Electronics cooling

About: Electronics cooling is a research topic. Over the lifetime, 1135 publications have been published within this topic receiving 17608 citations.

On the miniaturisation of convenction cooling solutions applicable to portable electronic devices

Abstract: Dimensional restrictions in electronic equipment have resulted in miniaturisation of many existing cooling technologies. In addition, cooling solutions are required to dissipate increased thermal loads to maintain component reliability and user comfort. Fans are widely used in electronics cooling to meet such thermal demands, either in standalone for direct component cooling, or in combination with a heat sink. The thermal performance of such designs when scaled to dimensions suitable for use in portable electronics has received limited attention, mainly due to the reliance on passive cooling methodologies currently employed. However, as heat flux increases, passive cooling is reaching its limit and other solutions will be required. This thesis aims to address this issue by experimentally examining the fluid dynamics and thermal performance of forced convection cooling solutions with dimensional constraints. Conventional finned and novel finless heat sink designs have been integrated with commercially available radial blowers to investigate cooling solutions with overall foot print areas as low as 487mm2, and profile heights less than 5mm. The novel finless geometry, with reduced manufacturing cost, energy consumption and weight promoted heat transfer above that of the same size classical finned designs for a range of operating points. Both geometries showed increases of up to 20% in thermal performance by aligning the fan exit flow with the heat sink channels, hence demonstrating the need for integrated fan and heat sink design of low profile applications. Optimisation and geometry selection criteria were determined by scaling profile height for both heat sink designs from 4mm to 1mm. Theoretical predictions under estimated the finless design thermal performance, which was found to scale towards that of a turbulent flow regime despite the low Reynolds number. The mechanisms of this improvement in heat flux was investigated and unique, heat transfer enhancing, features in the finless design were identified. A combined infrared thermography and heated-thin-foil technique was developed for miniature fan applications, to accurately determine local heat transfer coe cients due to radial and axial fan flows. This highlighted the non-uniform heat transfer rates produced by the three-dimensional air patterns from rotating fans, and has been shown to be an important consideration in the design stages for component cooling. For the same chip temperature, strategic positioning of electronic components resulted in up to three-fold gains in power dissipation for direct component cooling applications. Local peaks in heat transfer coe cient when using axial fan impingement were directly related to the air flow and fan motor support interaction. It was found that for optimum thermal performance, motor support dimensions should be kept to a minimum and positioned on the inlet flow plane, the opposite to the current industrial practice. Flow structures and surface heat transfer trends due to radial fan flows were found to be common…

CPU Cooling by Vapor Chamber with R-141b as Working Fluid

Abstract: Air cooling and the space limitations are encountered problems of the thermal cooling electronic development for electronics devices or computer. In the present study, results of the experimental investigation on the thermal cooling of vapor chamber with refrigerant R-141b as working fluid for cooling computer processing unit of the personal computer are presented. Parametric studies including different aspect ratios, fill ratios, and operating conditions of PC on the thermal cooling are considered. Average CPU temperatures obtained from the vapor chamber cooling system with R-141b are 19.55%, 18.61% lower than those from the conventional cooling system for no load and 90% operating loads, respectively. In additional, this cooling system requires 50% lower energy consumption for no load operating loads.

Reduction of boiling thermal hysteresis in immersed electronics cooling on micro-configured graphite-metal conposite surfaces

Abstract: It is known that hysteresis is an important and unique dynamic characteristics in two-phase systems in motion with or without rotation In pool boiling which generates vapor phase, the system is set in motion due to a pumping action near the heating surface caused by the departure of bubbles whose space is replaced by the surrounding liquid body However, its dynamic behavior at the same surface superheat differs when the boiling heat flux undergoes an increasing trend and when it undertakes a decreasing trend The discrepancy in a boiling curve is generally recognized as boiling hysteresis which is especially evident in boiling of a highly wetting liquid The present work investigates (i) difference in the start-up/restart cycles between the micro-configured graphite fiber-metal composite surface and pure metal surface, and (ii) mechanism for reduction of boiling thermal hysteresis on the composite surfaces The graphite fiber surfaces possess two distinguished properties that are suitable to avoid retardation of bubble nucleation in highly wetting electronics cooling liquids One is their ill-wetted character for most liquids and the other is their high thermal conductivity

Thermal Performance of Microchannels With Dimples for Electronics Cooling

Abstract: The thermal management of integrated circuits becomes more and more serious since the density of transistors grows gradually. Recently, a new cooling method is dedicated to develop microchannel heat sink with high integrated and high cooling efficiency. In view of above purpose, the heat transfer enhancement and pressure drop reduction in microchannel with dimples are investigated in this paper. A single module of 1mm×1mm×20mm with a microchannel was employed, which hydraulic diameter and aspect ratio are 500 μm and 2:1 respectively. For replacing the running integrated circuits, a constant heat flux of 1W/mm2 was arranged on the bottom of the heat sink. Six different types of microchannels with dimples were designed and numerically studied under the condition of laminar flow. The results show that dimple could enhance heat transfer and decrease flow resistance under the condition of laminar flow. Compared with traditional microchannel heat sink, dimple-microchannel heat sink has stronger cooling capacity, could be an attractive choice for cooling of future microelectronics.Copyright © 2013 by ASME