US2383486A - Refrigeration mechanism - Google Patents

Description

RICHARD J. Pznsnuvs CLARENCE H4 flouanvfim (/2. E0 WARD .D. PATTON ROB$ER r CARA WA Y Filed Feb. 8. 1939 R. A. ISENBERG EI' AL REFRIGERATION MECHANISM Augz's, 1945.

ATTORNEY NM mm Patented Aug. 28, 1945 2383, 186 REFRIGERATION MECHANH$M Ruoli' A. Isenberg and Richard S. Perez, Los

Altos, and Clarence Van Houdcn g, lira, Edward D. Patton, and tart Caraway, San Francisco, Calif., assignors to Perishables Shipping Equipment lompany, a corporation of Nevada Application Febru t, 1939, Serhi No. 255,244

(i. se -eat) 12 Claims.

The present invention relates to means for exchanging heat in order to lower the temperature within a compartment, for example a refrigerator car or other enclosed refrigeration space, and is particularly concerned with a refrigeration mechanism which is designed to utilize solid carbon dioxide, hereinafter-referred to as "dry ice.

An object oi. the present invention is to provide a refrigeration mechanism which is entirely selfcontained and self-crating, without requiring the utilization of additional heat energy for its operation.

Another object of the present invention is to provide a refrigeration mechanism, in which the heat-absorbing medium is also effective to provide mechanical work.

Another object of the present invention is to provide a refrigeration mechanism up Dry lice in which substantially constant refrigeration temperatures are maintained.

Another object of the present invention is to provide a refrigeration mechanl of simple-and reliable characteristics.

The foregoing and other objects are attained in the embodiment of the invention illustrated in the drawing in which Fig. 1 is a side elevation of a refrigeration mechanism constructed in. accordance with our invention, parts being broken away to show the interior construction;

Fig. 2 is a cross-section on a vertical median plane, through the motor pump unit, of the re frigeration mech we Fig. 3 is adetaii in elevation showing a modilied circuit connection for the refrigeration mechanism.

"In its preferred form, the refrigeration mechanism of the invention includes a closed heat exchange circuit through which a heat-exchanging fluid is circulated by a pump, so that in one part of the circuit heat is absorbed and in another part of the circuit heat is released to a sublimating refrigerant the gas from which operates the l D- I In a. preferred installation of the refrigeration mechanism, which is described herein as typical although the mechanism can be adapted to oper-' ation in very difl'erent'environments and in many different forms, the structure is installed in a refrigeration space, such as the interior of a. reirigerator car, containing produce or other mate rial to be refrigerated. In order to reduce the temperature of the space there is provided aheatabsorbing coil 6 or a. series of such coils which can be of any desired construction suitably mounted, but in the present instance the coil structure incorporates a plurality of sinuous passes l and t to aflord a portion cfa circuit for aheat-exchange fluid, preferably a fluid which will remain in liquid form at extremely low temperature, i. e. F. and also remain a liquid at ordinary atmospheric temperatures, such as alcohol, oil and the like. The heat exchange fluid passing through this circuit is here termed the secondary refrigerant. By using such a liquid,

instead of a substance which becomes a gas at ordinary temperatures, the necessity of gas proof lines and connections, back pressure valves and such is eliminated. However, the use of one of the well known fluids such as sulphur dioxide,

ethyl chloride, freon, or the like, is likewise within the scope of this disclosure. The absorber coils t are of adequate surface to absorb sumcient heat from the space in which they are located to main the desired low temperature therein as long as the exchanging fiuid'is circulated therethrough. It is'contemplated that a plurality of absorber coils t may be connected together in the system.

One of the elements of the system is the closed container it. This container is mounted on supporting feet it in any appropriate location, either outside of or preferably within the same refrigrequired. The container is protected against thermal transfer by a surrounding layer of insulation l6.

Disposed within the container I3 is a sublimating refrigerant, such as blocks It of Dry Ice which material is termed the primary refrigerant. These blocks are introduced through a. charging door ll which can be secured against the internal pressure, and the blocks to rest upon the coil I? either directly or upon a plate is interposed between the Dry Ice and the coil. It is obvious that the coils l2 may also-be arranged vertically or in any other suitable manner. In either event, a. ood thermal relationship is established so that heat is readily released from the coil H to the Dry Ice l6.

The absorption of heat by the Dry Ice blocks it causes sublimation of the carbon dioxide, and

. the gas evolved increases the pressure within the tank i 3. It is preferred that this pressure he kept at a value not to exceed approximately lbs. per square inch, and hence there is disposed on the container l3 a relief valve I9 which is adjustable to discharge through pipe 2| 9. sumcient quantity of gas to maintain the pressure within the tank at a selected value. The gas released from the relief valve l9 can either be discharged into the same enclosure within which the heat-absorbin coil 6 is disposed, to the insulation surrounding the space to be refrigerated or to atmosphere'gas may be desired. Certain commodities are beneflcially affected by the CO2 gas, whereas others are detrimentally affected thereby, and whether or not the gas from the relief valve I9 is diverted to atmosphere depends upon its effect upon the commodity being cooled. The device is made so that the adjustment can be made instantly depending upon the commodity cared for at the time. solid carbon dioxide passes immediately into a gas and increases in volume approximately 500 times at a like temperature. Thus pressure is built up rapidly and in the present system there is always a plentiful supply of the gas.

The heat-exchange fluid flows in a closed circuit and for convenience in description the flow will be described as starting from the balancin tank or reservoir 36 located adjacent the closed container |3. The fluid is here shown as leaving the tank 36-through ducts 33 and 34 and passing through check valves-32 to the connections 21 and 26 of the pump mechanism, generally designated 29, disposed on a bracket 3| mounted on the tank l3 or placed in any other suitable manner. The pump mechanism 29 establishes the.

circulation of the fluid through the system. From the pump unit the fluid, having had its pressure increased, is discharged through check valves 26 into ducts 23 and 24 which unite to form duct 22-conveying the fluid to coils I2.

As the heat-exchange fluid within the coils loses its heat to the Dry Ice and its temperature is lowered, it flows from the coils l2 through an outlet pipe 9 and fitting into the heat-absorbing coils 6 and through the sinuous passages 1 and 6 thereof. The fluid then fiowsfrorn the outlet 46 through the return line 39 to, the balancing tank or reservoir 36. The balancing tank 36 shown as supported on brackets 31 may have a relief valve .38 and is a closed surge chamber to which the return pipe 36 conducts the heatexchange fluid back from the outlet 46 of the coils 6, thus completing the closed circuit including the pump 26 through which the heat-exchange fluid is circulated, the heat-absorbing coils 6, and the heat-releasing coils l2.

It is of course-obvious that the closed cir-- cuiatory system may eliminate the tank 36. In this event the ducts 33-and 34 unite and carry the flow directly from the pipe 39.

In accordance with the. present invention, means are provided which do not require the addition of any heat or other energy to the system but rather utilizes the gas sublimated from the Dry Ice for motivating or driving the pump which circulates the heat-exchange fluid. The pump shown herein as illustratingthe invention is a positive double-acting displacement pump. In.

this way a self-contained unit is provided which operates as long as any refrigerant is available,

which is efficient in that no external heat is added to the system, and which is economical since it' makes a double use of the refrigerant. Furthermore, since the rate of circulation of the heatexchange fluid through the coil 6 or series of coils It is well known that upon sublimation" is a factor which is largely controlling ofth temperature maintained within the refrigerated space, means are provided for regulating the operation of the circulating pump so that a substantially constant temperature can be maintained.

For this reason a pipe 4| is connected to the tank l3 adjacent the top thereof in a good location to receive sublimated gas from the Dry Ice, and pipe 4| is connected to a controlling valve 42 regulated by a thermostat 43 responsive to the temperature of the space being cooled, preferably, although the valve 42 can be manually controlled or can be made otherwise responsive. The gas which flows through the valve 42 is preferably of a pressure not to exceed 15 lbs. per

. square inch, since the relief valve I6 is ordinarily set to maintain substantially such pressure within the tank l3. Gas which passes through the valve 42 flows through an inlet pipe 44 into a passage 46 in the'control body 41 of the motor pump unit 29. This passage 46 opens through a port 48 in a hardened sleeve 49 formin a shuttle valve cylinder. This cylinder is closed at opposite ends by screw plugs 5|, and within the enclosure 50 formed a shuttle valve 52 operates. The valve, when in the position shown in Fig. 2. permits communication between the port 46 and a port 53 through a groove 54 in the shuttle valve,

. duct 51 into a chamber 66.

The chamber 66 is a pump chamber of variable volume defined by a closure cap 69 screwed onto the body 41 and containing a flexible bellows 6| one end of which is held stationarilythe cap 56 by 8- washer 62 the other end of which is clamped between plates 64 and 66 held by a nut 66 on a guide-rod 61. The interior 66 of the bellows 6| communicates with the fitting 21 through a passageway 66, so that as the piston 64 reciprocates, the chambers 66 and 66 complementarily vary in size. Excess pressure in the motor chamber 56, which causes it to expand, correspondingly contracts the pump chamber 66, causing it to expel whatever liquid is therein. Hence, entry of gas from the duct 51 into the chamber 56 drives the piston 64 to the left, as seen in Fig. 2, and expels whatever heat-absorbing fluid is within the chamber 66 into the fitting 21. when the piston 64 is substantially in fullstroke position, the guide rod 61, which slides loosely within a bore in the body 41, acts to prevent. further ingress of gas and torelease the previously used gas.

This is accomplished by a projection 16 on the against the head of and a nut 63 and' rod 61 which encounters a projection 1| on a valve cylinder 11 which is formed within the body 41 and is closed by a screw plug 16. Within the pilot valve cylinde is a pilot valve 16, urged toward one extreme position by a coil pring 6|.

Gas under pressure from the chamber 66, which flows through the passage 16 when the needle valve 14 isunseated, forces the pilot valve 16 to the right, as seen in Fig. 2, closing communication between the cylinder 11 and the .cylinder '46 through a e- 62 which theretofore has been incominunication with the atmosphere through a passage extending from the cylinder 11 to the outside of the body 41. 7 Further movement of the pilot valve 19 to the right uncovers a passageway 84, establishing communication between the- Gas under pressure is thereby delivered to the chamber I formed by the stop llll located on the end surface of shuttle valve 52, thus exerting pressure to move the said valve to the right, as

seen in Figure 2.

Since at this time the corresponding chamber 86 at the other end of the shuttle valve is subject to atmospheric pressure only, the pressure within the chamber 58, being then imposed upon the shuttle valve 52, translates it from its left-hand position as seen in Fig. 2 into its extreme righthand position in such figure. When this occurs, the groove 54 no longer affords communication between the port 48 and the port 53, but rather a land 81 blocks communication between such ports,

' and also a groove 88 establishes communication between ports 89 and 9 l, respectively, in the sleeve 49, so that an exhaust passage 92 is then placed in communication with the interior of the chamber 58. Such being the case, the pressure within the chamber is reduced to atmospheric, but the shuttle 52, having been already translated, remains in its newly translated position.

As the pressure within the chamber 58 drops toward atmospheric, the spring 8| becomes effective to restore the pilot valve 19 to its position as shown in Fig. 2, ready for a subsequent cycle. The shifting of the shuttle valve 52 has opened up communication between the pressure passage 48 and a corresponding chamber on the opposite side of the mechanism." Hence, the cycle starts on the right-hand side of the mechanism to con tract the chamber correspondmg to the chamber 88 and to expel the fluid therein.

During this time the chamber 68 is re-expanded by its own resilience, augmented by a spring 95, to inspirate/additi'onal heat-absorbing fluid and to decrease the size of the chamber 58. Movement'toward the right in Fig. 2 of the rod 6'! releases the needle valve body 12 so that, under the urging of the spring 13, the needle valve It again seats, ready for a subsequent cycle. The cycle of operation continues until the rod 61 is substantially to its extreme right-hand position in Fig. 2 and until the opposite side of the pump mechanism has gone through a comparable cycle, tripping itself at the end of a stroke shuttle 52 again into the left-hand position as shown in Fig. 2, whereupon thepumping cycle repeats.

A manually operable needle 91 is provided. for starting-the mechanism from rest under certain circumstances, by admitting pressure fluid into a passage 98, corresponding to the passage "fund into a passage .99 corresponding to the passage 82, so that the shuttle valve 52 can be moved-into one extreme position by pressure in the event it should be stuck or lodged in an intermediate position due to long disuse. The-needle 91 is operated only for starting the mechanism into operation and is to shift the promptly shut as soon as the devicehas been started.

is shown in Fig. 3. 'l'he duct I III extends from the balance tank 3 5 through a check valve I02 to one chamber. A shunt pipe I03 leads from the duct.

I through a check valve I to the other chamber. A conduit I05, having a check valve Nil therein, leads to the coil l2. With this arrange ment, fluid from'the reservoir 36 is passed through the two pump chambers successively and is then passed into the line 22.

The structure made'in accordance with my invention is particularly eflective as it has no rotating parts subject to leakage and since it operates slowly and smoothly in accordance with the pressure of the entering gas at a rate sufiicient to pump the heat-exchange fluid throughout the heat-absorbing coil 6 so that heat is absorbed at the desired rate to maintain a constant temperature. Pressures as low as from 3 to 8 lbs. per square inch have been found satisfactory as only a comparatively small volume of liquid is moved at any time. Gas which is discharged through the outlet 92 is released either into the compartment or into the atmosphere at a remote point. The pump mechanism operates upon the energy included in the Dry Ice, without necessitating the addition of any heat energy to the system, is substantially leak-proof, and is self-contained and readily replaceable in the event of difliculty. As a whole, the mechanism operates to maintain a desired temperature .by circulating a heat-absorbing fluid which is deprived of its heat by the same refrigerant which furnishes the motive power for circulating it.

We claim:

1. A refrigeration mechanism comprising a closed heat-exchange circuit including heat ab sorbing coils, a heat releasing coil and. a pump for circulating a heat exchanging fluid through said circuit, and a closed container for a sublimating refrigerant in thermal relationship with said heat releasing coil, said pump being operated solely with sublimated gas from said refrigerant.

2. A refrigeration system comprising a closed heat-exchange circuit including heat absorbing coils, a heat releasing coil and a positive doubleacting displacement pump for circulating heatexchange fluid through said circuit, and a closed container for a sublimating refrigerant in thermal relationship with said heat releasing coil, said pump being operated solely by sublimated gas from said refrigerant.

3. A refrigeration system comprising a close heat-exchange circuit including heat absorbing coils, a heat releasing coil, a secondary fluid refrigerant and a positive double-acting displace .ment pump for circulating said secondary fluid circuit for said secondary fluid refrigerant separating the secondary refrigerant from the prifluid refrigerant into thermal relationship with.

said primary refrigerant in a refrigeration circuit, a refrigeration circuit for said secondary refrigerant in thermal relation both with the space to be refrigerated and said primary refrigerant but separating the secondary refrigerant from direct contact with the primary refrigerant and its sublimate, means for operating said pump with sublimated gas from said container and a thermally responsive means for controlling the operation of said pump.

6. The method of refrigeration which comprises maintaining a desired temperature by circulating a'heat absorbing fluid in a closed circuit in which said fluid is relieved of its heat by but always separated from the same refrigerant which furnishes the operating pressure for circulating said fluid.

'7. The method of refrigeration which com-- prises maintaining a desired temperature by circulating a. secondary fluid refrigerant in a circuit in which the said fluid is relieved of itsheat by a sublimating primary refrigerant which also furnishes the operating pressure for circulating the secondary fluid refrigerant, keeping -said secondary fluid refrigerant from contact with said primary refrigerant and its sublimate, and in-.

terrupting the circulation on attaining the desired temperature.

8. A refrigeration system including in com,- bination, a closed container for a sublimating primary refrigerant, a heat releasing surface adjacent said primary refrigerant, a pump operated by gas sublimated by said primary refrigerant, a

heat absorbing surface, means for connecting said heat releasing surface, said heat absorbing surface,'and said pump in a sealed fluid circuit, and a secondary fluid refrigerant'in said sealed fluid circuit, free from any contact with the primary refrigerant or its gas.

9. A refrigeration mechanism comprising a closed container for a sublimating refrigerant, a heat absorbing coil, a pump having a piston, a heat releasing coil in said container, means for connecting both of said coils and one side of the piston of saidpump in a fluid circuit, and means for conductin .gas sublimed from a sublimating refrigerant \within said container to the other side of the piston of said pump for forcing fluid to flow through said circuit. Y

10. In refrigerating apparatus, the combination with a container having arranged therein means for holding a primary gas forming re,- frigerant, of a secondary heat exchange system associated with said container: said system comprising a coil section arranged in heat exchange relation with said holding means, a second coil section for absorbing heat from the space to be cooled, a pair of parallel pipes connected to said sections and each having arranged therein a pair of check valves, a pumping device interposed between said parallel pipes and including a pair of expansion chamber elements cooperating with said check valves to promote a circulation of secondaryheat exchange fluid through said sysmembers secured thereto and cooperating therewith to form a pair of chambers extending in -opposite directions from the control-body and each enclosing oneof said expansion chamber elements; each of said expansion chamber elements comprising a bellows secured at one end tojthe associated cap member and having its opposite end closed by a plate movable towards adjacent end of the as a bellows with one ofsaid parallel plunger and closed refrigerant to flow from a cap the adjacent bore of the and away from said control-body, a spring arranged within said bellows and resiliently urging the plate towards said body, a piston rod projecting from said plate towards said controlbody and means connecting the interior of said p pe at a point between the check valves therein; said controlbody having a flrst pair, a second pair and a third pair of bores, in axial alignment and separated from each other and terminating within the interior of the control-body; each bore of the first pair slidably receiving one end of one of said piston rods; each bore of the second pair having loosely arranged therein a valve having a stem projecting therefrom, a spring for holding said valve yieldingly to its seat and means on, the valve stem for 00- operating, with the adjacent piston rod for moving asid valve from its seat; each bore of the third pairhaving a plunger slidably arranged therein and a spring interposed between the end of the bore; means arranged within said valve body and forming a shuttle valve cylinder and having a shuttle valve slidable therein; a set of passages within the control body connecting each end of the shuttle valve cylinder through one bore of the third pair with the interior of one of the cap members, and connecting the adjacent bore of the second pair with the adjacent bore of the third mentioned pair, the-bores and passages being arranged to cause vapor evolved from the primary member through the second pair, after the from its seat, and into third pair and depress tne plunger therein against the resistance of the associated spring and then permit vapor to flow from the interior of such cap member into the said shuttle valve cylinder the associated bore of valve therein, is retracted and shift the shuttle valve tending through said valve body and connecting said thermostatically controlled conduit with said shuttle valve cylinder; and an additional set of passages cooperating with the shuttle valve cylinder and the shuttle valve for conducting refrlgerant vapor from said shuttle valve cylinder into one cap member to depress the bellows therein and for simultaneously exhausting the space within the other cap member to the atmosp ere. 11. In a refrigerating system, in combine on, a closed container for the reception of a refrigerant of the type which evaporates from a solid to a gaseous state, a compartment to be cooled, a closed conduit circuit extending into said container and into said compartment for circulating a liquid in successive heat exchanging relation with the solid refrigerant in said container and with the compartment to be cooled, a mechanical pump in said closed conduit circuit for positively circulating the liquid therein, drivthe bores of each pair being therein; a bore exmes es I Y r 5 ing mean; operated'by the pressure of the gas evolved by the evaporation of said refrigerant in said container for driving said pump without contact between the gas and the liquid, and means controlled by the temperature in the compartment to be cooled for governing the supply of gas from said container to said driving means. 12. In a refrigerating system a closed container for the reception 01' solid CO1, a chamber to be cooled, a closed conduit circuit iorcirculating a 10 liquid refrigerant in successive heat exchanging relation with the CO: in said container but without contact between the CO: or its sublimated gas and with the chamber to be cooled, means in said closed conduit circuit for positive circulation or said liquid therein, said means being driven bypressure developed through sublimation 01' saidCOz and conduit means for conveyin: gas pressure from. said closed container to said positive circulating means.

R. A. ISENBERG.

RICHARD 'S. PERSHING.

CLARENCE VAN HOUDEN KING, JR. EDWARD D. PA'I'I'ON.

ROBERT CARAWAY.

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