Oct. 15, 1968
`
`S. OKAY
`
`MULTI-LIQUID HEAT TRANSFER
`
`Filed June 7, 1966
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`3,406,244
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`
`FG
`3
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`NVENTOR
`SEWGN OKTAY
`
`AT TORNEY
`
`Immersion Systems LLC – Ex. 1009
`PGR 2021-00104 (U.S. 10,820,446 B2)
`1 of 4
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`United States Patent Office
`
`3,406,244
`Patented Oct. 15, 1968
`
`3,406,244
`MULTI-LIQUID HEAT TRANSFER
`Sevgin Oktay, Beacon, N.Y., assignor to International
`Business Machines Corporation, Armonk, N.Y., a cor
`poration of New York
`Filed June 7, 1966, Ser. No. 555,730
`7 Claims. (C. 174-15)
`
`ABSTRACT OF THE DISCLOSURE
`A cooling system is provided for cooling heat gener
`ating electronic components which are completely im
`mersed in a liquid having a low temperature boiling point.
`This dielectric liquid, such as a fluorcarbon, preferably
`boils only somewhat above ambient room temperature at
`atmospheric pressure. A second liquid having a lower
`density and a higher boiling point than the first mentioned
`liquid is superimposed on the first liquid resulting in an
`interface between the two liquids where nucleate boiling
`20
`bubbles generated in the first fluid are principally con
`densed. The superimposed liquid is maintained at a pre
`determined temperature by means of a cooling arrange
`ment.
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`O
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`memory array and a second liquid is superimposed on
`the free surface of the first liquid. The first liquid prefer
`ably boils at atmospheric pressure only somewhat above
`ambient room temperature. When the first liquid is thus
`heated, bubbles are formed and condensed principally at
`least at the interface of the two liquids. This is achieved
`by proper correlation in the selection of liquids, their
`volumes, their interface surfaces, and the rate of heat
`generation. Preferably, the superimposed liquid is main
`tained at a predetermined temperature. The disclosed sys
`tem is constructed to operate at ambient temperatures and
`pressures and has an external system for cooling the con
`denser liquid which preferably is water or a silicate ester.
`The boiling liquid preferably is a dielectric liquid, such
`as perfluorodimethyl cyclobutane.
`The realization of the above objects and others, along
`with the advantages and features of the invention, will be
`apparent from the following description and the accom
`panying drawing in which:
`FIG. 1 is a broken-away perspective view of a computer
`memory array mounted in a container and illustrates how
`a liquid contacting the heat-generating array forms bub
`bles which are condensed by a superimposed liquid;
`FIG. 2 is a partially-schematic, cross-sectional showing
`of another embodiment and shows the generation of
`bubbles, their condensation and return to the interface;
`and
`FIG. 3 is a schemtaic showing of the use of three liquids
`providing multilocation condensation of vapors from the
`lowest liquid.
`In FIG. 1, a liquid-tight container 11 has a slip-on
`cover 13 and a memory array 15 located therein which is
`electrically connected through a wall 17 of the container.
`The wall 17 has a rectangular opening (not appearing)
`which has an atmospheric sealing gasket 19. A memory
`array mounting block 21 is attached by screws 23 to the
`container within the periphery of the rubber gasket 19.
`Liquid-sealed block 21 has outwardly projecting pins 25
`for electrically connecting the memory array to conven
`tional memory drive, sense and other means. The array
`15 has a plurality of memory planes 31 which include a
`frame 33, ferrite cores 35 and wires 37 passing through the
`doughnut-shaped cores.
`The array 15 is immersed in a first liquid 41 (such
`as the above mentioned fluorocarbon) which boils at about
`113 F.5 F. under atmospheric pressures (for example,
`12.0 to 16.0 p.s.i.a.). A second liquid 43 having a relative
`ly higher-boiling-point temperature is superimposed on the
`free surface of the first liquid so that an interface 45 is
`formed. Three sets of bubbles 46, 47 and 48 are shown.
`The middle set 47 shows the preferred method since the
`bubbles are condensed at the interface 45 due to the cor
`relation of liquid selection, the interface area, the boiling
`point temperatures, the heat absorption rates, the ambient
`temperature and pressure, the volumes of the liquids, and
`the maximum rate of heat generation from the directly
`contacted cores, wires, and frame connections. The left
`set of bubbles 46 shows the second method wherein es
`sentially all bubbles are condensed at the interface and
`within the second liquid. The right set of bubbles 48
`show the foregoing condensation plus condensation at the
`surface of the second liquid. These modes will be further
`explained.
`The means for cooling the upper, condensing liquid 43
`includes an outlet pipe 51 and an inlet pipe 52, both ex
`tending through a side wall of the container 11. The out
`let pipe has a make-up funnel 53 and connects to a stor
`age tank 54. A pump 55 having motor 56 receives liquid
`from the tank and pumps it through a cooling coil 57,
`which has fan 58 for cooling, to a thermostatically con
`trolled valve 59. The temperature sensor 60 for the valve
`is mounted near the top of the memory array 15. The
`
`This invention relates to heat transfer and more par
`ticularly concerns methods and means for cooling a heated
`element, such as an electronic element, by heat exchange
`with a liquid to give boiling action.
`In the prior art, it has been proposed to cool electric
`devices or components by direct heat exchange with a
`liquified refrigerant. The Greene patent (No. 2,643,282)
`proposes immersing a radio chassis in a liquified refriger
`ant and then conventionally condensing externally by
`means of a compressor and condensing coil. The Whitman
`patent (No. 2,774,807) teaches a similar arrangement for
`a transformer and proposes to condense “Freons' and
`fluorcarbons by radiator tubes and a noncondensable gas,
`such as sulphur hexafluoride. The Goltsos patent (No.
`3,204,298) proposes an evaporative-gravity cooling ar
`40
`rangement in which vaporated liquid, such as FC-75 (3M
`trade designation for CFO), is condensed by a cold
`plate. These and other prior art proposals have disadvan
`tages. For example, in electronic solid-state computer ap
`plications, it is not desired to operate with a high pressure
`45
`cooling system since lead sealing, general leakage and
`non-accessibility present problems and undesired arrange
`ments. Another disadvantage resides in a poor heat trans
`fer rate among "percolated' bubbles and the heat extrac
`tion means especially where an external compressor is not
`used.
`An object of the present invention is to ovrcome these
`problems and disadvantages by providing novel means for
`condensing bubbles of a liquid refrigerant which is heated
`by an element, such as ferrite-core, memory arrays of
`a computer.
`Another object is to provide a new, improved method
`for efficient heat transfer in which heat-generated vapors
`of a liquid contacting a heated element are condensed
`without typical compression or indirect heat exchange.
`A further object is the provision of a novel heat trans
`fer method and means in which nucleating vapors from a
`boiling liquid are directly condensed by a superimposed
`liquid or liquids.
`An additional object is the provision of a heat transfer
`65
`method and apparatus which is especially useful for cool
`ing electronic devices, such as computer parts, since am
`bient pressures and near-ambient temperatures are used
`whereby leakage is avoided and accessibility for change
`is possible.
`In accordance with a disclosed embodiment of the in
`vention, a first liquid is in direct contact with a computer
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`Immersion Systems LLC – Ex. 1009
`PGR 2021-00104 (U.S. 10,820,446 B2)
`2 of 4
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`25
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`3,406,244
`4.
`3.
`tem results. The overflowing liquid is selected to have a
`bellows valve operator 61 also operates the pump motor
`large heat absorbing capacity.
`56 via a switch (not shown). Valve 59 connects to inlet
`As above mentioned, the condenser liquid preferably is
`pipe 52. A thermocouple temperature control is alternately
`water or silicate ester. The surface tension values of these
`useful.
`5 two liquids are respectively (in dynes per centimeter) 25
`This arrangement has the advantage of remotely locat
`and 72. Thus, the bubbles in silicate ester are smaller. The
`ing the heat dissipating means so that the computer area is
`preferred boiling liquids in order are perfluorodimethyl
`not burdened. Since temperature controlled well or river
`cyclobutane (as supplied by Du Pont) or the fluorcarbon
`water could be used in some situations, it is apparent that
`liquid which is marketed by Minnesota Mining and Manu
`a flow-through system can be used. Further, it is apparent
`facturing and designated as FC 78 (B.P.122--10 F).
`that an inexpensive, readily-evaporated inert liquified gas
`The condenser liquid is essentially immiscible in the heat
`can be added at a regulated rate through funnel 53 and
`absorbing boiling liquid. The aforementioned sodium and
`released through top vent 63. Also, it is contemplated that
`potassium metal system has an interface since the boiling
`indirect cooling of the top liquid be done by a circulating
`liquid is saturated (the condenser molten material being
`or evaporative coil 65 which has a conventional cooling
`5 in a quantity which exceeds the solubility). It is also
`section 66 including compressor 67, condenser 68 and
`feasible to use liquid sodium and an inert liquid which has
`temperature responsive valve 69.
`a higher specific gravity and a lower boiling point. For
`It is apparent that other heat-absorbing, low-boiling liq
`example, in space re-entry or deep-sea activities, the tem
`uids are useful, such as chlorinated fluorcarbons generally
`peratures and/or the pressures will provide an environ
`known as Freons (Reg. TM-Du Pont). When the elec
`20 ment for the present heat transfer method using liquid
`tric devices (memories, circuit modules for logic, etc., and
`power supplies) are suitably insulated, non-dielectric liq
`Sodium, wherein a heat flux moves from a heavier molten
`material to an interface formed with a lighter liquid-like
`uids are used. Mercury is suitable when the heat generating
`material so that gas-like formations are condensed princi
`rate is sufficient as found in transformer or nuclear reactor
`installations. The condenser liquid, of course, is essentially
`pally at the interface.
`immiscible in the heat absorbing liquid, is lighter in weight,
`In FIG. 2, the evolution of gas-like formations or
`"bubbles” is again more-or-less schematically illustrated
`and has an appreciably higher boiling point than the boil
`ing liquid. For example, with mercury as the boiling liquid,
`in enlarged fashion. Thus, the intermediate set of bubbles
`suggests the generation of bubbles and the condensation
`polyphenyls (page 172, Heat Transfer Media, 1962, Rein
`thereof at the interface of the liquids. This is the pre
`hold) or liquid nitrogen is used. It is also desirable to use
`liquid potassium and the lighter liquid potassium-sodium
`30 ferred mode since it gives the maximum heat transfer
`rate with the least operating complications. When a small
`when nuclear reactor conditions (such as found in sub
`bubble arrives at the interface, it floats temporarily and
`marines) are encountered.
`then, due to pressures and contact with the condensing
`Referring to FIG. 2, the container 73 has condenser
`liquid, condenses to liquid or sometimes implodes (col
`liquid 75 and boiling liquid 77 in which is immersed an
`35 lapses in an internal direction). The disintegration of the
`electronic module or other heat generating device 79. It
`is apparent that the device could transmit heat through
`floating bubbles gives very small bubbles which also "ride'
`the bottom container wall, for example, by conduction.
`the interface giving maximum heat transfer (maximum
`Two connecting wires or leads 81 and 83 extend from the
`bubble surfaces to the condensing boundaries of the con
`module 79 through the liquid 77 through a side wall to
`denser liquid). The various factors (such as heat influx)
`40 are correlated to give this preferred mode whereby the
`the exterior of the copper-wall container 73 and the
`small bubbles or generated gas-like formations are princi
`surrounding enclosure 85. These wires are insulated if the
`lower liquid is not dielectric. The coating on the module
`pally condensed at the interface. The bubbles, in some
`is such as to give protection to the module, if the boiling
`instances, are "divided' as to mode of condensation. De
`liquid is not dielectric. A cooling coil 87 is positioned
`pendent upon the heat input rate, small bubbles move
`in the condensing liquid to adequately remove the heat
`45 horizontally to form large bubbles. The large bubbles
`absorbed in condensing. As mentioned, the modes of con
`are formed by the merging of small bubbles until suffi
`densing the vapor bubbles at, and above, the two-liquid
`cient buoyancy develops to give a raise from the interface.
`interface 89 will be further described as observed in opera
`Thus, the just-described mode combines with condensation
`tions in which heat input was gradually increased. The
`of large bubbles in the body of the condenser liquid as
`cooling coil 87 is a secondary means for removing heat in
`50 when heat input is increased. By both these modes, con
`this embodiment. Inner rectangular container 73 has a
`densation is essentially completed by contact with the
`plurality of overflow orifices 91 at the level of the con
`upper liquid. Of course, a small number of large bubbles
`densing liquid so that warm liquid continuously overflows
`might pass up to the surface of the condenser liquid. At
`and dribbles down the "wetting' surfaces of the copper
`the condenser liquid surface, condensation is effectively
`walls. A pool of liquid 93 collects, above the bottom wall
`55 complete since essentially all of the large bubbles reach
`of enclosure 85. This pool 93 is maintained at a predeter
`ing this surface are condensed at this surface. With a
`mined level by a suitably-controlled pump 97 which draws
`further increase in heat input, the second mode predomi
`the liquid through heat exchanger 99. The heat exchanger
`nates. An insignificant number of bubbles might break
`dissipates the heat at a remote location or has cooling
`through this surface to the space above. In the preferred
`liquid flowing therethrough to waste. Pump 97 discharges
`60 mode, this is a rarity. In some applications--as where the
`the cooled liquid to pipe 101 which distributes the cooled
`space for the two liquids is at a minimum-the heat input
`liquid adjacent the interface 89. The arrows suggest how
`rate is selected to deliberately give vapor escape so that
`the return liquid is sprayed to the location of the inter
`remotely-located heat dissipation with pressurizing and
`face so that bubbles are condensed at an early stage.
`condensation can be done. For example, FIG. 1 outlet
`The two containers are closed off by a single cover 103.
`65 pipe 51 and associated equipment can be arranged to com
`Supports or legs 105 position the inner container above
`press and condense vapors. An attempt to show the down
`the bottom wall of the outer enclosure. The lateral gap
`ward movement of globules (boiling substance as a forma
`between the containers is minimal since there is limited
`tion of liquid and vapor) is made in FIG. 2 by arrows with
`space. This spacing (A6') is enlarged on the drawing for
`the left and right sets of bubbles 46 and 48. The down
`clarity. The overflow, of course, contributes to cooling
`70 ward movement of globules is observed constantly but
`an adequate, proved explanation is only theoretical and
`of the inner container and its contents. Sets of bubbles 46,
`47 and 48 are shown in FIG. 2 and correspond in general
`not yet substantiated. Further description of these down
`ward-moving globules will be made with reference to
`to the sets of bubbles shown in FIG. 1.
`With the overflow arrangement, the heat transfer rate
`FG, 3.
`In FIG. 3, a three-liquid system is shown in container
`of the entire system is increased and a more efficient sys
`
`Immersion Systems LLC – Ex. 1009
`PGR 2021-00104 (U.S. 10,820,446 B2)
`3 of 4
`
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`3,406,244
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`a low boiling point temperature liquid located in a
`111. The above criteria apply, except that the intermediate
`bottom portion of said container, said heat generating
`liquid 113 does not have to have the heat capacity to essen
`electronic components being immersed in said low
`tially condense all of the bubbles since the remaining bub
`boiling point liquid,
`bles condense at the interface with the top liquid 115. Pref
`means for energizing said electronic components so as
`erably, the bubbles generated in the bottom liquid 116 at
`to cause a temperature rise therein which causes
`the heat producing device 117 will be condensed principally
`vaporization boiling bubbles at said electronic com
`at the lower interface 119 and in the intermediate liquid
`ponents, said boiling bubbles rising to the surface of
`113. The upper interface 121 preferably condenses essen
`said low boiling point liquid because of their lighter
`tially the remainder of the bubbles from the bottom
`density,
`liquid. A difference of boiling points (liquid-to-liquid) is
`a higher boiling point temperature liquid having a lower
`selected so as to provide this operation. In selecting liquid
`density than said low boiling point liquid and being
`materials, considerations of solubility, boiling points and
`immiscible therewith located in said container above
`inertness at the interfaces are primary. A silicate ester,
`said low boiling point liquid and forming a liquid
`water and fluorcarbon (such as CgF2) are suitable for
`three liquid-like systems. The three xylenes (meta, para
`interface therebetween,
`means for maintaining said higher boiling point liquid
`and ortho) or nitrogen, oxygen and argon can be used
`at a predetermined lower temperature than said low
`under suitable pressure. Of course, oxygen and argon are
`boiling point liquid so that said boiling bubbles will
`suitable for the two liquid systems above described. For
`be condensed at said interface and in said higher boil
`two molten metal systems, the following pairs of metals
`ing point liquid.
`are suitable: cadmium-iron, zinc-lead, chromium-bismuth
`20
`2. A system in accordance with claim 1, wherein the
`and lead-iron.
`volumes and temperatures of said low and high boiling
`Referring to the showings of bubbles in FIG. 3, the
`point liquids are selected in relation to the amount of
`left set 125 is the preferred mode of condensation at the
`heat generated by said electronic components so as to
`interface as above described. The center set of bubbles
`cause said boiling bubbles to be substantially condensed at
`127 comprises small bubbles in the bottom liquid, larger
`25
`said interface between said low and high boiling point
`bubbles in the intermediate liquid and descending or re
`liquids.
`turning globules. One of these globules 131 is enlarged
`3. A system in accordance with claim 1, wherein said
`at the left to show in all likelihood a half-moon of liquid
`low boiling point liquid is a dielectric liquid.
`and a sphere of gas. This phenomenon is not clearly under
`4. A system in accordance with claim 1, wherein a
`stood. Of course, some condensation at interface 121 re
`further higher boiling point liquid is superimposed on
`sults in droplets of solid liquid. The right set of bubbles
`said higher boiling point liquid forming a further interface
`129 shows small bubbles merging at the interface into
`therebetween, means for maintaining the temperature of
`large bubbles which escape the interface 119 and ascend
`said further higher boiling point liquid at a lower temper
`into liquid 113 to interface 121 and then descend. Above
`ature than said higher boiling point liquid upon which
`the container an enlarged, descending, double-globule 133
`it is superimposed so that boiling bubbles reaching the
`is shown and is comprised of two liquid-gas spheres (as
`above described) in another larger enveloping sphere. The
`further interface will be condensed.
`5. A system according to claim 1, wherein said higher
`showing of the portion of the left set of bubbles 125 at
`boiling point liquid is water, and said means for cooling
`the interface 119 is also intended to suggest horizontal
`said higher boiling point liquid is a remote cooling means
`movement of small bubbles to merge into a surface forma
`40
`including a heat exchanger.
`tion which breaks away into a large bubble.
`6. A system according to claim 5, wherein said remote
`From the foregoing, it is clear that the disadvantage of
`means for cooling said higher boiling point liquid includes
`having a net vapor generation as results from boiling a
`a liquid return means which returns the cooled liquid to
`single liquid is avoided. Since with the present invention
`the area in the higher boiling point liquid adjacent the
`the bubbles are essentially entrapped and condensed with
`in the liquid bulk, net vapor generation does not result.
`interface.
`7. A system according to claim 1, wherein said means
`The condenser liquid is so selected to suitably have a
`for cooling said higher boiling point liquid includes means
`lower density than, immiscibility with, higher boiling point
`by which said higher boiling point liquid overflows and
`than, a chemical inertness to, and a higher specific heat
`runs down the sides of said container to provide cooling
`than the boiling liquid so that a very high rate of heat
`thereof.
`transfer results. The various factors are so correlated that
`References Cited
`the nucleated, small bubbles rise to the interface and then
`move horizontally. In effect, the bubbles are trapped. The
`UNITED STATES PATENTS
`continued condensation is, of course, facilitated by the re
`5/1963 Borowiec et al. ---- 174-17 X
`3,091,722
`mote cooling of the condenser liquid. Only a relatively
`2,886,746 5/1959 Saby ---------------- 174-15
`thin layer of the stationary boiling liquid which is a high
`2,831,173
`4/1958 Whitman ------------ 336-58
`quality dielectric coolant is needed for conventional elec
`2,643,282
`6/1953 Greene ---------- 317-100 X
`tronic applications.
`2,479,373
`8/1949 Knotts et al. --------- 174-15
`While the invention has been particularly shown and
`2,214,865 9/1940 Troy --------------- 174-15
`described with reference to preferred embodiments thereof,
`854,312
`5/1907 Skinner et al. --------- 174-15
`it will be understood by those skilled in the art that various
`changes in form and details may be made therein without
`FOREIGN PATENTS
`departing from the spirit and scope of the invention.
`1/1962 Great Britain.
`887,383
`What is claimed is:
`1. A system for cooling heat generating electronic com
`65
`LEWISH. MYERS, Primary Examiner.
`ponents comprising:
`A. T. GRIMLEY, Assistant Examiner.
`a container,
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`Immersion Systems LLC – Ex. 1009
`PGR 2021-00104 (U.S. 10,820,446 B2)
`4 of 4
`
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