US2656687A

US2656687A - Apparatus for and the method of control and utilization of dry ice

Info

Publication number: US2656687A
Application number: US113811A
Authority: US
Inventors: James G Scott
Original assignee: Individual
Current assignee: Individual
Priority date: 1949-09-02
Filing date: 1949-09-02
Publication date: 1953-10-27
Anticipated expiration: 1970-10-27

Description

Oct. 27, 1953 J. G. SCOTT 2,656,687

' APPARATUS FOR AND THE METHOD OF CONTROL AND UTILIZATION OF DRY ICE Filed Sept. 2, 1949 s Sheets-Sheet 1 mod Ting-.1 4' 6 27-;-

ATTORNEY Oct. 27, 1953 J. G. SCOTT 2,656,637

APPARATUS FOR AND THE METHOD OF CONTRQL AND UTILIZATION OF DRY ICE Filed Sept. 2, 1949 I 3 sheets-sheet z v l F y INvENTOk IE ca- Jhnzs 6! A'corr ATTORNEY Oct. 27, 1953 J. G. SCOTT APPARATUS FOR AND THE METHOD OF CONTROL AND UTILIZATION OF DRY ICE 3 Sheets-Sheet 5 Filed Sept. 2, 1949 ATTORNEY Patented Oct. 27, 1953 UNITED STATES PATENT OFFICE APPARATUS FOR AND THE METHOD OF CONTROL AND UTILIZATION OF DRY ICE James G. Scott, Washington, D. 0.

Application September 2, 1949, Serial No. 113,811

4 Claims.

' erant as now ordinarily commercially supplied in blocks or cakes,

The primary purpose of this invention is to provide a refrigeration cycle particularly adaptable to use and accomplishment with apparatus for and the method of control and utilization of Dry Ice or solidified carbon dioxide.

An object is to provide apparatus and a method for utilization and control of temperatures as attained by sublimation of a block or cake of solidified carbon dioxide, to attain and restrain and maintain desired refrigerating temperatures within usable ranges, in a storage case or other refrigerating apparatus or appliance.

Another object is to provide apparatus to receive and efiiciently employ solidified carbon dioxide as a refrigerant, which apparatus employs the gas of sublimation to refrigerate and to aid in insulation and in warding off and preventing heat infiltration into a refrigerated compartment or space.

Another purpose is to provide apparatus which A will efficiently employ a block of solidified carbon dioxide to attain and maintain a desired and predetermined temperature, within usable commercial ranges, with the sublimation controlled to] expenditure of the energy of the solidified carbon dioxide only as required, without the necessity of venting offor wasting the usually excess energy of a block of material as ordinarily employed.

Still another purpose is to provide a method ;whereby a block of solidified carbon dioxide can be employed to give a desired predetermined temperature within commercially usable range, within a compartment to be refrigerated, and to I maintain'a substantially uniform and constant temperature within the compartment throughout substantially the entire life or existence of any substantial portion of the block of solidified carbon dioxide or refrigerant. Yet another object is to provideapparatus and a method whereby a substantially uniform governed temperature and a predetermined definite time or length of refrigeration can be attained and maintained efficiently and economically, and

- without waste or creation of excessively low temperatures, by the use of solidified carbon dioxide.

- Another purpose is-to provide apparatus in which solidified carbon dioxide may be employed 2 as a refrigerant, which apparatus will give desired regulated temperature within a refrigerated or storage space or compartment and will assure and will maintain a circulation of air Within the compartment.

A further object is to provide apparatus and a method capable of embodiment and use in refrigerating apparatus, such as a pie case employed for transportation of pies or for counter display and dispensing of such pies, which will give a desired temperature to preserve the pics in oven-fresh condition, and which in fact will serve to temper or condition the pies so that the crust will not become soft or soggy but will retain its original fiakiness and condition, the apparatus and the utilization of the solidified carbon dioxide being such that the pies are tempered and are preserved, and usually perishable meringues and whipped cream and other toppings will be maintained against dehydration and loss of color and loss of texture and other deteriorating effects heretofore resultant from the handling or storage of pies in usual containers, whether refrigerated or not.

Still another purpose is to provide an apparatus for use in handling and storing pies, which has supporting rack structure assuring carrying and storage of a number of pies, and which has parts adaptable for adjustment to accommodate various sizes of pies, as for example 8-inch pies, 9-inch pies, and pies of 10-inch diameter, or

larger or smaller.

of the compartment but in the refrigerating and insulated wall thereof to thus refrigerateand at thesame time to exclude and carry off heat of infiltration that would otherwise be encountered through the walls of the compartment.

Yet another, object is to provide apparatus and a method with which the Dry Ice is in a closed compartment and gas of sublimation is accumulated and generates pressure to circulate the cold gas as a refrigerating medium on the outer side of a wall of the refrigeration compartment and in a path and manner to keep the wallcold to absorb heat from the compartment and at the same time to carry away heat of infiltration through the insulated wall.

With the above and other objects in view, some of which will be apparent to those skilled in the art, and others of which are inherent in the use and construction of my improved apparatus and in the carrying out of my improved method, my present invention includes certain no'vel features of construction and assembly of parts, and certain new steps in the carrying out of the method or" process; and. certaim new features in the apparatus. which will be hereinaftersetforth in connection with the drawings and then pointed out in the claims.

The invention will appear. more clearly. fromthe following detailed descriptionwhen-takeninconnection with the accompanying drawings, showing by way of example one embodiment of my invention.

In the drawings:

Figure 1 is a view in perspective showing; a.

cabinet structure, such as a pie transportation or storage and salescase, embodyingmy, invention.

Fig. 2 is avertical sectional view taken transversely through the apparatus as. illustrated in Figure 1-.

Fig. 3 is a horizontal sectional view. Fig. 4 is a partial perspective. viewshowing one: door open andwith apie rack-inplace. V

Fig; 5. is a vertical. sectional view taken. from front to. back through; the. apparatus.-

Fig; apeISIJBCtiVe viewshowingithecentrall circulating column withtherefrigerant container at the; top thereof, as embodied in a p e storage or transporting case, andwith parts. in

dotted lines to. better showrelative positionof the-parts.

Fig; 7? is a fragmentary view in'front elevation of-v one form of pie' rack- Fig. 81s a: view in top. elevation. of the. rack. as shown in Fig; 7-.

Fig; 9515 a top-plan View showing. amodified; construction; of pie rack,

Fig; 10. is a top plan view showing. another modified: construction of pie rack. v

Fig. 11 is a fragmentary front elevational view ofthe; pie rack as shownin Fig..10.

In the. presently illustrated embodiment of my invention, I. have illustrated. and disclosed; a CELSBifOI containing pies as-these aretransported or: are held for sale, or are displayed and, dispensed; In. the present instance,v I have disclosedthe cabinet.s-tructure I,.as.having two refrigerating compartments, 2 and 3,,these, c.ompartments being. closedby doors 4. and 5.. An air, circulation" stack. 6- is; proyidediintermediate the. refrigerating compartments 2, and. 3;, and" av relatively narrow refrigerant container orcomsubstantiallysealthe refrigerant container or compartment 1.- tobe gas-tight and leak-proof.

The cabinet. structure l, is substantially open onthe forwarder door; side, and theother three sides as well-1 as. the top. and bottom-are provided with outer. insulation; The refrigerating compartm'ents 21- and 3 are-defined: by. arwa-ll structure l I, of sheet meta-l or othersuitable material,

which is spaced from the insulation material [0 so that gas spaces are provided at 12 and I3, at the bottom and top of the wall structure II, and at E4 and I5 on the sides of the refrigerating compartments 2 and 3, and at IS on the back of these compartments. The gas space as thus provided is sealed or made gas-tight, and the only outlet therefrom is through a gas escape vent I1, opening from" the top gas space l3:

As shown in Fig. 2 of.the.drawings,-the refrigerant container or compartment 1 is made relatively narrow and tall, so that the sides of this refrigerant compartment are spaced inwardly from theihner sides of the air circulation stack 6, and upper air passages I8 and [9 are provided through: the upper parts of the walls of the stack 6,.at. the sides, so that these open from the refrigerating compartments 2 and 3. Lower air passages. 20 and 2| are provided through the side walls of the stack to open from the stack into the lower. parts. of refrigerating. compartments 2 and 3.. The air: circulatiomstack. 6. is entirely within the. wall structure.- l.l-,.and'- there is of course no communication from any part; of the. gas space. around this wall H, to. the interiorof. the refrigerating compartments 2 and. 3.

The refrigerant compartment. T is. tightly closed so that gasof sublimation of the solidified carbon dioxidewill not and cannot find. its way into the-refrigerating.- compartments 2. and 3. As

the refrigerant container. orcompartment I 5 has the side and end walls thereoflentirely/separated fromthe walls. of. the stack 6.}. and. consequently not. in. contactwith any part of the walls of the refrigerator orcabinet structure, there. will not be any appreciable heat exchange. between: the side and. end'walls. of'the. refrigerant container 1,. and sublimation of. the blockv of. solidified. refrigerant can be accurately gauged aridj governed and. controlled; since heat. exchange is substantially confi'ned'tov the bottomwallof the refiigerant. container. or compartment. 1;, and theblock or cakev or slab. of; carbon dioxide refrigerant. is

. out, ofcontact with all other walls offthe refrigerant. compartment or container 1..

This refrigerant compartment I is provided on its. bottom with a. heat exchange wall 22 of metal, or other material found suitable. for the purpose, and it is through this. wall, primarily,

, that the. air within. the. refrigerating, compartments 2.' and 3. iscooled and is' circulated. The side and end walls of thei refrigerantcontainer or compartment 1 are exposedin the, upper. part of the air circulating stack 6;. but, these. side and end walls are. not primarily depended upon as heat exchange walls, and'the control'an'dutilization of the Dry Iceor. solidified carbon dioxide is. accomplished primarily through the bottom heat exchange wallZZ. Dry Ice. isnow commeroially supplied in cakes of more orlessist'andard size-and. these cakes; are cut up. into slabs or thin blocks; of desired shape and size,.for

bettercommercial' utilization. In the carrying out of my invention, I. purposely make-the refrigerant container or compartment 1 tall. and

narrow so that when a slab or thin: block of Dry Ice isplaced therein,.this thinblock. will bestood on. one. edge to rest upon. the heat exchange. wall 2 2, or uponinsulating material placed therein after. the manner and for the purpose hereinafter more fully described, Thus, the Dry Ice block; or cake or thin slab has only onesurface thereof in contact withthe refrigerant compartment, and that is the lower; thin edge face i which is in contact with or proximity to theyheat ant compartment.

heat exchange fins.

exchange wall 22 in the bottom of the refriger- Downwardly inclined air deflecting vanes 23 and 24' extend from the inner sides of the side walls of the air circulation stack 6, below the refrigerant compartment I, so that air taken in through the upper air passages l8 and I9 and then cooled by contact with the heat exchange wall 22 will be deflected and directed to the middle of the air circulation stack 6 and will then drop and flow downwardlywithin this stack to circulate into the lower part of the refrigerating compartments 2 and 3, through the lower air passages 20 and 2|. These

air deflecting vanes

23 and 24 will cause the air to sweep across the under side of the heat exchange wall 22, and the absorption of heat through thiswall will cause the cold air to then drop downwardly along the inclined

air deflecting vanes

23 and 24, and to circulate after the mannershown by the arrows.

n the lower side of the heat exchange wall 22, I provide a plurality of heat exchange fins 25, which extend transversely across and depend from the heat exchange wall 22, so that these heat exchange fins are directly in the path of flow of the circulated air as this is directed inwardly by the

air deflectin vanes

23 and 24. While I have stated that a plurality of these heat exchange fins 25 will be provided, the size or width of these fins and the number of fins can be varied to increase and decrease the heat exchange surfaces and areas as thus presented, and in this way the temperature of the circulated air can be controlled and can be varied. For example, to accomplish a lower temperature the heat exchange fins 25 can be made wider, or of heavier metal or other suitable material,

and a greater number of thesefins can be employed, thus increasing the heat exchange surfaces as presented in the path of flow of the circulated air. The heat exchange fins are associated with the heat exchange wall 22 in such manner that a direct heat exchange effect is accomplished, and as stated, the temperature to be accomplished within the refrigerating compartments 2 and 3, by circulation of air therein, can be varied and can be accurately controlled by variations in the size and number of the erant compartment has a thin lower edge, of predetermined and constant size, resting upon or adjacent to the heat exchange wall 22.

As has been stated, the refrigerantcompartment I is closed or sealed so that the gas of sublimation will not escape into the refrigerating compartments 2 and 3, or into the air circulating through the stack 6, andsince it is desired that this gas of sublimation be supplied direct to the gas spaces at the bottom, I provide a gas conducting or escape tube 26 from the compartment 1 extending down and opening into the bottom gas space 12. This gas escape or conducting tube 26 has its inlet end opening from the refrigergas escape or conducting tube 26 to flow into the This is possible because the thin block or slab of Dry Ice within the refrig-.

as space [2 at the bottom of the apparatus. As the quantity of gas increases the spacewithin the sides, at M and. I5, and the gas spacein the back, at l6, and the gas space at the top, at I3, will be filled with the carbon dioxide gas. The gas escape vent I1 is placed near the top so that there will be no escape of gas until all gas spaces are filled, and the vent will then function only to permit escape of such gas as may not be required for efiicient insulation and maintenance of the gas charge within the gas spaces.

With this construction and arrangement and functioning of the parts, the block or slab of solidified carbon dioxide can be made with the face thereof resting upon or in proximity to the heat exchange wall 22, of a predetermined size which will give a measured and governed sublimation and consequently will permit measured and accurate control of temperatures. Also, since heat absorption has been found to occur primarily from this lower face of the solidified carbon dioxide, it is possible to measure and calculate the useful life of a charge of solidified carbon dioxide by making the slab or block of refrigerant of a desired and predetermined heighth. In this way, the useful life and refrigcratingperiod of a charge of solidified carbon dioxide can be controlled and can be determined.

With the construction and functioningof the parts, in the manner set forth, the gas of sublimation will first fill the refrigerant container or compartment 1. thus giving a surround atmosphere of the inert gas, and as the gas of sublimation increases within this compartment 1, the gas will then flow downwardly through the gas conducting or escape tube 26 and will fill the entire space around the walls of the refrigerating compartment. By experiments and tests, I have found that an atmosphere of carbon dioxide gas confined between walls is a much more eflicient insulator than dead air or any commercial insulation, and that the confined carbon dioxide gas is perhaps second only to a vacuum or exhausted space, in refrigerating efliciency. Further, I have found that where the carbon dioxide gas is conducted and is confined in the manner set forth, refrigerant of the compartment is accomplished through the walls, and there is an appreciable hold-over refrigeration temperature when the block of solidified carbon dioxide is substantially reduced in size or exhausted. I have accomplished very efficient results by employment of two inches of outside insulation, and the irisulating effect resulting from confining the carbon dioxide gas in a one-inch wall space opening, but it will be appreciated that these dimensions can be varied to suit the different requirements of use. i

It has been found that the gas of sublimation leaving the block of Dry Iceor solidified carbon dioxide is only substantially 10 degrees warmer than thetemperature of the block, it being known that the temperature of Dry Ice is degrees below zero, Fahrenheit; As the gas of sublimation is substantially heavier than air, being ap proximately one and one-half times the weight of air, there is a natural tendency for the gas of sublimation to accumulate within the refrigerant compartment or'container, and within the open wall space around the refrigerating compartment; but, it must be taken into account that through circulation of air within the refrigeratin compartment and over the heat exchange wall 22, sublimation of the Dry Ice within the closed and sealed refrigerant compartment 1 is continuing.

continued sublimation accumulates gas within the-closed and .sealedicompartment l, and

theniorcesitheggas-through the tube =26 down into theabottomspacesaround the refrigerating compartments, and upwardly between the side walls.

frigerating compartment, and this circulating cold gas willaid in. refrigeration and in stabilizing. temperatures because, the side wallsof the refrigerating compartments are in effect cold heatiexchange walls. At the same time, the cold gas-"forcedupwardly within the hollow-wall will intercept and will'carry on any heat of infiltrationzthat might otherwise reach the refrigerating compartment through the side walls of the cabinet; structure.

By experiments and tests, I have determined that where the gasof sublimation leaving the block of Dry Ice mayhave a temperature of around 100 degrees below zero, Fahrenheit, I can employ this cold gas as a refrigerant and an insulating medium,- and can discharge the gas through the outlet at a. temperature substantially only 15 degrees cooler than the atmospheric temperature. These-tests indicate greatefficiency in the control of temperatures and in the utilization of Dry Ice.

With this" arrangementoif parts, heat exchange is accomplished =from the-lower: or-bottorn thin edge of the thin'block or slab: of solidified carbon dioxide resting upon or in. proximity to heat exchange wall Z2, and the gas, of sublimation will settle-within the refrigerant compartment 1 onall sides around the thin cake or slab of-Dry Ice, to serve as an insulating blanket to minimize sublimation of the Dry Ice on' any except the lower edge, the gas also serving to prevent infiltration of heat through the side walls of the refrigerant compartment 1'. limation fills the compartment, this gas will drop or flow" by its-natural weight throughthe gas escape or conducting tube 2%, to fill; gas-space l2, and as the sublimation continues all of the gas spaces will be filled and an insulating blanket of carbon dioxide gas will be establishedand maintained around the refrigerating compartments 2 and 3. It has been found that the inert gasresultant from sublimation of solidified carbon dioxide is-a very efficient insulator when used in this manner, and also experiments have shown that with this blanket or surrounding atmosphere of carbon dioxide gas, heat that would otherwise infiltrate through the insulation material I is taken up by the gas and the expanding gas carries off this heat through gas escape vent H..-

The doors 4 and 5 will of course be insulated, sothat loss of efficiency is guarded against at the access side of the refrigerating compartment.

Temperature changes and. variations can be accomplished within the refrigerating compartments fiend 3, by using a thicker or thinner slab or block of, solidified carbon dioxide, as in this wa-y the relative. area of the lower side of the As the gas of subblock. or cake: of. refrigerant asi exposed: adj acent to the heat exchange wall 2:25: can varied. However, Ii have: also found that: temperatures can be variediand-controllediwithindesiredlimits by placin'ga sheet of: paper or cardboard or-z'other heat;exchanger-insulation; as at 21; between. the upper sideaof the heat exchange Wall 22,-.and'gthe lower: side-ofthe block or cake of solidified} carbon dioxide; Bycontrolling: the size or area. of the; face of; the block or cake of Dry-Ice asexposed-on' the lower side; by.-interposition=.ofr heat exchangerinsulation material, and byvariationin the number-and-size-of the heatexchange-fins 215, it-is. possible to. obtain and' maintain very accuratedegreesof temperatureas thes maybe desired in the; refrigerating; compartments; 2 and 3 and inlike manner theexpend-iture of=energy of the solidified, carbon' dioxide: can be expedited or retarded and theusefullif ofa cakeor'block of. this refrigerant can be considerablyprolonged. At the same time, there will be no extreme-temperatures and. nouseless loss or Waste-of; energy of: the solidified. carbondioxide; Furthermore, vziththeparts constructed and arranged in the manner. set forth, and operating. as described, after. the access. door of. one or the' refrigerating compartments has been opened-andthe temperature has naturally elevated dueto higher; atmospheric temperatures,-. when the doom is again closedcirculation of air. withinathe compartment will be accelerated and the temperature of the compartment will be very quickly restoredtoistability and thedegree of refrigeratingtemperature as desired;

As stated theair circulation stack 6.is placed substantially. centrally betweenthe refrigerating compartments 2.and 3, andthe, refrigerant compartment? andflthev heat exchange portions associated therewith. are substantially centered within the stack, so that .thereis. maintenanceof substantially uniformcirculation of. air and uniform temperatures within both refrigeratingcompartments 2' and 3. Also, when, onecompartment; has been opened and the, other has'not, there will be av quicker pickup: and quicker restoration of the desired. temperature within the compartment which has been opened.

As stated the presently. illustrated. apparatus offmy present invention is to primarily provide for refrigeration andcuring ortempering or conditioning, of pies and the like. and' to. this endkI provide removable. pie-supporting. racks 23 in the refrigerating compartments 2 and 3. These removable pie racks are preferably madeupv of wire or rod members of suitable material, with the uprights 29 adapted" to fit substantially-within the compartments 2 and 3 at the. corners thereof and held in spaced-apart relation. by cross-bar; portions 30., Pie shelf or supporting rods 3! are provided in outstanding relation on each' sideto receive and supporta pie tinor' plate, after the manner shown inFig. 8.

As stated, thesepie. shelf. or supportingrodsare extended outwardly. so that. they will receive the edges of pie tins or. plates, and since commercial baking practices have established-pies of-difiYerent sizes, it is desirable that the removable racks'be made indifferent sizesto accommodate different sizes or diameters of pies. Forexam'ple, with the showing in Fig. 8, the rack will'support a 0-inch pie, with-the-showingin Fig. 9, the rack is adapted for a- 9-inch pie, and withthe disclosure in Fig. 10, therack is intended for; an 8-inch pie. With the various sizes of- 1 8-inch:- and' r-inch and 10-inch pies, it will be racks, adapted for'the appreciated that the pie shelf or supporting rods 3| will be spaced apart a suitable distance for the particular diameter of the pie plate or tin to be supported or rested thereon; and, since it is desirable that the pies be presented forwardly to be readily available when the access doors 4 and are opened, it may b found advantageous to provide upright stop rods or bars 32 to limit inward movement of the smaller sizes of pies.

As shown in Figure l, the door 9 closing the door opening 8 into the refrigerant compartment 1 is entirely separate and this door will remain closed at all times when the access doors 4 and 5 of the refrigerating compartments 2 and 3 are opened or operated. A lock or latch 33 is provided on the door 9, and the doors 4 and 5 of the refrigerating compartments 2 and 3 can have looks or latches 34 and 35, of any suitable and desirable type. i

When my improved structure is employed for carrying or transporting pies, it may be found desirable to provide lifting and carrying handles 36, and it will also be appreciated that skids or rollers or casters can be placed on the bottom of the cabinet structure, if this be desired.

In th use and carrying out of my invention in the handling and refrigeration of pies, I have found that it is possible to transport and to handle and to store cream and custard and meringue pics at a temperature which guards against deterioration and spoilage and which inhibits or retards growth and development of microorganisms. Thus, it has been found possible to transport and to store and to preserve the usually perishable pies in substantially oven-fresh condition for periods of several days from the baking or oven date, something which has heretofor been considered impossible.

Additionally, experiments and actual use in employment of my improved apparatus and method show that pies thus refrigerated are maintained in substantially oven-fresh condition without deterioration in consistency or appearance of meringues and whipped cream and other toppings, without separation of the filling from the crust, and without the crust becoming soggy or losing its desirable oven-fresh flaky characteristics. Thus, it has been found that with my apparatus and method an oven-fresh pie seems to be tempered or cured or maintained in the oven-fresh condition, and without deterioration in appearance or other characteristics, for a period of several days. The reason for this tempering or curing effect is not immediately known; but, sufficient tests have been conducted to show that a result is obtained which is not attainable by placing a pie in a refrigerator or in other apparatus or appliances heretofore available.

In the broad aspect, I have in effect accomplished a new cycle of refrigerating, in which a sealed refrigerant container accumulates gas of sublimation and generates pressure to force gas downwardly through a conducting pipe and into and up between the hollow side walls around the refrigerating compartments, so that the side walls are in effect converted into heat exchange walls for rapid pick-up of refrigeration in the compartment, and that at the same time the walls are insulated against infiltration of outside or atmospheric heat. With my improved apparatus and method, circulation of air within the refrigerating compartments stimulates sublimation of the Dry Ice and accordingly increases circulation of gas, and this increased circulation of gas aids in rapid pick-up and refrig eration of the air within the refrigerating compartments.

In other words, the air to be cooled is refrigerated directly from the solidified carbon dioxide, and indirectly from the gas of sublimation generated by the direct contact; and, this dual refrigeration joined together gives an almost perfect result, with the spent gas discharged at a temperature only slightly above atmospheric temperature.

While I have herein shown and described only certain specific embodiments of my invention and have set forth only certain variations, it will be appreciated that many changes can be made in the form and construction and arrangement of the parts, and in the steps or procedures of carrying out the method or process, without departing from the spirit and scope of my invention.

I claim:

1. Refrigerating apparatus for use with solidifled carbon dioxide comprising a doublewalled cabinet structure having refrigerating compartments therein, an air circulation stack intermediate said compartments having openings in the upper and lower parts thereof through which air in the compartment is circulated through said stack, a closed refrigerant container in the upper part of the air circulation stack and having a bottom heat exchange wall exposed therein, a gas conducting tube from the upper part of the refrigerant container discharging gas of sublimation between the double walls at the bottom of the cabinet structure, and a gas escape vent from the double wall opening at the top.

2. Refrigerating apparatus for use with solidifled carbon dioxide comprising a double cooling cabinet structure having a food refrigerating compartment therein, an upright air circulation stack having openings in the upper and lower parts through which air in the refrigerating compartment is circulated through said stack, a closed refrigerant is circulated through said stack, a closed refrigerant container in the upper part of the air circulation stack and having a bottom heat exchange wall exposed therein, a gas conducting tube from the upper part of the refrigerant container leading to discharge gas of sublimation between the double walls at the bottom of the cabinet structure, and a gas escape vent from the double walls near the top thereof.

3. Refrigerating apparatus for use with a flat rectangular block of solidified carbon dioxide comprising a double-walled cabinet structure having a refrigerating compartment therein, an upright air circulation stack within the compartment to be refrigerated having openings in the upper and lower parts through which air in the compartment is circulated through said, stack, a flat closed refrigerant container disposed in upright relation in the upper part of the stack for the fiat block of refrigerant having a bottom heat exchange wall exposed to circulation of air within the stack to have the fiat block of refrigerant placed with a narrow edge thereof adjacent to the bottom heat exchange wall, a. sheet of insulating sublimation retarding material interposed between the heat exchange wall and the block of refrigerant, a gas conducting tube from the upper part of the refrigerant container discharging gas of sublimation between the double walls at the bottom of the cabaesaesv 1'1 inetstructure, anda gas escape vent from the double wall space openingat the top.

4. Refrigerating apparatus for use with-solidifiedcarbon dioxide comprising an upright; double wall refrigerating space, an upright air circu1ationstack within said refrigerating space having openings in the upper and lower parts thereof through which air in the refrigeratingspace is circulated, a closed refrigerant container within the upper part of the circulation stack closed off from said refrigerating space and .from the space between .the double walls and provided with a heat exchange bottomwall exposed within the circulation stack, a gas conducting tube having an open upper end in the upper part of the .closed refrigerantcontainer and having a lower discharge end opening to the lower part ofthedouble wall structure whereby gas of sublimationwilhfill the. closed refrigerant container around a block of solidified carbon dioxide there- 12 in and will then enter the tube and :be discharged at the bottom to fill :between the double walls carrying off heat of infi1tration,; and a gas escape vent from the double wallspace opening at the top.

JAMES G. SCOTT.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,887,687 Killeffer N0v.,15,,19,32 1,912,446 Goosmann June 6, 1933 1,965,205 Smith July ,3, 1934 2,166,283 Betz July 18, 1939 2,209,604 Lyman July 30,1940

FOREIGN PATENTS Number Country Date 552,672 Germany Jan. 10, 1931