CA1119682A - Precolation cooled transformers - Google Patents
Precolation cooled transformersInfo
- Publication number
- CA1119682A CA1119682A CA000313355A CA313355A CA1119682A CA 1119682 A CA1119682 A CA 1119682A CA 000313355 A CA000313355 A CA 000313355A CA 313355 A CA313355 A CA 313355A CA 1119682 A CA1119682 A CA 1119682A
- Authority
- CA
- Canada
- Prior art keywords
- coolant
- transformer
- conduit
- container
- cooling
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F27/00—Details of transformers or inductances, in general
- H01F27/08—Cooling; Ventilating
- H01F27/10—Liquid cooling
- H01F27/18—Liquid cooling by evaporating liquids
Landscapes
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Transformer Cooling (AREA)
- Cooling Or The Like Of Semiconductors Or Solid State Devices (AREA)
Abstract
PERCOLATION COOLED TRANSFORMERS
ABSTRACT
A self-propelled vapor cooling system is employed for transformers using both a noncondensable gas and a condensable coolant. The transformer cooling duct assembly provides a heat pump for forcing the condensable coolant into a heat exchanger without the need for a fluid transfer pump.
ABSTRACT
A self-propelled vapor cooling system is employed for transformers using both a noncondensable gas and a condensable coolant. The transformer cooling duct assembly provides a heat pump for forcing the condensable coolant into a heat exchanger without the need for a fluid transfer pump.
Description
3~ 5 D- 5 5 ~ 2 BACKGROUND OF THE: INVEN :[ ION
___ _ __ _ The recent United States Govexnment ban on -the use of polychlorinated biphenols as coolants for medium and power transformers necessitates Ihe use of expensive silicone based oils for transformer cooling purposes. Since the ~uantity of oil required for total immers:ion cooling i6 in the order of hundreds of gallons, alternate means for cooling transformers have been proposed. One efficient me-thod comprises the use of a condensable fluid and utilizes the vaporiza-tion and condensatlon cycle of the fluid to remove the heat from the transformer surface during the vaporiæation portion of the cycle and transferring the heat via a heat exchanger during the condensation portion of the cycle. U.S. Patent 3,024,298 issùed March 6, 1962 to Goltsos et al discloses an evaporative-gravity cooling system using a condensable fluorochemical as a coolant for electronic devices.
Another prior art method for cooling electronic devices utilizes liquid film cooling to take heat from the electrical device during operation and transfer the heat -to a heat exchanger medium~ U.S. Patent 2,924,635 issued February 9, 1969 to Narkut discloses electrical apparatus utilizing a fluid dielectric atmosphere for both electrical insulation and as a cooling mechanism for dissipating heat developed during operation of the apparatus.
The purpose of this invention is to propose a novel pPrcolation method for vapor cooling transformers without the requirement for~a liquid distribution pump within the liquid coolant reservoir and wi~hout the requirement for force cooling the heat exchanger as described earlier for the prior art.
: ~ , . . .... . .
~: 3 0 SU~RY OF TH ` INVENTION
The invention comprises a self-propelled vapor cooling system for electrical apparatus containing a noncondensable gas ~: C à~
'.
~19~2 5D~5542 and a condensable refrigerant fluid, a heat exchanger, and a novel thermal pump arranyement for percolation cooling the electrical apparatus. The invention includes a molecular sieve vapor trap for removing und.esirable vapor phase substances that may contaminate the refrigerant.
BRIEF DESCRIPTION OF THE DRAWING
FIGURE 1 is a perspective view i.n parti~l section of one cool.ing apparatus oE the prior art;
FIGURE 2 is a front view in partial section of a further cooling apparatus of the prior art;
FIGURE 3 is a ront perspective view in partial section of the cooling apparatus accordi.ng to the invention;
FIGURE 4 is an enlarged side view in partial section oE the molecular sieve trap assembly of the apparatus o FIGURE 3;
FIGURE 4A is an alternate arrangement oE the molecular sieve txap assembly~
FIGURE 5 is a sectional view of the novel thermal pump for use with the apparatu.s of FIGURE 3;
FIGURE 6 is a graphic representation of the thermal distribution profile within the cooling ducts of transformers for various cooling mediums;
FIGURE 7 is a graphic representation of the cooling rate as a function of liquid cooling level for the percolation cooling system of this invention;
FIGURE 8 is a cross-sectional view of a further embodiment of the thermal pump of FIGURE 5;
FIGURE 9 is an enlarged cross-sectional view of a further embodirnent of the device of FIGURE 8;
~30 FIGURE~10 is a top perspective view of a transformer for use with the novel percolation cooling system of this invention;
:
___ _ __ _ The recent United States Govexnment ban on -the use of polychlorinated biphenols as coolants for medium and power transformers necessitates Ihe use of expensive silicone based oils for transformer cooling purposes. Since the ~uantity of oil required for total immers:ion cooling i6 in the order of hundreds of gallons, alternate means for cooling transformers have been proposed. One efficient me-thod comprises the use of a condensable fluid and utilizes the vaporiza-tion and condensatlon cycle of the fluid to remove the heat from the transformer surface during the vaporiæation portion of the cycle and transferring the heat via a heat exchanger during the condensation portion of the cycle. U.S. Patent 3,024,298 issùed March 6, 1962 to Goltsos et al discloses an evaporative-gravity cooling system using a condensable fluorochemical as a coolant for electronic devices.
Another prior art method for cooling electronic devices utilizes liquid film cooling to take heat from the electrical device during operation and transfer the heat -to a heat exchanger medium~ U.S. Patent 2,924,635 issued February 9, 1969 to Narkut discloses electrical apparatus utilizing a fluid dielectric atmosphere for both electrical insulation and as a cooling mechanism for dissipating heat developed during operation of the apparatus.
The purpose of this invention is to propose a novel pPrcolation method for vapor cooling transformers without the requirement for~a liquid distribution pump within the liquid coolant reservoir and wi~hout the requirement for force cooling the heat exchanger as described earlier for the prior art.
: ~ , . . .... . .
~: 3 0 SU~RY OF TH ` INVENTION
The invention comprises a self-propelled vapor cooling system for electrical apparatus containing a noncondensable gas ~: C à~
'.
~19~2 5D~5542 and a condensable refrigerant fluid, a heat exchanger, and a novel thermal pump arranyement for percolation cooling the electrical apparatus. The invention includes a molecular sieve vapor trap for removing und.esirable vapor phase substances that may contaminate the refrigerant.
BRIEF DESCRIPTION OF THE DRAWING
FIGURE 1 is a perspective view i.n parti~l section of one cool.ing apparatus oE the prior art;
FIGURE 2 is a front view in partial section of a further cooling apparatus of the prior art;
FIGURE 3 is a ront perspective view in partial section of the cooling apparatus accordi.ng to the invention;
FIGURE 4 is an enlarged side view in partial section oE the molecular sieve trap assembly of the apparatus o FIGURE 3;
FIGURE 4A is an alternate arrangement oE the molecular sieve txap assembly~
FIGURE 5 is a sectional view of the novel thermal pump for use with the apparatu.s of FIGURE 3;
FIGURE 6 is a graphic representation of the thermal distribution profile within the cooling ducts of transformers for various cooling mediums;
FIGURE 7 is a graphic representation of the cooling rate as a function of liquid cooling level for the percolation cooling system of this invention;
FIGURE 8 is a cross-sectional view of a further embodiment of the thermal pump of FIGURE 5;
FIGURE 9 is an enlarged cross-sectional view of a further embodirnent of the device of FIGURE 8;
~30 FIGURE~10 is a top perspective view of a transformer for use with the novel percolation cooling system of this invention;
:
- 2 -. ~ , ~ 5D~55~2 FIGURE 11 is a side view oE a further embodimen-t of the device of FIGURE 3; and FIGUR~ 12 is a side view of another embodiment of the system of FIGURE 3.
DESCRIPTION OF THE PREFERRED EMBODIMENT
FIG. 1 shows one type of prior art device 10 containing a fluid condensable coolant 11 within a tank which is in contact with a transformer 13 to be cooled. The transformer 13 becomes cool by heating the coolant 11 to its vaporization temperature and cau~es the coolant 11 to transfer into a heat exchanyer 14 which is forced-cooled. The coolant 11 readily condenses within the heat exchanger 14 and gives up its energy as heat of condensation.
FIG. 2 shows a liquid cooling means 15 containing a tank 16 and a reservoir 17 containing a liquid coolant 18. The - device 15 further contains a pump 19 and a plurality of nozzles 9 for spraying the coolant 18 in liquid droplet form over the surface of a transformer 20. The coolant 18 forms a thin liquid film over the surface of the transformer 20 and the liquid film upon contacting the hot transformer surface readily evaporates and becomes transported in a gaseous state into a condenser 21 for transferring the heat obtained from the transformer 20 to the condenser 21 by the heat of condensation. An expansion tank 22 containing a noncondensable gas is often employed with systems of this kind and an auxiliary heat exchanger 23 may be required~
FIGURE 3 shows one embodiment of the novel percolation cooling apparatus employing the principles of this invention.
The apparatus 24 includes a boiler 25 consisting of a tank 26, a piece of electrical apparatus such as a transformer 27 which .
.' :
~ ~ 3 -~. .
"
~'','
DESCRIPTION OF THE PREFERRED EMBODIMENT
FIG. 1 shows one type of prior art device 10 containing a fluid condensable coolant 11 within a tank which is in contact with a transformer 13 to be cooled. The transformer 13 becomes cool by heating the coolant 11 to its vaporization temperature and cau~es the coolant 11 to transfer into a heat exchanyer 14 which is forced-cooled. The coolant 11 readily condenses within the heat exchanger 14 and gives up its energy as heat of condensation.
FIG. 2 shows a liquid cooling means 15 containing a tank 16 and a reservoir 17 containing a liquid coolant 18. The - device 15 further contains a pump 19 and a plurality of nozzles 9 for spraying the coolant 18 in liquid droplet form over the surface of a transformer 20. The coolant 18 forms a thin liquid film over the surface of the transformer 20 and the liquid film upon contacting the hot transformer surface readily evaporates and becomes transported in a gaseous state into a condenser 21 for transferring the heat obtained from the transformer 20 to the condenser 21 by the heat of condensation. An expansion tank 22 containing a noncondensable gas is often employed with systems of this kind and an auxiliary heat exchanger 23 may be required~
FIGURE 3 shows one embodiment of the novel percolation cooling apparatus employing the principles of this invention.
The apparatus 24 includes a boiler 25 consisting of a tank 26, a piece of electrical apparatus such as a transformer 27 which .
.' :
~ ~ 3 -~. .
"
~'','
3;~ rl D 5 5 '~ 2 generates heat during opera~i.oJI, and a con~ensab:le coolant medlum 28. Sys~em 24 further includes a heat exch.lng~r 29 having an upper mani:fold 30, a lower maniEold 31, para3.lel headers 40, and a plurali~y of interconnecting cooling tubes 32. An expansion tank 33 contain:ing a noncondensable gas i.s often employed when the coolant Z8 provides the dllal function of percolation cooling and acts as a dielecrr:ic for the electrical apparatus employed. The noncolldensable gas provides the dielectric medium for electrically insulating the electrical apparatus when the tempera~ure is insuficient to cause the coolant 28 to beconle vaporized and to completely cover the electrical apparatus 27. The expansion tank 33 is connected to the heat exchanger 29 at both the upper and lower manifolds 30, 31, and is connected to the boiler 25 by means of duct 34.
Duct 34 houses a container 35 of a molecular sieve substance 36 the purpose of which will be described ~elow. I'ransormer 27 has a feed-through bushing 5~ attached for making electrical contact with the transformer 27 as is common with medium and ~ power transformer assembliés.
;: 20 The duct 34 is shown in enlarged detail i~ FXGUR~ 4 where the top of tank 26 is connecked to lower manifold 3i by means of duct 34. The container 35 of molecular sie~e m~terial 36 contains a contaminant trap 37 at the bottom section thereof~
The vapor transmission path for the coolant 28 is indicated by arrows and proceeds as follows. - Upon becomlng heated, and vaporizing the coolant 28 enters into the inlet 38 to within.
i: :
the top:portion 39 of the duct 34 down through the molecular sieve:~material 36;into the lower manifold 31 by means of mani~fold inlet 31. The coolant 28 CoDsists of a vaporizable chlorof;luorocarbon~such as trichlorotrifluoroethane which may : -4-:
~ )S5~
react ~ith water vapo-r ~Ind 'become disas~;oci,~ d (l~ in~-J
opera-tion. The type of t-ransformeI ~,o he oooled genera'~l,y contains a wrapp:ing of paper in,llLa~ion which at t'he operating temperatur~s involved may yield an amount ~f' water vapor which canno~ be completely removed during the initial thermal treating process. The purpose o the molecular sieve material 36 therefore is ~o remove any water vapor or other harm~'ul l:i,quid substaIlces that ma~ be evolved from the trans~ormer paper and pi,,ked up ky the coolant material 28 during its vapor transi,tion process. A partieularly effective granular molecular sieve material 36 is a zeolite type 4A made by the Linde Division o the IJn:ion Carbide Corpo-ration. It has been determined that the Linde molecular sieve material 36 effectively removes all traces o~ water vapor from the coolant 28 and that other liquid contaminants remain in the trap 37 provided at the bottom section o~ the duct 34. In the absence of the molecular sieve material 36, the - coolant material 28 ~trichlorotrifluoroethane) may become cloudy. The coolant 28 when used with the sieve material 36 ~ 20 remains clear during con-tinuous operation. Ater passing - through the molecular sieve material 36 the ~aporized coolant 28 transmits into the lower manifold 31 by means o~ manifcld inlet 31' and from there out to the cooling tubes 32 by means of the headers 40. The vaporized coolant 28 readily cond~nses 25`; ~ within the tubes 32 and returns in liquid orm by means of a ' separate return through the lower maniold 31 back into the ~ank 26 via condensate return pipe 41.
An alternate arrangement of the molecular sieve 36 is ~ .
~i shown in FIGVRE 4A. The duct 34 shown in FIGURE 4 has been .j ` 30 eliminated and the molecular sieve 35 is included in the lower .~
~ manifold 31. The vapor transmission p~th for the coolant 28 . .
, . . .
.. , . . . . ............. : , . ..... . . .
: ' ' 6~2 51) r~ 5 /t 2 is indicated by arrows and proceeds as follows - llpOn b~com:ing heated and vaporizing the cool.ant 28 cnters into the inlet 38 inside the bottorn manifold 31 ancl down -through -che molecular sieve material 36 into headers 40 ~nd -then into cooli-n~ tubes 32. The vaporized coolan~ 28 readily condenses within the tubes 32 and returns in liquid for:m by rn~ans of a separate return pipe 41 into the tank 26. The re-turn pipe 41 ext~nds above the bottom of manifold .;1 so that a trap 37 i.s provided ~or other liquid contaminants.
In FIGUR~S 4 and 4A the co~ld.erlsate returTI 41 excends below the level oE the coolant 28 in the kank 26 so that the vapor phase of coolant 28 must enter ~he inlet pipe 38 (above the liquid level) through the moleculaT sieve 36. The molecular sieve 36 can also be effective by proper sizing of the pipes 41 and 38. With ~he return pipe 41 above the liquid level of coolant 28 the vapor phase of coolant 28 enters bo~h the return pipe 41~and t~e inlet pipe 38. By proper sizing o:E the pipes 41 and 38, as is well known in the art of fluid mechanics, sufficient vapor can be made to flow through inlet.pipe 38 and sie~e 36 to remove water. Since vapor is continuously formed, condensed, and regenerated,it is not necessary to provide 100 per cent vapor flow through sieve 36. Also, by proper . sizing of pipe 41 the upward vapor flow through pipe 41 will ~; :: not interfere with the downward condensate return through ~1.
The novel heat pipe arrangement 42 of FIGURE 5 is described as follows. The tank 26 containing the transformer 27 and li~uid coolant 28 having a liquid le~el 43 is particN-larly arranged ]n the following manner. The trans~ormer 27 :contains a plurality of transformer windings 45 with a series .
~ ~ ~ o~f;passages SUC}l as cooling ducts 44 extending from the trans-~; ~
,:
' ' : . . -6-.
~ 5l)55~
.
f~rmer bottom 46 to the t-ransformer -top 47 and a corlcen-trically located core member 48. The transFormer thermal pumpirl~
assembly 42 is designed to transfer the coolant 28 ~ron the transformer bot~om sectlon 46 through the ducts 44 by rneans of the thermal gradien~ existing with:in the plurality of ducts 44. The cooling ducts 44 provide a conduit for the cool~nt 28 which becomes heated in transit and cools the transformer 27 by the change of state from a liquid to a vapor. The temperature distribllliorl profile within the cooling ducts 44 for a liquid level ~3 as shown is 5uch that the temperature of the coolan~ 28 at the transformer bottom section 46 is lower than the temperature at a point P
corresponding to the liquld level 43 since the heating mechanism ;s the wattage generated by the transformer 27 and the point P is subjected to a smaller trans~ormer cooling surface than for example point P'in the vicinity o~ the trans-~. .
former bot~om section 46. The temperature at point P is alsohigher than the temperature at point P" at the transormer top section 47 for the heat pump of this invention to be operative. Point P" is a lower temperature than polnt P
since point P" is subjected to a greater cooling su.~ace than ; ~ point P,provided the proper liquid level is maintained. When power is applied to the transformer 27 a plurali~y of bubbles ; 49 begin to move in an upward direction within the cooling ducts 44 and become heated to a greater degree as they proceed ~: :
further within the trans~ormer 27 since the region at point P
has a higher temperature as described earlier. As the bubbles 49 contlnue to proceed to the vicinity o the transformer top ; ;s~ection 47 they acquiTe enough thermal energy to leave the ; transformer 27 at: the vicinity of point P" as vapor droplets :
~ 49' in the direcl:îon indicated by the directional arrows.
, : .
: ::~:
~ ~ -7-~J)5S~2 Since the droplets 49' foree coolcln~ 28 through the ~ucts ~4 to the transformer top section ~7, the top sectiorl ~7 becomes cooled by the process of evapora~ion of coolant 28. Further bubbles 49 enter into the cooling ducts 44 and proceed through the regions indicaced at points P', and P" ln a continuous proc~ss during the time the tr~lnsformer is operating.
This process is somewhat similar to the perco~ 'cion effect wsed for continuously redistributirlg water in a col~Eee percolator.
The temperature distribution within the cooling ducts 44 for transormer 27 is shown in FIGURB 6. The temperature in degrees C is plotted as a function of the relative length of the ducts 44 for the same transformer i~ it were air-cooled A, oil-cooled Bl and percolation-cooled C. The air-cooled temperature gradient A shows that the temperature continuously increases from the bottom section of the transformer through the center sec~ion -to the top of the transormer since the transformer itself is its own source o heat and the air-cooling mechanism of heat transer is insufficient to cool the entire transformer uniformly. The temperature gradient for an oil-~ cooled transformer ~ shows tha~ the temperature gradient rom `- the bottom to the top of the transormer continuously increases at a slower rate than that for the aiT~cooled transformer A.
, The temp~ra~ures ob~ained with oil or air cooling for ~his ~, ~
2S transformer are greater than permissable with the insulations ;
commonly used. In order to use oil or air cooling, additional cooling ducts must be provided to lower the temperatures. Thus, additional conductor material is required for oil or air cooling as compared with percolation cooling. The temperature gradient , 30 for the percolation-cooled transformer C is as follo~s.
:', :' , ': , ~ 55~2 At the bottom regi.on of the transformer 27 a~ po:int P~
the ends of the windings are exposed to the coolant 28 which is vaporized due to the heat generaked by the winding conductors, thus, cooling ~he bo~tom o-f the winding 450 rrhe coolant 28 enters the ducts 44 and vaporiæes due to contact with the part of the liinding 45 next to the duct 44. ~ince the bottom of the winding 45 has a greater surface area exposed to the coolant it will be at a J.ower temperature t!lan -the inner parts of the winding 45. Thc inner parts are cnoled by vaporization of the coolant 28 i.n ducts 44 and by thermal ; conduction to thè cooler ends of the winding 45. Upon vapori~a~ion the coolant 28 forms bubbles 49 which rise rapidly upward through the ducts 44 forcing some of the liquid phase of coolant 28 to the top of the ducts 44 and then onto the top end of the winding 45. The liquid coolant 28 is vaporized upon contact ~ith the upper surface o-f ducts 44 ~1 and the upper end of the winding 45. It was, therefore, :: ~ determined that for the mechanism of percolation cooling, that is, when coolant 28 is provided within cooling ducts 44, 2a and evaporation rapidly takes place at the transformer upper ~ surface 47, the rate of heat transfer away from the transformer -; 27 is su~ficient to cool the top surface 47, of the trans~ormer ~ 27 at a rate that is equal to the rate at which the transformer ': : : 27 becomes heated during normal operating conditions. The , ~ . .
2~5 temperature at point P":at the top surface 47 can be as low as . the temperature~indicated at point P' at the transformer ..:
: bottom 46 depending upon the boiling point of the coolant 28, : the liquid le~el 43, and the dimensions of the cooling ducts 44.
~ The cooling rate for a plurality of heat pumps 42 having ¦ ~ 3Gl :~differing liquid l~evels 43 for a fixed coolant composition is , 1 ;
~: : .. . . 9 .. ~ ~ . .
,, ~. . . . . . .
3~
r)r)5s~,2 shown in FIGURE 7. Xt was therl determi.rled. tha~ -tile l:iqllid level ~3 expressed in per cent height re:lat:ive ~o the transformer top section 47 in FIG[JR~ 5 could be dec7ea:;.rd without seriously efecting ~he e:ffiçiency of the trarls:former cooling rate for liquid levels down to less than 75% of the maximum dimension indicated. The cooling rate profile R
remains relatively steady down -to a 75~ liquid Jev~l as indicated in therma} units per unit time and begi.ns to decrease for liquid levels less ~han approximately 60%. P'ol li..rluid levels between 60 and 50% the cool.ing rate decreased sub stantially and below 50 per cent the cooling rate was not ~dequate. This phenomenon is not as yet well understood, but is believed ~o depend upon the heat trans~er characteris~ics for the coolant 28~ as well as the geometry and numbèr o~
transformer cooling ducts, and the power rating of the trans-.
former. FIGURE 6 indicates that the temperature at any distance ~ within the percolation-cooled device C is lower than that ; within the oil-cooled transformer B and the air-cooled trans-former A.
: FIGURE 8 is a further embodiment of the transformer .
~.. .. heat pump 42 o~ FIGURE 5. In the embodiment of FIGURE 8 the , , , ` transformer 27 containing the plurality of cooling ducts 44 and vapor bubbles 49 is modified by duct extensicns 50 coincident with th ends of the cooling.ducts 44 at the ~ 25 trans~ormer top sur~ace 47. The extensions 50 carry the vapor bubbles 49 to an extended height h abvve the top .
: surface 47 and deposits the liquid 28 within a specially d~esigned distribution tray 51 having a plurality of spaced perforations 52. The embodiment of FIGURE 8 combines the percolation cooling me-hod of this invention with the liquid ' , ~ , ' .~ . , .
~ - " ' " . . .
~ 32 SD5S42 sur:face film e-vaporat:ion o:~ the ~r:ior art to furth~r increase the coollng efficiency. The distribu-tor tray 51. cul1ects the coolant 28 in liquid form ~nd rerl:is~ributes the ooolant 28 in the form of drople~s 49' which subsequently drop throu~h the perforations 52 onto the ~rans:former top surface 47. To keep a continuous ~low of coolant 28 OTltO the top surface of the transformer coils 45 an upwardly extending dam member 53 is provided at the top surface 47 of the transformer 27 as indicated in FIGURE 8.
FIGURE 9 shows a further use ~or the extension 50 o~
the cooling duct 44, In this embodiment the extension S0 . is brought up into close contact with a busbar 54 so that the liquid droplets 49' can contact and cool busbar 54.
The transformer 27 for providing the heat pump 42 of this invention is shown in enlarged top perspective view in FIGURE lO. The ducts 44 between ~he transformer coils 45 at the transforme~r top section 47 have a wldth t~WI~ and a length . "L" as indicated. The:required number.of ducts 44 are used . in order to maintain the operating temperature below the maximum permissable value. The width "W" is approximately 3/16 of an inch, and the length "L" is approximately l-l/2 inches. The core 48 is centrally located as is common with ; transformers of the medium and power type. The dimensions~
: number, ~nd location of the tr~nsformer cooling ducts 44 are .~ 25 determinative o:E the quantity of coolant used to provide the heat pump of this invention and it is anticipated tha~ a substantial savings of transformer coolant fluid can be realized by a p-roper heat pump design. For oil-cooled trans-formers having the tempera~ure gradient indicated at B in FIGURE 6 approximately 155 gallons of coolant oil is generally required whereas for the same size transformer 50 gallons of : ~ :
, ~:
., I
' ' ' ' - 1 1 , , ' ~ .. : . .
~ 5~)5S~2 coo.Lant are recluired to pro~ide the terrlperature gradient indicated .for the percolation-cooled device at C. Ihe hea~
pump device of this in~ention, there:fore~, pro-vides bf.~tter cooling e-ffi.ciency than standard oil-cooled total immersion prior art systems at d subs~antial savings in materials costs.
Further embodiments o~ the percolat.ion cooled trans-formers of this invention are S}IOW]l in FIGIIR~S 11 AND 12. As described earli~r a noncondensable gas such as n:atrogen, C2~6, C2ClF5. SF6 is requently employed as a dielectr.ic for providing insulation between the transformel windings when the -transformer liquid coolant is at a low temperature. The noncondensable ga~
pressure also determines the boiling temperature o:~ the con-densable coolant and is adjusted so that the condensable coolant boils within the operating range o~ the transformer temperature.
For the trichlorotrifluoroethane coolantg Freon 113 such as the type manufactured by DuPont for example~ can be used within the heat pump 42 of FIGURE 5. A medium transformer rated at 18000 watts three phase operated continuously at a boiling temperature of 67~C when the nitrogen fill pressure was ad-justed to g.ive a condensable vapor pressure o 12 P.S.I.G.
: It is anticipated that the operating temperature character~
~ . istics can be accuratel~ controlled by the duct dimens:lolls ; ànd the coolant boiling temperature~ as deter~ined by the - nitrogen ill pressure, provided a quantity of coolant :: ~25 always remains in the li~ui~ ~ha~e. If the entire quantity of coolant vaporized the pressure within the system would behave as an ideal gas and increase in proportion to temperature.
:~ The use:of the noncondensable gas generally requires an upper : ~ man:ifold 30 and an expansion tank 33 as shown in FIGURES 3 and ,~ : 30 11 for the following reasons. The expansion tank 33 provides . -12- .
~ , , ' .
~ 5D55~2 a receptacle .Eor -~he noncondensable gas a-~ter ~he cl~ndellsable gas has become sufficiently vaporized to d:isplace the non-cond~nsable gtas and ~o expel it ~rom the vi.cinity o t~le transformer windings. The upper manifold 30 is generally requlred when the liquid co.olant 28 is heat treated to outgas any residual noncondensable gases such as air absorbed by the coolant during transportation and storage. In order to outgas the coolant 28 the trans:~ormer is short circuited to cause the trans~ormer to become heated and to separate the absorbed air from coolant 28. The heated air separates from the coolant 28 in the outgassing -process and ente-rs the expansion tank ~3 after passing through condenser tubes 32. The air then readi.ly transmits into upper mani~old 30 which is connected to the expansion tank 33 by means of connecting pipe 55 and connecting valve 56. Once the transformer coolant has been completely outgassed from residual air and the outgassed air is contained wlthin expansion tank 33 the upper manifold 30 is isolated from the expansion tank 33 by closing valve S6.
' The air is then removed from the expansion tank 33 by evacu-ation with a vacuum pump. A known quantity of the desired :~; noncondensable gas nitrogen, SF6, C2F6, or C2ClFs is then :~ added to the expansion tank 33 through a ~illing valve S~.
; ~ The valves 56 and 58 are then opened and the noncondensable ~ gas is allowed to flow throughout the system. During operation ,, . ~ .
25 the pipe 57 serves to return any condensate of coolant 28 ~; from the expansion tank to the main liquid supply. Condensate of coolant 28 may form in expansion tank 33 due to 1uctuations n ambi:ent temperature. Pipe S7 is connected to the lowest , .. .
point of expansion tank 33 to mlnimize condensate hold up in ~he expansion tank.
i ., :
~ .
: .
5~55~
The embodiment oE E'IGURE 12 is similar -to -the er~odiment of FIGURE 11 except that the upper manifold 30, -the connec-ting pipe 55, the connecting valve 56 and drain valve 58 can ba dispensed with. It has been discovered that the transformer coolant can be pre-evacuated by heating and outgassiny the coolant prior to filling within the transformer such that the steps indicated earlier for FIGURE 11 are no longer required.
Once the transformsr coolant is completely outgassed particular care is taken to insure that the outgassed coolant does not reabsorb air in the final transformer filling stage.
Althou~h the percolation cooling system employing the heat pump of this invention is directed to applications involving medium and power transformers, this is by way of example only. The method and apparatus employed within the examples shown can be applied to cool other type of electrical apparatus providing the heat pump trans~er design of this invention can be incorporated within the electrical apparatus involved.
It should also be readily apparent that ~or certain ranges of am~ient temperatures and condensable coolants the noncondensable gas may be omitted wi-thout effecting -the operation of thé apparatus as described.
, ',~
:
,
Duct 34 houses a container 35 of a molecular sieve substance 36 the purpose of which will be described ~elow. I'ransormer 27 has a feed-through bushing 5~ attached for making electrical contact with the transformer 27 as is common with medium and ~ power transformer assembliés.
;: 20 The duct 34 is shown in enlarged detail i~ FXGUR~ 4 where the top of tank 26 is connecked to lower manifold 3i by means of duct 34. The container 35 of molecular sie~e m~terial 36 contains a contaminant trap 37 at the bottom section thereof~
The vapor transmission path for the coolant 28 is indicated by arrows and proceeds as follows. - Upon becomlng heated, and vaporizing the coolant 28 enters into the inlet 38 to within.
i: :
the top:portion 39 of the duct 34 down through the molecular sieve:~material 36;into the lower manifold 31 by means of mani~fold inlet 31. The coolant 28 CoDsists of a vaporizable chlorof;luorocarbon~such as trichlorotrifluoroethane which may : -4-:
~ )S5~
react ~ith water vapo-r ~Ind 'become disas~;oci,~ d (l~ in~-J
opera-tion. The type of t-ransformeI ~,o he oooled genera'~l,y contains a wrapp:ing of paper in,llLa~ion which at t'he operating temperatur~s involved may yield an amount ~f' water vapor which canno~ be completely removed during the initial thermal treating process. The purpose o the molecular sieve material 36 therefore is ~o remove any water vapor or other harm~'ul l:i,quid substaIlces that ma~ be evolved from the trans~ormer paper and pi,,ked up ky the coolant material 28 during its vapor transi,tion process. A partieularly effective granular molecular sieve material 36 is a zeolite type 4A made by the Linde Division o the IJn:ion Carbide Corpo-ration. It has been determined that the Linde molecular sieve material 36 effectively removes all traces o~ water vapor from the coolant 28 and that other liquid contaminants remain in the trap 37 provided at the bottom section o~ the duct 34. In the absence of the molecular sieve material 36, the - coolant material 28 ~trichlorotrifluoroethane) may become cloudy. The coolant 28 when used with the sieve material 36 ~ 20 remains clear during con-tinuous operation. Ater passing - through the molecular sieve material 36 the ~aporized coolant 28 transmits into the lower manifold 31 by means o~ manifcld inlet 31' and from there out to the cooling tubes 32 by means of the headers 40. The vaporized coolant 28 readily cond~nses 25`; ~ within the tubes 32 and returns in liquid orm by means of a ' separate return through the lower maniold 31 back into the ~ank 26 via condensate return pipe 41.
An alternate arrangement of the molecular sieve 36 is ~ .
~i shown in FIGVRE 4A. The duct 34 shown in FIGURE 4 has been .j ` 30 eliminated and the molecular sieve 35 is included in the lower .~
~ manifold 31. The vapor transmission p~th for the coolant 28 . .
, . . .
.. , . . . . ............. : , . ..... . . .
: ' ' 6~2 51) r~ 5 /t 2 is indicated by arrows and proceeds as follows - llpOn b~com:ing heated and vaporizing the cool.ant 28 cnters into the inlet 38 inside the bottorn manifold 31 ancl down -through -che molecular sieve material 36 into headers 40 ~nd -then into cooli-n~ tubes 32. The vaporized coolan~ 28 readily condenses within the tubes 32 and returns in liquid for:m by rn~ans of a separate return pipe 41 into the tank 26. The re-turn pipe 41 ext~nds above the bottom of manifold .;1 so that a trap 37 i.s provided ~or other liquid contaminants.
In FIGUR~S 4 and 4A the co~ld.erlsate returTI 41 excends below the level oE the coolant 28 in the kank 26 so that the vapor phase of coolant 28 must enter ~he inlet pipe 38 (above the liquid level) through the moleculaT sieve 36. The molecular sieve 36 can also be effective by proper sizing of the pipes 41 and 38. With ~he return pipe 41 above the liquid level of coolant 28 the vapor phase of coolant 28 enters bo~h the return pipe 41~and t~e inlet pipe 38. By proper sizing o:E the pipes 41 and 38, as is well known in the art of fluid mechanics, sufficient vapor can be made to flow through inlet.pipe 38 and sie~e 36 to remove water. Since vapor is continuously formed, condensed, and regenerated,it is not necessary to provide 100 per cent vapor flow through sieve 36. Also, by proper . sizing of pipe 41 the upward vapor flow through pipe 41 will ~; :: not interfere with the downward condensate return through ~1.
The novel heat pipe arrangement 42 of FIGURE 5 is described as follows. The tank 26 containing the transformer 27 and li~uid coolant 28 having a liquid le~el 43 is particN-larly arranged ]n the following manner. The trans~ormer 27 :contains a plurality of transformer windings 45 with a series .
~ ~ ~ o~f;passages SUC}l as cooling ducts 44 extending from the trans-~; ~
,:
' ' : . . -6-.
~ 5l)55~
.
f~rmer bottom 46 to the t-ransformer -top 47 and a corlcen-trically located core member 48. The transFormer thermal pumpirl~
assembly 42 is designed to transfer the coolant 28 ~ron the transformer bot~om sectlon 46 through the ducts 44 by rneans of the thermal gradien~ existing with:in the plurality of ducts 44. The cooling ducts 44 provide a conduit for the cool~nt 28 which becomes heated in transit and cools the transformer 27 by the change of state from a liquid to a vapor. The temperature distribllliorl profile within the cooling ducts 44 for a liquid level ~3 as shown is 5uch that the temperature of the coolan~ 28 at the transformer bottom section 46 is lower than the temperature at a point P
corresponding to the liquld level 43 since the heating mechanism ;s the wattage generated by the transformer 27 and the point P is subjected to a smaller trans~ormer cooling surface than for example point P'in the vicinity o~ the trans-~. .
former bot~om section 46. The temperature at point P is alsohigher than the temperature at point P" at the transormer top section 47 for the heat pump of this invention to be operative. Point P" is a lower temperature than polnt P
since point P" is subjected to a greater cooling su.~ace than ; ~ point P,provided the proper liquid level is maintained. When power is applied to the transformer 27 a plurali~y of bubbles ; 49 begin to move in an upward direction within the cooling ducts 44 and become heated to a greater degree as they proceed ~: :
further within the trans~ormer 27 since the region at point P
has a higher temperature as described earlier. As the bubbles 49 contlnue to proceed to the vicinity o the transformer top ; ;s~ection 47 they acquiTe enough thermal energy to leave the ; transformer 27 at: the vicinity of point P" as vapor droplets :
~ 49' in the direcl:îon indicated by the directional arrows.
, : .
: ::~:
~ ~ -7-~J)5S~2 Since the droplets 49' foree coolcln~ 28 through the ~ucts ~4 to the transformer top section ~7, the top sectiorl ~7 becomes cooled by the process of evapora~ion of coolant 28. Further bubbles 49 enter into the cooling ducts 44 and proceed through the regions indicaced at points P', and P" ln a continuous proc~ss during the time the tr~lnsformer is operating.
This process is somewhat similar to the perco~ 'cion effect wsed for continuously redistributirlg water in a col~Eee percolator.
The temperature distribution within the cooling ducts 44 for transormer 27 is shown in FIGURB 6. The temperature in degrees C is plotted as a function of the relative length of the ducts 44 for the same transformer i~ it were air-cooled A, oil-cooled Bl and percolation-cooled C. The air-cooled temperature gradient A shows that the temperature continuously increases from the bottom section of the transformer through the center sec~ion -to the top of the transormer since the transformer itself is its own source o heat and the air-cooling mechanism of heat transer is insufficient to cool the entire transformer uniformly. The temperature gradient for an oil-~ cooled transformer ~ shows tha~ the temperature gradient rom `- the bottom to the top of the transormer continuously increases at a slower rate than that for the aiT~cooled transformer A.
, The temp~ra~ures ob~ained with oil or air cooling for ~his ~, ~
2S transformer are greater than permissable with the insulations ;
commonly used. In order to use oil or air cooling, additional cooling ducts must be provided to lower the temperatures. Thus, additional conductor material is required for oil or air cooling as compared with percolation cooling. The temperature gradient , 30 for the percolation-cooled transformer C is as follo~s.
:', :' , ': , ~ 55~2 At the bottom regi.on of the transformer 27 a~ po:int P~
the ends of the windings are exposed to the coolant 28 which is vaporized due to the heat generaked by the winding conductors, thus, cooling ~he bo~tom o-f the winding 450 rrhe coolant 28 enters the ducts 44 and vaporiæes due to contact with the part of the liinding 45 next to the duct 44. ~ince the bottom of the winding 45 has a greater surface area exposed to the coolant it will be at a J.ower temperature t!lan -the inner parts of the winding 45. Thc inner parts are cnoled by vaporization of the coolant 28 i.n ducts 44 and by thermal ; conduction to thè cooler ends of the winding 45. Upon vapori~a~ion the coolant 28 forms bubbles 49 which rise rapidly upward through the ducts 44 forcing some of the liquid phase of coolant 28 to the top of the ducts 44 and then onto the top end of the winding 45. The liquid coolant 28 is vaporized upon contact ~ith the upper surface o-f ducts 44 ~1 and the upper end of the winding 45. It was, therefore, :: ~ determined that for the mechanism of percolation cooling, that is, when coolant 28 is provided within cooling ducts 44, 2a and evaporation rapidly takes place at the transformer upper ~ surface 47, the rate of heat transfer away from the transformer -; 27 is su~ficient to cool the top surface 47, of the trans~ormer ~ 27 at a rate that is equal to the rate at which the transformer ': : : 27 becomes heated during normal operating conditions. The , ~ . .
2~5 temperature at point P":at the top surface 47 can be as low as . the temperature~indicated at point P' at the transformer ..:
: bottom 46 depending upon the boiling point of the coolant 28, : the liquid le~el 43, and the dimensions of the cooling ducts 44.
~ The cooling rate for a plurality of heat pumps 42 having ¦ ~ 3Gl :~differing liquid l~evels 43 for a fixed coolant composition is , 1 ;
~: : .. . . 9 .. ~ ~ . .
,, ~. . . . . . .
3~
r)r)5s~,2 shown in FIGURE 7. Xt was therl determi.rled. tha~ -tile l:iqllid level ~3 expressed in per cent height re:lat:ive ~o the transformer top section 47 in FIG[JR~ 5 could be dec7ea:;.rd without seriously efecting ~he e:ffiçiency of the trarls:former cooling rate for liquid levels down to less than 75% of the maximum dimension indicated. The cooling rate profile R
remains relatively steady down -to a 75~ liquid Jev~l as indicated in therma} units per unit time and begi.ns to decrease for liquid levels less ~han approximately 60%. P'ol li..rluid levels between 60 and 50% the cool.ing rate decreased sub stantially and below 50 per cent the cooling rate was not ~dequate. This phenomenon is not as yet well understood, but is believed ~o depend upon the heat trans~er characteris~ics for the coolant 28~ as well as the geometry and numbèr o~
transformer cooling ducts, and the power rating of the trans-.
former. FIGURE 6 indicates that the temperature at any distance ~ within the percolation-cooled device C is lower than that ; within the oil-cooled transformer B and the air-cooled trans-former A.
: FIGURE 8 is a further embodiment of the transformer .
~.. .. heat pump 42 o~ FIGURE 5. In the embodiment of FIGURE 8 the , , , ` transformer 27 containing the plurality of cooling ducts 44 and vapor bubbles 49 is modified by duct extensicns 50 coincident with th ends of the cooling.ducts 44 at the ~ 25 trans~ormer top sur~ace 47. The extensions 50 carry the vapor bubbles 49 to an extended height h abvve the top .
: surface 47 and deposits the liquid 28 within a specially d~esigned distribution tray 51 having a plurality of spaced perforations 52. The embodiment of FIGURE 8 combines the percolation cooling me-hod of this invention with the liquid ' , ~ , ' .~ . , .
~ - " ' " . . .
~ 32 SD5S42 sur:face film e-vaporat:ion o:~ the ~r:ior art to furth~r increase the coollng efficiency. The distribu-tor tray 51. cul1ects the coolant 28 in liquid form ~nd rerl:is~ributes the ooolant 28 in the form of drople~s 49' which subsequently drop throu~h the perforations 52 onto the ~rans:former top surface 47. To keep a continuous ~low of coolant 28 OTltO the top surface of the transformer coils 45 an upwardly extending dam member 53 is provided at the top surface 47 of the transformer 27 as indicated in FIGURE 8.
FIGURE 9 shows a further use ~or the extension 50 o~
the cooling duct 44, In this embodiment the extension S0 . is brought up into close contact with a busbar 54 so that the liquid droplets 49' can contact and cool busbar 54.
The transformer 27 for providing the heat pump 42 of this invention is shown in enlarged top perspective view in FIGURE lO. The ducts 44 between ~he transformer coils 45 at the transforme~r top section 47 have a wldth t~WI~ and a length . "L" as indicated. The:required number.of ducts 44 are used . in order to maintain the operating temperature below the maximum permissable value. The width "W" is approximately 3/16 of an inch, and the length "L" is approximately l-l/2 inches. The core 48 is centrally located as is common with ; transformers of the medium and power type. The dimensions~
: number, ~nd location of the tr~nsformer cooling ducts 44 are .~ 25 determinative o:E the quantity of coolant used to provide the heat pump of this invention and it is anticipated tha~ a substantial savings of transformer coolant fluid can be realized by a p-roper heat pump design. For oil-cooled trans-formers having the tempera~ure gradient indicated at B in FIGURE 6 approximately 155 gallons of coolant oil is generally required whereas for the same size transformer 50 gallons of : ~ :
, ~:
., I
' ' ' ' - 1 1 , , ' ~ .. : . .
~ 5~)5S~2 coo.Lant are recluired to pro~ide the terrlperature gradient indicated .for the percolation-cooled device at C. Ihe hea~
pump device of this in~ention, there:fore~, pro-vides bf.~tter cooling e-ffi.ciency than standard oil-cooled total immersion prior art systems at d subs~antial savings in materials costs.
Further embodiments o~ the percolat.ion cooled trans-formers of this invention are S}IOW]l in FIGIIR~S 11 AND 12. As described earli~r a noncondensable gas such as n:atrogen, C2~6, C2ClF5. SF6 is requently employed as a dielectr.ic for providing insulation between the transformel windings when the -transformer liquid coolant is at a low temperature. The noncondensable ga~
pressure also determines the boiling temperature o:~ the con-densable coolant and is adjusted so that the condensable coolant boils within the operating range o~ the transformer temperature.
For the trichlorotrifluoroethane coolantg Freon 113 such as the type manufactured by DuPont for example~ can be used within the heat pump 42 of FIGURE 5. A medium transformer rated at 18000 watts three phase operated continuously at a boiling temperature of 67~C when the nitrogen fill pressure was ad-justed to g.ive a condensable vapor pressure o 12 P.S.I.G.
: It is anticipated that the operating temperature character~
~ . istics can be accuratel~ controlled by the duct dimens:lolls ; ànd the coolant boiling temperature~ as deter~ined by the - nitrogen ill pressure, provided a quantity of coolant :: ~25 always remains in the li~ui~ ~ha~e. If the entire quantity of coolant vaporized the pressure within the system would behave as an ideal gas and increase in proportion to temperature.
:~ The use:of the noncondensable gas generally requires an upper : ~ man:ifold 30 and an expansion tank 33 as shown in FIGURES 3 and ,~ : 30 11 for the following reasons. The expansion tank 33 provides . -12- .
~ , , ' .
~ 5D55~2 a receptacle .Eor -~he noncondensable gas a-~ter ~he cl~ndellsable gas has become sufficiently vaporized to d:isplace the non-cond~nsable gtas and ~o expel it ~rom the vi.cinity o t~le transformer windings. The upper manifold 30 is generally requlred when the liquid co.olant 28 is heat treated to outgas any residual noncondensable gases such as air absorbed by the coolant during transportation and storage. In order to outgas the coolant 28 the trans:~ormer is short circuited to cause the trans~ormer to become heated and to separate the absorbed air from coolant 28. The heated air separates from the coolant 28 in the outgassing -process and ente-rs the expansion tank ~3 after passing through condenser tubes 32. The air then readi.ly transmits into upper mani~old 30 which is connected to the expansion tank 33 by means of connecting pipe 55 and connecting valve 56. Once the transformer coolant has been completely outgassed from residual air and the outgassed air is contained wlthin expansion tank 33 the upper manifold 30 is isolated from the expansion tank 33 by closing valve S6.
' The air is then removed from the expansion tank 33 by evacu-ation with a vacuum pump. A known quantity of the desired :~; noncondensable gas nitrogen, SF6, C2F6, or C2ClFs is then :~ added to the expansion tank 33 through a ~illing valve S~.
; ~ The valves 56 and 58 are then opened and the noncondensable ~ gas is allowed to flow throughout the system. During operation ,, . ~ .
25 the pipe 57 serves to return any condensate of coolant 28 ~; from the expansion tank to the main liquid supply. Condensate of coolant 28 may form in expansion tank 33 due to 1uctuations n ambi:ent temperature. Pipe S7 is connected to the lowest , .. .
point of expansion tank 33 to mlnimize condensate hold up in ~he expansion tank.
i ., :
~ .
: .
5~55~
The embodiment oE E'IGURE 12 is similar -to -the er~odiment of FIGURE 11 except that the upper manifold 30, -the connec-ting pipe 55, the connecting valve 56 and drain valve 58 can ba dispensed with. It has been discovered that the transformer coolant can be pre-evacuated by heating and outgassiny the coolant prior to filling within the transformer such that the steps indicated earlier for FIGURE 11 are no longer required.
Once the transformsr coolant is completely outgassed particular care is taken to insure that the outgassed coolant does not reabsorb air in the final transformer filling stage.
Althou~h the percolation cooling system employing the heat pump of this invention is directed to applications involving medium and power transformers, this is by way of example only. The method and apparatus employed within the examples shown can be applied to cool other type of electrical apparatus providing the heat pump trans~er design of this invention can be incorporated within the electrical apparatus involved.
It should also be readily apparent that ~or certain ranges of am~ient temperatures and condensable coolants the noncondensable gas may be omitted wi-thout effecting -the operation of thé apparatus as described.
, ',~
:
,
Claims (6)
1. A method for percolation cooling of an electrical transformer comprising the steps of:
providing an air-tight container having a quantity of condensable coolant filling a portion of the container;
inserting at least one of the electrical apparatus within the container and in contact with a portion of the coolant said electrical apparatus having at least one duct extending through a portion of the apparatus for receiving said coolant;
adding a quantity of noncondensable gas to the container said noncondensable gas being of a predetermined pressure to cause the condensable coolant to boil at the operating temperatures of the electrical apparatus; and thermally outgassing the coolant prior to inserting within the container for removing trapped air.
providing an air-tight container having a quantity of condensable coolant filling a portion of the container;
inserting at least one of the electrical apparatus within the container and in contact with a portion of the coolant said electrical apparatus having at least one duct extending through a portion of the apparatus for receiving said coolant;
adding a quantity of noncondensable gas to the container said noncondensable gas being of a predetermined pressure to cause the condensable coolant to boil at the operating temperatures of the electrical apparatus; and thermally outgassing the coolant prior to inserting within the container for removing trapped air.
2. A self-propelled fluid cooling system for an electrical transformer comprising:
an air-tight container for housing the apparatus to be cooled;
a volume of condensable coolant within the container and covering at least a portion of the apparatus to be cooled;
a noncondensable gas occupying a volume within the container and having a pressure such that the coolant boils at the operating temperature of the apparatus to be cooled;
a heat exchanger for receiving the coolant in vaporized form and for returning the coolant in condensed form and at least one conduit extending through the apparatus for receiving a portion of the coolant in liquid form at one end and discharging the fluid in gaseous form at an opposite end said conduit extending above surface of the transformer for redistributing the coolant over the surface of the transformer.
an air-tight container for housing the apparatus to be cooled;
a volume of condensable coolant within the container and covering at least a portion of the apparatus to be cooled;
a noncondensable gas occupying a volume within the container and having a pressure such that the coolant boils at the operating temperature of the apparatus to be cooled;
a heat exchanger for receiving the coolant in vaporized form and for returning the coolant in condensed form and at least one conduit extending through the apparatus for receiving a portion of the coolant in liquid form at one end and discharging the fluid in gaseous form at an opposite end said conduit extending above surface of the transformer for redistributing the coolant over the surface of the transformer.
3. The cooling system of claim 2 further comprising a retainer around the perimeter of the top surface of the transformer for collecting and retaining the coolant on the transformer surface.
4. The cooling system of claim 2 further comprising a distribution tray proximate an end of said conduit for receiving coolant from the conduit and redistributing the coolant back over the transformer surface.
5. The cooling system of claim 4 wherein said distribution tray has a first plurality of perforations coextensive with the conduit and a second plurality of perforations adjacent said conduit for receiving the coolant in vapor form through said first perforations adjacent said conduit for receiving the coolant in vapor form through said first perforations and transmitting coolant in liquid form through said second perforations.
6. The cooling system of claim 3, further comprising at least one bus bar proximate an end of the conduit extension for receiving coolant from said conduit.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US84367677A | 1977-10-19 | 1977-10-19 | |
| US843,676 | 1992-02-28 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1119682A true CA1119682A (en) | 1982-03-09 |
Family
ID=25290695
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000313355A Expired CA1119682A (en) | 1977-10-19 | 1978-10-13 | Precolation cooled transformers |
Country Status (7)
| Country | Link |
|---|---|
| JP (1) | JPS5475033A (en) |
| CA (1) | CA1119682A (en) |
| DE (1) | DE2844884A1 (en) |
| ES (1) | ES473807A1 (en) |
| FR (1) | FR2406877A1 (en) |
| GB (1) | GB1595094A (en) |
| SE (1) | SE419486B (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP2665351A3 (en) * | 2012-05-17 | 2016-10-05 | Hamilton Sundstrand Corporation | Two-phase electronic component cooling arrangement |
Families Citing this family (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CA1180073A (en) * | 1980-05-28 | 1984-12-27 | Richard D. Gibbs | Vapor cooled electrical inductive apparatus |
| JPS58111307A (en) * | 1981-12-25 | 1983-07-02 | Toshiba Corp | Gas-insulated transformer |
| JPS59103318A (en) * | 1982-12-03 | 1984-06-14 | Mitsubishi Electric Corp | Apparatus for cooling machine or equipment |
| JPS59195810A (en) * | 1983-04-21 | 1984-11-07 | Mitsubishi Electric Corp | Vapor cooling type transformer |
| JPS60102716A (en) * | 1983-11-10 | 1985-06-06 | Mitsubishi Electric Corp | Evaporative cooling type gas insulating electrical apparatus |
| FI118397B (en) | 2004-02-13 | 2007-10-31 | Abb Oy | Liquid cooled choke |
| GB2549946A (en) | 2016-05-03 | 2017-11-08 | Bitfury Group Ltd | Immersion cooling |
| GB2550356B (en) * | 2016-05-16 | 2021-11-17 | Bitfury Group Ltd | Filter for immersion cooling apparatus |
Family Cites Families (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2505581A (en) * | 1945-03-26 | 1950-04-25 | Gen Electric | Means for drying gas in electrical apparatus |
| FR1095984A (en) * | 1953-02-19 | 1955-06-08 | Thomson Houston Comp Francaise | Advanced cooling system for electrical or electronic devices |
| GB759572A (en) * | 1954-08-06 | 1956-10-17 | Schachno Peisach Schotz | Improvements in and relating to the cooling of electric transformers |
| FR67553E (en) * | 1955-02-10 | 1958-03-14 | Thomson Houston Comp Francaise | Advanced cooling system for electrical or electronic devices |
| US3201728A (en) * | 1962-08-23 | 1965-08-17 | Westinghouse Electric Corp | Evaporative cooled inductive apparatus having cast solid insulation with cooling ducts formed therein |
| FR1406431A (en) * | 1964-09-03 | 1965-07-16 | Thomson Houston Comp Francaise | Improvements to evaporative cooling devices |
| US3887759A (en) * | 1972-11-29 | 1975-06-03 | Gen Electric | Evaporative cooling system employing liquid film evaporation from grooved evaporator surface and vapor push pump for circulating liquid |
| DE2432911A1 (en) * | 1974-07-09 | 1976-01-29 | Trafofit Gmbh | METHOD AND DEVICE FOR DRAWING WATER FROM DIELECTRIC LIQUIDS |
| US4011535A (en) * | 1976-07-09 | 1977-03-08 | General Electric Company | Vaporization cooled transformer |
-
1978
- 1978-05-12 GB GB19388/78A patent/GB1595094A/en not_active Expired
- 1978-09-29 ES ES473807A patent/ES473807A1/en not_active Expired
- 1978-10-13 CA CA000313355A patent/CA1119682A/en not_active Expired
- 1978-10-14 DE DE19782844884 patent/DE2844884A1/en not_active Withdrawn
- 1978-10-18 SE SE7810863A patent/SE419486B/en unknown
- 1978-10-18 JP JP12743578A patent/JPS5475033A/en active Pending
- 1978-10-19 FR FR7829748A patent/FR2406877A1/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP2665351A3 (en) * | 2012-05-17 | 2016-10-05 | Hamilton Sundstrand Corporation | Two-phase electronic component cooling arrangement |
Also Published As
| Publication number | Publication date |
|---|---|
| DE2844884A1 (en) | 1979-04-26 |
| GB1595094A (en) | 1981-08-05 |
| SE419486B (en) | 1981-08-03 |
| ES473807A1 (en) | 1979-10-16 |
| JPS5475033A (en) | 1979-06-15 |
| FR2406877A1 (en) | 1979-05-18 |
| SE7810863L (en) | 1979-04-20 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| EP0083154B1 (en) | Cooling apparatus for a gas insulated transformer | |
| US4145679A (en) | Vaporization cooled and insulated electrical inductive apparatus | |
| CA1119682A (en) | Precolation cooled transformers | |
| US4337569A (en) | Method of making integrally formed transformer cooling ducts | |
| US3626080A (en) | Means for circulating liquid coolants | |
| US2875263A (en) | Transformer control apparatus | |
| EP2966660B1 (en) | Immersion cooled toroid inductor assembly | |
| CN107430925B (en) | Fluid-insulated electrical apparatus and cooling method thereof | |
| US2849523A (en) | Electrical apparatus with vaporizable liquid coolant | |
| US4467305A (en) | Gas/vapor cooled electromagnetic induction machine | |
| US4173746A (en) | Vaporization cooled electrical apparatus | |
| US3264589A (en) | Transformer pockets for vaporized cooling | |
| US20120274430A1 (en) | Heat exchanger system for dry-type transformers | |
| EP0117349B1 (en) | Cooling apparatus for an electrical transformer | |
| US4129845A (en) | Vaporization cooled electrical apparatus | |
| US5688398A (en) | Device for filtering an electrically insulative and thermally conductive liquid medium and a power electronics unit incorporating a device of this kind | |
| US2774807A (en) | Vaporization-forced liquid cooled transformer | |
| US2947798A (en) | Cooling arrangement for electric apparatus | |
| JPS5860512A (en) | Evaporation cooling induction electric appliance | |
| JP2553157B2 (en) | Stationary induction equipment | |
| US2759987A (en) | Cooling electrical apparatus | |
| CA1111916A (en) | Vaporization cooled electrical inductive apparatus | |
| JPH0362291B2 (en) | ||
| JPS6014492B2 (en) | electromagnetic induction equipment | |
| JPS593906A (en) | Gas insulation transformer |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |