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Experimental Investigation of Lithium Nitrate Trihydrate and Calcium Chloride Hexahydrate as Salt Hydrate PCMs for Thermal Energy Storage

Kannan, Sarath
http://orcid.org/0000-0001-9731-6033
http://rave.ohiolink.edu/etdc/view?acc_num=ucin1563273912013393

Abstract Details

2019, MS, University of Cincinnati, Engineering and Applied Science: Mechanical Engineering.
One of the major steps taken against global warming is to reduce the dependency of fossil fuels that forms 78.9% of the primary energy consumed [1]. This effort is pushed forward primarily by designing more efficient systems and tapping in to renewable sources of power. Thermal energy storage (TES) systems provide numerous solutions for such challenges. Some of them include providing optimum temperature for system operation from chips in computers to condensers in thermal power-plants. TES also help to capture and store intermitted supply of solar energy for later use such as in concentrated solar power plants and district heating applications. It also has applications in HVAC, aviation and process industries [2]. With the increase in demand for such solutions the market for TES systems and Phase Change Materials is expect to double by 2023. This research explores salt hydrate based phase-change materials (PCM) that can store this heat. These salts are screened and promising ones are characterized based on their thermal properties and cycling stability. After screening several salt hydrate based PCM in the melting range of 25-35°C, Lithium Nitrate Trihydrate and Calcium Chloride Hexahydrate was chosen because of their relatively stable behavior. Firstly, the phase change temperature and the latent heat capacity was measured using the Lumped Capacitance T-History method. Following which a mDSC was used to measure the specific heat. Additionally, the density of the liquid and solid phase was also determined using Archimedes’ Principle. After the initial characterization, the effects of nucleating agents on Lithium Nitrate Trihydrate (LNT) and Calcium Chloride Hexahydrate (CCH) was studied. CCH was doped with a known nucleating agent - SrCl2- which reduced subcooling to <4°C and thermal capacity to 167kJ/kg from 187kJ/kg. In the case of LNT a novel nucleating agent was discovered by conducting crystallographic using lattice mismatch technique. The new nucleating agent – Zinc Nitrate Hexahydrate (ZNH, ZnNO3.6H2O) – suppresses sub cooling to ?Ts<5°C. This however resulted in reduction of the latent heat storage capacity to 130kJ/kg from 244kJ/kg after the end of 1000 cycles. The thermal stability study of the PCM was conducted by subjecting the PCM samples to repeated thermal cycles in water bath using two methods. First by the cold finger method, where the PCM is partially melted leaving behind few solid crystals that serve as nucleation sites during solidification. Secondly by complete melting and solidification of the PCM with the help of nucleating agents. It was found that cold finger resulted in negligible loss in thermal capacity at the end of 100 cycles whereas addition of nucleating agents degraded the thermal capacity at the end of thermal cycling. The mechanism that leads to this degradation is also discussed.
Raj Manglik, Ph.D. (Committee Chair)
Milind Jog, Ph.D. (Committee Member)
Navin Kumar, Ph.D. (Committee Member)
74 p.
Energy
Salt Hydrate; Thermal Energy Storage; PCM; Lithium Nitrate Trihydrate; Calcium Chloride Hexahydrate; Nucleation

Recommended Citations

Citations

  • Kannan, S. (2019). Experimental Investigation of Lithium Nitrate Trihydrate and Calcium Chloride Hexahydrate as Salt Hydrate PCMs for Thermal Energy Storage [Master's thesis, University of Cincinnati]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1563273912013393

    APA Style (7th edition)

  • Kannan, Sarath. Experimental Investigation of Lithium Nitrate Trihydrate and Calcium Chloride Hexahydrate as Salt Hydrate PCMs for Thermal Energy Storage. 2019. University of Cincinnati, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ucin1563273912013393.

    MLA Style (8th edition)

  • Kannan, Sarath. "Experimental Investigation of Lithium Nitrate Trihydrate and Calcium Chloride Hexahydrate as Salt Hydrate PCMs for Thermal Energy Storage." Master's thesis, University of Cincinnati, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1563273912013393

    Chicago Manual of Style (17th edition)

ucin1563273912013393
440
© 2019, some rights reserved.Creative Commons License Experimental Investigation of Lithium Nitrate Trihydrate and Calcium Chloride Hexahydrate as Salt Hydrate PCMs for Thermal Energy Storage by Sarath Kannan is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License. Based on a work at etd.ohiolink.edu.
This open access ETD is published by University of Cincinnati and OhioLINK.