Showing papers on "Heat pipe published in 1981"

Glass heat pipe evacuated tube solar collector

Abstract: A glass heat pipe is adapted for use as a solar energy absorber in an evacuated tube solar collector and for transferring the absorbed solar energy to a working fluid medium or heat sink for storage or practical use. A capillary wick is formed of granular glass particles fused together by heat on the inside surface of the heat pipe with a water glass binder solution to enhance capillary drive distribution of the thermal transfer fluid in the heat pipe throughout the entire inside surface of the evaporator portion of the heat pipe. Selective coatings are used on the heat pipe surface to maximize solar absorption and minimize energy radiation, and the glass wick can alternatively be fabricated with granular particles of black glass or obsidian.

Pump-assisted heat pipe

Abstract: A closed-loop heat transfer system comprises a heat pipe (10) and an external liquid-phase pump (11). The heat pipe (10) includes an evaporator (12) and a condenser (13) connected by a conduit (14). The evaporator (12) is a hollow structure having an interior surface defining an evaporation region in which a working field in liquid phase absorbs heat from a heat source by evaporation. A capillary pumping structure, e.g., capillary channels (30) or a fine-mesh screen (41), is provided on or adjacent the interior wall of the evaporator (12). Evaporated working fluid laden with heat is thermodynamically driven substantially adiabatically via the conduit (14) from the evaporator (12) to the condenser (13), wherein the working fluid rejects heat to a heat sink by condensation. Condensed working fluid is thereupon returned from the condenser (13) to the evaporator (12) via external conduits (22, 15) by means of the liquid-phase pump (11). The capillary pumping structure inside the evaporator (12) serves to maintain a constant supply of working fluid in liquid phase adjacent the interior surface of the evaporator (12), thereby promoting efficient transfer of heat from the heat source to the working fluid in the evaporator (12). There is no limitation on the length of the heat pipe (10) caused by capillary pumping requirements of the system. Pursuant to 37 CFR 1.72(b), the foregoing abstract shall not be used for interpreting the scope of the claims herein.

The monogroove high performance heat pipe

Abstract: The development of the monogroove heat pipe, a fundamentally new high-performance device suitable for multi-kilowatt space radiator heat-rejection systems, is reported. The design separates heat transport and transfer functions, so that each can be separately optimized to yield heat transport capacities on the order of 25 kW/m. Test versions of the device have proven the concept of heat transport capacity control by pore dimensions and the permeability of the circumferential wall wick structure, which together render it insensitive to tilt. All cases tested were for localized, top-side heat input and cooling and produced results close to theoretical predictions.

Heat pipe oven of well‐defined column density

Abstract: A modification of the concentric heat‐pipe oven is presented which exceeds the conventional heat pipe oven because of a better defined column density and a significantly shorter warm‐up time for achieving stable operation. Similar to the conventional concentric heat‐pipe oven, the modified version provides metal‐vapor–noble gas mixtures with adjustable partial pressures. As an example, third harmonic experiments have been carried out in a strontium–xenon mixture and phase‐matching curves have been measured which demonstrate the well‐defined column density.

Heat-producing elements with heat pipes

Abstract: The PC-boards are contained in sealed enclosures, and serially effective heat pipe systems conduct thermal energy from the respective sources of development (e.g., power transmitters) to the top and from there to a heat pump system. Stacking such units and operating the heat transfer partially in parallel is disclosed.

Solar heat collector

Abstract: A solar heat collector comprises an evacuated transparent pipe; a solar heat collection plate disposed in the transparent pipe; a heat pipe, disposed in the transparent pipe so as to contact with the solar heat collection plate, and containing an evaporable working liquid therein; a heat medium pipe containing a heat medium to be heated; a heat releasing member extending along the axis of the heat medium pipe and having thin fin portions extending from the axis to the inner surface of the heat medium pipe; and a cylindrical casing surrounding coaxially the heat medium pipe to provide an annular space which communicates with the heat pipe. The evaporable working liquid evaporates, receiving solar heat collected by the heat collection plate. The resultant vapor heats the heat medium through the heat medium pipe and the heat releasing member.

Pool-Boiling Heat Transfer in Liquid Nitrogen

Abstract: An experimental study was conducted on pool-boiling heat transfer from an electrically heated horizontal wire to saturated liquid nitrogen at atmospheric pressure Experimental results of heat transfer characteristics in both nucleate- and film-boiling regimes, critical heat flux and minimum heat flux were analyzed and compared with various correlations In addition, photography was used to obtain information concerning the vapor-bubble and vapor-film behaviors around the heating wire These data of microcharacteristics were utilized for evaluating theoretical models of nucleate-boiling mechanism proposed by other investigators Transient conduction to the relatively cold (saturated) liquid, which came into the space vacated by the departing bubble and contacted with the heating surface, was found to be important for high heat transfer rates associated with nucleate boiling

Simultaneous measurements of thermopower, thermal conductivity, and electrical resistivity between 1.2 and 350 K

Abstract: We described a fast‐cooling cryostat with a novel cooling system using a nitrogen heat pipe. The principal feature of the cryogenic assembly is an evacuated calorimeter containing a heat sink which can be maintained successively at 1, 4.2, and 77 K during the experiment. This allows sample regulation from 1.5 to 350 K. An electronic circuit including noise filters and nanovoltmeters is used to measure the electrical resistivity, thermal conductivity, and thermoelectric power of conducting or semiconducting materials. We used a commercially available Au–Fe–chromel couple as the working thermocouple. First, we calibrated it against germanium and platinum resistance thermometers, and compared the thermoelectric scale so obtained with previous calibrations. We report a preliminary test on pure lead which enabled us to obtain the absolute thermoelectric powers of AuFe and chromel and also to estimate the parasitic radiative heat transfer during thermal conductivity measurements. We also report the three transport properties of the title for an amorphous Ce0.3Al0.7 alloy prepared by sputtering a crystalline CeAl3 compound. The thermal conductivity and electrical resistivity were essentially those associated with amorphous materials. The thermoelectric power exhibited structure at low temperatures which suggests that a weak magnetism appeared in this glassy structure formed from the typical Kondo compound CeAl3.

Dual axial channel heat pipe

Abstract: A heat pipe comprising an elongated sealed metallic envelope having at least a pair of longitudinal channels extending along the length thereof. One of the channels is for the circulation of the vapor phase of the working medium in operation and the other for the liquid phase and capillary means are provided to furnish fluid communication therebetween. Dedicated vapor and liquid channels result in low viscous pressure drops, the capillary communication means and circumferential grooving in the vapor channel provide high capillary pressure differences, and circumferential grooving is provided to furnish the high evaporation and condensation film coefficients required. To support higher heat fluxes, wicking can be used to augment the capillary flow from the liquid channel. To support higher evaporator heat flux without the need for wicking means, the heat pipe can be provided with more than one liquid channel, each communicating with the vapor channel by capillary means. The heat pipe can be provided with an integral fin or equivalent means for rejection of heat by radiation to ambient or for attachment to a source of heat in the evaporator region thereof.

Design, Analysis, and Tests of a Shuttle-Type Heat-Pipe-Cooled Leading Edge

Abstract: A one-half-scale heat-pipe-cooled leading edge model was designed and fabricated to verify feasibility and performance of a full-scale Shuttle-type orbiter design. Model performance was investigated experimentally by radiant heating and aerothermal tests and analytically by using a simple technique which predicts heat pipe startup from the frozen state and also predicts transient and steady-state thermal behavior. Analytical results agree well with experimental results for startup and steady-state heat pipe operation. The results indicate that variations in angle of attack and roll orientation had a negligible effect on heat pipe performance. The heat pipes effectively isothermalized the leading edge, and reduced peak temperatures to levels compatible with the use temperatures of superalloys. Results of these tests demonstrated the durability of the heat-pipe-cooled leading edge in withstanding Earth-entry thermal and mechanical loads and indicate that the use of heat pipes in leading edge structures is a reliable concept for fully reusable hypersonic cruise and space transportation systems.

Heat pipes for use in a magnetic field

Abstract: A heat pipe configuration for use in a magnetic field environment of a fusion reactor. Heat pipes for operation in a magnetic field when liquid metal working fluids are used are optimized by flattening of the heat pipes having an unobstructed annulus which significantly reduces the adverse side region effect of the prior known cylindrically configured heat pipes. The flattened heat pipes operating in a magnetic field can remove 2--3 times the heat as a cylindrical heat pipe of the same cross sectional area.

External/internal heater for molding of plastics

Abstract: A nozzle for use in an injection molding machine. The nozzle comprises a tripartite body having an inlet, an outlet and an interconnected passageway extending therethrough. A heat pipe is located within the center of the body and portions of the passageway are disposed about the heat pipe. A resistance heating band is mounted on the body to conduct heat therethrough to heat the heat pipe. The heat pipe serves to heat plastic flowing through the surrounding passageway portions to the outlet.

Electrostatically pumped heat pipe and method

Abstract: The heat pipe has a condensing area at one end and an evaporating area at the other end. An ion drag pump is within the condensing area to receive dielectric refrigerant condensate in its inlet. There is a liquid carrying tube having one end connected to the pump outlet and having its other end terminating adjacent the evaporating area to discharge refrigerant condensate therein. The evaporating area has heat receiving flow paths into which the condensate is adapted to flow and be vaporized, there being a vapor flow path from the evaporating area through which the vaporized refrigerant returns to the condensing area. The method includes cooling one end of the heat pipe to liquefy refrigerant therein to form a condensate, flowing the condensate into an ion drag pump and applying a sufficiently high voltage across a cathode and anode of the pump to produce ions in the refrigerant condensate, the ions then being accelerated toward the anode so as to create fluid motion and pumping action through the pump inlet. The condensate is thereby pumped through a closed-wall flow path to the other end of the heat pipe to which heat is applied to evaporate the refrigerant into a vapor. The vapor from the other end is then flowed to the one end of the pipe in which the condensate is formed by cooling.

Heat pipe cooled probe

Abstract: The basic heat pipe principle is employed to provide a self-contained passively cooled probe that may be placed into a high temperature environment. The probe consists of an evaporator region 13 of a heat pipe 10 and a sensing instrument 17. Heat is absorbed as the working fluid 22 evaporates in the probe. The vapor is transported to the vapor space 14 of the condenser region 15. Heat is dissipated from the condenser region and fins 20 causing condensation of the working fluid, which returns to the probe by gravity and the capillary action of the wick 18. Working fluid, wick and condenser configurations and structure materials can be selected to maintain the probe within an acceptable temperature range.

Heat-pipe type solar water heater

Abstract: A heat-pipe type solar collector comprises as its principal portion a plurality of heat pipes arranged in parallel with each other and having vaporizing portions and condensing portions, and a plurality of heat collector plates traversing the heat pipes and arranged in parallel with each other, the vaporizing portion of each heat pipe penetrating through and fixedly mounted to the collector plates in intimate heat conductive relation therewith, and each collector plate having a lower portion bent substantially perpendicular to the remaining portion to cover a space between itself and an adjacent collector plate. According to this arrangement, solar heat can be effectively collected by the collector plates and transmitted to the heat pipes with a negligible heat loss. Thus the heat collecting efficiency of the water heater can be remarkably enhanced.

Engine unit with lubricant cooling

Abstract: An engine unit adapted to be lubricated by a liquid lubricant with a lubricant reservoir as well as a lubricant cooling The cooling takes place by way of at least one heat pipe, with the heat pipe having a heat absorbing portion adapted to be exposed to the lubricant and a heat transmitting portion adapted to be exposed to surrounding air The engine unit may be an internal combustion engine, a gear system such as a change-speed transmission or differential transmission of a vehicle drive axle

Magnetic two-phase thermosiphon

Abstract: A heat pipe or thermosiphon device is provided which may be configured for operation in various temperature regimes from cryogenic to elevated temperatures and in gravity or other orientation sensitive environments, as well as zero-gravity or other orientation insensitive environments. The invention comprises a heat pipe, containing a magnetically susceptible liquid as the working fluid, surrounded by an electro-magnet or permanent magnet which produces a magnetic field gradient which interacts with the magnetically susceptible liquid to produce an artificial body force field analogous to, but which may be substantially greater than, the gravitational force field, for separation of the liquid from gaseous phases of the magnetically susceptible working fluid within the heat pipe.

Three-way heat pipe

Abstract: A three-way heat pipe configured in a generally Y-shape having a condenser-evaporator or heat-sink end, an evaporator arm and a condenser arm. In addition to conventional internal pumping the heat pipe is mechanically pumped externally from the heat-sink end to the evaporator arm. Heat transfer can take place between any two of the three elements by thermostatically controlling the external pump. Heat or cold may be stored in a suitable medium surrounding the condenser-evaporator end of the pipe for later transfer through the condenser or evaporator ends used as heat exchangers without a secondary circulation system. Heat transfer may also take place directly between the evaporator and condenser arms without storage. In the preferred embodiment of the heat storage configuration, a valve is placed in the condenser arm to prevent unwanted heat transfer. A system of three-way heat pipes can provide long duration thermal storage of heat or cold energy which can be later used for space heating and/or cooling of buildings.

Manufacture of heat pipe

Abstract: PURPOSE:To obtain a highly precise quantity of working liquid, prevent air penetration and make properties uniform by providing a valve at the top of an unfinished heat pipe, inserting the bottom into a working liquid inside a tank, replacing an air inside an unfinished pipe with a working liquid vapor from the valve and finally introducing the working liquid into the unfinished pipe. CONSTITUTION:A three-point valve 9 is provided at the top of an unfinished heat pipe 1 and the bottom is inserted into a working liquid inside a liquid tank 11 up to a position to meet a hermetically contained quantity. Then a working liquid vapor 5a is introduced into the unfinished pipe 1 from a channel 10a. Next, a tubular passage 10a is closed and a tubular passage 10a is opened to expose the unfinished pipe 1 to an atmosphere. Consequently the working liquid 5 inside a liquid tank 11 flows into the unfinished pipe 1, pushing up a working liquid 5a inside and discharging a vapor through a flow passage 10b. When a prearranged hermetically contained quantity is filled, a valve 9 is closed and the unfinished pipe 1 is pulled out of a liquid tank as it is. Following this procedure, the upper and lower ends are pressed, sealed and cut. In this manner, it is possible to obtain a highly precise quantity of hermetically contained working liquid, prevent air penetration and make properties uniform.

Entirely passive heat pipe apparatus capable of operating against gravity

Abstract: The disclosure is directed to an entirely passive heat pipe apparatus capable of operating against gravity for vertical distances in the order of 3 to 7 meters and more. A return conduit into which an inert gas is introduced is used to lower the specific density of the working fluid so that it may be returned a greater vertical distance from condenser to evaporator.

Solar collector comprising an absorber plate which exchanges heat with the evaporator section of a heat pipe

Abstract: There is provided a solar collector comprising a metal heat pipe having an evaporator section and a condenser section. A metal tube is spaced from and surrounds the evaporator section, one end of such metal tube being closed and the other end being open. A metal solar heat absorber plate is thermally conductively connected to the metal tube. An evacuated transparent glass envelope is spaced from and surrounds the metal tube and the absorber plate connected thereto, such envelope being joined to the open end of the metal tube by means of a glass-metal seal. A thermally conductive medium fills the space between the metal tube and the evaporator section of the heat pipe.

Heat storage pond and power plant using same

Abstract: A heat storage pond comprises a heat storage liquid covered by a non-liquid insulating layer that floats on the liquid and is thick enough to thermally insulate the latter against significant conductive heat loss to an ambient medium above the insulating layer which may be an aqueous or a non-aqueous gel. The medium above the gel may be a layer of water which operates as a heat sink for a power plant whose heat source is the heat storage layer. The power plant may include a heat engine, such as an organic working fluid turbine, which extracts heat from the heat storage liquid, the layer of water above the gel serving as a condenser for the turbine.