DANIEL KEARNEY BEng
PhD Research Postgraduate (2005-2008)

e: daniel.kearney@ul.ie

t: +353-61-202471

Daniel Kearney graduated from the University College Dublin in 2005 with an honours degree in Mechanical Engineering. He has been awarded a postgraduate scholarship to study at Stokes, funded under Enterprise Ireland's Industry-Led Research Programme in Power Electronics.

PhD Project Title: Design of Meso-Scale Fans and Pumps

Background: Thermal control of electronic systems is imperative in order to ensure specified levels of performance and reliability. The choice of cooling technique depends on a range of factors: heat dissipation; heat flux; ambient temperature; maximum component temperatures; space and weight restrictions; acoustic noise limitations; maintenance requirements; and cost. For systems with moderate heat dissipation, fan-driven forced convection air cooling is the technology most commonly deployed in practice. Conventional forced air cooling offers a number of advantages: readily available cooling medium; ease of implementation and packaging; low cost; and relatively low maintenance requirements. There are a number of disadvantages, however – convective heat transfer coefficients only of order 100 W/m2°C; space requirements for airflow and heat sinks; acoustic noise generation; and the limited reliability of fans. Although there has been recent discussion about extending the limits of air cooling, it is clear that the adaptation of liquid cooling is imminent for many high power applications due to increasing heat flux levels at die, package and substrate.

The objective of the proposed research project is to design, fabricate and characterise an integrated fan and pump combination suitable for the liquid cooling of electronic systems. A range of analytical, numerical and experimental methods will be applied in order to develop a meso-scale fan / pump suitable for the pressure and flow rates required for typical primary and secondary heat exchangers. Analysis and simulation (Fluent and Flotherm) will be performed to determine the rotor speeds, rotor sizes, and blade angles to meet the pressure drop and flow requirements for a range of air and liquid flow networks. Rapid prototyping techniques will be used to create physical models of the designs to validate the numerical models. Existing flow facilities will be adapted to measure the flow characteristics of a set of fans and pumps. A motor will be selected which allows for easy integration of the fan and pump rotors, and which meets their speed and torque requirements. The key risk in the integration of the fan and pump will be designing their rotors to allow matching of their rotational speeds. If such a design criteria cannot be met then a gearing mechanism will be implemented as a contingency so that they can be operated at different speeds. The anticipated outcome of the research will be an integrated fan and pump combination for the liquid cooling of electronics, with a fundamental understanding of its operation.

Publications to date

Kearney, D., Punch, J. and Grimes, R., 2007, “An Experimental and Theoretical Investigation of the Pumping Performance of Geometrically Similar Miniature Scale Centrifugal Pumps”, submitted to the ASME-JSME Thermal Engineering and Summer Heat Transfer Conference, HT2007-321519, Vancouver, BC, Canada, July 8-12.

Kearney, D., Punch, J. and Grimes, R., 2006, “An Experimental Investigation of Flow Fields within Miniature Scale Centrifugal Pumps”, Proceedings of the American Society of Mechanical Engineers International Mechanical Engineering Congress and Exposition, IMECE2006-14283, Chicago, IL, November.