Showing papers on "Heat pipe published in 1998"

Microscale energy transport

Abstract: Preface Contributors Part I Fundamentals 1.Microscale Energy Transport in Solids 2.Heat Transport in Dielectric Thin Films and at Solid-Solid Interfaces 3.Microscale Radiation Phenomena 4.Melting and Freezing Phenomena 5.Molecular Clusters 6.Interfacial Forces and Phase Change in Thin Liquid Films Part II.Applications 7.Thermal Phenomena in Semiconductor Devices and Interconnects 8.Micro Heat Pipes 9.Microscale Heat Transfer in Biological Systems at Low Temperatures 10.Silicon Micromachined Thermal Sensors and Actuators Index

Cooling device with heat pipe

Abstract: The invention provides a cooling device provided with a heat pipe, which is capable of effectively radiating heat from electronic equipment such as a small-sized computer. The cooling device with the heat pipe comprises a plate-like container made of heat transferring metal for containing a working fluid, and having a heat absorbing surface larger than that of the body to be cooled, a the heat transferring metal column, and a hollow portion in which the working fluid exists. An alternating embodiment of the cooling device with the heat pipe comprises a plate-like container made of heat transferring metal, a heat absorbing wall having a large heat absorbing surface, and a plurality of protrusion portions.

Quick charge battery with thermal management

Abstract: A quick charge battery with thermal management is described which includes a cooler preferably disposed at least partially within the battery to transfer thermal energy. The cooler may comprise a thermoelectric generator, a microcooler, a heat pipe or combinations of the above. The cooler is capable of cooling the battery and in some embodiments selectively heating the battery to a minimum temperature level. The cooler functions to cool the battery and thereby minimizes thermal build-up produced by rapid charging of the battery.

Large area, multi-device heat pipe for stacked MCM-based systems

Abstract: The invention is a computer module for scalably adding computing power and cooling capacity to a computer system. Computing power can be added by merely adding additional printed circuit cards to the computing module. Cooling capability is added by adding heat pipes to the computer module. The computing module for a computer includes a first heat pipe assembly. The first heat pipe assembly has an evaporator plate with an evaporator surface. The first heat pipe also has a condenser in fluid communication with the evaporator plate. The evaporator plate is positioned adjacent one side of a printed circuit board populated with at least one electronic component. The computing module may use a printed circuit board which has two sides populated with electronic components. When a printed circuit board having components on two sides is used, a second heat pipe having the same construction, namely an evaporator plate with an evaporator surface and a condenser in fluid communication with said evaporator plate, is positioned adjacent the other side of said printed circuit board so that the electronic components on the other side are positioned adjacent said evaporator surface of said second heat pipe. The evaporator plate of each heat pipe is connected to the condenser by a plurality of necked-down regions. This forms at least one window between the condenser and the evaporator plate of each heat pipe. When more than one heat pipe is used in the computing module, the windows of the various heat pipes align. Electrical connector components can be routed through the windows. The connector component connects the edge of the printed circuit board positioned near the windows. Additional building blocks, comprising one additional heat pipe and one additional populated printed circuit card can be added to further scale up or upgrade a computer system.

Two-phase constant-pressure closed-loop water cooling system for a heat producing device

Abstract: A cooling device for a machine, especially, but not limited to, a device for cooling the central processing unit (CPU) of a desktop computer, thereby increasing the speed at which it can operate. In the preferred embodiment, the cooling device includes a copper evaporation chamber and a conduit made of copper pipe having a condensation coil, which are connected in a single closed loop, and contain water. As heat is absorbed by the evaporation chamber from the CPU or other heat generating component, the water changes from liquid to gas, and gravity and pressure differences cause the water to circulate through the conduit. As heat is transferred from the conduit to its surroundings, the water changes from gas to liquid, and returns to the evaporation chamber. The high heat of vaporization and condensation of water allows heat to be efficiently transferred with a small difference in temperature between its liquid and gaseous states. The boiling point of the water is reduced by a partial vacuum inside the evaporation chamber and conduit, to reduce the temperature to which the CPU or other component can be efficiently cooled by the invention. Alternatively, other fluid having a high heat of vaporization and condensation may be substituted for water, and the other materials that are good conductors of heat may be substituted for copper in the evaporation chamber and conduit. The invention may be installed during manufacture, or it may be sold separately and installed later.

Flat plate heat pipe cooling system for electronic equipment enclosure

Abstract: A cooling system for an electronic equipment enclosure employs a flat plate heat pipe to deliver heat from the interior of the enclosure through a connector to a removable external heat sink. The heat pipe includes a metallic bottom plate having a depression therein containing a set of rods evenly spaced from one another. A top plate covers the bottom plate with the rods compressed therebetween. Channels formed between adjacent rods are partially evacuated and injected with an evaporative fluid. The fluid and its vapor circulate in the channels to convey heat from a warm end of the heat pipe to a cool end. The heat sink is of similar construction.

Docking station with auxiliary heat dissipation system for a docked portable computer

Abstract: A portable computer docking base has incorporated therein a plug-in cooling system used to provide auxiliary operating heat dissipation for a portable notebook computer moved through a docking path along the base into a docked relationship therewith. The docking base cooling system has a fan-cooled heat sink member disposed within its housing, with a thermal plug structure projecting outwardly from the heat sink into the docking path. As the computer reaches its docked orientation on the base, the thermal plug is received in a socket within a heat sink portion of the computer's internal cooling system. The mated plug and socket portions of the two cooling systems form a thermal link therebetween that permits computer operating heat to be transferred to the docking base heat sink for dissipation therefrom. In one embodiment thereof the thermal plug structure is partially defined by an outwardly projecting evaporating end portion of a thermosyphoning heat pipe. In another embodiment thereof, the outwardly projecting thermal plug structure is integrally formed with the internal docking base heat sink and comprises opposing metal plug sections separated by a resilient material. When the plug structure enters the computer heat sink socket, the plug sections are resiliently forced toward one another to provide a socket clamping force on the received plug structure and increase the socket-to-plug heat transfer efficiency.

Heat sink assembly with rotating heat pipe

Abstract: A portable computer includes a chassis having a heat producing electronic component mounted therein. A heat sink is mounted in the chassis adjacent the component. A heat pipe has a first end rotatably connected to the heat sink and extends to a second end engaged with the component. The heat pipe is rotatable so as to move the second end into and out of engagement with the component.

Electronic component cooling using a heat transfer buffering capability

Abstract: Heat transfer out of a housing for a locallized source of heat such as that produced by a semiconductor chip of electronic apparatus is provided by a low thermal impedance heat transfer member such as a heat pipe, a thermal reservoir or heat transfer buffering member and a Peltier effect device interfaced with the thermal reservoir and the ambient surrounding the housing so as to provide a refrigeration function for the thermal reservoir. A high heat capacity or high latent heat of phase transition material can be used for the thermal reservoir. In a portable computer with a battery power supply, the thermal reservoir can be independent or the battery can be employed in the thermal reservoir functions.

Semiconductor package lid with internal heat pipe

Abstract: The thermal resistance to lateral flow of heat flux through the lid of a semiconductor package may be reduced by incorporating one or more heat pipes into the lid itself. This has the further benefit of reducing the effective thermal resistance of the mechanical interface between the lid of the package and an external heat sink, owing to an increased area over which the heat flux is conducted. The result is a reduced temperature at the source of heat inside the semiconductor package.

Method of junction temperature determination and control utilizing heat flow

Abstract: A method and apparatus is provided for monitoring and controlling the temperature at the heat producing portion of an electrical current carrying device without direct measurement at the heat producing site. An integrated circuit 22 is thermally attached to a plurality of heat dissipating paths; top side heat conduction path 24, bottom side heat conduction path 26, and board level heat conduction path 28. On one of the heat conduction paths exists a heat flow sensor. This sensor is comprised of an inner thermistor 32 and an outer thermistor 34. The measured heat flow is combined with a single point temperature measurement and the thermal conductivity between the heat source and the temperature measurement point to produce the temperature at the heat source. This temperature is monitored in order to keep the temperature of the electrical current carrying device below critical levels or within a specified range.

Scalable and modular heat sink-heat pipe cooling system

Abstract: Modular heat sinks utilizing heat pipes to provide a more uniform temperature distribution over a packaged integrated circuit and efficient heat sinking in either free or forced convection environments. The heat sinks utilize both horizontal and vertical heat pipes to transfer heat both horizontally and vertically in the heat sinks. Selection of the number of heat pipes used allows tailoring of the heat sink capabilities for different applications using the same fundamental assemblage of parts. Various embodiments are disclosed.

Performance of a Heat Pipe Solar Collector

Abstract: This paper presents a comparative study between theoretical predictions and experimental results of a flat-plate solar collector with heat pipes. The theoretical model for the heat pipe solar collector is based upon the method by Duffie and Beckman (1980), modified to use heat pipes for energy transport. The methanol filled heat pipes are self-contained devices whose evaporators are inserted under pressure in the flat plate of the solar collector and the heat exchange is carried out at their condensers. The evaporators contain a wick of one mesh layer to ensure a better distribution of the working fluid. The condensers are wickless and inclined 15 deg more than the inclination of the evaporators to facilitate the return of the condensate to the evaporators. The time constant of the heat pipe solar collector was calculated and found to be about 23 minutes. Also presented in this paper are comparative experimental results of the proposed solar collector and a conventional commercial solar collector. The two collectors were tested simultaneously. The instantaneous efficiencies of the heat pipe solar collector are lower than the conventional collector in the morning and higher when the heat pipes reach their operating temperatures.

Thermocapillary Effects on the Stability of a Heated, Curved Meniscus

Abstract: An investigation of thermocapillary effects on heated menisci formed by volatile liquids in capillary pumped heat transfer devices has been conducted. This research was motivated by the importance of the evaporation process from porous or grooved media integral to the operation of capillary pumped heat transport devices such as heat pipes and capillary pumped loops. From analysis, a criteria was established which predicts the thermal conditions at which the destablizing influences of thermocapillary stresses near the contact line of a heated and evaporating meniscus cause the meniscus to become unstable. Experimentally, two different idealized models of capillary pumped phase change loops were investigated to assess the suitability of the predictions. Correspondence between theory and experiment was observed. Given the observed dry-out of the evaporator at higher heat inputs after the meniscus becomes unstable, the importance of predicting the conditions at the instability onset is made clear.

Method and apparatus for transferring heat generated by a battery

Abstract: An apparatus and method for controlling the temperature of a battery used in a spacecraft or an electric vehicle are disclosed. The apparatus includes a thermal conductor, such as a thermally-conductive heat pipe or forced-fluid cooling loop, that is in thermal contact with thermally-conductive cell terminals of the battery, and a heat sink, such as a radiator. The inventive method includes operating the battery to generate and conduct heat to the thermally-conductive battery cell terminals. The generated heat is passed via conduction from the terminals to the thermal conductor. The heat is conducted through the thermal conductor to a heat sink which may be remotely located with respect to the battery. Preferably, the thermal conductor remains electrically insulated from the battery cell terminals and the heat sink.

Heat dissipation system for a laptop computer using a heat pipe

Abstract: The present invention provides heat dissipation systems for use in hinged computing devices which includes a thermally conductive joint ( 36 ). The joint has first and second receptacles ( 104, 108 ) which are generally parallel to and adjacent one another. A first heat pipe ( 22 ) is at least partially disposed within the first receptacle and is adapted to be thermally coupled to a heat source within the hinged computing device. A second heat pipe ( 30 ) is at least partially disposed within the second receptacle and is adapted to be thermally coupled to a heat sink. The thermally conductive joint permits the transfer of heat from the first heat pipe to the second heat pipe to transfer heat from the heat source to the heat sink portion of the hinged computing device.

Thermo-siphon and manufacturing method of thermo-siphon and information processing apparatus

Abstract: The present invention aims to reduce as much as possible the weight of the thermo-siphon being used in spreading heat of the mobile information processing apparatus. The heat spreading board 5 and the thermo-siphon 6 is installed at the lid 51 of the notebook type personal computer, and the heat from the CPU 1 is conducted to the thermo-siphon 6 via the heat pipe 3. The heat spreading board 5 includes the thick part 33 and the thin part 34. The thin part 34 contributes in reducing the weight of the heat spreading board 5.

Electronic device having a plug-in unit with a heat sink structure

Abstract: A heat sink structure for an electronic device of the type having a chassis and a plug-in unit provides efficient heat dissipation for a heat-generating component on a printed circuit board within the unit. In a preferred embodiment, a first heat pipe is fixedly attached to a heat dissipating plate for the heat generating component. At the opposite end, the first heat pipe is held by a connector plug attached to the unit. At one end, a second heat pipe is held by a plug-receiving seat that is fixedly attached to a backboard of the chassis. At the opposite end, the second heat pipe is fixedly attached to a heat dissipating portion on the chassis. The first heat pipe, plug, plug-receiving seat and second heat pipe transfer heat from the heat-generating component to the heat-dissipating portion.

The use of heat pipes in personal computers

Abstract: With the continuing increase of CPU and system power dissipation requirements in personal computers, including notebooks, desktops, workstations and servers, the last three years have witnessed increasing use of and interest in heat pipes in personal computers to meet cooling requirements. The paper reviews heat pipe applications in notebook computers and high end systems. Heat pipe's main structure, components, and operation are briefly reviewed to give the readers the necessary background in heat pipes. In notebooks, heat pipe-to-keyboard thermal solutions have been the mainstream thermal solutions used in Pentium/sup R/ based notebooks and sub-notebooks, providing about 7 W of CPU cooling solutions. New technologies like the thermal hinge concept, RHE (remote heat exchanger) thermal solutions and roll-bond heat pipes are also reviewed. Testing data on RHE prototypes showed that the technology can provide thermal resistance of 3.66/spl deg/C/W from the CPU case to the outside ambient. In high performance systems, the conventional heat pipe heat sinks are reviewed first. The heat pipe lid/plate concept is then proposed and reviewed. The heat pipe lid is designed to be an extremely efficient heat spreader or plate and is being developed for high end cooling requirements. Testing data on early prototypes showed that they can achieve a level of 0.07/spl deg/C/W spreading resistance for a /spl sim/3"/spl times/5" size heat pipe lid. Finally, the paper summarizes the future outlook of heat pipes for cooling of personal computers.

The Minimum Meniscus Radius and Capillary Heat Transport Limit in Micro Heat Pipes

Abstract: Based on the momentum conservation and Laplace-Young equations, an analytical expression for the minimum meniscus radius was derived and an expression for the maximum capillary heat transport limit in micro/small heat pipes was obtained. These expressions incorporated the shear stresses at the liquid/solid and liquid/ vapor interfaces, contact angle effects, vapor pressure drop, tilt angle, groove dimensions, and channel angle effects. In order to verify the expressions derived herein, comparisons with experimental data from triangular grooves and micro heat pipes were made; they demonstrated that these equations can be used to predict the maximum capillary heat transport in the micro/small triangular grooves or micro heat pipes with a higher degree of accuracy, and they can explain the behavior better than previously developed models.

The Heat Transport Capacity of Micro Heat Pipes

Abstract: The original analytical model for predicting the maximum heat transport capacity in micro heat pipes, as developed by Cotter, has been re-evaluated in light of the currently available experimental data. As is the case for most models, the original model assumed a fixed evaporator region and while it yields trends that are consistent with the experimental results, it significantly overpredicts the maximum heat transport capacity, In an effort to provide a more accurate predictive tool, a semi-empirical correlation has been developed. This modified model incorporates the effects of the temporal intrusion of the evaporating region into the adiabatic section of the heat pipe, which occurs as the heat pipe approaches dryout conditions. In so doing, the current model provides a more realistic picture of the actual physical situation. In addition to incorporating these effects, Cotter's original expression for the liquid flow shape factor has been modified. These modifications are then incorporated into the original model and the results compared with the available experimental data. The results of this comparison indicate that the new semiempirical model significantly improves the correlation between the experimental and predicted results and more accurately represents the actual physical behavior of these devices.

Network-type heat pipe device

Abstract: A network-type heat pipe device is disclosed, wherein the network-type heat pipe device comprises a heat dissipating unit with a network shape, a heat absorbing unit of any desired shape, and two single flexible capillary pipes connecting the heat absorbing unit with the heat dissipating unit The working fluid filled in the heat pipe is of a predetermined quantity smaller than the internal volume of the heat pipe The inside diameters of the capillary pipes of the network-shaped heat dissipating unit and the connecting capillary pipes are small enough such that the vapor and liquid segments of the working fluid may distribute therein by capillary effect As the heat absorbing unit is heated, the mutual actions of the pushing or compression force generated due to the vaporization at the heat absorbing unit, the resisting force generated due to the vapor condensation at the heat dissipating unit, and the gravitational force generated due to the liquid segments in the vertical part of the capillary pipes in the heat dissipating unit and the connecting pipes cause a circulating flow for the working fluid to carry heat from the heat absorbing unit to the heat dissipating unit The heat absorbing unit can be placed under the heat dissipating unit so as to enhance the gravitational force for circulating the working fluid in the single direction in the flow passage and to increase the heat transport from the heat absorbing unit to the heat dissipating unit