US2337600A - Method and apparatus for refrigerating transportation enclosures - Google Patents

Description

-Dec. 28, 1943. A, HARRIS 2,337,600

METHOD AND APPARATUS FOR REFRIGERATING TRANSPORTATION ENCLOSURES Filed Nov. 8, 19,40 2 Sheets-Sheet l 'D.28, 1943. A, RRlS 2,337,600

METHOD AND APPARATUS FOR REFRIGERATING TRANSPORTATION ENCLOSURES Filed Nov. 8, 1940 2 Sheets-Sheet'Z gwuwwboc no attempt is made Patented Dec. 28, 1943' UNITED STATES PATENT OFFICE METHOD AND APPARATUS FOR. REFRIGER- ATING TRANSPORTATION ENCLOSURES Allyn Harris, Wheaton, 111., assignor, by mesne onstruction Finance Corassignments, to Rec poration, Chicago, 111.,

United States a corporation of the Application November 8, 1940, Serial No. 364,945.

19 Claims.

'after they are loaded and, if the transportation time is sufficiently long, the bodies are re-icede'n route. While these bodies are standing empty,-

either awaiting transportation to loading points or awaiting loads at said points, and while they are actually being returned to the loading points, to control the temperature prevailing in the interiors of the body. Consequently, the temperatures oftentimes reach such high values that 24 to 48 hours of normal icing time is required before the interiors of the bodies can be lowered to a commodity preserving temperature. A e

' they are spotted at the loading If refrigeration is obtained by employing ice A bunkers at the ends of the car or truck bodies, it is possible to precool the bodies before they are loaded 50 that the perishable commodities are not subjected to this high temperature, Of course, during such precooling periods the equipment is lost to both the owners and the shippers.

If only crushed or snow ice is to be used to top ice the commodities, loading must be accomplished before this refrigerating medium may be applied. Therefore, it is necessary to subject the perishable produce, which is warm to start with, to the overheated temperature of the enclosure during loading and to the gradual lowering of the temperature during the initial cooling period.

Attempts have been made to shorten the precooling period, where ice bunkers are employed,

by first delivering to the bunkers a refrigerating medium which has a much higher rate of heat absorption than has water-ice. After the desired low temperature hasbeen obtained with this spe- 1 cial refrigerant, the usual charges of water-ice,

in block form, are substituted in the bunkers for the special refrigerant. This type of procedure does reduce the time lost to a certain extent, but several hours still are needed because natural air circulation past the bunkers and throughout the load carrying enclosure is relied upon to accomplish the desired lowering of the temperature. Furthermore, the loading costs are increased to a considerable extent as a result of the necessity of handling these two refrigerants.

Another procedure which has been proposed i's'to create a forced circulation of air through the enclosure after the boxes and crates of warm produce have been loaded. The principal purthe first one of the series.

during the loading a preservin during transportation.

I of crushed or snow ice employedinitially in It is the primary purpose of this invention toprovide methods and apparatus for effectively" precooling the interiors of transportation vehicles, employed for shipping refrigerated perishable commodities, without depriving the owners or shippers of the use of the vehicles for more than a very few minutes at the most In fact, the loading of a series of vehicles may be carried out in quick succession, starting as soon as platform, and the need only apply to The time required to load the first will be ample to allow for precooling several of the succeeding bodies.

A further important object of the invention is to provide methods and apparatus for effecting precooling of refrigerator vehicles before placing loads of perishable commodities therein and for effecting initial refrigeration of the commodities period.

Still another object of the invention is to provide methods and apparatus for precooling refrigerator vehicles before loading, effecting initial refrigeration of the perishable commodities during loading, and refrigerating the commodities in bacteria-destroying atmosphere loss of time for precooling Another object of the invention is to provide methods and apparatus for reducing theamount top icing perishable commodities transported in refrigerator vehicles and eliminating the need for re-icing en route.

Other objects and advantages of the invention will be apparent during the course of the following description.

In the accompanying drawings forming a part of this specification and in which like numerals are employed to designate like parts throughout the same,

Figure 1 is a schematic view, partly in vertical section and partly in side elevation of a railway refrigerator car and the apparatus required to carry out the precooling method embodying this invention,

Figure 2 is a side elevational view of a railway refrigerator car modified to adapt it for being refrigerated by the method embodying this invention,

Figure 3 is a vertical sectional view taken through the refrigerator car disclosed in Fig. 2 and illustrates a method of refrigerating commodities transported in railway cars, or the like, by means of water-ice and a refrigerating fluid, Figure 4 is a horizontal sectional view.of a refrigerator car permanently equipped with apparatus for accomplishing precooling and refrigerating en route,

Figure 5 is a detail, vertical sectional view illustrating the use of the permanently installed equipment of Fig. 4 for accomplishing refrigeration en route, and

Figure 6 is a fragmentary, detail, vertical sectional View of a modified form of. permanent precooling and refrigerating equipment-for a transportation body.

In the drawings,-.wherein for the purpose of illustration are shown the preferred embodiments of this invention, and particularly referring to Fig. 1, thereference character 5 designates a railway refrigerator car in the process of being precooled after becoming overheated while being returned to a shipping point for some perishable commodity.

At this point, it will be stated that although the various figures of the drawings disclose only railway refrigerator cars, it is to be understood that refrigerator truck bodies and trailer bodies could just as well have been disclosed and the following description applied thereto. These disclosures of railway cars, therefore, are not to be considered as a limitation in construing the claims. For the purpose of illustrating the versatility of this inventio it will be assumed that the particular refrigerator body disclosed in Fig. 5 is intended to employ blocks of water-ice as the refrigerating medium en route. To receive these blocks of ice, the ends of the body 5 are provided with the conventional ice bunkers 6. These bunkers, of course, are constructed to permit air to circulate through the interior of the body with the interiors of the bunkers included in the path of air flow.

To adapt the body 5 for the precooling step embodying this inven ion, the various sidewalls and roof have had ap ied thereto a lining material to which carbon dioxide snow will.adhere. Any fabric material will be suitable, and it is suggested that an inexpensive fabric, such as burlap, manently secured to the said walls of the body if the car is to be maintained in service, at least for a substantial portion of its time, on runs or routes where facilities for precooling in accordance with this invention are provided. If certain refrigerator bodies are only intended to be temporarily employed as a part of this service, the snow retaining lining may be preformed as removable panels which may be readily detachably secured to the inner surfaces of the body walls.

It will be explained at this point that any fab-- ric covered-surface, or in fact any rough fibrous surface, when placed in the path of a stream of mixed carbon dioxide snow and vapor will accumulate a deposit of snow as a result of impingement of the snow against the surface. The rough,'fabric or fibrous lining for the walls of the refrigerator body 5 are prbvided for this purse. s. To accomplish precooling of the body 5, this invention contemplates feleasing into the interior of the bodya sufficient quantity of a mixture satisfactory temperature of carbon dioxide snow and vapor, at a sufficiently rapid rate, to completely fiood the internal space of the body with the vapor and to apply an appropriate layer of snow to the exposed sur- ,faces of the lining. To accomplish this result,

an exteriorly positioned source of supply of carbon dioxide, in liquid form, such source is designated by the reference character 7 and takes the form of a truck or trailer body that includes a tank completely enclosed in a suitable insulating material. Trucks suitable for this purpose are now available for handling a full load of approximately 3 /2 tons of liquid carbon dioxide. Larger trailer bodies are available for transporting six, seven, and eight ton loads. If, at certain shipping points, this precooling method is to be restricted to railway refrigerator cars, there are available insulated railway tank cars, each having a capacity suitable for storing. 24 tons of liquid carbon dioxide.

As a further modification, shipping centers for large quantities of perishable commodities may have installed fixed storage tanks which may be serviced by a truck of the type designated by the reference character 1 in Fig. 1. Fixed storage tanks may be of any desired capacity. The largest insulated, fixed tank forthe storage of liquid carbon dioxide so far constructed has a 125 ton capacity. Larger tanks may be provided if desired.

Although it is possible to carry out this precooling method with liquid carbon dioxide stored in uninsulated tanks, such as commercial cylinders, which are subjected to the temperature of the surrounding atmosphere, the process may be more eificiently employing liquid carbon dioxide which is maintained at a substantially constant subatmospheric temperature, and its corresponding vapor pressure. 5

When employed in its broad sense, the term "subatmospheric temperature is intended to cover all temperatures falling below a normal atmospheric temperature of 70 F' However, it

is employed. One

" has been determined that extremely low temperatures are more desirable and provide greater efiiciency and economy of operation; The most I range is from 32 F. to 40 F. At this time, liquid carbon dioxide is most frequently stored in such insulated tanks at a constant temperature of approximately 0- be employed. This lining may be perbe approximately 145 F. Liquid carbon dioxide stored at this temperature has a vapor pressure of approximately 305 pounds per square inch, absolute. When stored at 32". F., the vapor pressure of the liquid will be approximately 505 pounds per square inch, absolute, while at 40f F the vapor pressure will pounds per square inch, absolute.

'When the liquid carbon dioxide to'be used in carrying out this invention is stored in fixed tanks, the desired constant temperature may be maintained by employing-a commercial refrigerating machine which has its cooling coil lo ated in the vapor space of the tank. When'the liquid carbon dioxide is to be obtained from a mobile suitable source of supply unit, the tank of the unit will be charged at a with liquid carbon dioxide at a desired low temperature. .This mobile unitv will be provided with one or more bleed off valves which will beset for operation at a somewhat higher pressure. When the vapor pressure of the, liquid stored in the tank of this unit reachesthe pressure for which the bleed ofi valve is set, carbon dioxide vapor will be released and economically carried out by a dioxide vapors and snow to accomplish the per square inch is to The pressure of Liquid carbon such storage to the atmosphere and self-cooling or self-refrigerating of the remaining liquids will be accomplished as a result of vaporization of additional liquid to take the place of the vapors released through the valve. For example, if liquid carbon dioxide at a maximum pressure of 300 pounds be used in carrying out this method, the mobile unit may be charged with liquid carbon dioxide at, say, 200 pounds per square'inch. During supply to the shipping center serviced by the unit, the pressure of the stored carbon dioxide will rise as a result of normal input of heat through the insulation surrounding the tank. the stored liquid may rise until 300 pounds is reached. At this maximum'pressure, a sufficient amount of carbon dioxide vapors will be slowly bled from the tank to lower the pressure of the liquid. The closing pressure for the valve may be set at 275- pounds per square inch. From the time the pressure first reaches the maximum value of 300 pounds, the pressure within the tank of the mobile unit will be maintained between the opening and closing pressures for which the bleed off valve has been set.

By confining the liquid carbon used in carrying out this process in bulk storage tanks of the types referred to above, the liquid may be discharged at almost any desired rate. dioxide has been discharged from tanks through pipe lines varying from one inch to six inches in diameter. Discharge rates up to six tons a minute have been used commercially up to the present time. Discharge lines measuring from and one-half inches have been found tobe entirely adequate for carrying out this method.

It is the purpose of this invention to totally flood the interior of refrigerator car or truck bodies with a suflicient amount of mixed carbon desired cooling of the interior of the body and its walls to the desired low temperature and to applyan appropriate coating of carbon dioxide snow to the exposed surfaces of the car lining in a fraction of a minutes time.v This rapid precooling may be accomplished by delivering the liquid carbon dioxide to the vehicle body through either a one inch or a one and one-half inch discharge line having applied to its extremity a single discharge device. i

To accomplish this precooling operation with the mobile unit 1 and the hose line 8, the operator will merely step just inside the body 5 through the conventional loading doorway 9 and will release the carbon dioxide into the car body.

During the fraction of a minute that the liquid carbon dioxide is being discharged, the hose line should be manipulated; so that the stream will impinge against all of the exposed surfaces of the snow accumulating lining. By quickly swinging the discharge end of. the hose line around so that the discharge will be .directed against all the walls of the interior of the body 5, this snow deposit may be provided.

To indicate the ability of this ,type of carbon dioxide discharge to quickly cool heated spaces, it will be stated that the temperature of the discharged mixture is approximately -l10 F. and enclosed spaces heated "to a temperature in the neighborhood of1000 F. have been cooled to sub-zero temperatures as a result vof a carbon dioxide discharge of the illustrated character lasting approximately one minute.

Of course, flooding theinterior of a transtransit from the source of dioxide to be one inch to one portable refrigerator body of the illustrated character with carbon dioxide vapor expels from the space the heated air. It also creates an atmosphere in which it would be dangerous to work. With the loading door 9 wide open, however, the vapors will be permitted to escape rapidly. In the course of two or three minutes, an

observer will note that the whitish vapors have settled'within the space, as a result of this escape, and the top of the vapor blanket or mass within the space will be well defined and will be visible through the door opening 9. In approximately five minutes, the vapors charged into the refri erator space will have dissipated to a suflicient extent to enable workmen to safely enter the vehicle body for loading purposes.

The deposit of carbondioxide snow on the lined walls of the enclosure is still present after the vapors have escaped through the loading doorway. This carbon dioxide snow sublimes at F. and will continue to Z refrigerate the interior of the vehicle'body, while it sublimes. This prolonging of the refrigerating action during the loading period effects an initial refrigerating of the warm commodities. Because the carbon dioxide vapors liberated as a result of sublimation of the snow are more dense than air, these vapors will move downwardly along the sides of the body walls. and after reaching the floor level they will flow outwardly of the enclosure through the loading opening. In observing this action, it will be noted that the walls of the enclosure are covered with a fabric lining which has applied theretothe deposit of snow and a film or layer of vapors, traveling downwardly, will overlie the snow deposit. This combination of fabric, solid carbon dioxide, and vapor layers will very effectively insulate the interior of the enclosure against the input of heat through the walls of the refrigerator body.

After the refrigerator vehicle has been properly loaded, it is necessary to provide the en' upon to preserve the commodities while in transit. The vehicle of Fig. 1 is provided with the conventional ice bunkers 6 which are to be charged with blocks of ice for this purpose. Another methcd of refrigerating the commodities en route would be to top ice the same by discharging crushed or snow ice into the car for the purpose of filling the spaces between the boxes,= crates, or the like which contain the commodities and for applying a blanket or layer of the ice particles over the top of the load.

' This top icing method is illustrated in Fig. 3. If

the roof I ways of refrigerating the load while in transit.

' by shutting ,for many hours.

the present invention involves two entirely new methods. The first-of these new methods consists of entirely closing up the refrigerator body the door or doors-for the loading doorway and then discharging a second charge closure with the refrigerant which is to be relied entire space between the of carbon dioxide snow and vapors into the inof the special charging doors In or' Illa of Figs. 2

and 3, or by means of the permanent piping H and I2 disclosed in Figs. 4 to 6, inclusive. This second flooding of the sealed up enclosure provides a refrigerating temperature which will last If thedistance to he traveled will require several days, it will be necessary to unusually long transportation time, it becomes 4 re-flood the enclosure at designated points along through one side wall .of the car body and is the route. This re-flooding may be accomplished provided with a coupling 23 to which a hose line, in the same manner as the initial flooding, i. e.. such as that designated by the reference charthrough the special doors or through the peracter 8 in Fig. 1, may be connected for supplymanent piping. It will be appreciated that this '5 ing the line I l with carbon dioxide from a bulk method of refrigerating will not only maintain storage source. This pipe line extends around the perishable commodities at the desired low the interior of the car body, adjacent the roof, preserving temperature but will also provide the and is provided at suitable intervals with disenclosure with a carbon dioxide atmosphere that charge nozzles 24. These discharge nozzles are has a very .definite beneficial efiect in preserving illustrated in Fig. 5 as pointing both horizontally the commodities and preventing the growth of and vertically to deliver the released carbon dibecteriaoxide snow and vapor mixture both transversely The second new method of refrigerating the of the enclosure and downwardly. These dis-v load while in transit is fully illustrated in Fig. 3 charged jets or streams of snow and vapor will and involves'the combination of top icing and 1.5- sweep the side walls and the top wall or ceiling carbon dioxide flooding. In carrying out this of the enclosure and will deposit carbon dioxide method, the crushed or snow ice I3 is discharged snow on these lined surfaces. CEhe nozzles 24 into the interior of the body in the conventional are of suitable design to create a'back pressure way but the space between the top of the load in the line H which will'preven't thepressure and the inner surface of the car roof is not enof the carbon dioxide flowing through this line tirely filled with the layer or blanket of ice. A from dropping to a value which will permit snow chamber is left between the top of the ice blanketto form either in the line or in the nozzles. Dis-' and the inner surface of the roof. charge devices of this type are very common in After the enclosure is iced in this manner, the the prior art and are readily available on the loading d O 'S a e C os d a t e remaining open market. The majority of such devices opam W h is designated by the reference erate on the principle of permitting the carbon character M in Fig. 3, is flooded either through dioxide to ,be discharged through a constricted n of h d s D r y m a s f th permaorifice; This relatively small opening. creates nent P p l 0 S n in Figs- 4 0 the desired back pressure, and liberation of the elusive. Thisfloodins of th cham r it with a liquid carbon dioxide on the atmospheric side mixture of'carbon dioxide snow and Vap of the aperture permits sudden expansion which i a t mpe a r f appro im y 0 converts the liquid'to vapor and snow; will operate very effectively to retard melting of The percentage of snow produced as a rethe water-ice. The carbon dioxide snow of the suit of sudden expansion of liquid carbon dim u o s ll b deposited on the oxide depends on the temperature of the liquid. fa s tha o t chamber This SHOW Theoretically, liquid carbon dioxide stored at a posit will sublime in the course, of time and will temperature of 70 F. produces a discharge mixliberate additional vapors. The O l D ture which contains 29% snow, while liquid of the flooding mixture will not remain static barbon'dioxide tored an reI s t 0 F, proin the chamber l4 but will find its way into the 40 ,duces snow. The percentage of snow .con- VOidS between the particles Of water-ice and W111 tinues to increase as, the temperature of the provide the desired carbon dioxide preserving atstored liquid decreases. The latent heat of vamosphere for the commodities. If. as a result porization of carbon dioxide at different-temof unusually high tempera u Conditions id/ peratures has a very important bearing 'on the ability-of this medium to quickly-cool, the innec ssa y to reflood the enclosure, this may be volved spaces. Forexample, at 87.8? F, the acco p s ed n the sa e manner s h Original latent heat of vaporization is 0 B. t. 11-. per pound flooding. of carbon dioxide; at 4.0 F., it is 122 B. t. u. To return to the modified car structures shown per pound, and at 69-.9 F., it is 149.6 B. t. u. n the Se l fi s, it Will e Pointed out that 5 per pound. It is apparent, therefore, that the the car of Figs. 2 and 3 is prov ded h (10ers use of low temperature, low pressure liquid car 10 which are hinged to the side walls of the bon dioxide to carry out the stepsof either pr y, as at l5, and are adapted to be e a ed cooling oriefrigerating during transit is much closed by means of suitable latches l6. Fig. 3 more ei fective than theuse of uncontrolled, high discloses these doors ID as closing ports i which 5 temperature carbon dioxide, extend entirely through the walls of the car body In Fig. 5, the loaded perishables are diagramand open into the upper portion of th n matically designated by the reference character .sure. 25. Afabric cover 26 is applied .to the top' of The door lflc of'Fig. 2 is of special construe this load- This fabric covering will function to tion and will function to re ieve exeeesivepres- 6 accumulate a blanket or layer of carbon dioxide sure within the enclosure. This exce'ssivepressnowswhich 11 sublime m .tramsitv and, 1 sure may be c e d as a result o sublimation of course, absorb heat from the load and from the the' carbon dioxide snow. This door Illa is pro- 1 interior of the car' body as a result of this change vided with a suitable handle I8 for swinging it of t t about its hinges 20. A spr n I9 is interposed Fig. 6 discloses a modificationof the fixed between end brackets 2| and 22, carried by the piping idea illustrated in Figs. 4 and 5. In this door and th a d p v y- This sp n Fig. 6, the pipe line I2 is located in the space .27 will function to retain the door lllafclosed at all between the inner and outer walls "of the side times except when an excessive vapor pressure of the car body, which space usually receives the exists in the enclosure. When such an excessive 7o insulating materialemployed in the construction -vapor pressure does exist, the door will open 4 of the-body. This piping. I2 is provided-with a .to let out sufficient vapor to reduce the pres-, suitable number of discharge nozzles or jets28 sure to a desired lower value. 1 that extend from the piping into the interior. of

In Figs. 4 and 5, the car bpdy is illustrated as the car body. The principal advantage in tisbeing provided with a pipe line which extends sembling the piping within the side wall strucly rapid rate to quickly lower temperature and its .ture of the car is to protect the piping from damage as a. result of rough handling of the sfreight and to avoid obstructing any portion of the space provided by the car for transporting a. pay load.

Fig. 3 discloses the refrigerator car. structure of Fig. 2 when used for carrying out the combined top icing and carbon dioxide flooding method for refrigerating the perishable commodities en route. This figure additionally discloses the discharge nozzle 29; to be used on the hose line 8 and a control valve 3|] by means of which the operator is permitted to start and stop the discharge 'of carbon dioxide snow and vapor through the nozzle.

It is to be understood that the forms of this invention herewith shown and described are to be taken as preferred examples of the same, and that variouschanges in the shape, size, and arrangement of parts may be resorted to without departing from the spirit of the invention or the scope of the subjoined claims.

Having thus described the invention, I. claim:

1. A method of refrigerating perishable commodities and precooling the vehicles employed for transporting the same, comprising applying to the walls of the commodity transporting space of each of such vehicles a material to which carbon dioxide snow will adhere, releasing into the space liquid carbon dioxide to form a mixture of carbon dioxide snow and vapor at a sufficientthe temperature of the space to that desired for loading, controlling the direction of release so that the mixture will strike said walls and, as a result of such impinge ment, deposit a layer of snow on the covering material which will prolong the refrigerating action beyond the period of discharge while subliming, and loading thedvehicle with th perishable commodities to be transported while the temperature in the space is still at a desired low value.

2. A' method of refrigerating perishable commodities and precooling the vehicles employed for transporting-the same, comprising maintaining in bulk storage a supply of liquid carbon dioxide at a substantially constant subatmospheric corresponding vapor pressure, conducting the carbon dioxide to each one of the vehicles to be r frigerated through a relatively large diam'etere confining flow path as a liquid and at substantially the storedtemperaand, after closing ture and pressure, effecting sudden expansion of the liquid into the commodity transporting space of the vehicle to quickly flood the same with a mixture of carbon dioxide snow and vapor whereby the subzero temperature of the discharge will effect refrigeration of the vehicle, prolonging the refrigerating action beyond the period of discharge by accumulating a substantial layer of carbon dioxide snow on certain walls of the space of the vehicle, and loading the vehicle with the perishable commodities to be transported while the temperature in the space is still'at a desired low value.

3. A method: of refrigerating perishable com-. modities and precooling the vehicles employed for transporting the same, comprising applying to the walls of the commodity transporting space bon dioxide snow will adhere, maintaining in bulk storage a supply'of liquid carbon dioxide at -43, substantially constant subatmospheric temperature and its corresponding vapor-pressure, com 7 of the vehicle,

of-each of such vehicles a material to which care. 7

to be refrigerated through a relatively large diametered confining fiow path, and at substantially the stored temperature and pressure, effecting sudden expansion of the liquid into the said space of the vehicle to quickly flood the same wth a mixture of carbon dioxide snow and vapor and in such a manner that a layer of snow will be deposited on the wall covering, and loading the vehicle with th perishable commodities to be transported While the temperature in the space is still at a desired low value.

.4.'A method of refrigerating perishable commodities and precooling the vehicles employed for transporting the same, comprising applying to the walls of the-commodity transporting space of each cnecf such vehicles a material to which carbon dioxide snow will adhere, releasing into the space liquid carbon dioxide to form a mixture of carbon dioxide snow and vaporat a sufficiently rapid rate to quickly lower the temperature of the space to that desired for loading, controlling the direction of release so that the mixtur will strike said walls and, as a result of such impingement, deposit a layer of snow on the covering material which will prolong the refrigerating action beyond the period of release while subliming, loading the space ofthe vehicle during the sublimation period of the carbon dioxid snow, the loading door of the vehicle, charging a refrigerant into the vehicle space to maintain the desired refrigerating temperature en route.

5. A method of refrigerating perishable commodities and precooling the vehicles employed for transporting the same, comprising releasing into the commodity transporting space of each one of such vehicles liquid carbon dioxide to form a mixture of snow and vapor, the rate of release the space, loading the vehicle space during the v sublimation period of the carbon dioxide snow,

and, after the vehicle has been loaded, charging a refrigerant into the vehicle space to maintain the desired refrigerating temperature en route.

6. A method of refrigerating perishable commodities and precooling the vehicles employed for transporting the same, comprising maintaining in bulk storage a supply of liquid carbon dioxide at a, substantially constant subatmospheric temperature and its corresponding vapor pressure, conducting the carbon dioxide to each one of such vehicles to be refrigerated through a relatively large diametered confining flow path as a liquid and at substantially the stored temperature and pressure, effecting sudden expansion of the liquid into the commodity transporting space of the vehicle to quickly flood the same with a mixture of carbon dioxide snow and vapor whereby the subzero temperature of the discharge will effect refrigeration of the vehicle space, prolonging the refrigerating action beyond the periodof discharge by accumulating a substantial layer of carbon dioxide snow on certain walls of the space loading the vehicle space during the sublimation period of the carbon dioxide sriow, and, after the vehicle has been loaded, charging .a refrigerant into the vehicle space to maintain the desired refrigerating temperature en route.

7. A method of. refrigerating perishable commodities and precooling the vehicles employed I carbon dioxide snow the said'space liquid-carbon dioxide to form a carbon dioxide snow will adhere, maintaining in bulk storage a supply of liquid carbon dioxide at a substantially constant subatmospheric temperature and its corresponding vapor pressure, conducting the carbon dioxide liquid to each vehicle to be refrigerated through a relatively large diametered confining flow path, and at substan- 1Q loading door of the tially the stored temperature and pressure, effecting sudden expansion of the liquid into the space of the vehicle to quickly flood the same with a mixture of carbon dioxide snow and vapor and in such a manner that a layer of snow will .15 be deposited on the wall covering, loading.v the vehicle space during-the sublimation period of the carbon dioxide snow, and, after the vehicle has been loaded, charging a refrigerant into the vehicle space to maintain the desired refrigeratg ing temperature en route.

8. A method of refrigerating perishable commodities and precooling the vehicles employed for transporting the same, comprising applying to the walls of the commodity transporting space '25 of each one of such vehicles a material to which Will adhere, releasing into mixture of carbon dioxide snow and vaporat a sufliciently rapid rate perature of the space to that desired for loading, controlling the direction of release so that l the mixture will strike said wall and, a a result ,of such impingement, deposit a layer of snow on the covering material which will prolong the refrigerating action beyond the period of release while subliming, loading the vehicle-space during the sublimation period of the carbon dioxide snow, and, after closing the loading door of the vehicle, releasing-into said space a second charge 40 of carbon dioxide snow and vapor to maintain Y the desired refrigerating temperature en route and to create a preserving atmosphere for'the transported commodities.

9.,A methodof refrigerating perishable commodities and precooling the vehicles employed for transporting the same, comprising releasing one of such vehicles liquid carbon dioxide to form a mixture of snow and vapor, the rate of release bein sufiicient to quickly lower the temperature of the space to the value'desired for loading, prolonging therefrigerating action beyond the period of release by accumulating a substantial layon certain walls of dioxide snow and vapor to maintain the desired refrigerating temperature en route and to create. a. preserving atmosphere for the transported commodity.

10. A method of refrigerating perishable com -modities and precooling the vehicles employed I g snow and vapor.

for transporting the same, comprising maintaining in bulk storage a supply of liquidcarbon dioxide at a substantially constant subatmospheric temperature and its corresponding vapor to quickly lower the tem- 30 into the commodity transporting space of each ing space of the vehicle to quickly-flood the same with a mixture of carbon dioxide snow and vapor whereby the subzero temperature of the discharge will efiect refrigerationof the vehicle space, prolonging the refrigerating action beyond the period of discharge by accumulating a substantial layer of carbon dioxide snow on certain walls of the space of the vehicle, loading the vehicle space during the sublimation. period of the carbon dioxide snow, and, after closing the I vehicle, releasing into said space a second charge of carbon dioxide snow and vapor to maintain the desired refrigerating temperature en route and to create a preserving atmosphere for the transported commodity.

11. A method of refrigerating perishable commodities and precooling the vehicles employed 'for transporting the same, comprising applying 0 to the walls of the commodity transporting space of each one of such vehicles amaterial to which carbon dioxide snow will adhere, releasing into the said space liquid carbon dioxide to form a mixture of carbon dioxide snow and vapor at a sumciently rapid rateto quickly lower the temperature of thespace to that desired for loading, controlling the direction of release so that the mixture will strike said walls and, as a result 7 of such impingement, deposit a layer of snow on the covering material which will prolong the re frigerating action beyondthe period of release while subliming, loading the vehicle space with the packed containers of perishable commodities while leaving the space unoccupied between the tops of the containers and the roof of the vehicle, covering the tops of the uppermost containers with a layer of water-ice particles, having a depth which will only partly fill the aforesaid unoccupied portion of the space, and, after closing the loading doorof the vehicle, flooding the unoccupied portion of the space in the top portion of I the vehicle with an additional discharge of carbon dioxide snow and vapor.

12. A method of refrigerating perishable comfor transporting the same, comprising releasing mto the commodity transporting space ofeach one of such vehicles liquid carbon dioxide to form a mixture of snow and vapor, the rate of release being suflicient to quickly lower the temperature of the space to the value desired for loading, prolonging the refrigerating action beyond the period of'release by accumulating a substantial layerof carbon dioxide snow on certain walls of the space, loading the vehicle. spacewith the packed containers of perishable commodities while leaving the space unoccupied between the tops of the containers and thereof of the vehicle, covering the tops of the uppermost containers with a layer of water-ice particles having a depth which will only partly fill the aforesaid unoccupied portion of the space, and, after closing the loading door of the vehicle, flooding the' of the space in the vehicle A unoccupied portion 1 discharge of carbon dioxide with an additional 13. A method of refrigerating perishable comfor transporting the same, comprising mai t i pressure, conducting the carbon dioxide to each ing in bulk storage a supply of liqui ca b m.

cm of suchvelpcles to be refrigerated through a relatively large diametered confining flow path @as a liquid and at substantially the stored temperature'and pressure, effecting sudden expan- 81911 of the liquid into the commodity transport oxide at a substantially constant subatmospheric temperature and its sure, conducting thecarbon dioxide to each one i of such vehicles to be refrigerated through a relmodities and precooling the vehicles employed g the vehicles employedcorresponding vapor pres atively large diametered confining fiowpath as a assaeoo liquid and at substantially the stored temperature and pressure, efiecting sudden expansion of the liqu d into the commodity transporting space of the vehicle to quickly flood the same with a mixture of carbon by the subzero temperature. of the discharge will effect refrigeration of the vehicle space, prolonging the refrigerating action beyond the period of discharge by accumulating a carbon dioxide snow on certain space of the vehicle, loading the vehicle with the packed containers of perishable commodities while leaving the space unoccupied between the tops of the containers and the roof of the vehicle, covering the tops of the uppermost containers with a layer of water-ice particles having a depth which will only partly fill the aforesaid unoccupied portion of the space, and, after closing the loading door of the vehicle, flooding the unoccupied portion of the space in the vehicle with an additional discharge of carbon dioxide snow and apor.

14. A method of refrigerating perishable cominodities and precoo-ling the vehicles employed for transporting the same, comprising applying tothe walls of the commodity transporting space of each one of such vehicles a material to which carbon dioxide snow will adhere, maintaining in bulk storage a supply of liquid carbon dioxide at a substantially constant subatmospheric temperature and its corresponding vapor pressure, conducting each carbon dioxide liquid to the vehicle to be refrigerated through a relatively large diametered confining flow path, and at substantially the stored temperature and pressure, effecting sudden expansion of the liquid into the commodity transporting space of the vehicle to quickly flood the same with a mixture of carbon dioxide snow and vapor and in such a manner that a layer of snow will be deposited on the wall covering, loading the vehicle space with the packed containers of perishable commodities while leaving the space unoccupied between the tops of the containers and the roof of the vehicle, covering the tops of the uppermost containers with a layer of water-ice particles having a depth which will only. partly fill the aforesaid unoccupied portion of the space, and, after closing the loading door of the vehicle, flooding the unoccupied portion of the space in the vehic charge of carbon dioxide snow and vapor.

15. A method of refrigerating perishable commodities in transit, comprising packing the commodities in a transportation vehicle while leaving a space between the top surface of said commodities and the roof of the vehicle, filling a p rt of the depth of said space with a layer. of water-ice particles applied to the top of said commodities. and, after closing flooding the interior of the larly the unoccupied space in the top portion of the vehicle with a mixture of .ca bon dioxide snow and vapor. 16. Means for refrigerating perishable oomvehicle and particumoditieacomprising .a transporting vehicle hav-- fabric lining app apiping system ining a refrigerating space, a to thewalls of said space, stalled in said vehicle and discharge devices opening into. the said refrigerating space and directed relative to said lining so as to apply a coating of carbon dioxide snow dioxide snow and vapor where- K e with an additional dissubstantial layer of walls of the saidthereto, a storage unit for of liquid carbon dioxide exteriorly of the vehicle and at a subatmospheric temperature and its corresponding vapor pressure, and means for connecting the storage unit to the piping system for conductng the liquid carbon dioxide to the interior ofthe vehicle and' releasing it so as toform a mixture of vapor and snow in sufficient quantitles to completely flood the space with vapors and to apply the said coating of snow to the ex: posed surface of the fabric lining.

1'7. A method of refrigerating perishable commodities and pre-cooling the vehicles employed.

for transporting the same, comprising releasing into the commodity transporting space of each one of such vehicles liquid carbon dioxide to form a mixture of snow and vapors, therate of a release being sumcient to quickly lower the temthe loading door of the vehicle,

having a plurality of perature'of the vehicle space to the value desired for loading, prolonging the refrigerating action beyond the period of-release by accumulating a substantial layer of carbon dioxide snow on certain walls of the space, loading the vehicle space with the perishable commodities to be transported while the temperaturein the space is still at a desired low value, and charging a refrigerant into the vehicle to maintain a desired refrigerating temperature en route...

18. A method of refrigerating perishable commodities and pre-cooling the vehicles employed' for transporting the same, comprising maintaining in bulk storage exteriorly of all of the commodlty transporting vehicles a supply of liquid carbon dioxide at a substantially constant subatmospheric temperature and its corresponding vapor pressure, successively conducting the liquid carbon dioxide to each one of such vehicles to be refrigerated through a flow path which will provide a relatively high volume of flow and at substantially the stored temperature and pressure, effecting sudden expansion of the liquid into the commodity transporting space of the vehicle to quickly flood the same with a mixture of carbon dioxide snow and vapors, loading the vehicle space with the perishable commodities to be transported while the temperature in the space is still at a desired low value, and charging a refrigerant into the vehicle space to maintain a desired refrigerating temperature en route.

19. A method of refrigerating perishable commodities and pre-cooling the vehicles employed for transporting the same, comprising releasin into the commodity transporting space of each one of such vehicles a mixture of snow and vs.- pors resulting from the sudden expansion of liquid carbon dioxide, the rate of release being sufficient to quickly lower the temperature of the vehicle space to the value desired for loading, rolonging the refrigerating action beyond the period of release by accumulating 'a substantial layer of carbon dioxide snow on certain walls of the vehicle space, loading the vehicle space with the packed containers of perishable commodities while leaving the space unoccupied between the top of the pile of containers and the vehicle, and covering the top of. the pile of containers with a layer of water-ice particles to a desired depth to eflect refrigeration of the commodities en route.

ALLYN HARRIS.

maintaining a supply roof of the

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