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Numerical Investigation of Ambient Pressure and Electric Potential on the Heat Transfer Rate of an Electrospray

Neyzan Hosseini, Amir Mohammad | 2023

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 56541 (45)
  4. University: Sharif University of Technology
  5. Department: Aerospace Engineering
  6. Advisor(s): Ghorbanian, Kaveh
  7. Abstract:
  8. Electrospray is a process in which the charged liquid is subjected to the effect of an electric field and after passing through an emitter, it will propagate in the form of jets or small droplets. This process is used in applications such as electric thrusters, cooling or mass spectrometry. In the electronics industry, cooling high-temperature microprocessors is a challenge. In this regard, air-based cooling systems are not well able to discharge heat from electrical and electronic components. Electrospray cooling technology is one of the new and promising methods. In this research, the two-dimensional simulation of electrospray cooling is performed by using COMSOL commercial software as a numerical solver. In this regard, the effect of ambient pressure and applied electric potential on the heat transfer rate is studied. In the present study, ethanol is used as the working fluid with a constant flow rate, and the changes in the temperature of the hot surface and the displacement heat transfer coefficient in the ambient pressure ranging from 100 to 200 kPa and the electric potential of 4 to 6.5 kV are investigated. The results indicate that the heat transfer efficiency has an inverse relationship with the ambient pressure. Also, based on the simulation results, with the increase in ambient pressure, the displacement heat transfer coefficient is decreased. This is due to the increase in the shear stress force between the two phases at higher pressures which has led to a decrease in the speed of the droplets hitting the surface. According to the results and contrary to the effect of increasing ambient pressure, a direct relationship between applied electric potential and displacement heat transfer coefficient is observed. As the electric potential increases, the heat transfer coefficient also increases. The reason for this is the strengthening of the electrostatic force entering the interface of two phases (ethanol and air) due to the increase of the electric field. As a result, the formed droplets hit the hot surface at a higher speed
  9. Keywords:
  10. Electrospray ; Two Phase Flow ; Heat Transfer ; Spray Cooling ; Heat Transfer Coefficient

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