Skip to Main Content
 

Global Search Box

 
 
 
 

Files

File List


17345.pdf (5.42 MB)

ETD Abstract Container

Abstract Header

Enhanced Heat Transfer in Micro-Scale Heat Exchangers Using Nano-Particle Laden Electro-osmotic Flow (EOF)

Al-Rjoub, Marwan Faisal
http://rave.ohiolink.edu/etdc/view?acc_num=ucin1439305691

Abstract Details

2015, PhD, University of Cincinnati, Engineering and Applied Science: Mechanical Engineering.
This dissertation presents the fabrication and testing of a new design of an electro-osmotic flow (EOF) driven micro-pump. Considering thermal management applications, three different types of micro-pumps were tested using multiple liquids. The micro-pumps were fabricated from a combination of materials, which included: silicon-polydimethylsiloxane (Si-PDMS), Glass-PDMS, or PDMS-PDMS. The flow rates of the micro-pumps were experimentally and numerically assessed. Different combinations of materials and liquids resulted in variable values of zeta-potential. The ranges of zeta-potential for Si-PDMS, Glass-PDMS, and PDMS-PDMS were –42.5 to –50.7 mV, –76.0 to –88.2 mV, and –76.0 to –103.0 mV, respectively. The flow rates of the micro-pumps were proportional to their zeta-potential values. In particular, flow rate values were found to be linearly proportional to the applied voltages below 500 V. A maximum flow rate of 75.9 µL/min was achieved for the Glass-PDMS micro-pump at 1 kV. At higher voltages non-linearity and reduction in flow rate occurred due to Joule heating and the axial electro-osmotic current leakage through the silicon substrate. The fabricated micro-pumps could deliver flow rates, which were orders of magnitude higher compared to the previously reported values for similar size micro-pumps. It is expected that such an increase in flow rate, particularly in the case of the Si-PDMS micro-pump, would lead to enhanced heat transfer for micro-chip cooling applications as well as for applications involving micro-total analysis systems. The Si-PDMS micro-pump was modified to be used as a micro-scale heat exchanger for the thermal management of hot spots generated by microchips. Various cooling liquids including, deionized water, distilled water, borax buffer, and Al2O3 nano-particle solution, were tested and compared based on their flow rates and the increase in the temperature of the cooling liquid. A constant heat flux heater was used to simulate the heat generated by micro-chip devices. The flow rate of the cooling liquid and its temperatures at the inlet and the outlet reservoirs were measured. Deionized water produced a flow rate of 30.1 µL/min and 2 ºC increase between the inlet and the outlet reservoirs temperatures at 1 W heating power and 400 V of EOF. The flow rate and the increase in temperature of distilled water at the same conditions were 22.7 µL/min and 3 ºC, respectively. For the borax buffer the flow rate was 33.1 µL/min and the increase in temperature was 2.7 ºC. Most notably, there was an increase in temperature of 2.4 ºC with a lower flow rate of 20.4 µL/min when the Al2O3 nano-particle solution was used. Among all cooling liquids, the Al2O3 nano-particle solution showed the highest scaled specific heat energy removal with a maximum of ~ 69% increase compared to deionized water. Further, the current micro-scale heat exchanger device was able to produce higher electro-osmotic flow rates due to the use of PDMS on three sides of the micro-channel; thus providing smoother walls and higher zeta-potential while the silicon surface allowed heat transfer to the cooling liquid. The increased flow rate allowed enhanced heat removal from higher heat flux areas (hot spots) of microelectronic devices without the need for high-pressure pumping systems.
Rupak Banerjee, Ph.D P.E. (Committee Chair)
Sabyasachi Ganguli, Ph.D. (Committee Member)
Ajit Roy, Ph.D. (Committee Member)
Michael Kazmierczak, Ph.D. (Committee Member)
Teik Lim, Ph.D. (Committee Member)
150 p.
Mechanics
Electro-osmotic flow; Micro-scale heat exchanger; Thermal management; Micro-pump

Recommended Citations

Citations

  • Al-Rjoub, M. F. (2015). Enhanced Heat Transfer in Micro-Scale Heat Exchangers Using Nano-Particle Laden Electro-osmotic Flow (EOF) [Doctoral dissertation, University of Cincinnati]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1439305691

    APA Style (7th edition)

  • Al-Rjoub, Marwan. Enhanced Heat Transfer in Micro-Scale Heat Exchangers Using Nano-Particle Laden Electro-osmotic Flow (EOF). 2015. University of Cincinnati, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ucin1439305691.

    MLA Style (8th edition)

  • Al-Rjoub, Marwan. "Enhanced Heat Transfer in Micro-Scale Heat Exchangers Using Nano-Particle Laden Electro-osmotic Flow (EOF)." Doctoral dissertation, University of Cincinnati, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1439305691

    Chicago Manual of Style (17th edition)

ucin1439305691
307
© 2015, some rights reserved.Creative Commons License Enhanced Heat Transfer in Micro-Scale Heat Exchangers Using Nano-Particle Laden Electro-osmotic Flow (EOF) by Marwan Faisal Al-Rjoub is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License. Based on a work at etd.ohiolink.edu.
This open access ETD is published by University of Cincinnati and OhioLINK.