Showing papers on "Heat pipe published in 1971"

Environmental control unit

Abstract: The application discloses an improved environmental control unit using in unitary combination a heat pipe as the heat source for the regeneration of the L-wheel The heat pipe contains sodium metal which is vaporized by heating one end of the pipe in a firebox remote from the environmental control unit The other end of the heat pipe extends into the heating section just upstream from the L-wheel There, the air passing over the heat pipe surface, which optionally may be finned, causes sodium vapor in the pipe to condense, thus giving up its latent heat of condensation to the air stream, heating it to a temperature sufficient to dry the wheel The improved heat pipe is efficient, safe, easily controllable and self-adjustable

Heat pipe and method and apparatus for fabricating same

Abstract: A unit for recovering thermal energy which utilizes a plurality of unique heat pipes, and the method and apparatus for fabricating the heat pipes is disclosed. The heat pipes are disposed horizontally and are filled with a volume of working fluid sufficient to cause the liquid phase to travel in either direction by gravity. Circumferential capillary grooves in the side walls of the heat pipes transport the liquid phase vertically above the liquid level to increase the area of the liquid-vapor interface. Additionally, the solid metal strips which form the grooves provide a low impedance thermal path from the walls of the heat pipe to the liquid-vapor interface where evaporation and condensation occur. These two factors significantly increase the efficiency of the system. A divider plate having an X-shaped cross section separates the liquid phase from the high velocity vapor phase to prevent slugging under high energy transfer conditions. The divider plate is operative when the unit is disposed in either of two horizontal positions. The method and apparatus provides a means for fabricating a spiraled capillary groove by cutting the metal from the wall of the tube and raising and folding the cut metal over to provide a groove having a narrow opening for a maximum capillary action. The cutting tool has a curved cutting edge formed by the intersection of a planar surface and a cylindrical surface. Apparatus for driving the cutting tool is also described.

Heat Pipe Oven Applications. I. Isothermal Heater of Well Defined Temperature. II. Production of Metal Vapor‐Gas Mixtures

Abstract: A concentric heat pipe oven is described, which serves as an oven with a highly homogeneous temperature distribution as required by such applications as crystal growing, thermal treatment of materials, and radiation standards. The design is simpler than conventional ovens with similar temperature stability and homogeneity. The temperature control is replaced by a pressure control. This device is used in a modification of the heat pipe oven that generates homogeneous mixtures of a vapor (such as a metal vapor) and an inert gas at well defined total pressure, partial pressure, temperature, and optical path length. All the features of the previously described heat pipe oven are maintained with the additional option that allows quantitative total and partial pressure measurements without relying on vapor pressure curves.

Heat exchanger using u-tube heat pipes

Abstract: A heat exchanger of the tube and fin type in which either straight or U-shaped elongated heat pipes are employed as the tube members. The radiating fin members are arranged in parallel fashion in a direction transverse to the heat pipe members and are spaced in either a uniform or non-uniform manner. The heat pipes are filled with a working fluid and further may contain a porous sleeve whereby the liquid, upon boiling is driven to a first end of the tube, condensed and returned to the opposite end of the tube by capillary action so as to maintain a highly uniform temperature level along the length of the heat pipes. The porous return medium may be omitted where tubes are oriented with condensing section above evaporating section. The tube and fin structure is provided with an isolating barrier between at least two of the fins which are located intermediate the ends of the structure, which isolating barrier is then arranged substantially coplanar with a barrier wall separating the region of elevated temperature from a region of reduced temperature level. The isolating barrier may be formed of an insulating or conductive material. Blower means are preferably provided in each of the aforesaid regions for moving air contained within its specific region over the radiating fins. The heat pipe members transfer the heat from the region of elevated temperature level to the region of reduced temperature level in a highly efficient manner so as to yield a heat exchange member of high efficiency while eliminating the need for separate pump and fluid transport means normally employed in heat exchange units of equivalent cooling capacity. A heat exchange unit of the tube and plate type may be substituted for the aforementioned tube and fin type providing a unit of equivalent capacity and efficiency.

Permafrost structural support with heat pipe stabilization

Abstract: Structural support assembly for use in arctic and subarctic (permafrost) areas or in any areas where the upper ground layer is subject to a severe annual freeze-thaw cycle, including the cooperative combination of a support structure and a heat pipe element installed in generally frozen soil. The heat pipe is of a suitably complementary configuration and/or disposition with respect to the support structure to provide appropriate stabilization of the surrounding frozen soil. In one embodiment, the heat pipe element is disposed externally of the support structure and, in another embodiment, it is disposed internally of (and integrally combined with) such structure. The external embodiment further includes one version employing a linear (straight) heat pipe element and another version employing an angular (helical) element.

Heat transfer apparatus with improved heat transfer surface

Abstract: A heat transfer device, defined here as a heat link, having a capillary vaporizer adjacent a heat source, transfers heat to a heat sink by vaporization and condensation of a heat transfer fluid within the device. A first passage is provided for conveying vapor from the capillary vaporizer to the heat sink. Another passage which is essentially a continuation of the first passage, conveys condensed liquid from the heat sink to the vaporizer, thus allowing the distance that the liquid must flow through capillary material to be quite short. Contact of the returning liquid with the surface of the vaporizer is assured by providing means for maintaining the temperature of the liquid in the return line at a sufficiently low temperature that any vapor will condense; or, alternatively, by having means for extracting any vapor formed in the returning liquid. In this manner, the heat link operates with high heat flux without any substantial resistance to liquid flow through a long capillary flow path. By thus replacing almost all of the liquid return wick, with its high resistance to fluid flow, of heat pipes with a low flow resistance liquid passage or conduit, the heat flux capacity of the heat link is greatly increased over that of the heat pipe while the quantity of porous material used and the heat link weight are considerably reduced so that a heat link typically has 10 to 1,000 times the heat flux capacity of a heat pipe having the same weight. "Boosted" embodiments of the heat link employing additional means for circulating the fluid, such as vapor jet pumps, powered at least in part by vapor from the capillary vaporizer, are also described. Some "boosted" heat links are capable of handling heat fluxes in the multi-megawatt range while having no moving parts except for check valves and the fluid itself.

Electrokinetic heat pipe

Abstract: A heat pipe for transporting a large quantity of heat within a small temperature difference provided with a tube, a wick, and a fluid that can transfer heat. The tube includes an evaporator section at one end and a condenser section at the opposite end thereof. The wick is disposed uniformly against the side walls of the tube and provides a capillary action to transfer the fluid from the condenser section to the evaporator section. Heat at the evaporator section causes the fluid to evaporate, wherein the vapor is then transmitted to the condenser section where the vapor condenses, thus giving up its latent heat, and is again transmitted to the evaporator section by the wick to define a continuous flow within the heat pipe. Electrodes are disposed within the tube, one electrode being disposed adjacent to the evaporator section, and the other electrode being disposed adjacent to the condenser section. When a potential difference is applied to the electrode, an electro-osmotic flow pumping is effected within the pipe, thereby, increasing the maximum heat capability of the heat pipe or overcoming any vapor lock present in the wick. Without the applied potential difference, the heat pipe functions as either an electrokinetic power generator or as a potential generator.

Method of making a heat pipe

Abstract: A heat-transfer device or heat pipe having an integral screenwick structure which provides relatively great contact area between the internal working fluid and the heat input. The screen wick is fabricated by a plurality of photographic etching and plating steps.

A feasibility study of heat-pipe-cooled leading edges for hypersonic cruise aircraft

Abstract: A theoretical study of the use of heat pipe structures for cooling the leading edges of hypersonic cruise aircraft was carried out over a Mach number range of 6 to 12. Preliminary design studies showed that a heat pipe cooling structure with a 33-in. chordwise length could maintain the maximum temperature of a 65 deg sweepback wing with a 0.5-in. leading edge radius below 1600 F during cruise at Mach 8. A few relatively minor changes in the steady-state design of the structure were found necessary to insure satisfactory cooling during the climb to cruise speed and altitude. It was concluded that heat pipe cooling is an attractive, feasible technique for limiting leading edge temperatures of hypersonic cruise aircraft.

Semiconductor device having heat pipe cooling means

Abstract: A semiconductor device has a semiconductor element arranged for double-sided cooling. At least one heat pipe is provided having one or more bends therein, one end of the heat pipe being in contact with the semiconductor element and the other end being in heat exchange relation with a heat exchanger provided with cooling flanges.

High heat flux heat pipe

Abstract: An improved heat pipe capable of conveying a greater heat flux than a conventional heat pipe is provided in practice of this invention. A heat pipe transfers heat from a heat source to a heat sink in the form of latent heat of vaporization of a fluid within the heat pipe. Hot vapor transfers heat from the heat source to the heat sink. Condensed liquid is returned from heat sink to the heat source through porous capillary material due to surface tension forces. The heat flux obtainable is limited by the available flow of returning liquid. In the improved heat pipe, the flow paths for liquid and vapor are serially segmented by impermeable barriers transverse to the direction of heat flow so that the distance of liquid flow in each segment is minimized. In zero gravity the heat flux obtainable is approximately proportional to the number of serial segments N into which the heat pipe is divided, that is, if the heat is transferred serially through N segments approximately N times the heat flux is possible as compared with a conventional heat pipe of the same overall dimensions. When operating against a gravity head, the maximum heat flux is about N2 times the heat flux of a conventional heat pipe. Thus a heat pipe segmented into 10 serial segments has approximately 10 to 100 times the maximum heat flux capacity of an unsegmented heat pipe of the same cross section and total length.

Method of fabricating a capillary heat pipe wick

Abstract: A conformal capillary wick for a heat pipe is fabricated by preparing a slurry composed of an organic solvent containing an organic binder in solution and powder particles of relatively high thermal conductivity in suspension; applying a layer of the slurry to the inner wall surface of the heat pipe casing, evaporating the solvent from the layer to recover the binder and utilize the surface tension forces of the binder to draw the particles together into a highly compacted condition wherein the particles are bonded to one another and to the casing wall by the binder, and the particles and binder define a myriad of capillary passages extending throughout and opening through the surfaces of the layer; and curing the binder to form a dimensionally stable capillary structure providing a capillary wick for transporting working fluid condensate from the condenser section to the evaporator section of the heat pipe.

Heat transfer apparatus with immiscible fluids

Abstract: A heat transfer device, defined here as a heat link, having a capillary vaporizer adjacent a heat source, transfers heat to a heat sink by vaporization and condensation of a heat transfer fluid within the device. A first passage is provided for conveying vapor from the capillary vaporizer to the heat sink. Another passage which is essentially a continuation of the first passage, conveys condensed liquid from the heat sink to the vaporizer, thus allowing the distance that the liquid must flow through capillary material to be quite short. Contact of the returning liquid with the surface of the vaporizer is assured by providing means for maintaining the temperature of the liquid in the return line at a sufficiently low temperature that any vapor will condense; or, alternatively, by having means for extracting any vapor formed in the returning liquid. In this manner, the heat link operates with high heat flux without any substantial resistance to liquid flow through a long capillary flow path. By thus replacing almost all of the liquid return wick, with its high resistance to fluid flow, of heat pipes with a low flow resistance liquid passage or conduit, the heat flux capacity of the heat link is greatly increased over that of the heat pipe while the quantity of porous material used and the heat link weight are considerably reduced so that a heat link typically has 10 to 1000 times the heat flux capacity of a heat pipe having the same weight. ''''Boosted'''' embodiments of the heat link employing additional means for circulating the fluid, such as vapor jet pumps, powered at least in part by vapor from the capillary vaporizer, are also described. Some ''''boosted'''' heat links are capable of handling heat fluxes in the multi-megawatt range while having no moving parts except for check valves and the fluid itself.

The Heat Pipe

Abstract: Publisher Summary This chapter classifies and evaluates the comprehensive literature collection composed of publications, papers presented at meetings, and reports of varying nature that appeared during the period from 1964 through midyear 1970 on heat pipe technology and on related topics. In the operation of a heat pipe, thermal energy is transferred from the evaporator to the condenser by continuous mass cycling and phase change of a suitable working fluid. In a heat pipe, the working fluid is continuously cycled by the surface tension forces of the fluid itself. It is this unique method of mass transfer that has both stimulated a growing interest in the heat pipe and has also proved to be one of the major impediments for a successful heat pipe operation. Theoretically, the heat pipe may be applied to almost a limitless number of thermal transport problems, which in general, can be subdivided into four broad topical categories depending on the particular feature of a heat pipe that is to be exploited. These areas of possible application are: (1) temperature flattening, (2) source–sink separation, (3) heat flux transformation, and (4) constant flux production.

Method and apparatus for removing heat from within a vacuum and from within a mass

Abstract: A method and apparatus for cooling elements generating heat within a vacuum and the center of a large mass of hot material including a heat pipe having the input end within a vacuum or a large mass of material and the output end exterior thereof, and means for subjecting the output end to an electrostatic field to materially increase the rate of heat transfer into the atmosphere.

Feedback controlled variable conductance heat pipes

Abstract: Feedback system monitors source temperature and makes necessary changes of area available for heat rejection by adjusting storage volume of noncondensible gas and position of vapor/gas interface.

Fuel elements for use in thermionic nuclear reactors

Abstract: 1,185,583. Nuclear power plant. EUROPEAN ATOMIC ENERGY COMMUNITY. 7 March, 1968 [14 April, 1967], No. 11145/68. Heading G6C. In a nuclear reactor thermionic fuel element, heat is removed by a heat pipe in which the thermionic elements are mounted. The thermionic units 10 are supported in the heat pipe 11, in which sodium vapour flows from the fission zone 16 to the condensing end 18. The condensate is returned to 16 through the capillary structure 19. Each thermionic unit is formed of nuclear fuel 12 in emitter envelope 13 which is supported in the heat pipe by the electrically insulating ring 17 which engages the emitter screen and cover 14, 15. The thermionic collector is formed by the pipe 11. With fuel elements stacked vertically, the emitter covers 15 of one element are connected in parallel by the heat pipe 11 of element above. In a further embodiment, the thermionic units have planar electrodes and are mounted in the upper surface of a heat pipe.

Bus bar electric power distribution system with heat pipe heat dissipating means

Abstract: Enclosed multi-phase power bus bar distribution apparatus made up of prefabricated ten-foot lengths or sections having joints which include closely stacked overlapping bus bar portions. Heat generated in the joint is led out of the joint by conductive heat-bleeding members which extend into close thermal contact with at least one bus bar of each phase at the overlapped portions. "Heat pipe" heat conducting members are provided in close thermal contact with portions of the heat-bleeding members and in close thermal contact with a heat-dissipating plate which dissipates heat to the ambient air. Fins are added to the heat-dissipating plate to enhance its heat dissipating ability. In another form, heat-bleeding members extend into close thermal contact with each of the bus bars of a prefabricated section intermediate the ends of the bus bars and "heat pipes" lead heat to a heat-dissipating cap plate. The heat-bleeding members and heat-pipe members are staggered or spaced along the length of the section.

Transient performance of electrical feedback- controlled variable-conductance heat pipes

Abstract: Steady state and transient response of heat source with temperature regulated by electrical feedback controlled variable conductance heat pipe

Cooling apparatus for infrared detectors

Abstract: A variable temperature dewar in which a heat load is thermally connected to a heat sink by a short heat pipe, the temperature of the load being varied by varying the pressure in the heat pipe to vary the boiling temperature of a cryogenic fluid contained therein, of which the liquid phase is in conductive thermal contact with the load and the gas phase is in conductive thermal contact with the sink

A variable conductance heat-pipe flight experiment

Abstract: Gas controlled variable conductance heat pipe for OAO-C onboard processor temperature stabilization, describing thermal performance tests under simulated flight conditions

Heat pipe cooled capacitor

Abstract: In a capacitor in which the electrodes are in the form of elongated conductive sheets separated by elongated dielectric sheets and wound in a compact convolute or roll form with exposed electrodes at each roll edge, heat dissipation is augmented by a chill plate in contact with one of the exposed sheet electrodes at a roll edge and by a plurality of heat pipes connected to the chill plate.

Carburetor having a heat pipe for vaporizing fuel

Abstract: A fuel vaporizing system for spark ignition internal combustion engines wherein a heat pipe filled with a narrow-range boiling point fluid is disposed to transfer heat from a heat zone to a vaporizing zone. The liquid fuel is vaporized in the vaporizing zone prior to being mixed with air.