We studied a jet impingement heat sink for cooling modular power semiconductor devices. The purpose of the study was to investigate the influences on cooling performance of simplified structures of the heat sinks that suppresses the jet velocity to avoid pitting corrosion or erosion of the impingement wall. The influence on the cooling performance of partition plates used to prevent mutual interference between jets from circular nozzles was verified. We confirmed the influence on the cooling performance of the wall shape of the header and the influence of the distance from the nozzle to the wall (jet height) in the case of small ratio of the jet height to the nozzle diameter. We verified the influence on the cooling performance of the relation between the directions of the array of multiple jets and the direction of the exhaust flow. Flow visualization was performed using a mock-up model of a jet impingement heat sink. From the visualization, we found the reason on the influence of the relation between those directions. As a result, we found that the structure of the heat sink was able to be simplified maintaining the cooling performance of the conventional heat sink.

Influence on Cooling Performance of Jet Impingement Heat Sink Structures

Impinging jets have been widely used for increasing heat transfer in engineering applications such as cooling of hot steel plates and turbine blades, tempering of glass, drying of papers and films and cooling of electronic components. In the last decades, the semiconductor industry developed so rapidly that the size of electronic component has become less and less. This trend results in the increase of power density, and the simultaneous increase of heat flux on the apparatus. As most of the electronic chips operate only in some range of temperature, it is very important to accelerate the heat dissipation of electronic components. It is obviously that the traditional natural and forced convection methods can’t satisfy the cooling of such high heat flux density. In this situation, the swirling jet impingement gets more and more attention as a very potential alternative because of its much better heat transfer effect than the other methods. The objective of the study is to investigate the characteristics of the heat transfer for swirling jet impingement on a surface which aims to enhance the heat transfer rate and also to compare heat transfer characteristics of straight impinging jet and swirl flow impinging jet. The present study focuses on the verification of the swirling jet effect on the distribution of the local heat transfer coefficient on the impinged target surface. Studies would be conducted for a wide range of parameters including velocity, swirl Pitch and nozzle to target plane spacing. The motivation of this paper is to explore the efficiency of swirling jet impingement cooling and understand the mechanisms by which heat is removed from a constant heat flux surface. The heat transfer characteristics and flow structures are explored computationally to gain an understanding of the underlying physics of flow and heat transfer interactions in surface cooling with impinging jets.

CFD Analysis of Heat Transfer and Characteristics of Swirl Flow Jet Impingement Cooling

Impinging jet is one of the ideal schemes to satisfy the heat dissipation requirement of the high power chips In this research, experiments are carried out to investigate the heat transfer between the straight impinging jet array and an iso-heat-flux simulant chip (a heated epoxy resin plate) In the heat transfer experiments, two kinds of jet array are considered, the circular array and the four square array In some range of flux of the air jet and nozzle-to-plate spacing, the influence of the different arrangement of the spout on average heat transfer of the target plate is discussed Furthermore, the heat transfer effect of the jet array is compared to the single orifice nozzle which has the same flow area with the array nozzle Meanwhile, numerical simulation is performed to study the heat transfer effect of the swirling impinging jet in this paper The angular velocity of the swirling jet, the flow Reynolds number, the dimension of the nozzle and the nozzle-to-plate spacings are examined, then the distribution of both local and average heat transfer coefficient (Nusselt number) on the simulant chip is obtained

Study on Compulsive Cooling of Straight Impinging Jet Array and Swirling Jet Impingement

The rapid miniaturization of the electronic packaging accelerated the development of air cooling technology. In this research, both experimental and numerical methods are adopted to investigate the heat transfer between the air swirling impinging jets and an iso-heat-flux simulant chip. In the experiment scheme, the simulant chip is impacted by the swirling jet which is generated by inserting twisted strips into round nozzles. In some range of flow Reynolds number, the effects of nozzle-to-plate spacement, the geometries of the nozzle and the thread intervals of the twisted strips are examined, and then the radial distributions of Nusselt numbers on the target plate are obtained. Meanwhile, the heat transfer characteristics of the swirling jet in both the stagnation region and the wall jet region are interpreted. In order to verify its heat transfer effect, the swirling jet is compared to the ordinary straight one. Afterwards, numerical simulation is also performed to study the heat transfer effect of this cooling system, in which, a simplified axisymmetric model is built. The angular velocity of the swirling jet, the flow Reynolds number, the dimension of the nozzle and the nozzle-to-plate spacings are all examined, and then the distribution of heat transfer coefficient (Nusselt number) on the simulant chip is also obtained.

Fu Yi-feng

Papers

Study on Compulsive Cooling of Straight Impinging Jet Array and Swirling Jet Impingement

Comparative Investigation on the Cooling Effect of Swirling Impinging Jet using Experimental and Numerical Methods