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Simulation of the Effects of Nanofluids on the Thermal Performance of a Heat Pipe

Mirahmadi, Hamid Reza | 2017

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  1. Type of Document: M.Sc. Thesis
  2. Language: English
  3. Document No: 50054 (58)
  4. University: Sharif University of Technology, International Campus, Kish Island
  5. Department: Science and Engineering
  6. Advisor(s): Moosavi, Ali; Kazemzadeh Hannani, Siamak
  7. Abstract:
  8. In terms of thermodynamics and heat transfer, heat pipes such as closed two-phase thermosyphon are of great importance in saving energy. In this study, a computational fluid dynamics model for simulation of a thermosyphon heat pipe with two-phase flow including phase change heat transfer was developed. The study has mainly focused on the effects of volume concentrations of Nanoparticles and the operating temperature on the heat transfer performance of the thermosyphon. The analysis was performed to compare heat transfer performance between a solid copper tube and a thermosyphon heat pipe which contained deionized water and graphene oxide(GO)/water Nanofluid as its working fluids. Based on a constant heat flux of 172.87 W, as the input heat, a thermosyphon and a solid copper tube (solid domain) were simulated, and numerical results were compared with the existing experimental data to validate our simulation. Initial simulation of thermosyphon shows a good approximation with the experimental results and a 135% of enhancement in effective thermal conductivity in comparison to the copper tube solid in same boundary and geometry conditions. Then four different volumetric concentrations of graphene oxide Nanoparticles of 0.0 vol.%, 0.025 vol.%, 0.05 vol.% and 0.1 vol.% was selected. This working fluid was assumed as a single and homogeneous phase inside the thermosyphon and the calculations were conducted based on a constant temperature of 380.0 K as input heat. In the present study the total heat transfer rate, thermal resistance, thermal efficiency, effective thermal conductivity and deference temperature between evaporation and condensation sections of thermosyphon using Nanofluid have been investigated. The results show that the most enhancement in heat transfer rate was about 48% when volumetric concentration of Nanoparticles was increased to 0.1%. Also numerical results showed that the volume concentration of Nanoparticles had a significant effect in reducing the temperature difference between the evaporator and condenser which resulted in thermal resistance reduction and an increase in heat transfer rate
  9. Keywords:
  10. Thermosiphons ; Nanofluid ; Concentration ; Heat Resistance ; Heat Transfer ; Thermal Performance

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