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Rapid development in the design of electronic packages for modern high-speed computers has led to the demand for effective methods of chip cooling. The primary concerns in thermal management applications are high thermal conductivity, large specific surface area and low weight. Graphite foams which possess predominantly spherical pores with smaller openings between the cells constitute a novel highly-conductive...
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...
A pressure atomized evaporative spray cooling nozzle array was used to thermally manage the power electronics of a 3 phase inverter module. The module tested was a COTS module manufactured by Semikron, Inc., and has a maximum DC power input of 180 kW (450 VDC and 400 A) with 25degC coolant. However, the standard heat sink that the module uses is a single phase liquid heat sink and when 100degC coolant...
In natural convection applications, the components used for cooling may represent a significant portion of the overall weight of the system. Consequently, advanced materials are of interest in such applications, as they may substantially reduce the total size and the weight of the system. Many of these advanced materials have anisotropic thermo physical properties, hence the control of thermal conductivity...
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...
In the electronics cooling literature, the use of the overall thermal resistance to describe the thermal performance of cooling technologies, has hindered the adoption of more robust and powerful thermal performance metrics, most notably the heat exchanger effectiveness, epsiv , that arises in the theory of heat exchangers. This paper presents a theoretical treatment of the heat transfer in cold plates...
In recent years the design of portable electronic devices must incorporate thermal analyses to ensure the device can be adequately cooled to acceptable temperatures. Consumer demand for smaller, more powerful devices has lead to an increase in the heat required to be dissipated and a reduction in the surface area both of which result in an increased heat flux. In this paper, an experimental study...
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...
Nano fluids are colloidal solutions which contain a small volume fraction of suspended submicron particles or fibers in heat transfer liquids, such as water or glycol mixtures. Compared with the base fluid, numerous experiments have generally indicated an increase in effective thermal conductivity and a strong temperature dependence of the static effective thermal conductivity. However, in practical...
For a given heat sink thermal resistance and ambient temperature, the temperature of an electronic device rises fairly linearly with increasing device heat flux. This relationship is especially problematic for defense electronics, where heat dissipation is projected to exceed 1000 W/cm2 in the near future. Direct and indirect low temperature refrigeration cooling facilitate appreciable reduction in...
This study compared thermal-hydraulic performance of a single-phase micro-pin-fin heat sink with that of a micro-channel heat sink having the same characteristic dimensions and operating under the same conditions. The objective was to explore the potential of micro-pin-fin heat sinks as an effective alternative to micro-channel heat sinks for dissipating high-heat-fluxes from small areas. The micro-pin-fin...
A novel vapor chamber is proposed and tested in this study. Multi-layer copper mesh is sintered to the inner surface of the bottom plate as the evaporator wick. Parallel channels, with inter-channel openings, are made on the inner surface of the top plate. The peaks of the channel walls directly contact with the wick so that the channels function as vapor path, condenser and structural supporters...
Thermal performance of louver fin, offset strip fin and plate fin in a thermoelectric cooling system with a duct-flow type fan arrangement is analytically examined. The thermoelectric cooling system is composed of a water jacket, an array of thermoelectric modules and a heat sink. Heat sinks with dimension of 39.7 mm times 119.1 mm plane area and 40 mm fin height are considered for the performance...
To address the thermal management challenges associated with high power dissipation devices, we describe a novel hybrid thermal management device, which enables significant enhancement of conventional air-cooled heat sinks using on- demand and spatially controlled droplet/jet impingement evaporative cooling. The device architecture modifies an air (gas)-cooled heat sink by adding a multiplexed, planar...
Chip-level heat flux levels have risen beyond 250 W/cm2 due to the presence of circuit architecture-driven hot-spots. After intense scrutiny over the past two decades, microchannel heat sinks are closer to commercial implementation as evidenced by the advent of the single-chip silicon cooler announced recently by IBM. Though there are a multitude of studies and data related to multichannel configurations,...
The merits of water-fed microchannel heat sinks have shown that the technology may be a plausible and effective cooling solution for the ever-increasing power dissipation of high speed microprocessors. Favorable factors such as high heat transfer surface area and heat flux removal for reasonable operating pressures, as well small heat sink mass and volume continue to drive the technology. However,...
Thermal management of device level packaging continues to present many technical challenges. In the typical chip heat sink assembly, the highest resistance to heat flow comes from the thermal interface material (TIM). The thermal conductivities of TIMs remain in the range of 1-4 W/mK due to the properties and structure of small dispersed solids in polymer matrices. As a result of the rising design...
The ever-increasing size of wireless networks has led to the development of new base station architectures. Traditional telecommunication base stations have baseband and radio-frequency (RF) components mounted inside an air-conditioned hut with co-axial cables transmitting signals to remote antennas. The industry is moving to distributed network and remote radio head (RRH) architectures where the...
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...
In this paper, a novel heat sink with moving fins inserted between cooling fins is suggested for electronics cooling applications. In the novel heat sink, instead of the fan module, moving fins are inserted in the intervals of fixed fins (cooling fins) for generating fluid flow. By the relative motion of the moving fins to the cooling fins, heat dissipation from the cooling fins to the coolant and...
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