US2605377A - Heat exchange method and apparatus - Google Patents

Description

y 1952 w. L. KAEHNI ET AL HEAT EXCHANGE METHOD AND APPARATUS 2 SHEETS-SHEET 1 Filed July 15. 1947 V DIIIIBIIDIIDQDBDD lljl 1/ 1 l Tj q.

July 29, 1952 Filed July 15,

2 SHEETS-SHEET 2 I111 ///I l/ Ill/ll I l/ ll/I/l/I/ 0 a an 1 I I I 1 1 1 i m H H 1 1 H I 1 1 1 I H H ,U H I 1 l I I I I 0 I I J U 1 1 1 J u 1 1 u I 1 H 1 1 1 H l I I H H n n I 1 1 H U 1 I I 1 1 1 u n r V FRANK J.KAEHNI Patented July 29, 1952 HEAT EXCHANGE METHOD AND APPARATUS William L. Kaehni and Frank J. Kaehni, Cleveland, Ohio, assignors to Metal Carbides Corporation, Youngstown, Ohio, a corporation of Ohio Application July 15, 1947, Serial No. 760,974

18 Claims. 1

The present invention relates to heat exchange methods and apparatus and, more particularly, to the use of an electrostatic field for increasing the rate of heating or cooling of fluids and for increasing the amount of heat transferable to or from the fluid under a given set of conditions.

We have found that by the use of an electrostatic field formed by electrodes connected to a high potential unidirectional source of electrical energy the rate of transfer of heat from a solid body to a fluid or from a fluid to a solid body or from one fluid to another fluid can be appreciably increased and that the amount of heat transferable from one to the other under a given set of conditions can be increased. We have also found that by proper use and application of such an electrostatic field the amount of heat which can be made available for transfer to or from the solid body or fluid under certain circumstances can be materially increased. As a consequence, processes and apparatus involving an exchange of heat can be simplified and the productivity or efficiencies thereof appreciably increased. Moreover, wherever dissipation of heat or transfer thereof from one fluid or solid body to another is desired in order to obtain or maintain high operating efliciencies, such, for example, as in the operation of motors, transformers, radio transmitting equipment, and the like, our invention may be utilized and appreciably improved results obtained.

In the heating of fluids such as-oils, water, other liquids, air and other gases, and in the cooling thereof, by the usual methods involving a transfer of heat directly from the heating source or through some convenient medium, the rate of heat transfer, as well as the total available heat from the heating means employed, is quite important and in many industrial heat exchange installations these factors have been of a limiting nature. In many instances these factors have made it necessary to increase the total amount of equipment required for carrying out a particular operation and have resulted in drastically limiting the capacity of the equipment. This is particularly true in the heating or cooling of those fluids, such as oil, which are not good conductors of heat. This is also true where batch processes are employed for heating fluids or solids which are in suspension or emulsion in a fluid. Frequently it is necessary to utilize lengthy heating cycles or expensive stirrers in such processes with the result that production costs are materially increased.

In many diiferent types of industrial apparatus the problem of maintaining parts or all of the apparatus at a proper operating temperature is quite acute. If not maintained at a proper temperature a loss of efliciency results. For example, electrical motors, transformers and generators must be cooled to prevent overheating with a corresponding loss in efliciency. Also, in radio transmitting equipmentit is desirable to cool the vacuum tube anodes to get best results. Gas turbines and internal combustion engines, likewise, must be cooled to prevent general or localized overheating in use. We have found that, by the use of a unidirectional high potential electrostatic field in the manner more specifically described hereinafter in connection with heat exchange apparatus, cooling of such apparatus can be effected so as to maintain proper operating temperatures and, hence, greater efficiency. In fact, in the case of electric motors, for example, we believe that sufficient cooling can be obtained by the use of our invention to provide higher ratings for motors of any given size and characteristics.

In other types of industrial processes and equipment such as furnaces and other apparatus for annealing, normalizing or otherwise heat treating steels and other metals and apparatus for heating or cooling plastics and other materials, where it is necessary to put heat into or extract heat from a. liquid or solid, our invention also may be utilized with the result that the heating or cooling can be accomplished more efficiently and more effectively.

In view of the limitations imposed by low heat transfer on various industrial processes and equipment involving an exchange of heat between fluids or between a fluid and a solid body or between solid bodies, various efforts have been made to increase the rate of heat exchange as well as the total heat transferred and many expedients have been adopted. In this connection, the prior workers have followed the more or less conventional practices. However, the present invention constitutes a completely new approach to the problem of heat transfer. It provides for an induced electro-motion within the fluid constituting one of the elements of the heat ex change system. I

In accordance with our invention, we apply an electrostatic field to a fluid in the heat exchange system while the fluid is being heated or cooled. The fluid may be the medium to be heated or cooled or it may be merely the transfer medium for effecting a transfer of heat between two or more solid bodies or between a solid body and another fluid.

By applying an electrostatic field to the fluid while it is being heated or cooled or acting as a transfer medium, a continuous motion of charged particles, molecules or atoms from a surface of one polarity through the fluid to a surface of opposite polarity is provided. A unidirectional current, preferably ordinary direct current, of high potential is used to create the electrostatic field between suitably positioned electrodes. In some applications of our invention one or both of the electrodes may be separate parts of the apparatus; but in most applications one or both of the spaced electrodes for providing the unidirectional electrostatic field constitute a part or parts of the apparatus utilized for heating, cooling, carrying, conducting or supporting the fluid.

By the use of a unidirectional high potential the particles, molecules or atoms are moved between the electrodes. They may move the entire distance from one electrode to the other or they may move only a part of the distance, depending on the extent of the movement required to obtain and give up their charges. This not only provides a more rapid and a greater heat exchange but also provides a more rapid equalization of the temperature of the fluid body itself.

In view of this charging of the particles of the fluid and the resultant electro-motion between the electrodes our invention may be used to advantage where a mixing of hot and cold fluids or a mixing of fluids at the same temperature is desired. It may also be applied in the making of emulsions, solutions or suspensions of liquids and solids.

Where our invention is applied to the heating of a dielectric fluid, such as oil, air, gases of various types, kerosene, alcohol, resins and fluid plastics flowing through a chamber, such as a tube, the electrostatic field may be applied in such a way that the heating member, which may be a heated surface or a heated wire, forms one of the electrodes, the other electrode being positioned with respect to the fluid so that the electrostatic field Will traverse the fluid itself. Likewise, in the cooling of such fluids the surface or member to which the fluid is to give up its heat may be one of the electrodes and the other electrode may be placed in such a way with respect to the fluid that the electrostatic field will traverse it and impart what we call an electro-motion to the particles, etc. However, we have found that an increase in the rate of heating or cooling of the fluids by this electrostatic means can be accomplished, even though the heating or cooling element or surface is not used as one of the electrodes for the establishment of the electrostatic field. For example, where a fluid is being heated by contact with a heating element or surface, the electrodes can be spaced within the fluid and the heating or cooling means positioned between the electrodes so that the electro-motion imparted to the particles, molecules or atoms of the fluid will cause them to move from the one electrode to the other and in the course of said movement come in contact with or in close proximity to the heating or cooling means. However, best results are obtained where the heating or cooling surface or element is one of the electrodes for forming the electrostatic field.

By way of illustration, our invention can be readily applied to the heating of oils and the like as they pass through suitable conduits. A resistance wire extending longitudinally through the tube carrying the fluid can be used for heating it as it moves through the tube. This wire may be an ordinary Nichrome resistance wire and may be connected to a source of alternating current for supplying the heat. If the conduit or tube is of metal or some other electrically conductive material, it may be utilized as one of the electrodes and the heated wire for supplying the heat to the fluid can be utilized as the other electrode. However, if the conduit or tube containing the fluid is relatively non-conductive, the resistance wire can still be used as the one electrode and a metal electrode on the inner periphery of the tube or conduit can be utilize as the other electrode. As the oil or other fluid passes through the tube, it is heated by the resistance element.

When the electrostatic field is applied in the manner just mentioned, the rate of heat transfer from the heating element to the fluid is appreciably increased, the increase in many instances being as high as 1100%. Moreover, the oil or other fluid is heated more uniformly, due to the electro-motion imparted to the fluid by the electrostatic field. In other apparatus illustrated diagrammatically herein, similar increases in the rate of heat exchange have been obtained. In addition, we have obtained an increase of from 40-80% in the total amount of heat transferred.

While, as stated above, it is not necessary that the resistance wire forming the heating element be utilized as one of the electrodes, we have found that it is desirable to use it as an electrode wherever possible because a greater increase in heat transfer can be obtained than when separate, spaced electrodes, which form no part of the regular heat exchange system, are used. Moreover, due to the fact that there is a greatly increased rate of heat transfer from the heating element an appreciably greater amount of current can be supplied to the resistance heating element. In other words, the current carrying capacity of a given heating element is appreciably increased as a result of the increased rate of heat exchange.

By the use of our invention the rate of heat transfer as well as the amount of heat which can be obtained from a surface at a given temperature can be increased. In other words, where an electrostatic field is used the amount of heat transferable, as well as the rate of transfer from a surface of a given temperature, can be increased. This permits. the operation of various types of apparatus at lower temperatures without any sacrifice in the heat transferred. Another advantage arising out of our invention is that the transfer of heat can be controlled or regulated by merely changing the voltages employed.

Although our invention is especially useful in processes involving heat transfer, it will be apparent from what has already been stated that it is not limited thereto and may be utilized where uniformity of temperature in or mixing of a fluid body is desired. The application of a direct current high potential to the fluid moves the particles from adjacent the one electrode to a point adjacent the other electrode, and this continuous motion of the charged particles mixes the fluid thoroughly.

While the specific illustration of our invention set forth above relates to a heating operation,

our invention is not limited thereto but may be used where cooling is desired. The increased heat transfer provided by our invention makes it possible to electrostatically cool a gas or a solid body and, hence, our invention can be used where the primary objective to be accomplished is the cooling of a fluid or a solid body as distinguished from those heat exchange processes in which the primary objective is the heating of a fluid or a solid; Furthermore, our invention is not limited to processes and apparatus wherein the heat is applied electrically but may be used in heating operations where the heat is supplied by other means such as by combustion of fuels or by preheating of a fluid or solid prior to the application of the electrostatic field.

Nor is our invention limited to processes and apparatus wherein the chamber, solid body, or conduit carrying or contacting the fluid is an electrical conductor; The chamber, solid body, conduit, etc. contacting the fluid may be a dielectric material, such as glass. The fluid utilized, however, must have sufiicient dielectric properties to permit the establishment of an electrostatic field therein.

In the accompanying drawings, we have shown diagrammatically, for purposes of illustration only, several ways in which our invention may be utilized.

In the drawings:

Figure 1 is a vertical section through apparatus which may be used for heating a body of liquid;

Figure 2 is a vertical diametral section through apparatus whichalso may be used for the heating of a body of liquid;

Figure 3 is a diagrammatic sectional viewshowing the manner in which our invention may be utilized in the heating of a fluid during its passage through a tube;

Figure 4 is a diagrammatic sectional view showing another way in which our invention may be applied to the heating of a fluid during its continuous passage through a tubular chamber;

Figure 5 is a diagrammatic sectional view showing another way in which our invention may be applied to the heating of a fluid as it passes through a tubular chamber;

Figure 6 is a sectional View taken along the line VI-VI of Figure 5; t

Figure '7 is a diagrammatic sectional view showing another way in which our invention may be applied to the heating of a batch of fluid in a container;

Figure 8 is a diagrammatic sectional view illustrating the application of our invention to a process which involves the heating of one fluid as it passes through a tube or the like, and also the transfer of heat from that fluid through a solid body to another fluid;

Figure 9 is a view partly in section and partly in elevation showing the application of our invention applied to the heating of a fluid by means of a series of fuel burners as the fluid is passed through a tube; and

Figure 10 is a section taken along the line X-X of Figure 9.

In the embodiment diagrammatically illustrated in Figure 1, the liquid 2 is contained in a chamber 3, which is open at the top and closed at the bottom. This container is made of glass, although, as will be apparent, it can be made from any suitable material since the container itself does not form one of the electrodes. The

heat for heating the liquid is applied through an electric resistance heater 4 which extends upwardly through the bottom of the container through the bushed opening 5. The leads 6 which are connected to the heater are suitably connected to a heating current which, in general will be alternating current. The electrostatic field in this embodiment is applied to the liquid by utilizing the resistance heater 4, which is preferably metal, as one of the electrodes and a metal thermometer tube I as the other electrode. This metal thermometer tube 1 extends upwardly through the bottom of the container through the hushed opening 8. The leads 9 which are connected to the electrodes are connected at their other ends to a source of high potential direct current. In the drawing the heater is illustrated as the positive electrode, although it is immaterial whether this heater or the thermometer tube is the positive electrode. The thermometer tube 1 is of metal and is connected by a conduit Hi to an indicating member ll so that the increase in the temperature of the liquid can be determined readily. I

The liquid to be heated in this embodiment may be oil, alcohol, turpentine, glycerine, paraffine, various petroleum products, linseed oil, shellac, varnish, or any other liquid having dielectric characteristics.

The embodiment illustrated in Figure 2 is likewise suitable for batch heating a liquid. The chamber I5, in which the liquid 2 is heated, is of a metal having electrical conductivity. The heat for raising the temperature of the liquid is provided by a resistance element 1-6 which surrounds the side wall of the container. The resistance element I6 is connected by suitable leads I! to a source of heating current, which may be either alternating or direct current. The container itself forms one of the electrodes for impressing an electrostatic field on the liquid. The

other electrode in this embodiment is a metal thermometer bulb I 8' which extends into the liquid through a bushed opening iii in the bottom thereof. The container and the metal tube are connected b leads 20 to a suitable unidirectional high potential electric source. In order to determine the extent to which the liquid is heated, an indicator 2| is provided for the thermometer and it is connected to the thermometer bulb by the conduit 22. The thermometer employed is the ordinary commercial liquid-type thermometer. In this embodiment, the high potential electrostatic field causes the particles of the fluid to be charged and to pass back and forth between the positive and negative electrodes, with the result that the rate of heating is materially increased. Also, the equalized ultimate temperature is higher when the electrostatic field is impressed on the liquid than when the heating current alone is employed.

The embodiment in Figure 3 diagrammatically illustrates the application of our invention to a process in which a fluid, which may be air or gas or any other dielectric, passes continuously through a tube or other suitable enclosure. In this embodiment, the fluid passes through the tube 25. A heating wire 26 extends axially through the tube and is in contact with the fluid. The heating wire is preferably a rela-- tively flat Nichrome wire, although, as will be apparent, any other suitable electric resistance elementmay be employed. This wire is connected by leads 2! to a source of alternating current. The tube 25, inthis embodiment, is metal 7 and is one of the electrodes in the electrostatic field. The other electrode is the wire 26 which, as stated, also functions as the resistance heater. The tube 25 and the Wire 26 are connected by leads 28 and 29, respectively, to a unidirectional source of high potential.

The embodiment shown in Figure 4 is likewise suitable for the heating of a dielectric fluid as it passes continuously along the source of heat. In this embodiment, the fluid passes through the tubular chamber 30, which is preferably of metal, and it is heated by the resistance heating element 3| which extends spirally around the outer periphery of the tube. The heating element is connected b leads 32 to a source of alternating current. As in the embodiment shown in Figure 3, the side wall of the chamber itself forms one of the electrodes. In this embodiment, the tube 3!] is connected by a lead 33 to the positive side of a source of unidirectional current of high potential, while in Figure 3, the metal tube 25 is illustrated as being connected to the negative side of the high potential source. .As is stated above, equally ood results are obtained, irrespective of polarity, but a unidirectional current, as distinguished from an alternating current, is required.

In Figure 4 the negative side of the high potential source is connected by a lead 34 to a longitudinally extending electrode 35 positioned axially of the tube. This electrode is in the form of a relatively flat Nichrome wire. Round wire may be used, but we have found that somewhat better results are obtained where a flat wire with rounded edges is used.

The embodiment shown in Figures and 6 is likewise suited for the heating of a continuously moving dielectric fluid. The fluid passes through the tubular chamber 40 which may be of metal or a dielectric, such as glass. The source of heat is a longitudinally extending wire 4| which extends axially of the tubular container. The wire is connected to a source of alternating current by means of leads 42.

In this embodiment, neither the tube nor the heated wire 4| is an electrode in the electrostatic field. Spaced electrodes 53 and 44 are provided within the tube 40. Any suitable form of electrode which is in contact with the fluid may be used but, as is illustrated, where the chamber is in the form of a cylinder, the electrodes are preferably in the form of curved plates positioned on opposite sides of the tube. The electrodes should be positioned so that charged particles in passing from one electrode to the other will come in contact with or in close proximity to the source of heat. The electrodes are connected to a suitable unidirectional high potential current by leads 45.

The embodiment shown in Figure '7 is for batch heating of a dielectric fluid. In this embodiment, the chamber containing the liquid is in the form of a tube 50 which is open at the upper end and which is closed at the lower end by a stopper 5|. The heat for heating the fluid is supplied by means of a resistance element 52 which extends vertically through the chamber. At its upper end the heating element 52 is connected to a lead 53 which is connected to one side of a source of alternating current. The lower end of the resistance element is connected by a suitable lead 54 to the other side of the alternating current source. The stopper 5! is preferably made of an insulating material, such as rubber, and the resistance element passes through an opening 55 which extends through the stopper. The container may be of metal or any suitable substance, since it does not form one of the electrodes in this embodiment. The electrodes are the resistance heating element 52 and a metal tube 56 which is of a smaller diameter than the tube 58, but which nevertheless closely approximates the diameter of the tube 50. This metal tubular electrode and the resistance element are connected to a unidirectional high potential source by leads 5'! and 58, respectively.

In the embodiment shown in Figure 8, several heat transfers are efiected. A resistance element 60 extends axially of a tube Bl through which a fluid may be passed in the direction of the arrow. An outer tube 62 surrounds the tube 6! and provides a chamber for a fluid passing therethrough in the same direction as or the opposite direction to the fluid in the pipe 6|. In order to increase the rate of heat exchange between the resistance element 88 and the fluid passing through the tube El, the heating element 653 forms one electrode and the tube itself forms the other. The wire 60 and the tube 61 are connected to a source of direct current through leads 63. Where it is desired to increase the rate of heat transfer between the tube 5! and the fluid passing between it and the tube 62, the tube 62 can be connected by a lead 54 to one side of a source of unidirectional high potential current, so that the tube 6| and the tube 62 will each form an electrode for an electrostatic field impressed on the fluid passin through the tube 62. As is illustrated in the drawing, in an embodiment of this character the outer tube and the resistance heating element should be of the same polarity, the tube Bi being of opposite polarity.

As will be apparent, the inner tube 5! of this illustrative embodiment may be heated in various ways. For example, instead of heatin it by electrically heating the fluid passing through it, the fluid may be heated before entering the tube 6|. In passing through the tube it will give up its heat to the tube which in turn will heat the fluid within the outer tube or chamber 52 and that fluid may give up its heat to the outer tube or to anything positioned within that tube or chamber. In this way, our invention may be applied to the ordinary tube type annealing or heat treating furnace for treating metal sheets or the like placed therein.

The embodiment of our invention shown in Figures 9 and 10 illustrates our invention as applied to a heating operation in which heat is supplied by gas or other fuel burners. The tube ll carries the fluid to be heated and is surrounded by one or more circular burners 12 havin small ports 53 spaced around the inner periphery thereof. Gas or other suitable fuel is supplied to each burner 12 by an inlet M. The wire or rod extending through the tube forms one electrode and is connected by a lead 76 to the positive side of the source of high potential. The tube forms the other electrode and is connected by a lead 11 to the negative side of the high potential source. If desired the burners also may be connected to the positive side of the high potential source. In this way an electrostatic field is established through the fluid passing through the tube and one is established between the flames and the tube. Both fields increase the amount of heat transferred and the rate of transfer.

Where our invention is employed the increase in heat, exchange is greatest when the distance between the oppositely charged surfaces is small, such as, for example, from a fraction of an inch to'several inches, although a greater spacing of the electrodes may be employed with effective results. However, under such circumstances, higher direct current potentials are required in order to get the best results. Voltages of from 5,000 to 20,000 produce excellent results on medium sized tubing of two to three inches in diameter. It will be understood, however, that any suitable voltages can be utilized, depending on the nature of the apparatus to which the invention is applied.

By the term high potential as used herein, we mean potentials of the order of those normally used for the creation and maintenance of electrostatic fields and, more specifically, a potential in excess of about 1500 volts per inch of spacing between the electrodes utilized for forming the field. With potentials of this magnitude, advantageous results can be obtained, whereas with potentials of low magnitude no effective results can be obtained.

The increase in rate of heat transfer obtainable by our invention, of course, will depend upon the conditions under which it is used. We have found, for example, that we can step up the rate of heat transfer in apparatus of the character described above to 1100%, depending on the conditions employed.

While we have described and diagrammatically illustrated several embodiments of our invention, it will be readily apparent to those skilled in this art that it may be utilized for (a) heating or cooling of fluids and solid bodies in heat .exchangeprocesses and apparatus, (b) cooling motors, generators, transformers, gas turbines, internal combustion and other types of engines and the like, cooling vacuum tube anodes and other parts of radio transmitting equipment, (d) heating or cooling metals, plastics and other materials in annealing, normalizing, heat treating, melting, and other types of heating furnaces or chambers, (e) refrigerating apparatus, (f) mixing various types of fluids or mixing fluids and finely divided materials, and (g) for cooling lubricating oils for engines such as those in ships where special marine coolers are now required. It may be employed or embodied in this and various other ways within the scope of the appended claims.

In our copending application, Serial No. 641,398, filed January 15, 1946, we have described and claimed the use of an electrostatic field in connection with heating methods and apparatus and, more particularly, in connection with flames, electric arcs and other heat generating media. The present application is related to said copending application and, in respect of the broad general disclosure of said application, may be considered as a continuation-in-part thereof.

We claim:

1. The method of effecting an exchange of heat between two bodies, at least one of which is a dielectric fluid, which comprises bringing the fluid into contact with the other body when they are at different temperatures and with at least one electrode adapted when charged to maintain a high potential unidirectional electrostatic field through the fluid while it is in contact with the other body, said field having a potential gradient in the fluid in excess of about 1500 volts per inch, and maintaining said field through the fluid while it is in contact with the other body.

10 2. The method of effecting an exchange of heat between two bodies, at least one of which is a dielectric fluid, which comprises bringing the fluid into contact with the other body when they are at different temperatures and with an electrode, and maintaining a high potential unidirectional electrostatic field through the fluid and between said other body and said electrode while the fluid is in contact with said other body and said electrode, said field having a potential gradient in the fluid in excess of about 1500 volts per inch.

3. The method of effecting an exchange of heat between two bodies, at least one of which is a dielectric fluid, which comprises bringing the fluid into contact with the other body when they are at different temperatures and with at least two electrodes adapted to maintain an electrostatic field through the fluid when it is in contact with the other body and maintaining a high potential unidirectional electrostatic field between .the electrodes and through the fluid when it is in contact with said other body, said field having a potential gradient in the fluid inexcess of about 1500 volts per inch. I

4. The methodof efiecting an exchange of heat between a solid body and adielectric fluid which comprises bringing the fluid into contact with the body when they are at different temperatures and with at least one electrode adapted when charged to maintain a high potential unidirectional electrostatic field through the fluid when it is in contact with the solid body and maintaining said field through the fluid while it is in contact with the solid body, said field having a potential gradient in the fluid inexcess of about 1500 volts per inch.

5. The method of effecting an exchange of heat between an object and a dielectric fluid which comprises bringing the fluid into contact with the object when they are at different temperatures and an electrode spaced from, the object and maintaining a high potential unidirectional electrostatic field through the fluid and between the object and the electrode, said field having a potential gradient in the fluid in excess of about 1500 volts per inch.

6. The method of effecting an exchange-of heat between an object and a dielectric fluid which comprises heating the object, bringing the fluid into contact with and passing it over both the object and an electrode spaced from the object and maintaining a high potential unidirectional electrostatic field through the fluid and between the object and the electrode, said field having a potential gradient in the fluid in excess of about 1500 volts per inch.

'7. A method of heating a dielectric fluid which comprises passing the fluid in contact with a heated surface and with at least one electrode spaced from said surface and adapted when charged to maintain a high potential unidirectional electrostatic field .through said fluid and subjecting the fluid to such a field while it is in contact with said surface and said electrode, said field having a potential gradient in the fluid in excess of about 1500 volts per inch.

8. A method of heating a dielectric fluid which comprises the steps of passing the fluid in contact with a heated surface and with an electrode spaced from said surface and subjecting the fluid as it passes in contact with said surface and said electrode to a high potential unidirectional electrostatic field between the heated surface and said electrode, said field having a potential 11 gradient in the fluid in excess of about 1500 volts per inch.

9. A method of heating a dielectric fluid which comprises passing the fluid in contact with a heated surface and with at least one electrode spaced from said surface and adapted when charged to maintain a high potential unidirectional electrostatic field through said fluid and subjecting the fluid to such a field while it is in contact with said surface, said field having a potential gradient in excess of about 1500 volts per inch.

10. The method of increasing the heat transfer between a solid and a dielectric fluid which comprises bringing the fluid into Contact with the solid when they are at different temperatures, establishing an electrostatic field, by means of a high potential unidirectional source, between the solid and an electrode in contact with the fluid, said field having a potential gradient in excess of about 1500 volts per inch.

11. The method of increasing the heat transfer between a solid and a dielectric fluid which comprises bringing the fluid into contact with said solid when they are at different temperatures and at least two electrodes spaced from and on opposite sides of said solid and maintaining a high potential unidirectional electrostatic field through said fluid between said electrodes, said field having a potential gradient in excess of about 1500 volts per inch.

12. Apparatus for exchanging heat between a dielectric fluid and a container therefor comprising a casing at a temperature difierent from the temperature of the fluid and adapted to contain said fluid and to serve as one electrode in a high potential electric circuit, a second electrode in said casing and spaced therefrom, and means for maintaining a high potential unidirectional electrostatic field between said electrodes, said field having a potential gradient in excess of about 1500 volts per inch.

13. Apparatus for exchanging heat between a dielectric fluid and a container therefor comprising a casing at a temperature different from the temperature of the fluid and adapted to contain said fluid and to serve as an electrode in a high potential circuit, a second electrode in said casing and spaced therefrom, and means including said electrodes for establishing a unidirectional high potential electric field through the fluid having a potential gradient in excess of about 1500 volts per inch.

14. Apparatus for the exchange of heat between two dielectric fluids having different temperatures comprising two casings, one positioned within the other and each adapted to contain one of the fluids and means for establishing a high potential unidirectional electric field between the two casings, said field having a potential gradient in excess of about 1500 volts per inch.

15. Apparatus for the exchange of heat between two dielectric fluids having diiferent tem- 12 peratures comprising two casings, one positioned within the other and each adapted to contain one of the fluids, an electrode within the inner casing and means for establishing high potential unidirectional electric fields of potentials in excess of about 1500 volts per inch between the electrode and the inner casing and between the two casings.

16. The method of effecting an exchange of heat between a solid object and a dielectric fluid, which comprises passing the dielectric fluid when at a different temperature than the solid along and in contact with the solid object and an electrode spaced from the object, and maintaining a high potential unidirectional electrostatic fleld through the fluid between the object and the electrode, said field having a potential gradient in the fluid in excess of approximately 1500 volts per inch.

17. In the method of controlling the flow of heated media between a heat source and an adjacent body, the steps comprising providing a heat source and establishing and maintaining an electrostatic field having a potential gradient in excess of about 1500 volts per inch between the heat source and the adjacent body to which heat is to be applied while using the heat source as the positive electrode for creating the electrostatic field.

18. In the method of controlling the flow of heat between a heat source and an adjacent body, the steps comprising providing a source of heat and establishing and maintaining a low energy unidirectional electrostatic field having a potential gradient in excess of about 1500 volts per inch between the heat source and the adjacent body while using the heat source as the positive electrode for establishing the electrostatic field, said field being of such character that no current except that incident to the maintenance of the field passes between the heat source and said body.

WILLIAM L. KAEHNI. FRANK J. KAEHNI.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 732,616 Burgess June 30, 1903 1,473,347 Hoskins Nov. 6, 1923 1,835,557 Burke Dec. 8, 1931 1,854,475 Littlefleld Apr. 19, 1932 1,980,521 Hahn Nov. 13, 1934 1,980,821 Palueif Nov. 13, 1934 2,018,434 Ballentine Oct. 22, 1935 2,264,495 Wilner Dec. 2, 1941 2,362,889 Darrah Nov. 14, 1944 FOREIGN PATENTS Number Country Date 429,352 Great Britain May 28, 1935

Images