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An Experimental Investigation of Liquid Droplet Impingement on a Molten Phase Change Material as a Direct-Contact Solidification Method

Faghiri, Shahin | 2020

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 53378 (08)
  4. University: Sharif University of Technology
  5. Department: Mechanical Engineering
  6. Advisor(s): Shafii, Mohammad Behshad
  7. Abstract:
  8. Improving the discharge process of phase-change materials (PCMs) is of great importance. In this study, the process of acetone drop impact on molten paraffin, as a direct-contact solidification method, is experimentally investigated. Four Weber numbers (corresponding to heights of 10, 20, 30, and 40 cm) for the acetone drop and six surface temperatures (66, 68, 70, 75, 80, and 90 °C) for the molten paraffin are considered. As the acetone drop impacts the molten paraffin, the drop absorbs heat from the melting paraffin and boils, solidifying a portion of the molten paraffin. Two important parameters that govern the acetone drop dynamics and the solidification of the molten paraffin are the drop impact Weber number (We) and the paraffin’s surface temperature. As We increases and the paraffin surface temperature decreases, the solid paraffin area formed on the surface grows, leading to 301.64 mm2 solid surface formation at We=860.03 and a surface temperature of 66 °C. On the other hand, for temperatures higher than 80 °C, the slope of the formed solid surface versus temperature at a constant We decreases significantly. For instance, at We=860.03, the slope of the formed solid surface versus temperature in the temperature range of 75 °C to 80 °C is 54 times higher than that of the range of 80 °C to 90 °C. In all We numbers, the liquid paraffin column was formed at T=90 °C, and the jet breakup occurred at this temperature. In the end, the effect of We and the paraffin temperature on the maximum crater depth and width are discussed. It is found that as We increases, both the maximum crater depth and width increases
  9. Keywords:
  10. Phase Change Material (PCMs) ; Temperature ; Weber Number ; Solidification ; Paraffins ; Droplet Impact ; Droplet Dynamics ; Boiling ; Acetone

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