US1816975A - Refrigeration apparatus - Google Patents

Description

Aug. 4, 1931. D. F, KEITH l REFRIGERATION APPARATUS 4 Sheets-Sheet 2 Filed Dec. 27, 1927 i l l ,Ml

I N VEN TOR.

A TTORNE Y.

ug. 4, 1931. D. F. KEITH REFRIGERATION APPARATUS 4 Sheets-Sheet 3 Filed Dec.

gf w31- D. F, KEQTH REFRIGERATION APPARATUS Filed Deo. 27, 192'? 4 Sheets-Sheet 4 Patented Auig. 4, 1931 UNITED STATES PATENT OFFICE DAVID F. KEITH, OF CLEVELAND, OHIO, ASSIGNOR T IPERFECTION STOVE COMPANY, 0F CLEVELAND, OHIO, A CORPORATION OF OHIO REFRIGERATION APPARATUS Application filed December 27, 1927. Serial No. 242,574.

This invention relates to improvements in refrigeration apparatus of the intermittent absorption type.

Apparatus of this type consists, generally,

of a closedv system incorporating a generator-absorber; an4 evaporator-receiver; -a delivery conduit leading from the generator absorber-to the evaporator-receiver, said conduit usually involving a. condenser and, pref- 1o erably a dehydrator 1n advance of the condenser; a return conduit leading from the evaporator above the maximum liquid level therein to the generator-absorber below the minimum liquid level'therein, together with means for intermittently heating the generator-absorber.

The system permanently contains a quantity of a suitable refrigerant and an absorbent for the refrigerant. Forthe purpose of the 80 present disclosure this may be considered as the usual solution of water as the absorber and ammonia as the refrigerant, in proper proportions, but without any intention of limiting the'fp-resent invention to the use of these specific ingredients. Where the terms are used in the specification and claims they are to be understood as embracing any and all equivalents known to the art.

At the beginning of a cycle of operation substantially the whole amount of solutionl is present in the generator-absorber. By heating the generator-absorber for a given period of time, the ammonia is driven out of solution and passes therefrom in the form of vapor into the delivery conduit on its way to the evaporator-receiver, vbeing dehydrated and condensed in the respective appropriate- 1y designated parts of said conduit, arriving in the evaporator-receiver in the form of 40 liquid anhydrous ammonia. This phase of the operation is what is known as the heating period, and during this period a relatively high pressure prevails throughout the system which. contributes to the condensation of the ammonia in the cooler parts of the system, as in the condenser, from which the lique- "lied refrigerant Hows to the evaporator-receiver where it is stored awaiting the evaporation period. As used hereinafter, the term evaporator, 1n certain mstances, may or vapparatus is greatly impaired, or virtually may not embrace the receiver the intent will be clear from the context.

As soon as the heat is removed from the generator-absorber, what is known as the cooling period begins, and during this period, a reversal of the foregoing conditions is effected. The weakliquor in the generatorabsorber, by reason of its affinity for the ammonia, starts to absorb the ammonia gas that is drawn through the return conduit from the evaporator, and as a consequence of this the pressure in the system falls. Incident to this fallsin pressure, the liquid ammonia begins to boil, being vaporized b-y the heat abstracted from the relatively warm air surrounding the evaporator, thus cooling said air for refrigeration purposes. In this prior practice suitable means, such as valves, traps, etc. is employed for preventing the' ammonia gas from returning to the generator-absorber by way-of the delivery conduit and condenser and said gas is thus compelled to pass through the return conduit. Alll this will be recbgnized by those acquainted with the sub-v ject as being common to apparatus of the type in question.

In refrigeration apparatus of the class described, unless some means is employed for overcoming the difficulty, the eiiciency of the 80 destroyed, by an accumulation in the evaporator ofa quantity of the aqueous contents of the system, the quantity gradually increasing with each cycle of operation until the effectiveness of the apparatus becomes practically nil. y/

' It is the primary purpose of my invention to provide refrigeration apparatus of the type in question incorporating thoroughly reliable meansthat is positive of action and immune from disorder for automatically returning to the generator-absorber during each heating period, all residue liquid that may have been left in the evaporator end of the system at the conclusion of the previous cooling period. To the attainment of this end I employa liquid return means or Siphon that acts during the early stages of the heating period, as will hereinafter more fully appear.

A further and very important object of the invention is to provide, in apparatus of the class described, a unique, simple and highly etlicient means, devoid of valves and moving parts, Jfor causing the ammonia vapor to return from the evaporator to the generatorabsorber without any substantial part of it passing through the condenser, and for assisting in the rapid absorption of the ammonia vapor in the water; and, more specifically, to provide a liquid seal for accomplishing this result that involves the liquid anhydrous ammonia that is in the evaporator.

Heretofore attempts have been made to use the highly volatile liquid anhydrous ammonia as a seal to prevent the return of the ammonia vapors through the condenser, but these attempts have tailed because the tubes or conduits which it was desired to seal had invariably been exposed in the region of the seal to the relatively high temperature of I surrounding air, thereby causing the ammonia to boil and thus, to a very considerable eXtlent at least, defeating the object of the sea ln my improved form of apparatus l am enabled to use liquid anhydrous ammonia as a seal because the tube which it is desired to seal, or a material p'art of it from its sealed end, 'is located inside the evaporator and the evaporation ot the surrounding ammonia tends to keep it cool. To minimize the height of the liquid level in said tube necessary to effect said liquid seal, l use a very shallow submergenee of the return conduit in the liquid in ythe generator-absorber, it being evident that these analogous conditions existing at the opposite ends of the system balance each other. By reason 'of this arrangement l am enabled to accomplish Athis result without having to resort to traps and valves.

Other and more general objects of the invention are vto provide a highly efficient refrigeration apparatus of the above mentloned type thatis simple of construction and involves no mechanically operating parts or valves; that is relatively inexpensive; that requires a minimum of attention; that is at all times in readiness tornse Vand does not have to be manipulatedin any way, as for the .purpose of collecting its contents in a given part of the system, as in the generatorabsorber (should the normal conditions of the apparatus have been disturbed through handling or shipping), preparatory to firing, the apparatus automatically reconditioning itself upon the initiation of each cycle ot operation; to provide apparatus of the type referred to that is so constructed and arranged as to operate in cycles of given duration-as, for example, 24 hour periods, and which is tired by oil burningl apparatus involving a reservoir or font of a capacity to accommodate just enough fuel to generate the heat required to initiate one cycle of operation.

a cycle ot operation.

Various embodiments of the invention by which the foregoing object-s, with others hereinafter appearing, are attained, are illustrated more or less diagrammatically in the accompanying drawings, wherein Fig. l represents a sectional elevation of a refrigeration apparatus constructed in accordance with one form of the invention; Figs. 2, 3 and 4 are similar fragmentary views showing modifications, while Fig. 5 is a graph or chart on which is plotted curves representing the pressure and temperatures preyailingduring Referring by like numerals to the parts common to the various illustrative embodiments ofthe invention herein disclosed, 1 designates a generator-absorber, 2 an evaporator which serves also as a receiver for the refrigerant condensate, 3 a. delivery conduit that leads from the generator-absorber toA the evaporator, and l a return conduit by which the ammonia gas is conducted from the evaporator to the generator-absorber. Respective parts of the delivery conduit 3 constitute a dehydrator 5 and a condenser 3, the former being shown as a portion of said conduit that is inclined downwardly toward the generator-absorber, and the latter as a coiled portion ot said conduit. Both the dehydrator and condenser are located within a box or casing 7. shown as equipped with a lling cap 8. and adapted to permanently contain, preiferably to its full capacity, a cooling agent, such as water.

ln each of the embodiments, the delivery conduit leads downwardly through the top ot the evaporator to a point near the bottom thereof so that as long as practically any liquid isvpresent in the evaporator it will seal said conduit against the escape of ammonia gas from the evaporator therethrough. The advantage ot this arrangement will be pointed out presently. ln every case the bottom' of the evaporator is desirably formed to provide a sump or basin into which the discharge end of the delivery conduit dips. and wherein the residue liquid in the evaporator collects b v gravity. While the curved bottom wall of a spherical or horizontally disposed cylindrical vessel, or any equivalent thereof, E would. to a large measure serve the purpose` l show. in Figsfl, 2 and 4, a sump designated 2aM in the form cfa distinct depression in the bottom wall of the evaporator. For claim purposes this sump or basin will, in some instances be referred to as a receiver.

The generator absorber is preferably equipped with heat abstracting veins l0, similar in style and purpose to the tins on the cylinder of an air-cooled motor, and this vessel is shown as located in a vertical tine, indicated by dot-and-dash lines and designated 1l.` The evaporator is placed in therefrigeration compartment, also indicated by dotand-dash lines and designated l2.

In the broader aspect of the invention the generator-absorber unit of the apparatus may, in accordance with prior practice, com-- prise separate chambers or vessels wherein the respective processes of generation and absorption are carried on and likewise the evaporator-receiver may consist of different compartments'or containers in the former of which the refrigerant` condensate is collected and from the latter of which it evaporates. Where used herein, the terms generator-absorber, generator-absorber section, generator-absorber end of the system, evaporator, evaporator-receiver", evaporator section and evaporator end of the system, are to be understood asembracing all modifcations of the respective elements.

Situated below the generator-absorber is an oil burner 15, preferably of the so-called wickless type, that receives its supply of fuel through a pipe 16 from a cup 17 within which is adapted to be placed in inverted position a .font or reservoir 18 which, in the present case,

is in the form of a bottle. This fontlor reservoir is of sufficient capacity to accommodate just enough oil to lsupply heat for initiating one cycle of operation of the apparatus and, for convenience, the user may be supplied witha number of such reservoirs so that to replenish the fuel supply for each operation means simply the removal of an empty font or] reservoir and the substitution therefor of a full one.

Associated with each embodiment of the invention is a Vliquid return means or siphon thatis designated generally by the reference Anumeral 20, the same being altered inl proportions to suit the various structures. It i's this siphon that constitutes the means for returning to the generator-absorber any residue liquid left in the evaporator end of the system after each cooling period. The action of the liquid return means or siphon will be fully explained hereinafter.

' illustrated in Fig. 1, the evaporator 2 is surmounted by a gas dome 25, downwardly through the top wall of which extends the adjacent en-l of the dischargeconduit 3, said end terminating within the sump 2a at the bottom of the evaporator. The short leg of the siphonQO is also extended through the upper portion of the gas dome 25 and has its receiving end disposed within the sump 2a, while the long leg of the siphon is shown as entering the delivery conduit 3 in subst-antially the horizontal plane of the upper portion of the gas dome and as descending through said conduit andzdepending a suitable distance into the generator-absorber. [t is to be understood, however; that, so far Y as the operation of the device is concerned,

rectly to the generator-absorber. The return conduit 4 connects at one end with the upper portion of the gas dome 25 and its opposite end is extended downwardly through the top Wall ofthe generator-absorber and terminates within this vessel below the minimum liquid level therein which level is indicated by the dotted line a. A sleeve 27, which may be common to all forms of the invention, surrounds the discharge end of the return conduit and is suitably supported Within the generator-absorber with its lower endspaced from the bottom wall of said vessel. The purpose of this sleeve will be explained when describing the operation of the apparatus.

The system is hermetically sealed and contains a quantity ofaqua ammonia or other equivalent refrigerant liquor, and when all the liquor is present in the generator-absorber 1 it stands at about the level indicated by the dotted line b. To start the apparatus in operation a reservoir or font 18, filled with oil, is inverted within the cup 17 and the burner 15 is lighted. According to thc graph of Fig. 5, whereon is indicated by means of appropriately designated curves, the temperatures and pressure prevailing during a cycle of operation, this act of lighting the burner and thus initiating theJ cycle is shown as having been performed at 9 oclock in the morning. By the heat from the burner iame, the temperature of the generator-absorber is raised during the first hour to substantially 325 F., according to the present example. This hour represents the heating period, or the interval of active heat, the fuel supply being such, as hereinbefore stated, as will be exhausted in practically that length of time. During this hour, as indicated by the chart, the pressure within the system rises to substantially 160 pounds, the most abrupt rise occurring within the very early stages of the heating period. On the cessation of heat-that is, after the fuel supply has been exhausted-the temperature of the generator-absorber andthe pressure i'n the system immediately start to drop, as will appear Lfrom an inspection of the graph. -fDuring the heating period, the ammonia in the generator-absorber is driven out of solution and in the form of vapor rises through the delivery conduit 3 and while passing through the portion of said conduit that constitutes the dehydrator designated by the reference numeral 5 all or the greater percentage of the wat-er vapors wherewith the ammonia gas is saturated condenses and flows back into the generator-absorber, the ammonia gas continuing on through the portion of the conduit'that constitutes the condenser 6 and condenses therein, the resultant liquid anhydrous ammonia being discharged into the evaporator 2.

At the conclusion of this phase of the operation the evaporator contains its maximum amount of liquid, the level of which is indicated by the dotted line c, and this body of liquid may contain a relatively small amount of aqueous condensate, it being practically impossible to obtain a complete dehydration of the ammonia vapors.

The cooling period starts with the cessation of heat, or, according to the graph, at the beginning of the second hour, and it continues on until the next `heating period which is represented by the graph as twenty-three hours distant. As previously stated, very soon after the heatis removed from the generator-absorber, the pressure within the system starts to drop abruptly. Under these the liquid level falls below the end of the conduit 3. This seal which, as will be gathered from the foregoing, prevents the escape of gas from the evaporator through the delivery conduit by way ofthe condenser and dehydrator to the generator-absorber is rendered especially eifective by the fact that a considerable portion of the delivery conduit adjacent its discharge end is housed within the evaporator and thus not only protected from the iniiuence of the relatively warm air within the refrigeration compartment but is maintained cool by the evaporation of the ammonia immediately surrounding it within the evaporator. It will be readily understood that if this portion of the delivery conduit were exposed tothe warmer surrounding air, the liquid anhydrous ammonia which it contains would immediately lash into gas and would set up a iow through the delivery conduit contrary to that desired.

As the ammoniagas escapes from the discharge end of the return conduit it is instantly absorbed by the solution in the generator-absorber. rlhis enriches the solution in the immediate vicinity of said end and this enriched or relatively strong liquor, having less specific gravity than the weaker liquor due to its ammonia content, tends to rise within the sleeve 27, thus creating an upward How of liquid through said sleeve, and this circulation continues as long as ammonia gas is being supplied from the evaporator, thereby insuring a very thorough mixing of the constituents of the aqueous refrigerant.

By the use of the sleeve 27 a very shallow submergence of the return conduit in the liquid in the generator-absorber is permitted the Siphon.

conduit and in the evaporator, which has a definite proportion to said head, is considerably less than it would otherwise have to be,

`and this, in turn, creates within the discharge end of the delivery conduit a correspond- -ingly low level of. the liquid /anhydrous ammonia. The advantage of this is that said liquid ammonia, standing so low in the portion of the delivery conduit that is housed in the evaporator, is effectively protected from the relatively warm air surrounding the evaporator and'is not to any degree gasiied and thus inflated so as to cause it to bubble up into the exposed portion of' the conduit but said ammonia is maintained in a heavy, dense liquid condition which greatly enhances the seal.

During the evaporation of the liquid anhydrous ammonia and the consequential absorption of heat thereby from the surrounding air in the refrigeration compartment 12, the temperature of said compartment is accordingly lowered'and, as indicated by the appropriately designated line on the graph of Fig. 5, this temperature is maintained within a range of less than 10 duringv the entire cycle of operation, it being the highest at'the conclusion of the heating period and the lowest about midway between suc-V cessive heating periods. y

riod, when the pressure within the system risesthe fastest, a part of any liquid that is present within the evaporator 2 is forced up the short leg of the siphon 20, and a part of the solution in the generator-absorber which at this time has a\level of about that indicated by the dotted line is likewise forced up the long leg, the quantities of liquid within the two legs approaching each other or meeting within the horizontal branch of Any refrigerant gas present within said branch will be absorbed by the liquid and, by reason of such absorption, will attract the separated ,columns of liquid tending to create a continuous liquid body from one end of the siphon to the other. As soon as this condition prevails a siphonic action is set up in the direction of the generatorabsorber whichdraws all residue liquid then j in the evaporator over into the generator absorber, the action being interrupted by the im u next heating period, and thenv only in case there is residue liquid inthe evaporator.

It may be explained at this point that before the inauguration of the heating period the pressure throughout the system, including that within the siphon 20, is practically uniform. As soon, however, as heat is applied to the generator' absorber, the gas pressure within that vessel rises rapidly, as previously set forth, and the same is, almost instantly communicated, with inconsequential variations, to all other parts of the system, including the interior of the sipho-n 20 through the intervention of the liquid that is present in and about the legs of the siphon. `Thateis to say: as the pressure rises it tends to equalize throughout the system andas a result thereof it forces the aqua ammonia that is in andabout the ends of the siphon tube up into the-legs of the siphon and the gas "that is trapped between the separated bodies of liquid is compressed to a pressure value substantially equal to that prevailing in the remainder of the apparatus. This gas, in its compressed state, and which is ammonia vapor, is readily absorbed by the aqua ammonia in the ends of the siphon and by reason thereof tends to drawthe separated bodies of liquid together.

Under this and other influences hereinbefore pointed out the liquid assumes or approaches a state of continuity throughout the length of the siphon with the result that the siphonic action is instituted.

The reasons forthe failure of the siph-onic action to reoccur at different stages in the operation of the apparatus may be explained as follows Since more than o f the maxi, mum pressure value is attained during about the first 20% (or the first twelve! minutes) of the (one-hour) heating period, there will be only a comparatively slight additional rise in pressure while the'temperature continues to climb to its maximum in the remaining (or 48 minutes) of the heatingperiod.v

Within the time of the rapid rise in pressure, there willbe practically no ammonia condensate collect in the evaporator because, at the temperatures prevailing, the pressure in the system is yet insufficiently high to promote condensation, the Hcondensation occurring in the interval of slowly rising pressure i and, because the additional rise in pressure lis slight, the liquid will not be elevated within the legs of the siphon suiiiciently to etablish a substantially uninterrupted body of liquid throughout the length of the siphon. It may also be pointed out in this connection that at the time of initial heating the pressure of the ammonia gas that is trapped withf in the siphonby the liquid seals at both ends thereof is low as compared to the rapidly risingpressure in the remaining portions of the system, while at the time we are now considering the pressure within the siphon is substantially the same as that prevailing through the system. Furthermore, after that time during which the pressure was rising the most rapidly, practically only unadulterated anhydrous ammonia collects in the evaporator, and this will not siphon for the reason that it flashes into gas as soon as it reaches the relatively warm zone where the siphon tube leaves the evaporator. Again, (with respect to the particular embodiments herein illustrated) at a point relatively early in the heating period, and after the siphonic action has taken place, the liquid in the generator-absorber will have boiled away to such an extent as to lower the liquid level in said vessel below the long leg of the siphon, andthis condition will positively prevent the setting up of any siphonic action. Thus it will be seen that there is no danger of depriving Ithe evaporator of any of its liquid anhydrous ammonia during the cooling period.

It may be desirable and advantageous, in some installations or embodiments of the invention, due to the' cabinet design or the size and shape of the space wherein the a paratus is to be accommodated, to locate t e generator-absorber at a higher elevation with respect to the evaporator than it occupies in the arrangement illustrated in Fig. 1. In such a case the inlet end of the siphon must be raised aoproximately a like distance to the elevation of the generator-absorber as otherwise the two ends of the siphon might be so disposed in relation to each other as to nullify or reverse the siphonic action. Means compensating for such a rearrangement of parts are `incor ,1 porated in the modifications of the inven- Y tion illustrated in Figs. 2 and 3. y

In Fig. 2 a closed casing 30 replaces the gas dome 25 of the previously described embodiment, and a transfer tube` 31 rises from the sump 2a through the top of the evaporator 2 into the casing 30 and terminates near the top thereof. The siphon 20 is arranged the same in this as in the former embodiment, its shorter leg passing through the upper end of the casing 30 and terminating adjacent the bottom thereof.

The operation of the present embodiment is substantially the same as that above described. Durng the early stages of the heating period, when the pressure is rising rapidly within the system, any liquid thatI` is left in'the evaporator after the cooling period will be forced up the transfer tube 3l into the casing 30 and from said casing, due to the rising pressure therein, up the short leg of the siphon, a corresponding action occurring in the long leg of the siphon, the action continuing in the manner already described until liquid fills the siphon when the siphonic action begins and draws over into the generator-absorber practically all liquid elevated into the casing 30 through the transfer tube 31. The remainder of the cycle of operation is the same as described above in connection with the first form of the invention.

Fig. 3 illustrates a construction wherein the generator-absorber 1 occupies substantially the4 same relation to the evaporator 2, as in the above described mod-ification, and

this relation of the two vessels is permittedv by reason of the fact that a third vessel 35, which serves the same purpose as the casing 30 of the modification shown in Fig. 2, is located a` distance above the evaporator. The operation here is the same as that immediately above described. In this case, as with its predecessors, the discharge end of the delivery conduit dips into the liquid anhydrous refrigerant in the evaporator, and a liquid seal is thus effected which prevents the return of the ammonia gas through the delivery conduit.

rlhe modification of the invention illustrated in F ig. 4 differs from the forms p reviously described principally in the provision of a permanent liquid seal for the end of the siphon 20 that is located in the generator-absorber end of the system. This liquid seal is provided by a cup 38 that is suitably supported within an enlarged. p0rtion 39 of the delivery conduit 3 where the latter joins the generator-absorber 1.

After the apparatus is once set in operation, liquid is always present in the cup 38 to avheight above the adjacent end of the siphon, and the quantity of liquid in the cup i's augmented during each heating period by condensate returning from the dehydrator 5. As in the former cases, the siphonic action occurs in the early stages of the heating period when the pressure is rising rapidly within the system with the result that the liquid surrounding the opposite ends of the siphon is forced up the legs thereof and is attracted by the trapped gas in the horizontal branch of the siphon which is readily absorbed by the liquid, thus establishing a continuous body of liquid throughout the length of the siphon which gravitates through the long leg into the cup 38 and overflows into the generator-absorber. When once the siphonic action is broken the relatively high pressure in the system is com- Kmunicated to the siphon and is maintained therein upon an accumulation of liquid anhydrous ammonia within the evaporator even after the pressure in the remainder of .the system starts to decline. Thus it will be seen that by this arrangement wherein both ends of the siphon are liquid sealed during the cooling period, there is a positive `safe-guard against the setting up of any siphonic action during this phase of the cycle of operation.

Reference has been made to the flue 11 i within which the generator absorber is situatedy The purpose of this flue is two-fold.

While the burner 15 is in operation, it serves to concentrate thc heat from the burner on the generator-absorber, and during the cooling period it serves to create a draft of cool air upwardly about the generator-absorber and more rapidly lower the temperature of this vessel so as to promote absorption of the ammonia gas by the weak liquor in the generator-absorber. Some ofthe heat that is stored within the cooling medium or water in the box or casing 7 is radiated into the upper portion of the fiue 11, and this heat rises and contributes to the maintenance of an upward draft of cool air through the lower portion of the flue. It may also be explained that this same action draws cool air between the bottom of the boX or casing 7 and the top of the refrigeration compartment, which, with the cool air rising through the flue 11, tend to reduce the temperature of the contents of said box or casing.

It is evident from the foregoing description that at the beginning of each operation, any liquid that is present in the evaporator is automatically drawn over into the generator-absorber. In other words, upon the initiation of eachf.operation, the system is reconditioned for the refrigeration phase of the cycle. On account of this, no preliminaries are necessary to place the apparatus in condition for its first firing after the machine has been assembled, filled and delivered to the user. This relieves the manufacturer of any care in the charging of the system as to the segregation of the liquid therein, and the user of having to give any attention to the draining of the contents into the generator-absorber preparatory to starting the apparatus in operation.

Having thus described my invention, what I claim is: y

1. ln refrigeration apparatus of the inte-rmittentabsorption type consisting of a closed system involving a generator-absorber section, and evaporator section and vapor conveying means through which said sections communicate; and a siphon independent of said means having its short leg opening into the evaporator section and its long leg opening into the generator-absorber section, the

Siphon being otherwise closed throughout its length to the interior of the system.

2. In refrigeration apparatus of theintermittent absorption type consisting of a closed system, in combination with the generatorabsorber unit and the evaporator unit, fluid conveying means through which said units communicate, a Siphon independent of said means and having its short leg opening into the evaporator unit and its long leg opening into the generator-absorber unit, the siphon being otherwise closed throughout its length lli@ to the interior of the system, and a receiver in which one terminal of the Siphon is disposed.

3. Refrigeration apparatus of the intermittent absorption type consisting of a closed system and involving a generatorabsorber and an evaporator, a gas dome rising from the evaporator, a delivery conduit leading from the generator-absorber through the top of said dome and downwardly through the evaporator and terminating adjacent the bottom thereof whereby liquid in the evaporator forms a seal for. the discharge end of said conduit, a return conduit leading from said gas dome to the 'generator-absorber and terminating in the latter vessel below the minimum liquid level therein, and a siphon having its short leg extended ddwnwardly through the upper portion of the gas dome and terminating adjacent the bottom of the evaporator and having its long leg eX- tending downwardly through the end of the delivery conduit adjacent the generatorabsorber, the latter end of said siphon being adapted to be liquid sealed in the generatorabsorber end of the system.

4. In refrigeration apparatus of the intermittent absorption type consisting of a closed y system, in combination with the generatorabsorber lsection and the evaporator section of said system, a dehydrator for the vapors that pass from the generator absorber section, a receptacle disposed within the generator-absorber section and into which said dehydrator discharges, and a Siphon having its short leg terminating in the evaporator section and its long leg terminating in said receptacle.

5. A refrigerator ofthe intermittent absorption type consisting of a closed system comprising a generator-absorber, an evaporator, a delivery conduit leading from the generator-absorber to the evaporator and 1nvolving a condenser, a return conduit leading from the evaporator to the generatorabsorber, the system enclosing a refrigerant and an absorbent for the refrigerant, means for intermittently heating the generatorabsorber, means for cooling the generatorabsorber during theintervals between heating periods, and a siphorrhaving its short leg terminating in the evaporator and its long leg terminating in the generator-absoiber.

6. A refrigerator of the intermittent absorption type consisting of a closed system comprising a generator-absorber, an evaporator, a delivery conduit leading from the generator-absorber to the evaporator and involving a condenser, a return conduit leading from the evaporator to the generatorabsorber, the system enclosing a refrigerant and an absorbent for the refrigerant, means for intermittently heating the generatorabsorber,'r`neans for cooling. the generatorabsorber during the intervals between heating periods, and a siphon having lits short leg terminating near the bottom of the evaporator and its long leg terminating in the genera- 'heating periods, a receiver in which the residue liquid left in the evaporator is collected at the conclusion of the cooling period, and a siphon for transferring liquid from said receiver to the generator-absorber, the siphon being initially filled due to changes in pressure in the system.

8. A refrigerator of the'intermittent absorption type consisting of a closed ,system comprising a generator-absorber, an evaporator, a delivery conduit leading from the generator-absorber to the evaporator and involving a condenser, a return conduit leading from the evaporator to the generator-absorber, the systemenclosing a refrigerant and an absorbent for the refrigerant, means for intermittently heating the generator-absorber, means for cooling the generator-absorber during the intervals between heating periods, the bottom of the eva orator being formed to provide a sump, an a siphon having its short leg terminating in the sump and its long leg terminating in the generator-absorber.

9. The combination 'with refrigeration apparatus of the intermittent absorption type involving a generator-absorber and an evaporator-receiver, the latter being located at an elevation above the maximum. liquid level in the generator-absorber, and communicative means through which a complete operative refrigeration cycle is effected; of a liquid return conduit independent of the beforementioned communicative means connecting the evaporator-receiver with the generator-absorber, a portion of which conduit is at an elevation above the maximum liquid level in the evaporator-receiver.

l0. The combination with refrigeration apparatus of the intermittent absorption type involving a generator-absorber and an evaporator-receiver, the latter being located at an elevation above the maximum liquid level in the generator-absorber, and communicative means through which a complete operative refrigeration cycle is effected; of a valveless liquid return conduit independent of the beforementioned communicative means connecting the evaporator-receiver with the generator-absorber.

i 11. The combination with refrigeration apparatus of the intermittent absorption type Oli involving a generator-absorber with means for heating and cooling the same and an evaporator-receive@ the latter being located at an elevation above the maximum liquid level in the generator-absorber, and commucative means through which a complete operative refrigeration cycle is effected; of a conduit independent ofthe beforementioned communicative y'meansothat opens into the evaporaton-receiver and thef -generator-absorber and isotherwise closed to the remainder of the system and has a part above the maximum liquid level in the evaporator-receiver, said conduit being liquid sealed in the generator-absorber at the beginning of the heating periods.

12. rlrhe combination with refrigeration apparatus of the intermittent absorption type wherein a refrigerant fluid and an absorbent fluid are used, and involving a generator-absorber section, with means for alternately heating and cooling the same, and an evaporator section, and communicative mea-ns for conveying refrigerantl fluid between the sectionsand which means is'necessary to a complete operative'refrigeration cycle; of a conduit independent of said communicative means for transferring absorbent fluid remaining'in the evaporator section at the end of each cooling period to the generator-ab- -sorber section at the beginning of the following heating period, said' conduit having its receiving end opening into the residue liquid collecting portion of the evaporator section and its discharging end liquid sealed in the generator-absorber section at the beginning of the'heating periods, the intermediate portion of said conduit being at an elevation above the maximum liquid level in the evaporator section.

13. The combination with refrigeration apparatus of the intermittent absorption type wherein a refrigerant fluid and an absorbent fluid are used, and involving a generator-absorber section, with means for alternately heating and cooling the same, andan evaporator section, communicative means for conveying refrigerant fluid between the sections and which means is necessary to a complete operative refrigeration cycle, and means for liquefying fluid delivered to the evaporator section; of a conduit independent of said communicative means for transferring absorbent liquid remaining in the evaporator section `at the end of each cooling period to the generator absorber section at the beginning of the following heating period, said conduit having its receiving end opening into the residue liquid collecting portion of the evaporator section and its opposite end liquid sealed in the. generator-absorber section at the begin-y ning of the heating periods, said conduit being out of communication with the liquefying means excepting through the evaporator section and having its intermediate4 portion at communicative means for automatically returning any absorbent liquid remaining in the evaporator-receiver at the end of a cooling period from said evaporator-receiver to the generator-absorber during the early stages of the next heating period, such returning of theliquid being initiated by a rise in pressure in the system when the generatorabsorber is heated.

15. The combination with refrigeration apparatus ofothe intermittent absorption type wherein a refrigerant fluid and an absorbent Afluid are used, and comprising a closed system involving a generator-absorber section, an evaporator section, and communicative meansv for conveying refrigerant fluid between the sections in the attainment of a complete operativerefrigeration cycle, together with means for intermittently supplying heat to the generator-absorber section; of a conduit for recovering absorb.

ent fluid carried over into the evaporator section and returning it to the generatorabsorber section, the flow of absorbent fluid through said conduit being initiated by a change in pressure in the system,c said conduit being capable of receiving refrigerant fluid from the evaporator section and being in part exposed to a temprature sufficiently high to vaporize or maintain in vaporized condition any refrigerant fluid gaining access to the part of the said conduit so exposed whereby, upon the passage of refrigerant fluid through said conduit, the same will be vaporized and interruptothe flow of liquid through the conduit.

16. The combination with refrigeration apparatus of the intermittent absorption type wherein a refrigerant fluid and an absorbent fluid are used, and involvinga generator-absorber section, an evaporator section, and communicative means for conveying refrigerant flufd between the sections in the attainment of a complete operative refrigeration cycle, and means for intermittently supplying heat to the generator-absorber section; of a conduit for returning to the generator-absorber section liquid in thev evaporator section at the beginning of the heating period, a part of said conduit being so situated as to cause it to reach a sufficiently high temperature after the beginning of the heating period to vaporize liquid refrigerant entering said part of the conduit thereby to interrupt the flow of liquid through the conduit and prevent the return of liquid thereafter.

17. The combination with refrigeration apparatus of the intermittent absorption type wherein a refrigerant fluid and an absorbent fluid are used, and comprising a closed system involving a generator-absorber section, an evaporator section, and communicative means for conveying refrigerant fluid between the sections in the attainment of a complete operative refrigeration cycle, together with condenser means and means for intermittently supplying heat to the generator-absorber section. the portion of each cycle during which the heat supplying means is effective being known as theheating period the latter part of which constitutes a condensing phase; of a conduit for returning to the generator-absorber` section liquid in the evaporator section at the beginning of each heating period, a part of said conduit being so situated as to cause it to reach a suficiently high temperature during the condensing phase to vaporize liquid refrigerant entering said part of the conduit thereby to interrupt the flow of liquid through the conduit and prevent the return of liquid thereafter.

18. The combination with refrigeration apparatus of the intermittent absorption type wherein a refrigerant fluid and an absorbent iuid are used, and comprising a closed system involving a generator-absorber section, an evaporator section, and communicative means for conveying refrigerant fluid between the sections in the attainment of a complete operative refrigeration cycle, together with means for intermittently supplying heat to the generator-absorber section, the portion of each cycle during which the heat supplying means is effective being known as the heating period; of a conduit for returning to the generator-absorber section liquid in the evaporator section at the beginning of the heating period, a part of said conduit being situated in heat exchanging relation to the aforesaid communicative means so that said part of the conduit will reach a sufIicient-ly high temperature during the early phase of the heating period to vaporize liquid refrigerant entering said part of the conduit thereby to interrupt the flow of liquid through the conduit and prevent the return of liquid thereafter.

In testimony whereof, I hereunto aix my signature.

DAVID F. KEITH.

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