Showing papers on "Heat pipe published in 1979"

Electrohydrodynamically Enhanced Heat Transfer in Liquids—A Review

Abstract: Publisher Summary This chapter serves as a useful synopsis of the field of electrohydrodynamically (EHD) coupled heat transfer in liquids, so the equations of motion are those of a viscous incompressible fluid. An exhaustive published bibliography of work on EHD coupled heat transfer is provided and reviews the principal contributions made by Kronig and Ahsmann. The conventional formulation of the equations of EHD is provided to facilitate discussion of various theoretical contributions. The classification of important parameters used in EHD heat-transfer research is summarized. Some important aspects of EHD coupled heat-transfer enhancement including a succinct set of conditions that define the various regimes are reviewed. Specific application of the complex electrohydrodynamic mechanisms involved in EHD coupled heat transfer in liquids is considered. Potential applications of EHD heat transfer include general enhancement of pool boiling for heat exchanger equipment. Certain advantages and disadvantages of EHD coupled heat transfer in low temperature and cryogenic high-voltage cables should be assessed. The boiling and condensation heat transfer and basic configuration of an EHD heat pipe using electromechanical flow structure to promote condensate return flow are diagrammatically represented. The list of experimental observations and theoretical conclusions are summarized and the principal results of the papers are reviewed.

Preventing apparatus for freezing of fountain nozzle

Abstract: PURPOSE: To prevent the freezing of fountain nozzle, by arranging one end of a heat pipe in the periphery of a nozzle case, and by allowing the other end to contact with a heat source. CONSTITUTION: When a fountain is stopped, fall of the open air temp. lowers the temp. of hydraulic fluid vapor in the heat pipe 21. When the temp. of the hydraulic fluid is lowered to a temp. not higher than that of soil, the part 21b, which is laid in the soil, of the heat pipe 21 is heated, and the hydraulic fluid is evaporated by the heat of the soil and flows to the other end 21a which is in contact with the nozzle case 1. At that time, the fluid vapor condenses to form liquid because the nozzle case is at a lower temp. than the soil, at the same time it releases condensing heat to the nozzle case 1. The condensed hydraulic fluid penetrates into a capillary material and is refluxed to the part 21b in the soil. Said circulation of the hydraulic fluid allows to heat the water contained in the nozzle case 1 with the heat held in the soil. Utilization of a main water pipe 4 as a heat source exerts the same effect. COPYRIGHT: (C)1981,JPO&Japio

Entrainment Limits in Heat Pipes

Abstract: The present work explores the physical basis for the entrainment limit in heat pipes and attempts to develop adequate quantitative criteria for the limit. Analogy is emphasized here between the entrainment phenomenon in heat pipes and the flooding phenomenon in countercurrent vapor-liquid flow systems. The maximum operating heat-transfer rates for various heat pipes due to entrainment limitation are established semiempirically by way of modifying existing flooding correlations. While the present results are successful in correlating the limited experimental data available, further experimental studies are needed in assessing the validity of the established criteria.

Integrated circuit micropackaging

Abstract: Thermal dissipation problems characteristic of micropackaging applications in integrated circuits can be eliminated by the use of a semiconductor heat pipe package. Additionally, the heat pipe package as herein disclosed can be employed for the creation of substantially constant temperature surfaces. In applications where a device requires controlled temperatures in order to achieve optimum operation, such as in photo voltaic converters, the packaging of the present invention provides a means for such temperature control. The heat pipe package comprises, in its simplest form, a closed vessel or box containing a heat transferring fluid. In its liquid state, the heat transferring fluid is transported along the interior surfaces of the box by means of a plurality of microgrooves through capillary action. The interior cavity of the heat pipe package or box provides a means for transport of the heat transferring fluid in the vapor state. The integrated circuits may be disposed in the semiconductor surface of the package itself, or mounted as dies in high density. The large number of intercommunications which are required between the high density of integrated circuits included with the micropackaging can be achieved by a combination of optical and electrical communication lines or buses.

Solar heat collector

Abstract: PURPOSE: To enhance the radiating effect by a method wherein the radiating portion of a heat pipe is formed of two plates laminated in a flat shape. CONSTITUTION: The heat receiving portion 3a of a heat pipe 3 having heat absorbing fins 10 is sealed in a transparent vacuum cylinder 1, while the heat servicing portion 3b of the heat pipe 3 which has unidirectional characteristic and no wicks is communicated with a heat radiating member 4. The heat radiating member 4 comprises two metal plates 4a, 4b laminated and bonded by roll bonding method of the like to form passages 5 for the working fluid. The passages 5 comprises branch passages 5b branched from a main passage, and the tip end of one of the branch passages 5b is projected and provided with a thinner wall, as compared to the other branch passages, to be used as an exhaust passage 6. COPYRIGHT: (C)1981,JPO&Japio

Heat recovery in a laundry system

Abstract: In a laundry system including a washer, a dryer, and a water heater, the improvement of using a heat pipe to recover waste heat, whether it be from the hot air exhaust of the dryer or from the conductive losses from the dryer and to transfer that heat to the feed water of the water heater.

Vapor Flow Calculations in a Flat-Plate Heat Pipe

Abstract: Steady laminar incompressible two-dimensional flow in a horizontal flat plate heat pipe with an adiabatic top plate was studied. For uniform evaporation and condensation rates, the Navier-Stokes equations and the continuity equation were solved. For radial Reynolds numbers Rer > 1, the velocity profiles were nonsimilar and asymmetrical. At Rer > 10, backflow was observed along the top plate, starting at the end of the condensation zone. At the highest /?er( = 50), the total pressure drop over the heat pipe was more than three times the value found from Poiseuille approximation. However, complete recovery of impulse pressure was found and the additional pressure losses could be fully attributed to increased frictional losses. Experiments with a porousplate model showed excellent agreement.

Indirectly heated aircraft probes and masts

Abstract: Aircraft probe or mast including heat pipe for indirectly heating the probe or mast thereby providing deicing. Heat for the heat pipe configured probe or mast is supplied by remote location of a heat source. The heat source may include a replacement plug in electric heater or a remote heat source such as an engine airbleed duct.

Uniform surface temperature heat pipe and method of using the same

Abstract: A heat pipe includes an elongated, heat conductive shell containing heat transfer fluid which is vaporizable and condensable, and cooling means within the shell to condense the heat transfer fluid from the vapor form to the liquid form and thereby to cool the shell to approximately the same temperature throughout its length. The cooling means can include a conduit or conduits running longitudinally inside the shell of the heat pipe and carrying a circulating coolant which can be a liquid or a gas. The substantially uniform cool surface temperature of the heat pipe adapts it for use as an efficient solar energy collector with the circulating coolant serving as a heat extracting medium. Alternatively, a row of photovoltaic cells may be mounted on the uniformly cool heat pipe shell and an elongated lens used to refract solar rays to impinge concentrated or high intensity solar energy onto the targets of such cells.

Passive solar heating and cooling panels

Abstract: A heat pipe is used to transfer heat from an outside solar panel into a building where the heat can be stored in a heat absorber. Various heat pipe structures are disclosed where the pipe passes through the wall of the building and where it has an end portion thermally contacting the solar panel. Heat transfer can be stopped by rotating the heat pipe, by the use of plungers and trap chambers in the pipe or by specially designed heat pipes that can be easily removed. The heat pipe can also be used to remove heat from the inside to the outside. The inside end portion of the heat pipe is in thermal contact with a heat absorber inside the building which contains a phase change material. Modular wall units can also be made having the solar panel and heat absorber integral on each side of the wall with the heat pipe in between.

Thermal control system

Abstract: In a space shuttle, payloads are individually temperature controlled by means of a liquid control loop in heat exchange relationship with both the payload and a radiator or shuttle cold plate. The liquid pump is driven at a variable speed to control the heat transferred between the load and the radiator or cold plate, and the motor may be reversed to by-pass the radiator through check valves. The radiator includes heat pipes seated in elongated, high thermal conductivity extrusions and retained therein by elongated springs. The motor is a brushless DC motor isolated from the pump by a magnetic clutch and thermal isolator. The motor is driven by a digital circuit which provides a single pulse to each set of windings during each energizing time frame. The width of that pulse is modulated to provide for speed control. Pulse width modulation is by means of a one-shot, the pulse duration of which is controlled by a speed control signal.

Cooling apparatus for electrical machinery

Abstract: In order to provide improved cooling for electrical machinery, especially A. C. generators for motor vehicles, with elimination of a rotating ventilating fan, the invention provides heat pipes disposed so that the evaporation regions of the heat pipes contact or surround the heat-producing parts of the generator, in particular the stator windings and the rectifying diodes. These regions communicate through sealed conduits with condensation regions that are located in places subject to lower temperatures that prevail near the heat producing elements. Disposed within the heat pipes are per se known capillary structures which transport condensed heat transport medium back to the evaporation region. Various embodiments are presented.

The Application of Heat Pipes on the Trans-Alaska Pipeline

Abstract: : The application of heat pipes on the Trans Alaska Pipeline is reviewed. The subjects addressed include the general functioning of a heat pipe, the specific heat pipe design used, the different situations where heat pipes were employed, the methods used to develop the heat pipe design, the methods used to monitor the operating heat pipes, and the performance of the heat pipes. The discussion is qualitative in nature. Quantitative information is largely omitted to allow coverage of a broad area, and because it may be considered proprietary. Nevertheless, the information presented here should give a good appreciation of the quality and complexity of the heat pipe design. The information should also be useful in developing heat pipes for use in other cold regions applications. (Author)

Long-term ice storage for cooling applications

Abstract: A device is providing for cooling a stored material and then for later use of the cold thus stored. The device includes a tank containing a liquid such as water which is frozen by means of a reflux condenser heat pipe.

Integral storage collector solar heating system

Abstract: In an integral storage collector solar heating system, water heated in a conventional hot water heater is first preheated in an integral storage collector. The storage collector includes a heat storing medium, preferably clean water, in a storage tank. Water to be heated is forced by line pressure through heat exchange pipes immersed in the heat storing water. The heat of fusion of the storing water prevents freezing of the line water. To preclude excessive pressure in the heat storage tank with high temperatures of the heat storing water, a heat pipe is provided to act as a large heat leak at about the vaporization temperature of the water. Also, a pressure relief valve is provided. The system avoids freezing and contamination of the water and does not require temperature control circuitry or a pump.

Thermal jacket for elongated structures

Abstract: An arrangement for reducing non-symmetrical, thermally induced strains in a gun tube (12) comprising a heat pipe jacket (18) in thermal engagement with the gun tube to provide both high radial and circumferential thermal conductance from the tube.

Spherical heat pipe metal-hydrogen cell

Abstract: A metal-hydrogen cell (e.g., silver-hydrogen or nickel-hydrogen) of heat pipe design wherein a central heat pipe serves as a thermal path, a positive plate conductor and terminal, and a mechanical support for the stack. The positive plates are electrically, mechanically and thermally connected to the heat pipe in the stack center. The negative plate terminals are at the outside edge of the stack. The pressure vessel may be of spherical configuration to provide a light weight design which has a two to one stress advantage in hoop stress over a cylinder with the same wall thickness and internal pressure.

Ion drag pumped heat pipe

Abstract: Conventional heat pipe performance can be improved by reducing the dependency upon the capillary pumping limitation. Electrodes mounted either in the working fluid vapor or its condensate produce an ion flow directed axially and in the same flow direction. The ion flow, through collision phenomena, picks-up the surrounding low velocity stream, increases its momentum and generates additional pumping pressure for the condensate. Performance can be improved even when low surface tension working fluids are used.

Development of a Liquid-Trap Heat Pipe Thermal Diode

Abstract: An all-aluminum axial-groove liquid-trap heat pipe diode, 470 mm long and 10 mm o.d., has been developed with a forward-mode performance of nearly 90 Wm, when ammonia is used as the working fluid at 20°C. The diode is bendable, of simple design, and of reliable performance. A mathematical model, based on an energy balance for evaporator and trap, has been developed for predicting the transient shutdown of the diode. Theroretical predictions and experimental results are in good agreement. The time for complete shutdown of the diode is on the order of 20 min. The respective shutdown energy is about 4 Wh. A reverse-mode heat flow of about 1.5 W has been measured. Thereby, a turndown ratio of about 300 has been established.

Cylindrical heat exchanger using heat pipes

Abstract: This invention relates to an improvement in a heat exchanger of the type using heat pipes which permits reduction in size of the heat exchanger and enhancement in heat exchange efficiency and more particularly to a cylindrical heat exchanger principally comprising a cylindrical or polygonal tubular casing provided with openings in the middle parts of its upper and lower sides and in its circumferential side, a transverse partition plate which divides the inside of the casing into upper and lower parts and a group of vertical heat pipes arranged to pierce through the peripheral portion of the partition plate in an annular plan configuration as a whole.

Solar heat collector with heat pipes

Abstract: A passive solar assistance device for use with a heat pump having a heat transfer fluid inlet and outlet, with means for circulating the fluid, a tank for containing an amount of the fluid, and at least one solar heat pipe having one end extending into the tank and adapted to be in contact with the fluid. At its opposite end the heat pipe is provided with a solar receiving device, such as an enclosed box having one or more transparent walls facing the sun or a plate construction comprising an extension of the heat pipe itself. In its heating mode, heat pipe is mounted at an angle of at least 30°, with the end associated with the solar receiving device in the lowermost position so that the heat pipe acts as a one way heat valve conducting heat from the solar receiving device to the fluid in the tank but not in the opposite direction. The heat pipe may be pivotally mounted to provide for either a heating mode or cooling mode.

Osmotically pumped environmental control device

Abstract: An osmotically pumped environmental control system (10) comprises a closed circuit heat pipe (12) including an osmotic pump (13) with solvent and solution reservoirs (18, 14) separated from one another by a solvent permeable membrane (20). Heat is inserted into the closed path at an evaporator (22) from high temperature sources and heat is wihdrawn from the system by first and second stage cooling modules (38, 40) to withdraw heat therefrom. A further heat input (30) from low temperature sources slightly warms the condensate for return to a solvent reservoir (18).

Method and apparatus for removing heat from a workpiece during processing in a vacuum chamber

Abstract: A workpiece (16), for example a magnetic bubble memory wafer, is held in place, and heat is removed from it by an expandable heat pipe (22) during a process performed in a vacuum as, for example, a sputter etch process. The expandable heat pipe (22) includes two plates (24, 26) joined by a bellows (28) to form a sealed chamber containing a vaporizable liquid such as water. During loading of the wafers the heat pipe (22) is compressed by atmospheric pressure and thereby facilitates easy assembly of the wafer (16) and heat pipe (22) into a holding fixture (10) which in turn is bolted to a cooling plate (30) situated inside a vacuum chamber. When the chamber is evacuated, the heat pipe (22) expands to hold the wafer (16) in place and form a good thermal path from the wafer (16) to the cooling plate (30). In an alternate embodiment the heat pipe (22) does not completely fill the gap from the wafer (16) to the cooling plate (30) in a vacuum at room temperature, but rather expands to fill the gap when the heat pipe (22) is heated by the wafer (16). The expanding heat pipe (22) holds the wafer (16) at a constant, predetermined temperature above the temperature of the cold plate.

Augmenting the Condenser Heat-Transfer Performance of Rotating Heat Pipes

Abstract: A rotating heat pipe assembly was tested at rotational speeds of 700, 1400, and 2800 rpm using distilled water as the working fluid. Tests were made during film condensation on several copper condensers, including smoothwalled cylinders, an internally finned cylinder, and a truncated cone. The truncated cone surface was also promoted for dropwise condensation using n-octadecyl mercaptan in octanoic acid. Heat-transfer performance improved with increasing rotational speed. The internally finned cylinder and the truncated cone showed a 100% improvement over the equivalent smooth-walled cylinder. Dropwise condensation showed substantial improvement over film condensation, primarily at low rotational speeds. Nomenclature cp = specific heat gc = gravitational constant m = mass rate of flow Q = heat-transfer rate R = radius AT = cooling water temperature difference p = density a = surface tension o> = angular velocity

Heat pipe deicing apparatus

Abstract: A heat pipe deicing system is disclosed for preventing accumulation of ice on portions of structures such as the deck, handrails, and ladders of a fishing vessel operating in very cold oceans. The heat pipe includes an evaporator in contact with a source of heat such as exhaust gases of an engine, one or more condensers positioned above the evaporator to cover surfaces to be deiced, and an insulated transition section for transporting a heat transfer fluid between the evaporator and condenser. The transition section and condenser have legs arranged to provide multiple passageways which assure continuous gravity-assisted return flow of condensed heat transfer fluid to the evaporator and a high level of deicing capacity even during pitching and rolling of the structure on which the deicing system is installed.

Heat exchanger arrangement for cooling lubricant for vertical electric motor thrust bearing

Abstract: A vertical electric motor embodying the invention has a housing including a cylindrical frame enclosing a stator, a rotor and a shaft affixed to the rotor and mounted for rotation about a vertical axis, upper and lower end frames, a heat generating thrust bearing supported on the top end frame and rotatably supporting shaft and rotor, and a lubricant-receiving reservoir within the motor enclosure above the top end frame and enclosing the thrust bearing. Liquid lubricant within the reservoir is in heat absorbing and lubricating relation with the thrust bearing. A plurality of finned heat transfer heat pipes are supported within the reservoir with their evaporator end submerged in the lubricant and their condenser end exposed to air within the motor housing above the top surface of the lubricant and enhance heat transfer from the lubricant to the atmosphere. Air inlet apertures and air exhaust apertures are provided in the motor enclosure above the reservoir, and a plurality of fan blades rotatably driven from the shaft draw a high volume of air into the space within the motor enclosure above the lubricant and force the air past the condenser end of the heat pipes and out of the exhaust apertures to thereby substantially increase cooling of the thrust bearing.

Heat transfer system

Abstract: A heat transfer system disposed between a heat-emitting zone or heat source and a heat-consuming zone or heat sink in accordance with the heat pipe principle. A vacuum-tight hose conduit is arranged between the heat-emitting zone and the heat-consuming zone at least along a partial region of a heat transfer path. The respective ends of the vacuum-tight hose conduit are threadedly connected in the heat transfer path with the vacuum-tight hose conduit being resistant to the heat transfer medium and being provided with an internal capillary structure for enabling a return of the condensate.

Solar collector with heat pipe

Abstract: A solar collector is disclosed the constructional structure of which has been simplified in such a way that the condenser system of the collector is inserted in the channel through which the gaseous or liquid heat-transfer medium flows by means of a sealing system comprising a gasket member and screwably operable tightening means. Assembly and overhauling of the condenser system are greatly facilitated.

Recyclable-fuel engine system

Abstract: A recyclable-fuel engine system designed for use in a vehicle. The system includes a hydrogen-producing catalytic unit having plural catalytic beds, and a hydrogen-fueled engine having combustion and exhaust chambers. The catalytic beds, when supplied with heat, catalyze a reduced form of a hydrocarbon carrier to hydrogen and a dehydrogenated form of the carrier. One of the catalytic beds is supplied heat by direct heat transfer from the engine's exhaust chamber. The remaining catalytic beds are supplied heat by heat pipes receiving heat from the combustion and exhaust chambers. The hydrogen produced in the catalytic unit is supplied to the engine, to power the same. Also disclosed herein are apparatus and method for regenerating the catalytic beds periodically.

Heat-sinking system for electrical components in cabinet - has flexible heat pipe connecting component support to ribbed section

Abstract: The heat-sinking system removes heat from components in a switching cabinet and consists of a flexible ready-made heat pipe. the pipe is connected at one end to the plate on which the components are mounted and at its opposite end to a heatsink comprising fins. The pipe is seam welded metal and is corrugated. Several such heat pipes may be fitted. The pipe is typically filled with water so that heat is transferred from one end to the other by a continuous evaporation and condensation process.