Showing papers on "Heat pipe published in 2004"

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.

Cooling structure for disk storage device

Abstract: A disk drive box 10 accommodates a plurality of disk drives 20 within a case 11 . A side face of each of the drives 20 is provided with a heat-absorbing part 40 including a heat pipe, corresponding to heat producing area HP. The heat taken away by the heat-absorbing part 40 is transmitted to a heat sink 50 of the rear of a backboard 30 via a heat connector 60 . The heat sink 50 is cooled by cooling air flowing through an air duct 7 . By cooling the drive 20 with the heat pipe, clearances between the drives 20 can be substantially eliminated, and it is made unnecessary to form an opening for air cooling in the backboard 30 . Thus, size reduction is possible, and it is possible to increase the degree of freedom for a wiring pattern formed on the backboard 30.

Motor rotor cooling with rotation heat pipes

Abstract: A heat pipe is partially-filled with a liquid, such as water, and is used to transfer heat from a rotating element, such as a rotor, via phase change and internal recycle of the liquid. Several heat pipes may be disposed radially around the rotating axis of the rotating element. The heat pipes may have a curved inner surface with a curvature not corresponding to the central axis of the heat pipe and positioned opposite the rotating axis so to experience greater centrifugal forces, to advance formation of a liquid film to improve heat transfer. For a rotor, the heat pipes, though individually placed as revolving heat pipes, in total exhibit behavior that approximates the favorable heat-transfer behavior of a single larger rotating heat pipe, but with heat-transfer surface area dispersed throughout the rotor, and without compromising structural integrity of the rotor shaft.

Vapor chamber with sintered grooved wick

Abstract: A heat pipe heat spreader is provided having a substantially L-shaped enclosure with an internal surface and a plurality of post projecting from the surface. A working fluid is disposed within the enclosure, and a grooved wick is formed on at least a portion of the internal surface. The grooved wick includes a plurality of individual particles having an average diameter, and including at least two lands that are in fluid communication with one another through a particle layer disposed between the at least two lands that comprises less than about six average particle diameters. A method for making a grooved heat pipe wick on an inside surface of a heat pipe container a layer of sintered powder between adjacent grooves that comprises no more than about six average particle diameters.

Transport in Flat Heat Pipes at High Heat Fluxes From Multiple Discrete Sources

Abstract: A three-dimensional model has been developed to analyze the transient and steady-state performance of flat heat pipes subjected to heating with multiple discrete heat sources. Three-dimensional flow and energy equations are solved in the vapor and liquid regions, along with conduction in the wall. Saturated flow models are used for heat transfer and fluid flow through the wick. In the wick region, the analysis uses an equilibrium model for heat transfer and a Brinkman-Forchheimer extended Darcy model for fluid flow. Averaged properties weighted with the porosity are used for the wick analysis. The state equation is used in the vapor core to relate density change to the operating pressure. The density change due to pressurization of the vapor core is accounted for in the continuity equation. Vapor flow, temperature and hydrodynamic pressure fields are computed at each time step from coupled continuity/momentum and energy equations in the wick and vapor regions. The mass flow rate at the interface is obtained from the application of kinetic theory Predictions are made for the magnitude of heat flux at which dryout would occur in a flat heat pipe. The input heat flux and the spacing between the discrete heat sources are studied as parameters. The location in the heat pipe at which dryout is initiated is found to be different from that of the maximum temperature. The location where the maximum capillary pressure head is realized also changes during the transient. Axial conduction through the wall and wick are seen to play a significant role in determining the axial temperature variation.

Heat transfer mechanism, heat dissipation system, and communication apparatus

Abstract: A heat transfer mechanism for dissipating heat from a heat generating body to a heat dissipating part, realizing both a high elasticity and a high thermal conductivity, comprised of a film-shaped heat conductor for transferring heat to the heat dissipating part and an elastic member for imparting elasticity to the film-shaped heat conductor, the film-shaped heat conductor being formed from metal foil-type flexible heat pipes or carbon-based thermal conductive sheets.

Heat pipe fin stack with extruded base

Abstract: A heat sink has a base plate to be clamped against a heat source and one or more heat pipes containing a phase change fluid. Each heat pipe has an elongated tubular evaporator fitted in a channel in the base plate, and a columnar condenser part perpendicular to the base plate forming a structural column for air heat exchange fins. The channel in the base plate is parallel to an edge. An additional channel or ridge is provided, also parallel to the edge, for receiving a clamp or spring clip to urge the base plate against the heat source. The base plate is inexpensively extruded with the parallel channels, ridges, etc., extending across the width of the base plate parallel to the edge. The heat sink has a minimum number of inexpensive parts yet is highly thermally efficient.

Thermal solution for electronic devices

Abstract: A thermal solution for an electronic device, which is positioned between a heat source and an external surface of the electronic device and/or another component of the electronic device, where the thermal solution facilitates heat dissipation from the heat source while shielding the external surface and/or second component from the heat generated by the heat source.

Wick structure of heat pipe

Abstract: A composite wick structure of a heat pipe includes wick structure fabricated from a woven mesh and sintered powder. The woven mesh is attached to an internal sidewall of a tubular member, while the sintered powder is coated on at least one side of the internal sidewall. By the better capillary force provided by the sintered powder, the liquid-phase working fluid can reflow to the bottom of the heat pipe quickly to enhance the heat transmission efficiency. Further, the problems of poor capillary effect of the woven mesh and the problems caused by usage of an axial rod during the process of applying sintered powder can be resolved.

Apparatus including a thermal bus on a circuit board for cooling components on a daughter card releasably attached to the circuit board

Abstract: A daughter card includes a number of circuit modules generating heat and a spring member transmitting the heat to a thermal bus extending along a circuit board adjacent to one side or to each side of a connector to which the daughter card is releasably attached. One or more contact surfaces of the spring member releasably contact one or more mating surfaces of a thermal bus at a side of the connector or at both sides of the connector. A heat pipe may additionally be used to direct heat from the thermal bus to a heat absorber.

Light emitting apparatus

Abstract: The present invention provides a method and apparatus for using light emitting diodes for curing and various solid state lighting applications. The method includes a novel method for cooling the light emitting diodes and mounting the same on heat pipe in a manner which delivers ultra high power in UV, visible and IR regions. Furthermore, the unique LED packaging technology of the present invention utilizes heat pipes that perform very efficiently in very compact space. Much more closely spaced LEDs operating at higher power levels and brightness are possible because the thermal energy is transported in an axial direction down the heat pipe and away from the light-emitting direction rather than a radial direction in nearly the same plane as the “p-n” junction.

Effects of gravity on the performance of pulsating heat pipes

Abstract: Pulsating heat pipes made of a thin aluminium plate (250 × 60 × 2.2 mm) with small internal channels and charged with a refrigerant (R-114) have been tested under normal to high gravity (1‐2.5 g0) and reduced gravity ( ∼± ±0.02 g0 )l evels to investigate the effect of gravity on their heat transport characteristics. Reduced gravity experiments were performed aboard Falcon 20 aircraft flying parabolic trajectories, yielding about 20 s of reduced gravity at ∼± ±0.02 g0. Under normal and hypergravity conditions, both the orientation of the pulsating heat pipe and locations of the heated and cooled sections affected the heat transfer performance. For example, large temperature fluctuations were observed when the heat pipe was oriented vertically and heated at the top. Under reduced gravity, however, the heat pipes showed better operating and heat transport performance than that under normal and hypergravity. These experiments have, for the first time, confirmed that pulsating heat pipes are capable of operating satisfactorily under reduced gravity and, thus, that they should be suitable for deployment in space applications. A theoretical analysis revealed the possibility that this type of a heat pipe with larger channel diameters (up to 5 mm for R114 as a working fluid) could work under microgravity, though they may not work on the ground.

Two stage radiation thermoelectric cooling apparatus

Abstract: The present invention provides a thermoelectric cooling apparatus for cooling an electronic device such as a CPU, or a computer chip. The apparatus cools the electronic device by two stages. In the first stage, a heat absorbing block collects the heat produced by the electronic device and the apparatus pre-cools the electronic device by dissipating a portion of the collected heat in a distant location through a front heat conductive device and a front radiator. Thereby the heat of the electronic device is reduced to a degree that a TEC can efficiently handle. In the second stage, a TEC of the apparatus dissipate the residual of the heat produced by the electronic device through at least a back heat pipe and a back radiator.

System and apparatus for heat removal

Abstract: A system for removing heat from an encased electronic device. The system includes a thermal ground, conduction pathways thermally coupling heat-producing elements of the device to the thermal ground so that the thermal ground receives heat produced by the heat-producing elements, and a heat dissipation element thermally coupled to the thermal ground and configured to transfer heat from the thermal ground to an environment outside the device. The conduction pathways and heat dissipation element provide a capacity to remove heat from the encased electronic device such that heat removal by convection from the heat-producing elements is not required.

Heat dissipating device with heat pipe

Abstract: A heat dissipating device incorporating heat pipes is disclosed. The heat dissipating device includes a base, a plurality of heat-dissipating fins and at least one heat pipe. The heat pipe includes an evaporating portion attached to the base, a middle-portion and a condensing portion extending through the fins. Bottoms of the evaporating portion of the heat pipe and the base are coplanar, and the condensing portion extends opposite to the evaporating portion.

Heat transfer device and method of making same

Abstract: A capillary structure for a heat transfer device, such as a heat pipe is provided having a plurality of particles joined together by a brazing compound such that fillets of the brazing compound are formed between adjacent ones of the plurality of particles and one or more vapor vents are defined in the capillary structer. In this way, a network of capillary passageways are formed between the particles and vapor-vents through the capillary structure so as to aid in the transfer of working fluid by capillary action, while the plurality of fillets provide enhanced thermal transfer properties between the plurality of particles so as to greatly improve over all heat transfer efficiency of the device. A method of making the capillary structure according to the invention is also presented.

Memory heat sink

Abstract: An apparatus is provided for dissipating heat from a semiconductor device that meets dimensional requirements for the semiconductor device and provides enhanced cooling for the semiconductor device. The apparatus provides a relatively large surface area for transferring heat away from a semiconductor device, and provides for enhanced coolant flow through or around the apparatus. The apparatus includes a channel that may accommodate a heat pipe to further enhance transfer of heat away from the semiconductor device.