Investigation of High Frequency Synthetic Jet Heat Transfer Characteristics for Advanced Electronics and Energy Systems

English

With the recent advancement in electronics, silicone micro fabrication technology enabled nanometer sized electronics circuits enabling advanced devices such as laptops, celluler phones and defense electronics. These innovations lead to smaller electronics with much functionality resulting in high heat generatıons and heat fluxes (>100 W/cm2) while reducing the available area and volume for thermal design.

Cost, size, reliability, and availability have been major constraints for the selection of an optimized thermal solution. Air-cooling has been investigated over the last five decades including natural and forced convection applications. While various cooling technologies such as small rotary fans, piezo fans, ionic winds are proposed, synthetic jets provided superior thermal performance given in the published literature. Synthetic jets, small-scale devices operating with zero-net-mass-flux principle by sucking and blowing of high velocity working fluid from a single opening (orifice), that will aim towards a hot electronics component and provide efficient cooling capability. The device produces periodic jet streams, which may have peak velocities in excess of 20 times of conventional, comparable size fan velocities.

In this research, an experimental and computational study for advanced synthetic jets has been performed. This novel jets will be designed and manufactured at Ozyegin University laboratories. The effect of heat transfer due to novel synthetic jets will be compared with the natural convection as baseline. A new experimental set-up isdesigned and manufactured. Thermal experiments are performed over a vertical heater (20 mm). The primary effects in the experimental study are operating voltage and frequency, orifice geometry, jet-to-heater spacıng, heater geometry, and heat flux. A close form heat transfer correlation will be proposed. Thermodynamics efficiency of a cooling system is very important so that for a wide range of operating conditions thermodynamic efficiency, coefficient of performance, (COP) will be determined. High frequency pulsating flow consumes ver low power, but it creates tremendous vortex-shedding opportunity causing effective cooling at a very low power consumption leading to high COPs.

While cooling performance is very critical for practical application, low power consumption is also very critical. Therefore, in this project we aim for developing a new technology by means of scientific research (models) for design of jets, manufacture synthetic jets, test with scientific methods, and finally develop a heat transfer correlation. In this project, we will develop high frequency and high performance synthetic jets cooling, and test for our national electronics systems (military and consumer) for possible implementation in the future. Possible implementation of these new high frequency synthetic jets for energy technologies such as solar photovoltaic (PV) systems will also be possible beyond electronics systems.

 

 

Şekil 1: Bir ART sentetik jetinin mekanik davranışı

 

Şekil 2: Bir ART sentetik jetinin modelleri ve deneysel validasyonu

 

 

Şekil 3: Akış esansında vorticity yapısı, Rej = 211.

 

Şekil 4: Bir ART sentetik jeti için hız dağılımı (f=450 Hz ve H/Dh=5).