US2447249A - Method of refrigerating an article by contact with a vaporizable refrigerant - Google Patents

Description

R. H. HILL 2,447,249 METHOD OF REFRIGERATING AN ARTICLE BY CONTACT WITH A VAPORIZABLB REFRIGERANT Filed Oct. 13, 1944 2 Sheets-Sheet J.

Aug. 17,

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R. H. HILL 2,447,2 METHOD OF REFRIGERATING AN ARTICLE BY CONTACT WITH A VAPORIZABLE REFRIGERANT Filed Oct. 13, 1944 2 Sheets-Sheet 2 F0 I a q IIII IF I 1 E :1 l o '1 Melt Or i- Q Q $0581"! .5. JIZ Z Z Patented Aug. 17, 1948 METHOD OF REFRIGERATING AN ARTICLE BY CONTACT WITH A VAPORIZABLE RE- FRIGERANT Robert H. Hill, Elgin, Ill., assignor to The Marison Company, Elgin, 111., a corporation of Illinois Application October 13, 1944, Serial No. 558,566

2 Claims. 1

This invention relates to a method of and an' apparatus for refrigeration.

In the art of refrigeration several methods of frigerating articles, the apparatus including producing the desired low temperature in the articles have been used. One common method ofrefrigeration entails the use of water ice and where a temperature below the freezing point of water is required, a salt is mixed with the water ice to attain the required low temperatures. Another method entails the use of solidified carbon dioxide 'gas and placing the such Dry Ice in contact with or adjacent to the article to be refrigerated. A third method involves the use of sealed containers of frozen brine, commonly known as cold cans, the containers being likewise placed in contact with or adjacent to the article. A fourth method comprises extracting heat from the article by mechanical means operating in the vicinity of the article.

The above-mentioned refrigerating methods are subject to certain limitations, particularlyv when the problem is to refrigerate articles in transit. While water ice is nearly ideal for relatively higher refrigerating temperatures, e. g. above 40 F., it is not satisfactory for lower temperatures since salt must beadded to lower the melting point of the ice and this involves additional expense. In adddition, the brine which results is quite corrosive to the vehicle structure and in the case of railroads, to the various switches and controls along the right-of-way. Dry Ice eliminates the corrosive features of brine, but it is quite expensive and furthermore is. not readily controllable as to the temperature produced. Cold cans-are not as expensive as Dry Ice, but

they must be returned for refreezing, which in volves handling and hauling unfrozen cans perhaps for considerable distances. Mechanical refrigeration, though satisfactory from the standpoint of creating and holding a desired tempera-.

means for effecting relative movement between a quantity of refrigerant and the articles to be refrigerated.

In general, this invention comprises utilizing liquid air as the refrigerant, a supply of the liquid air being placed in a receptacle in a chamber and then either movin the articles through the chamber in contact with the liquid air, or regulating the flow of liquid air into the chamber, the temperature being varied by altering the quantity of the liquid air'used and the time during which the articles are exposed to it. There are three forms of the method by which this invention may be carried out. In the first, the liquid air is placed in a receptacle in an enclosed chambar near the top thereof and the articles to be refrigerated are placed upon the floor or elsewhere near the bottom of the chamber.- The most useful in refrigerating vehicles, rooms or warehouses. A thermostatic control may be in corporated in the spraying device to maintain an even temperature.

In the second form, the articles to be refrigerated are mounted upon a conveyor, rack or the like andare inserted into a chamber beneath a spray of liquid air emanating from a perforated ture, creates maintenance problems b'oth in-the form of periodic servicing and breakdowns en route.

The principal object of this invention is to provide a method of refrigerating articles which is free from most of the limitations of the methods outlined above. More specifically, the object of this invention is to provide'a refrigerating method container placed over the conveyor. This form is useful for quick-freezing the articles, that: is, for frozen foods'and the like which must be frozen quickly and then transported in a frozen state. When a conveyor is used, the temperature of the articles is a function of the speed of the conveyor and quantity of liquid air used in the spray per unit time. J

The third form is similar to the second, ex-

cept that the articles are immersed in the liquid needed to freeze them and the quantity of liquid air used in the process.

Other and further objects of the present invention will be apparent from the following description and claims and are illustrated in the accompanying drawings which, by way of illusthe best mode in which I have contemplated applying that principle. Other embodiments of the invention embodying the same or equivalent principle may be usedand structural changes may be made as desired by those skilled in the art without departing from the present invention and the purview of the appended claims.

In the drawings: Fig. 1 is a cross-section through a chamber in which 'one form of this invention is utilized;

Fig, 2 is a cross-section through an apparatus utilizing another form of the invention; and

Fig. 3 is a cross-section through a chamber utilizing still another form of this invention.

Referring to Fig. l, the chamber I!) there shown is provided with a door II in one wall thereof through which articles to be refrigerated are passed. The articles are shown at |2 resting upon the floor |3 of the chamber and spaced from one another to permit circulation of the refrigerant around them. The articles may be mounted on stands (not shown), if desired, to permit circulation of the refrigerant around all sides thereof. Near the top H of the chamber and preferably at or near a corner is an insulated receptacle l5 lined with a suitable substance l6 such as steelwhich will not deteriorate upon contact with a refrigerant at -300 F. Receptacle I5 is almost completely filled with liquid air |1 through a pipe l8 passing through the top of the chamber. Pipe I8 is closed by a cover |9 to retain all of the gaseous refrigerant within the receptacle. The gaseous refrigerant occupies the space 20 and is emitted into the chamber through a conduit 2|, a valve 22 and a suitable nozzle 23.

The bottom of receptacle |5 has a pipe 24 leading therefrom to one or more branches 25 from which the liquid air may be sprayed into the chamber either upon a tray 21 from which it evaporates into the chamber or directly into the chamber or onto articles placed therein.

In Fig. 2, the chamber is shown at 38 having openings 3| and 32 at opposite ends thereof. Within chamber 36 and extending substantially from one open end to the other is an endless belt conveyor comprising a pair of drums 33 and which causes the upper or load side of conveyor belt 31 to move to the left. Articles to be refrigerated such as packages 42 are placed upon the conveyor belt 31 through opening 3| in chamber and are removed through opening 32. A platform 43 positioned near drum 34 receives the packages as they come off conveyor belt 31.

Directly below the load side of conveyor belt 31 is a receptacle 44 in which is stored a quantity of liquid air 45. A pipe 46 communicates with the interior of receptacle 44 and conducts the liquid air to a pump 41, the outlets or high side of which is connected to a riser 48 which empties into a tank 49 located above conveyor belt 31. The bottom of tank 49 is perforated or it may be provided with a plurality of nozzles 50 which direct the liquid air upon the articles 42 as they pass through the chamber. A belt 5| and pulley 52 connected to pulley 39 of'motor 38 supply the motive power for pump 41. The cold air resulting from the gasification of the liquid. air may 4 pass out of chamber 30 through opening 3|, thereby serving to pre-cool the packages 42 before they are sprayed by the liquid air.

In the modification shown in Fig. 2Xthe rate of freezing is very rapid since the ar icle to be frozen, viz. packages 42 come in direct contact with the liquid air. The depth of freezingcan, of course, be regulated by the speed with which the packages are passed through the chamber, and this speed may even be such that the packages are merely cooled. Thus the temperature of the packages as they leave the chamber may be regulated by regulating the speed of the con- It is understood, of course, that suitable means is provided to render pump 41 a constant volume pump, since the quantity of liquid air leaving tank 49 is constant. It will be noted that the liquidair, after it leaves conveyor 31 drains back into receptacle 44.

T-he modification shown in Fig. 3 differs from the modification shown in Fig. 2 in that the packages are immersed in the liquid air instead of being sprayed by it. Referring to Fig. 3, the refrigerating apparatus is comprised of a chamber 55 having open ends 56 and 51. Adjacent open end 51 is a well or tank 58 which is formed by building the floor of chamber 55 at a lower level at end 51 than at end 56. Well 58 is filled with liquid air 59 which as it changes from liquid to gaseous state rises and flows toward end 56. The roof of chamber 55 ma be depressed at 66 to form a dividing wall and constrain a portion of the gasified refrigerant to travel in the direction of open end 56.

Two conveyors are used. The first operates entirely outside the liquid air well 58 and comprises an endless belt 6| passing over drums 62 and 63 mounted on supports or stands 64 and 65, respectively, with a motor 66 connected by a pulley 61 and belt 68 to a pulley 69 on drum 63 for driving the conveyor .belt 6|. The direction of rotation of motor 66 is such'that the load side of conveyor belt 6| is moved to the left as viewed in Fig. 3. Thus opening 56 constitutes the entrance or loading end of the chamber. The articles 10 to be frozen are moved through-the cold air escaping from well 58 and are thus precooled. The articles drop into the liquid air 59 when they leave conveyor 6|.

The second conveyor operates partly in the liquid air 59. It is comprised of an endless belt 1| passing around a drum 12 mounted on a stand 13 at the bottom of well 58, and around a drum 14 mounted on a stand 15 angularly disposed with respect to the sides of well 58. Stand 15 is located outside well 58 so that the end of belt 1| supported thereby is likewise outside the well.

'A second drum 16 also mounted on stand 15 serves to raise the slack side of belt 1| over the edge of well 58. A motor 11 connected by a pulley 18 and belt 19 to a driven pulley 86 on drum 14 supplies the motive power for belt 1 The direction of rotation of motor 11 is such that the drive side of conveyor belt 1| is moved to the left as viewed in Fig. 3, thus causing the articles which drop into the liquid air 58 and upon conveyor belt 1| to be moved through open end 51 upon an unloading platform 8| exterior of the well. A guide plate 82 above drum 12 constrains the articles to temperatures is available.

is theoretically twice the power required to produce a quantity of Dry Ice having the same heat abstracting capacity, the raw material for liquid air is free whereas the carbon dioxide used to form Dry Ice must be manufactured. The liquid air is easily handled and conveyed by tanks and pipes, whereas Dry Ice must be formed .into blocks, wrapped and then carried to the place where it is to be used. It is well established that the most rapid heat transfer between substance existing in different phases, e. g. liquid and gaseous phases, is between a surface and a boiling liquid, which situation obtains in the foregoing examples when the articles are immersed or in contact with the liquid refrigerant.

It is understood that the foregoing descriptio is merely illustrative of the preferred embodiments 'of this invention and .that the scope of this invention is not to be limited thereto but is to be determined by the appended claims. It is to be understood further that although liquid air is admirably suited to the refrigeratin methods disclosed herein, said methods are readily adaptable to other liquid refrigerants which possess the physical property of liquifying at extremely low temperatures and passing in a gaseous state while still at a low temperature.

Thus, while I have illustrated and described preferredembodiments of the invention, it is to be understood that these are capable of variation and modification and I therefore do not wish to be limited to the precise details set forth but desire to avail myself of such changes and alterations as fall within the purview of the following claims.

I claim: Y

1. The method of refrigerating an article which comprises providing a refrigerant which is adapted to pass from liquid to gaseous states, said refrigerant being provided in a chamber in both liquid and gaseous states, prec'ooling the article with the gaseous refrigerant while moving the article through a portion of the chamber, then continuously wetting the article with the liquid refrigerant during its movement throughout the remaining portion of the chamher and regulating the final average temperature of the article by the speed at which it is moved through the refrigerant.

2. The method of refrigerating an article which comprises providing a refrigerant which is adapted to pass from liquid to gaseous states, said refrigerant being provided in a chamber in both liquid and gaseous states, precooling the article with the gaseous refrigerant while moving the article through a portion ofthe chamber. flowing the liquid refrigerant over the article during its movement throughout the remaining portion of the chamber and regulating the final average temperature of the article by the speed a at which it is moved through the refrigerant.

ROBERT H. HILL.

REFERENCES orrEn The following references are of record intbe file of this patent:

UNITED STATES PATENTS Diserens et a1. Feb. 2, 1948

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