2016 Fiscal Year Annual Research Report
An innovative latent thermal energy storage system encapsulated by ceramic PCM capsules for concentrated solar thermal energy plants
| Project/Area Number |
16H06810
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| Research Institution | Niigata University |
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Principal Investigator |
Bellan Selvan 新潟大学, 研究推進機構, 助教 (50785293)
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| Project Period (FY) |
2016-08-26 – 2018-03-31
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| Keywords | thermal energy storage / phase change material / latent heat storage / solar energy / Concentrated solar power |
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| Outline of Annual Research Achievements |
An experimental set up, consists of electrical heating furnace, PCM capsule and data acquisition system, has been built to study the phase-change process of the PCM encapsulated capsule. Since a large amount of heat transfer surface area can be obtained in a small volume, a packed bed thermal storage system filled with spherical PCM capsules has been considered as one of the effective methods. Hence, a spherical capsule has been made for packed bed system. PCM material was condensed in a spherical shape ceramic container. The PCM capsule was placed at the center of the heating furnace, and the temperature of the furnace was set more than 20 °C of the melting point of the PCM. The temperature at the center of the capsule was monitored using the thermocouples and data acquisition system. Thus, the complete melting behavior of the PCM capsule was investigated experimentally. A numerical model has been developed to simulate the melting process of the spherical capsule.
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| Current Status of Research Progress |
Current Status of Research Progress
2: Research has progressed on the whole more than it was originally planned.
Reason
An axisymmetric model has been developed by assuming the solid and liquid phases of the PCM are homogeneous and isotropic; the flow is laminar and incompressible. The developed model capable to obtain the characteristics of heat transfer, flow, melting-front and natural convection effect of the capsule. The finite volume method has been used to solve continuity, momentum and energy equations. Experimentally captured snapshots and numerically predicted melting phase front of the capsule during melting process have been compared for model validation. A good agreement has been found between the numerical and experimental results. The influence of capsule size and Stefan number on the melting dynamics has been studied. The main intention of this investigation is to derive a dimensionless correlation of effective thermal conductivity, which is required to develop a packed bed model of TES system. All in all, the project has been going on as per planned schedule.
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| Strategy for Future Research Activity |
Using the outcomes of single capsule thermal performance, transient two-dimensional continuous solid phase packed bed model will be developed, for a pilot scale (200 kWh) LHTES system, and validated by comparing to the reported experimental results. The dynamic thermal performance of these systems will be analyzed numerically. Using these models, detailed characteristics of the heat transfer between the capsules and heat transfer fluid will be analyzed. Parametric analyses will be conducted to study the influence of mass flow rate, Stefan number, thickness and the thermal conductivity of the shell on the thermal performance and efficiency of the tank.
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