US3220213A - Freezer with intermediate refrigerant means for receiving and discharging heat - Google Patents

Description

Nov. 30, 1965 H WAKEMAN T 3,220,213

FREEZER WITH INTERMEDIATE REFRIGERANT MEANS FOR RECEIVING AND DISCHARGING HEAT Filed 001;. 25, 1963 2 Sheets-Sheet 1 INVENTOR.

Nov. 30, 1965 wAKEMAN ETAL 3,220,213

FREEZER WITH INTERMEDIATE REFRIGERANT MEANS FOR RECEIVING AND DISGHARGING HEAT 2 Sheets-Sheet 2 Filed Oct. 25, 1965 .OO/ .00/5 .002 -OOZ$" .005

04 F/LM 7f4/cnuess A a/es 0e I- EM GFZ TO INVENTOR. @424 7% Wm BY ewa 8mm United States Patent FREEZER WITH INTERMEDIATE REFRIGERANT MEANS FOR RECEIVING AND DKSCHARGKNG HEAT Alden H. Wakeman, Lake Mills, Wis., and Leon Buehler, Jr., Skokie, lll., assignors, by mesne assignments, to St. Regis Paper Company, New York, N.Y., a corporation of New York Filed Oct. 25, 1963, Ser. No. 319,076 6 Claims. (Cl. 62-333) This invention relates to a refrigeration system and more particularly to a heat transfer apparatus wherein coating of one or more of the heat-transfer wall surfaces thereof by oil, scale, sediment, rust, or other contaminates, which adversely effect the heat transfer rate of such surface, is minimized and thus results in a system of high efficiency.

Heat transfer apparatus having high heat flux-that is to say, apparatus having a high overall coefficient of heat transfer and operating with a large mean temperature difference-is particularly sensitive to surface fouling. Because of high initial costs, need for miniaturization, and compatibility with associated apparatus, heat transfer apparatus of the type in question is normally equipped with a small heat transfer wall surface.

Representative of such apparatus is a continuous ice cream freezer exemplified in US. Patent No. 2,210,366 issued on August 6, 1940. In such an apparatus, ice cream mix and air are introduced at one end of an elongated cylindrically-shaped freezer chamber, pass longitudinally therethrough while undergoing a whipping action, and then the aerated mix in a partially frozen state is discharged from the opposite end thereof. The wall, defining the chamber, constitutes the heat transfer surface for the mix while passing through the cylinder. The exterior of the wall is chilled by a suitable refrigerant so as to cause a thin layer of mix to freeze on the interior surface of the wall. As the layer of mix freezes on the interior surface, it is mechanically scraped off and mixed with the remainder of the mix by a dasher assembly.

Due to normally rigid public health regulations, the various component parts comprising apparatus of this type must be carefully fabricated from high cost materials such as stainless steel and nickel. In addition, where the particular part is in direct contact with the product being processed, the part must normally have the exterior thereof rubbed to a high gloss finish for sanitary reasons. Thus, because of high material and labor costs involved, apparatus of this type requires a substantial capital investment. To provide a larger freezer chamber in order to effect greater freezing capacity would not only increase materially the initial cost, but, in addition would require in many instances heavier and more bulky component parts (e.g. a dasher assembly) which, in turn, would complicate periodic removal of such parts for cleaning, blade sharpening, and other essential purposes.

Ice cream freezers and associated equipment normally require the constant attention of a skilled operator and thus to minimize high overhead costs, the most economical operation of the equipment is earnestly sought, which demands the greatest practical hourly output from the equipment. The limiting point as to output is reached, however, when the dasher motor is loaded to the maximum; at this condition, the main temperature difference is likely to be about 40 to 50 F. (e.g. mean temperature of product and refrigerant temperature).

Due to certain inherent and unique characteristics of ice cream, for example, optimum whipping thereof and air incorporation occur when there is extremely rapid freezing so that only minut'e ice crystals will be formed in the end product and thus an extremely high heat flux is considered essential in freezers of this type. Such freezers are commonly chilled by the outer surface of the freezer cylinder being immersed in cold liquid ammonia. In prior freezer constructions, such ammonia is normally circulated throughout the system and over the freezer cylinder by means of a compressor. Because of such compressor, however, small amounts of the oil utilized for lubricating various moving parts of such compressor, b'ecome entrained in the circulated ammonia. While oil separators, and the like, are customarily used to remove the entrained oil from the refrigerant, such equipment is not completely effective and thus, some of the entrained oil becomes deposited on the outer surface of the freezer cylinder.

The thermal conductivity of a one inch thickness of oil is approximately 1 B.t.u. per hour, per square foot, per degree F. Thus, an oil film of .001" thickness would transmit 1000 B.t.u./hr. ft. deg. F. and the fouling factor (1), which is the reciprocal of the conductance, would equal 1/1000 or .001 per .001" thickness.

Freezers of the type in question, when possessed of a clean cylinder refrigerating surface, will have an approximate overall coetlicient of heat transfer (U :500 B.t.u./hr., ft. deg. F. based on the internal surface of the cylinder. Thus, the actual coeflicient of heat transfer Since it is important that the temperature of the discharged product (aerated ice cream mix) be kept constant as much as possible, it is necessary to lower the ammonia temperature so as to increase the operating mean temperature difference to compensate for the change in the coeflicient of heat transfer as the oil film thickness builds up. When the limit of temperature reduction has been reached because of limitations of the plant refrigeration system, further oil film buildup can only be compensated for by reducing the rate of ice cream production. As aforenoted, because of the high labor and material costs involved with such equipment, reduction in ice cream production increases unit production costs. Freezers ordinarily are rated at about 300 B.t.u./ hr. ft. deg. F. and at about 50 F. M.T.D. which, in turn requires ammonia to be cooled to approximately 26 F.

Theoretically providing fins (extended surface) on the outer surface of the freezer cylinder substantially increases the coefficient of heat transfer. In actual tests, it has been found that cutting a 60 thread in the outer circumference so as to double the surface area, increases the coefficient to the order of approximately 800. The effectiveness of such fins is rapidly diminished, however, because of the buildup of an oil film on the threads. The use of such fins has proved a detriment because of their interference with the draining of oil and therefore prevent great reduction of the heat transfer coefficient.

Thus, if oil or other contaminates can be prevented from reaching the heat transfer surface of the freezer cylinder, reduction of the coeflicient of heat transfer is avoided.

Thus, it is one of the objects of this inv'ention to provide a refrigeration apparatus wherein surface fouling agents have been excluded from the refrigerant and thus, the effectiveness of the heat transfer surface of the freezer cylinder remains unchanged even after prolonged use of the apparatus.

It is a further object of this invention to provide a re frigeration apparatus wherein the cooling action thereof may be quickly interrupted, when desired, without the buildup of high pressures within the system itself.

It is a further object of this invention to provide a refrigeration apparatus which utilizes a primary refrigerant source and a secondary refrigerant source and said primary source is in a sealed system requiring no mechanical actuating means to effect circulation of the refrigerant within said sealed system.

Further and additional objects will appear from the description, accompanying drawings, and appended claims.

In accordance with one embodiment of this invention, a refrigerating apparatus is provided which comprises a freezer first chamber, a primary refrigerant second chamber substantially surrounding said first chamber and separated therefrom by a first heat transfer wall surface, and a secondary refrigerant third chamber separated from said second chamber by a second heat transfer wall surface. Communicating with said second chamber is a primary refrigerant accumulator vessel into which said primary refrigerant accumulates when the apparatus is inoperative. Cooperating with and in heat exchange relation with said accumulator vessel is heating means; selectively actuated to effect transfer of the accumulated primary refrigerant from said vessel to said second chamber. The area of said second heat transfer wall surface being substantially greater than the area of said first heat transfer wall surface.

For a more complete understanding of this invention, reference should be made to the drawings wherein:

FIG. 1 is a fragmentary perspective view partially in section of the improved apparatus.

FIG. 2 is an enlarged fragmentary vertical sectional view showing the heat transfer wall surface between the primary refrigerant and secondary refrigerant chambers.

FIG. 3 is an enlarged fragmentary vertical sectional view of a modified form of improved apparatus.

FIG. 4 is a chart which shows the effect of various thicknesses of oil accumulated on a heat transfer wall surface with respect to the overall coefficient of heat transfer of said surface.

Referring now to the drawings and more particularly to FIG. 1, one form of the improved refrigeration apparatus is shown, which in this instance is an ice cream freezer adapted primarily for use in commercial dairies and the like.

The apparatus 10' includes a housing 11 having insulated exterior walls. Disposed within housing 11 is an elongated freezer cylinder 12 through which the ice cream or a similar product is caused to pass longitudinally from the rear to the front. A suitable access panel, not shown, is provided at the front of the cylinder and housing to permit the discharge of the frozen ice cream or similar product.

Disposed within the cylinder interior A and driven about the longitudinal axis thereof is an elongated dasher and heater assembly, not shown. An assembly, adapted for use in the cylinder interior, is the subject of a copending application for United States Letters Patent, Serial No. 319,078 filed October 25, 1963.

Various other types of dasher and heater assemblies may be utilized within the cylinder assembly such as is disclosed in Wakeman United States Patents 2,867,994 and 3,037,748. The dasher and heater assembly in all instances is driven from a suitable power source disposed externally of the freezer cylinder 12. The dasher and heater assembly, as the name implies, vigorously agitates the mix, at least part of the time as it is passing through the freezer cylinder and thus, produces a frozen product, such as ice cream, which is possessed of the desired overrun. In addition the assembly is provided with scraper blades which prevent the build-up of frozen mix on the interior wall surface of the freezer cylinder. The function and operation of the dasher and beater assembly is generally well known by those skilled in the art.

The cylinder 12 has the cylindrical wall thereof preferd ably formed of a suitable metallic material possessed of a high. coefiicient of heat transfer. The length and internal diameter of the cylinder 12 will vary depending upon the rated capacity of the apparatus and the type of product to be frozen.

The cylinder 12, as shown in FIG. 1, is disposed within a chamber 13, formed in part by the lower portion 11a of housing 11 which is spaced from and subtends the cylinder and a wall or partition 14 spaced above the cylinder and supported about its periphery by housing 11.

Contained within chamber 13 is a primary refrigerant B, which may be a liquid, oil free, ammonia, precooled to approximately 26 F. The primary refrigerant B should be of suflicient quantity as to cause complete, or substantially complete, submersion of cylinder 12 therein, see FIG. 1.

The partition 14, in the illustrated embodiment, includes a plate 15 formed of a suitable metal or similar material having a high coefiicient of heat transfer and provided with a plurality of symmetrically arranged, spaced openings 16, see FIG. 2. Fitted securely into each opening 16 is an elongated tubular-shaped element 17, which is likewise formed of metal or similar material having a high coefiicient of heat transfer. The hollow interior of each element 17 communicates directly with chamber 13 and, thus entraps therein vapors of the primary refrigerant B when the latter volatilizes upon absorbing the heat transmitted through the cylinder wall by the product circulating through the cylinder interior A. As the entrapped primary refrigerant vapors become condensed within the hollow tubular elements 17, in a manner to be described more fully hereinafter, the condensed vapors will fall by gravity back into chamber 13 and if cylinder 12 is not completely submerged in refrigerant B, will cause wetting of the upper portion of the cylinder wall surface.

The partition 14 serves as a liquid-tight separation between lower chamber 13 and an upper chamber 18, the latter being formed by the sides and top of housing 11. Disposed within chamber 18 is a secondary refrigerant C. Refrigerant C is adapted to absorb the heat from the entrapped vaporous primary refrigerant upon condensing thereof.

Subtending the housing 11 is an accumulator vessel 20. The vessel interior is in communication with the bottom of chamber 13 by a tube 21. The lower end of tube 21 terminates adjacent to, but spaced from the bottom of the vessel interior for a purpose to be explained more fully hereinafter. Connected to vessel 20 and communicating with the upper end of the vessel interior is one end 22a of an equalizer pipe 22. Pipe 22, in the illustrated embodiment, is disposed exteriorly of housing 11 and has the other end 22b thereof connected to upper portion of chamber 13, just beneath partition 14. Disposed within pipe 22 intermediate the ends thereof is a quick closing shutoff valve 23, the operation of which will be discussed more fully hereinafter. Sufiice to say at this time, that, when valve 23 is open, pressure within chamber 13 is equalized whereupon the liquid primary refrigerant disposed therein will flow by gravity into vessel 20. The volumetric capacity of vessel 20 should be such that all of the liquid primary refrigerant can be accumulated therein.

In the illustrated embodiment, an electrically energized heating element or probe 24 is disposed within the vessel interior. Electrical leads 25 interconnect the heating element 24 with a switch 26 for the dasher and heater assembly drive motor, not shown.

Upon the heating element becoming energized, the valve 23 in the equalizing pipe 22 is automatically closed, whereupon the volatile refrigerant accumulated within vessel 20 results in a pressure developing within the upper portion of the vessel interior, whereupon the accumulated liquid refrigerant is forced up through tube 21 into chamber 13. Other ways, besides that shown, of producing the volatilizing heat for the accumulated primary refrigerant may be utilized if desired.

Communicating with the upper portion of chamber 18 is a secondary refrigerant input conduit 27 which forms a part of the secondary refrigerant system. Also communicating with the upper portion of chamber 18 is a second conduit 30 which is adapted to permit removal of secondary refrigerant vapors which have accumulated within the upper portion of chamber 18. Conduit 30 constitutes the suction line for the secondary refrigerant system. Disposed within conduit 30 is an adjustable regulating valve 31 which is adapted to control the upstream pressure and thus, the temperature. The secondary refrigerant system also includes the customary compressor and condenser and component parts therefor, none of which is shown.

A pilot line or conduit 32 having a regulator valve 33 incorporated therein is mounted on the upper side of housing 11 and communicates with the upper portion of chamber 18. Adjustment of valve 33, which is shown to be manual, controls the operating secondary refrigerant pressure within chamber 18. While valve 33 is shown to have a manual adjustment, such, if desired, may be replaced by an automatic temperature responsive adjustment. With this latter adjustment, a sensing element, not shown, would be positioned at the discharge end of the freezer cylinder 12. An electrically operated valve 34 is also disposed within conduit 32 and is in series relation with manually adjustable valve 33. Upon shutdown of the freezer cylinder operation, valve 34 automatically closes thereby rendering valve 33 as an ineffective pressure regulator.

An additional conduit 35 is provided which communicates with the upper portion of chamber 13 and is adapted to serve as a further connection between chamber 18 and regulating valve 31. Disposed within conduit 35 is a valve 36 which serves to control the pressure within chamber 18 when it reaches a higher value and when valve 34 is not in control.

A hot gas line or conduit 37 is provided which connects the discharge line of the secondary refrigerant system with the lower portion of chamber 18. An electrically actuated valve 38 is disposed within conduit 37. The adjustment of valve 38 is determined by a defrost selector switch 40 and a second switch 41, the latter preferably being actuated by the temperature of the liquid secondary refrigerant within chamber 18, but alternately by the pressure within said chamber.

A double throw switch 42, which is actuated by the position of quick-acting shutoff valve 23 disposed within equalizer line 22, serves to close valve 34, when the freezer cylinder is shut down. Simultaneous actuation of switch 42 and valve 23 may be accomplished by an elongated rod 43 which projects from one side of the housing for valve 23. Rod 43 is rotated about its elongated axis by a hand lever 44 affixed to one end thereof. Keyed to rod 43 is a cam 45 which in turn is in continuous contact with a follower pin 46 projecting from the housing for switch 42.

When the freezer is initially placed in operation a supply of primary refrigerant is introduced into vessel 20 through a valve and pipe assembly 47 which is connected to the underside of the vessel. The primary refrigerant is preferably pure oil-free ammonia. Normally the source of pure ammonia is a drum or the like, not shown, which because its location during storage might have picked up some heat so that a substantial part of the ammonia will have vaporized and thus be under a presssure of approximately 150 p.s.i.g. Within a short period of time (e.g. one half hour) the pressure within vessel, chamber 13, and the drum will have equalized and substantially complete diffusion of the ammonia vapors and the air within the vessel and chamber will have occurred. The pressure within the chamber and Cit vessel is then substantially blown off leaving only a slight pressure remaining therein so as to prevent the introduction of outside air. Additional pure ammonia vapors are again introduced into vessel Zil and chamber 13 through assembly 47, and the foregoing procedure repeated until virtually no non-condensable gas remains in either the vessel or chamber. If desired, instead of blowing down, a high vacuum may be pulled on the chamber and vessel before the pure ammonia vapors are admitted. After the non-condensable gases have been expelled from chamber 13, the latter is charged with the proper amount of pure liquid ammonia, while chamber 18 is being refrigerated with the secondary refrigerant C.

When the operator wants to interrupt refrigeration, he manually turns lever 44 so as to open valve 23 causing pressure within chamber 13 to be equalized whereupon the liquid pure ammonia disposed within the chamber is quickly drained through tube 21 into vessel 21 Simultaneously with the opening of valve 23, switch 42 is actuated which, in turn, causes pressure regulator valve 31 to close. Because of the fact some condensation of the vapors entrapped in tubes 17 will continue after shutdown, boiling or volatilizing of the secondary refrigerant C within chamber 18 will continue to occur and thus gradually increase the pressure within chamber 18. When the pressure within chamber 18 has reached a predetermined amount, established by the setting of valve 36, valve 31 will then open a sufficient amount so that the temperature within chamber 18 will he considerably above 32" F. at the boiling point of the refrigerant at the increased pressure.

If more rapid temperature buildup within chamber 18 is desired, the operator may actuate defrost selector switch 40, which, in turn, opens valve 38 thereby permitting hot gas to be admitted into chamber 18. When the temperature of the liquid secondary refrigerant C (or pressure within chamber 18) reaches the predetermined setting of switch 41, valve 38 automatically closes shut-ting off further introduction of the hot gas into chamber 18. If desired, switch 40 may be left closed at all times in which case the opening of valve 23 by hand lever 44, will automatically open valve 38. Whenever the dasher and beater assembly, not shown, which is disposed within freezer chamber A, is stopped, heater probe 24 will automatically become de-energized and the valve 38 for the .hot gas closed.

Tubes 17, as aforementioned, are preferably made from a relatively inexpensive metallic material as compared to the freezer structure as a whole, and, thus, a greatly increased freezing capacity can be economically produced because of the very large heat transfer wall surface attained by the combined effect of the plurality of tubes.

Suppose, for example, that 22 /2 times more tube surface is obtained as compared to the interior wall surface of freezer cylinder 13 and that such surfaces are not contaminated by an oil film or the like, then the coefficient of heat transfer for the tubes according to chart, FIG. 4, would be approximately 500 as compared to 800 for the freezer cylinder. The figure of 800 for the freezer cylinder is due to the heat exchange surface thereof being extended by reason of fins or the like being formed on the exterior thereof. As aforenoted, however, in the conventional freezer, the exterior surface of the freezer cylinder cannot be finned because of the fouling factor which occurs when an impure refrigerant is used. The overall coefficient of heat transfer (U) would then be tubes. If an oil film of .0001" thickness would accumulate on the tube surface, then the coefiicient of heat transfer thereof according to the chart of FIG. 4 would equal approximately 470, whereupon the overall coefficient of heat transfer (U) for the apparatus would be In the conventional freezer, however, with the same oil film, the coefficient of heat transfer would be 470. The volume of oil which would coat the tubes with an .001 thickness film, would, on the other hand, coat the freezer cylinder surface with a film 22 /2 x .0001=.00225", the tubes 17 were omitted, whereupon the coefficient of heat transfer would drop to 240, see chart, FIG. 4.

Let it be assumed that, after a predetermined period of operation, that the oil film accumulation on the tubes 17 reaches a thickness of .0005". According to the chart, FIG. 4, the coetficient of heat transfer will then be 400 and the overall It is apparent from the aforenoted illustrations, that the U for the conventional freezer falls off much more rapidly than with the improved freezer aforedescribed.

In FIG. 3, a modified form 50 of the invention is shown, which includes a product cooling cylinder 57 formed from a suitable material having a high coefficient of heat transfer. The cylinder 51 extends through an enclosure 52 in which is disposed the primary refrigerant D, which is in pure form (that is to sayoil free). The oil-free primary refrigerant D is introduced into the enclosure 52 through a suitable valve and pipe assembly 52; communicating with the underside of the enclosure. The device 50 may be operated to cool a product flowing through cylinder 51 at a temperature level considerably higher than what is ordinarily considered refrigeration. Thus, it should be understood that the term primary refrigerant is intended to include a cooling medium (e.g. water) which boils by absorbing heat from the product in cylinder 51.

Disposed above cylinder 51 and in substantially parallel relation with respect thereto are a plurality of tubes 53. Distributing heads or manifolds 54 and 55 are removably mounted on enclosure 52 adjacent the corresponding open ends of tubes 53. Head 54 is provided with a pair of spaced internally threaded ports 54a and 54b. to which suitable connections to a source of secondary refrigerant or coolant, not shown, may be made. Disposed intermediate the ports is a projection or partition 540, which is adapted to engage a wall surface of enclosure 52, and thus prevent a secondary refrigerant or cooling medium from passing through one port and out through the other, except through the tubes 53 in the direction as shown by the arrows in FIG. 3. The secondary refrigerant may, in certain instances, constitute cooling water.

The heat absorbed by the primary refrigerant from the product flowing through cylinder 51 causes vaporizing of :at least a portion of the primary refrigerant which, in turn, collects in the upper interior portion of enclosure :52. The collected primary refrigerant vapors are then condensed by the coolant circulating through tubes 53 :and the condensed primary refrigerant falls by gravity into the lower portion of the enclosure. Suitable controls, not shown, may be utilized to control the temperature of the primary refrigerant and the pressure within the enclosure interior.

Any scale or other foreign material which may become deposited on the interior surfaces of tubes 53, may be reamed out or otherwise removed, when required, by removing heads 54 and 55. As in the case of apparatus 10, the combined surface area of tubes 53 is substantially greater than the heat transfer surface of cylinder 51 disposed within enclosure 52. The scale or foreign deposits within the interiors of the tubes 53, effects the co efficient of heat transfer thereof in substantially the same way as the oil film, heretofore discusssed.

Thus, it will be seen that a refrigerating apparatus has been provided wherein the heat transfer efiiciency thereof remains substantially uniform even after prolonged use of the apparatus. Furthermore, the freezing cycle for the improved apparatus may be readily interrupted without danger to the various components of the apparatus or the personnel operating such apparatus.

While several embodiments of this invention have been described above, further modifications may be made thereto and it is contemplated, therefore, by the appended claims, to cover any such modifications as fall within the true spirit and scope of this invention.

We claim:

1. A refrigerating apparatus comprising a product first chamber disposed in the lower portion of an encompassing second chamber, said first chamber being formed by a first heat-transfer wall; a captive charge of a primary volatile refrigerant disposed within said second chamber and normally in liquid phase to a sutficient depth to substantially immerse and wet the exterior surface of said first wall; the upper portion of said second chamber including a plurality of elongated upright pockets, each having an open lower end, the interior of each pocket being in direct communication with the upper portion of said second chamber through said open lower end; a third chamber separated from and in heat transfer relation with the upper portion of said second chamber; and a secondary volatile refrigerant disposed within said third chamber and substantially wetting the exterior of each pocket whereby said primary refrigerant vapor disposed within said pockets is liquefied and returned by gravity to the liquid primary refrigerant accumulated in said second chamber.

2. The apparatus recited in claim 1 including an accumulator vessel communicating with said second chamher, said vessel having a volumetric capacity for accommodating all of the liquid phase of said primary refrigerant, and control means communicating with said second chamber and said vessel for effecting at predetermined times transfer of all of said primary refrigerant between said second chamber and said vessel.

3. The apparatus recited in claim 2, wherein said vessel subtends said second chamber.

4. The apparatus recited in claim 3 wherein said control means includes a first conduit connecting the bottom of said second chamber with the bottom of said vessel, a second conduit connecting the said upper portion of said second chamber and the upper portion of said vessel; an adjustable valve means cooperating with said second conduit and, when in a first open position of adjustment, effecting flow of said liquid primary refrigerant through said first conduit from said second chamber to said vessel; heating means cooperating with said vesssel for effecting vaporization of the primary refrigerant accumulated in said vessel and for effecting reversal of primary refrigerant fiow through said first conduit only when said valve means is in a second closed position of adjustment.

5. The apparatus recited in claim 3 including means for heating said first chamber when the cooling cycle for said apparatus has been interrupted, said means comprising a heater associated with said vessel and selectively operative for raising the temperature of the liquid primary refrigerant accumulated within said vesssel whereby refrigerant vapors become entrapped within the upper portion of said vesssel, and conduit means interconnecting said second chamber and said vessel whereby at predetermined intervals said refrigerant vapors will be transferred from said vessel to said second chamber and condensed on the surface of said first chamber.

6. The apparatus recited in claim 5 including means for simultaneously raising the temperatures of said sec- 9 10 ondary refrigerant and the primary refrigerant when the 2,970,811 2/1961 Ruch et a1 165105 latter is accumulated in said vessel. 2,986,903 6/ 1961 Koeher et a1 62-333 FOREIGN PATENTS References Cited by the Examiner 28 586 12/1932 Netherlands UNITED STATES PATENTS 5 5 472 7 1953 Narbut 1 5 1 4 MEYER PERLIN, Prlmary Exammer- 2,924,635 2/ 1960 Narbut 165105 ROBERT A. OLEARY, Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,220,215 November 50, 1965 Alden H. Wakeman et 211.

It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 7, line 12, for ".001" read .0001--; line 14, before "the" insert if same column 7, line 37, for "52" read 52 column 8, line 50, for "vessel," read vessel;

Signed and sealed this 11th day of October 1966.

(SEAL) Attest:

ERNEST W. SWIDER Attesting Officer EDWARD J. BRENNER Commissioner of Patents

Claims (1)

1. A REFRIGERATING APPARATUS COMPRISING A PRODUCT FIRST CHAMBER DISPOSED IN THE LOWER PORTION OF AN ENCOMPASSING SECOND CHAMBER, SAID FIRST CHAMBER BEING FORMED BY A FIRST HEAT-TRANSFER WALL; A CAPTIVE CHARGE OF A PRIMARY VOLATILE REFRIGERANT DISPOSED WITHIN SAID SECOND CHAMBER AND NORMALLY IN LIQUID PHASE TO A SUFFICIENT DEPTH TO SUBSTANTIALLY IMMERSE AND WET THE EXTERIOR SURFACE OF SAID FIRST WALL; THE UPPER PORTION OF SAID SECOND CHAMBER INCLUDING A PLURALITY OF ELONGATED UPRIGHT POCKETS, EACH HAVING AN OPEN LOWER END, THE INTERIOR OF EACH POCKET BEING IN DIRECT COMMUNICATION WITH THE UPPER PORTION OF SAID SECOND CHAMBER THROUGH SAID OPEN LOWER END; A THIRD CHAMBER SEPARATED FROM AND IN HEAT TRANSFER RELATION WITH THE UPPER PORTION OF SAID SECOND CHAMBER; AND A SECONDARY VOLATILE REFRIGERANT DISPOSED WITHIN SAID THIRD CHAMBER AND SUBSTANTIALLY WETTING THE EXTERIOR OF EACH POCKET WHEREBY SAID PRIMARY REFRIGERANT VAPOR DISPOSED WITHIN SAID POCKETS IS LIQUEFIED AND RETURNED BY GRAVITY TO THE LIQUID PRIMARY REFRIGERANT ACCUMULATED IN SAID SECOND CHAMBER.

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