scispace - formally typeset
Search or ask a question

Showing papers on "Heat pipe published in 1997"


Patent
Hong Xie1
05 May 1997
TL;DR: In this article, a semiconductor device is thermally coupled to the bottom external surface of a cover, which includes an external top surface, an external bottom surface and an inner cavity that comprises a heat pipe.
Abstract: An apparatus for spreading the heat generated by a semiconductor device. In one embodiment, a semiconductor device, such as a CPU, is mounted to a package substrate. A cover is attached to the package substrate creating a space therebetween for accommodating the semiconductor device. The package cover includes an external top surface and an external bottom surface and an inner cavity that comprises a heat pipe. The semiconductor device is thermally coupled to the bottom external surface of the cover.

158 citations


Patent
11 Jul 1997
TL;DR: In this paper, a system for conditioning the air within an enclosure which houses heat producing equipment is described, which includes a passive heat removal system (12), for precooling the air, and a thermoelectric temperature control system (14) used in conjunction with the passive heat removing system to achieve additional cooling, temperature control and heating.
Abstract: A system for conditioning the air within an enclosure which houses heat producing equipment. The system includes a passive heat removal system (12), for precooling the air, and a thermoelectric temperature control system (14) used in conjunction with the passive heat removal system (12) to achieve additional cooling, temperature control and heating. The passive heat removal system (12) includes a heat pipe system. A power control system (30) includes a programmable control means (56) which receives signals, from a temperature sensor (36), which are indicative of the temperature of the air in the enclosure (20). Based upon these signals, the power control system (30) controls the activation of thermoelectric devices in the thermoelectric temperature control system (14) and controls the activation of fans (38, 42) to remove a desired amount of heat from the air in the enclosure (20) and discharge the unwanted heat to the outside air. A switching device (58) operates to apply battery power (60) to the power control system (30) if the electrical power source for the thermoelectric temperature control system (14) fails. A polarity reversal circuit (50) reverses the DC polarity of the DC voltage applied to the thermoelectric devices to reverse the heat pumping of the thermoelectric devices in the situation where the air in the enclosure (20) needs to be heated. Circuitry and sensors are provided to monitor the speed of the fans to detect any failure of a fan. A current control circuit supplies power to and temperature control of thermoelectric cooling devices.

139 citations


Patent
03 Jun 1997
TL;DR: In this article, a heat pipe containing heat transfer liquid is used to transfer heat from a pipe to a rotor with fixed magnets on the rotor blades, and a magnetic field is generated by a magnetic coil assembly that surrounds the heat pipe.
Abstract: A heat transfer apparatus is disclosed The heat transfer apparatus includes a heat pipe containing heat transfer liquid Disposed in the heat pipe is a centrifugal rotor assembly having fixed magnets on the rotor blades A magnetic field is generated by a magnetic coil assembly that surrounds the heat pipe The rotor assembly rotates in response to the magnetic field, agitating the heat transfer liquid A second embodiment is a liquid heat transfer system that includes a heat absorption chamber, a pump, and a heat exchanger where circulation and cooling of the heat transfer liquid occurs outside of the heat absorption chamber

115 citations


Patent
03 Oct 1997
TL;DR: In this paper, an internal, multiple-chamber evaporator for cooling a turbine engine stator vane is described, with the leading edge, middle, and trailing edge chambers defined by structural support ribs.
Abstract: The apparatus is a heat pipe with an internal, multiple chamber evaporator for cooling a turbine engine stator vane. The evaporator comprises leading edge, middle, and trailing edge chambers within the stator vane, with the chambers defined by structural support ribs. Each chamber is constructed with a continuous fine pore metal powder wick coating the internal surfaces of the chamber and enclosing the chamber's central vapor space, except the wick at the very trailing edge of the vane is formed by screen embedded in the adjacent powder wick. The evaporator chambers have capillary arteries which extend through the adiabatic section of the heat pipe and terminate in a condenser wick within a heat sink structure exposed to cooler air. A capillary artery also interconnects the wick of the trailing edge chamber to the wick of the middle chamber.

114 citations


Journal ArticleDOI
TL;DR: In this article, two flat copper-water axially grooved miniature heat pipes are fabricated employing the electric-discharge-machining (EDM) wire-cutting method.
Abstract: Two flat copper-water axially grooved miniature heat pipes are fabricated employing the electric-discharge-machining (EDM) wire-cutting method. Because of the advantage of the EDM method, axial grooves are provided around the entire interior perimeters of the miniature heat pipes. The two miniature heat pipes are tested under different heat inputs, cooling temperatures, and orientations. The maximum heat transfer rate for the heat pipes tested is about 40 W, and the maximum heat flux achieved is about 20 W/cm 2 , based on the outer surface of the evaporator. The effective thermal conductance of the heat pipe is on the order of 40 times that of copper based on the external cross-sectional area of the miniature heat pipe. If the effective thermal conductance is evaluated based on the interior cross-sectional area of the heat pipe, it can be 100 times higher than the thermal conductivity of copper. Analyses for heat-pipe limitations are also performed based on certain analytical relations. It is found that the capillary limit is the dominant heat transfer limitation for the miniature heat pipes tested in this paper. To improve the accuracy of the analytical model, the hydraulic radius in the capillary limit is corrected using the exact two-dimensional solutions found in the literature, and the expression for the friction factor that takes into account the shear stress at the liquid/vapor interface is adopted. The analytical results based on these modifications are compared with corresponding experimental results with good agreement.

103 citations


Patent
Ram S. Viswanath1
30 Dec 1997
TL;DR: In this paper, an apparatus and method for controlling the temperature of a heat generating device is described. Butler et al. present a pickup chuck with a heat pipe, which includes a first end defining an evaporator portion and a second end defining a condenser portion.
Abstract: An apparatus and method for controlling the temperature of a heat generating device. In one embodiment, a pickup chuck having a heat pipe is provided. The heat pipe includes a first end defining an evaporator portion and a second end defining a condenser portion. A thermally conductive member at the first end of the heat pipe is adapted to engage a surface of the heat generating device. Heat is transferred away from the heat generating device by engaging the thermally conductive member with a surface of the heat generating device.

85 citations


Patent
15 Dec 1997
TL;DR: In this article, a heat pipe has an embedded wick structure that maximizes capillary pumping capability, where the condensate collects in the wick and returns the fluid to high heat areas.
Abstract: A heat pipe has an embedded wick structure that maximizes capillary pumping capability. Heat from attached devices such as integrated circuits evaporates working fluid in the heat pipe. The vapor cools and condenses on a heat dissipation surface. The condensate collects in the wick structure, where capillary pumping returns the fluid to high heat areas.

73 citations


Journal ArticleDOI
TL;DR: In this paper, a numerical analysis of an adsorptive heat pump system with thermal wave heat regeneration is presented, using a two-dimensional model taking into account axial heat transfer in the circulating fluid and radial heat conduction in the adsorbent bed.

73 citations


Patent
09 Jun 1997
TL;DR: In this article, a vehicle steering wheel was modified from extremes to acceptable values by a heat pump with heat transfer occurring along heat pipe sections between primary heat exchangers at the gripped regions and a temperature modifiable surface.
Abstract: A vehicle steering wheel (12) has the temperature of its normally gripped regions (16, 18) modified from extremes to acceptable values by a heat pump (20) with heat transfer occurring along heat pipe sections (22, 24) between primary heat exchangers (26, 28) at the gripped regions (16,18) and a temperature modifiable surface (33). Circuit apparatus (67) automatically energizes the heat pump (20) to provide heating or cooling, as needed.

71 citations


Journal ArticleDOI
TL;DR: In this paper, the authors investigated the enhancement of the heat transport capacity of a monogroove heat pipe with electrohydrodynamic (EHD) pumping, where the EHD pump was located on the liquid channel in the adiabatic section of a heat pipe.
Abstract: The enhancement of the heat transport capacity of a monogroove heat pipe with electrohydrodynamic (EHD) pumping was investigated. The EHD pump was located on the liquid channel in the adiabatic section of the heat pipe. The heat pipe e uid used in all experiments was R-123, a new alternative refrigerant. The two experimental goals were to determine the magnitude of heat transport enhancement that could be achieved using the EHD pump and to demonstrate the controllability and recovery of the heat pipe during dryout. Both were successfully accomplished. Over 100% enhancement in the transport capacity was achieved using the EHD pump operating at 20 kV. This enhancement could be maintained with less than 0.08 W of electric power to the EHD pump. The EHD pump was also able to provide immediate recovery from dryout when the heat pipe had been experiencing progressive evaporator dryout for over 70 min at 400 W.

66 citations


Patent
12 Aug 1997
TL;DR: In this paper, a flexible member or tube fabricated from thermally conductive carbon fibers for transferring heat from a first portion, such as a base section of a portable computer, to a second portion such as the display section, where the sections of the computer move between open operating position and closed position.
Abstract: A computer includes a flexible member or tube fabricated from thermally conductive carbon fibers for transferring heat from a first portion, such as a base section of a portable computer, to a second portion, such as the display section of a portable computer, where the sections of the computer move between an open operating position and a closed position. The flexible member, fabricated from conductive fibers, is positioned so as to experience torsion upon opening the portable computer. A first heat pipe is thermally connected with a microprocessor in the base section at one end and at the other end is coaxially attached within the member or tube. A second heat pipe is similarly coaxially attached to the other end of the member or tube. The other end of the second heat pipe is positioned within the display section between the LCD screen and the back surface of the portable computer with an aluminum center tab attached to the second heat pipe for dissipating heat from the microprocessor to the back surface of the display section of the portable computer. Advantageously, a method for transferring heat between movable portions of a computer is disclosed.

Patent
16 Jul 1997
TL;DR: In this article, the authors present a system for temperature control of an electronic component including a heat plate supporting the component, a heat sensor, and a fan capable of providing air for cooling the heat plate.
Abstract: A system for temperature control of an electronic component includes a heat plate supporting the component; a heat plate temperature sensor; a fan capable of providing air for cooling the heat plate; and a fan control for using the heat plate temperature to control the operation of the fan to provide a substantially constant heat plate temperature. The system can further include a heat pipe assembly having fins and coupled to the heat plate with the fan capable of providing air to the fins. The heat pipe assembly can include at least two heat pipes each having first ends coupled to the heat plate and second ends situated in a condensation section where at least one of the heat pipes has a different working fluid than an other. A switch temperature or load current sensor can be coupled to the heat plate and supply data to a switch controller for receiving the switch temperature, determining whether the temperature or load current has changed, and adjusting a switching frequency of the at least one electronic switch device in response to any change of the switch temperature. A bus layer can be situated adjacent the component and selectively coated with an insulating material and studs can mechanically and electrically coupling the bus layer and a printed circuit board to the component. An insulating shield can be situated between the bus layer and the printed circuit board with the studs.

Patent
14 Aug 1997
TL;DR: In this article, a cooling system for cryogenic power conversion electronics is described, which can also include input/output means for supplying power to the power conversion apparatus and receiving power from the power converter.
Abstract: Methods and apparatus for cooling systems for cryogenic power conversion electronics are provided. The invention includes systems having electronic power conversion apparatus comprising at least one cryogenically operated semiconductor switch and at least one cryogenically operated capacitor and cooling means for cryogenically cooling the at least one cryogenically operated semiconductor switch and the at least one cryogenically operated capacitor to a temperature between 90K to 236K. The systems can also include input/output means for supplying power to said power conversion apparatus and receiving power from said power conversion apparatus. In alternative embodiments, liquid cryogens can be used in heat exchange systems in conjunction with refrigeration cold heads or heat pipes. In these embodiments, the cryogen can be recondensed if boiled.

Patent
06 Aug 1997
TL;DR: In this paper, the power dissipation of portable personal computers (PCs) is increased by conducting heat through a heat pipe arranged in a hinge structure interconnecting a display panel with a bottom keyboard housing, and conducting the heat into an area at the rear of the display panel.
Abstract: An arrangement and method for enhancing the cooling capacity of portable personal computers. The power dissipation of portable personal computers (PCs) is increased by conducting heat through a heat pipe arranged in a hinge structure interconnecting a display panel with a bottom keyboard housing, and conducting the heat into an area at the rear of the display panel.

Patent
Lawrence Shungwei Mok1
30 Jul 1997
TL;DR: In this article, an arrangement and method for increasing the cooling capacity of laptop computers through the utilization of a double-shelled rotational heat conduction apparatus which dissipates heat to the rear side of a liquid-crystal display of the laptop computer is presented.
Abstract: An arrangement and method for enhancing the cooling capacity of portable personal computers. More particularly, disclosed is an arrangement and method for increasing the cooling capacity of laptop computers through the utilization of a double-shelled rotational heat conduction apparatus which dissipates heat to the rear side of a liquid-crystal display of the laptop computer.

Patent
31 Dec 1997
TL;DR: In this article, a passive cooling system for cooling an enclosure containing electronic components is presented, where a hollowed portion of the enclosure is formed as an integral heat pipe containing a working fluid and a wick is provided for returning the working fluid to the evaporator by capillary action.
Abstract: A passive cooling system for cooling an enclosure containing electronic components. A hollowed portion of the enclosure is formed as an integral heat pipe containing a working fluid. The hollowed portion has an evaporator section located at the top and a condenser section located at the bottom. The enclosure also has hollowed side walls which serve as passage ways for the working fluid to flow through in between the evaporator and condenser sections. Gravity and the pressure of evaporation force the working fluid down to the condenser section. A wick is provided for returning the working fluid to the evaporator section by capillary action. Additionally, an ultrasonic transducer driven by the heat rejected from the condenser section may be used to help return the working fluid to the evaporator section. Finally, a check valve may be employed before the evaporator section for the working fluid to flow through.

Journal ArticleDOI
TL;DR: In this paper, the porosity and pore size distribution of rectangular porosimetric wicks for flat plate heat pipes were characterized using the techniques of mercury intrusion porosaimetry and scanning electron microscopy (SEM).
Abstract: Rectangular porous wicks for use in flat plate heat pipes were fabricated using copper powder (63 µm) sintered at 800°C and 1000°C. These wicks were characterized in terms of their porosity and pore size distribution using the techniques of mercury intrusion porosimetry and scanning electron microscopy (SEM). A uni-modal pore size distribution was obtained with most pores having sizes in the 30–40 µm range. Comparison was also made with cylindrical wicks fabricated by injection molding technique with the same binder and sintered at the same temperatures. Calculated permeability values of the rectangular wicks are comparable with commercially produced cylindrical wicks. When compared with conventional heat pipe wicks such as those using wire mesh, the advantage of these sintered wicks appears to be the existence of smaller pores and the controllability of porosity and pore size to optimize heat pipe performance.

Journal ArticleDOI
TL;DR: In this article, an experimental test facility was constructed to test and verify the operation of two parallel arrays of anisotropic micromachined (etched) micro heal pipes (MHPs) on a single crystalline (100) semiconductor silicon wafer.
Abstract: An experimental test facility was constructed to test and verify the operation of two parallel arrays of anisotropicalfy micromachined (etched) micro heal pipes (MHPs) on a single crystalline (100) semiconductor silicon wafer, A micro heat pipe is a small-scale device used to transport energy from a heat source to a heat sink in nearly isothermal operation. The individual MHP was an isosceles triangle with a length of 25.4 mm, and a width of 100 /xm and 260 fim for the arrays. A 7740 Pyrtx glass wafer was used to seal the pipe array hermetically. The transparent glass allowed visual inspection of the level of the working fluid filling the pipe array. Two working fluids were tested, pure water and methanol. A Kapton heater was used to supply the heat input, and cooling water flowing through the condenser (to remove the applied heat) was used as a heat sink. Filling charges of 5%, 10%, 20%, 30%, 50%, and 80% were tested. The axial temperature drop along the length of the pipe was measured using K-type therm...

Patent
23 Apr 1997
TL;DR: In this article, an integrated circuit heat sink contains a groove with extension tabs protruding above edges of the groove so that the tabs can be bent over to hold the heat pipe in the groove.
Abstract: An apparatus is a heat conducting connection between a heat pipe and a structure such as an integrated circuit heat sink. The heat sink contains a groove with extension tabs protruding above edges of the groove so that the tabs can be bent over to hold the heat pipe in the groove which is dimensioned to give a clearance space around the heat pipe. When the tabs are bent down far enough to deform the heat pipe or a heat conductive hardening material is used to fill the clearance space, the heat pipe is fixed in place. If the tabs are bent down to barely contact the heat pipe and a heat conductive non-hardening material is used to fill the clearance space, the heat pipe can still be rotated within the groove.

Journal ArticleDOI
TL;DR: In this paper, an experimental study of heat transfer from an array of copper plate fins supported by a copper heat pipe and cooled by forced air flow is presented, where the primary variable is the height of the fin stack, while the fin pitch, air flow rate, surface area and fin shape are fixed.

Patent
08 Sep 1997
TL;DR: In this article, electrostatic fields are used to induce heat pumping action of a working fluid and a plurality of heat pipes with no moving parts are used, which is conducive to devices of a wide range of scales.
Abstract: In the method of the present invention, electrostatic fields (20) are used to induce heat pumping action of a working fluid (18). A plurality of heat pipes with no moving parts are used. The operation of one pump enhances the operation of the next. The method of the present invention is conducive to devices of a wide range of scales. Furthermore, operation at partial power levels is practicable, and precise control of temperature possible. Control is further enhanced by the addition or removal of further units to the system. Reliability should be enhanced, and peak power demands reduced. Wide selection of possible working fluids (18) allows for the elimination of environmentally harmful halocarbons. In one embodiment of the present invention, chemical working fluids are eliminated entirely. In another embodiment, supercooled fluids such as liquid helium may be used while eliminating the wastage commonly encountered using such fluids.

Patent
12 Nov 1997
TL;DR: A heat pipe heat exchanger for regulating the temperature of a well-stream fluid conveyed in a subsea pipeline from a wellhead has an annular reservoir surrounding a section of pipeline adjacent the wellhead as mentioned in this paper.
Abstract: A heat pipe heat exchanger for regulating the temperature of a wellstream fluid conveyed in a subsea pipeline from a wellhead has an annular reservoir surrounding a section of pipeline adjacent the wellhead. One or more heat pipes extend from the annular reservoir into the seawater. In a heat removal configuration, a working fluid is contained within the annular reservoir. The working fluid boils and is evaporated by heat from the wellstream fluid and forms a vapor, which rises upwardly into and is condensed within the heat pipes, releasing heat into the surrounding seawater. The recondensed working fluid flows back down into the reservoir to repeat the cycle. In a heat providing configuration, the working fluid is contained in the heat pipes, where it is boiled by heat transferred from the surrounding seawater. The resulting vapor rises upwardly into the annular reservoir and the heat is transferred to the cooler wellstream fluids. Other embodiments involve having the one or more heat pipes inserted through the pipeline wall.

Proceedings ArticleDOI
01 Aug 1997
TL;DR: In this article, a bidisperse wick material within the circumferential vapor passages was used to overcome the evaporator limit of loop heat pipes, which is of about 0.07 MW/sq m, in order to improve the efficiency by threefold to tenfold.
Abstract: Loop heat pipes (LHPs) can transport very large thermal power loads over long distances, through flexible, small diameter tubes against gravitational heads. In order to overcome the evaporator limit of LHPs, which is of about 0.07 MW/sq m, work was carried out to improve the efficiency by threefold to tenfold. The vapor passage geometry for the high heat flux conditions is shown. A bidisperse wick material within the circumferential vapor passages was used. Along with heat flux enhancement, several underlying issues were demonstrated, including the fabrication of bidisperse powder with controlled properties and the fabrication of a device geometry capable of replacing vapor passages with bidisperse powder.

Patent
30 Jul 1997
TL;DR: In this article, a heat sink assembly for the removal of heat from semiconductor and power converter modules is presented, which includes a heat transfer layer, a fin stack, and a series of heat pipes.
Abstract: The invention is a heat sink assembly for the removal of heat from semiconductor and power converter modules. The packaging design for semiconductor modules and power converter modules provides efficient heat removal and a tight Faraday Cage. There is a heat transfer layer sandwiched between a CPU module and a power converter module. The heat sink assembly includes a heat transfer layer, a fin stack, and a series of heat pipes. The heat transfer layer has a slot for passage of power cables and sense lines which connects both the CPU module and the power converter module, and the power converter module and the printed circuit board. The heat sink chamber also serves as a Faraday Cage and thus attenuates EMI from the semiconductor module, the power converter module, the power cables, and the sense lines.

Patent
09 Jan 1997
TL;DR: In this paper, the authors propose a cooling structure for laptop computers, in which the heat is transferred to a heat pipe in the cover of the case behind the display screen, and the heat pipe is interconnected with the external wall of the cover by a holding fixture which, preferably, is integrated into the cover wall during manufacture.
Abstract: The apparatus is a cooling structure for laptop computers, in which the heat is transferred to a heat pipe in the cover of the case behind the display screen. The heat pipe behind the screen is interconnected with the external wall of the cover by a holding fixture which, preferably, is integrated into the cover wall during manufacture. The cover is specially constructed with high thermal conductivity carbon fibers which are oriented to preferentially conduct heat from the heat pipe to the cover and to spread the heat over the entire external surface of the cover for dissipation into the environment.

Patent
05 Feb 1997
TL;DR: In this article, a heat transfer device (30) dissipates and removes heat energy from a heat source and delivers the heat energy to a heat sink, which includes a diamond substrate (32) for receiving energy from the heat source.
Abstract: Heat transfer device (30) dissipates and removes heat energy from a heat source and delivers the heat energy to a heat sink. Heat transfer device (30) includes diamond substrate (32) for receiving the heat energy from the heat source. Interconnect point (36) connects to diamond substrate (32). Fiber (34), such as a carbon fiber, connects at interconnect point (36) to receive the heat energy from diamond substrate (32) and conduct the heat energy to the heat sink.

Journal ArticleDOI
TL;DR: In this paper, two model-predictive controllers (MPCs), operating on different time and length scales, coupled through constraints, are introduced for the Czochralski crystallization process, where microscopic properties in the crystal, such as the distributions of oxygen, dopant, and dislocations, are controlled indirectly by the addition of constraints to their nonlinear programs.

Patent
Herman W. Chu, Rakesh Bhatia1
20 May 1997
TL;DR: In this article, the authors present a modular apparatus for cooling an integrated circuit chip in a compact computer, which consists of a heat collector assembly operatively connected to the chip, a heat exchange assembly and a heat pipe extending from the heat collector to the heat pipe.
Abstract: The invention consists of a modular apparatus for cooling an integrated circuit chip in a compact computer. The apparatus includes a heat collector assembly operatively connected to the chip, a heat exchange assembly and a heat pipe extending from the heat collector assembly to the heat exchange assembly. The heat exchange assembly includes a primary housing, a fan at one end of the housing, and a secondary housing at the opposite end of the primary housing. The secondary housing has a plurality of fins and the primary housing as a plenum chamber between the fins and the fan. The invention also comprises a high-performance notebook computer and cooling apparatus combination which includes a pivoted outer cover and a cooling system located along the pivoting axis of the outer cover.

Patent
20 Aug 1997
TL;DR: In this article, a self-contained liquid cooled heat sink system disposed in a computer has a plurality of socket portions through which a cooling liquid is pumped, and the use of the heat pipe modules permits rapid and easy pull-away electrical and cooling system disconnection for each processor board as well as providing for effective cooling of the processors without the necessity of forcing a flow of air across them.
Abstract: A self-contained liquid cooled heat sink system disposed in a computer has a plurality of socket portions through which a cooling liquid is pumped. Operating heat from a plurality of heat-generating computer components, representatively circuit board-mounted processor chips, is efficiently transferred to the heat sink system by heat pipe modules associated with the heat-generating components. Each module includes (1) an evaporator plate held in thermal contact with its associated component, (2) a condenser plate removably plugged into one of the sockets and in a heat transfer relationship therewith, and (3) a plurality of thermosyphoning type heat pipes interconnected between the evaporator and condenser plates. The use of the heat pipe modules permits rapid and easy pull-away electrical and cooling system disconnection for each processor board as well as providing for effective cooling of the processors without the necessity of forcing a flow of air across them.

Journal ArticleDOI
TL;DR: In this article, a solar cooling unit based on solid-vapour intermittent absorption system was designed and fabricated, which utilizes thermal energy supplied by heat pipe vacuum tube solar collectors through thermosyphonic flow of water.