Geometry, Enhancement Techniques, and Applications—A Review

2019 ◽  
Vol 141 (5) ◽  
Author(s):  
S. Arunachalam
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Energy Storage ◽  
Phase Change ◽  
Latent Heat ◽  
Thermal Energy ◽  
Heat Exchangers ◽  
Phase Change Materials ◽  
Heat Storage ◽  
Low Thermal Conductivity

Energy storage helps in waste management, environmental protection, saving of fossil fuels, cost effectiveness, and sustainable growth. Phase change material (PCM) is a substance which undergoes simultaneous melting and solidification at certain temperature and pressure and can thereby absorb and release thermal energy. Phase change materials are also called thermal batteries which have the ability to store large amount of heat at fixed temperature. Effective integration of the latent heat thermal energy storage system with solar thermal collectors depends on heat storage materials and heat exchangers. The practical limitation of the latent heat thermal energy system for successful implementation in various applications is mainly from its low thermal conductivity. Low thermal conductivity leads to low heat transfer coefficient, and thereby, the phase change process is prolonged which signifies the requirement of heat transfer enhancement techniques. Typically, for salt hydrates and organic PCMs, the thermal conductivity range varies between 0.4–0.7 W/m K and 0.15–0.3 W/m K which increases the thermal resistance within phase change materials during operation, seriously affecting efficiency and thermal response. This paper reviews the different geometry of commercial heat exchangers that can be used to address the problem of low thermal conductivity, like use of fins, additives with high thermal conductivity materials like metal strips, microencapsulated PCM, composite PCM, porous metals, porous metal foam matrix, carbon nanofibers and nanotubes, etc. Finally, different solar thermal applications and potential PCMs for low-temperature thermal energy storage were also discussed.

The Investigation of Phase Change Emulsion (PCE): Fabrication, Thermal Conductivity and Utilization of Nanoparticles

2013 ◽  
Vol 860-863 ◽  
pp. 862-866 ◽  
Author(s):  
Yi Fei Zheng ◽  
Zhong Zhu Qiu ◽  
Jie Chen
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Energy Storage ◽  
Phase Change ◽  
Phase Change Material ◽  
Phase Change Materials ◽  
Heat Storage ◽  
Change Material

Phase change materials in the form of emulsion (PCE) is a category of novel phase change fluid used as heat storage and transfer media. It plays an important role in commercially viable applications (energy storage, particularly).The emulsion is made of microparticles of a phase change wax (a kind of paraffin or mixture ) as a phase change material (PCM), mixed paraffin directly with water. This paper presents information on the different PCM emulsions by different researchers. It gives the method of preparation of the PCE, and makes a special effort to investigate the heat transfer phenomena and the method of enhancing the thermal conductivity of the emulsion.

scholarly journals HEAT STORAGE SYSTEM WITH PHASE CHANGE MATERIALS IN COGENERATION UNITS: STUDY OF PRELIMINARY MODEL

2008 ◽  
Vol 39 (4) ◽  
pp. 9
Author(s):  
Claudio Caprara ◽  
Giovanni Stoppiello
Keyword(s):  
Heat Transfer ◽  
Energy Storage ◽  
Phase Change ◽  
Thermal Energy ◽  
Phase Change Materials ◽  
Heat Storage ◽  
High Energy ◽  
Operating Conditions ◽  
Thermal Source ◽  
Continuous Increase

The continuous increase in the mechanization of farm activities, the rise in fuel prices and the environmental aspects concerning gas emissions are the main driving forces behind efforts toward more effective use of renewable energy sources and cogeneration systems even in agricultural and cattle farms. Nevertheless these systems are still not very suitable for this purpose because of their little flexibility in following the changing energy demand as opposed to the extremely various farm load curves, both in daytime and during the year. In heat recovery systems, the available thermal energy supply is always linked to power production, thus it does not usually coincide in time with the heat demand. Hence some form of thermal energy storage (TES) is necessary in order to reach the most effective utilization of the energy source. This study deals with the modelling of a packed bed latent heat TES unit, integrating a cogeneration system made up of a reciprocating engine. The TES unit contains phase change materials (PCMs) filled in spherical capsules, which are packed in an insulated cylindrical storage tank. Water is used as heat transfer fluid (HTF) to transfer heat from the tank to the final uses, and exhausts from the engine are used as thermal source. PCMs are considered especially for their large heat storage capacity and their isothermal behaviour during the phase change processes. Despite their high energy storage density, most of them have an unacceptably low thermal conductivity, hence PCMs encapsulation technique is adopted in order to improve heat transfer. The special modular configuration of heat exchange tubes and the possibility of changing water flow through them allow to obtain the right amount of thermal energy from the tank, according to the hourly demand of the day. The model permits to choose the electrical load of the engine, the dimensions of the tank and the spheres, thickness and diameter of heat exchanger and the nature of PCMs. According to the energy loads of the farm, a daily thermal energy balance is obtained and charging and discharging cycles during the day are showed as solid/ liquid percentages of the PCM. As an example, load curves of a milk cattle farm (100 heads of cattle), were considered in two different conditions, such as in summer and winter seasons, and model functioning was detected in both of the cases. Different PCMs were investigated for this application and TES unit dimensions were consequently changed in order to achieve optimal operating conditions. Results are presented and technical and economical issues are discussed.

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 Experimental Evaluation of Nano-Enhanced Phase Change Materials in a Finned Storage Unit

2020 ◽  
Vol 10 (3) ◽  
pp. 5814-5818
Author(s):  
M. A. Aichouni ◽  
N. F. Alshammari ◽  
N. Ben Khedher ◽  
M. Aichouni
Keyword(s):  
Energy Storage ◽  
Phase Change ◽  
Thermal Performance ◽  
Phase Change Materials ◽  
Performance Enhancement ◽  
Renewable Energy Sources ◽  
Heating System ◽  
Al2o3 Nanoparticles ◽  
Storage Unit ◽  
Experimental Apparatus

The intermittent nature of renewable energy sources such as solar and wind necessitates integration with energy-storage units to enable realistic applications. In this study, thermal performance enhancement of the finned Cylindrical Thermal Energy Storage (C-TES) with nano-enhanced Phase Change Material (PCM) integrated with the water heating system under Storage, Charging and Discharging (SCD) conditions were investigated experimentally. The effects of the addition of copper oxide (CuO) and aluminum oxide (Al2O3) nanoparticles in PCM on thermal conductivity, specific heat, and on charging and discharging performance rates were theoretically and experimentally investigated and studied in detail. The experimental apparatus utilized paraffin wax as PCM, which was filled in Finned C-TES to conduct the experiments. The experimental results showed a positive improvement compared with the non-nano additive PCM. The significance and originality of this project lies within the evaluation and identification of preferable metal-oxides with higher potential for improving thermal performance.

Solid/Liquid Phase Change Heat Transfer in Latent Heat Thermal Energy Storage

2009 ◽  
Author(s):  
D. Zhou ◽  
C. Y. Zhao
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Energy Storage ◽  
Phase Change ◽  
Calcium Chloride ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Phase Change Materials ◽  
Metal Foams ◽  
Chloride Hexahydrate

Phase change materials (PCMs) have been widely used for thermal energy storage systems due to their capability of storing and releasing large amounts of energy with a small volume and a moderate temperature variation. Most PCMs suffer the common problem of low thermal conductivity, being around 0.2 and 0.5 for paraffin and inorganic salts, respectively, which prolongs the charging and discharging period. In an attempt to improve the thermal conductivity of phase change materials, the graphite or metallic matrix is often embedded within PCMs to enhance the heat transfer. This paper presents an experimental study on heat transfer characteristics of PCMs embedded with open-celled metal foams. In this study both paraffin wax and calcium chloride hexahydrate are employed as the heat storage media. The transient heat transfer behavior is measured. Compared to the results of pure PCMs samples, the investigation shows that the additions of metal foams can double the overall heat transfer rate during the melting process. The results of calcium chloride hexahydrate are also compared with those of paraffin wax.

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