Showing papers on "Heat pipe published in 1989"

Ceramic heat pipe wick

Abstract: A wick for use in a capillary loop pump heat pipe. The wick material is an essentially uniformly porous, permeable, open-cell, silicon dioxide/aluminum oxide inorganic ceramic foam having a silica fiber to alumina fiber ratio, by weight, of about 78 to 22, respectively, a density of 6 lbs/ft 3 , and an average pore size of less than 5 microns. A representative material having these characteristics is Lockheed Missiles and Space Company, Inc. HTP 6-22. This material is fully compatible with the FREONs and anhydrous ammonia and allows for the use of these very efficient working fluids, and others, in capillary loops.

Heat pipe cooling plate

Abstract: A flat cooling plate which is assembled with individual heat pipes which are annealed, flattened tubes with sintered wicks formed within them. The completely constructed and pre-tested heat pipes are set into slots in a spacer plate which is sandwiched between two unslotted flat sheets. For assembly, bonding material is placed between the slotted plate and unslotted sheets, and the assembly is heated to the bonding material working temperature while compressed in a press in order to prevent damage from excessive internal heat pipe pressure.

Heat Transfer Characteristics in Two-Phase Closed Conventional and Concentric Annular Thermosyphons

Abstract: The heat transfer in the condenser sections of conventional and annular two-phase closed thermosyphon tubes has been studied experimentally and analytically. In addition, the results of a series of experiments on the flooding phenomena of the same thermosyphons are reported. Freon 113 and acetone were used as working fluids. An improved correlation was developed to predict the performance limits of conventional thermosyphons using the present and previously existing experimental data for flooding with different working fluids. The prediction of the theoretical Nusselt number for the situations associated with measured heat transfer coefficients in the condenser section indicated that the effect of interfacial shear on the film flow is small. The increase of the experimental reflux condensation heat transfer coefficients over theoretical predictions is attributed to waves at the vapor-liquid interface.

High efficiency heat exchanger

Abstract: A high efficiency deployable heat radiator system for radiating heat generated at a source of heat aboard an orbiting spacecraft or like vehicle is described which comprises a first subsystem for circulating liquid heat exchange medium into heat exchange relationship with the heat source and for conducting vaporous medium generated at the heat source to a manifold; one or more interconnected movable radiator panels each including a pair of spaced wall members defining heat radiating surfaces; a plurality of heat pipes each having an elongated condenser end disposed between wall members of the radiator panels and in heat exchange relationship with the heat radiating surfaces; a manifold for conducting vaporous medium from the source into heat exchange contact with the evaporator ends of the heat pipes; an interface structure interconnecting the evaporator end of each heat pipe with the manifold and including a tubular member enclosing each evaporator end for conducting vaporous heat exchange medium into contact with the evaporator end and conducting condensed heat exchange medium back toward the source of heat; and wherein each heat pipe includes a flexible portion between the interface structure and the first panel and between panels so that the panels may be selectively moved between folded and deployed positions. The evaporator ends of the heat pipes and the inner surface of the tubular members of the interface structure are preferably grooved to promote heat exchange at the evaporator ends of the heat pipes.

Temperature regulating container

Abstract: A temperature regulating container with a heater and a metal block in which test tubes with test samples are therein inserted and kept isothermally provides a plurality of heat pipes embedded in the metal block and extended to the heater section located at bottom of the metal block uniformally maintain the temperature in the metal block. Heat tubes are further extended downwardly to a cooling chamber provided at the bottom of heater such that when a cooling medium, water or air flows in the cooling chamber, the metal block is cooled respondingly provide accurate cooling of test samples in test tubes according to a desired program.

Performance Characteristics of a Concentric Annular Heat Pipe: Part I—Experimental Prediction and Analysis of the Capillary Limit

Abstract: This paper describes the design, testing, and theoretical capillary limit prediction of a new heat pipe configuration, which is the concentric annular heat pipe. The concentric annular vapor space. With this arrangement, capillary wicks can be placed on both the inside of the outer pipe and the outside of the inner pipe. This design heat pipes, since the cross-sectional area of the wick as well as the surface area for heating and cooling are increased. The heat pipe was tested for the temperature distribution in the three sections of the heat pipe under various tilt angles and heating loads through the inner and outer pipes in the evaporator section. A simple analysis for the prediction of the capillary limitation of the concentric annular heat pipe is presented.

Performance Characteristics of a Concentric Annular Heat Pipe: Part II—Vapor Flow Analysis

Abstract: The solutions of the equations of fluid motion for compressible and incompressible flow in a concentric annular heat pipe have been analyzed In addition, a similarity solution is presented that can predict the pressure losses in all the segments of the concentric annular heat pipe as well as conventional heat pipes A theoretical analysis to predict the sonic limit for this new pipe is also presented

Method of using a PCM slurry to enhance heat transfer in liquids

Abstract: A method of obtaining enhanced heat transfer in a closed loop thermodynamic system is disclosed. A two-component heat transfer fluid comprising a carrier fluid and a plurality of discrete reversible latent energy transition material particles. The fluid slurry is circulated about the loop and the loop is tuned so that a minimum temperature differential exists between the thermal source and sink in order to maximize the latent heat transport by adjustment of the heat transfer fluid flow rate, the rate of thermal energy input into the heat transfer fluid and the rate of cooling of heat transfer fluid.

Carbonated liquid refrigeration system

Abstract: A separate refrigeration system in a conventional refrigerator (10) for dispensing a chilled carbonated liquid such as water or a beverage from the front door (18) of the refrigerator (10) and is comprised of a refrigerator having a freezer compartment (12) wherein there is located a condenser (52). The condenser (52) is interconnected with a combined evaporator-carbonator unit (36, 50) located in the front door (18). The freezer compartment (12) accordingly acts as a heat sink for the condenser (52). The evaporator unit (50) being integral with the carbonator (36), operates to chill the carbonator (36). When desirable, the condenser (52) and evaporator (50) can be replaced by a liquid heat transfer system having a heat absorbing coil assembly (111) located in the carbonator (82") and a heat dissipating coil assembly (113) in the freezer compartment (62) or by a constant temperature heat pipe (106) having its heat dissipating end (112) located in the freezer compartment (62) while its heat absorbing end (110) is located in the carbonator (84').

Heat-pipe type cooler

Abstract: PURPOSE: To obtain a compact and light cooler wherein cooling performance is improved and the number of mounted heating elements is increased by constituting the cooler with three base plates on the outsides of which element mounting surfaces are provided, on the insides of which heat-pipe attaching parts are provided, and which are arranged in the U-shaped cross sections and the like, heat pipes, a plurality of fins, and a forced air cooling fan. CONSTITUTION: An element mounting surface 1a is provided at the outside of each of first to third base plate 1, 1A, and 1B. A heat-pipe attaching part 1b is provided at the inside of each of the base plates 1, 1A and 1B. The first to third base plates 1, 1A and 1B are arranged at three surfaces which have the U-shaped cross sections and which are intersected at right angles. Evaporating parts are attached to the heat- pipe attaching parts 1b of the first to third base plates 1, 1A and 1B. The condensing parts of one or more heat pipes 2, 1A-2C are bent and raised. A plurality of fins 3 are attached to the condensing parts of the heat pipes 2, 2A-2C. A forced air cooling fan 4 is provided on any surface which is intersected with the fin 3 at a right angle. The cooler is constituted in this way. For example, the base plates 1, 1A and 1B are manufactured by using a material such as copper or aluminum by an extrusion method, a die casting method or the like. The attaching recess parts 1b are formed at the inside. COPYRIGHT: (C)1991,JPO&Japio

Heat exchanger for cooling and method of servicing same

Abstract: A heat exchanger for cooling enclosures, typically electronic enclosures, has a box with a heat pipe type exchange element and upper and lower fan units. A novel element holder and box structure and arrangement of components provides for safety, NEMA-12 sealing, easy access and cleaning without tools, and enables the exchanger to be inverted end-for-end and mounted either on the inside or outside of the exchanger while providing a cover that easily comes off for service. The exchanger has an ambient fan and motor and a heat load fan and motor normally inside the box, and both fan and motors and the exchanger are movable to alternative positions for service. A method of servicing a heat exchanger is provided wherein two fans and motors, and a heat exchanger sequentially are unlocked and moved to alternative service positions.

Combination hot water heater-refrigeration assembly

Abstract: A combination hot water heater-refrigeration assembly includes a refrigeration assembly coupled to a hot water tank via a heat pipe. The heat pipe has the heat releasing end thereof near the bottom of the hot water tank.

Thermal actuated switchable heat pipe

Abstract: A thermal actuated switchable heat pipe 10 for use in a passenger compartment heating system of an automotive vehicle. The invention 10 includes a condenser 12, an evaporator, 14 vapor and fluid flow paths 16 and 18 therebetween and a working fluid 20 disposed therein. A thermostat 46 is mounted between the condenser 12 and the evaporator 14 for controlling the flow of fluid 20 therebetween. In a specific embodiment, the condenser 12 is in thermal contact with the engine coolant of the vehicle and the evaporator 14 is in thermal contact with the exhaust of the vehicle. The thermostat 46 is in thermal contact with the engine cooling system and is adapted to block the flow of fluid 20 in the fluid flow path 18 in response to the temperature thereof.

Heat transfer cylinder

Abstract: A heat transfer method and apparatus are disclosed for transferring heat across a cylinder surface, in order to maintain the cylinder surface at a uniform temperature for drying, rolling or otherwise processing a work piece. The apparatus comprises a rotatable cylinder wall with a plurality of heat pipes bent near their evaporator ends and disposed within and around the periphery of the cylinder wall, at least one end wall, and a plurality of hubs interconnecting the cylinder with a drive shaft. The heat transfer cylinder, itself, may comprise a large rotating heat pipe.

Vapor resistant arteries

Abstract: A vapor block resistant liquid artery structure for heat pipes. A solid tube artery with openings is encased in the sintered material of a heat pipe wick. The openings are limited to that side of the artery which is most remote from the heat source. The liquid in the artery can thus exit the artery through the openings and wet the sintered sheath, but vapor generated at the heat source is unlikely to move around the solid wall of the artery and reverse its direction in order to penetrate the artery through the openings. An alternate embodiment uses finer pore size wick material to resist vapor entry.

Method for transferring heat between process liquor streams

Abstract: A method of transferring heat between process liquor streams such as streams of caustic liquor in the Bayer process for producing alumina from bauxite, utilizing a heat pipe arrangement for heat exchange. The process streams respectively pass in contact with one surface of a first heat-exchange wall and one surface of a second heat-exchange wall while being isolated from the second surfaces of the two walls; these second walls are exposed to a closed volume (also isolated from both process streams) containing a heat transfer fluid that vaporizes below the temperature of the hotter process stream and condenses above the temperature of the cooler process stream. The heat transfer fluid vaporizes at the exposed surface of the wall contacted by the hotter stream, and condenses at the exposed surface of the wall contacted by the cooler stream, thereby transferring heat (as heat of vaporization) from the former stream to the latter.

A numerical analysis of the effects of conjugate heat transfer, vapor compressibility, and viscous dissipation in heat pipes

Abstract: The effects of conjugate heat transfer, vapor compressibility, and viscous dissipation in heat pipes are discussed. The accuracy of the partially parabolic versus the elliptic presentation of the governing equations is also examined. The results show that the axial wall conduction has a tendency to make the temperature distribution more uniform for heat pipes with large ratios of pipe wall to effective liquid-wick thermal conductivity. The compressible and incompressible models show very close agreement for the total pressure drop, while the local pressure variations along the heat pipe are quite different for these two models when the radial Reynolds number at the interface is high.

Heat pipe research and development in the Americas

Abstract: The purpose of this paper is to present a review of the recent heat pipe research and development efforts in the Americas. After discussing the research and development of high performance monogroove, tapered artery, trapezoidally grooved, dual-slot, double wall artery, ceramic and other specially designed heat pipes, the transient modeling and testing efforts are reviewed for a variety of heat pipes that also includes variable conductance heat pipes and thermosyphons. The application of heat pipes to terrestrial systems is discussed for the heat recovery systems, Rankine and solar systems, fusion reactor core cooling and the thermal control of electronic equipment. The application of heat pipes to space systems includes the thermal control of space station and satellites, and the radiator design of large space power systems. Although many advances have been made in the past few years in the development of high heat transfer performance heat pipes, the heat pipe modeling efforts are not in step with the technological requirements.

Heat pipe type heat-exchanger for the ventilation

Abstract: A heat pipe type heat-exchanger for ventilation is disclosed, having a plurality of heat pipes affixed with widely spaced fins provided internally in a box like case and arranged horizontally relative to the case, a partition plate dividing the inside of the case into two chambers on the right and left is provided crossing the heat pipes, an inlet and an outlet are formed for the respective chambers of the case, and fans for circulating the air to the respective chambers in opposite directions through the inlets and outlets are provided to make one chamber always an air-supplying chamber and other chamber always an air-discharging chamber. The connection point of power source wires of the fan motors is placed in the air-supplying chamber.

Heat pipe with temperature gradient

Abstract: A heat pipe which maintains a controlled temperature gradient over its length. An annular heat pipe is constructed to have a core area which is a working furnace and to have the heat input at one end and a heat sink at the other end of the annular structure. The core is surrounded by an annular vapor space with a restricted cross section. The reduced vapor space creates a temperature gradient over the length of the furnace, and this gradient is variable and controllable depending upon the quantity of heat being transferred from the heat source to the heat sink.

Concept, design, and use of the photoacoustic heat pipe cell

Abstract: A resonant photoacoustic cell suitable for studies of liquid samples having low vapor pressures has been developed and tested. The cell, the working of which is based on that of the heat pipe, is of a simple, compact design; its operational temperature range is limited only by the choice of working fluid and the material used to construct the cell. The feasibility of this novel‐type cell has been demonstrated by obtaining the absorption spectrum of geraniol C10H18O at 403 K in the spectral region covered by the CO2 laser emission.

Air conditioner for a vehicle

Abstract: At least two blowoff duct which discharge conditioning air into a car interior have separate individual channels. At least one of the blowoff ducts is a main duct which communicates with a heating device or a cooling device, and the remaining ducts are auxiliary ducts. A heat conductor is arranged in each blowoff duct and the heat conductors are connected conductively by a heat pipe. Heat energy of the conditioning air in the main duct which was heated by the heating device or cooled by the cooling device is transmitted to conditioning air in the auxiliary duct by the heat pipe and heat conductors so as to heat or cool the air in the auxiliary duct. The heat pipe may be made to be rotatable by a driving device, and a heat conductor in the auxiliary duct is a blowing fan. Air conditioning to the area surrounding a rear seat is achieved by arranging a heat pipe between right and front seats in the car interior and by forming a heat conductor at the rear end of the blowing fan.

Shell and tube heat pipe condenser

Abstract: An improved conduit assembly for coupling a heat pipe evaporator with a Stirling engine heat exchanger. The conduit assembly features a cylindrical main tube section connected to a flared shell joining the heat exchanger of the Stirling engine. The flared shell provides an increasing cross-sectional area which reduces the velocity of vaporized heat pipe working fluid flowing from the heat pipe evaporator to the heat exchanger. Such reduced velocity has been found to minimize entrainment of liquid within the transmitted vapor. The conduit assembly further includes an internal small diameter liquid return duct which provides additional isolation of the liquid and vapor phases of the heat pipe working fluid as a means of further reducing entrainment. Surface tension breakers are provided which communicate the heat exchanger to the inlet end of the liquid return duct to wick away liquid working fluid from the heat exchanger. Contaminant gases within the heat pipe are removed through the use of an externally heated getter and an internal getter within the vapor flow path.

A Dimensionless Number for the Contact Line Evaporative Heat Sink

Abstract: The main driving force for flow in very thin films can be the gradient in the van der Waals force. This phenomenon was used by Wayner et al. (1976) to develop an equation for the interline heat transfer coefficient of an evaporating wetting film. Buried in this development is a dimensionless group that can enhance, when properly viewed, the understanding of the evaporation process in the contact line region where the film thickness becomes vanishingly thin. This process is crucial in systems that rely on heat transfer in ultrathin films such as evaporating drops on solid surfaces and evaporating menisci in heat pipes. Herein, the authors discuss the significance and use of this dimensionless contact line heat sink number.

Numerical and analytical solutions for two-dimensional gas distribution in gas-loaded heat pipes

Abstract: This work presents a two-dimensional axisymmetric diffusion model for the noncondensable gas distribution in gas-loaded heat pipes and thermosyphons. The new model, based on an integral analysis, has major advantages over existing, computationally time consuming, two-dimensional models. It has equal accuracy while using only the computational effort required for the cruder one-dimensional model, and also includes the effects of wall conduction and spatial variation of the condenser heat transfer coefficient. To simplify design calculations further an analytic two-dimensional solution is established, which gives excellent results over a wide range of parameters.

Cooling pond enhancement

Abstract: An improvement to a cooling pond is disclosed which utilizes metallic heat pipes to transmit heat from the cooling pond to the ambient air environment.

Leading edge heat pipe arrangement

Abstract: Heat pipe (10) includes an acute angle leading wedge shape form (38) with a radiused leading edge (26). Engine fuel supply (65) cools the trailing wedge shape form (40). The intense heat flux at the leading edge is cleanly dissipated and spread over substantial heat pipe cooling surface (64, 66). A coating (36) on the external surface of the leading edge wedge shape form is formed of a layer of iridium and a layer of oxide.

Spherical solar energy collector

Abstract: A solar collector particularly for receiving concentrated solar energy from a large parabolic reflector and which forms the evaporator of a heat pipe type heat transfer mechanism. The solar collector is formed from a pair of spherical shell portions which are joined at their perimeters such that they are nearly tangent at their joint. This configuration provides low mechanical stresses on the welded joint, making the structure resistant to creep failure. The inside surfaces of the solar collector are preferably covered with wire screens for the transport of liquid heat pipe working fluid. Various finenesses of mesh can be used. Preferably, a coarse mesh is in intimate contact with the inside surfaces of the collector to act as a transport medium with a finer mesh covering it. These mesh layers can be applied to surfaces of sheet metal blanks through sintering or other processes which are thereafter deformed to the desired shell configurations.

Self-heated diffuser assembly for a heat pipe

Abstract: A diffuser unit for allowing non-condensing gases collecting within a heat pipe to be eliminated. The embodiments described herein define a cavity for collection of non-condensing gases such as hydrogen. The housings are arranged such that the heat pipe working fluid in vapor form transfers heat to the walls of the housing defining the collection cavity to raise the wall temperature thus increasing its permeability to the non-condensing gas. Accordingly, when the heat pipe is used in applications where non-condensing gases such as hydrogen tend to diffuse into the heat pipe such as when it is directly heated by a hydrocarbon combustion, such non-condensing gases can be readily eliminated. Such diffusion of non-condensing gases occurs without the requirement of providing a conventional "getter" which uses special material for absorbing or breaking down such non-condensing gases. The diffuser assemblies in accordance with this invention are self-regulating and entirely passive in operation, requiring no external heat inputs or control signals.