US2479867A

US2479867A - Process and apparatus for refrigeration

Info

Publication number: US2479867A
Application number: US639582A
Authority: US
Inventors: Theodore W Rosebaugh
Original assignee: Shell Development Co
Current assignee: Shell Development Co
Priority date: 1946-01-07
Filing date: 1946-01-07
Publication date: 1949-08-23
Anticipated expiration: 1966-08-23

Description

Aug. 23, 1949. T. w. ROSEBAUGH 2,479,367 PROCESS AND APPARATUS FOR REFRIGERATION Filed Jan. 7, 1946 s Sheets-Sheet 1 l l l g I l l I I Power Suppiq lnvenl'orl Theodora W- Roszbauqh Eq his MTorneqi 1949- T) w. ROSEBAUGH 2,479,867

PROCESS AND APPARATUS'FOR REFRIGERATION Filed Jan. 7. 1946 s Sheets-Sheet 2 \nvenfor Theodore W. Roscbauqh.

BL; hKs Aflorneq'.

Aug. 23, 1949. T. w. ROSEBAUGH 2,479,367

PROCESS AND APPARATUS FOR REFRIGERATION Filed Jan. 7, 194a s Sheets-Sheet s Leads m, w W M 8 6 W l m m .w, M w I a F. 0 v6 m o .A m F kl 6 m m U- o T .h 5 Z A. m 6 O v 2 l H. ,o v. .m o F o 0 V fi m o 0 F m. 0 4 F 5: M. I i. z 2.

Patented Au 23, .1949

UNITED STATES PATENT OFFICE] rRooEss AND APPARATUS FOR REFRIGERATION Theodore W. Roscbangh, Oakland, Calif aasignor to Shell Development Company, San Francisco, .Calltga corporation of Delaware Application January I, 1946, Serial No.- 639,582

8 Claims.

This invention relates to the cooling or refrigeration of foodstuffs and is particularly concerned with the safe and economical preservation of foodstuffs during storage.

The invention is primarily concerned with keeping fresh foodstuffs at a sufllciently low temperature so that deterioration of the foodstuffs is prevented.

It is an object of this invention to provide new and useful process and apparatus for the refrigeratiomof foodstuffs using expendable liquefied gas or mixture of liquefied gases.

It is another objecto'f thisinvention to provide a new and useful refrigeration system which may be adopted for household use or use in mobile equipment.

It is a further object of this invention to provide a process and apparatus using liquefied air as an expendable refrigerant.

It is another object of this invention to provide .part of the liquid air container shown in Figure Figure VIis a sectional view taken on line VI-VI of Fig. IV.

Referring to Figures I and n numeral i represeats in general an insulated refrigerator cabinet a safe system for discharging liquefiedair from containers thereof for use in refrigeration.

It is another object of this invention to provide a rapidly responsive refrigeration control for liquefied air refrigeration systems.

It is a further object ofmy invention to provide a refrigeration system in which liquefied air is discharged into the refrigeration space.

By the term liquid air.I include all liquefied mixtures of oxygen and nitrogen. In other words I include liquid air consisting'of oxygen and nitrogen in the proportions they occur in nature as well as liquid air'produced as'a by-product of industrial processes wherein the proportions of havingan insulatedhinged door- 2. Located in the refrigerator compartment are shelves 3 upon which foodstuffs to be cooled or preserved may be placed.

In the upper part of the cabinet is located a, deep freeze section t having a lid or hatch 5 enabling the interior of this deep freeze compartment to be reached without opening the door 2. The bottom 6 of the deep freeze section is perforated'so that circulation of air through the deep freeze compartment is readily effected.

A duct 1 is located in a depression in the inside back panel of the refrigerator. This duct is so arranged that it is preferably flush with the inside back panel and is located within the insula-' tion 8 which surrounds the refrigerator compartment. Theduct I extends upward and terminates ,in the deep freeze compartment 4'. The. duct ex tends in a downward direction to join the neck 9 oxygen and nitrogen may vary considerably from the proportions occurring in nature.

The further advantages and objects of my in 'vention will be apparent from the following description of a household refrigerator utilizing the invention.

Referring to the accompanying drawings:

Figure I is a front elevation of a household refrir'erator using my invention.

Figure II is a vertical section taken along the 4 line II-II of Figure I; I

Figure III is a longitudinal section of a railroad refrigerator car showing the installation of my invention.

Figure IV is an enlarged fragmentary sectional view showing detail of the upper part of the liquid air container and part of trough shown in Figure ofa Dewar fiask- Iii located inside the insulation 5 below the refrigerator compartment A riser or eduction pipe it extends from near the bottom of the Dewar flask upward through the refrig erator compartment and terminates in a shallow evaporating p an l2 located underneath the ice trays it. The lower end of the riser pipe ter- .minates in a frusto-conical shaped element l4. 7

The eduction pipe II has fins 15 on its outer v surface where the eduction pipe is exposed to the atmosphere of the refri erator comp rtment. The

' Dewar flask it is provided with a filling spout l6 which terminates at its o ter end underneath V the door 2 of the refrigerator.

.Thefspout is provided with a snap lid I! which normally covers the outer end of the snout.

Located in the Dewar flask and pos tioned underneath the fru tn-co ical sh ped. element H is a small electrical heating unit '8. T e electrical heating unit it! is connected in series with an adjustable thermostat i9 and to a source ofelectric current by suitable insulated wiring.

The operation of the refrigerator system shown in Figures I and II is as follows:

The Dewar flask is filled withliquid air 20 from an outside source through the filling spout l6. This liquid air isa temperature of about -315 F. varying slightly upon'its composition.

If the temperature of the air in the refrigerator compartment is higher thana predetermined orating pan l2.

'superatmospherio pressure temperature desired, then the thermostat is will close a circuit causing current to pass to the electric heating element I8 located in the bottom of the Dewar flask ill. The heating element i8'is preferably of the usual resistance type and upon the supplying of sufllcient heat will quickly cause an ebullition of vaporized liquid air-in its proximity. This vaporized liquid air will travel upward through the eduction pipe H and in so doing will entrap some liquid air in an unvaporized state. There, therefore, will be produced in eduction pipe ii an ascending column of liquid air in a vaporized and in an unvaporized condition. The unvaporlzed liquid air upon being discharged from the upper end of the eduction pipe 8 i will form a pool in the evaporating pan i2 and will continue to change into the vaporized state absorbing its latent heat of vaporization from the contents of the refrigerator compartment.

I'he vaporized liquid air from the evaporating pan i2 and the vaporized air carried upward in theeduction pipe ll will flow downward through the refrigerator compartment (owing to the greater density of the cold vaporized air) and will also serve to eifectively refrigeratethe contents of the compartment. A lower temperature than in the refrigerator compartment will be produced in the deep freeze section 4 owing to the proximity of the unliquefled air in the evap- Any vaporization which takes place from the surface of the liquid air in the Dewar flask I will becarried upward through the duct i into the top of the deep freeze section and this cold vaporized air also serves to increase the refrigerating effect in the deep freeze section.

The ice trays l3 located above the evaporating pan I 2 are efl'ectively located so that water-ice may be readily produced.

As will be apparent to those skilled in the art, the cold vaporized liquid air ascending through the duct B will withdraw heat from the refrigerator compartment in its upward passage. For this purpose the exposed wall of the duct is preferably made of metal such as copper or other highly heat conductive metal.

The liquid air and vaporized liquid air ascending through theeduction pipe it will likewise withdraw heat from the interior of the refrigerator compartment and in order to facilitate this action the fins IE on the eduction pipe I! are provided. In order to avoid the creation of a in the refrigerator compartment suitable vents are provided.

In Figure HI. I have shown a railroad refrigerator car equipped with my refrigeration system. Referring to Figure III it will be noted that Dewar flasks II are fitted into the ends of the car. These Dewar flasks may be for instance, installed in the compartment normally used for ice or may be located in space provided for them in specially built refrigerator cars for use with my process.

In Figure III like parts of those in Figures I and H are given like numerals.

The operation of the unit shown is substantially the same as the operation shown in Figures I and II.

As railroad refrigerator cars are not normally provided with an electric current supply, it is necessary that auxiliary equipment for furnishing the electric energy for the heat unit in the bottom of the liquid air tanks be utilized. Forv this purpose a generator 2| and storage battery 22 are provided. The generator 2| is connected by a belt 23 or other drive means to an axle 24 of one of the trucks of the refrigerator car. The generator will during movement of the car along the tracks supply enough electrical power to heat the heating elements and to charge the storage battery. While in a siding or otherwise stationary on the tracks the storage battery will serve to supply the electrical energy required by the heating elements. An electrical cut-out and voltage regulator unit is included in the wiring system in a known manner to prevent discharge of the battery through the generator when the same is not charging and to prevent overcharging of the storage battery.

Along the inside of the ceiling of the refrigerator car is a trough 25 having apertures 26. The trough 25 is equipped with baffles 21 which serve to prevent the surging of any liquid air which may collect in the trough. Fins 28 may be provided on the outer surface of the trough to increase the heat absorption surface.

The details of the trough construction can be readily seen from Figure IV and Figure VI.

The details of operation of the process as shown applied to a railroad refrigerator car will be obvious tov those skilled in the art from the foregoing description of the process as applied to a household refrigerator.

It should be noted that the neck of the Dewar flask is of such size that there is considerable space between the eduction pipe H and the neck wall. Through this annular space any vapors generated within the Dewar flask can readily escape, and the creation of any superatmospheric pressure within the Dewar flask is avoided. A

superatmospheric pressure in the Dewar flask is' not necessary to remove liquid air as by means of the vapor lift provided the liquid air can be readily force from the Dewar flask with the application of'a very small amount of heat at the lower end of the eduction pipe H,

I may provide other means of supplying heat to the lower end of the eduction pipe. For exg5 ample, a highly heat-conductive metal rod passing through the wall of the Dewar flask and heated at its external end by a thermostatically controlled gas flame may be utilized.

Other means of supplying heat at the location so desired such as by means of a coiled pipe through struction, heavily on Where the system which a heating fluid is source will beapparent.

Instead of using a Dewar flask type of liquid air container, a container of single wall coninsulated with asbestos, magnesite or other suitable well known insulating material could possibly be used. However I prefer to employ Dewar flask type of containers because of their high efliciency.

is applied to a railroad refrigerator car refilling of the containers of liquid air can be readily accomplished by passing a hose into the neck of each Dewar flask. Access to the Dewar flasks can be had by means of hatches 29 passed from an outside located in the roof of the refrigerator car directly above each flask.

While the refrigerator system has been shown as applied to household and railroad car use, it will be understood that the system may be applied to other stationary and mobile refrigeration units. a

For example, the system can be applied to refrigerated storage plants, warehouses, cold rooms, quick freeze compartments and the like. The system can also be applied to motor transports such as meat delivery trucks and airplanes carrying perishable cargoes.

The system can moreover be applied to air conditioning units wherein a supply of cold air is required.

Among the numerous advantages of my invention, I would particularly draw'attention to the advantage that no superatmospheric pressure is created on the liquid air in the container. As is well known, air in its liquid state will quickly and violently change into a gas upon heat being applied to it. While the necessary heat can be kept from reaching the liquid air (at approximately -3l5 F.) by means of a highly heat insulated container such 'as a Dewar flask, there is always the possibility of sufficient heat being supplied by accident or otherwise to cause a rapid change of liquid air to the gaseous state. As a consequence of such heat addition, if the liquid air container were a closed vessel, pressure suflicient to cause a violent bursting of the container walls would result. For this reason I favor the use of a liquid air container having an open neck for the carrying off of any vapor generated from the surface of the liquid air. My system of removing liquid air by an air lift avoids any necessity of using a superatmospheric pressure to force liquid air from the container.

Another advantage of my system is that any increased refrigeration desired is quickly supplied as upon heat being applied to the bottom of the eduction pipe air bubbles are rapidly generated andat once elevate liquid air into the evaporating pan or trough in the refrigerating compartments to effect refrigeration.

I claim as my invention:

1. A process of refrigeration comprising conducting liquid air in controlled amounts into the interior of a heat insulated compartment and forming a pool of said liquid air in the upper part of said insulated compartment effecting vaporization of the liquid air from said pool in the upper part ofsaid insulated compartment by means of the heat contained in said compartment, and,

conducting the vaporized liquid air over the contents of said compartment.

2. A process of refrigeration comprising supplying heat in controlled amounts to the bottom portion of an open, heat insulated container for liquid air, conducting the bubbles of vapor generated through an eduction pipe whereby an amount of unvaporized liquid air is elevated and removed from the container, introducing the liquid air and vapor into the upper portion of a heat insulated compartment, and effecting free vaporization of the liquid air in said compartment whereby refrigeration of the contents of said compartment is effected.

3. A process of refrigeration comprising supplying heat toliquid air near the bottom oi an open, heat insulated container for the liquid air, conducting the bubbles of vapor generated through an eduction pipe whereby an amount of unvaporized liquid air is elevated and removed from the container, introducing the liquid air tion of the liquid air in said compartment whereby refrigeration of the contents of said compartment is effected and controlling the heat supplied to said liquid air in said insulated container by the temperature existing in said insulated compartment.

4. Apparatus for using liquid air as a refrigerant comprising a heat insulated refrigeration compartment, an open, heat insulated container for liquid air, an eduction pipe extending into said container, a heating element positioned at the lower end of said eduction pipe, a conduit attached to the upper end of said eduction pipe all extending into the storage space of said compartment, an evaporating pan connected to said conduit and a thermostatic control in said refrigerating compartment connected to said heating element and to a source of electric current.

5. Apparatus for using liquid air as a refrigerant comprising an' insulated refrigerator compartment, an open container for liquid air in said compartment, an eduction pipe extending into said container, a heating element positioned at the lower end of said eduction pipe, a conduit attached to the upper end of said eduction pipe and extending into the upper portion of said refrigerator compartment, an evaporating pan connected to, said conduit, and control means for said'heating element responsive to the temperature existing in said refrigerator compartment.

6. A process of refrigeration comprising supplying heat in controlled amounts to the bottom of an open, heat insulated container for liquid air, conducting the bubbles of vapor generated through an eduction pipe whereby an amount of unvaporized liquid air is elevated and removed from the container, introducing and discharging the liquid air and vapor into a heat insulated compartment, andeffecting free vaporization of the liquid air in said compartment whereby refrigeration of the contents of said compartment is effected.

'7. The process according to claim 6 wherein the liquid air introduced into the refrigerated compartment is maintained as a pool within an- REFERENCES CITED The following references are of record in the file of this patent: V

UNITED STATES PATENTS Number Name Date 966,076 Bobrick Aug. 2. 1910 2,309,938 Diserens et a1. Feb. I, 1948