Introduction

Synthetic jet cooling meets demands for air cooled heat exchangers to bear elevated thermal management loads created by increasingly powerful heat sources. Synthetic jet heat sinks cooling excels in meeting consumer electronics design needs.

The rise in power dissipation levels of microprocessors accompanied by a shrinking thermal budget has resulted in the need for advanced active heat sinks cooling solutions. The International Technology Roadmap for Semiconductors [1] predicts a junction-ambient thermal resistance requirement of 0.33° C/W for cost performance computers by 2010. The steep cooling requirements have prompted development of two phases and pumped liquid cooling techniques and it is perceived that even consumer systems will eventually need to use fluids other than air for cooling. However, in a recent review of the advances in electronics cooling, Bar-Cohen [2] noted that while two-phase and liquid cooling have potential for very high heat-removal requirements, consumer oriented systems have focused on air cooling due to its simplicity.

It appears that until liquid or two-phase cooling concepts reach a stage at which they can be reliably packaged, active air cooled heat exchangers will continue to be the primary choice for thermal designers. In order to achieve the ever increasing power dissipation levels with current fan-heat-sink combinations, designers are being forced to use copper heat sinks or aluminum heat sinks with copper inlays as well as larger fans driving higher flow rates. While fans are capable of supplying ample volume flow rate, they are hindered by noise, long-term reliability, and low thermal effectiveness. Arrays of air-jets impinging on the heated surfaces can be used as an alternative to fans, but conventional air-jets are not very useful for consumer products.

While there is extensive literature on direct air cooling using fans and conventional jets, the concept of using synthetic jets for heat sinks cooling is relatively new.

The present work focuses on the development of active air-cooled heat exchangers based on the syn-jet ejector principle. Section 2 describes the experimental setup including the design of the heat sink. Section 3 discusses thermal performance of the heat sink. Section 4 presents the conclusions from this work.

Abstract

Thermal Performance of Synthetic-Jet-Based Heat Sinks Cooling

The design and thermal performance of synthetic-air-jet-based heat sinks cooling for high-power dissipation electronics is discussed. Each fin of a plate-fin heat sink is straddled by a pair of two-dimensional synthetic jets, thereby creating a jet ejector system that entrains cool ambient air upstream of the heat sink and discharges it into the channels between the fins. The jets are created by periodic pressure variations induced in a plenum by electromagnetic actuators. The performance of the heat sink is assessed using a thermal test die encased in a heat spreader that is instrumented with a thermocouple.

Applications

LED Cooling, Chip Cooling, Fan Augmentation: Recommended Syn Jet Applications

The high thermal efficiency of a synthetic jet cooling solution outpaces other options for a wide range of designs requiring flexible form factor, high reliability, or low power cooling. SynJet air cooled heat exchangers are highly recommended for LED cooling, chip cooling, and many fan augmentation scenarios.

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