US2874554A - Refrigerating transport - Google Patents

Description

' T. M. ELFVING ETAL REFRIGERATING TRANSPORT Feb. 24, 1959 3 Sheets-Sheet 1- Filed March 22, 1954 1 INVENTORS THOQE M ELFV/NG m BY EARL 1/. HOPK/NS 5 $4 a #4 4 tau...

,4770PA/EVJ 1959 jr. M. ELFVING ETAL 2,874,554

,REFRIGERATING TRANSPORT 3 Sheets-Sheet 2 Filed March 22, 1954 INVENTORS THORE M ELF l/l/VG EARL 1/ HOPK/NS Waa $42,...

REFRIGERATING TRANSPORT Thore M. Eifving, San Mateo, and Earl v. Hopkins, San Carlos, Calif.

Application March 22, 1954, Serial No. 417,850

' V 4 Claims. or. 61-405 This invention relates to and in general has for its object the provision in a refrigerator car or other transport of a completely sealed inner air circulation envelope surrounding the cargo compartment and in closed circuit with the cooling coils of a mechanical refrigerator.

A further object of this invention is the provision of a refrigerator car of the character above described and wherein the said inner envelope is surrounded by an outer insulating envelope separated from the inner'envelope by a common air-tightbut moisture permeable wall or mem brane. j

Still another object of this invention is the provision in a refrigerator car of the character described of car doors having portions thereof in good heat transfer relation with the peripheral edges of the inner envelope which.

define the car door openings.

As is well vknown to the industry, once comestibles are frozen for storage and/or transportation, they should be maintained within a limited temperature range of 3 or 4 degrees to avoid deterioration, such as change in flavor and the like. This is true irrespective of the actual temperatures used, that is, whether the comestibles'are frozen at or atany other temperature.

' Currently, whe nmechanically refregerated cars are used for transporting frozen comestibles,the cooling coils of refrigerating units have to be defrosted about every eight hours, since at times "they are in open communication with the cargocompartment and sometimes even with the external atmosphere, and a substantial quantityof moisture condenses thereon. v

To defrost, the unit considerable heat has to be-added thereto, heaters being provided for this purpose. This in turn means that to avoid a drop in temperature of the cargo during defrosting periods, the refrigerating units must be of sufficient capacity not only to take care of' normal operating conidtions but also to compensate for the heat added to the system during the'defros'ting periods;

More specifically, one of the objects of this invention is the provision of a refrigerating unit wherein thecommodity space is defined and enveloped by an inner flue,-,

passageway or envelope through which refrigerated air can be circulated, wherein said inner flue is in turn enveloped by an outer insulating chamber or" envelope, wherein the outer walls of both of said envelopes are airand moisture-tighnand wherein the common inter s with each ,otherthereby forming, a continuousjinner en-j MIC . a ings, one form of the invention is shown, but it is to be understood that it is not limited'to such form, since the invention as set forth in the claims may be embodied in.

other forms.

Referring to the drawings:

Fig. 1 is a longitudinal, mid-vertical section taken through a refrigerator car embodying the objects. of my invention. 7

Fig. 2 is a transverse section taken on the section line 2-2 of Fig. l. ,7

Fig. 3 is afragmentary section taken on the section line 33 of Fig. 1.

Fig. 4 is. a transverse section taken on the section line 4-4 of Fig. 1. V

Fig. 5 is a transverse wall section taken on the section line 55of Fig. 4.

As illustrated in these figures, a refrigerator car generally designated by the reference letter A and embodying the objects of my invention is mounted on a steel fabricated bed of conventional construction, generally designated by the reference letter B, and in turn mounted on conventional trucks generally designated by the reference letter C.

Mounted on the bed B is a sub-flooring 1 of sheet metal or waterproof plywood covered on its upper side with a waterand vapor-proof barrier or sheathing 2 such as a layer or coating of asphalt or plastic.

Supported on top of the sheathing 2 and secured to the sub-flooring 1 isa lower set of longitudinally extending beams or stringers 3 and accommodated within each channel or compartment 3a formed by each adjacent pair of stringers is a layer or body ofinsulating material 4 such as glass or slag wool. Extending over and across the stringers 3 is a vapor-permeable, air-tight membrane 5 conveniently made of'pressed wood, hardboard or porous Masonite board. Secured to and supported by this structure is an upper set of transversely spaced longitudinally extending beams or stringers 6 provided along 'lower set of stringers 3 define contiguous non-intercommunicating transversely extending'dead air chambers 11 sealed on their lower sides against the ingress of both air and vapor and together constituting an outer deadair envelope, that the upper set of stringers 6 define contiguous'and intercommunicating, longitudinally extending air passageways or channels 12, sealed on their lower sides against theingress of air from the dead air chambers 11 but in vapor communication therewith, closed at their upper sides by an airand vapor-tight membrane, and together constituting an inner envelope through which air can be circulated.

' Functionally, the walls defining the sides, ends and roof of the cargo or lading compartment D are identical with the floor just described. Each wall is of composite construction including an outer dead air chamber or envelope sealed on its'outer side against the ingress of air and vapor and a contiguous inner air'passageway orenvelope separated from said dead air chamber or envelope by a commonair-tight but vapor-permeable membrane or barrier,

the inner wall of air passageway or envelope immediately P atented Feb. 24,1959

includes an outer metal sheathing or sheet 14, transversely corrugated in accordance with usual practice and. interiorly water-proofed with a coating of asphalt or plastic. Extending across the inner face of the sheet 14 is membrane 16 of moisture-proof, air-tight paper optlonally covered on its outer surface with metal foil 17 such as aluminum foil or other heat-reflecting material.

Mounted interiorly of the membrane 16 is a body or blanket 18 of insulating material such as glass or slag wool and covering the inner face of the blanket is an air-tight vapor-permeable membrane or sheet 19 of pressed wood, or the like. Spaced from the sheet 19 but mounted in substantial parallelism therewith is a substantially airand vapor-tight sheet 21 of plywood or metal, the two spaced sheets 19 and 21 defining an unobstructed air flue, duct or envelope 22 in direct communication with the floor air duct or passageway 12 and forming a continuation thereof. Here it is to be observed that the corrugations of the sheet 14 form dead air chambers, that the blanket 18 lines the vapor-permeable sheet 19 and that since the sheet 14 is water-proofed, the ingress of moisture to the interior of the structure is precluded although if any moisture is entrained within the blanket 18, it is free under the influence of an. appropriate temperature gradient to travel, through the membrane or sheet 19 into the air flue or envelope 22.

Each of the composite, side walls of. the car exceptat the door openings includes an outer, sheet metal sheath mg 23 interiorly coated with a moisture-proof, air-tight layer 24 of asphalt or plastic material. laterally spaced relationship to and in substantial parallelism with the sheathing 23 is membrane 25 of air,- and vapor-tight paper again optionally exteriorly coated or lined with a sheet 26 of heat reflecting metal foil. Conveniently the membrane 25 is held in spaced relation to the sheathing 23 by fittings 27 secured to the sheathing so. as to define therewith a dead airspace or chamber 28. Supported in engagement with the, membrane 25 is, a

thick insulating layer, sheet or blanket 29 of glass or slagwool and. facing the inner side of the blanket 29 is an air-tight vapor-permeable. membrane or sheet 31 of pressed wood or porous Masonite. Mounted in laterally spaced relation to the sheet 31 is an airand watertight sheet 32 of metal, plywood or the like, the two sheets 31 and 32 defining an air flueor envelope 33 in open-communication with the lefthand end car wall air tflue or envelope 22 and with the air flues, passageways or.- channels 12 extending beneath the main flooring 9. of.

the car.

The roof of the car includes an outer. arched steel sheathing 35, sealed to the car side andend sheathing,

all in accordance with well known practice and interiorlycoated with a layer 36 of asphalt or suitable waterproofing material. Extending across the car isan. air-tight vapor-permeable subceiling 37 conveniently made. of

Sup-

car in parallelism with and" at a level substantially belowthe-level ofthe subceiling 37 is the cargo or ladingcompartrnent ceiling 42 preferably made of sheet aluminum or other moisture-tight material having a high heat -conductivity. As aresult' of this construction it will beseen' that-thesubceiling 37 and ceiling .42 definean air=pas- Mounted in.

sageway, flue or envelope 43 extending across the entire ceiling of the car and in open communication with the car end and side air flues or envelopes 22 and 33. Here it should also be noted that the depth of the ceiling flue or envelope 43 is considerably greater than the width of the end and side flues or envelopes 22 and 33.

The righthand end of the car as viewed in Fig. 1 includes and is closed by the usual corrugated steel plate or sheathing 45 sealed in accordance with standard practice to the car roof, sides and floor. Extending across the righthand end of the car at a point substantially inboard of. the sheathing 45 is a composite insulating and flue forming wall including a steel outer sheet 46 interiorly waterproofed by a coating 47 of asphalt or other suitable material, and sealed to the car flooring, side walls and roof. Mounted adjacent the inner side of the sheet 46 is a blanket 43 of glass or slag wool forming a continuationof the corresponding floor, sides and ceiling blankets 4, 29 and 38 respectively. Facing the blanket 48 is an.

air-tight vapor-permeable barrier or membrane 49 conveniently made of pressed wood, hardboard or porous Masonite. Extending across the car in a plane parallel to but substantially spaced from the membrane 49 is, the righthand end cargo compartment end wall 51 made of airand vapor-tight plywood and sealed to the cargo compartment, flooring, ceiling and side walls and with the membrane 49 and thus forming a combination air flue and refrigerator coil compartment 52 in open communication with the floor, sides and ceiling air flues or envelopes 12, 33 and 43, these latter flues or envelopes,

as previously described, being in open communication with the lefthand end air flue or envelope 22.

Mounted within the chamber 53 defined by them! end sheathing 45 and the steel wall 46 is a motor driven mechanical refrigerator 54, the coils 55 of this unit beingdisposed in the end air flue 52. Located at the upper end of the air flue 52 is a fan or blower 56 driven by the motor of the refrigerating unit 54 through suitable shafts and gears here generally and collectively designated by the reference numeral 57.

Provided in the car floor is a sump 58 and drain outlet 59-for use at such times as the refrigerating unit is being defrosted.

Obviously the refrigerating coils 55 simply serve as a heat exchanger and consequently can be replaced by suitable ice bunkers or other desired heat exchangers.

So far then, a refrigerating unit or system has been described wherein a commodity compartment is completely enveloped by an outer blanket of insulation sealed insofar asis possible against the ingress of an, vapor and heat, but which for various reasons may contain some moisture-laden air. Enveloped by this insulating blanket is an inner envelope or air passageway completely surrounding and defining the commodity space and through which a body or current of air or other gaseous heat exchange medium can be made to circulate continuously,

a mechanical refrigerator or other suitable heat exchanger being located in the path of said current of air. The comon wall or membrane separating said inner and outer envelopes being air-tight but vapor-permeable so that under the influence of a proper temperature gradientacross said common wall, vapor entrained within the outer envelope will seek its way through said. common wall into said inner envelope to there be entrained in the current of air circulating therethrough and subsequently condensed on the coils of the refrigerator. In this manner then itis possible to maintain the air within the insulating blanket in a dehydrated or dry condition thereby to in-- crease its efficiency as an insulator. Furthermore since the inner wall of the inner envelope is vapor-tight as well and thus the imposition of anundue load onthe refrig-.-

eratorcoils is obviated.

as air-tight, the migration of moisture from the come the air circulation envelope therethrough. To compensate in part for the lack of such circulation through the doors we have developed andresortto the use of the door and door frame construction illustrated in Figures 2 6 part of the present invention, it should be noted that any conventional mechanism can be used for this purpose.

It will be seen that as a result of the structure above disclosed, we have provided a refrigerating car having a and 3 wherein both the door and itsassociated frame are rimmed or bounded by a metal frame, one being inheat exchange relationship with the inner car side air'envelope and the other being in heat exchange relationship with'a closed dead airenvelop-e formed in the door. p

More particularly and as illustrated in Figuresl2 ands, each door frameis bounded by wooden studs 61 and upper and lower wooden cross members 62 and, 63 all suitably attached to the car frame. Fa'stened toeach of the studs 61 interiorly thereof is a metal U-shaped channel 64 serving to seal oflf the adjacent open end of car side air envelope or flue and forming a continuation thereof. Secured to the upper cross member 62 interiorly thereof and slightly spaced therefrom by a spacer 62a is a depending metal radiating plate 65 extending across the door opening and serving as a wall for the car ceiling air flue at this point. Formed on the lower edge of the plate 65 is a flange 66 secured to the cargo compartment ceiling 42 and serving to aid in supporting said ceiling at this point, Here it should be noticed that the air flue 43 including the plate 65 extends somewhat below the level of the upper end of the door frame and is in heat transfer relation therewith. Secured to the studs 61 and forming an integral part thereof are Z bars 67 serving as structural members and forming door corner indentations or recesses. Here it should be noticed that the car side sheathing 23 overlaps the outer faces of the Z bars 67 and is secured and sealed thereto.

Closing and sealing the door frame so formed is a door including an outer metal sheathing'68 interiorlycoated with a layer 69 of asphalt and secured to marginal horizontal structural angles 71 and vertical structural angles 72. Secured to and seated within the corners of the angles 71 and 72 are wooden strips 73 each faced on its inner side with a resilient gasket 74. Attached to the angles 71 and 72 interiorly thereof is a rectangular wooden frame 75 and secured to the inner face of the'door sheathing 68 are horizontally extending bracing and spacing metal channels 76. Secured to the upper and lower wooden cross members of the rectangular frame 75 is an air-tight vapor-permeable membrane or sheet 77 conveniently made of pressed wood, hardboard or porous Masonite. Disposed between the membrane 77 and the channels 76 is an insulating layer or blanket 78 of glass or slag wool and covering the outer face of this blanket is an airand vapor-tight sheet 79 of treated paper. Optionally the sheet 79 can be covered with a layer 81 of heat reflecting metal foil such as aluminum foil.

Secured over the inner face of each door is a sheet or panel 82 of plywood held in spaced relation to the sheet 77 by spacing members 83 so as to form an air channel 84. Here it should be noted that the upper and lower edges of the sheet or panel 82 stops somewhat short respectively of the cargo compartment ceiling 42 and floor 9 thus providing air gaps 82a and 82b for the circulation of air from the cargo compartment through the air channel 84. From Fig. 3 it will be noted that the inner vertical door edges are lined and reinforced with metal angles 85, arranged when the door is closed, practically to lie immediately adjacent the metal channels 64 of the door frame and there to be in good heat transfer relation to said channels 64. Formed in the spacing members 83 and the metal angles 85 are horizontally extending air holes 86.

Although no mechanism for opening and closing the car doors has been illustrated inasmuch as it forms no cargo space defined and enclosed by an air circulating envelope in closed circuit with the cooling coils of a mechanical refrigerator and having no communication with either the cargo compartment or the outer space. In

addition to this, the inner air circulating envelope is' itself surrounded by an outer insulated envelope sealed on its exterior 'side against'the ingress of both air and moisture but separated from'the inner air circulating envelope by a moisture-permeable wall so that any moisture present in the outer envelope can pass into the inner envelope to there be entrained in the current of air circulating therethrough and. then condensed on the coils of the refrigerating unit.

Although .the inner air circulating envelope is of necessity interrupted at the car openings, compensation therefor has been made by bringing the upper inner edge of each door into heat transfer relation with the metal plates 65 forming the sides of the ceiling flue 43 and by placing the inner vertical edges of the doors in heat transfer relation with the metal channels 64 defining the inner air circulating envelope at the door openings.

From Figure 1 it will be noted that the air within the inner envelope travels counterclockwise as viewed in this figure and that consequently, the air chilled by the refrigerating coils 55 first passes into and through the ceiling flue 43, then downwardly into the car side fiues and car end flue 22, and finally back to the cooling coils, Although no particular stress is laid on the depth or thickness of theseflues they should be so related with each other and with the velocity of the air current to bring about the above result. It is for this reason that the ceiling flue 43 is illustrated as being of a greater depth than the depth of the side wall, end and floor flues. Since within the cargo space, the warmer air is displaced to the upper regions thereof by the colder air, the warmer air is always in heat transfer relation with the aluminum ceiling plate 42 which in turn is in heat transfer relation with the chilled air passing thereover. The air from the ceiling flue 43 and which has absorbed some heat from the ceiling plate 42 then passes downwardly through the side wall and end flues and in so doing absorbs additional heat therefrom. As a result of this construction and action, it will be seen that a condition is approached wherein there is a substantially constant temperature gradient between the circulating air and the walls which it progressively contacts.

Since the cooling coils are in contact only with air circulating through the inner envelope and since this envelope is completely sealed, the only moisture to which the coils are subjected and which condenses thereon, is that which is entrained within the outer envelope and which, due to the temperature gradient between the outer and inner envelope, passes through the intervening wall into the inner envelope. These conditions exist regardless of whether the car doors are open or shut. We have found that by resorting to this expedient refrigerator cars can be taken across the United States from coast to coast without the necessity of defrosting the refrigerator coils whereas without this expedient the coils had to be defrosted every eight hours enroute.

By maintaining the outer envelope free of moisture, the insulating efiiciency thereof is of course maintained at a higher level for the simple reason that the heat conductivity of dry air is far greater than that of moist air.

In the claims appended hereto the phrase outer wall is used relative to the inner common wall of the inner and outer envelopes. For example, as so used the outer walls of the inner envelope refer to the walls immediately defining the cargo compartment whereas the outer walls of the outer envelope refer to the outermost walls 2,874,554 7 8 of the structure immediately surrounded by the atmos- 3, wherein said blower is positioned. so as to firstforce phere. air from said cooling means over the ceiling of said'inner.

We claim: casing and thenbelow the floor thereof and back to said 1. A refrigerating unit comprising: nested, but spaced, outer, intermediate, and inner casings, each defined by side walls, end walls, a floor, and a ceiling, said. outer and inner casings being air andmoisture-tight and said intermediate casing being air tight but moisture permeable- 2. A refrigerating unit of the character defined in claim 1, wherein the thermal conductivity of the ceiling of said inner casing is substantially greater than that of its floor.

3. A refrigerating unit. of the character defined in claim 1, wherein cooling means is disposed between one pair of adjacent end walls of said inner and intermediate casings and wherein a blower is locatedbetween. said inner and.

intermediate walls for circulating air through the space formed between said inner and intermediate.- casings.

4. A refrigerating unit of thecharacter defined in claim cooling means.

References Cited in the file of this patent UNITED STATES PATENTS 1,864,259 7 Small ..-June 21, 1932 2,497,713 Becker Feb. 14, 1950 2,540,331 Hlavaty Feb. 6, 1951 2,586,893 Westling Feb. 26, 1952 2,589,551 Iwashita Mar. 18, 1952 2,613,509 Philipp Oct. 14, 1952 2,633,003 Jordan Mar. 31, 1953 2,644,317" Haywood July 7, 1953 2,780,923

Jones Feb. 12,1957'

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