Showing papers on "Heat sink published in 1973"

Reflector lamp cooling and containing assemblies

Abstract: A cooling assembly particularly suitable for use with high brightness light sources requiring compact housing. The assembly comprises an air cooled heat sink and a connecting means being flexible and having a high thermal conductivity coefficient. This device provides an efficient method for cooling filament leads in the seal end of high brightness lamps and the joint between the lamp and reflector, thereby increasing lamp life.

Ultraviolet lamp housing

Abstract: An ultraviolet lamp housing has side and end walls defining a relatively elongated lamp enclosure having an elongated opening at one side, in the operative position of the housing. An elongated ultraviolet lamp is mounted between the end walls. A pair of elliptical reflector sections are mounted in the enclosure for rotation about axes extending in spaced parallel relation to the lamp. The reflector sections have a first closed position in which they form an elliptical reflector having a first focus at the lamp and a second focus at the plane of the opening, and have a second closed position in which they are interposed between the lamp and the opening. The side of the lamp enclosure opposite to the opening is formed with a coolant duct and a heat sink is mounted in this duct and displaceable coordinate with the reflector sections. In the first closed position of the reflector sections, the heat sink is disposed in spaced relation to the closed reflector sections and toward the outer side of the coolant duct. In the second closed position of the reflector sections, the heat sink is moved inwardly to form an inner wall of the coolant duct. In another embodiment of the invention, the heat sink may be stationary and form the inner wall of the duct and, in this case, conduits for the flow of liquid coolant are superposed on the heat sink for extracting the heat of the lamp enclosure.

Heat flow to the workpiece from a TIG welding arc

Abstract: Less than half of the heat generated in a TIG welding arc (typically 1600 W at 16 V, 100 A) is transferred to the workpiece (anode). Convection, conduction and radiation from the gas occur over the whole of the arc region, but they represent relatively minor contributions to the total heat balance. The principal anode heating and cooling mechanisms involve electron and space-charge effects at the surface. These electron effects are evident in the workfunction (typically 45 V) which is dominant, the electron thermal energy transfer (1 V) and the anode fall (2 V), and they are concentrated in the restricted anode current spot so they may be considered as a localized heat source. Evaporation is most intense from the anode spot region and carries away some heat. However, most of the vapour condenses on the cooler, outer regions of the anode surface covered by the arc. In this way, heat is redistributed and diffused over a wider area. Vaporization effects explain the differences between previous measurements with cooled copper anodes (in which 80% of the arc power is transferred to the metal) and ones with practical, molten-steel welds (less than 50% heat transfer).

Semiconductor mounting devices made by soldering flat surfaces to each other

Abstract: A flat surface of a semiconductor chip is soldered to a relatively larger flat surface of a heat sink by forming a plurality of closely spaced grooves in the flat surface of the heat sink, coating the flat surfaces of the chip and the heat sink with nickel, disposing solder between the coated surfaces of the chip and the heat sink, and heating the surfaces until the solder melts. The grooves in the heat sink prevent the entrapment of gas bubbles between the chip and the heat sink, thereby providing good thermal conductivity and a relatively low electrical resistance between the chip and the heat sink.

Arrangement to control heat flow between a member and its environment

Abstract: An arrangement of insulating, thermal absorbing and/or dissipating elements controlling heat flow between a member and its environment. In certain permafrost environments, for example, one or more elements of the system can include a heat sink and/or a thermal bleed where the member is heated. The arrangement controls heat flow from a heated member at such a rate that the total heat transfer does not exceed the limits of the residual heat capacity of permafrost below the freezing point thereof during cyclic climatic influences. The arrangement takes advantage of the fact that artificial heat from the heated member can be controlled, while natural solar heat is balanced by the seasons. The elements also serve to maintain relatively stable temperature differentials between heated or cryogenic materials and their adjacent ground support, so there is a minimal effect of one on the other.

Energy recovery and conversion system

Abstract: A heat energy recovery system for extracting heat from earth cavities in which a heat exchanger is placed in a cavity and coupled in a closed loop heat exchange arrangement with an above ground heat exchanger Particular use is made of the liquid head in a pipe going down to the heat exchanger in the cavity to create substantial pressure to operate an expansion valve at the lower heat exchanger where evaporation occurs to enhance heat exchange This system also discloses new arrangements of fluid energy division and temperature amplification to enhance operation of the system

Semiconductor device enclosure and method of making same

Abstract: An economical power transistor housing and method for making it. The housing base member is of a reinforced plastic with a unique circuit pattern on it. A metal heat sink member nests in an aperture in the base member and connects with the circuit pattern. The heat sink has orientation means. A semiconductor device die with mutually parallel wire bond contact pads is affixed to the heat sink member in a predetermined manner. Terminal pins extend through the base member and connect with uniquely configured discrete portions of the circuit pattern. These portions have elongated mutually parallel wire bonding areas oriented perpendicular to the contact pads on the die. A cup-shaped cover encloses the die and associated wire bonds on the board. The structure permits automated assembly, soldering and wire bonding, and includes the manufacture of subassemblies for testing prior to device completion.

Transistor design and thermal stability

Abstract: A model has been developed for the computation of forward second breakdown due to lateral thermal instability in power transistors. The method of analysis is to derive the steady-state current density and temperature distribution of a given transistor design under specified operating conditions, and then to calculate the response of the device to a temperature impulse suddenly applied internally. The current flow calculations have been carried out by using a distributed transistor model, and for the time-dependent heat flow problem the finite difference approach was used. The effect of device design parameters such as chip thickness, base width, emitter width, base impurity concentration, etc., on the thermal stability has been calculated. Also, the effect on transistor stability of the current and voltage operating point, as well as the heat sink temperature, has been analyzed. Information on the stability of a power transistor under pulsed condition is derived by calculating the time constant for thermal runaway. The results of this analysis indicate that the delay time is of the order of 1 ms.

Heats of mixing of binary mixtures of N-methylpyrrolidinone, ethanolamine, n-heptane, cyclohexane, and benzene by differential flow calorimetry

Abstract: The heat produced by mixing two continuous liquid flows is measured in a mixing cell consisting of a T tubing where the two incoming streams merge and a long narrow channel where the mixture exchanges heat with an isothermal air bath through an electric heat-flux meter. The liquid flow rates are set to allow the liquid to reach the bath temperature before leaving the mixing cell. The incoming liquids are brought to the bath temperature through a heat exchanger. Viscous flow heat evolution is reproduced by circulating the liquid in a reference cell. The corresponding heat effect is subtracted from the heat effect in the mixing cell. Both cells are provided with calibration heaters. The heat flux detector consists of a thermocouple assembly soldered to the cell and a heat sink kept at the bath temperature. The electric power is linearly related to the heat flux transmitted to the heat sink. The electric signal is amplified by a Keithley 150 B amplifier and recorded. The measurement is obtained by comparing the base line shift of the recorder on mixing to the deviation produced by a known current applied in one calibration heater while the liquids are pumped. The calibration cell is chosen to reduce the base line shift on mixing, and the current is set to produce a heat effect close to that of mixing. Tacussel “electroburap” BC/VRE Syringe pumps, equipped with lO-cm3 syringes were set at flow rates ranging from 0.01 to 0.4 cm3/min. Flow rates were obtained with a precision of 0.2% and calibrated by weighing. The use of a step-by-step electric motor did not produce any fluctuation of the recorder response. Degassing of pure liquids was found necessary because the solubility of air is lower in mixtures than in pure-liquids. Bubble growth in the mixing cell caused instability of the recorder response. Air concentration

Equipment for exhaust gas detoxification in internal combustion engines

Abstract: An insulated heat pipe is provided which transfers heat from the engine's exhaust manifold to an exhaust gas reactor. The heat pipe contains a first zone serving as an evaporation zone, a second zone serving as a transport zone for transporting a working medium between the first zone and a third zone. The third zone serves as a condensation zone. The heat pipe has an interior capillary tube along which the condensed heat transfer medium flows toward the heat source and within which the vaporized medium flows toward the heat sink.

Method for directional solidification

Abstract: Method and apparatus for improving the prodution rate of directionally solidified castings employing an annular mold having one or more molding cavities therein and a pair of heat radiating elements disposed concentrically with the mold, one being located inside and the other being located outside the mold, the heat radiating elements being arranged so that no temperature gradient exists across the mold. A pair of heat sinks is provided, the heat sinks being coaxial with the two heat radiating elements. Means are provided for causing relative movement between the annular mold and the heat radiating elements and the coaxially aligned heat sinks. The annular mold is positioned on a highly heat conductive pedestal or chill. The mold is preheated by the heat radiating elements to a temperature above the solidification temperature of the metal to be cast. After casting, the solidification of the metal progresses upwardly from the chill and the relative movement between the annular mold and the heat radiator-heat sink combination causes the solidification innerface to occur at or near the boundary between the heat radiators and the heat sinks. A baffle is advantageously positioned at this boundary to prevent heat being radiated from the heat radiators to the heat sinks. The solidified metal in passing through the heat sinks radiates heat uniformly to the heat sinks so as to prevent a lateral or radial thermal gradient across the mold during solidification of the metal therein.

The heat pipe

Abstract: The heat pipe is a device having a high thermal conductance which utilizes the transport of a vapour and rejection of latent heat to achieve efficient thermal energy transport. The theory of heat pipes is well developed. Their use in applications involving temperatures in the cryogenic regime, and with development units running as high as 2000 degrees C, shows that they can function over a large part of the temperature spectrum. Applications in spacecraft, electronics and die casting are but few of the uses for these devices

Pipe heat transfer assembly and method of making same

Abstract: Pipe heat transfer assembly and method of making same, wherein a strip of heat transfer material is pre-shaped to a solid flexible form for closely .[.comforming.]. .Iadd.conforming .Iaddend.with a heat transfer element for either heating or cooling and which is also pre-shaped to fit closely within an external channel member, whereby the entire assembly may be more easily and rapidly installed with unskilled labor in the field on a pipe to be heated or cooled, using retaining band means as the holding means for the assembly, with the assurance of complete coverage of the heat transfer element by said heat transfer material so as to eliminate air gaps. The heat transfer material may be pre-shaped by molding or extruding, with the heat transfer element embedded therein during such pre-shaping, or with a preformed space for the heat transfer element. The heat transfer material is solid, capable of retaining its shape, and remains flexible, after pre-shaping, within the normal temperature range to which the material is subjected, preferably within a range of from about 10° F. to about 120° F.

Method of making thermal attachment to porous metal surfaces

Abstract: Thermal conduction between a heat source (such as a transistor) and a porous metal heat sink is optimized by providing a unique interface mounting pad of high thermal conductivity metal. Pad is built up by flame spraying molten metal particles of copper onto porous metal surface. High thermal conductivity is assured by nature of the process which fills the porosity voids providing a dense supplemental thermal path from transistor mounting pad to sub-layers of laminate. The particle bonding is done at high temperature and is distinguished from such established surface bonding techniques as spraying liquid metallic dispersion or soft solders etc.

Heat pipe interfaces

Abstract: An interface for interconnecting heat pipes is disclosed. The interface is itself a special purpose heat pipe adapted to efficiently transfer heat from the condenser of a first heat pipe to the evaporator of a second heat pipe. Using the present invention, simple heat pipes can be interconnected to form a complex heat pipe structure for particular applications.

High frequency diode having simultaneously formed high strength bonds with respect to a diamond heat sink and said diode

Abstract: High frequency diodes are manufactured by methods forming an efficient heat path from the active diode junction through a diamond heat conducting member to a heat sink. A planar preformed element which becomes a permanent part of the diode structure is used to transfer the forces which form the bond between the diamond heat conducting member and the heat sink; simultaneously, the preformed element is bonded to an opposite side of the diamond, becoming a permanent part of the high frequency circuit of the diode.

Integral reflecting cavity semiconductor pumped laser

Abstract: The laser rod which may be Nd:YAG is reflectively coated over all of its surfaces except the ends and a narrow strip extending along the surface of the rod and parallel to its axis. An array of light emitting diodes of either non-coherent (spontaneous) light emitting type or coherent (laser) light emitting type are disposed with the light emitting direction being through the narrow strip. A metallic heat sink completely surrounds the sides of the laser rod except for the elongated strip, and is in good thermal conducting relation with the rod. A metallic heat sink is in good heat conducting relation with the light emitting diodes and is separated by an insulating spacer from the laser rod heat sink. The light emitting diodes are in a chamber defined by the laser rod, the heat sinks, and the insulating spacer. The chamber may or may not be filled with a clear optical cement.

Heat resistant laminate

Abstract: A heat resistant laminate suitable for kitchen countertop surfaces which comprises a top layer of a flexible, transparent polymeric sheet having a high heat resistance, a second layer of a flexible, hard surfaced material, a third layer of a flexible metal foil heat sink, a fourth layer of a pressure sensitive adhesive and a bottom layer of a sheet of release material.

Method of assembling an electric motor device and heat sink

Abstract: An electric motor housing and heat sink, and the method of assembling the same, in which a housing, constructed of electrically insulating material subject to thermal distortion, includes integral means for orienting and securing a metal heat sink therein, the latter having passages through which cooling air is drawn. The orienting means comprises deformable or meltable means such as pins integral with the housing and adapted to extend through apertures in the heat sink. The method includes assembling and retaining the heat sink into an operative integral position in the housing by deforming, for example, melting the interfitted housing pins into retaining relation against the heat sink. In addition, a shaft bearing may either be preassembled in the heat sink before assembly to the housing, or the heat sink bored and the bearing inserted therein after the heat sink is assembled to the housing.

Cooling arrangement for a direct current power supply

Abstract: Apparatus and method for dissipating the heat generated by the components of a power supply. The components can be isolated from one another in a plurality of sealed compartments. Each isolated component can be thermally connected to a heat pipe which is operative to transfer heat generated by the respective component out of its sealed compartment to a heat sink which is in communication with ambient air currents.

Improved thermally conductive and electrically insulative mounting systems for heat sinks

Abstract: A two-part adhesive system for mounting heat sinks to power supply cases. A heat sink made of some suitable material such as aluminum is provided having holes or slots for mounting semiconductors thereon. At least part of the heat sink is coated with a material which exhibits high thermal conductivity and high electrical insulating strength. The heat sink is adhered to the power supply case by an epoxy formulated adhesive material having granules placed therein for electrical spacing. The adhesive material also has high electrical insulating strength and high thermal conductivity. The adhesive material also forms a good mechanical bond.

Radiative heat transfer in furnaces: Further development of the zone method of analysis

Abstract: Further development and testing of the zone method of analysis is described. In the zone method, the temperature and heat-flux distributions in a furnace are obtained by dividing the system into zones, and solving simultaneously energy balances on each zone. The present state of development of the method is discussed, and avenues for further development are considered. A method of including the effect of luminous radiation is described. For this the emissivity ofa cloud of soot particles is represented as the weighted sum of grey gases. It is also shown that the emissivity of a gas-soot mixture can be represented as the weighted sum of grey gases. The validity of this emissivity equation is examined by comparing calculated and measured distributions of radiation intensity through a luminous flame. Good agreement between calculated and measured traverses is found. With luminous flames, large variations in gas-absorption coefficient occur in furnaces.Methods of allowing for variations of gas-absorption coefficient when evaluating radiative “exchange areas” are discussed, and an approximate method is presented. A method of allowing for different types of heat sink in a surface zone is described. Themethod allows for the replacement of the composite surface with an equivalent grey surface having an effective emissivity and temperature. Also, surface energy factors are derived which enable the radiant energy at a surface to be divided in terms of the amount of heat absorbed by each type of sink in the zone. Experimental testing of the zone method of analysis is described. The zone method incorporatingthe abovementioned improvements was used to predict temperature and heat-flux distributions in the IJmuiden furnace. The initial conditions of flow pattern, heat release, and absorption coefficient were obtained from the experimentally measured properties in the furnace. The predictions were compared with measured values of gas temperature and surface heat flux, and good agreement was found. It is concluded from the agreement shown, that the zone method of analysis is a realisticmathematical model which can be used with some confidence for the calculation of heat transfer in furnaces.

Rectifier heat sink plates with alternate supporting tabs

Abstract: The heat sink plates on which the main current diodes are mounted have the shape of annular discs with outwardly extending tabs bent up at right angles with circumferential spacing between them sufficient for interfitting the tabs of the two heat sinks when they are superimposed with just enough spacing for insulation from each other. The main current diodes are mounted on the flat portions of the tabs and their free connection leads are connected to connection plates on a circuit connecting support plate, held in position on the upturned part of the tabs of the heat sinks, forming a sort of lid to the pot-shaped assembly and carrying clips for connections to the windings of the generator. There is a cut-out sector of the annular disc assembly to accommodate a brush, regulator, or both. Exciter diodes are mounted on the connection support plate with anodes connected to a metal strip extending around the inner circumference of the central hole of the annular disc and connection support plate, with its end extending for connection to the regulator or brush in the cut-out sector.

Two fluid solar boiler

Abstract: A boiler for powering fluid pressure motors. The rays from the sun are focused by a lens through a transparent oil primary heat transfer medium and onto a heat absorber. The heat directly absorbed by the oil and by contact with the heat absorber is circulated by a thermo-siphon through a heat exchanger. The heat exchanger transfers heat and raises the temperature of a hydrocarbon fluid utilized as the secondary heat exchange medium. The expanded hydrocarbon powers a fluid pressure operated motor and is returned from the low pressure side of the motor to condensers after which it is compressed and returned to the heat exchanger in a closed cycle operation.

Heat dissipation for power integrated circuit devices

Abstract: An integrated circuit chip having circuit elements capable of relatively high power operation is encapsulated in a body of polymeric material having the form of an elongated prism. Conductors are electrically coupled to the circuit elements in the chip and extend outwardly of the body through a relatively long side thereof. A heat conducting stud is anchored in the body and is thermally coupled to the chip. The stud extends outwardly of the package through another of its relatively long sides. A heat sink may be coupled to the stud outside of the package.

Structural heat pipe

Abstract: A combined structural reinforcing element and heat transfer member is disclosed for placement between a structural wall of a container or housing which is to be thermally protected and an outer insulation blanket disposed thereover and spaced apart therefrom. The element comprises a heat pipe, one side of which supports the outer insulation blanket, the opposite side of which is connected to the structural wall. Heat penetrating through the outer insulation blanket directly reaches the heat pipe and is drawn off, thereby reducing thermal gradients in the structural wall. The element, due to its attachment to the structural wall, further functions as a reinforcing member therefor.

Heat pipe turbo generator

Abstract: The adaptation of a heat pipe as a turbo-generator or other power output device for a reliable, quiet, light-weight high-endurance power source is shown. The device requires input thermal energy from a burner radioisotope (or solar heat) and also forced or natural heat rejection from condenser surfaces. Thermal energy conversion to a suitable power output is accomplished by encapsulating a turbine wheel within a heat pipe shell, located in an appropriately geometrical contoured section. Flow work extracted from the kinetic energy of the vapor flow provides rotary shaft power output. The shaft power can drive an electrical generator, pump, compressor, or similar device, also mounted within the heat pipe shell structure. A completely self-contained enclosed unit is provided which requires only external power connection at attachment terminals.

Power generation from hot brines

Abstract: Hot fluid which may contain salts and other dissolved minerals is passed through a direct contact heat exchanger in heat exchange relationship with a heating fluid that has a specific gravity sufficiently below the specific gravity of the hot fluid that it may pass from the bottom to the top of the heat exchanger chamber in contact with the hot fluid. The pressure of the chamber is maintained above the vapor pressure of the hot fluid at the entering temperature of the fluid. The heat transfer fluid is selected so that the salts and other minerals in the fluid are insoluble in the heated heat transfer fluid. The heated heat transfer fluid is passed in heat exchange relationship with a working fluid that is vaporized in the heat exchangers and is subsequently passed through a power extracting gas expansion device. Alternatively, an oily substance is added to the hot fluid which may contain salts and other dissolved minerals, and the composition is passed through one or more surface contact heat exchangers for heating a a working fluid. The oily substance coats the surface of the exchangers to prevent any mineral deposition.