US3823872A

US3823872A - Nozzle for use in hot liquid ejector pumps, and related process

Info

Publication number: US3823872A
Application number: US00301171A
Authority: US
Inventors: O Frenzl
Original assignee: SNECMA SAS
Current assignee: Safran Aircraft Engines SAS
Priority date: 1971-11-19
Filing date: 1972-10-26
Publication date: 1974-07-16
Anticipated expiration: 1991-07-16
Also published as: IT975765B; JPS4863308A; DE2256590A1; FR2161288A5

Abstract

The efficiency of conventional hot-liquid nozzles of the type normally used to create the driving jet in ejector pumps is increased by eliminating at least a part of the predominantly liquid boundary layer normally found on the inner surfaces of such nozzles. The boundary layer can be eliminated by providing within the nozzle a gas layer in contact with the inner surfaces of the nozzle or by withdrawing from the nozzle liquid making up the boundary layer. This is accomplished by providing in the nozzle wall, means such as orifices, slits or porous sections which permit the transmission of a fluid such as a gas or liquid through the wall. Thus gas can be injected through such means from a source external to the nozzle to form the gas layer within the nozzle, or boundary layer liquid present within the nozzle can be withdrawn from the nozzle. The result of such procedures is to displace, and/or minimize the formation of the liquid boundary layer. The gas can be injected through the nozzle walls at various locations along the length of the nozzle. One technique for physically removing from the nozzle liquid making up the boundary layer is to provide a thin peripheral slit in the nozzle which communicates with a low pressure zone outside the nozzle. The pressure differential causes at least some of the liquid forming the boundary layer to flow out of the nozzle through the slit.

Description

United States Patent 1191 Frenzl July 16, 1974 NOZZLE FOR USE IN HOT LIQUID EJECTOR PUMPS, AND RELATED PROCESS [75] Inventor: Otto FrenzLDammarie-les-Lys, France [73] Assignee: Societe Nationale DEtude Et De Construction De Moteurs DAviation, Paris, France [22 Filed: hoe'r. 26, 1972 [21] Appl. No.: 301,171

[.30] Foreign Application Priority Data FOREIGN PATENTsoR APPLICATIONS 125 ,723

Primary Examiner-Allen N. Knowles Assistant ExaminerMichael Y. Mar Attorney, Agent, or Firm-Lawrence W. Flynn, Esq.

. HOT

PRESSURIZED WATER 4/l9l9 Great Britain 239/4193 5 7] ABSTRACT The efficiency of conventional hot-liquid nozzles of the type normally used to create the driving jet in ejector pumps is increased by eliminating; at least a part of the predominantly liquid boundary layer nor- 1 mally found on the inner surfaces of such nozzles. The boundary layer can be eliminated by providing within the nozzle 21 gas layer in contact with the inner surfaces of the nozzleor by withdrawing from the nozzle liquid making up the boundary layer. This is accomplished by providing in the nozzle wall, means such as orifices, slits or porous sections which permit the transmission of a fluid such as a gas or liquid through A the wall. Thus gas can be injected through such means from a source external to the nozzle to form the gas layer within the nozzle, or boundary layer liquid present within the nozzle can be withdrawn from the noz-i zle. The result of such procedures is to-displace, and- /or minimize the formation of the liquid boundary layer. The gas can be injected through the nozzle walls at various locations along the length of the nozzle.

One technique for physically removing from the nozzle liquid making up the boundary layer is to provide a thin peripheral slit in the nozzle which'communicates with'a low pressure zone outside the nozzle. The pressure differential causes at least some of the liquid forming the boundary layer to flow out of the nozzle through the slit.

28 Claims, 5 Drawing Figures DRlVING JET HOT paessumzeo 'WATER DRIVING'JET PATENTEU 3,823,872 sum 1 of 3 24 25 STEAM 27 F |G.|- DRlVlNG JET HOT 7a PRESSURIZED 26 l WATER I" I PRESSURIZED I HOT WATER DRIVING JET HOT PRESSURIZED WATER 7- HOT PRESSURIZED WATER STEAM 32 I;

PAIENTEU JUL 1 6 ran ME? 2 0F 3 F'IGB.

FIG.4.

- ST EA M ,DRIV ING JET HOT STEAM BOILER HOT GASES OF' BOILER PRESSURIZED WATER FEED E TO NOZZLE PUMP Pmmiuwue w 3.823.872

SHEET 3 0F 3 FIG.5. 'Q

LIQUID .58 52 30 DRIVING JET HOT PRESSURIZED WATER HOTT PRESSURIZED WATER DRIVING JET BOUNDARY LAYER I LIQUID l NOZZLE FOR USE IN HOT LIQUID FJECTOR PUMPS, AND RELATED PROCESS The present invention allows the nozzles to operate effectively in liquid ejector pumps'using moderate pressure feed liquid or to produce a drive jet of higher energy using thehigh. pressure liquid feeds normally employed in such nozzles.

CROSSREFERENCES TO RELATED APPLICATIONS Applicant claims the priority date of his corresponding French Pat. application No. 71/41528 filed in France on Nov. 19, 197 l pursuant to the provisions of 35 U.S.C. paragraph] 19, for all the subject matter of this application which is common to said French application.

BACKGROUND OF THE INVENTION The present invention relates to an improved nozzle of the converging-diverging type commonly used in ejector pumps in which the working fluid of the nozzle is a hotliquid under pressure. Normally, the hot liquid is water although other liquids can also be used. This invention further relates to an improvement in the process normally carried out in such nozzles which renders the process more efficient.

The details of hot-water nozzles and theiruse in ejector pumps are well known. For example, it is known to drive air through supersonic wind tunnels by means of hot-water ejectors. Such arrangements aredescribed in Applicants prior US. Pat. Nos. 2,914,941 and 3,049,005 and their French counterpart patents. A

' more detailed publication pertaining to the use of hotwater ejectors in wind tunnels is found in the brochure entitled S.N.E.C.M.A. Hot Water Drive for Wind Tunnels, put .out in 1959 by Marc Wood International, lnc., 30 Rockefeller Plaza, New York, N.Y,. Wind tunnel arrangements of this type have already been produced. v v

Similar hot-water ejectors have been used for engine test facilities as detailed in Applicants article inthe Journal of Spacecraft, Vol. 1, No. 3, May-June 1964, pp. 333-338 and in desalinization processes as illustrated in French Pat. No. 1,595,843, of which Applicant is a co-inventor.

In conventional hot-water ejector pumps, a part of the hot water under pressurevaporizes, as it flows through the driving nozzle of the pump, and the liquid residue is simultaneously cooled, atomized into very small droplets and accelerated. The driving jet emerging from the nozzle has a high content of liquid (typically 70-80 percent or more) and therefore a speed which is less than the jet of the same energy which issues from a conventional steam-fed nozzle; the mixing of this relatively slow driving jet with the induced air or 2 mentioned publications operate in gusts in order not to require too high an installed power. The hot water intended for the ejector in such systems is removed during a short time interval from ahot water storage vessel; consequently, there is no difficulty in storing water under high pressure and saturation temperature in such a system.

However, future applications requiring continuously operating hot-water ejectors are now contemplated, for

example, in such processes as sea water-desalinization,

gas purificationor dust removal. For such applications it is normally necessary to install high pressure hot water boilers, the use of which is at present not common. This results in substantial investment expenses.

It is therefore an object of this invention to provide new techniques and apparatus for improving the efficiency of hot-liquid nozzles so that moderate pressure liquid feeds can now be effectively employed, thereby making the above me'ntioned applications more feasiother fluid drawn in by the pump therefore produces a smaller loss of energy.

It has been found in practice that for equal driving" energy a hot-water ejector has an 'efficiency greater than that of a steam ejector when the driving nozzle is fed with hot water at high pressure (for instance of the order of about atmospheres) but that the efficiency of the ejector becomes very poor if the driving nozzle is fed with hot water at moderate pressure (for instance of the order of about 30 atmospheres or less). The supersonic wind tunnels described in the above- .ble by eliminating the need for high pressure boilers.

It is another object of this invention to provide new techniques and apparatus for improving the present efficiency of hot-liquid nozzles to thereby increase the energy content of the driving jet when the high pressure liquid feeds presently used are available.

These and other objects of this invention will be apparent to one skilled in the art from a consideration of this entire disclosure, including the accompanying drawings.

1 SUMMARY OF THE INVENTION These objectives are broadly accomplished, in accordance with the present invention, by providing a process and means for effectively eliminating at least a portion of the predominantly liquid boundary layer normally found on the inner surfaces of a hot-liquid nozzle. In general, this is accomplished by providing means formed .in the wall of such nozzles which allow a fluid to be transmitted through the nozzlewall. Such the nozzle and in other cases it flows out of the nozzle,

but the flow is always through the nozzle wall.

In certain aspects of the invention, elimination of the boundary layer is accomplished by introducing within the nozzle additional energy beyond that normally obtained in the operation of the nozzle so that the boundary layer is eliminated while simultaneously making an energy contribution to the nozzle. More specifically, elimination of this boundary layer can be accomplished in a variety of ways. For example, it has been found that if a gas is introduced into the nozzle interior in such-a way thatthe added gas is maintained in contact with the wall or innerjsurface of the nozzle, the liquid boundary-layercan be at least partially and in some cases substantially eliminated and the nozzles efficiency increased. The added gas used is normally a material. identical to that flowing through the nozzle. Since cordingly, this aspectof the invention will be more specifically described hereinbelow in terms of steam as the gas, although it is to be understood that other gases can also be used;

In one embodiment, the gas from an external source is injected, preferably in superheated state, though a porous section in the wall of the nozzle. The gas injection creates a gaseous film or layer on the inner surface of the nozzle which can dislodge at least a portion of a pre-existing liquid boundary layer or minimize the formation of a boundary layer. The injectedgas preferably comes from the boiler which supplies the driving liquid for the nozzle. In another embodiment, the gas in a substantially dry condition is injected through orifices in the nozzle wall downstream of an obstruction located either in the neck of the nozzle or upstream of the neck. It will be appreciated that in the above embodiments, the gas eliminates at least a portion of the boundary layer while simultaneously making an energy contribution to the nozzle.

The boundary layer can also be at least partly eliminated by means which do not rely upon the formation of a gas layer-within the nozzle. For example, it can be eliminated by physically withdrawing from the nozzle, through a channel in the nozzle wall, at least a portion of the liquid forming the boundary layer. In one embodiment of this aspect of the invention, the diverging portion of the nozzle is provided with a thin peripheral slit which provides communication between the interior of the nozzle and a chamber maintained at a pressure lower than that in the nozzle. The pressure differential aids in drawing liquid from the inner surfaces of the nozzle through the slit into the low pressure chamber and out of the nozzle.

Although the invention is in no way limited by any scientific theories or hypotheses, one may attempt to explain the advantageous effects of the improvements defined above in the following manner. It may be thought that the low efficiency of the ejector pump is due essentially to the fact that the expansion of the hot water in the nozzle is insufficient to cause an abundant liberation of driving steam, particularly as a boiling delay phenomenon can take place in the nozzle. As almost all of the hot water thus remains liquid in the nozzle, it is probable that its acceleration by the small amount of driving steam is unsatisfactory and that its flow against the wall of the nozzle also produces relatively high friction losses which are believed to be associated with the pressure of the predominantly liquid boundary layer on the wall. Even though a portion of the liquid feed is vaporized'in the nozzle, the vast majority of the feed remains in a liquid state. As this liquid comes into contact with the nozzle walls, it creates a boundary layer thereon. It also seems likely that some of the vapor formed in the nozzle, upon striking the relatively cool walls of the nozzle, may condense to add to the liquid boundary layer. Finally, it is probable that other relatively substantial energy losses take place in the pump upon the acceleration of the induced fluid by the driving jet containing an excessive proportion of the liquid boundary layer which has been decelerated on the wall of the nozzle. It is therefore plausible that a relatively small contribution of steam in contact with the wall of the nozzle substantially reduces the losses, on the one hand by eliminating, or at least minimizing the extent of, the liquid boundary layer thereby decreasing friction losses, and on the other hand by increasing the quantity of driving steam in a relatively large proportion. In that aspect of the invention which the thermodynamic efficiency of the hot liquid nozzles.

For example, US. Pat. No. 3,399,511 to Paul L. Geiringer discusses the friction of the inner surfaces of hot water nozzles and recognizes the adverse effect of the 'friction losses produced by'these surfaces upon the thermodynamic efficiency of the nozzle. Geiringer suggests adding heat to the nozzle to solve the problem. The added heat is said to reduce the friction along the nozzle surfaces and to evaporate liquid formed on such surfaces. Geiringer adds the heat by several different techniques all of which differ significantly from the present invention because none of them relies on the transmission of a fluid through the nozzle wall. In one embodiment,. Geiringer heats the nozzle surfaces by wrapping an electrical resistance wire around the exterior of the nozzle. In another embodiment, the wire is replaced by tubing through which a heating fluid is circulated. In yet another embodiment Geiringer provides the nozzle with an; external jacket through which a heating fluid is circulated. What all of Geiringers embodiments have in common is that the nozzle walls are heated by heating means external to the nozzle. Geiringer does not contemplate supplying energy directly to the nozzle by directly injecting steam into the nozzle through the nozzle wall. Nor does Geiringer contemplate actually removing liquid from the nozzle interior through the nozzle wall. It can be appreciated that in contrast .to Geiringers approach, the present invention is distinguishable in that the liquid boundary layer or friction layer in the nozzle is eliminated by an energy addition to the nozzle which is a direct addition in the sense thatthe source of the energy (steam, for example) is injected directly into the nozzle, as opposed to Geiringers indirect energy contribution wherein the energy addition is transmitted into the nozzle by heat transfer through the nozzle wall from an energy source (for example, the electrical resistance wire) outside the nozzle.

Applicants French Pat. No. 1,465,707 points out the advantages of maintaining a liquid film on the inner 1 wall of the mixing tube-diffuser section used to decelerate the mixture resulting when the driving jetemerging from a hot-water nozzle contacts a gas such as air. The present invention, however,'is concerned with the elimination of a liquid layer and its replacement by a gas layer which creates less friction than the liquid layer, and with the presence of such layers at the surfaces of a hot-water nozzle andnot in a separate piece of equip ment downstream of the nozzle. The objective of the present invention is to improve nozzle efficiency not the efficiency of the mixing tube-diffuser section.

The invention will now be described in greater detail in conjunctionwith the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an axial section through an improved hotwater nozzle of this invention.

FIG. 2 is-a view similar to FIG. 1, showing another embodiment of the invention.

I FIG. 3 is a half section along the line 33 of FIG. 2.

DESCRIPTION OF THE PREFERRED I EMBODIMENTS In the embodiment of FIG. 1, the liquid boundary layer is eliminated by the injection of steam through a porous section in the nozzle wall downstreamof the neck of the nozzle. Referring to FIG. 1, the nozzle is formed of a conduit consisting of three parts, a first part 17 forming the converging cone 2a, the neck 3a and an upstream portion of short length 18 of the diverging cone 4a; a second part 19 forming the downstream zone 20 of said diverging cone; and a third porous intermediate part 21 which forms an intermediate zone 22 of the diverging portion and which is present between part 19 and part 17. The latter is extended downstream by a tubular portion 23 surrounding the porous intermediate part 21 and terminating in a flange 24 which is fastened to a flange 25 of part 19. A conventional needle 5a is adapted along the XX'axis of the nozzle to adjust the flow rate through the nozzle.

The porous intermediate part 21 is provided on the outside with annular chambering 26 which forms within the tubularportion 23 a space which is connected to a source of steam by a conduit 27. This source of steam is typically a steam boiler which also supplies the hot water under pressure 6a which feeds the nozzle, in accordance with an arrangement similar to that which'will be described hereinbelow with reference to FIG. 4. The hot water under pressureaccelerates and expands in the nozzle (which causes its partial vaporization, as already explained). Due to this expansion, the pressure in the zone 22 of the diverging cone is less than the pressure in the boiler so that steam is drawn into zone 22 through the conduit 27, fills the space 26 and passes through the pores of the part 21 to form a layer or film of steam in contact with the portion 22 of the diverging cone. The steam does not cool down substantially during this travel; it suffers a loss of head upon passage through the pores of the part 21 and arrives, expanded, in the diverging cone. The steam which forms the layer is therefore in superheated state. This layer of steam is present in the zone 22 of the diverging cone which large quantities of water have'a tendency to strike, This layer tends to move along the wall of the nozzle into the remaining portions of diverging cone 20. The film of steam minimizes the tendency for the water striking the nozzle walls to form a liquid boundary layer in the diverging portions of the nozzle.

. portion 28 and a downstream portion 29 connected by a cylindrical portion 30 provided with longitudinal ribs 31 which are also distributed circumferentially and 6. which serve as guide for a cylindrical portion of the needle 5b. In the wall of the conduit 1b, around these ribs 31, there is provided an annular chamber 32 which is fed with steam through a conduit 33 and communicates with the inside of the nozzle via a plurality of orifices 34, each of which discharges radially into the cylindrical portion 30 of said nozzle just downstream of the ribs 31. Stated differently, the orifices 34 discharge upstream of the neck of the nozzle in the wake of the obstruction formed by the ribs 31.

The hot water which feeds the nozzle, as indicated by the arrows 6b, is supplied by a boiler which is shown schematically at 35 in FIG. 4. This boiler comprises a lower header 36, a tube nest 37 heated by the hot gases 38 of the boiler, and an upper header 40. The lower header and the tube nest are filled with water which rises-up to the level N in the upper header. This level is maintained constant by a water feed 39 controlled by a conventional automatic feed device (not shown in the drawing); The boiler produces saturated steam in a known manner; the .water and the steam which are at the'level, N in the header 40 are at the same pressure (the pressure of the boiler) and at the same temperature (saturation temperature).

The nozzle has its axis XX located at a height h below the level N, and it is fed with hot water through a conduit 41 which extends from the bottom'of the header 40. The pressure of the water at the entrance to the nozzle (expressed in height of water) is therefore equal to the pressure of the boiler plus h. The conduit 33 which feeds the annular chamber 32 with steam extends from the top of the upper header 40 and is provided with a regulating valve 42.

Referring to FIGS. 2 and 3, it will be understood that the hot water which enters the nozzle in thedirection shown by the arrows 6b flows into the portion 28 of the converging cone and then passes through the channels 43 present betweenthe ribs 31 and discharges at the speed W into the annular space 44 located downstream of these ribs, between the needle 5b and the cylindrical portion 30 of the wall of the nozzle. The value of this speed W depends on the value of the pressure of the steam arriving from the boiler in the orifices 34. If the valve 42 is wide open, this pressure is practically equal to that of the boiler so that the speed W is practically equal to V 2gb, 3 being the acceleration of gravity; the steam which passes through the orifices. 34 into the space 44 then forms downstream of each rib 31 a small pocket of saturating steam of equal pressure with the water. If one reduces the steam feed by means of the valve 42, the pressure in the chamber 32 and the orifices 34, and therefore also in the space-44, will be lowered so that the speed W will increase; the pressure of the hot water in the channels 43 will therefore drop locally to below the vapor tension of the hot water, but a delay in boiling will generally occur and the water will start to vaporize in the space 44in contact with the superheated steam coming from the orifices 34. The steam thus produced will mix uniformly with the steam introduced through the orifices 34 and will be driven,

downstream along the walls of the nozzle.

It is therefore. seen that it is possible by means of the valve 42 to control the proportion of water and steam flowing through the nozzle to form at the outlet of the nozzle the driving jet 7b (FIG. 4) which serves as the inductor jet for drawing a fluid at 45 and delivering it at 47.

into the pump 46 FIG. S'illustrates anembodiment of the invention in which a steamlayer in contact with the nozzle surfaces is not relied upon for elimination of the liquid boundary layer. In FIG. 5, parts having the same function as in FIG. 1 are designated by the same reference numbers provided with the suffix 0. Referring to FIG. 5, the diverging cone 4c is similar to cone 4a in FIG. 1 except that it has been shortened at its discharge end. Cone 4c isenclosed in a generally cylindrical hollow jacket 51 which'is rigidly affixedto cone 4c through a plurality of spaced ribs 52 which extend radially from cone 4c.

The downstream ends of walls 53 of jacket 51 are provided with thickened portions 54 which are curved inwardly and in an upstream direction to form at the downstream end of jacket 51 a conduit 55 having a vides communication between the interior of said diverging cone and the hollow chamber 58 surrounding the conduit. Chamber 58 is connected to a vacuum or other low pressure source by conduit 59 or other means to create in chamber 58 a pressure lower than that in the diverging portion of the nozzle. This pressure differential causes boundary layer liquid on the inner surfaces of cone 40 to flow through the slit created by space 57 and into chamber 58 from which it is removed through conduit 59. Space 57 must be kept sufficiently thin to prevent any substantial amount of the driving jet 70 produced in the nozzle from being diverted into chamber 58 in response to the pressure differential.

The liquid withdrawn in this manner forms at least a portion of. the liquid boundary layer in the nozzle. To

facilitate and guide the removal of the liquid, the inner downstream surfaces of cone 4care tapered outwardly as at 60 while the adjoining upstream surfaces of con duit 55 aretapered inwardly as at 61. The curved portions 54 of jacket 51 direct the liquid removed from cone 4c in a generally upstream direction throughthe channels between spaced ribs 52 to exit conduit 59. The physical removal of this liquid from the nozzle results in an increase of the average value of the velocity of the driving jet and hence an increase in nozzle efficiency. I I

It should, be noted that in those embodiments which rely upon formation of a gas layer in the nozzle, a sub-.

stantial increase in output can'be obtained by an addition of gas at a rate of about 1 to percent that of the working liquid flowing through the nozzle. The arrangement of FIG. 1 permits a high contribution of energy; the porous part 21 makes it possible to remove from the boiler an amount of steam equal to a few percent by weight of the hot water introduced into the nozzle; the layer of superheated steam injected against the wall 22 is thicker and its contribution to the increase of the thermodynamic efficiency may be higher. It is the embodiment of FIGS. 2 and 3 which permits the largest contribution of energy, the orifices 34 making it possible to inject an amount of steam which may, for instance, reach up to 15 percent the rate of the hot water introduced into the nozzle. In this embodiment, the

steam content of the flow increases uniformly along the nozzle. z

The specific embodiments discussed above and other detailed information set forth herein, are illustrative only and such modifications and alteratio'nsthereof as would be apparent to one skilled in the art are deemed to fall within the scope of the invention as defined by the claims appended hereto.

What is claimed is:

1. In a nozzle of the type used in hot water ejector systems comprising a converging portion and a diverging portion interconnected by a neck portion and adapted to partially "evaporate and atomize a hot fluid fed to the converging portion of said nozzle under pressure and in the liquid state, improved means for eliminating at least a portion of the predominantly'liquid boundary layer ordinarily'formed on the inner surfaces of said nozzle, comprising means formed in the wall of said nozzle which provide a conduit for the transmission of a fluid through said wall.

2. The nozzle of claim 1 wherein said means formed in said nozzle wall comprises orifices for injecting a gas from an external source into said nozzle through the wall of said nozzle. v

3. The nozzle of claim 2 wherein, said orifices are in the wall of the converging portion of. the nozzle.

4. In a nozzle of the type used in hot water ejector systems comprising a converging portion and a diverging portion" interconnected by a .neck portion and adapted to partially evaporate and atomize a hot fluid fed to the converging portion of said nozzle under pressure and in the liquid state, improved means for eliminating at least a portion of the predominantly liquid boundary layer ordinarily formed on the inner surfaces of said nozzle, comprising means formed in the wall of the nozzle at a point other than the neck portion of the nozzle which provide a conduit for the transmission of a fluid through said wall.

5. In a nozzle of the type used in hot water ejector systems comprising a converging portion and a diverging portion interconnected by aneck portion and adapted to partially evaporate and atomize a hot fluid fed to the converging portion of said nozzle under pressure and in the liquid state, improved means for elimithe wall of said nozzle and'into said nozzle.

6. The nozzle of claim-5 wherein saidporous section is in the wall of the diverging portion of the nozzle'.

7. In a nozzle of the type used in hot water ejector I systems comprising a converging portion and a diverging portion interconnected by a neck portion and adapted to partially evaporate and atomize a hot fluid fed to the converging portion of said nozzle under pressure and in the liquid state, improved'means for eliminating at least a portion of the predominantly liquid boundary layer ordinarily .formed on the inner surfaces of said nozzle, comprising a thin peripheral slit in the nozzle wall for withdrawing at least a part of the liquid comprising the boundary layer from said nozzle through said slit.

8. The nozzle of claim 7 wherein said peripheral slit is in the wall of the diverging portion of said nozzle.

9. The nozzle of claim 1 wherein said means formed in said nozzle wall comprises means for injecting a gas from an external source into said nozzle through the wall of said nozzle to provide in said nozzle a gas in contact with the wall of the nozzle.

10. In a nozzle of the type used in hot water ejector systems comprising a converging portion and a diverging portion interconnected by a neck portion and adapted to partially evaporate and atomize a hot fluid fed to the converging portion of said nozzle under pressure and in the liquid state, the improvement comprising means for forming on the inner surface of said nozzle in contact with said liquid a layer of said fluid in its gaseous state, said layer being formed by gas injected into said nozzle from a gas source external to the nozzle.

11. In a nozzle of the type used in hot water ejector adapted to vertically exaporate and atomize a hot fluid under pressure and in the liquid state introduced into said converging portion, the improvement which comprises a porous-section in said nozzle in contact with the interior of said nozzle, an enclosure surrounding said porous section and having a chamber therein communicating with said porous section, and means for supplying said fluid to said chamber, in its gaseous state, whereby said gaseous fluid permeates said porous section and creates on the inner surface of said porous section a layer of said gaseous fluid.

12. The nozzle of claim 11 wherein said porous section forms an intermediate part of the diverging portion of said nozzle.

13. In a nozzle of the type used in hot water ejector systems comprising a converging portion and a diverging portion interconnected by a neck portion and adapted to partially evaporate and atomize a hot fluid under pressure and in the liquid state introduced into said converging portion, the improvement which comprises a converging portion comprising an upstream and downstream converging cone separated by an intermediate section, means disposed in said intermediate section for creating a flow obstacle to the stream flowing through the intermediate section, and means for injecting said fluid, in its gaseous state, through the walls of said cylindrical section downstream of said obstacle creating means.

14. The nozzle of claim 13 wherein said means for creating an obstaclecomprises a plurality of ribs extending radially into said intermediate section from the wall of said intermediatesection, and wherein said means for injecting said fluid comprises a plurality of 10 tion and containing therein a hollow chamber, said chamber communicating with said slit, and means for creating in said chamber a pressure lower than that prevailing in said nozzle, whereby liquid on the inner surface of said nozzle is drawn out of said nozzle through said slit into said chamber.

16. The nozzle of claim 15 wherein said means form ing said slit comprises two separate axially aligned and cooperating portions forming said diverging portion of said nozzle, and means for maintaining said axially aligned portions in spaced relationship to form said slit between the adjoining edges of said portions.

17. The nozzle of claim 15 wherein said slit is a thin peripheral slit.

18. In a nozzle of the type used in hot water ejector systems comprising a converging portion and a diverging portion interconnected by a neck portion and adapted to partially evaporate and atomize a hot fluid under pressure and in the liquid state introduced into said converging portion, the improvement comprising means for providing on the inner surface of the nozzle,

from means other than the vaporization of the liquid feed tothe nozzle caused by the divergingportion of the nozzle, and from a gas source external to the nozzle, a gaseous fluid in contact with the inner surface of the nozzle which is capable of making an energy contribution to the nozzle.

19. In a method which comprises introducing into the converging portion of a nozzle of the type used in hot water ejector systems comprising a converging portion and a diverging portion interconnected by a neck portion a hot fluid under pressure and in the liquid state and partially evaporating and atomizing said fluid in said nozzle, the improvement which comprises eliminating from the inner surfaces of the nozzle at least a portion of the predominantly liquid boundary layer normally associated with said surfaces by providing in the wall of said nozzle means for transmitting a fluid through said wall, and then passing a fluid through said means.

20. The method of claim 19 wherein said means comprises orifices in the nozzle wall and wherein said fluid is a gas which is injected through said orifices into said nozzle from a gas source external to the nozzle.

21. The method of claim 19 wherein said means comprises a porous section in the nozzle wall and wherein said fluid is a gas which is injected through said porous section into said nozzle from a gas source external to orifices in the wall of said intermediate section, said orifices communicating with manifold means from which said fluid, in its. gaseous state, is supplied to said orifices, said orifices being disposed to inject said fluid into the wake created by said ribs.

15. In a nozzle of the type used in hot water-ejector systems comprising a converging portion and a diverging portion interconnected by a neck portion and adapted to partially evaporate and atomize a hot fluid under pressure and in the liquid state introduced into said converging portion, the improvement which comprises means forming a slit in the diverging portion of 7 said nozzle which provides communication between the interior and exterior of said diverging portion, a

jacket enclosing at least a portion of said diverging porthe nozzle.

22. The method of claim 19 wherein said means comprises a peripheral slit in the nozzle wall and wherein the fluid is liquid present in the nozzle which passes from the interior to the exterior of the nozzle through said slit.

23. The method of claim 19 wherein said boundary layer is eliminated by providing (1) a hollow chamber enclosing the diverging portion of the nozzle and (2) a thin peripheral slit in said diverging portion which communicates with said chamber, and creating in said chamber a pressure less than that prevailing in said diverging portion whereby liquid is withdrawn from said nozzle through said slit.

24. The method of claim 19 wherein said boundary layer is eliminated by passing a gas, from a gas source external'to the nozzle, through said fluid transmission means in said nozzle wall toform in said nozzle a gaseous layer and maintaining said gaseous layer in contact 1 1 with the inner surface of said nozzle, said gaseous layer further characterized in that it creates an energy addition to the nozzle.

25. The method of claim 19 wherein said hot fluid is water.

26. In a method which comprises introducing into the converging portion of a nozzle of the type used in hot water ejector systems comprising a converging portion and a diverging portion interconnected by a neck portion, a hot fluid under pressure and in the liquid state, and partially evaporating and atomizing said fluid in said nozzle, the improvement which comprises providing in the diverging portion of said nozzle a porous section and injecting said fluid in its gaseous state, through said porous section and into said nozzle to form on the inner surface of said nozzle a gaseous layer of said fluid.

27. In a method which comprises introducing into the converging portion of a nozzle of the type used in hot water ejector systems comprising a converging portion and a diverging portion interconnected by a neck portion, a hot fluid under pressure and in liquid state, and partially evaporating and atomizing said fluid in said nozzle, the improvement which comprises providing a converging portion comprising two converging cones separated by an intermediate section, said section containing a plurality of ribs extending into said intermediate section and a plurality of orifices upstream of said ribs, and injecting into said intermediate section through said orifices said fluid, in its gaseous state, to form on the inner surface of said nozzle a layer of said gas.

28. In a method which comprises introducing into the converging portion of a nozzle of the type used in hot water ejector systems comprising a converging portion and a diverging portion interconnected by a neck portion, a hot fluid under pressure and in liquid state, and partially evaporating andatomizing said fluid in said nozzle, the improvement which comprises providing a thin peripheral slit in the diverging portion of the nozzle and a hollow jacket surrounding said enclosure and creating in said hollow jacket a pressure less than that prevailing in the nozzle, whereby liquid present in said nozzle passes into said hollow jacket through said slit.

. UNITED STATES PATENT pFFIcE CERTIFICATE OF CORRECTION Patcn tNo. 3' Dated July 16,1974

Inventor) Otto Frenzl It is certified that error appears in the above-identified patentand that said Letters Patent are hereby corrected as shown below:

Column 1, line, 15, the word "paragraph" should be "S" Column 3, line 49, the word "pressure" should be "presence" Column 5, line 27, the word "adapted" should be "disposed" Column 7, line 21, the word "COne should be "Cone" I Column 9, line 20, the words "vertically exaporate" should be "partially evaporate" Signed a d sealed this 29th day of October 1974.

(SEAL) Attest:

MCCOY M. GIBSON JR. v C. MARSHALL DANN Attesting Officer '1 Commissioner of Patents F ORM PO-1050HO-69) USCOMM-DC ooawmus

Claims

1. In a nozzle of the type used in hot water ejector systems comprising a converging portion and a diverging portion interconnected by a neck portion and adapted to partially evaporate and atomize a hot fluid fed to the converging portion of said nozzle under pressure and in the liquid state, improved means for eliminating at least a portion of the predominantly liquid boundary layer ordinarily formed on the inner surfaces of said nozzle, comprising means formed in the wall of said nozzle which provide a conduit for the transmission of a fluid through said wall.

2. The nozzle of claim 1 wherein said means formed in said nozzle wall comprises orifices for injecting a gas from an external source into said nozzle through the wall of said nozzle.

3. The nozzle of claim 2 wherein said orifices are in the wall of the converging portion of the nozzle.

4. In a nozzle of the type used in hot water ejector systems comprising a converging portion and a diverging portion interconnected by a neck portion and adapted to partially evaporate and atomize a hot fluid fed to the converging portion of said nozzle unDer pressure and in the liquid state, improved means for eliminating at least a portion of the predominantly liquid boundary layer ordinarily formed on the inner surfaces of said nozzle, comprising means formed in the wall of the nozzle at a point other than the neck portion of the nozzle which provide a conduit for the transmission of a fluid through said wall.

5. In a nozzle of the type used in hot water ejector systems comprising a converging portion and a diverging portion interconnected by a neck portion and adapted to partially evaporate and atomize a hot fluid fed to the converging portion of said nozzle under pressure and in the liquid state, improved means for eliminating at least a portion of the predominantly liquid boundary layer ordinarily formed on the inner surfaces of said nozzle, comprising a gas permeable porous section in the wall of said nozzle through which a gas from a source external of the nozzle can be injected through the wall of said nozzle and into said nozzle.

6. The nozzle of claim 5 wherein said porous section is in the wall of the diverging portion of the nozzle.

7. In a nozzle of the type used in hot water ejector systems comprising a converging portion and a diverging portion interconnected by a neck portion and adapted to partially evaporate and atomize a hot fluid fed to the converging portion of said nozzle under pressure and in the liquid state, improved means for eliminating at least a portion of the predominantly liquid boundary layer ordinarily formed on the inner surfaces of said nozzle, comprising a thin peripheral slit in the nozzle wall for withdrawing at least a part of the liquid comprising the boundary layer from said nozzle through said slit.

11. In a nozzle of the type used in hot water ejector systems comprising a converging portion and a diverging portion interconnected by a neck portion and adapted to vertically exaporate and atomize a hot fluid under pressure and in the liquid state introduced into said converging portion, the improvement which comprises a porous section in said nozzle in contact with the interior of said nozzle, an enclosure surrounding said porous section and having a chamber therein communicating with said porous section, and means for supplying said fluid to said chamber, in its gaseous state, whereby said gaseous fluid permeates said porous section and creates on the inner surface of said porous section a layer of said gaseous fluid.

14. The nozzle of claim 13 wherein said means for creating an obstacle comprises a plurality of ribs extending radially into said intermediate section from the wall of said intermediate section, and wherein said means for injecting said fluid comprises a plurality of orifices in the wall of said intermediate section, said orifices communicating with manifold means from which said fluid, in its gaseous state, is supplied to said orifices, said orifices being disposed to inject said fluid into the wake created by said ribs.

15. In a nozzle of the type used in hot water ejector systems comprising a converging portion and a diverging portion interconnected by a neck portion and adapted to partially evaporate and atomize a hot fluid under pressure and in the liquid state introduced into said converging portion, the improvement which comprises means forming a slit in the diverging portion of said nozzle which provides communication between the interior and exterior of said diverging portion, a jacket enclosing at least a portion of said diverging portion and containing therein a hollow chamber, said chamber communicating with said slit, and means for creating in said chamber a pressure lower than that prevailing in said nozzle, whereby liquid on the inner surface of said nozzle is drawn out of said nozzle through said slit into said chamber.

16. The nozzle of claim 15 wherein said means forming said slit comprises two separate axially aligned and cooperating portions forming said diverging portion of said nozzle, and means for maintaining said axially aligned portions in spaced relationship to form said slit between the adjoining edges of said portions.

17. The nozzle of claim 15 wherein said slit is a thin peripheral slit.

18. In a nozzle of the type used in hot water ejector systems comprising a converging portion and a diverging portion interconnected by a neck portion and adapted to partially evaporate and atomize a hot fluid under pressure and in the liquid state introduced into said converging portion, the improvement comprising means for providing on the inner surface of the nozzle, from means other than the vaporization of the liquid feed to the nozzle caused by the diverging portion of the nozzle, and from a gas source external to the nozzle, a gaseous fluid in contact with the inner surface of the nozzle which is capable of making an energy contribution to the nozzle.

21. The method of claim 19 wherein said means comprises a porous section in the nozzle wall and wherein said fluid is a gas which is injected through said porous section into said nozzle from a gas source external to the nozzle.

24. The method of claim 19 wherein said boundary layer is eliminated by passing a gas, from a gas source external to the nozzle, through said fluid transmission means in said nozzle wall to form in said nozzle a gaseous layer and maintaining said gaseous layer in contact with the inner surface of said nozzle, said gaseous layer further characterized in that it creates an energy addition to the nozzle.

25. The method of claim 19 wherein said hot fluid is water.

28. In a method which comprises introducing into the converging portion of a nozzle of the type used in hot water ejector systems comprising a converging portion and a diverging portion interconnected by a neck portion, a hot fluid under pressure and in liquid state, and partially evaporating and atomizing said fluid in said nozzle, the improvement which comprises providing a thin peripheral slit in the diverging portion of the nozzle and a hollow jacket surrounding said enclosure and creating in said hollow jacket a pressure less than that prevailing in the nozzle, whereby liquid present in said nozzle passes into said hollow jacket through said slit.