US2541169A - Stand-by refrigeration system - Google Patents

Description

Feb. 13, 1951 J. W. MARTIN 2,541,169

STAND-BY REFRIGERATION SYSTEM Filed Jan. 2o, 1947 l JNVENTOR.

Patented Feb. 13, 1 951 STAND-BY REFRIGERATION SYSTEM James W. Martin, St. Petersburg, Fla., assignor,

by mesne assignments, to The Broquinda Corporation, St. Petersburg, Fla., a corporation of Florida Application January 20, 1947, Serial No. 723,158

2 Claims.

This invention relates to improvements in refrigerating systems as applied to vehicles,

This invention comprises a system of refrigeration for use on mobile refrigerators such as refrigerated trucks, railway cars, LCL (less than carload lots) containers and the like. The invention is concerned with such systems constructed for the use of a solid primary refrigerant such as water ice, solid carbon dioxide ice and the like. Refrigerating systems using such a primary source of refrigeration frequently include a closed liquid circulatory system in which the liquid acts as a secondary refrigerant, circulating between the primary refrigerant and thc space to be refrigerated to abstract the heat from that space and return it to the primary source where it is dissipated` This type of system has found extensive use in mobile refrigerating systems notwithstanding the fact that it is a relatively expensive type of refrigeration in operation because oi the many advantages incident to its use. Because of this high cost of operation efforts have been made to provide a system and method of refrigerating the mobile units during standby periods, for example, during the night when the mobile units are inactive. It is well understood in this art that the usual stationary refrigerating systems as ammonia plants, for example, are relatively inexpensive to operate. It is commonly possible to attain refrigeration at a cost as low as a dollar per ton of refrigeration Whereas refrigeration by solid carbon dioxide costs about twenty dollars per ton of refrigeration.

The main object of this invention, therefore, is to provide a system wherein, during standby periods, such xed sources of mechanical refrigeration are employed to maintain the mobile refrigerator units at the proper low temperatures, with the result that during standby periods the cost of refrigeration is greatly reduced.

A more speciiic object of the invention is to provide a simple mechanism by means of which the refrigerating system with which the mobile refrigerator is equipped is adapted for connection to a xed mechanical refrigerating system.

Other and more detailed objects of the invention will be apparent from the following description of the embodiment thereof illustrated in the attached drawing.

In the accompanying drawing the single gure is a diagrammatic and schematic illustration of the subject matter of this invention showing' some parts in cross section.

A refrigerator truck has been selected for the purpose of illustrating the invention. The truck includes a body It suitably insulated to form a closed space to be refrigerated. This space is refrigerated during the active periods by means of solid carbon dioxide and the like. A container I I, preferably of metal, forms a compartment in which the blocks I5 of solid carbon dioxide are placed so as to rest on the bottom wall oi the container Il in heat conductive relation therewith. Surrounding the container Il in spaced relation with respect thereto is a housing I2 which may be of a heat conducting material without a heat insulating covering or which may be enclosed in a heat insulating covering, not shown, depending on whether or not it is de sired to absorb heat at this point from the space to be refrigerated. The containers II and l2 are nested, as shown, in spaced relation and are connected together at their peripheries to form a iluid tight joint with the result that the closed space i3 results. The inner container I! is open at the top so that the solid carbon dioxide can be charged thereinto. A removable heat insulating cover i4 is provided, equipped if desired,

with some means (not shown) to permit the escape of carbon dioxide gas to the atmosphere.

A heat absorbing coil or plate I6 is provided having connections to the space I3 at the points Il and i 8, as shown. The space within the coil I 6 and the space i3 are lled with a suitable liquid which will circulate by thermosyphonic action from the space i3 to and through the coil it and back to the space I 3. The liquid in the space I3 will be cooled 4by conductive heat ex change with the ice I5 through the conductive wall II. The cool liquid will move to the bottom of the space t3 and enter the coil I6 at its inlet Il. As it moves through the coil it absorbs heat from the space being refrigerated and in heated condition is discharged from the coil I6 through its exit end I8 into the space I3. Thus by natural circulation the liquid secondary refrigerant absorbs heat in the space being refrigerated and carries it to the primary refrigerant where it does work in subliming it or melting it.

This part `of the system will be recognized by those skilled in the art as one well known type or" refrigerating system now in common use in various forms.

In the operation of a system of this type as previously mentioned, it costs about twenty dollars per ton of refrigeration to maintain the refrigerated space suitable for the storage and transportation of perishable food products. The

3 refrigerated vehicles are commonly inactive for a large portion of each day and therefore any system which would make it possible to keep the refrigerated space at a safe low temperature during these periods at a lower cost would be of considerable utility. As the cost ot refrigeration by means of fixed mechanical refrigerating systems isrelatively much lower, the use of such systems during the inactive periods of the vehicle would be desirable. The warehouse or distributing point from which. such vehicles are dispatched being the main storage point for Vthe perishable products to be transported are commonly equipped with mechanical refrigerating apparatus. In accordance with this invention, advantage is taken of all these factors.

As illustrated in the drawing, the cooling. coil ifi is provided with a cooling coil i9 concentric therewith, the ends 2li and 22 of which extend exteriorly of the coil l and are provided with thef valves 2l' and 23 respectively. At 25 is d-iagrammaticaflly illustrated any available source' of linedY refrigeration. This system, for example,

may be an ammonia plant or other common type of mechanical refrigerating plant. Illustrated in the drawings at 2li and 25 are any suitable aa for example, ii'exible pipes by means ci wh" +he ammonia circulatory system of the refrigerating source 2S can be attached to ends and E?. of the inner coili9.

When the truck` 59 returns to the warehouse to sta-nd by until morning the sourcel 2S is connected. to the coil I9 and valves 2! and 23 are opened; With the source in operation', refrigerated ammonia at the proper temperature is caused to circulate in the coil i9. By heat transfer through the wall of the coil lllthe secondaryy refrigerant in the coil l is set in circulatory movement that is, convection ourrents are set up inplanes substantially at right to the length of the coil l. It is' obvious thinere that the secondary refrigerant in the coil lt-'absorbs heat from the space of the body Hl and' transfers it to the ammonia inthe coil i9. Thus, by-this simple mechanism the refrigerationof the apparatus lil is taken over by the mechanical refrigerating source. An im.- proyed and' unobvious advantage of this system is that the secondary refrigerant in the coil I6 does not move into, through and from the space l3 but takes place, as explained, in planes at right angles to the coil l5. The resultY is that the solid carbon dioxide I5 does not do any work and therefore in a large measure is preserved: for use the next day when the vehicle goes bacia into active use. Only soy much refrig eration; is lost by the solid carbon dioxide as is represented by the leakage of heat to it. The stationary secondary refrigerant inthe space l3- acts as an insulating layer and ifthe outer container l2 isenclosed within an insulating covering the blocks l5 are reasonably Well protected against the entry of heat. Thus, the combination herein disclosed acts simultaneously to pro-vide standby refrigeration at relatively low cost and by its peculiar manner of functioning short circuits the circulatory system of which the coil i6 is a part so that'the solid carbon dioxide is preserved for future use.

It will be apparent to those skilled in the art that the subject matter of this invention has been disclosed in its broad outline without special reference to detailed mechanical features which would naturally be used in applying this subject matter to an actual installation. The connection of the source i6 to the coil I9 can be greatly facilitated by the'- use of suitable coupling devices which permit connecting up and disconnecting the parts quickly. It is likewise apparent that Vsuitable forms of automatic thermostatic control and other common accessories can be used. I

do nottherefore desire tobe limited tothel system as illustratedr but only as required by the appended claims.

What is` claimed is:

1. In.1 a refrigerating system for a heat.Y insulated housing, a closed circulatory liquid containing systemin said housing including a. receptacle for ice; a chamber about said receptacle connected 4to the ends of. said system at vertically spaced points whereby' the liquid moves longitudinally thereof under thermosyphonic action to refrigerate thel interior of said housing, a con'- duit immersed in thev liquid in said system and means for circulating a reirigerating fluid through said conduit.

2. An apparatus for effecting standby refrigeration of a mobile refrigerating unit having a heat insulated housing forming the compartment to be refrigerated, comprising a liquid containing cooling coil in said housing including a receptaclev for ice for cooling said liquid by conductive heat exchange and a cooling coil within and immersed in the liquid of said rstcooling coil and adapted tobe connectedv to an external source of refrigeration.

JAMES W. MARTIN.

REFERENCES CITED The followingv references are of record in the file of this patent:

.UNITED STATES PATENTS Y Number Name Date 870,913 Trowbridge Nov. 12, 1-907 2,007,288 Thomson J-uly 9, 1935 2,016,377 Krotzer Oct; 8, 1935A 2,187,569 Henney Jan. 16',y 1940 2,214,055v Henney Sept. 10, 1940 2,310,657 Shively- Feb. 9, 1943V 21,315,460 Steenstrup Mar. 30,- 1943 2,450,713 Brunsing Oct. 5, 1948

Images