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Experimental Investigation of Paraffin Nano-encapsulated Phase Change Material on Heat Transfer Enhancement of Pulsating Heat Pipe

Heydarian, Gholamreza | 2018

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 51079 (08)
  4. University: Sharif University of Technology
  5. Department: Mechanical Engineering
  6. Advisor(s): Shafii, Mohammad Behshad; Rezaee Shirin-Abadi, Abbas; Ghasempour, Roghayeh
  7. Abstract:
  8. In this study, a mixture of nano-encapsulated phase change materials in water has been used as a working fluid in a pulsating heat pipe in order to investigate its thermal performance. The results of the experiments showed that using the nano-encapsulated paraffin dispersed in water as working fluid improves heat transfer and decreases the thermal resistance of the pulsating heat pipe. On the other hand, there is an optimal concentration among tested concentrations for nano-encapsulated paraffin, in which increasing its concentration due to the increased dynamic viscosity of the fluid causes an increase in the thermal resistance of the pulsating heat pipe. Enhancement in the thermal performance of the pulsating heat pipe by adding paraffin nanocapsules is attributed to the increase in effective specific heat of the fluid mixture as a result of the latent heat of paraffin nanocapsules. Higher effective sensible heat leads to convective heat transfer augment which has the main role in heat transfer of heat pipes. Moreover, the existence of nano-encapsulated paraffin can results in mixing which is another reason for heat transfer enhancement. In addition, the use of nano-encapsulated phase change paraffin at high concentrations causes a cessation in the dry out phenomenon at higher heat input compared with water, or, in other words, increases the operating range of the pulsating heat pipe, which is due to increase in the heat capacity of the fluid. In addition, the effect of inclination angle (30, 60, and 90°) on the thermal performance of the PHP at an optimum concentration among tested concentrations of nano-encapsulated paraffin was investigated, which was equal to 6.25 g/lit. It was observed that the PHP had its best thermal performance at the vertical position. Moreover, at 30°, the thermal resistance of the PHP increases significantly
  9. Keywords:
  10. Pulsating Heat Pipe ; Optimal Concentration ; Heat Resistance ; Heating Power ; Nano-Encapsulated Phase Change Paraffin

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