Results 1 - 10
of
75
Analysis of three-dimensional heat transfer in micro-channel heat sinks
- Int. J. Heat Mass Transfer
, 2002
"... In this study, the three-dimensional fluid flow and heat transfer in a rectangular micro-channel heat sink are ana-lyzed numerically using water as the cooling fluid. The heat sink consists of a 1-cm2 silicon wafer. The micro-channels have a width of 57 lm and a depth of 180 lm, and are separated by ..."
Abstract
-
Cited by 25 (2 self)
- Add to MetaCart
(Show Context)
In this study, the three-dimensional fluid flow and heat transfer in a rectangular micro-channel heat sink are ana-lyzed numerically using water as the cooling fluid. The heat sink consists of a 1-cm2 silicon wafer. The micro-channels have a width of 57 lm and a depth of 180 lm, and are separated by a 43 lm wall. A numerical code based on the finite difference method and the SIMPLE algorithm is developed to solve the governing equations. The code is carefully validated by comparing the predictions with analytical solutions and available experimental data. For the micro-channel heat sink investigated, it is found that the temperature rise along the flow direction in the solid and fluid regions can be approximated as linear. The highest temperature is encountered at the heated base surface of the heat sink immediately above the channel outlet. The heat flux and Nusselt number have much higher values near the channel inlet and vary around the channel periphery, approaching zero in the corners. Flow Reynolds number affects the length of the flow developing region. For a relatively high Reynolds number of 1400, fully developed flow may not be achieved inside the heat sink. Increasing the thermal conductivity of the solid substrate reduces the temperature at the heated base surface of the heat sink, especially near the channel outlet. Although the classical fin analysis method provides a simplified means to modeling heat transfer in micro-channel heat sinks, some key assumptions introduced in the fin method deviate significantly from the real situation, which may compromise the accuracy of this method. 2002
Effective cooling of integrated circuits using liquid alloy electrowetting
- in: Proceedings of the Semiconductor Thermal Measurement, Modeling, and Management Symposium (SEMI-Therm), IEEE
, 2005
"... Electrical modulation of surface tension is proposed for actuation and pumping of discrete droplets of liquid met-als/alloys for active heat management of Integrated Circuits (ICs) and removal of hot spots on any solid surface. The proposed technique is based on two observations: (i) By using liquid ..."
Abstract
-
Cited by 10 (3 self)
- Add to MetaCart
Electrical modulation of surface tension is proposed for actuation and pumping of discrete droplets of liquid met-als/alloys for active heat management of Integrated Circuits (ICs) and removal of hot spots on any solid surface. The proposed technique is based on two observations: (i) By using liquid metals or alloys at room temperature (instead of e.g. water or air) heat transfer rate of a cooling system can be enhanced significantly, (ii) Electrowetting is an efficient, low power consumption, and low voltage actuation technique for pumping liquids at micro-scales. These two ideas are employed in this investigation in order to design a novel active heat management technique for high-power-density electronic and integrated micro systems. Preliminary calculations indicate that more than two orders of magnitude increase in heat transfer rate could be achieved by using liquid metals as compared with systems using water as the coolant fluid. Liquid velocities above 10 cm/s is observed with extremely low pumping power consumption and at low actuation voltage (∼2 V). The current technique can be used for active heat management of ICs to detect and properly handle an over-heating event. It is expected that digitized electrowetting to offer a viable cooling strategy to achieve the most important objectives of electronic cooling; i.e. minimization of the maximum substrate temperature and reduction of the substrate temperature gradient and removing substrate hot spots1.
2006, “Implementation of microchannel evaporator for high-heat-flux refrigeration cooling applications
- J. Electronic Packaging
"... ..."
DESIGN OF A MICROFABRICATED RANKINE CYCLE STEAM TURBINE FOR POWER GENERATION
"... This paper presents the system-level and component design of a micro steam turbine power plant-on-a-chip which implements the Rankine cycle for micro power generation. The microfabricated device consists of a steam turbine that drives an integrated micropump and generator. Two-phase flow heat exchan ..."
Abstract
-
Cited by 3 (2 self)
- Add to MetaCart
(Show Context)
This paper presents the system-level and component design of a micro steam turbine power plant-on-a-chip which implements the Rankine cycle for micro power generation. The microfabricated device consists of a steam turbine that drives an integrated micropump and generator. Two-phase flow heat exchangers are also integrated on-chip with the rotating components to form a complete micro heat engine unit, converting heat to electricity. The system-level design includes cycle analysis and overall performance predictions, accounting for the expected performance of miniaturized components, thermal and structural integrity of the microsystem, and system-level trade-offs for optimal overall performance. Operating principles and design studies are also presented for the core component, with emphasis on a multistage, planar, radial microturbine and a spiral groove viscous pump. Design consideration for two-phase flow heat exchangers, microbearings, seals and micro-generators are also presented. Expected power levels range from 1-12 W per chip with energy conversion efficiency in the range of 1-11%. This suggests power density of up to 12 kW/kg for this technology, which is an order of magnitude greater than competing technologies, such as thermoelectrics. This study suggests the viability of a micro Rankine power plant-on-a-chip, but also identifies critical engineering challenges that must be met for practical implementation.
Heat Transfer in WaterCooled Silicon Carbide Milli-Channel Heat Sinks for High Power Electronic
- Applications,” J. Heat Transf
, 2005
"... ..."
Single-phase Hybrid Microchannel/Micro-jet Impingement Cooling
- International Journal of Heat and Mass Transfer
, 2008
"... Abstract A new hybrid cooling scheme is proposed for high-flux thermal management of electronic and power devices. This scheme combines the cooling benefits of micro-channel flow and micro-jet impingement with those of indirect refrigeration cooling. Experiments were performed to assess single-phas ..."
Abstract
-
Cited by 1 (0 self)
- Add to MetaCart
(Show Context)
Abstract A new hybrid cooling scheme is proposed for high-flux thermal management of electronic and power devices. This scheme combines the cooling benefits of micro-channel flow and micro-jet impingement with those of indirect refrigeration cooling. Experiments were performed to assess single-phase cooling performance using HFE 7100 as working fluid. Excellent predictions were achieved using the standard k-e model. The proposed cooling scheme is shown to involve complex interactions of impinging jets with micro-channel flow. Increasing jet velocity allows jets to penetrate the micro-channel flow toward the heated surface, especially in shallow micro-channels, greatly decreasing wall temperature. Despite the relatively poor thermophysical properties of HFE 7100, the proposed cooling scheme facilitated the dissipation of 304.9 W/cm 2 without phase change; further improvement is possible by increasing jet velocity and/or decreasing coolant temperature. In addition to the numerical predictions, a superpositioning technique is introduced that partitions the heat transfer surface into zones that are each dominated by a different heat transfer mechanism, and assigning a different heat transfer coefficient value to each zone. Using this technique, a new correlation is developed that fits the data with a mean absolute error of 6.04%.
Assessment of Thermal Behavior and Development of Thermal Design Guidelines for Integrated Power Electronics Modules
, 2005
"... With the increase dependency on electricity to provide correct form of electricity for lightning, machines, and home and office appliances, the need for the introduction of high reliability power electronics in converting the raw form of electricity into efficient electricity for these applications ..."
Abstract
-
Cited by 1 (0 self)
- Add to MetaCart
(Show Context)
With the increase dependency on electricity to provide correct form of electricity for lightning, machines, and home and office appliances, the need for the introduction of high reliability power electronics in converting the raw form of electricity into efficient electricity for these applications is uprising. One of the most common failures in power electronics is temperature related failure such as overheating. To address the issue of overheating, thermal management becomes an important mission in the design of the power electronics to ensure the functional power electronics. Different approaches are taken by academia and industry researchers to provide efficient power electronics. In particular, the Center for Power Electronics System (CPES) at Virginia Tech and four other universities presented the IPEM approach by introducing integrated power electronics modules (IPEM) as standardized units that will enable greater integration within power electronics systems and their end-use application. The IPEM approach increases the integration in the components that make up a power electronics system through novel a packaging technique known as Embedded Power
MicroPatterned Substrates with Nano-Scale Elements for Pool Boiling
- Proceedings of the ASME/JSME 2011 8th Thermal Engineering Joint Conference, ASME
, 2011
"... The critical heat flux values of copper substrates were increased from 87 to 125 W/cm2 by using a simple chemical process resulting in growth of micro and nano-scale copper structures on the surface. Pre- and post-test surface analysis revealed that the morphology of the micro and nano-scale feature ..."
Abstract
-
Cited by 1 (1 self)
- Add to MetaCart
(Show Context)
The critical heat flux values of copper substrates were increased from 87 to 125 W/cm2 by using a simple chemical process resulting in growth of micro and nano-scale copper structures on the surface. Pre- and post-test surface analysis revealed that the morphology of the micro and nano-scale features of these copper structures changed during the boiling process accompanied by a change in oxide layer composition. Boiling performance of the micro and nano-structured samples was repeatable when testing at lower heat fluxes.
Feedback stabilisation of two-dimensional non-uniform pool-boiling states
- in Heat Transfer XI
, 2010
"... Abstract In this paper the feedback stabilisation of a two-dimensional pool-boiling system is discussed. The pool-boiling system is modelled by a so-called heater-only model, which consists of a Partial Differential Equation (PDE) which describes the heaters internal temperature field and its (nonl ..."
Abstract
-
Cited by 1 (1 self)
- Add to MetaCart
(Show Context)
Abstract In this paper the feedback stabilisation of a two-dimensional pool-boiling system is discussed. The pool-boiling system is modelled by a so-called heater-only model, which consists of a Partial Differential Equation (PDE) which describes the heaters internal temperature field and its (nonlinear) boundary conditions given by the heat exchange between fluid and heater at the top and the heat supply at the bottom of the heater. The pool-boiling system is extended with an adjustable heat supply at the bottom of the heater, by which the unstable transition boiling regime is to be stabilised. Thereto, a feedback law, based on the Chebyshev-Fourier-cosine modes of the spectral discretisation of the temperature profile inside the heater, is applied to the system. The control parameters of this feedback law are designed such that satisfactory closed-loop dynamics are obtained. Using this specific feedback law, the control strategy is tested by simulations of the closed-loop pool-boiling system.
Two-phase flow boiling in small – to micro – diameter tubes
, 2008
"... reach of exact prediction because of the variety of factors in operation, not because of any lack of order in nature. " ..."
Abstract
-
Cited by 1 (1 self)
- Add to MetaCart
reach of exact prediction because of the variety of factors in operation, not because of any lack of order in nature. "
