US2352472A - Refrigeration - Google Patents

Description

June 27, 1944.

c. c.f cooNs REFRIGERATION Filed June 12, 1940 2 S heet s-Sheet 1 l I I I u I I INVENTOR- Y Carla's C. 'oons ATTORN EY June27, 1944. v c, O NS 2,352,472

' REFRIGERATION Filed June 12, 1940 '2 Sheets-Sheet 2 INVENTOR ATTORNEY Curtis C. Coons Patented June 27,1944

ENT' OFFICE REFRIGERATION Curtis '0. Coons, NorthCanton, 01110, assignor The Hoover Company, North Canton, Ohio Application June 12, 1940, Serial No. 340,038

- Claims. (01. oz-119.5)

This invention relates to the art of refrigeration and more particularly to a novel absorption refrigerating system having a solution circuit so constructed and arranged that the same produces improved results.

It has been shown by long experience that boiler for three-fluid absorption refrigerating systems of the domestic type should be constructed in the shape of. an elongated tube having a central heat passageway therethrough, This construction has been found to be the most advantageous in the type of system under consideration without causing deleterious or dangerous conditions due to incomplete combustion or condensation of moisture from the gases flowing through the central boiler tube The boilers of the above mentioned type, howwhen taken in connection with the accompanying I I drawings, in which:

ever, are thermally inefllcient due to the localized heating area therein and due further to the fact that the large draft tube which'is made necessary for safety reasons does not provide the most advantageoug heat transferarrangement between the hot gases and the fluids in the system.

Another disadvantage of the boiler construction previously used results directly from the fact that the liquid tends to stagnate in certain sections of the boiler without taking a useful part in the vaporizing process.

Accordingly, it is an object of the present in-' vention to provide an absorption refrigerating system embodying a solution circuit and vaporizing construction which will overcome the abovementioned disadvantages of the prior art.

More specifically, it is a'prlncipal object of the present invention to provide a three-fluid absorption refrigerating machine including a boiler in which a local circulating circuit is set upso ar-.

ranged that the same is subjected to the hottest gases which are available for heating the solu-' tion and which is also so constructed and arranged as to eil'ectlvely prevent stratification of inactive bodies of liquid in portions of the boiler.

It is a further object of the invention to pro-.

vide a boiler construction for a three-fluid absorption refrigerating system in which a strong local circulation is set up in which liquid is withdrawn from the boiler, conducted through an intensely hot zone and then is returned to another I portion of the boiler which tends to improve the heat transfer and which also enables the boiler to operate at more uniform temperatures throughout the extent thereof, thus improving it operating eiliciency.

Other objects and advantages of the invention will become apparent as the description proceeds Figure 1 is a diagrammatic representation of a refrigerating apparatus embodying the present invention.

Figure 2 is an elevational view in partial section of a boiler-analyzer construction incorporated in the apparatus of Figure 1.

Figure 3 is a diagrammatic representation "modified form of the invention, and

Figure 4 is an elevational view, partly in section, of aboiler construction utilized with the form of the invention illustrated in Figure 3.

Referring now to the drawings in'detail and first to Figure 1 thereof, there is illustrated a three-fluid absorption refrigerating apparatus comprising a boiler B,.an analyzer D, an aircooied rectifier R, a tubular air-cooled condenser C, an evaporatorE, a gas heat exchanger G, a tubular air-cooled absorber A, a solution reservoir S, and a circulating fan F which is driven by a suitable electrical motor M. These elements of a are suitably connected by various conduits, to be described hereinafter, to form a pluralityoi' gas and liquid circuits constituting a complete refrigerating system. a The above described refrigerating system will be charged with a suitable refrigerant, such as ammonia, a solvent therefor, such as water, and a pressure equalizing medium which is inert with respect to therefrigerant and solvent, preferably a dense inert gas likenitrogen.

The boiler will-preferably be heated by a fuel. burner H which is supplied with fuel by a mechanism under the control of a regulating valveV.

The application of heat to the boiler B liberates refrigerant vapor from the strong solution normally therein contained. The vapor so liberated passes upwardly through the analyzer D in counterflow relationship and in contact with strong solution returning to the boiler. The

vapors then pass from the upper portion of the analyzer D to the upper portion of the condenser C by way of the. conduit II which includes the rectifier R.

The absorber, gas heat exchanger and evapora tor together form a circuit for the inert" gas which includes a circulating fan F. The gases discharged from the circulating fan F are conveyed therefrom to the bottom part of the evaporator E by way of the conduit It, the gas heat exchanger G, and the evaporator gas supply conduit ll. After traversing the evaporator the inert gases are conveyed'from the upper portion thereof to the bottom portion of the absorber A by way of the conduit II, the gas heat exchanger G, and the conduit 18. After flowing upwardly through the absorber A the inert gases are returned to the circulating fanF by means of the conduit I], thus completing the inert gas circuit.

The refrigerant vapor which is supplied to the condenser C is liquefied therein and the liquid is conveyed from the bottom portion of the condenser to the bottom portion of the evaporator by way of the conduit. and a conduit it which includes a downwardly extending U-shaped portion and opens into the bottom portion of the evaporator gas supply conduit IS. The condenser sides of the conduits l4 and I! are vented by means of a conduit is to the rich gas side of the gas heat exchanger to provide'a vent for the condenser and. to subject the condenser, rectifier,

- boiler and analyzer to a pressure lower than that prevailing in the evaporator gas supply conduit l3. Consequently there is a pressure balancing liquid column formed in the condenser side of the conduit is to a height sufflcient to balance the pressure diii'erential existing between the conduits i3 and II.

Though the evaporator may be of any desired construction, it is preferred, in accordance with the present invention, to be of the type in which the inert gas circulates therethrough with a velocity suflicient to propel the liquid refrigerant through the evaporator as it is evaporating. A

speciflc example of an evaporator of this type is disclosed and claimed in the co-pending application of Curtis C. Coons and William 1-1; Kitto,

Serial-No. 388,395. flled April 2, 1941, which is, a

continuation-in-part of application Serial No. 220,189, flled July 20, 1938, now Patent No. 2,328,196, dated August 31, 1943. An anti-blocking drain II is connected between a solution conduit 2', to be described hereinafter, and the 'bottom of thelevaporator E. The connection between the conduit "and evaporator E is such that the evaporator is not drainedcompletelybut liquid cannot accumulate therein above a predetermined level.

The lean solution formed in the boiler B by the expulsion of refrigerant vapor therefrom is conveyed from the boiler to the reservoir 8 by way of the conduit 20, the liquid heat exchanger L, and a flnned looped precooling conduit II. The upper portion of the reservoir 8 is vented to the suction conduit ll of the circulating fan F by means of a conduit 22, whereby the liquid level in the reservoir 8 will be raised to the maxi! mum possible height due to the fact that the same is vented from the lowest pressure area in the system.

The solution supplied to the reservoir is conveyed therefrom to the suction conduit ll adjacent its point of connection with the upper end' of the absorber A by way of a gas lift pump conmedium and refrigerant vapor which is flowing walls of the absorber and the cooling fins attached thereto.

The strong solution formed. in the absorber. A drains to the bottom portion thereof from which point it is conveyed to the upper portion of the analyzer D by way of the conduit 28, the solution heat exchanger L, andthe conduit 21, thus completing the "absorption solution circuit externally of the boiler-analyzer system.

Fuel is supplied to the burner K through a supply conduit III which isunder the control of the solenoid valve V. A by-pass conduit 2! is provided around the valve V to maintain a small pilot or igniting flame on the heater H during periods when the valve V is in closed position.

A suitable thermostatic control mechanism Si is provided to be responsive to evaporator temperature and operates a swtch which is interposed between the electrical conductors I2 and 33 to break the circuit therein. The conductor 32' is connected to a source of supply as is the conductor 34. The conductor 33 is connected to a conductor 35 which connects between the motor M and the solenoid valve V. The conductor I4 connects directly to a conductor 38 connected between the valve V and motor M. Consequently closure of the switch mechanism to complete the circuit between the conductors 32 and 33 simultaneously energizes the motor to operate the circulatlng fan and energizes the valve V to open position to maintain a full flame on the burner H. Opening of the circuit between the conductors 32 and 33 de-energizes the motor and valve to render the fan and heater inoperative.

Referring now to Figure 2, it will be seen that the boiler B comprises an elongated tubular body portion 38 which is pierced by central combustion tube or flue 39 which, as seen in Figure 1, ispositioned to receive hot products of combustion end of the combustion tube 30 connects to a suitable products of combustion disposal flue 40.

The analyzer D comprises an upright tubular body 42 which opens at its lower end into the upper side of the boiler body ll adjacent the right hand end thereof asis shown in Figurefl. A plurality of staggered baflie plates are provided within the analyzer D to provide a tortuous path of flow for the ascending vapors and the descending solution which is supplied by he conduit 21.

In accordance with'the present invention a mechanism is provided for setting up a strong local 'circulation within the boiler body II. This mechanism comprises a conduit. which opens into the bottom central portion of the boiler body 30. The conduit 4!. extends to the right hand end of the boiler, as indicated in Figure2, where it has'a vertically extended section 46 which extends into the bottom portion of the combustion flue 39. The section 48 is Joined to an upwardly inclined elongated section 41. which extends to the left hand end, as viewed in Figure 2,

of the combustion tube is slightly beyond the upwardly therethrough' from the evaporator.

The so ution absorbs refrigerant vapor from the mixture and the resulting heat of absorption is rejected to cooling air flowing over the exterior conflnes of the boiler body 38. The -U-bend section as of the tube extends through the wall of .the extended portion of the combustion tube ll and opens into the top end portion of the boiler body 38. I

The conduit circulator 45 to 48 which includes the section 41' directly in the combustion tube I! provides a means for setting up a. strong local circulation within theboiler. Also the tube 41 are fairly 'well prevented due to the disturbance gases'discharged from the burner H into the tube 39 are quickly cooled at their outer sides and tend to maintain an inner core of extremely hot gases. The tube 41, however, is directly subjected to this inner core of hot gases and contains a vastly greater ratio of heat conducting metal to fluid body than is the case between the conducting tube 39 and the boiler 38, wherefore extremely hot conditions prevail within the tube 41.

This arrangement causes a local circulation due to the vapor bubbles evolved in the tube 41 which operates as a vapor lift pump to pull solution from the bottom portion of the b'oilerto conduct the same through a hot zone and to return the heated solution to the top portion of the boiler.

The arrangement of the boiler assembly eliminates stagnation. Stagnation at the left hand end of the boiler B is. fairly well prevented by reason of the connection thereto of the lean solution oiftake conduit 20. Likewise stagnant conditions at the extreme right hand end of the boiler therein of the vap'ors flowing into the bottom portion of the analyzer column and also because of the liquid flowing from the analyzer into the boiler. Another factor tending to eliminate undue stagnation at the right hand end of the boiler results from the fact that this is the portion of the boiler which directly and immediately receives the-hot flame from the burner H.

The central portion of the boiler, however, connects at its bottom into the tube It, thus pre-. venting stagnation at that point. Due to the very hot conditions prevailing in the tube 41 considerable solution is vaporized therein as well as refrigerant which is previously dissolved in the solution. It istherefore desirable that this 40 liquid and vapor be returned to the boiler at a point remote from its connection with the analyzer in order to prevent 'the solution vapor from entering the analyzer and at a point close to the ofl'take conduit 20 in order to permit the very lean solution discharged from the conduit 41 to flnd its way to the absorber without traversing all of the boiler. Both these objects are well met by having the conduit 48 open into the boiler at the end thereof remote from the analyzer and directly over its connection with the conduit 20.

v The solution vapor which is discharged from the conduit is as well as the vapors of the refrigerant travel to the right along through the liquid contained in the boiler body 88. In this-process the solution vapors, having a much higher-boiling point than the refrigerant vapors, are condensed in the boiler and serve further to heat the contents thereof and further serve to agitate the fluids therein contained which in turn im*- proves the transfer and evolution of refrigerant f vapor. V

The culminating effect of all these factors is to produce a boiler construction having a remarkably high efficiency and reliability.

Referring now to Figure 3, a different construction of apparatus is disclosed. In this form of the invention the heat applied to the boiler B by means of the burner H generates refrigerant vapor therein which operates through a vapor lift pump construction to lift the lean solution portion of the. condenser C by way of the con- 76 through the boiler in a, manner. to be described hereinafter. The lean solution ultimately is con veyed from the boiler to the upper portion of the absorber A by way of the conduit Bl, the liquid heat exchanger L', and the conduit 57.

The absorber in this form of the invention is shown as being of the plate type and will be provided with a suitable indirect air'cooling system, .not shown. The rich solution formed in the absorber is then returned therefrom to the analyzer D by way of the conduit 58, the liquid heat exchanger L and the conduit 59 The rich solution is then returned from the analyzer to the boiler by means of the conduit 80, thus completing the absorption solution circuit externally of the boiler 38'.

The evaporator E and the absorber A and the gas heat exchanger G are suitably connected to form an inert gas circuit. Lean gas formed in the absorber A is conveyed from the upper portion thereof to the bottom portion of the evaporator E' by way of the conduit 82, the gas heat exchanger G and the .evaporator gas supply conduit 63. The inert gas flows upwardly through the evaporator in counterflow relationgas is conveyed from the upper portion of .the

.evaporator E" to the bottom portion of the absorber A by way of the conduit 65,-the gas heat exchanger G and the conduit 66.

The evaporator is drained of non-condensible material by means of a conduit Bl whichppens into the rich gas side of the gas heat exchanger,

thus discharging the non-condensible material into the bottom portion of the absorber A" where duit 52, a bubble type analyzer D and theconship tothe liquid refrigerant which is eva.po-- rating into the inert gas. The resulting enriched side of the u shaped conduit I by means of itconduit I 0.

This form of th invention utilizes the .well known gravity type of gas circulation in which the inert gas is circulated by the density differential between the cold rich gas descending from will be arranged in a known manner'to respon to the temperature of the evaporator E.

Referring now to Figure 4, the construction oi'the boiler and its associated parts is illustrated and will be described in detail. The boiler B comprises a tubular elongated body portion" which is pierced-by a combustion tube 14 adapted to receive hot products of. combustion from the burner H. The annular space formed between the elements It and it is divided bottom portion of the enclosure II.

by means of an annular partition II into right and left hand boiler spaces II and I1, respectively. The vapor lift pump 50 opens \into the left hand end of the space 11, as viewed hrFigure 4, and the separation and return conduit Bl opens into the right hand end of the chamber l8.

,A local solution circuit within the boiler section prevent stagnation and to increase the emciency as it progresses to the right and finally opens into the extreme right hand end and upper portion of the chamber I8.

Likewise the chamber 11 is provided with a 1 local solution circulating mechanism which com- The conduit 8! opens into prises a conduit ii. the bottom central portion of the chamber Il, extends to the right, as viewed in Figure 4, executes a return bend and then extends the entire length of the combustion tube 14, rising as it progresses to the left, as viewed in Figure 4. The tube'll then has a return bend portion which opens into the upper extreme left hand end portion of the chamber ll. Y

As shown, the lean solution oi'ftake conduit 5 opens into the bottom of the right hand end of the chamber It and the strong solution return conduit ill opens .into the bottom of the right hand end of the. boiler chamber 11.

The operation of this form of the boiler construction is as follows: Strong solution entering through the conduit 60 is heated within the chamber 1] and vapor formed therein serves to elevate the solution through the vapor lift conduit 50 into the upper end' of the vessel Ii. A strong local circulation of solution through the boiler 11 is set up because of the tube II which is so arranged as to prevent stagnation of the solution in any part of the-chamberl'l. Also the high heat to which the conduit ll is subjected in the combustion tube 14 serves to generate further refrigerant vapor from the solution and this weak solution and refrigerant vapor then discharge into the chamber 11 adjacent the vapor .lift pump so that the vapor-may immediately traverse the pum and may also be available for elevating the lea I solution directlyv ther'ethrough into the vessel 5|. The pump 50 discharges into the vessel 5i and the vapor is taken off from the upper end thereof by means of the conduit 52. The solution supplied to the conduit 5| flows downwardly therethrough into the chamber ll and ultimately from the chamber I6 through the conduit 86 to the absorber. A strong local circulatlonis set up within the chamber It by reason of the conduit 80 which is also so arranged with respect to, the vessel as to prevent stratification or stagnation of any part of the liquid therein contained.

The arrangement of the conduit II is such that vapor formed therein is discharged into the chamber IO adjacent its point of connection with the vessel it so that these vapors may immediately ris through the vessel II and join the vapors supplied to the upper portion thereof through the vapor liftpump l0. Furthermore, the lean solution which is discharged from the conduit 80 mayimmediately drop around the combustion tube 14 and be taken off through the conduit 58. This last procedure is greatly facilitated by the fact that lean solution is denser than rich solution and tends naturally to fall to the Thus, in this form of the invention a plurality of circulating conduits are provided in order to of each section of the'boiler.

It is within thepurview of each form of the invention to provide the circulating tubes which extend through the boiler combustion tube with fins in order to increase the heat absorption area thereof. if desired. It is also within the purview of the invention to provide the form of the invention illustrated in Figure 1 with a plurality of circulating elements and to provide the form of the invention illustrated in Figure 4 with only one such element if desired, though it is believed that the arrangements shown constitutes the most eflicient forms of.domestic type refrigerating machine.

In each form of the. invention a means is provided which effectively prevents stratification and stagnation of the solution in portions of'the apparatus and which also simultaneously induces a circulation of liquid within the boiler itself and also in so doing removes liquid from the boiler,

conducts it through an intensely hot zone where it is brought into contact with hot gases which normally are not efiicaciously utilized to heat the boiler and then returns the resulting v ry lean solution and vapors to the boiler at a point or points at which the solution and ,vapor can be utilized most eillcaciously. The terms generator" and boiler are used interchangeably herein to designate a vessel or conduit subject to heating for the purpose of evolving vapor from a contained liquid.

Not only does the present arrangement improve the efllciency of'vapor expulsion but it improves the entire refrigerating process by insuring that all the liquid therein contained continuously takes a part in the process and it also provides the absorber/with leaner solution whereby the absorber is able to perform its function more efficiently.

While I have illustrated and described my invention in considerable detail, it is to be understood that the invention is not to be limited thereto but that changes and variations may be made without departing from the spirit thereof or thescope of the appended claims.

I claim:

1'. In an absorption refrigerating system inyolving an evaporator and an absorber connected for circulation of an inert gas therebetween, a generator, means for liquefying refrigerant vapor produced in said generator and for supplying the liquid refrigerant to said evaporator. means connecting said absorber and generator for circulating an absorption solution therebetween, sa'id generator comprising an elongated tubular body having a heating flue extending lengthwise therethrough, acombustible fuel burner positioned to discharge products of combustion through said flue, an analyzer extend ing above and opening into the top portion of generator body remote from saidanalyzer, and

a circulation conduit including a portion extendhis lengthwise of and in said flue connecting the bottom central portion. of said generator body to the top end portion thereof remote from said analyser.

assaua 2. Absorption refrigerating apparatus comchamber to an elevation from which said'solutionmay flow by gravity to said absorber, means for conveying solution elevated by said vapor lift 7 means to a second one ofsaid heating chambers,

means for conveying solution from said second heating chamber, and means for circulating solution from at least one of said heating chambers through a high temperature heating chamber and'back to the heating chamber from which it was taken.

3. Absorption refrigerating apparatus comprising an evaporator, an absorber, means con necting said evaporator and said absorber for flow of inert gas thereb'etween, refrigerant vapor liquefying means arranged to discharge refrigerant liquid to said evaporator, a generator including an elongated body, a fine for products ofcombustion piercing said body to form an annular heating chamber, means dividing said chamber into first and second heating sections,

a combustible fuel burner for discharging prod-- ucts of combustion into said flue, vapor lift means necting said evaporator and said absorber for flow of inert gas therebetween, refrigerant vapor liquefying means arranged to discharge refrigerant liquid to said evaporator, a generator including an elongated body, a flue for products of combustion piercing said body to form an annular heating chamber, means dividing said chamber into first and second heating sections, a combustible fuel burner'for discharging products of combustion into said flue, vapor lift means opening into the upper portion of said first section adjacent one end thereof, means opening into the upper portion of one end of-said second section forsupplying thereto solution discharged by said vapor lift means, means for conveying rich solution from said absorber to the bottom end portion of said first section remote from said vapor lift means, means for conveying lean "solution to said absorber from the bottom of the end portion of said second section to which solution is supplied, conduit means having a portion extending lengthwise through said flue for conveying solution from the bottom portion of said firstsection to a portion thereof adjacent said for conveying solution from the bottom portion of said second section to a portion thereof ad- Jacent the point at which solution is supplied to said second section.

5. Vapor generating apparatus for use with an absorption refrigeration apparatus comprising an elongated generator body, a heating flue piercing said body lengthwise thereof, means into' said absorber, means for conveying absorption solution from said absorber to said first heating section, means for conveying refrigerant 1 vapors produced in said generator to said liquefying means, and means for circulating solution from each of said heating sections-in heat exchange relationshipwith products of combustion fiowing'through said flue and back to the section of origin.

separating said body into first and second heating chambers, means for supplying strong solution-to said first chamber, means for conveying solution from saidflrst chamber to said second chamber, means for removing weak solution from said second chamber, means for removing vapor produced in said chambers, and a conduit connected between spaced parts of one of said heating chambers and extending through said flue.

, CUR TIS C. COONS.

4. Absorption refrigerating apparatus comprising an evaporator, an absorber, means con-

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