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Showing papers on "Electronics cooling published in 1993"


Journal ArticleDOI
TL;DR: In this paper, a mathematical formulation for periodically fully developed natural convection with thermally active throughflow is presented in the context of the flow through an insulated channel with heated blocks mounted on one of the walls.

35 citations


Proceedings ArticleDOI
02 Feb 1993
TL;DR: In this paper, an analytical solution for the temperature field which arises from the application of a source of heat on an adiabatic plate or board when the fluid is represented as a uniform flow with an effective turbulent diffusivity, the so-called UFED flow model is presented.
Abstract: Analytical solutions are presented for the temperature field which arises from the application of a source of heat on an adiabatic plate or board when the fluid is represented as a uniform flow with an effective turbulent diffusivity, the so-called UFED flow model. Solutions are summarized for a point source, a one-dimensional strip source, and a rectangular source of heat. The ability to superpose the individual kernel solutions to obtain the temperature field due to multiple sources is demonstrated. The point source solution reveals that the N/sup -1/ law commonly observed for the centerline thermal wake decay for three-dimensional arrays is predicted by the point source solution for the UFED model. The thermal wake approaches the point source behavior downstream from the source, suggesting a new scaling for the far thermal wake that successfully collapses the thermal wake for several sizes of components and provides a fundamental basis for experimental observations previously made for arrays of three-dimensional components. Preliminary experimental results using a thermochromic liquid crystal thermal mapping technique are presented. >

18 citations


Journal ArticleDOI
TL;DR: In this paper, accurate numerical calculations have been conducted for buoyancy-driven two-dimensional flow of air between two vertical parallel isothermal plates, of aspect ratio 1, placed inside a rectangular enclosure.
Abstract: Accurate numerical calculations have been conducted for buoyancy-driven two-dimensional flow of air between two vertical parallel isothermal plates, of aspect ratio 1, placed inside a rectangular enclosure. The Grashof number based on the channel half width is 105 . Insights have been obtained regarding the structure of the transient flow and thermal fields in a configuration of particular interest to electronics cooling. In the early stages of the transient the flowfield was found to be highly vortical and the net volume flow rate in the channel displayed an oscillatory behavior, periodically reversing its direction. However, the velocity profile adjacent to the heated plates maintained the same direction throughout the process, and hence the Nusselt number was relatively insensitive to the periodic flow reversal in the channel. Detailed studies of the transient flow field and the heat transfer results are presented.

15 citations


Journal ArticleDOI
J.M. Hogan1
TL;DR: In this paper, a tractable model for predicting the failure rates of electronic chassis cooled by fans with finite failure rates is developed, which directly applies to cost/benefit studies in electronics packaging, including the determination of the improvement in mean time between failures (MTBF) to be anticipated when a chassis is implemented with a cooling fan.
Abstract: A tractable model for predicting the failure rates of electronic chassis cooled by fans with finite failure rates is developed. The model accounts for two regimes prior to electronics failure: the electronic chassis is operated at a temperature which occurs with a fan that is operational and the electronic chassis is operated at a temperature which occurs when the fan has failed. Fan failures alone do not constitute a failure of the chassis. Such a model applies where cooling fans are not actively monitored, and where their failure is noticed only during the maintenance associated with an electronic failure of the chassis, i.e., the model accounts for the fact that the electronics in general continues to operate for a period of time following a fan failure. The model directly applies to cost/benefit studies in electronics packaging, including the determination of the improvement in mean time between failures (MTBF) to be anticipated when a chassis is implemented with a cooling fan, and the determination of the performance benefit to be anticipated when fans are actively monitored and replaced upon failure. >

7 citations