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Experimental Investigation into the Effect of Nanoparticles on the Solidification Rate of Phase Change Material in Intermediate Boiling Fluid Method

Hosseini Naveh, Hossein | 2020

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 53090 (08)
  4. University: Sharif University of Technology
  5. Department: Mechanical Engineering
  6. Advisor(s): Shafii, Mohammad Behshad
  7. Abstract:
  8. The low melting and solidification rates of phase change materials, which traces back to their low thermal conductivity coefficient, has led the application of these materials to face limitations. In this study, it is attempted to enhance the energy storage process in phase change materials for a complete charge-discharge cycle using a novel method called SFD-IBF. Throughout this novel technique paraffin and acetone are used as phase change material and intermediate boiling fluid, respectively. In the solidification process, there is no direct contact between the cold source and the molten paraffin, while acetone, as an intermediate fluid, is being boiled via adsorbing paraffin’s heat and ultimately causing paraffin to be cooled down. Afterward, acetone vapor loses its heat to the condenser, condenses and falls into the paraffin again. This cycle takes place until the full solidification of paraffin is met. As for the melting process, in addition to convection heat transfer of molten paraffin, the movement of vapor acetone as well as penetration and releasing its latent heat into upper layers of paraffin lead to an increase in heat transfer. Using this method under the optimum condition, the solidification time, melting time, and the total melting and solidification time are enhanced almost 77 times, 22 percent, and 80 percent, respectively, compared to the conventional method. Simultaneous use of nanoparticles and acetone due to increasing the thermal conductivity of paraffin can increase the rate of conductive heat transfer and thus significantly reduce the melting and freezing time.. The reduction in freezing time is 121 times for CNT and acetone for simultaneous use and 97 times for simultaneous use of 〖Fe〗_3 O_4 and acetone. Melting time is also reduced by 25.3% in the simultaneous use of CNT and acetone and by 24% in the simultaneous use of 〖Fe〗_3 O_4 and acetone. Also, the differential scanning calorimetry test results indicated that the utilization of acetone has minimal effects on the thermal properties of paraffin
  9. Keywords:
  10. Phase Change Material (PCMs) ; Discharge ; Melting ; Solidification ; Super Fast Discharge ; Intermediate Boiling Fluid

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