Thermal Management of Low Profile Electronic Equipment Using Radial Fans and Heat Sinks

Abstract

There is an increasing need for low profile thermal management solutions for applications in the range of 5–10W, targeted at portable electronic devices. This need is emerging due to enhanced power dissipation levels in portable electronics, such as mobile phones, portable gaming machines, and ultraportable personal computers. This work focuses on the optimization of such a solution within the constraints of the profile and footprint area. A number of fan geometries have been investigated where both the inlet and exit rotor angles are varied relative to the heat conducting fins on a heat sink. The ratio of the fan diameter to the heat sink fin length was also varied. The objective was to determine the optimal solution from a thermal management perspective within the defined constraints. The results show a good thermal performance and highlight the need to develop the heat sink and fan as an integrated thermal solution rather than in isolation as is the traditional methodology. An interesting finding is that the heat transfer scales are in line with turbulent rather than laminar correlations despite the low Reynolds number. It is also found that while increasing the pumping power generally improves the thermal performance, only small gains are achieved for relatively large pumping power increases. This is important in optimizing portable systems where reduced power consumption is a competitive advantage in the marketplace.

Heat transfer model for gas–liquid slug flows under constant flux

“…In heat transfer applications, this has been primarily driven by advances in microprocessor performance, as the computing industry is currently curtailed by increased heat flux levels due to reduced die size and increased numbers of transistors. This problem of elevated heat flux has led numerous researchers to investigate many novel air cooled heat sink designs [1][2][3][4] and to examine the efficiency of blade geometry in the miniature fans required [5,6]. Also, the advent of microchannel technology has lead to the development of numerous liquid cooling devices, such as cold plates for processor cooling, and compact heat exchangers for industrial applications.…”

Local heat transfer performance and exit flow characteristics of a miniature axial fan

“…Hence, there is a need to examine the performance of smaller scale fans which could possibly be implemented to enhance heat transfer in portable devices. The combined performance of miniature centrifugal fans with inline heat sinks have been investigated for low profile applications (Walsh and Grimes, 2007;Walsh et al, 2008;Egan et al, 2009a,b;Stafford et al, 2009a). All of these studies examine global heat transfer performance through averaged heat transfer coefficient or thermal resistance values.…”

An Experimental Investigation of Heat Transfer Enhancement Mechanisms in Microencapsulated Phase-Change Material Slurry Flows

“…The result is that conventional air-based cooling solutions are no longer adequate in many applications, leading to numerous authors investigating the use of alternative cooling technologies. These range from novel microfan and heat-sink designs [8][9][10][11][12][13][14] to the use of nanofluids [15] in liquid cooling solutions. Hence, if the aforementioned attributes of MPCM slurries can be realized, they have significant potential in this, along with many other sectors requiring highly efficient heat exchange devices.…”