Electronics cooling

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

Reset control of pressure-drop oscillations in boiling micro-channel systems

Abstract: A micro-channel has become a popular scheme in high heat flux electronics cooling. But boiling flow instabilities can occur in these cooling systems with micro-channel heat sinks. These pressure-drop oscillations are limit cycles. We model the system by a van der Pol equation with a control input, which is represented by a control system with a nonlinear feedback element. Using a describing function, we approximate the pressure-drop oscillation in the boiling micro-channel system controlled by a reset controller. Then we obtain a control parameter region where the pressure-drop oscillation is eliminated by the controller. By simulation, we also show that the pressure-drop oscillation is eliminated by the reset controller.

CAD-based methods for thermal modeling of coolant loops and heat pipes

Abstract: As air cooling of electronics reaches the limits of its applicability, the next generation of cooling technology is likely to involve heat pipes and single- or two-phase coolant loops. These technologies are not suitable for analysis using 2D/3D computational fluid dynamics (CFD) software, and yet the geometric complexities of the thermal/structural models make network-style schematic modeling methods cumbersome. This paper describes CAD line-drawing methods to quickly generate 1D fluid models of heat pipes and coolant loops within a 3D thermal model. These arcs and lines can be attached intimately or via lineal contact or saddle resistances to plates and other surfaces, whether those surfaces are modeled using thermal finite difference methods (FDM) or finite element methods (FEM) or combinations of both. The fluid lines can also be manifolded and customized as needed to represent complex heat exchangers and plumbing arrangements. To demonstrate these concepts, two distinct examples are developed: a copper-water heat pipe, and an aluminum-ammonia loop heat pipe (LHP) with a serpentined condenser. A summary of the numerical requirements for system-level modeling of these devices is also provided.

Identifying Hot Spots in Electronics Packages with a Sensitivity-Coefficient Based Inverse Heat Conduction Method

Abstract: Inverse heat conduction methods can be used to estimate the location and intensity of heat sources in electronics, but often there is a tradeoff in computational cost and accuracy of the retrieved heat fluxes and temperatures. This is exacerbated when the exact size and locations of heat sources within the device are unknown. This paper demonstrates the applicability of an inverse sensitivity coefficient method to locate hotspots and estimate associate hot spot temperatures for a commercial electronics package. The sensitivity coefficients are computed with a steady-state, 3-D finite volume model in FloTHERM. In this work, the locations and sizes of the heat sources are not initially known, thus, we impose a grid of potential heater source locations on one surface, and activate the heaters located under the hot spots visible in the temperature profile. The inverse model is validated with the results of a “numerical experiment” (i.e., solving the direct problem in FloTHERM and using the temperature maps as input to the inverse solver) and used to identify hot spots in a commercial device using temperature maps acquired experimentally with infrared microscopy. While demonstrated here for a microelectronic device, this method is broadly applicable to other systems where the distribution of heat generation is unknown and limited only temperature measurements are experimentally possible including batteries and manufacturing processes.

Electronic cooling technology with use of turbulent impinging jets

Abstract: An investigation on cooling of the solid surface was performed by studying the behaviors of impinging jets onto a fixed flat plate. The flow and local heat transfer coefficient distributions on a plate with a constant heat source were numerically investigated with a normally impinging axisymmetric jet. Numerical predictions of the mean velocities across the jet were. Made with several different nozzle-to-plate stand-off distances were considered. The two-dimensional cylindrical Navier-Stokes equations were solved using a two-equation turbulence model of the k-/spl epsi/ model version. The finite-volume differencing (FVD) scheme was used to solve the thermal and flow fields. The predicted velocities and heat transfer coefficients were compared with previously obtained experimental measurements. A universal function based on the wave equation was developed and applied to the heat transfer model to improve calculated local heat transfer coefficients. Predictions by the present model show good agreement with the experimental data.

Microscale technology electronics cooling overview

Abstract: NASA requirements and subsequent technology solutions for high heat flux electronics are generally different that those for the terrestrial applications. Unlike terrestrial operations. NASA spacecraft have limited opportunities for air cooling, for example, and must rely on less efficient thermal radiation to reject heat to space. The terrestrial commercial electronics industry, as well as other Government agencies, is investing in advanced technologies for electronics cooling at the microscale. This paper gives a brief summary of metrics used in high heat flux electronics cooling, the difference between solutions developed for terrestrial requirements and those for space, and a short description of challenges as well as possible solutions for space-based high heat flux electronics cooling. The argument is made that high heat flux electronics cooling is indeed a core technology required by NASA, since the thermal and other environmental requirements are unique to NASA space missions and are not addressed ...