US2380537A - Means for refrigeration - Google Patents

Description

M. H. MCMECHAN 2,380,537

MEANS FOR REFRIGERATION Filed Dec. 20, 1958 4 Sheets-'Sheet 1 July 31, 1945.

S my N ATTORNEY vJuly 315-1945- M. H. Mcm-:CHAN 2,330,537

` MEANS FOR RVEFRIGEATION Filed Dec. 20, 41958 4 Sheets-Sheet 3 Y. INVENTOR MAUR/cf M .Mc-Mec//M ATTORNEY Patented July 31, 1945 UNITED STATES PATENT OFFICE MEANS FOR REFRIGERATION Application December 20, 1938, Serial No. 246,837

Claims.

This invention relates to refrigeration and more particularly concerns an improved refrigerating method and system employing an evaporable refrigerant of the type that sublimes directly from the solid to the gaseous state, such as solid carbon dioxide.

When solid carbon dioxide evaporates or sublimes to the gaseous state, heat is absorbed at such a rapid rate that the medium to be cooled. which may be the space within a refrigerator cabinet, is quickly reduced to a temperature far below the desired range. In accordance with the present invention, it is proposed to provide a refrigerating method and system in which the cooling effect produced by the gasification of solid carbon dioxide or like material is effectively and economically controlled whereby the medium to be cooled can be maintained at the desired temperature and the evaporation of the refrigerating material can be suitably retarded in conformity with the refrigerating load imposed. To this end, the system of the invention includes a conduitcircuit for conducting brine or other heat transferring liquid to low freezing point in successive heat exchanging relation kwith the evaporating carbon dioxide and the medium to be cooled, and further includes improved means for controlling the rate of flow of the liquid through this circuit.

A further primary object of the invention is the provision. of a system of the type described which is portable and which may be used on trucks, buses, railway cars and other conveyances where it is subjectedr to considerable vibration and agitation. To this end, the improved system employs a conduit circuit for the heat transferring liquid such as brine, which circuit is entirely closed and thereby completely isolated not only from the atmosphere but from the evaporated gaseous refrigerant as well. The system of the invention incorporates mechanical means such as a pump or impeller for positively circulating the heat transferring liquid through its closed circuit, and this pump is driven by a mechanical power producing means motivated by the pressure of the refrigerant gas evolved from the solid refrigerant as it evaporates to produce the heat absorbing effect.

Another object of the invention isv the provision of a system of the type described incorporating improved means for controlling the circulation of the brine or other heat transferring medium in accordance with the temperature of the cabinet or other medium to be cooled. The solid refrigerant material is confined in a sealed chamber from which the gas under pressure is carried by a suitable duct to the power producing means which drives the liquid circulating pump. In accordance with the invention, the circulation of the brine or liquid is controlled by a thermostatic device which regulates the gas pressure delivered from the solid refrigerant chamber to the pump driving means. In a preferred embodiment of the invention, the thermostatic means acts, when the cabinet or other medium has been cooled to the desired low temperature, to vent the duct supplying gas to the pump driving means whereby the pressure available to operate the pump is reduced and the pump is stopped. In some cases, it is preferred to provide suitable means for restricting the flow of gaseous refrigerant from the solid refrigerant chamber when the duct supplying the pump driving means is so vented. In this manner, the gas pressure in the solid refrigerant chamber is not unduly reduced when the operation of the pump is discontinued or retarded by venting its gas supply duct.

Various additional objects, advantages and characteristic features of the invention will be pointed out or will become apparent in connection with the description cf certain embodiments thereof.

In accomplishing these and other objects of the invention, I have provided the improved details of construction, the preferred and alternative forms of which are illustrated in the accompanying drawings, wherein- Fig. 1 is a vertical, cross section of a refrigerat. ing plant embodying the present invention in one of its preferred forms.

Fig. 2 is a vertical cross section, taken on the line 2--2 in Fig. 1.

Fig. 3 is an enlarged sectional detail through the cooling coils, as seen on the line 3-3 in Fig. l, particularly illustrating the overlying plate for supporting the refrigerant thereon.

Fig. 4 is a similar cross sectional detail, showing coils of a different cross sectional form.

Fig. 5 is a detail of the lid of the refrigerant chamber, showing its clamping and sealing means.

Fig. 6 is an enlarged, central cross sectional view of the refrigerant pump.

Fig. 7 is a view illustrating details in section of the pump and the gas control valve with its thermostatic control.

Fig. 8 is a plan view of the cooling coils, as disposed in the bottom of the refrigerant chamber.

Fig. 9 is a view illustrating an alternative, cnepipe system, utilizing pump action for recharging the cooling coils.

Fig. 10 is an enlarged sectional detail of the valve devices employed. for controlling flow of gas to the `pump.

Fig. 11 is a sectional view of a pump of alternative form.

Fig. 12 is a sectional detail of still another a1- ternative form of pump, adapted for continuous circulation of the liquid medium.

Figs. 13, 14 and 15 are diagrammatic illustrations of alternative forms of construction, wherein the generated gas is discharged directly into the liquid circulating pipes to create a forced circulation in the recharging of the cooling coils.

Brieily described, the present systems are designed to be associated with cabinets of usual types employed for refrigeration, adequately insulated against heat transfer from external sources, and provided with suitable air-tight doors to give access to the interior thereof. It is also contemplated that the front wall of the cabinet be equipped with glass windows for display purposes as is common in many refrigerators of the market types.

Within the cabinet is a compartment for the solidied refrigerant, suitably insulated from the storage space and Within which compartment is disposed, upon its bottom or floor, a coil of tubing within which the liquid medium or brine" is circulated for cooling. A pump is interposed in the pipe system of the circulated liquid medium, and this pump is operated by the gas generated by the evaporation of solidified refrigerant, as it takes on heat from the coil.

The refrigerant compartment has a lid, or cover, ci substantial dimensions to permit easy and quick recharging of the compartment, and the lid may be applied in an air-tight seal to prevent the escape of the generated gas.

Referring more in detail to the drawings- As seen in Figs. 1 and 2, the present mechanism is embodied in a cabinet, designated in its entirety by the reference numeral it), comprising outer and inner wall linings l l and I2 of sheet metal between which is disposed a ller of suitable heat insulating material I3. This cabinet, as Seen in Fig. 2, is provided in its top wall with an opening I4 to which is fitted an air-tight door i5: the door being hinged at I6 to open upwardly, and a latch being provided, as at I'l, to hold it tightly closed.

In the present instance, I have shown the cab inet as being provided with a display window 2li in its front wall, and this window comprises a plurality oi glass plates a, 2Gb and 2Go, spaced apart so as to provide intermediate spaces, whereby to minimize heat transfer from the exterior to the interior of the cabinet. The spaces between the glass plates preferably are lled with carbon dioxide gas to eliminate frosting of the glass.

Disposed within the refrigerator is a metallic container, designated in its entirety by the reference numeral 25. This container is here shown to be ci rectangular form, but may be round or of other suitable shape, and it is constructed with outer and inner rvall linings 26 and 2l, of sheet metal, between which is disposed a layer of heat insulating material 28. it will be noted, by reierence to Fig. l, that the outer lining is formed th an lnturned flange about its top portion, then is tmned upwardly in line with the inner and that a lid le removably disposed upon the extended edges; the lid having depending flanges that overlap these edges, and within the flanges is tted with a sealing gasket 3| of rubber or other suitable sealing material, as noted in Fig. 5.

Fixed permanently to the inturned upper edge flanges of the outer wall lining, at opposite sides of the lid :iii are upwardly directed brackets 32, provided with laterally opening notches 33, as noted in Fig. 5, wherein the opposite ends of a lid clamping rod 34 are rotatably contained. As seen in Figs, 1, 2 and 5, this clamping rod 24 is substantially straight, and is provided near its ends With eccentrically formed cam portions 35, adapted to be pressed into clamping contact with at leaf springs 35 disposed against the top of the cover 30 near opposite edges, to press the cover tightly against the top edges of the container walls 21. This clamping action is effected by rotation of the rod through the leverage provided by a handle 35 that is fixed to the rod at a medial point, and extends perpendicularly to the formed cam portions 35,- as shown in Fig. 5. It will be understood that with the compartment 25 sealed, gas generated by the evaporation of the solidified refrigerant will be confined under pressure.

A gas discharge tube; or pipe, 40 leads from the compartment 25 to a valve housing 4i, which contains a needle valve controlled by a thermostat; the thermostat being designated in its entirety lnFig. 2 by the reference numeral 42. A pipe 43 leads from the other side of the valve housing 4l into the bottom, and right-hand side of a pump as seen in Figs. 1, 2 and 7; the pump being designated in its entirety by reference numeral 45.

Disposed within the container 25, adjacent the bottom thereof, is a pipe coil 50. This comprises a plurality of loops formed by a continuous pipe and all loops lie in the same horizontal plane. As seen in Fig. 3, a at metal plate 5l overlies the coll and supports the solidied refrigerant thereon. A pipe 52 extends from one end of the coil 5i), through theY rearward wall of the compartment 25, and is then directed upwardly through the insulation 28 and at its upper end opens into the bottom of a storage tank 53 containing the liquid refrigerant or brine Also, a pipe 55 leads irom the top portion of the brine tank into the top left-hand side of the pump 45, and the circulating circuit for the brine is completed by a connecting pipe 5E leading from the other end of the pipe coil 5D, and directed upwardly thro gh the insulation 2B and connected to the bottom lefthand side of the pump, as seen in Figs. 2 and 6.

As seen in Figs. l and 3, the coils 50 lle substantially parallel, in close relationship to each other, and the plate 5i is disposed upon or adjafcent their upper surfaces so as to provide for an even heat distribution or transfer to the solidified refrigerant.

Fig. 4 discloses, in cross section, an alternative form of coil construction. wherein pipes 5ta are formed in rectangular or square cross sectional area and disposed parallel to each other in close relationship.

In Fig. 6, I have illustrated the pump 45 in de tail, this pump comprises opposite side portions 6U and 6I of cup-like form and of like size, and disposed in edge to edge relationship, to form an enclosure. A flexible diaphragm 62 is disposed between the ilanged edges of these parts G0 and Si which are joined tightly together by bolts 23 through the flanges.

It will be noted that there is a hinsedly mount-- ed flapper valve 58=withinthefshell 6D, to `automatically close theoutlet of the pipe 56- against anyX return ilow` therein `of thebrine, as will be subsequently explained.. Also, f if found desir"- able, aback check valve,59 may be applied to the inlet into pipe 55 to cooperate with the valve 58.

Extended rcentrally through the -diaphragm 62 is arbolt B held bya nut B6'. The lbolt head secures a lever '61,A onv the right-hand side of the diaphragm and a washer 68'is heldibeneath the nut on the other side; the washer, in turn, vmounting a coiled spring 69, whichbears against thebasewall ofthe corresponding section 69 to press the diaphragm toward theopposi-tewall.-

The section 6|, closing theright-hand side of th'e pump, isprovided withea port 10, through which the gas generatedby evaporation of the solidified refrigerant isexhausted in Aoperation of.the.. pump. This port 10:. is fittedwith a sleeve .1| formed at its inner end with a valve seat1l, against which a ball valve 121s adapted toseat-.toseal the port. The ball 12 is actuated froma closedL-position to open position by the actionY of ,a mechanism including a pair` of formedlevers 15 and 16.wl1ich are mounted to oscillate on, and extend, respectively, upwardly anddownwardly from a horizontal hinge pin 11 that is xed in a. bracket 18 that-is rigidlyxed tothe` wall just below the port'19.

It will be vnoted that the lever 15 xedly mounts a r,coiled springll contained within a shallow cylindrioal cup 8| that isxed on the side ofthe lever facing the port 10; this spring mounts vth'e balland serves to yieldably hold it against the valve. seat 1| whenin closed position. The cup 8| serves also toretain the ball 12 against displacement from operating position when the valve is Open.

Thexlevers 1.5 and 19 .are provided at their swinging ends with laterally extending ears 15a and 16a respectively, connected, as seen in Fig. '7, by, coiled springs 85. It will be noted also that thelevers 15 and 19 are provided at theirinner ends with' short, angularlyV extendingy legs 15b and 1Gb respectively, which engage the base of the bracket 18 and thus operate to limit the outward travel of these levers when actuated by springs 85 to position to openthe valve 12. It Will be notedthat the bracket 81 is of U-form and has its outer end extended to a position underlying the swinging end of lever 16 so that movementof the diaphragm Will cause movement of the lever, for a purpose presently understood.

By reference to Fig.. 7, it will be noted that the needle valve 4| is operated between open and closed positions by the thermostat 42. The valve housing is provided with a threaded mounting shank 4|@ that extends into the housing 90 of the th'ermostat, and this shank contains a needle valve stem 9| which extends into the thermostat housing. This valve mechanism may-be of conventional construction, and is adjusted for proper operation and is then locked in place by the lock nuts 92Which are adjustable 0n the shank; it being understood that seating of the stem 9| is effected by means of a bi-metal thermostatic arm 95a so disposed for action against the needle valve member 9| .that by upward pressure of the thermostaticarm 95a, the needle will close a gas relief outlet 4|b` in the valve, thereby to cause all the gas to be deliveredto the pump through pipe 43. However, when the temperature is Sunicientlyl loweredthe Vpressure on stem9| willbe l ably through the housing wall to the exterior and there is provided with an indicator arm 91 overlyinga calibrated strip 98 xed on the housing. It Will here be stated that the shaft 96 which, on

. its inner end, mounts the bimetal spiral and yon its end, the arm 91 istigh't enough in its mounting so as not to be moved or rotated by the force of the spiral when it expands due to low Itemperatures but may be moved manually by the arm 91 so as to set the thermostat to operate the valve at any desired temperatureas will be determined by the position of the arm 91 relative to the calibrated strip.

It is desirable in the use of this apparatus that means be provided forlcontrolling or limiting the flow of gas to the pump and for stopping flow when pressure-in the refrigerant container falls below a predetermined amount; the reason for this being that when the gas pressure within the container is highthere is a possibility of its compressing the spring S9 in the pump 45, and holdingy it compressed. This, ofcourse, is only possible when the gas pressureis greater than the expansion force of the spring. Also, by closing the discharge line at a certain low pressure, such as a 2M is adapted to close; the ball being actuated yieldably to closed position by a coiled spring 2| 5. The retaining pressureof the spring may be varied by the adjustment of a stem 2|S that is threaded through al cap 2|9 aDpIled to the valve housing and which mounts the spring at its inner end.

. The adjustment of the stem obviously makes it possible rto determine the pressure at which the valve will close. The valve 2| is provided with a cap member 229 threaded into the valve housing and is provided withr a threaded adjustable valve stem. 22|, which comprises at its lower end, a needle valve member 22 la adapted to progressivee ly restrict the passage 222, through the valve housing, until` it is approximately closed. By such a provision, the flow of gas to the pump may be regulated or controlled with reference to a maximum high pressure through the valve 2| l, in that the flow is restricted and there is not ample time to build up, a pressure greatenough to hold the spring G9' compressed, thereby insuring continuous and uninterrupted operation of the pump when the thermostatic by-pass is closed.

The use of the device as described in the foregoing is as follows:

To charge the container 25 with the refrigerant, or dry ice, the bar 34 is rotated by proper action of the handle 36, to relieve the pressure of the formed cams35-on the lid 39, and permit removal of the rod ends from the slots in the brackets 32. The lid 39 may then be removedand the dry ice placed in the container whereupon the lid must bereplaced and thercontainer sealed.

It will here be stated that the insulation 28 around the ice chamber is a very essential feature of construction in that the refrigerant used is of such low degree of temperature; namely, about 109 C., below zero, that without it, the storage chamber in the cabinet would eventually reach approximately the same temperature, which would be much too cold for ordinary usage.

The pipe system and storage tank are assumed to be filled to proper level with a suitable liquid refrigerant or brine, which normally fills the lefthand compartment of the pump, as seen in Fig. 6.

As the dry ice absorbs heat from the plate I and coils 50, it evaporates, and the resultant gas builds up a pressure within the container and also in the pipes 4U and 43, leading to the pump 45. Assuming that needle valve 9| is seated as in Fig. 7, it will be understood that, as this pressure increases, it pushes the diaphragm 62 from the position shown in Fig. 6 to the opposite side, thus to dispel the brine through pipe 55 into tank 53. The valve 58 closes automatically with this operation, and valve 59 opens. Then, when the diaphragm comes to rest, the 4valve 5S closes. As the diaphragm is moved by the gas pressure to the left side of the pump, the'upturned end portion of the lever 61 lifts the lever 1B and when the lever 16 passes over its dead center position, the springs`85 cause the valve mechanism to snap open, throwing the valve ball 12 away from the port 10.

Then, when the valve ball 12 is lifted from valve i seat 1 I', the gas confined in the pump chamber is exhausted through port 10, and the spring 69 will then act to move the diaphragm 62 back to the original position. Incident to this return movement of the diaphragm, the head of bolt 65 will engage the lever 'I6 and move it back across the dead center line in such manner as to cause the I valve mechanism to close the valve 12 against its seat, thus to close the pump for a subsequent building up of gas pressure therein.

It will here be mentioned that I do not confine the valve mechanism to the ball type shown, 'but fully anticipate that a needle valve may be used with satisfactory results. Therefore, in the appended claims, the .use of the term valvein referring to this particular apparatus is to be construed broadly as any suitable type valve of an equivalent nature, for closing port 1B.

This cycle of operations is repeated periodically, thus drawing the brine from the coils 5i? into the diaphragm pump, and then forcing it into the tank 53. Because of this pumping action brine is drawn from the tank 53 into the coils 50 and is there cooled. The heat extracted from the brine `causes the dry ice to evaporate to generate gas. The plate 5I that overlies the coils 5B, in contact therewith, provides for an even dissipation of heat from the coils, and as the dry ice is evaporated evenly by this plate 5I, it feeds down evenly. It is therefore obvious that the interior of the storage cabinet may be cooled rapidly, in that the warmer the brine is, the faster the dry ice will be evaporated, thereby speeding up the operation of the diaphragm pump.

Furthermore, when the temperature of the storage cabinet reaches the temperature for which the thermostat is set, the needle valve 9| will be opened by movement of the extending portion 95a of the bimetal lever. The opening of the port Hb bypasses the flow of gas and consequently stops the operation of the diaphragm pump. When the temperature rises suiliciently to cause the thermostat to close the port Mb, pumping is resumed. However, there are certain possibilities of the pump being rendered inoperable by a very high gas pressure being built up in the container 25; for instance, subsequent to its being recharged with a fresh supply of dry ice, and the whole interior of the cabinet being at a comparatively warm temperature. On such occasion, the heat transfer is rapid and the dry ice evaporates rapidly, and such pressures might be high enough as to prevent the spring 65 from operating the diaphragm, as previously stated with reference to the pump operation.

The regulating valve 2li may be adjusted so that the flow of gas therethrough is slow enough that a pressure great enough to hold the spring 69 compressed does not have suiiicient time to build up, thereby insuring a continuous and uninterrupted pumping operation.

Furthermore, the pressure valve 2H) retains a predetermined gas pressure within the container, so that when the port 4 lb in the by-pass valve is opened, the gas pressure in ythe tank will be reduced to the aforestated predetermined value, the excess gas escaping. Then, when the needle 9| is actuated by the thermostat to close the port lill), the pump will operate substantially immediately, upon 'any increase of gas pressure, and thereby eliminate the period of inoperation necessary to build up, by evaporation of the dry ice, the gas pressure that is retained in the compartment 25 by the said valve 2IU. It is obvious that a more efficient pumping and circulating cycle is thereby insured by these two valves, and it is also obvious that a regular or even temperature may' thus be maintained with this type of refrigeration, and that a very broad range of refrigerating temperatures is available.

In Fig. 9 is diagrammatically illustrated an alternative arrangement known as a one pipe system. It is to be understood that in this system, the compartment 25 or container for the evaporable refrigerant referred to as dry ice may be like that previously described in principle, and the tank for storage of brine also may be like that previously described. However, only a single pipe l extends from the brine tank 53 to the cooling coils 50 and a pipe lill connects the coils 50 with the liquid receiving side of the diaphragm pump 115; this connection corresponding to the pipe 5S, shown in Fig. 6, but with the back check valve 58 and the pump outlet pipe 55 eliminated. A gas pipe H33 leads from the container 25 to the gas side of the pump which would be as illustrated in Fig- 6.

To control the iiow of gas, a thermostatically controlled Valve device corresponding to the parts 4I and 42 of Fig. 7, would be applied to pipe 103.

Thus, it will be understood that in this alternative system, the flow of liquid has a reciprocating action rather than of circulation, for the diaphragm pump under the iniiuence of generated gas, will operate to intake and then expel from the pump the cooling liquid through the pipe system, thus to periodically recharge the coils of the system with brine from the tank; the brine thus being kept cooled by the refrigerant.

In Figsl l1 and 12 are illustrated two more alternate means for `forced circulation of the cooling brine through the medium to be cooled. With reference to these alternate forms of construction of the brine pump, it will be understood that the pump 45 as in Fig. 6 provides what may be termed an intermittent movement or circulatinuous flow system.

Referring now "to '-Fig. l1, the pump mechanism'is'designated :in its entirety by the reference numeral 225 and it comprisesafcylindrical housing 226rcontaining a reciprocating 'piston 221, provided with a piston rod 228 slidably disposed wi'thina". bearing`229zn ,the :upper end wall of the housing. This rod is provided with shoulders 228a and 229D which operate to limit the reciprocal ton 221 is a compression spring 230, adapted to lift the piston within the cylinder, as will be subsequently explained.

It will be noted that the pipe 43 which delivers the gas from the refrigerant container 25 to the pump is operably connected to the cylinder 226 above the piston 221, and that the brine pipes 56 and 59 are operably connected to the cylinder 226 below the piston 221l and also that there is a back check ap valve 23| adjacent to the connection of the` pipe 56, and a back check flap valve 232 adjacent to the connection of the pipe 56 to provide a one-way flow of the brine.- The same valve mechanism illustrated within the diaphragm valve in Fig. 6 is associated with the reciprocating piston pump, and it will not here be referred to in detail. However, any other valve mechanism may be used that will accomplish the desired action.

An upwardly projecting boss 232a on the upper side of the piston 221 is adapted to contact the valve lever arm 16 and operate the valve ball 12 to a closed position, and a chain connection 233 is substituted for the lever 61 to open the valve at the lower limit of travel of the piston 221, this chain being connected tc the lever 16 and to the boss 232e.

In the other alternative form illustrated somewhat diagrammatically inv Fig, 12, a turbine 235 operates a centrifugal pump 236 that is connected thereto by a common shaft 231. The gas vdelivery tube 43 is connected to the turbine, so

that the gas is delivered through a nozzle or orifice 238 and impinges upon the vblades 239 of the turbine. The operation of the centrifugal pump 236, as well as the turbine 235'is well known, land therefore a further description is deemed unnecessary. However, it will be pointed out that in the use of either of the pumps 45 or 225, the circulation of the brine is intermittent, whereas when the centrifugal pump 236 is in connection with a suitable gas propelled driving means, such as the-turbine 235, the circulation of the brine is a steady or continuous flow while the pump is in operation.

In Fig. 13 is illustrated still another modification of the system; this system eliminating the gas actuated pump. In this arrangement, the coils 50 are supplied with liquid from tank 53 through a pipe |06, and the liquid delivered back into the brine tank through a pipe |01. A gooseneck turn, or vertical loop |08 is provided in pipe |00, and this contains a back check valve |09. A gas connection is provided vthrough a pipe I Il] between the container 25 and the top of the gooseneck between the back check valve and coils 50. This gas connection is equipped with a back check travel of the piston. Beneath the pispipe'- |1| 0, through coils''50, and pipe |2,l in the topV of tank 53.

- up in the -pipe system; fthe liquid, displacing finnally dischargingit finto the Atank through-pipe 11.01.

"valvejdesignatedat |,`r for'preventing back flow 'of the liquid into 'thecontainer 25;

In this `systemghthey gas discharged from container 25 isforced into the pipe coils 50 through |01 into tank through a ventr as at VThe operation of this "When gas pressure is built it forces, ahead of thegas, it from thercoils 50, and

53, and -is 'expelled i finally system `is as'fcllows:

'Whenl thebrine is thus discharged,` the.A gas escapes into tank 53 and'thereliefiof' .this pressure in the coils permits the back check valve |09 to open, thus allowing the coils to again fill with fresh brine from the tank through pipe |06.

In this latter system, a thermostatically controlled valve device ||3 controls the admittance of brine into pipe |06; thev valve closing when a desired temperature has been reached andv opening when the temperature rises above this desired degree.

In Figs. 14 and l5 respectively there has been illustrated certain means for preventing syphoning of liquid, or gravity fiow of liquid, back from the tank 53 into the compartment 25. In Fig. 14, an auxiliary tank is provided alongside of tank 25 and of sufficient volume to hold the normal supply of liquid in tank 53. In the event the liquid syphons back, it will be retained in tank |90 and not flow into the container 25. Then,

when gas is created in container 25, the liquid -in tank |90 will be forced up into tank 53. Connections |9| and |92 are provided between upper and lower ends of tank |90 respectively with the container 25 and pipe |93 to the tank 53.

In Fig. l5 is a similar device wherein a tank is provided alongside of tank 25 and is connected by a very small gas port |96. A gas jet nozzle |91 opens from the bottom of tank |96 into pipe |98, leading to tank 53. The theory here is that while port |96 is large enough for gas delivery, it is too small for liquid to flow back through to any extent While the tank 25 is being recharged.

Having thus described my invention, what I claim as new therein and desire to secure by Letters Patent is:

1.In a refrigerating system, a medium to be cooled, a closed container for an evaporable refrigerant, a gas vented tank containing a supply of liquid cooling medium, a pipe system connected with the tank providing a one-way liquid circuit passing in heat exchange proximity to the medium to be cooled and to the refrigerant, a back check valve in the pipe line at one side of the refrigerant container, and means for discharging gas under pressure from the container into the pipe system at one side of the valve to dispel the cooled liquid therefrom into the tank; said back check valve being adapted to open when pressure of gas is removed by reason of its exhaustion into the tank, to permit recharging of the pipe system with liquid from the tank.

2. A system as in claim 1, wherein a thermostatic valve controls the admittance of the liquid from the tank into said pipe system.

3. In a refrigerating system of the characte disclosed, a medium to be cooled, a closed container for an evaporable refrigerant, a storage tank for a supply of liquid cooling medium disposed above the said container, a liquid circuit connected at its opposite ends to receive from and deliver liquid into the tank, and extending through the medium to be cooled `and through the said refrigerant container for heat exchange, a reservoir located below the level of the storage tank, a gas delivery connection between the refrigerant container and top of the reservoir, and a. gas connection from the reservoir into the circuit for delivery of gas under pressure to create i circulation of the liquid in the circuit; said reservoir being adapted to retain any liquid that should be syphoned or otherwise caused to flow thereinto through its gas connection with the liquid circuit incident to lack of gas pressure in the refrigerant container.

4. A system as in claim 3 wherein the gas connections between the closed container and liquid circuit are so located relative to vertical spacing that gas pressure created in the closed container Ywill operate on the liquid in the reservoir, as to displace it back into the liquid circuit and storage tank.

5. Av system as in claim 3 wherein the gas connecting passage between the closed refrigerant container and reservoir is relatively small, thereby to greatly retard any ilow therethrough of liquid.

MAURICE HANDSCOM MCMECHAN.

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