Showing papers on "Heat sink published in 2004"

Fuel-Cooled Thermal Management for Advanced Aeroengines

Abstract: Fuel-cooled thermal management, including endothermic cracking and reforming of hydrocarbon fuels, is an enabling technology for advanced aero engines and offers potential for cycle improvements and pollutant emissions control in gas turbine engine applications. The successful implementation of this technology is, however, predicated on the use of conventional multicomponent hydrocarbon fuels and an understanding of the combustion characteristics of the reformed fuel mixture. The objective of this research is to develop and demonstrate the technologies necessary for utilizing conventional multicomponent hydrocarbon fuels for fuel-cooled thermal management, including the development of the endothermic potential of JP-7 and JP-8 +100, a demonstration of the combustion of supercritical/endothermic fuel mixtures, and conceptual design of a fuel-air heat exchanger. The ability to achieve high heat sinks with existing jet fuels (e.g., JP-7 and JP-8 +100) was demonstrated with a bench-scale test rig operating under flow conditions and passage geometries simulative of practical heat exchangers for aircraft and missile applications. Key measurements included fuel heat sink, reaction products, and extent of conversion: Full-scale sector rig tests were conducted to characterize the combustion and emissions of supercritical jet fuel, and demonstrate the safety and operability of the fuel system, including a fuel-air heat exchanger.

Methods and apparatus for an LED light

Abstract: An LED lighting device for use in place of a commercial-standard light bulb. For example, a commercial-standard light bulb typically has an outer surface profile, generally defining its shape and the LED lighting device has its own surface profile which substantially mimics the surface profile of the commercial-standard light bulb. Additionally, LED lighting device may further comprise a heat sink for dissipating energy generated by the LED lighting device. In accordance with various embodiments, the heat sink creates the LED lighting device's outer surface profile and is configured to substantially mimic the outer surface profile of the commercial-standard light bulb.

Thermal management systems and methods

Abstract: A thermal management system for a vehicle includes a heat exchanger having a thermal energy storage material provided therein, a first coolant loop thermally coupled to an electrochemical storage device located within the first coolant loop and to the heat exchanger, and a second coolant loop thermally coupled to the heat exchanger. The first and second coolant loops are configured to carry distinct thermal energy transfer media. The thermal management system also includes an interface configured to facilitate transfer of heat generated by an internal combustion engine to the heat exchanger via the second coolant loop in order to selectively deliver the heat to the electrochemical storage device. Thermal management methods are also provided.

Personal heat control device and method

Abstract: Methods and apparatus for personal heat control are provided. According to one embodiment of the present invention, a self-contained, portable heat control device includes a flexible enclosure, a cooling surface, a heating surface, and a heat transfer unit, such as a Peltier-effect unit. The flexible enclosure, made of one or more bonded layers of polyester foam or a similar soft-faced material, is configured to accommodate an internal DC power supply. The heating surface is thermally insulated from the cooling surface. The heat transfer unit is accommodateed in or on the flexible enclosure and is configured and disposed to cool the cooling surface and heat the heating surface.

Micromachined jets for liquid impingement cooling of VLSI chips

Abstract: Two-phase microjet impingement cooling is a potential solution for removing heat from high-power VLSI chips. Arrays of microjets promise to achieve more uniform chip temperatures and very high heat transfer coefficients. This paper presents the design and fabrication of single-jets and multijet arrays with circular orifice diameters ranging from 40 to 76 /spl mu/m, as well as integrated heater and temperature sensor test devices. The performance of the microjet heat sinks is studied using the integrated heater device as well as an industry standard 1 cm/sup 2/ thermal test chip. For single-phase, the silicon temperature distribution data are consistent with a model accounting for silicon conduction and fluid advection using convection coefficients in the range from 0.072 to 4.4 W/cm/sup 2/K. For two-phase, the experimental results show a heat removal of up to 90 W on a 1 cm/sup 2/ heated area using a four-jet array with 76 /spl mu/m diameter orifices at a flowrate of 8 ml/min with a temperature rise of 100/spl deg/C. The data indicate convection coefficients are not significantly different from coefficients for pool boiling, which motivates future work on optimizing flowrates and flow regimes. These microjet heat sinks are intended for eventual integration into a closed-loop electroosmotically pumped cooling system.

Single-Phase Heat Transfer Enhancement Techniques in Microchannel and Minichannel Flows

Abstract: The single-phase heat transfer enhancement techniques are well established for conventional channels and compact heat exchangers. The major techniques include flow transition, breakup of boundary layer, entrance region, vibration, electric fields, swirl flow, secondary flow and mixers. In the present paper, the applicability of these techniques for single-phase flows in microchannels and minichannels is evaluated. The microchannel and minichannel single-phase heat transfer enhancement devices will extend the applicability of single-phase cooling for critical applications, such as chip cooling, before more aggressive cooling techniques, such as flow boiling, are considered.

System and method using self-assembled nano structures in the design and fabrication of an integrated circuit micro-cooler

Abstract: Heat sink structures employing carbon nanotube or nanowire arrays to reduce the thermal interface resistance between an integrated circuit chip and the heat sink are disclosed. Carbon nanotube arrays are combined with a thermally conductive metal filler disposed between the nanotubes. This structure produces a thermal interface with high axial and lateral thermal conductivities.

Building heat transfer

Abstract: Preface.Acknowledgements.1 Elementary Steady-State Heat Transfer.1.1 Human Thermal Comfort.1.2 Ambient Temperature.1.2.1 Design Temperature.1.2.2 Degree-Day Value.1.3 The Traditional Building Heating Model.1.3.1 Ventilation Loss.1.3.2 Conduction Loss.1.3.3 Loss from a Cylinder.1.4 Seasonal Heat Need.1.5 Plan of the Book.2 Physical Constants of Materials.2.1 Thermal Parameters for Gases: Kinetic Theory.2.2 Representative Values for Solids.2.3 Discussion.2.4 Appendix: The Maxwellian Distribution.3 Conduction-Dominated Systems.3.1 Heat Flow along a Fin.3.2 Heat Loss from a Solid Floor.3.2.1 One-Dimensional Heat Loss.3.2.2 Two-Dimensional Heat Loss.3.2.3 Three-Dimensional Heat Loss.3.2.4 Discussion of Floor Losses.3.2.5 Placement of Insulation.3.2.6 Heat Flow through Corners.3.3 Solution using the Schwarz-Christoffel Transformation.3.4 Appendix: Systems of Orthogonal Circles.4 Thermal Circuit Theory.4.1 Basic Thermal Elements.4.1.1 Reference Temperature.4.1.2 Temperature Node.4.1.3 Pure Temperature Source.4.1.4 Pure Heat Source.4.1.5 Conductance.4.1.6 Switch.4.1.7 Quasi Heat Source.4.1.8 Quasi Temperature Source.4.2 The Heat Continuity Equation in an Enclosure.4.2.1 The Mesh Approach.4.2.2 The Nodal Approach.4.3 Examples.4.3.1 The Ventilated Cavity.4.3.2 A Basic Circuit for Thermal Response.4.4 Circuit Transforms.4.4.1 Th venin's and Norton's Theorems.4.4.2 Delta-Star Transformation.4.4.3 Series-Parallel Transformation.5 Heat Transfer by Air Movement.5.1 Laminar and Turbulent Flow.5.2 Natural Convection: Dimensional Approach.5.2.1 Vertical Surface.5.2.2 Inclined Surface.5.2.3 Horizontal Surface.5.3 Natural Convection at a Vertical Surface: Analytical Approach.5.3.1 Heat Transfer through a Laminar Boundary Layer.5.3.2 Discussion of the Laminar Flow Solution.5.3.3 Heat Transfer through a Vertical Turbulent Boundary Layer.5.4 Natural Convection between Parallel Surfaces.5.5 Convective Exchange at Room Surfaces.5.6 Convective Exchange through an Aperture between Rooms.5.7 Heat Exchange at an External Surface.6 Heat Transfer by Radiation.6.1 The Fourth-Power Law.6.2 Emissivity, Absorptivity and Reflectivity.6.3 Radiation View Factors.6.3.1 Basic Expression for View Factors.6.3.2 Examples of View Factors.6.3.3 View Factors by Contour Integration.6.4 Direct Radiant Exchange between Surfaces.6.4.1 Assumptions for Radiant Exchange.6.4.2 The Thermal Circuit Formulation.6.5 Radiant Exchange in an Enclosure.6.5.1 Net Conductance G DELTAjkbetween Two Nodes.6.5.2 Star Conductance Gjkor Resistance Rjk.6.5.3 Optimal Star Links.6.5.4 How Good is the Delta-Star Transformation?6.5.5 Discussion.6.5.6 Linearisation of the Driving Potentials.6.5.7 Inclusion of the Emissivity Conductance.6.6 Space-Averaged Observable Radiant Temperature.6.6.1 Space-averaged Observable Temperature due to an Internal Radiant Source.6.6.2 Space-averaged Observable Radiant Temperature due to Bounding Surfaces.6.7 Star-Based Model for Radiant Exchange in a Room.6.8 Representation of Radiant Exchange by Surface-Surface Links.6.9 Long-Wave Radiant Exchange at Building Exterior Surfaces.6.10 Appendix: Conductance between Rectangles on Perpendicular and Parallel Surfaces.7 Design Model for Steady-State Room Heat Exchange.7.1 A Model Enclosure.7.2 The Rad-Air Model for Enclosure Heat Flows.7.3 Problems in Modelling Room Heat Exchange.7.3.1 The Environmental Temperature Model.7.3.2 The Invalidity of Environmental Temperature.7.3.3 Flaws in the Argument.7.4 What is Mean Radiant Temperature?8 Moisture Movement in Rooms.8.1 Vapour Loss by Ventilation.8.2 Vapour Resistivity.8.3 Vapour Loss by Diffusion through Porous Walls.8.4 Condensation on a Surface.8.5 Condensation in a Wall: Simple Model.8.6 Condensation in a Wall: More Detailed Models.8.6.1 Condensation in Glass Fibre.8.6.2 The Sorption Characteristic for Capillary-Porous Materials.8.6.3 Moisture Movement in Capillary-Porous Materials.8.7 Appendix: The Saturated Vapour Pressure Relation.8.8 Appendix: Saturated Vapour Pressure over a Curved Surface.8.9 Appendix: Measures of the Driving Potential for Water Vapour Transport.8.10 Appendix: Mould Growth in Antiquity.9 Solar Heating.9.1 Factors Affecting Radiation Reaching the Earth.9.2 Earth's Orbit and Rotation.9.3 The Sun's Altitude and Azimuth.9.4 Intensity of Radiation.9.5 Solar Incidence on Glazing.9.6 The Steady-State Solar Gain Factor.9.7 Solar Gain Contribution to Heat Need.10 The Wall with Lumped Elements.10.1 Modelling Capacity.10.2 Forms of Response for a Single-Capacity Circuit.10.2.1 The r-c Circuit.10.2.2 The r-c-r Circuit: Ramp Solution.10.2.3 The r-c-r Circuit: Periodic Solution.10.3 The Two-Capacity Wall.10.3.1 Wall Decay Times.10.3.2 Unit Flux Temperatures.10.3.3 The Orthogonality Theorem and the Transient Solution.10.3.4 Step and Steady-Slope Solutions.10.3.5 Ramp Solution.10.3.6 Examples.10.4 Finite Difference Method.10.4.1 Subdivision of the Wall.10.4.2 Computational Formulae.10.4.3 Discussion.10.4.4 Evaluation of Complex Quantities.10.5 The Electrical Analogue.10.6 Time-Varying Elements.10.7 Appendix.11 Wall Conduction Transfer Coefficients for a Discretised System.11.1 The Response Factors PHI50,k.11.2 The d Coefficients.11.3 The Transfer Coefficients b50,k.11.4 The Response Factors PHI00,k, PHI55,k and Transfer Coefficients a, c.11.5 Simple Cases.11.6 Heat Stored in the Steady State.11.7 Discussion.11.8 Appendix.12 The Fourier Continuity Equation in One Dimension.12.1 Progressive Solutions.12.2 Space/Time-Independent Solutions.12.2.1 The Transient Solution.12.2.2 The Periodic Solution.12.3 The Source Solution and its Family.12.3.1 Further Source-Based Solutions.12.4 Solutions for the Temperature Profile and Taylor's Series.12.5 Transform Methods.12.6 Use of the Solutions.12.7 Appendix: Penetration of a Signal into an Infinite Slab.13 Analytical Transient Models for Step Excitation.13.1 Slab without Films.13.1.1 Cooling at the Surface.13.1.2 Cooling at the Midplane.13.2 The Film and Slab, Adiabatic at Rear: Groeber's Model.13.2.1 Solution.13.2.2 Limiting Forms.13.2.3 Early and Late Stages of Cooling at the Surface.13.2.4 Cooling Curves: Exposed Surface.13.2.5 Surface Response Time.13.2.6 Cooling at the Midplane.13.2.7 Discussion.13.3 Jaeger's Model.13.4 Pratt's Model.13.5 A One-Dimensional System cannot have Two Equal Decay Times.13.6 Discussion.14 Simple Models for Room Response.14.1 Wall Time Constant Models.14.2 Enclosure Response Time Models.14.2.1 Response Time by Analysis.14.2.2 Response Time by Computation.14.2.3 Response Time by Observation.14.2.4 Response Time and HVAC Time Delays.14.3 Models with Few Capacities.14.3.1 One-Capacity Wall Models.14.3.2 One-Capacity Enclosure Models.14.3.3 Enclosure Models with Two or More Capacities.14.4 Discussion.15 Wall Parameters for Periodic Excitation.15.1 The Finite-Thickness Slab.15.2 The Slab with Films.15.3 Thermal Parameters for an External Multilayer Wall.15.4 Admittance of an Internal Wall.15.5 Discussion.15.6 An Exact Circuit Model for a Wall.15.7 Optimal Three-Capacity Modelling of a Slab.15.8 Appendix: Complex Quantities and Vector Representation.16 Frequency-Domain Models for Room Response.16.1 Basic Principles.16.2 24Hour Periodicity: Admittance Model.16.3 Submultiples of 24Hours.16.4 Further Developments.16.5 Periodic Response for a Floor Slab.17 Wall Conduction Transfer Coefficients for a Layered System.17.1 The Single Slab.17.2 Slope Response for a Multilayer Wall.17.3 Transient Solution for a Multilayer Wall.17.4 The Orthogonality Theorem.17.5 Heat Flows in a Multilayer Wall.17.5.1 Same-Side and Cross Excitation.17.5.2 Transfer Coefficients.17.6 Response Factors and Transfer Coefficients for an Example Wall.17.6.1 Two-Layer Wall.17.6.2 Wall with Resistances.17.6.3 Discussion.17.7 Derivations from Transfer Coefficients.17.7.1 Wall Thermal Capacity.17.7.2 Transfer Coefficients and Measures for Daily Sinusoidal Excitation.17.7.3 Transfer Coefficients, Decay Times and Time of Peak Flow.17.7.4 Transfer Coefficients with and without Film Coefficients.17.7.5 Summary of Modelling Parameters.17.8 The Equivalent Discretised Wall.17.8.1 Error and Wall Thickness.17.8.2 The Two-Capacity Homogeneous Wall.17.8.3 The Real Wall is Discretised.17.8.4 The Homogeneous Wall.17.8.5 Wall Modelling.17.9 Time- and Frequency-Domain Methods Compared.17.10 Appendix: Finding the Decay Times.17.11 Appendix: Inclusion of Moisture Movement.18 Accuracy of Temperature Estimates Using Transfer Coefficients.18.1 The r-c Model.18.2 The Single Slab Driven by a Ramp.18.3 The Single Slab Driven by a Flux.18.4 The Single Slab Driven Sinusoidally.18.5 Film and Slab Driven by a Ramp.18.5.1 Film and Slab as Separate Entities.18.5.2 Film and Slab as a Combined Entity.18.6 The General Wall.18.7 Discussion.19 Room Thermal Response Using Transfer Coefficients.19.1 Simplifying Assumptions.19.2 A Basic Enclosure.19.3 An Example Enclosure.19.3.1 Internal Heat Transfer.19.3.2 Heat Flow through the Walls.19.3.3 Thermal Response to Ambient Temperature and Heat Input.19.3.4 The Continuity Equations.19.3.5 Response of the Enclosure.19.3.6 Heating or Cooling when Comfort Temperature is Specified.19.4 Development of the Model.19.5 Infiltration between Adjacent Rooms.19.6 Discussion.19.7 Closure.Principal Notation.References.Bibliography.Index.

Modular mounting arrangement and method for light emitting diodes

Abstract: A modular light emitting diode (LED) mounting configuration is provided including a light source module having a plurality of pre-packaged LEDs arranged in a serial array. The module includes a heat conductive body portion adapted to conduct heat generated by the LEDs to an adjacent heat sink. A heat conductive adhesive tape connects the LED module to the mount surface. As a result, the LEDs are able to be operated with a higher current than normally allowed. Thus, brightness and performance of the LEDs is increased without decreasing the life expectancy of the LEDs. A plurality of such LED modules can be pre-wired together in a substantially continuous fashion and provided in a dispenser, such as a roll or box. Thus, to install a plurality of such LED modules, a worker simply pulls modules from the dispenser as needed, secures the appropriate number of modules in place, and connects the assembled modules to a power source.

Toroidal low-field reactive gas and plasma source having a dielectric vacuum vessel

Abstract: Plasma ignition and cooling apparatus and methods for plasma systems are described. An apparatus can include a vessel and at least one ignition electrode adjacent to the vessel. A total length of a dimension of the at least one ignition electrode is greater than 10% of a length of the vessel's channel. The apparatus can include a dielectric toroidal vessel, a heat sink having multiple segments urged toward the vessel by a spring-loaded mechanism, and a thermal interface between the vessel and the heat sink. A method can include providing a gas having a flow rate and a pressure and directing a portion of the flow rate of the gas into a vessel channel. The gas is ignited in the channel while the remaining portion of the flow rate is directed away from the channel.

Light enhanced and heat dissipating bulb

Abstract: A bulb comprises a seat; a plurality of metal heat sink each having two fixing surfaces, one fixing surface being fixed with an light emitting chip; and one end of each metal heat sink being placed into an insulated frame and then being fixed to a supporting surface of a heat conductive base; the metal heat sinks having an effect of absorbing heat energy and then transferring heat to the seat so as to dissipate heat; the metal heat sinks being integrally formed with the bulb base and then being combined to the seat; the heat conductive base having an inclined surface which is advantageous to reflect light from a light emitting diode so as to increase the illumination of the light emitting chip; and a metal adhesive layer being assembled to the supporting surface of the heat conductive base and the fixing surfaces of the metal heat sinks.

Nano-composite materials for thermal management applications

Abstract: Nano-composite materials with enhanced thermal performance that can be used for thermal management in a wide range of applications, including heat sinks, device packaging, semiconductor device layers, printed circuit boards and other components of electronic, optical and/or mechanical systems. One type of nano-composite material has a base material and nanostructures (e.g., nanotubes) dispersed in the base material. Another type of nano-composite material has layers of a base material with nanotube films disposed thereon.

Computer component protection

Abstract: A computing device is disclosed. The computing device includes a shock mount assembly that is configured to provide impact absorption to sensitive components such as a display and an optical disk drive. The computing device also includes an enclosureless optical disk drive that is housed by an enclosure and other structures of the computing device. The computing device further includes a heat transfer system that removes heat from a heat producing element of the computing device. The heat transfer system is configured to thermally couple the heat producing element to a structural member of the computing device so as to sink heat through the structural member, which generally has a large surface area for dissipating the heat.

Microchannel heat sinks: an overview of the state-of-the-art

Abstract: Computers are rapidly becoming faster and more versatile, and as a result, high-powered integrated circuits have been produced in order to meet this need. However, these high-speed circuits are expected to generate heat fluxes that exceed the circuit's allowable operating temperature, and so an innovative cooling device is needed to solve this problem. Microchannel heat sinks were introduced in the early 1980s to be used as a means of cooling integrated circuits. Since then, many studies have been conducted in the field of these microchannel heat sinks. Earlier research used mainly single-phase coolants in their heat sinks, but two-phase coolants are now the focus of more recent research. The purpose of this article is to present a state-of-the art literature review of the progress of research in the field of microchannel heat sinks. This literature will focus mainly on the most recent research, starting with the latter half of the 1990s.

Experimental study of a pulsating heat pipe using fc-72, ethanol, and water as working fluids

Abstract: Experimental studies were performed on a pulsating heat pipe (PHP), consisting of a heating section, an adiabatic section, and a condensation section incorporating a heat sink. The capillary tube used in this study has an inside diameter of 1.18 mm and a wall thickness of 0.41 mm. The experiments were conducted under the condition of pure natural convection, for heating powers from 5 to 60 W, fill ratios from 60% to 90%. Three working fluids—FC-72, ethanol, and deionized water—were used. The thermal oscillation of the thin wall surface was recorded by a high-speed data acquisition system. Such thermal oscillation waves are random for some run cases due to the randomly distributed vapor plug and liquid slugs inside the PHP. The thermal oscillation amplitude is much smaller for FC-72, due to its lower surface tension, than for ethanol and water, while the oscillation cycle period for FC-72 is shorter than for the other two fluids, indicating the faster oscillation movement in the channels, possibly due to t...

Cooling of electronics by electrically conducting fluids

Abstract: Apparatus to provide effective removal of heat from a high power density device. The apparatus has a heat spreader and a heat sink structure. The heat spreader is divided into one or more chambers. Electromagnetic pumps are placed inside each chamber in a configuration that facilitates easy circulation of liquid metal inside the chamber. The liquid metal preferably is an alloy of gallium and indium that has high electrical conductivity and high thermal conductivity. The liquid metal carries heat from a localized area (over the high power density device) and distributes it over the entire spreader. This results in a uniform distribution of heat on the base of the heat sink structure and hence effective removal of heat by the heat sink structure.

Semiconductor package with heat dissipating structure

Abstract: A semiconductor package with a heat dissipating structure includes a substrate, a chip and a heat dissipating structure. The chip is mounted on and electrically connected to the substrate. The heat dissipating structure includes a first heat sink having at least one positioning portion, and at least one second heat sink having at least one second positioning portion and at least one hollow portion. The second heat sink is mounted on the substrate, and the first positioning portion of the first heat sink is attached to the second positioning portion of the second heat sink, allowing the chip to be accommodated in a space defined by the first heat sink, the hollow portion of the second heat sink and the substrate. This semiconductor package has good heat dissipating efficiency and is cost-effective to fabricate.

Light insertion and dispersion system

Abstract: A light source injects light into a translucent light guide, particularly using high-power LEDs. A core to the light guide contains a homogenous mixture of fluid and a light dispersing agent to effect scattering. Scattered light passes though the light guide and may be used for illumination. A high power LED is provided with a reflector and heat sink to disperse waste heat, increasing the efficiency and life of the LED.