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In this research, we evaluate the potential for air cooling to meet the stringent cooling requirements of advanced automotive power electronics. We assess air cooling of power electronic components using laminar airflow micro-channel heat exchangers. Comparisons are made with ethylene glycol systems commonly used in tandem with engine cooling. Our analysis shows that despite a lower coefficient of...
Large density differences between liquid and vapor create buoyancy effects in the presence of a gravitational field. Such effects can play an important role in two-phase fluid flow and heat transfer, especially critical heat flux (CHF). CHF poses significant risk to electronic devices, and the ability to predict its magnitude is crucial to both the safety and reliability of these devices. Variations...
Thermal performance of a high-power (>1 kW peak) automotive electronics module was evaluated using ANSYS' ICEPAKtrade Computational Fluid Dynamics (CFD) software. The module exchanges heat with cooling air via a plate-finned aluminum heat sink. To confirm the CFD model, the numerical air exit temperature results are compared to that of using the mass flow heat transfer equation. Additionally, convection...
Design features and experimental results are presented for a heatsink with the thermo-siphon structure for cooling multi- chip modules. The prototype heatsink was made, which consists of copper tubes, stainless container, PF-5060 as a coolant and rubber heaters for simulating multi-chip modules, and some basic experiments were carried out to obtain the cooling performance of the heatsink with the...
A numerical investigation was performed at two Reynolds numbers to compare the flow and heat transfer characteristics for a pair of parallel impinging slot jets in 2D and 3D. The present study continues the authors' earlier work [1], and identifies the main similarities and differences arising from the expansion to the third dimension. For comparison purposes, a couple of slot jets impinge on two...
As portable platforms including laptops, handheld PCs, and similar handheld electronics become more powerful and more popular, they present unique thermal management challenges. In the past, most thermal management solutions have dealt with directly cooling the microprocessor by way of a heat spreader, heat sink, and fan. However, the microprocessor thermal solution does not cool all areas of the...
This study examines numerically details of the flow and temperature fields of heat sinks with short plate fins cooled by impinging jet. The main focus is on the effect of fin shapes on the heat sink performance. Conjugate heat transfer between airflow convection and conduction inside the fin and base is considered. Three different shapes under study are rectangular, round-headed and elliptic, while...
Experiments are carried out to investigate heat transfer enhancement from a heated square cylinder in a channel by pulsating flow. For all the experiments, the amplitude of the pulsating flow is fixed at A = 0.05. The vortex shedding frequency and the time-averaged Nusselt number are measured for various gap height (S/D = 3.5, 2.0, 1.5, 1.0 and 0.75) at Reynolds number Re = 700. The influences of...
The dimensions and power dissipation information of various commercial handheld electronics were collected to find benchmarking size and power ranges. The relationship between device size parameter, defined as total volume divided by external surface area, and the power dissipation was determined. Three dimensional finite element models were used to model the conduction, natural convection, and surface-to-surface...
Fluid flow and mixed (free and forced) convection heat transfer characteristics over a micro-sphere at moderate to high values of both Grashof and Reynolds numbers are numerically investigated at uniform wall temperature boundary condition. Although this topic is crucial in understanding the basic flow and heat transfer features about a miniature sphere, little attention was drawn into it in the open...
3D interconnect technology has attracted significant interest in the recent past as a means for enabling faster and more efficient integrated circuits (ICs). 3D integration relies on through-silicon vias (TSVs) and bonding of multiple active layers. While this approach provides several electrical benefits, it also offers significant challenges in thermal management. While some work has been done in...
This paper is a continuation of the study (Iyengar et al., 2007) that describes the comparison of numerically-predicted and experimentally- measured temperature distributions in a small data center test cell. The data center cell has a floor area of 900 ft2 and comprises one rack, one air-conditioning unit, and perforated tiles. The Computational Fluid Dynamics (CFD) results in study (Iyengar et al...
Boiling heat transfer enhancement for a two-phase cooling design is presented in this paper. The paper discusses an effective method of boiling heat transfer enhancement and its performance. The pool boiling heat transfer from the silicon surface is enhanced by combination of surface modification and micro machined structure. The effect of micro structure features like pore diameter, pore pitch, channel...
In this study, confinement-driven boiling enhancement trends and experimental data from narrow parallel plate channels are presented and analyzed via comparison with numerical simulations of buoyancy-driven boiling and two phase flow using the commercially-available Fluent CFD software package. An Euler-Euler multiphase approach, known as the volume of fluid (VOF) method, is employed, as bubbles sizes...
With the relentless trend of increasing power and decreasing dimensions, thermal management of electronic packages is becoming a critical issue. Existing cooling techniques are fast becoming inadequate for the powerful electronic components expected in the near future. Researchers all over the world have been experimenting with advanced cooling techniques such as spray and impingement cooling using...
The effects of vortex generators (VG's) on fluid flow and heat transfer have been studied extensively in the literature. The majority of these studies have examined the effects of using VG's in heat exchanger applications. Other investigations have examined the role of placing VG's in channel flow or on a heated flat plate owing to the fact that these experimental set-ups facilitate easy comparison...
microchannel heat sinks are considered a strong candidate for meeting the increasing cooling needs of high-power microprocessors of today and the significant future. Such heat sinks are capable of dissipating impressive amounts of energy, as a result of high attainable heat transfer and favorable heat transfer surface area to volume ratios. The majority of microchannel heat sink studies performed...
Many factors, such as acoustic noise limits and fan reliability considerations, limit the heat dissipation capacity of air-cooled cabinets housing telecommunications or computing hardware. The present work examines the potential of enhanced cooling in a sealed telecommunications cabinet using an evaporating- condensing dielectric mist introduced upstream of heat sinks attached to high-power components...
Experiments were performed to investigate spray cooling enhancement on micro-structured surfaces. Surface modification techniques were utilized to obtain micro-scale indentations and protrusions on the heater surfaces. A smooth surface was also tested to have baseline data for comparison. Tests were conducted in a closed loop system with ammonia using RTFs vapor atomized spray nozzles. Thick film...
This study examines the heat transfer enhancement attributes of carbon nanotubes (CNTs) applied to the bottom wall of a shallow rectangular micro-channel. Using deionized water as working fluid, experiments were performed with both a bare copper bottom wall and a CNT-coated copper wall. Boiling curves were generated for both walls, aided by high-speed video analysis of interfacial features. CNT arrays...
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