US2310657A - Multiple temperature refrigerating apparatus - Google Patents

Description

Patented Feb. 9, 1943 APPARATUS MULTIPLE TEMPERATURE REFRIGERATING John J. Shively, New York, N. Y.

Application November 2,1938, 'Serial No. 238,310

11 Claims.

This invention pertains to multiple temperature refrigerating apparatus.

In my Patent No. 1,907,885 are set forth and claimed a method and apparatus for the operation of a plurality of coolers in conjunction with an accumulator, by which the direct control and functioning of the individual coolers are rendered substantially independent of the operation of the primary refrigerating means.

An object of the present invention is to provide an improved apparatus for controlling the refrigerating fluids within the accumulator and coolers.

A further object is to provide improvedaccumulator and cooler apparatus for carrying out the above method.

A still further object is to provide apparatus of the above type particularly adaptedto the maintenance of a plurality of temperaturezones.

Another object is to provide apparatus of the above character comprising means to maintain a plurality of independent temperatures in a single unitary structure.

Still a further object is to provide means to operate a plurality of cooling devices at different temperatures by means of a volatile refrigerant thereinwhile maintaining substantially the same vapor pressure in all said devices.

will appear during the course of the following de-" scription in connection with the accompanyingdrawing, in which s Figure 1 is-a diagrammatic vertical transverse sectional view of a three-temperature structure illustrating thecperation of the invention; Figure 2 is a vertical sectional view of an native three-temperature structure;

Figure 3 is an exterior front view of the device shownnin r -11. I

Figure 4 is-a detail view ofthe type of liquid valve and lever shown in Figure 2:

Flgure5 is a fragmental detail view illustrating the use of internal vfins or the like toincreasethe interior condensing Fi ure 6 is a diagrammatic view or a formof altertwo-temperature unit embodying a flooded primary evaporator; and

' Figure 7 is a detail view of a means of distributing liquid refrigerant in a secondary evaporator.

Referring to Figure 1, the numeral I0 generally denotes a three-temperature cooling unit having portions of coolers l2 and I3 respectively into the upper portion of the accumulator or cooler II. Liquid passages I1 and I8 lead from the bottom of section II into the upper parts ofsections l2 and 13. The cooler sections I2 and I3 are preferablyof inverted V-shape, and the passages l1 and I8 may terminate in short spouts l9 and 20 overlying the arched or sloped inner walls 2| and 22 forming the roofs of cooling compartments 23 and 24. The liquid passages I1 and I8 are controllable by valves 25- and 26 adapted to be oper-' ated by any suitable thermostatic means, illustrated herein by those of the well known type comprising elongated casings 21 and 28 containing expansible bellows members (not shown) and having thermostatic feeler" bulbs 29 and 30 connected thereto by tubes 3.! and 32. The .bulbs may be disposed in any desired location with relation, to their respective coolers. For instance, the bulb 29 is shown attached to the outer surface of cooler l2, while bulb 30 is disposed within the compartment 24.

One or more of the thermostatic bulbs may 'also be located in the atmosphere of a, refrigerator space to be cooled, as in the case of a refrigerator having two food storage spaces divided by. a par- .tition as, as illustrated by dotted and dashed lines, Figure 1.

- The accumulator I contains a body of volatile refrigerant 33, the liquid level thereof being below the openings of passages I5 and IS. A primary evaporator, illustrated by a coil 34, is disposed in the accumulator II and has inlet and outlet pipes 35 and 36 leading through the walls thereof, the joints being permanently sealed to 31'. Liquid and suction lines 38 and 39 connect the expansion valve 31 and outlet'pipe 36 with a condensing unit lllof any suitable type. A thermostatic switch 4|, adapted to control the motor surface in the accumulator; Y

42 of unit 40, has the 'usualfeeler bulb 43 disposed in heat-exchange'relation with the accumulator manner,

section II, for in'stance in a sealed tube 44 as shown.

The accumulator section II and the liquid passages I! and I8 preferably are provided with exterior insulation 45.

The operation of the device is as follows:

The condensing unit 40, operating in the usual circulates a primary refrigerant through the primary evaporator 34, thereby refrigerating the secondary refrigerant bath 33. The thermostatic control 4| is so adjusted as to maintain the temperature in the accumulator section H at the lowest temperature desired in the system; that is, a temperature substantially below those at which the coolers l2 and I3 are intended to operate.

The thermostatic valves 25 and 26 are set to open and close within temperature ranges above that of the accumulator ll, since the coolers l2 and [3 are adapted to provide zones of higher temperature. Normally, therefore, while the valves 25 and 26 are closed, the interiors of coolers l2 and I3 are maintained substantially dry due to the fact that any comparatively warm vapor from evaporation in these lower coolers rises through the open vapor passages l5 and I6,

gives up its heat to the low temperature bath 33, 'and is condensed therein.

'When the temperature of bulb 29, controlling the valve 25 of cooler l2, rises to the maximum of its set range, the valve 25 opens and allows cold liquid from the bath 33 to fall through the passage I1 and spout l9 into the interior of cooler l2.- This cold li'quid encounters and spreads over the inner surfaces of cooller l2, receives heat therefrom and is vaporized at a temperature higher than that in accumulator II. The comparatively warm vapor thus evolved passes upward through the passage l5 and is recondensed in the liquid bath 33. The evaporation in cooler l2 refrigerates the latter until its the amounts of liquid fed or "spilled into them. Their individual temperature adjustments therefore are entirely independent of each other, the only requirement being that both must operate at higher temperature than that of the accumulator or minimum. temperature section II. Similarly, except for theirhigher ranges, the temperatures of coolers I2 and I3 have no fixed relationship with that of section H, since, if the temperature of the latter is changed, the thermostatic valves 25 and 26 simply feed greater or smaller amounts of the sub-coole liquid to their coolers as required. G

The interior surfaces of the coolers l2 and I3 may be shaped in any desired manner to distribute the entering sub-cooled liquid in the most advantageous manner, those shown in Fig ure 1 having arched inner walls 2| and 22 adapted to spread the film of liquid down both sides of the cooler.

Various distributing devices such as the spreader baflie 68 shown in Figure '7 may also be used.

Obviously the coolers may be provided with thick sections or with brine pockets for storage, with exterior or interior fins, etc., according to the particular type of installation for which the device is to be used.

The valves 25 and 26 are required only to hold the smaller liquid head above them, and need not close with absolute tightness, as small leakage would have negligible effect on the operation, simply lengthening the time between major openings of the valves. The valves therefore require little power of their thermostats, which consequently for some purposes may be of comparatively simple and cheap construction.

Figures 2 and 3 illustrate a three temperature unit in which the higher temperature coolers 46 and 41 are arranged vertically below the low temperature or accumulator section 48. The accumulator, section 48, is adapted to contain a body of liquid refrigerant 4811, with a vapor space 38b above the liquid as in the case of Figure 1. The liquid valves 49 and 50 at the lower ends of liquid passages Ila and Nb, respectively,

' are controlled by bimetallic helices SI and 52 freeizer compartment [4, and that the accumulated heat of the entire combinationis removed from the bath 33 by operation of the primary evaporator 34. As the bath 33 is of substantlsll volume and therefore possesses considerable heat storage capacity, it is also evident that the operation of the lower coolers i2 and l3 takes place whether the condensing unit 40 is in operation or not, the latterbeing controlled to maintain the bath 33 always at lower temperatime than that of coolers l2 and i3. Since all coolers are in free vapor communication with the upper portion of accumulator section II, all coolers are normally at substantially the same pressure-the only difference existing at any time in their cycles being the very small rise in vapor pressure in the lower coolers which causes their warmer vapor to move u through the passages I 5 and I6. v us, the coolers i2 and i3 are operated at 5 different temperatures not by any attempt to adapted to revolve rods 53 and 54 carrying small levers 55 and 56 engaging the valves as illustrated in Figure =4. The bimetallic elements 5| and 52 are adjustably mounted at points relatively remote from the inlets for the sub-cooled liquid so that the latter does not directly influence their temperature, and the rods 53 and 54 may be madeof Bakelite or of metal having low heat transmitting coemcient such as stainless steel.

The thermostats arethus influenced principally by the heat transmission and radiation of the adjacent cooler walls. Protecting and sealing caps 51 mayv be provided over the adjustable mountings of the thermostats. As shown, the accumulator or sharp-freezer section- 48 and the second temperature cooler 46 are insulated, from each other and from the outside atmosphere by means of asuitable body of insulatin material 430, the second temperature cooler 44 is adapted to provide an intermediate temperature compartment, while the bottom cooler 41, in addition to providing a mild temperature storage compartment, is exposed to the atmosphere of the refrigerator to provide general cooling and may be provided with exterior fins 58 for this purpose. Obviously this arrangement of the middle and bottom coolers may bereversed.

and if desired both coolers 46 and 41 may be members, as shown for illustration in the construction of the primary cooling coil 59 and I sharp-freezer pocket 60, Figure 2.

To increase the interior cooling surface exposed to the vapors entering the accumulator, members such as fins 6|, Figure 5, may be employed. The members Bl, .which may either be attached to the primarycoil 62 or may simply be loosely disposed within the accumulator 63, are partly submerged in the liquid bath 64. These members, through their large surface above the liquid level, rapidly absorb heat from the vapor entering through the passage 65 and conduct it into the bath 64, by which means coninsulated or exposed, the latter arrangement is exposed to 'the atmosphere to refrigerate theevaporated from the corresponding lower cooler. The sharp-freezer or accumulator temperature continues to fall until further lowering is stopped by the thermostatic switch 4|, Figure 1, the lower cooler meanwhile being dried out or starved as previously described, and the system assumes its normal operation throughout. During the above starting period from general warm conditions, if the compressor suction were to operate preferred in most cases, as a certain amount of additional heat absorbed through them from the atmosphere serves to accelerate the upward passage of the vapors. Y

In the foregoing illustrations the primary evaporators have been shown. as employing expansion valves. Figure 6 shows diagrammatically a two temperature unit :66 in which the primary evaporator uses the flooded system controlled by a float 61.

Instead of employing the binary system .asv hitherto described, the device may be constructed v for direct primary action by the high side unit.

on the liquid bath in the accumulator. However, the binary system is preferred for several reasons, of which the principal are as follows:

The binary arrangement permits the selection of primary fluid especially adapted to efllcient heat removal at low temperatures while a sec-' ondary fluid may be selected having other char-- acteristics most suitable for its particular service;

' coolers are substantially full of liquid, their total internal volume being preferably small enough that a substantial amount of liquid also remains in the accumulator. Under these conditions, when the compressor is started, the entire cooler systemat first is refrigerated at the same time, since the liquid has free passage through all the thermostatic valves. As the general temperature falls sufllciently to operate each thermostat the latter closes its particular liquid valve, after which the continued lowering of the accumulator temperature causes the remaining liquid to be directly on the fluid .in the entire cooler unit, a heavy load would be imposed which would either require unduly large high side capacity or would require some type of automatic restricting means to prevent overload. The limited absorbing surface of the primary evaporator noted above, prevents this unduly rapid extraction of heat and thereby distributes the initial load over a longer period, allowing the use of a comparatively small and inexpensive high side unit suited to normal operation of the system.

In the preferred forms of the invention illustrated, the low side structure forms a complete, multiple temperature unit in which the secondary fluid may be permanently sealed, the unit being adapted to be connected to any suitable refrigerating machine in the same manner as an ordinary single evaporator. The device has been illustrated as operated in connection with a high side of the compression type, but it will be understood that it is also adapted to operate with absorption systems.

From the foregoing-description it will be seen that the invention provides a method of refrigerating a plurality 'of coolers which consists in 1'. Ina device of the character described, in-

combination, an accumulator casing adapted to contain'a substantial body of volatile liquid,

means including a primary evaporator in said casing in heat exchange relationship with said liquid and adapted to refrigerate said'liquid within a pre-determined temperature range, a freezing compartment in said casing, a plurality of secondary evaporators disposed at lower level than said casing, a body of insulating material between said casing and said secondary evaporators, means forming individual passages entirely within said body of insulation and adapted to admit quantities of said liquid from said body to said secondary evaporators, individual thermostatic means .operable in-accordance with ,the individual temperatures of said secondary evaporators to control said admissions, the upper limit of said pre-determined temperature range being below any of said individual temperatures, and

individual vapor conduits exterior to said insulation and in open communication from said secondary evaporators to said casing. i

2. The combination claimed in claim 1 including means to adjust said refrigerating means to vary said pre-determined range and wherein said refrigerating means.

the lower part of said easing into said evaporator; a valve adapted to control the flow of said liquid through liquid conduit, thermostatic means to control said valve in accordance with the temperature of said evaporator, and refrigerating means to maintain said body of fluid in said accumulator at a temperature lower than the temperature of said evaporator, said accumulator casing including means to conduct heat from an exterior substance directly to said body and said refrigerating means. 4

4. The combination claimed in claim 3 wherein said volatile fluid is confined entirely within said casing, evaporator and conduits, and wherein said refrigerating means. includes a primary evaporator in heat exchange relationship with said fluid in said casing; said primary evaporator havinga plurality of heat absorbing fins extending above the level of said body of fluid in said accumulator.

5. The combination claimed in claim 3 wherein said refrigerating means includes means to adjust the temperature maintained in said accumulator, wherein said valve is disposed at the delivery end of said conduit within said evaporator, and wherein said thermostatic valve control means is adjustable independently of said accumulator temperature. 6, The combination claimed in claim 3 wherein said thermostatic means is comprised in said evaporator in heat exchange relation with a wall thereof.

7. In a device of the character described, in combination, an accumulator comprising, a chamber adaptedto contain a substantial body of volatile refrigerant, means forming an insulating body engaging substantially the entire lower exterior surface of said accumulator, an evaporator comprising a second chamber below said first chamber and having an upper exteriorwall engaging said insulating body, an interior wall of saidsecond chamber comprising an upwardly arched middle portion and substantially vertical side portions. an open vapor conduit outside said insulating body and connecting the upper portions of said first and second chambers, a

liquid refrigerant conduit leading through said insulating body from the bottom of said first chamber into the top of said second chamber directly above said arched wall portion, a valve adapted to control the flow of liquid through said conduit, thermostatic means to control said valve, means to refrigerate said body of refrigerant in said accumulator, and means forming a freezing chamber within said accumulator.

8. A unitary cooling device comprising in combination, an upper tank adapted to hold a substantial body of liquid refrigerant and having a vapor space above said liquid, a second tank directly below said first tank and comprising a single chamber of inverted U-shape, an insulating body between said tanks and engaging the same, a vapor conduit outside said insulating body and leading from the upper portion of said chamber to said vapor space in said first tank, a liquid conduit from thebottom of said first tank into the top of said inverted U-shaped chamber, a valve adapted to control liquid flow through said conduit, thermostatic means to control said valve, and an evaporator in said first tank,

9. A unitary cooling device comprising in combination, anupper cooler adapted to hold a substantial body of volatile liquid refrigerant and having a vapor space above said body, a lower cooler under said upper cooler, an open vapor conduit connecting the upper portion of said lower cooler with said vapor space, a liquid conduit connecting the lower portion of said first cooler with'the top of said second cooler, a refrigerating evaporator in said first cooler, and a plurality of heat conducting member of substantial surface disposed in said first cooler and extending from below the surface of said liquid body into said vapor space. j

10. In a unitarycooling structure, in combination, an accumulator. adapted to contain a substantial body of liquid refrigerant, said accumutor into the upper portions of sai 'evaporators, valves in said evaporators at the ends of said liquid conduits, thermostatic means comprised entirely within said evaporators and adapted to control said valves, and means to refrigerate said liquid in said accumulator. 1l. Astructure as claimed in claim 10 wherein said first and second evaporators are of-inverted U-shape and including heat-absorbing fins on said second evaporator.

- JOHN J. SHIVELY.

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