Niall O'Keeffe, BEng
PhD Research Postgraduate

e: niall.okeeffe@ul.ie

t: +353-61-202471

Niall O’Keeffe began his third level education at the Limerick Institute of Technology where he completed a BEng (ordinary) in Automation & Control Technology in 2005. To further his studies he transferred to the University of Limerick and graduated with a first class honours degree in Mechanical engineering in 2007. Niall was awarded an IRCSET postgraduate scholarship and commenced his research at Stokes in October 2007.

PhD Project Title: Drag reduction Techniques for Microchannels

In recent times there has been an increasing demand for miniaturised electronic components and so more electronic components are crammed into smaller spaces, creating devices with extremely high power densities. In 1965 Gordon Moore (co-founder of the Intel Corporation) predicted that the number of transistors on an integrated circuit would double every two years, and to the present day the growth of transistor population in Intel’s microprocessor chips has consistently matched this trend. As a result of this it has become increasingly difficult to maintain the optimum operating temperature of these complex integrated circuits using conventional air cooling technology. Liquid cooling using microchannels as heatsinks has the potential to effectively remove the excess heat generated by these high power density devices. However as the channel diameter reduces the pressure drop across these microchannels increases and therefore requires more pumping power, increasing the risk of leakage and reducing the systems efficiency and reliability.

The aim of this project is to reduce the pressure needed to drive the fluid along the microchannels using textured surfaces with superhydrophobic properties. These surfaces use arrays of nano scaled pillars which reduce the surface area in contact with the fluid and trap a gas layer along the channel walls, thus reducing the shear forces acting on the moving fluid. Unfortunately the gas layer also acts to insulate the channel wall, so there is a design trade-off that must be made for this technique to give an overall performance improvement. The outcome of this research should develop and optimise the performance of these surfaces in order to make microchannel liquid cooling a viable option for the electronics industry.

This research projected is conducted in conjunction with Bell Labs Ireland and Bell Labs NJ, USA, under the umbrella of the SFI funded Centre for Telecommunications Value-Chain Research (CTVR).

Publications to Date

Eason, C.J., O’Keeffe, N., Enright, R., Dalton, T., 2007 “On correlating experimental pressure flow and heat transfer measurements from silicon microchannels with theoretical calculations”, submitted to the ASME-JSME Thermal Engineering Summer Heat Transfer Conference, HT2007-32618, Vancouver, BC, Canada, 8-12 July 2007.