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Experimental Investigation of the Effect of Nano-Fluid on the Performance of Pulsating Heat Pipe

Mohammadi, Maziar | 2012

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 43548 (08)
  4. University: Sharif University of Technology
  5. Department: Mechanical Engineering
  6. Advisor(s): Saeedi, Mohammad Hassan; Kazemzadeh Hannani, Siamak; Shafii, Behshad
  7. Abstract:
  8. Improving efficiency of heat exchangers has always been an important concern for the industry. Pulsating Heat Pipes (PHPs) are novel and efficient technology in the field of heat transfer. PHPs are widely used in solar water heaters, solar desalination systems, etc. In this research, thermal performance of Open Loop Pulsating Heat Pipes (OLPHPs) using three different ferrofluids (ferrofluid without surfactant and nanoparticles’ coating, ferrofluid with coating of nanoparticles, and ferrofluid with surfactant) is experimentally investigated. In addition, effects of charging ratio (20, 40, 60, and 80%), heating power (20, 30, 40, 50, 60, 70, 80, 100, 120, 140, 160, 180, 200, 240, 280, 320, 360, 400, 440, 480 W), Non-Condensable Gases (NCGs), and application of magnetic field on start-up and steady thermal performance of PHPs is explored. Results show that all of the investigated ferrofluids can improve heat transfer of PHPs in comparison to distilled water as the working fluid, under certain conditions. Moreover, application of magnetic field on ferrofluid charged OLPHP results in reduction of evaporator temperature and thermal resistance. Coating of nanoparticles results in an improvement in start-up and a decline in steady state performance of PHPs. In the absence of magnetic field, thermal performance of ferrofluid with surfactant is better than ferrofluid without surfactant. In the case of water charged PHPs, 40 and 60 % charging ratios lead to better start-up and steady state thermal performances. In the case of ferrofluid without nanoparticles’ coating and surfactant, and lower heating powers, 20% charging ratio leads to a better thermal performance. While, at higher heating powers 60% is the optimum charging ratio. For ferrofluids with nanoparticles’ coating or surfactant, unless dry out is not occurred, lower charging ratios have a better thermal performance. In the case of steady state performance, higher NCGs lead to a reduction in heat transfer. One of the most important novelties of this research is an OLPHP that its start-up or steady thermal performance can be adjusted using magnetic field.

  9. Keywords:
  10. Pulsating Heat Pipe ; Heat Resistance ; Filling Ratio ; Ferrofluid ; Startup Performance ; Steady State Performance ; Noncondensable Gases ; Heating Power

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