US1705928A - Method of and apparatus for preventing the condensation of moisture on the exterior surface of refrigerator cabinets - Google Patents

Description

March 19,' 1929. Y

METHOD OF AND APPARATUS FOR PREVENTING THE CONDENSATION OFv MOISTURE ON THE EXTERIOR SURFACE OF REFRI'GERATOR CABINETS mal IIIHIIHIHIIHW- w/T/VESS March 19, '1929. Y y' .f A, L, LAMBER'I" 1,705,928 l METHOD 0F AND APPARATUS FOR PREVENTING THE coNDENsATIoN oF MOISTURE on THE EXTERIOR SURFACE 0F REFRIGERATOR cABINETs Filed lay 20. 1927 2 Sheets- Sheet 2 6 .5 B30 J4 .I7 97 'si Y'fa 'f/ J6 A l! l w/TA/Ess .Bf m4, A w17* OHNEY Patented Mar. 19,` 1929. l

UNITED STATES PATENT o1=1=1cE.v` ALBERT L. LAMEERT, OF NARBERTH BOROGH, PENNSYLVANIA, ASSIGNOR TO HEINTZ l MANUFACTURINGCOMPANY, A CORPORATION OF PENNSYLVANIA. v

I METHOD F APPARATUS FOR PBEVENTING' THE CONDENSATION OF MOISTURE ON THE EXTERIOR SURFACE OF REFRGERATOR CABINETS.

Application led May20, 1927. Serial No. 192,861. e

It is Well known that asthe temperature within 'a refrigerator is considerably below that of the surrounding atmosphere, there is a continual transfer' `of heat from the walls 5 of the refrigerator to the interior thereof, with the result that the walls are reduced in temperature and maintained below that of the surrounding atmosphere. lVhen the outer surface of the refrigerator cab-inet is lowl0 ered in temperature to or below. the dewpoint temperature of thev surrounding at` mosphere the latter becomes more or less dehydrated through the condensation and deposit of moisture or dew on the relat1vely cool surface.

The condensed moisture collected on the outer surface of the cabinet is unsightly and obviously objectionable in theuse ofzthe refrigerator. As it accumulates it runs down the outer surface of the cabinet and drips upon the floor, rendering the lattercontinually damp and sometimes maintaining a pool there, which is, of course, unsanitary and untidy and tends to rot the/Hoor as time goes on. Furthermore, tlie condensation injures the finish applied to the exterlor of the cabinet and not only mars its appearance, but tends t'o warp or rot the wall if the outer surfacev is of wood or other material similarly aected by moisture, or to cause it to rust if iliade of metal. A. I

The amount of'such condensation per unit of area depends upon the atmospheric condition and upon the temperature of the outer surface of the-cabinet due tothe transfer or leakage of heat from the walls of the cabinet-'to'- the interior of lthe refrigerator, the latter factor being in turn dependent (disregarding the so-called skin effect and possible heat losses through radiation) upon the difference in temperature between the interior of the refrigerator and the surrounding atmosphere' and upon the thermal conductivity of or rate -of/ heat transfer' through the refrigerator walls. y As to the atmospheric.condition both hu- `midity and temperature are important. The higher the humidity the relatively higher the dew-point, and the more readily the condensation forms lsince less heat transfer Y through the walls will reduce the temperature ofl the outer surface lof the cabinet to the dew-point. .A higher percentage of humidity also renders the condensation more profuso. On the other hand, a higher atmospheric temperature ives a higher saturation point, making possi le a larger proportion of aqueous vapor in the air. A relatively hlgh temperature also increases the usual temperature difference between the atmosphere and the interiorof the refrigerator y within the refrigerators than ice does, and

hence their introduction has increased the tendency toward the formation of condensatlon on the exterior of the cabinets and has rendered the4 problem more acute.

The thermal conductivity of refrigerator walls varies, of course, according to the material or materials of which they are constructed and the thickness thereof. But in every mstancethereis necessarily some heat.

transfer through the walls as perfect insulation is impossible. Furthermore, there are vpractical'difficulties in obtaining the maximum insulating efficiency, particularly in refrigerators of the domestic type, since the element of expense limits both the character 'and the thickness of the insulating materials which can be used in producing a saleable article, and furthermore, since the walls can-- not be too thick without eitherencroaching unduly on the space required for refrigerating purposes or else rendering,thepcabinet too bulky and cumbersome. Where the wallsl are constructed, as in ordinary cabinets, with their outer surfaces of wood, the objectionable condensation forms under certain of the above mentioned conditions, but wherey the outer surfaces are of metalas in the modern cabinets the condensation has been found to be particularly troublesome.y

These Various factors or conditions enter- :ing into the formation of the condensation cannot be controlled or eliminated as a practical means ofeffecting a solution of the problem.

An object ofthe resentinvention is to l provide a method of effectively preventing 5 the formation of such condensation on the exterior surface of a refrigerator cabinet Inotwithstanding the existence of the aforesaid factors or conditions and the degree in which the are present, and without inter vfering wity the efficiency of the refrigerator,

yas well as on the stationary walls thereof.

A further object'jof the invention is to provide an apparatus for carryingout this process which yoperates positively and auto- Y matically and without adjustment or atten- 't1on, which 1s simple 1n construction, has no moving parts, and is not likely to get out of order, and`which adds but little to the cost of the usual 'refrigerator structure.

With-these and other objects in View, the

.2K5 invention comprises the several stepslv and the relation thereof to each other which will be exemplified in the hereinafter disclosed method, and the Ifeatures of construction, combinations of` elements and arrangements 30 of parts which will be exemplified, in the ap aratus hereinafter set forth.

eferring to the accompanying drawings in which similar reference numeralsindicate f similar parts throughout the several views- Fig. l. isa diagrammatic view illustrating the operation of my method for preventing the condensation of moisture on e exterior walls of the refrigerator cabinet;

Fig.l 2 1s a transverse vertical section of @D one embodiment of a refrigerator cabinet for carrying 'outthe process above referred to, the section being talren 4on the line of 2 2 of Fig. a; 1

Fig. 3 is a horizontal'section thereof, the

section being taken on` the line'o'f 3-3 of Fig. it; v

- Fig 4l is a vertical section fromfront to rear, the section being taken `on the line of 4-4 of Fig. 2; i

0 7 Fig. 5 is a snnilar view taken on vthe line of 5 5 oflig 4f; and p p f Fig. @isan enlarged sectionalViewv show v lng the doorky structure. f

tion and deposit of moisture or. dew 9 on the exterior surface' of thel wall .of a refrig- -erator cabinet, l create .and maintain within, and in spaced relation to, such wall,l a .zone

' 60 of temperature at or below the, dew-point of the normal atmos here outside of, or surrounding, the cabmet. Such zone may be formed, for instance, by the wall of an i `innerrefrigerating compartment, which is @6.5 cooled by'any suitable refrlgerating (means and the temperature of which, is usually maintained below the dew-point of the nor- -mal atmosphere outside of the cabinet. l. admit air from the outside atmosphere to the inner side of the cabinet wall to fornrand maintain al layer of air which covers the inner surface thereof, and which is interaA certain lowering of the temperature of.

lthe layer, increase its density and cause it to descend, sweep downwardlyover the inner surface of the cabinet wall and pass at its lower end into the outside atmosphere, while additional volumes of air are simultaneously drawn in from the outsidel atmosphere at 'and follow (the upper end of the descending layer. As the layer passes downwardly along the zone of lower temperature it is cooled thereby Vmore and more, until it finally escapes.

I regulate the passage of the layer of air` into the, outside atmosphere so that it es-4 capes before becoming lowered in tempera.

ture 'to the point of reducing,`-by carrying off heat from the wall of the cabinet,the temperature of the outer surface of the cabinet wall to the dew-point of the-outside atmosphere. rihis is an important step iny the process and is effected by suitably. roportioningl the thickness of the layer o air ieu to the height of vthezone of relatively low temperature along which it travels, and also to the heat transfer from the layer to .the

zone, which latter factor is dependent, when l the zone is inthe form of a wall of an inner refrigerating compartment, upon thethermal conductivity ofsuch wall, and upon the difference between the normalI temperature llO of the layer as'itris admitted from the outside atmosphere, and the temperature within the inner refrigeratmg compartment. he

height of the wall of the inner refrigeratingr compartment and' also the thermal conductivity thereof can, of course, readily be determined. However, there may be consid- 1 erable. variation from time to time in the i, lin carrymg out `the present embodiment 5 5 ofmy methodof preventing the'condensaf normal temperature of the layer of 'air (which corresponds with the temperature of the outside atmosphere), and\-th`e temperature maintained within the inner refrigerating compartment- By taking` the probable' -,of the theory of operationof this method, itV

-is believed that the portion of the layer of air coming in contact with the zone as the air is admitted from the outside atmosphere, is lowered in temperature and 'forms a stratum which is cooler than the stratum in f contact with the inner surface of the cabinet wall. The cooler stratum descends by reason ofits increased density and as it flows downwardly along and in Contact with the zone is cooledthereby more and more and becomes gradually thicker and flares downwardly andv outwardly, while the warmer ystratum is correspondingly, gradually reduced in` thickness and tapers from the upper and to the lower end of the layer.

lVhile there vmay be no actual sharp line of division between rthe two strata, ythey may be considered as divided, atleast theoretically,valong a plane extending obliquely between the zone and the cabinet wall and in' togetherat the lo/wer end of the layer intol the outside atmosphere. By 'suitably-pra portioning the thickness of the layer, as hereinabove described, the plane of division will pass from end to end of'. the layer without touching the cabinet wall, and the inner surface of the cabinet -wall will be at all times entirely covered by the warmer stratum of the layer of air, the temperature of which stratum is substantially the same asr the outside atmosphere. Under these circumstances .there is little, if any, heat transfer from the cabinet wall to the layer, andtherefore the lowering of the temperature of theouter surface of the cabinet wall to the dew-point of the outside atniosphcre is avoided and the formation of condensation thereon is effectively prevented.

Of course, itis not desired to have 111e, layer of' air any thicker than necessary since that involves either adding to the bulk of the cabinet or encroachiug on the available space therein, and might also interfere with the drawing of the warmer stratum downwardly with the cooler stratum the latter de scends. But even if the layer is reduced in thickness so that the plane of division between the strata intersect-s the cabinet wall and the cooler stratum comes in contact with the inner surface thereof, the `method is nevertheless operative so long asthe layer "descends and escapes into the outside atmosphere before any portion thereof in contact with the inner surface of the cabinet wall to the point of reducing,-by carrying off heat from the wall,-the temperature of the outer surface of the cabinet wall to the dew-point of the outside atmosphere.

It will be apparent that this method may be employed in connection with the respective walls of'a refrigerator cabinet, partielllai-ly the upright walls, and with the door or movable wall as well as with the stations ary walls thereof, that it will prevent condensation on the exterior surface of the cabinet notwithstanding the existence of' the becomes lowered in temperature by the zone beforeinentioned factors and conditions entering into its formation, and that the operation of the method will inno wiseinterfere with the efficiency of the refrigerator.

Referring to the present embodiment of the' apparatus for carrying out my method, the re rigerator cabinet comprises an exterior casing 1 and an inner refrigerating compartment 2 mounted therein as hereinafter pointed out.

The casing is preferably, although not necessaril made of heavy sheet. metal, the outer surface of 'which is painted, lacquered, enameled or otherwise given an attractive finish. It has aback wall 3, side walls 4, and a top wall 5, the front being open. ,The side and top walls maybe formed from one piece of metalwith flanges 6 along their Arear edges to which the back wall 3 is rigidly secured, as by screws or rivets 7.

A pan Sis arranged within and extends across the casing below the refrigerating compartment 2, and is suitably fastened,- as at 9, to the back wall 3 and .side walls 4. A drain pipe l() may lead from the pan and in the present instance is shown as passing outwardly through the back wall 3, the bottom of the pan being inclined toward the drain, so as to cause any -water collecting in the pan to pass off' therethrough.

The casing preferably extends downwardly below the pan to provide a compartment 1l beneath the same for housing the mechanical unit (not shown) employed when the refrigerator is cooled mechanically. In such instance a bottom 12 for .this coiiipartn'ient is secured across the lower end of the casing.

A frame of'wood or other suitable material is mounted within the open front of thel casing and comprises sides 13 extending substantially the full height of' the casing, aii upper cross-bar or top 14, and a lower crossbar 1 5 located above but adjacent to the pan-8. The upper cross-bar 14 of this frame is secured by screws 16 or the like to a facing 17 which depends from the top wall 5, turns inwardly beneath the cross-bar and substan` tially conceals the latter from View. The sides 13 are secured, as at 18, to similar facngs 19 extending laterally and inwardly from the side walls 4 of the cabinet. A facing covers the front surface of the lower cross-bar 15 and extends downwardly therefrom and is turned rearwardly under` and supports the front of the pan 8.

-The inner refrigerating compartment 2 is box-like in form, is open at its front, and is supported by, and suitably secured along its front edges to, the frame. `While this compartment may be of any appropriate construction, it consists in the present instance of nested, metallic shells 21 and22, with suitable insulating material 23 interposed therebetween, the -shells being fastened, as at 24, to the -sides 13 and upper and lower cross bars 14 and 15 of the frame. The bottom of the compartment is valso supported upon and in spaced relation to the pan 8 by means of a plurality of inter osed blocks 25 arranged so as not to inter ere with the free drainage of the pan to the pipe 10. A. chamber 26 is thus provided between the' compartment and the pan.

The compartment 2 is otherwise spaced yfrom the casing 1 so as to provide intervening air chambers 27 between back and sides of the compartment, and the corresponding back wall 3 and side walls Ll, and an upper air chamber 28 between the top of the compartment and the top wall 5. The chambers 27 communicate attheir upper ends with the chamber 28 and at their lower ends with the chamber 26.

Openings or louvres 29 are formed in the back wall 3v and the side walls Y4c adjacent the upper and lower ends, respectively, of

the chambers 27, whereby to admit air freely fromthe outside atmosphere and permit itl to circulateI therethrough. There may be one or a plurality of openings or louvres 29 at each end, but in either instance they extend across the correspondingwall ofv the casing for substantially the full width thereof and their total area is preferably approximately equal to the cross-sectional -area ofthe adjacent lchamber 27 and ,to the total area of the openings or louvres at the opposite end of such chamber.

To-admit air from the outside atmosphere' to the upper chamber 28, oneor more openings 30'are formed in the top wall 5 substantially centrally thereof. In connection with this chamber 28 it is to be noted that'the top of the refrigerating compartment 2 is inclined downwardly from -front to rear (as shown in Fig. 4) for a purpose to be hereinafter pointed out.

Mounted on the frame at the front of the refrigerator cabinet is a door consisting of an inner wall 31 and an outer wall 32, the former being heat insulated as indicated at 33 and Vbeing adapted to close snugly against a suitable seat -or gasket 34 surrounding the doorway. The outer wall 32 has a suitable nish a plied to its outersurface and is supporte 1n spaced relation to the inner wall 31 so as to provide one or more intervening air chambers 35. In the present instancethe su porting means consists of a plurality o vertically disposed spacing strips 36, two of which are interposed between the walls adjacent the side edges thereof, and another ofwhich located intermediately of these two. Two chambers 35 are thus provided and' are similarly opentop and bottom to 'admit air from the outside atmosphere and permit it to circulate therethrough.

Adjacent the lower ends of the chambers 35 and beneath the outer surface of the inner Wall 31, is a trough or gutter 37 extending alone' and carried by the lower crossbar 15 ofa the frame. This trough drains to ,an outletpipe or spout 38 vwhich passes through the cross-bar 15 and discharges into the pan 8.

A cooling `element 39 is contained within the refrigerating compartment 2 and lowers the temperature therein and usually maintairts the same below the dew-point. of the normal outside atmosphere. Thiselement may be in the form of the usual brine tank or other cooling unit of a mechanical cooling system, or in the form of ice.

In the operation of the apparatus, the

layers or columns of air within the respective chambers 27 normally descend therein through the cooling action lof the corresponding walls of the refrigerating chamber 2 and continually pass into the-outside atmosphere through the lower.i openings or louvres 29, while additional Volumes of air are simultaneously drawn int-o the chambers through the upper openings or louvres 29. By having the total areas of the upper and lower louvres of each chamber substantially equal to each other and to the crosssectional area of such chamber thecirculation of air is free and unobstructed, and by having the openings or louvres 29 extend transversely for substantially the full width of the wall of the casing the circulation Will be substantially 4uniform across the full width of each chamber. O11 account of the communication between each of the chambers 27 and the upper air chamber 28 the` descending layers o air inthe former also serve to draw the layer of air downwardly from the latter and cause air from the outside `atmosphere to be simultaneously ad- .mited through the openings 30 in thev top wa l 5.

various air chambers is-determined by the spacing between the outer casing and the inner refrigerating compartment, and is ulate the passage of the layers of air into the The thickness of the layers of air in these outside atmosphere so that they escapebe'- A fore becoming lowered in temperature by contact with the walls of the inner refrigerating compartment to the point of' reducing,-by carrying off heat from the walls of the vcasing,--the temperature of the outer. surface of the casing to the dew-'point of the outside atmosphere. The samejaction takes place in connection with the air chambers 35 located between the inner land outer walls of the door. As a result, the condensation of moisture or dew on the exterior surface of the casing is effectively prevented, and this applies to the door kas well asto'the station-y ary walls.

Any condensation vthat does form occurs on the outer surface of the walls ofthe inner refrigerating compartment and the outer surface of the inner wall of the door, all of which are hidden from view and are not required to take' an attractive'iinish and hence may be suitably constructed or treated to withstand moisture,-without detracting.

from the :appearance of the refrigerator Moreover, such condensation collecting on the side and back walls of the re'- frigerating chamber runs ldown -the same into thev chamber 26`below `the refrigerating.

compartment and is received in the pan 8, from which it is discharged through thev drain-pipe l0. Moisture condensed on the top wall of the refrigerating lcompartment will flow rearwardly by virtue of the inclined disposition thereof, above pointed out, and hencewill run 'down the rear wall of the compartment into the pan.` The trough or vgutter 37 receives the condensed moisture which dri s from the outer surface of the inner wall o the doorand carries the same off through the pipe 38 to the pan.

It is to be noted that none of the air chambers are in communication with the interior of the refrigerating compartment and -that the admissionv of air thereto from the outside atmosphere and its circulation thereu' through in no wise interferes with the efiir 'ciency of thc refrigerator; the apparatus opcrates positively and automatically, 'and without adjustment or attention, is simple in construction, has no moving parts, and is not likely to get out of order,and involves but little addition to the cost of the usual refrigerator structure.

lVhile in the present embodiment of the apparatus chambers surround the inner'refrigerating compartment on all sides, the chamber at the top of the cabinet may be omitted,'as well as one or more of the other chambers if not required in a given instance. Where a mechanical unit is not employed-in cooling the refrigerator, the compartment therefor in the lower portion of the cabinet may be used for general storage purposes or omitted altogether.

Furthermore, it is to be understood that the location and arrangement of the openings or louvres may be varied, that the drain may be omitted, and that various other changes may be made in the method and -apparatus herein disclosed without departing from the spirit of the invention as defined in the appended claims.

Having thus described my invention, I claim and desire to protect by Letters Patent of the United States- 1. The method of preventing condensation on the exterior surface of the wall of a refrigerator cabinet, which consists in causing a layer of air from the outside atmosphere to sweep downwardly across the inner surface of the wall by exposing the layer to. a zone of lower temperature within the wall, and causing the layer to pass into the outside atmosphere beforey becoming lowered in temperature to the point of. reducing, by carrying off heat from the wall, the temperature of the outer surface of the wall to thel `dew-point of the outside atmosphere.

2. The method of preventing'condensation on the exterior surface of the .wall of a refrigerator cabinet, which consists in admitting air from the outside atmosphere to 'form a' layer covering the inner surface of the wall and in free communication adjacent its upper and lower ends with the outside atmosphere, cooling such layer from the side thereof remote from the wall and' therebycausing the layer to descend and pass into the outside atmosphere at its lower end and simultaneouslyvdraw in additional volumes of air at its upper end, and causing the layer of air to pass into the atmosphel'e before the 100 portion thereof in contact with the wall becomes lowered to the dew-point temperature of the outside atmosphere.

3. The method of preventing condensation on th'e exterior surface of the wall of a re- 105 mosphere to follow the upper end of the descending layer, and causing the descending layer to pass into the outslde atmosphere at its lower end before the portion of the layer in contact vwith the inner surface of the wall is cooled to the dew-point of the outside atmosphere.

4. The method of preventing condensation on the exterior surface of' a refrigerator cabinet, which consists in causing a layer 125 of air to be interposed between the wall of `an inner refrigerating compartment and the wall of a surrounding casing and in free `communication vadjacent its top and bottom with the .outside atmosphere, cooling the layer of air by contact with the wall of the refrigerating compartment and thereby causing the layer to descend and drawin additional volumes of air from the outside atmosphere to follow the upper end of the descending layer, and causing the descending layer to pass at its lower end into the outside atmosphere before becoming lowered in temperature to the point of reducing, by carrying off heat `from the casing wall, the temperature of the outer-surface of such wlzill to the dew-point of the outside atmosere. v

l- 5. In a device of the character described, the combination of inner and outer walls y spaced apart with an intervening air chamber, the chamber having vertically spaced openings leading therefrom and communicating with the outside atmosphere, and

refrigerating means within 'the inner wall cooling the same to or below the dew-point temperature of the outside vatmosphere and thereby causing air from the outside atmosphere normally to circulate continually downwardly through thel chamber, to prevent the condensation of moisture on the exterior of the refrigerator cabinet.

6. In a device of the character described,

for preventing the condensation of moistureon the exterior of a refrigerator cabinet` the combination of inner and outer walls spaced apart wlth an intervening air chamber, the chamber having vertically spaced openings leading'therefrom and Xcommuni- A eating with the outside atmosphere, and

means within the inner wall cooling the same to the dew-point temperature of the outside atmosphere and thereby causing air from the outside atmosphere to circulate downwardly through the chamber, the spacing between said walls bein proportionedE to the distance the air trave s along the inner wall and to the heat transfer from the air to such inner wall. i L v 7. In av device of the character described,

for preventing the condensation of moisturel on the exterior of a refrigerator cabinet, the combination of inner and outer walls spaced apart with an intervening air chamber, the chamber :having vertically spaced openings leading therefrom and communieating with the outside atmosphere, and means within the inner wall cooling the same to the dew-point temperature of the outside atmosphere and thereby. causing air from the outside atmosphere normally to circulate downwardly throu h the chamber,l the areas of said o enings to each ot er and Vto the cross-sectional area of the chamber'. i v c y 8. In a device of the character described, for reventing the condensation of moisture on t e exterior of a refrigerator cabinet, the combination of inner and outer walls spaced apart with an intervening air chamber, the

ltially the full width thereof.

ing substantially equal.

chamber having vertically spaced openings leading therefrom and communicating with the outside atmosphere and means within the inner wall cooling the same to the ldewpoint temperature of the outside atmosphere and thereby causing air from t-he outside atmosphere normally to ,circulate downwardl through the chamber, said openings exten ing across the chamber for substan- 9. In a device'of the character described, for preventing the condensation of moisture on Xthe `exterior of a refrigerator cabinet, the combination of inner and outer walls spaced apart with an intervening air chamber, the chamber having vertically spaced openings leading therefrom and communieating with the outside atmosphere, means within the inner wall for cooling the same to the dew-point temperature of the outside atmosphere and thereby causing air from the outside atmosphere to circulate downwardly through the chamber, and means for collecting moisture condensed` on the outer surface` of the inner Wall.

l0. In adevice of the character described, for preventing the condensation ofmoisture on the exterior of a refrigerator cabinet, the combination of an inner refrigerating compartment, a casing surrounding the same and vproviding an intervening air chamber out loutside atmosphere and thereby causing air from the outside atmosphere normally to circulate downwardly through the air chamber.

11. In a device of the character described, for preventing the condensation of moisture on the exterior of a refrigerator cabinet,

the combination of an inner refrigerating compartment, a casing surrounding the same and providing'an intervening air chamber out of communication with said compartment, said casing being formed .with openings leading from the chamber adjacentthe `upper and lower ends thereof and communieating with the outside atmosphere, means within said compartment for cooling the wall thereof to the dew-point of the `outside atmosphere and thereby causing air from the outside atmosphere to circulate down-v wardly through the air chamber, and means for collecting moisture condensed on lthe outersurface of the wall of the compart- 125 ment. y

12. In a device of the character described,

for preventing the condensation of moisture 'on the exterior of a refrlgerator cabinet, the. comblnation of an mner 4refrigerating 130 compartment, a casing surrounding the same and providing intervening air chambers, and a door comprlslng inner and outer Walls 'spaced apart with an intervening air chamon the exterior of a refrigerator cabinet,`

the combinationof an inner refrigerating compartment, a casing surrounding the same and providing an intervening air chamber, a door comprising 'inner and outerwalls spaced apart with an intervening air chamber, each of said chambers being out of com-I munication with the refrigerating compartment and being formed with vertically spaced openings communicating with the outside atmosphere, and means within the refrigerating compartment for cooling the same to the 'dew-point temperature of the outside atmosphereand thereby causingjair from the outside atmosphere vto vcirculate downwardly through the respective chambers. 4

14.-. In a device of the character described,

for preventing the condensation of moisture on the exterior of a refrigerator cabinet,

the combination of an inner refrigerating compartn'ient, a casing surrounding the same and 'providingan intervening air chamber, a door comprising linner and outer walls spaced apart with an intervening air chamber, each of said chambers being out of communication with the refrigerating compartment and being formed with vertically spaced openings communicating with the outside atmosphere, means within the refrigerating compartment for' cooling the same to the dew-point temperature of the outside atmosphere and thereby causing air from the outside atmosphere to circulate downwardly through the respective chambers, and coml men means for collecting moisture condens-1 ing on *the outer surface of the wall of the compartment and on't-he outer surface of the inner Wall of the door. n

15. In a device of the character described, for preventing condensation on the exterior of a refrigerator cabinet, the combination of a door comprising. inner and outer Walls spaced apart with an intervening air chamber, the chamber having vertically spaced openings communicating with the outside atmosphere, means within the inner wall for cooling the same vto the dew-point temperature of the outside atmosphere and thereby causing air from the outside atmosphere to circulate downwardly through said 'chamber, and means for collecting moisture condensed on the outer surface o? the inner wall.

In testimony whereof, I have signed my name to this specification.

ALBERT I.. LAMBERT.

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