US2873954A

US2873954A - Heat exchanger for electric discharge tube

Info

Publication number: US2873954A
Application number: US523056A
Authority: US
Inventors: Protze Curt
Original assignee: Telefunken AG
Current assignee: Telefunken AG
Priority date: 1954-06-05
Filing date: 1955-07-19
Publication date: 1959-02-17
Anticipated expiration: 1976-02-17

Description

Feb. 17, 1959 c, PROTZE 2,873,954

HEAT EXCHANGER FOR ELECTRIC DISCHARGE TUBE Filed July 19, 1955 3 Sheets-Sheet 1,

INVENTOR CURT PROTZ E BY /ZQ/M PATENT AGENT Feb. 17, 1959 c: PROTZE 2,373,954

HEAT EXCHANGER FOR ELECTRIC DISCHARGE TUBE 7 Filed July 19, 1955 5 Shets-Sheet 2 INVENTOR PROTZE CURT avg Z5 PATE'NT AGENT Feb. l7,v 1959 HEAT Filed July 19, 1955 FIG. 6

FIG. 5

c. PRoTzE 2,873,954

EXCHANGER FOR ELECTRIC DISCHARGE TUBE 3 Sheets-Sheet 3 INVENTOR CURT PROTZE PATENT AGENT United States Patent HEAT EXCHAN GER FOR ELECTRIC DISCHARGE TUBE Curt Protze, Berlin-Siemensstadt, Germany, assignor to Telefunken G. 111. b. 11., Berlin, Germany Application July 19, 1955, Serial No. 523,056 7 Claims priority, application Germany June 5, 1954- 14 Claims. ('Cl. 257-250) This invention relates to the cooling of electron discharge tubes and has as its principal object the provision of cooling means which will produce the highest possible heat transfer from the anode of the tube to a circulating coolant while, at the same time, minimizing the likelihood of injury to the anode by local overheating due to faulty distribution of the heat exchange.

In the prior art vapor cooling arrangements, the'anode immerses with its whole outer surface into 'the liquid to be evaporized. This requires a water level of a height which remains constant under all operating conditions as well as the existence of a chamber as large as possible above the level of the liquid to be used for collecting steam and for separating said steam from the liquid particles taken along thereby. As in modern transmitters, especially in short or ultra-short wave transmitters, there are used tubes of a very small length, the above requirement is not compatible with the conditions to be observed for a proper electric operation. It is, therefore, a further object of this invention to avoid such a chamber above the effective part of the anode or at least to reduce the dimensions of the same considerably, without impairing the necessary separation of the vapor and liquid phase of the cooling means.

In the prior art vapor cooling arrangements, the initially very small and numerous steam bubbles combine to big ones on their way up to the level of the liquid. As a result of this they displace, and thereby move large quantities of the liquid surrounding the anode, causing considerable shocks in the whole tube system by their movements. It is, therefore, a further object of this invention to avoid such shocks as well as any secondary disadvantageous phenomena accompanied by same, such as disturbing noises, interfering modulation and mechanical damages. In the prior art vapor cooling arrangements, the zone of greatest turbulence, and thereby of the most favorable heat transfer, is on the surface of the liquid at some distance from the anode. Therefore, the cooling of the flange zone in which glass and metal are joined, and which is most important for the tube construction is critical in the above mentioned short wave or ultrashort wave-tubes. A very exact control of the level of the liquid absolutely necessary in such case is difiicult to carry out with a varying load. It is, therefore, a further object of the present invention to provide the most favorable cooling conditions, in particular at said critical flange zone, without providing special means to maintain the water level absolutely constant. The new apparatus can be put in operation under full load at a low water level. g

It is a still further object of this invention to provide a great number of channels on or in the wall of a vapor cooled anode of goodheat conductivity, said channels being closed all around, butopen at their two ends, and conveying the cooling agent. In order to facilitate the upward movement of the steam bubbles, it is recommended to arrange these channels in such a way that 4 other and being reciprocal to the respective masses.

"mitted to the cooling liquid from all sides.

2,873,954 Patented Feb. 17, 1959 hey are vertical, when the tube is in its operative position. As a rule they will run parallel to the axis of the electrode system.

It is well known in the art (see British Patent No. 473,797) to place the outer anode of a transmitting tube in the opening of a metal block with a good heat contact, the wall of said block being provided with numerous, for example 200, small longitudinal holes of about 3 mm. diameter each, through which cooling air is sucked. This device has not been generally accepted, because with compressed air or vacuum, it is possible to obtain an equivalent cooling action with a simpler arrangement. If now, in connection with the vapor cooling, a similar arrangement is used, this is done from a particular point of view. The result is unexpected and occurs only with vapor cooling. Since the cooling channel, as mentioned in the foregoing, is closed all around, heat is trans- Therefore, steam bubbles are formed not only on the side of the cooling channels adjacent to the discharge path and to the source of the dissipation heat, but all over the surface of said cooling channels. On account of the impulse axiom in mechanics, these rapidly forming steam bubbles, the growth of which is impeded in the channels, cause a strong upward flow. This well-known impulse axiom states that two masses between which an internal force is acting obtain velocities directed opposite to each In the present case, the internal force consists of the pressure exerted by a steam bubble. The one mass which is considerably smaller consists of the liquid column in the cooling channel above the steam bubble, whereas the non-evaporated liquid thereabove to form an emulcooling liquid.

sion of liquid and steam.- Since with water the steam volume is about 1600 times as large as the volume of the evaporated water, the emulsion leaves the upper ends of the channel at a considerable velocity. Due to the higher velocity of the emulsion and the whirling action in all cross-sectional planes caused by the heat fed radially from all sides, a considerable turbulance is obtained in the cooling channels, said turbulence greatly contributing to the heat transfer from the anode to the It has been found by tests than an anode with channels according to the invention is capable of drawing off more than three times as much heat as an anode provided with protuberances or ribs. It is a further advantage of such construction that the steam bubbles are formed in many small chambers, viz., the channels,

which are separated from one another, and therefore, can not cause powerful shocks which have been otherwise observed in the tube due to conglomeration. Thus, the vapor cooling means according to the invention operates considerably more quietly than the vapor cooling arrangements heretofore employed.

The above -vapor cooling device according to the invention makes is possible to provide an additional cooling action on the outer surface of the anode body containing' the cooling channels, thus allowing a further increase in the heat-load. It is a further advantage of the invention that the above mentioned ejection of the emulsion from the cooling channels starts during the initial evaporation with such violence that it is not necessary to exactly stabilize the water level, since the cooling J tity of liquid. This is generally true, because the anodes at their lower ends are longer than that part of them on which the electrons impinge and these inactive lower ends immerse into the cooling liquid. If necessary, the container of the cooling liquid can'be made still deeper, or the cooling channels may be extended over the effective part of the anode towards its bottom.

Finally, it is an advantage that the emulsion jet directed upwardly hits the flange zone which is inclined towards the longitudinal axis of the tube, whereby the jet is diverted. Due to the impact of the jet, a very favorable heat transfer is obtained in this zone so that it is sufliciently and reliably cooled. The diversion of the emulsion jet may occur at a place close to and above the point of its discharge from the channel so that, with a suitable shape of the flange zone, the water which is taken along is forced downwards into the water chamber of the cooling cup surrounding the anode. Since the water level, as mentioned in the foregoing, can be provided considerably below the upper extremity of the channel, enough space required for demixing of the emulsion will be available.

These and other objects and advantageous features of this invention will be apparent from the following detailed description and drawings, appended thereto, wherein merely for the purposes of disclosure non-limitative embodiments of the invention are set forth.

Fig. 1 shows a longitudinal section through a part of a tube according to this invention, said tube being mounted in a cooling cup designed to discharge the steam downwardly. This tube is adapted to be used in short wave transmitters.

Fig. 2 shows a cross section through the tube of Fig. 1 along the line 22.

Fig. 3 is a side view of another embodiment of this invention, which is partially shown in section.

Fig. 4 is a cross section through the embodiment of Fig.3 along the line 4-4.

Fig. 5 is a longitudinal section through a part of a tube which is a further embodiment of this invention.

Fig. 6 is a schematic illustration of a complete vapor cooling system according to the present invention.

In Figs. 1 and 2, the tube to be cooled comprisesran anode which is a part of the tube wall and comprises a thick-walled hollow cylinder 1 of copper or a copper alloy, said cylinder being sealed by means of a ring 2 of an iron-nickel-cobalt alloy to a glass body 3 closing the top of the vacuum vessel and having lead-ins for the electrodes surrounded by the anode, e. g., for the grid and the thermionic cathode. These electrodes, as they are of no importance for the invention, have been omitted in the drawing in order to simplify same. The anode. is closed at its lower end by a bottom 5. Close to its upper end the anode is provided with a flange 6 forming a right angle to the tube axis, said flange having at its outer edge a cross section, suited for mounting and sealing. The cylindrical part of the anode is provided with a plurality of cooling channels 7 parallel with respect to the tube axis. These cooling channels 7 are arranged concentrically to the tube axis, as shown in Fig. 2. The cooling channels are of circular cross section so that they can be easily prepared or drilled in the cylinder part 1. Bridge portions 8 are left between adjacent channels 7. The anode is shaped in such a way that an annular passage 9 is obtained between the flange 6 and the upper ends of the cooling channels 7. This passage 9 has an open side at the lower end of the flange 6 to discharge the cooling liquid.

The tube is inserted in a cylindrical cooling cup 10 which at its lower end has a bottom part 11 ending in the steam discharge pipe 12. A water feed pipe 13 is connected to and ends in the bottom part 11. The tube seats with the lower rim of the flange 6 on an upper ring 14, of the cooling cup 10, In order to prevent the steam or the water from escaping, there is provided a gasket 15 between the flange 6 and'the ring 14. If the weight of the tube itself is not sufiicient to provide the necessary sealing pressure, the later can be obtained by special clamping devices pressing the two parts together. The water feed pipe 13 actually ends in the liquid container 16, which is open at its top, and into which the anode 1 immerses. The upper rim of the container 16 has such a distance from the flange 6 and the ring 14 that the steam from the channels 9 can readily pass through the gap therebetween. Beneath the anode the chamber is divided into the two 'parts extending to the bottom of the container 16 by a partition 17 provided with apertures 18, at its lower end. The partition 17 may be a part of either the tube wall or the cooling cup and engages the anode along a circle of such diameter that all of the cooling channels are located on the inner side of this partition 17. In the upper part of the container 16 there are provided a few thin cylindrical sheet metal rings or anti-splashing plates 19 preventing the liquid from being atomized at the water surface 20. The steam passing from the cooling cup 10 through the pipe 12 is condensed in a condenser in a manner known per se and the liquid thus regained is returned to the cooling channels 7 via the water feed pipe 13 so that it may start another cycle. A water level control device, not shown in the drawing, assures that the water level 20 remains below the upper channel openings, while maintaining this level so high that at least half of the length of the anode hit by the electrons immerses into the liquid.

In operation, the anode 1 due to the dissipation heat formed therein becomes hot and transfers the heat to the liquid in the cooling channels 7 as well as to the liquid surrounding the anode jacket 21, whereby the liquid is heated to such an extent that steam bubbles are produced. While the bubbles formed on the surface of the anode simply move upwardly, the steam bubbles produced in the channels, due to their considerably increased volume compared to the volume of the evaporated liquid, will cause a violent upward movement of the steam-liquid mixture in the channels in accordance with the impulse axiom. Furthermore, due to the heat supplied radially from all directions, a considerable whirling action of the liquid will occur in each cross section of the channels. The emulsion current moving upwardly in the channels contains a greater'amount of steam in the upper cross sections and, after leaving the channels 7, this current violently hits the lower surface of the flange 6, cooling the latter most efliciently. At the same time, there occurs at the same place a considerable water separation, since the annular chamber 9 is shaped in such a way that the emulsion jet after being diverted is directed towards the water surface 20. To avoid excessive splashing, when the jet reaches the water surface, the latter is subdivided into small zones by the cylindrical anti-splashing-sheets 19. The steam, practically freed from water, is discharged from the evaporator chamber proper at a considerably reduced velocity via the gap between the upper rim of the water container 16 and the flange 6 and the ring 14, respectively, and is passed through the space between the cooling cup 10 and the water container 16 and through the steam discharge pipe 12 into the condenser.

Since the cooling means being a mixture of water and steam is forced upwardly in the cooling channels 7 with such a violence that it is discharged from the upper extremities of said channels as from an ejector, it is not absolutely necessary that the water level 20 in the cooling cup reaches the upper extremities of these cooling channels. Indeed, this water level 20 might be considerably lower without endangering the safe operation of the whole system.

The cooling cup as shown in'Fig. 1 is designed in such a way that the outer wall of the cylindrical jacket 21 of the anode 1 is in contact with the cooling water so that the heat is removed also from this place. Exp m have shown that it is possible to increase the. eificlency of the cooling system about'20% depending on the level of the water.

As to the dimensioning of the internal diameter: and

the number of the cooling channels 7, various consideratrons are important. For the cooling channels 7 such internal diameter is used that the steam bubbles moving upwardly bounce as often as possible against the wall of the cooling'channels in order to prevent the steam bubbles from permanently adhering thereon. These considerations are similar to those usually applied in designing pipes of high-pressure water tube boilers. The cooling channels 7 are to be spaced from each other such distance that the bridges 8 betweentwo adjacent cooling channels have a cross section sufficiently large to conduct the heat from the inner side of the anode to the outside also via those sides of the cooling channels which are not facing the longitudinal axis of the anode, thereby causing evaporation at such places. I In the present embodiment, the internal diameter of the anode is 80 mm., the axial length of the anode surface hit by electrons is about 50 mm., the number of cooling channels is 30, and their internal diameter is 6.5 mm. With such design the anode is capable to receive a dissipation power of about 60 kw. without overheating.

In the embodiment of Figs. 3 and 4, a cylindrical anode 22 is provided on its outer surface with longitudinal ribs 23 which are suitably tapered towards the outside, i. e., having an approximately trapezoidal cross section. A hollow metal cylinder 24 is secured, for example, by

soldering, to said ribs, whereby cooling channels 25 of a trapezoidal or triangular cross section are obtained.

While in the embodiment of Fig. 1 the steam from cooling cup is discharged downwardly, the embodiment of Fig. 5 provides for an upwardly directed steam discharge. Corresponding parts in Fig. 5 are marked with the same reference numbers as used in Fig. l. The cooling water enters through the cooling pipe 26 ending in the bottom of the cooling cup 10. A part of the cooling water flows upwardly in the cooling channels 7, while another part of the cooling water streams through the apertures 18 of the cylindrical partition 17 into the chamber surrounding the jacket 21 of the anode. The same actions around the anode are taking place as described with reference to the embodiment of Fig. l. The mixture of water and steam forced upwardly from the cooling channels is diverted in the ring-shaped space 9, whereby a considerable portion of the water is separated from the mixture and drops on the water surface 30 at the place where ring-shaped anti-splash sheets 31 are provided.' In this embodiment the diameter of the cooling cup 10 is considerably larger than that of the anode jacket 21, e. g., twice as large, thereby providing above the water surface 30' a sufliciently large chamber 32 in which the steam becomes quiescent and separates furtheramounts of water. The steam then leaves this chamber 32, through an aperture in the top or flange 14 of the cooling cup, said aper ture leading via an upwardly tapered nozzle 27 to the steam discharge pipe 28. The nozzle 27 extends over a certain length into the steam discharge pipe, thus forming between the nozzle 27 and the pipe 28 a ring-shaped chamber 29 in which the Water condensed in this steam discharge pipe 28 can be collected. The water collected at 29 is returned via drain pipe 30 to the cooling cup 10.

In the schematical illustration of Fig. 6 a complete vapor cooling system according to the invention is shown. Similar as in the arrangement of Fig. 1, a tube R is mounted with its anode A in a cooling cup T, to which the cooling water is fed via a feed pipe F and an anti-electrolysis means E, known per se. The steam is removed via a steam discharge pipe D. The steam is passed through a water separator W in form of a coiled tube, and then enters the condenser K. The liquid recovered therein flows into the return water pipe L and then into the feed pipe F into which also flows the water recovered in the water separator via a pipe F For the purpose calledfloat' vessel N is provided which has a float S- adapted to open a valve V leading to a reserve water tank B, when the water level in the float vessel falls below the required level. The water level between the float vessel and the cooling cup is balanced via a pipe F while pipe D serves to equalize the steam pressure between the cooling cup and the chamber of the float vessel above the water level. The water accumulating at the lowest point of the steam discharge pipe D is collected in a container B, and is conveyed from this container B via a pipe F to the water pipe F; by means of an immersion P driven by a motor M.

Although in accordance with the provisions of the patent statutes this invention is described as embodied in concrete forms and the principle of the invention has been explained together with the best modes in which it is now contemplated applying that principle, it will be understood that the elements and combinations shown and described are merely illustrative and that the invention is not limited thereto, since alterations and modifications will readily suggest themselves to persons skilled in the art without departing from the true spirit of the invention or from the scope of the annexed claims.

I claim:

1. A structure for cooling a closed vessel having upwardly extending walls by means of a vaporizable liquid comprising, a liquid container surrounding said vessel and extending upwardly in spaced relation with respect to said walls, said container having an open top and having a liquid entrance therebelow through which the level of said liquid is maintained, said walls having a plurality of upwardly extending enclosed liquid channels open at their tops and bottoms and partially immersed in said liquid with the open bottoms located below the level of said liquid so that vapor formed in said channels must travel upwardly to escape therefrom.

2. In a structure as set forth in claim 1, said channels comprising a plurality of spaced drilled holes of diameter-small enough that the upward escape of the vapor causes turbulent and rapid flow therein.

3. In a structure as set forth in claim 1, said channels comprising a plurality of spaced outwardly disposed ribs, and a metallic enclosure overlying said ribs and attached along substantially the full length of the outer surface thereof by heat conductive metal bonding.

4. In a structure as set forth in claim 1, a support for said vessel comprising a partition attached to the bottom of said vessel and extending downwardly therefrom outside the open bottoms of said channels, the partition resting in the container and including said liquid entrance, and having apertures communicating with the liquid in the container outside said partition.

5. In a structure as set forth in claim 1, said vessel having at its upper end an outwardly disposed flange spaced from the top of said container and spaced from and overlying the open tops of said channels, the vapor escaping from the open tops of the channels impinging upon the underside of said flange and being deflected back against the surface of said liquid in the container.

6. In a structure as set forth in claim 5, said vessel comprising the metal anode of an electron tube, and said tube having a glass envelope bonded to said anode in the vicinity of the upper surface of the flange, the vapor impinging on said flange serving to cool the glass-tometal bond.

7. In a structure as set forth in claim 6, said channels extending over at least that portion of the anode to which the electrons within the tube flow.

8. In a structure as set forth in claim 5, the lower surface of said flange having a downwardly opening arcuate groove therein, the groove extending over the open tops of the channels to redirect downwardly the vapor discharging thereinto.

9. In a structure as set forth in claim 5, a cup surrounding said container and sealed against said flange, the top of said container terminating below said flange and leaving a chamber in which said vapor may collect, and an exit duct communicating with the chamber'in said cup for leading off said vapor.

10. In a structure as set forth in claim 9, said exit duct being located in the bottom of said cup whereby both vapor and liquid may be led 01f from the cup.

11. In a structure as set forth in claim 1, said vessel having at its upper end an outwardly disposed flange sealing against the top of said container and forming therewith a vapor-collecting chamber, said flange overlying the open tops of said channels and being spaced therefrom whereby the vapor escaping from said open tops will impinge upon the underside of said flange and be deflected back against the surface of said liquid.

12. In a structure as set forth in claim 11, an exit duct communicating with said chamber and leading upwardly therefrom to a condenser and liquid cooling system, a condensed-liquid trap in said exit duct, and a passage leading from said trap to said container and terminating below said liquid level.

13. In a structure as set forth in claim 12, said trap comprising a tapered nozzle as the entrance to said exit duct and having a larger diameter at its lower end than 8 at its upper end; the upper end of the nozzle being smaller in diameter than the exit duct and extending upwardly therein'to to form an intervening annular trap connected with the upper end of said passage, condensed liquid returning to said container through the passage from the trap.

14. In a structure as set forth in claim 11, a series of splash plates projecting above said liquid level and adapted to reduce the splash of the vapor and liquid impinging on the liquid in said container.

References Cited in the file of this patent UNITED STATES PATENTS 1,947,179 Acheson Feb. 13, 1934 1,991,065 Scism 2. Feb. 12, 1935 2,011,647 Mouromtsefi et al. Aug. 20, 1935 2,060,519 Mouromtseif Nov. 10, 1936 2,181,366 Edwards et a1. Nov. 28, 1939 2,440,245 Chevigny Apr. 27, 1948 2,513,828 Usselman et a1. Jul 4, 1950 2,636,141 Parker Apr. 21, 1953 FOREIGN PATENTS 504,253 Belgium July 14, 1951 1,060,761 France Jan. 12, 1955 (Addition to No. 62,367)