US2244005A - Refrigeration insulation - Google Patents

Description

n Jun? 3, 1941' A. l.l GUs\TlN, JR., ETAL 2,244,005

REFRIGERATION INSULATION i Filed Feb. 17. 1939 2 Sheets-Sheet 1 ENToRs v llllllllllllll a.

Jimi! 3, 1941 A. L.. GUsTlN, JR., Erm. 2,244,005

REFRIGERATION INSULATION Filed Feb. 17, 1959 2 Sheets-Sheet 2 QQ INVENT R5,

Patented Jurre 3, 1941 UNITED STATE REFRIGERATION INSULATION Albert L. Gustin, Jr., and Jay O. Brelsford, Kansas City, Mo., asslgnors to Gustin-Bacon Manufacturing Co., Kansas City, Mo., a corporation of Missouri Application February 11, '1939, serial 10.256.904

(c1. sz- 119) 11 Claims.

Our invention relates to refrigeration insulation, and more particularly to the structure` of the insulated walls of a refrigerated space.

It is common to insulate refrigerated spaces by enclosing them in double walls, comprising an inner wall positioned in spaced relation to an outer wall, with the inter-wall space filled with heat insulating material, such as ground cork, balsam wood, rock wool, glass wool, kapok and the like. It was soon observed that the insulating material became impregnated with moisture, greatly lessening its heat insulating qualities. Frequently the accumulations of moisture would rot those nsulations comprising derivatives of wood or organic material.

Attempts have been made to seal the insulating material in water-proof envelopes. It has been found, however, that this is ineffective since envelopes which are Water-proof are not vapor proof. That portion of the envelope which contacts the cold wall will be chilled below the dew point, causing a precipitation of moisture and lowering the vapor pressure. Vapor at higher vapor pressure will pass through `the waterproofing and condense against the cold wall, with the result that moisture will collect in the insulation. It is so dilcult to render a wall vapor proof as to be substantially commercially unfeasible.

Prior attempts to solve the problem'of providing an insulating wall construction for refrigerated spaces have proceeded on the theory that there was breathing, due to barometric and temperature changes. Provision was made to permit breathing `from the cold side. 'I'his proved to be generally ineffective. Our research has shown us that vapor will pass through the a condensing surface at a sunicient velocity to prevent their condensation within the inter-wall space.

One object of our invention is to' provide an insulated wall construction for refrigerated spaces.

Another object of our invention is to provide an insulated refrigerator car for railway use in which the insulation will be maintained in a substantially dry state over extensive periods of time.

A further object of our invention is to provide a novel insulated dri-p pan construction for refrigerator cars.

Other and further objects of our invention will appear from the following description.

In the accompanying drawings which form part of the instant specification, and which are to be read in conjunction therewith, and in which like reference numerals are used to indicate like partsinthe various views: Fig. 1 is a sectional view of the end of a re- `ses outer wall and insulating material to the cold wall or cold side in almost straight lines. The resistance to flow of vapors through the insulating material so reduces their velocity that before they can escape from the insulation, they are condensed adjacent the cold side by being chilled below their dew point. Once moisture is precipitated, it further reduces the velocity of flow of. the vapors through the insulating material, with the result that the condensation of vapors in the insulation continues progressively, becoming rapidly worse as the insulation becomes saturated with moisture.

We have determined that it is possible to insulatea refrigerated Vspace and maintain the insulation in substantially dry condition. We have solved the problem by permitting the vapors to flow through the insulation out of contact with frigerator car showing our novel drip pan construction which embodies the principles of our wall construction.

Fig. 2 is an enlarged` sectional fragmentary view of a wall construction showing one mode of carrying out our invention. l

Fig. 3 is a sectional view of a wall construction showing another embodiment of our invention.

Fig. 4 is an enlarged fragmentary sectional view of the drain of the drip pan construction shown in Fig. 1.

Fig. 5 is a sectional view with parts broken away, of a refrigerator car showing another embodiment of our invention.

In general; our invention contemplates the provision of a pair of walls spacedly positioned from each other to define an inter-wall space. One wall forms the boundary wall of the refrigerated chamber. The outerawall is in contact with warm air. Positioned between the walls we provide heat insulating material of any suitable type. The heat insulating material,. however, must be such that it will offer minimum resistance to the passage of the vapors. The insulation between the walls is not permitted to contact the cold wall, that is, the inner wall adjacent the refrigerated space. We have found that if the insulating material contacts, or is closely adiacent to the cold wall, vapors will condense upon the cold wall before they can escape from the inter-wall space. The space formed by the inner surface of the insulating material is vented to the space of lower vapor pressure. Inasmuch as there is no insulation material in the space communicating with the vents, the passage of vapors from this space through the vents into the space of lower vapor pressure is sufficiently rapid to prevent the condensation of vapors until they have escaped into the cold space of lower vapor pressure. We have found there is a definite relationship between the rate of vapor penetration and the venting area. If we permitted the free passage of vapors into the insulating material, a large venting area would be necessary in order to preclude condensation within the inter-wall space. In order to be able to use a smaller venting area, we seal the warmr side of the insulation with any suitable waterproof material. As indicated' above, we have been able to find no material which will prevent the passage of vapors. The sealing of the warm side by a water-proof material such as sheet rubber, asphalt or tar impregnated cloth or paper, pitch, and the like, however, will reduce the iiow of vapors into the insulation enabling us to insure the removal of these vapors from the insulating material rapidly with the use ofa reduced venting area. We have found, furthermore, that even in cases where the insulating material is initially moistened, that our construction will enable the moisture to be evaporated from the insulation so that it will ultimately become dry..

'Ihe provision of means communicating with a space of lower vapor pressure to the space adjacent the insulation, that is, between the surface of the insulating material and the cold wall, will insure the evaporation of such moisture as may be present in' the insulation. If the insulation is of such character that it does not present a too great resistance to vapor flow, the communication of the insulation with the zone of lower vapor pressure will effect the evaporation of any free moisture initially present.

We have found that an insulating material made of fibres of glass is excellent for use in our invention, inasmuch as this material appears to present a decreased resistance to the flow. 'Ihis enables the vapors to pass quickly into the insudensation within the cold space. If the passage of vapors is impeded condensation will take place upon the outside of the cold wall, with the result that moisture may drip or run onto the insulation. If this condition exists, the vapor velocity will be too small to effectively evaporate the moisture, and the insulation will become gradually saturated with moisture.

More particularly, referring now to the drawings, Fig. 1 discloses a fragmentary sectional view of one end of a refrigerator car, showing the usual ice bunker I. Ordinarily the temperatures within the refrigerator car are not sumciently low to present a severe problem, and the refrigerator car is shown with an outer Wall 2, and an inner wall 3, between which, secured in any suitable manner, is an insulating blanket 4. The innerl wall 3 is usually at a temperature sufciently high that vapors may escape from the insulating blanket 4 without condensing therein. In order to insure that this takes place, we have sealed the warm side of the insulation blanket, which is adjacent the ice bunker, with a layer of sealing material 5. As the ice melts, the water, at temperatures in the vicinity of 32 F., will drip into a drip pan 6. The surface of the drip pan will be sufficiently cold so that vapors will condense rapidly within the insulation outboard of the drip pan in the usual construction.

It will be noted that in the region of the drip pan we have provided insulating material 1, the

lation-free space adjacent the cold wall for conwarm side of which is sealed by sealing material 8. The insulation 1 is spaced from the cold drip pan 6 and does not contact it. This provides a free space 9 between the cold wall and the insulation 1. The space 9 is vented by a plurality of vents I0, each fitted with caps I I to prevent the passage of moisture into the insulated space. The insulation is such that the vapors will pass freely through the insulation 1, it being of a character which presents a reduced impedance to vapor flow, such as glass wool or the like. The resistance to vapor owin the space 9 is exceedingly small. This space is vented by the plurality of vents I 0. As the vapor leaves the insulating material 1, it is not in contact with anything sufliciently cold to condense it. When the vapor does contact a. cold surface it is flowing at a suiiicient velocity so that condensation will not take place until the vapor has escaped into the cold compartment where condensation will ultimately take place by contact with the refrigerating medium, which may be ice or expansion coils connected to suitable refrigerating apparatus.

The remainder of the car shown in Fig. 1 is provided with the customary insulating blanket I2, as the temperature of the cold wall I3 is not sufliciently low to condense vapors severely.

In the embodiment just described, it Will be observed that this specific embodiment of our invention has been applied only to that portion oI.' l

the refrigerator car which presents surface sumciently cold to cause rapid condensation of vapors within the insulation. This constructionv need not be employedfor the remainder of the car in this case because the velocity of vapor iiow through the inner wooden side walls 3 is sufficiently great for `the temperatures involved to insure that condensation will not take place if the Warm side is sealed. It will be understood that the construction shown in Fig. 1 for the side wall adjacent the ice bunker may be employed in many cases where the vapor pressure on the cold side is not too low. It will be further observed that the wooden wall is a permeable one which is in effect venting the insulation over its entire cold surface. If the wall is sumciently permeable and the warm side is sealed, the principles of our invention operate and the insulation will remain dry.

Fig. 2 shows a fragmentary sectional view of a wall designed to be employed for spaces refrigerated to a low temperature, such as cold storage spaces and the like. 'I'he outer wall is indicated at I4 and the inner Wall at I5. Insulation I6 is secured in any suitable manner to the outer or warm wall I4. The warm side of the insulation is sealed by a layer of material I1. The upper surface I8 of the insulation I6 is spaced from the cold wall I5, providing a space I9. The cold wall I5 is provided with a plurality of vents 20 fitted with cap members 2|. The arrows in Fig. 2 show the direction of vapor ow from the space of high'vapor pressure to the space of lower vapor pressure. The insulation I6 is of the type which will present a predetermined minimum resistance to the flow of vapors. The venting area may be determined empirically and is a function of the effectiveness of the sealing layer I1 as a vapor barrier, the difference in vapor pressure between the refrigerated space and the space without and the resistance to flow of vapors through the insulating material I6. The wall structure may be so designed that the venting area will be suflicient to permit a rapid ow of sometimes operated in heating service.

Vcooling means in the ice bunkers.

vapors from the space I9 out' through the vent and into the space of lower vapor pressure.

Due to the fact that there is an unobstructed space between the cold wall and the upper surface I8 of the insulation I6, the. fiow of vapors escaping from the insulation will be directly to the vents and out into the cold space.

Referring now to Fig. 3, we have shown another embodiment of our invention, in which the insulation IB is placed against the warm wall I4 and spaced from the cold wall I5. We provide'an auxiliary wall 22 spaced from the cold wall I5. The wall 22 will be at a temperature suillciently high so that vapors contacting it will not condense. A plurality of vents 23 are provided through the wall 22 into the space 24 between the wall 22 and the cold wall I5. The vents 23 are provided with cover members 25. The space 24 is provided with vent pipes 26 leading to the refrigerated space of lower vapor pressure, to which the vapors pass for condensation. Due to the fact that the space 24 is unobstructed, vapors will readily ow to the vents. The insulation I6 is sealed at its warm side by a sealing layerk I1. The sealing layervreduces the passage of vapors into the insulation but, as pointed out hereinabove, will not prevent vapor passage. After the vapors pass the barrier I1, they will flow through the insulation I6 which is of such character as to present a reduced -resistance to vapor ow. The wall surface 22 is not sufficiently cold to cause condensation so that the vapors will escape in the vapor phase into the unobstructed space 24 formed by the wall 22 and the wall I5, 'and flow out through the vents 26. When the construe tion is used in refrigerator cars we may provide valves 21 in the vent pipes 2B.

In the winter season refrigerator cars are During such use heating means are provided instead of When refrigerator cars are operated in heating service, the valves 21 are closed.l The difference in vapor pressure between the inside of the car and that Ain the space 24 is usually sufficiently low when refrigerator cars are operated in heating service that there is no problem of passage of vapors through the wall I5.

Referring now to Fig. 4, the bottom of the drip pan 6 may be covered with a water-proof layer 2B, which may be pitch, rubber, or the like. Water from melting ice passes into sumps 29. The sumps and drain pipes 30 may be made out of non-metallic material, such as phenol condensation products, hard rubber or the like. A cap member 3I is fitted over the drain pipe forming a trap and providing a water seal between the outside air and the interior of the ice bunker. A water-proof sleeve 32, which may be made out of rubber or any other suitable material, seals the insulation 1 from contact with the drain pipes 30. Any condensation on the outside of the drain pipes will therefore not affect the insulation.

Referring now to Fig. 5, we have shown a refrigerator oar fitted with one embodiment of our invention. Refrigerator cars pass through many lt will be noted that we provided insulation 33 completely around the space to be refrigerated. The insulation is placed adjacent the warm wall, that is, the outside wall of the car.\` A sealing layer 34 seals the warm side of the insulation. The insulation itself is spaced from the inside walls 35 and the bottom wall or floor 36,'and from the ceiling 31, providing a space 38 formed by the cold wall and the inside surface of the insulation 33. The insulation is of the character which will prese'nt a minimum resistance to vapor flow. The unobstructed space 38 is vented into the cold space through a plurality of vents 39. Under the ice bunker I we provide the drip pan 6, covered with water-proofing material 28. It will be noted that the floor of the car, 36,

is likewise covered with a water-proof layer III.A

Due to the fact thatA the drip pan 6 is colder than any other interior wall of the refrigerator car, we provide the vents II), provided with cap members I I, in the region of the drip pan, to provide for the rapid venting of vapors from the space 38 immediately below the drip pan 6.

It will be apparent from the foregoing that the construction shown in Fig. 5 will insulate the refrigerator car and preclude the condensation of vapors in the insu1ation,.thus maintaining it dry and of unimpaired eiciency.

Referring again to Fig. l, it will be noted that the transverse structural member supports a vertical portion of the sealing means 8, which seals the warm side of the insulation 1. The sealing means in the transverse structural member 50 provides a water-proof barrier separating the insulation 1 underneath the drip pan 6 and the main insulation blanket I2 of-the main car body.

It will be understood, of course, that in the instant invention the object of the sealing means 8 is to prevent the migrationof vapors into the insulation 1. The barrier just described has another important purpose. Occasionally the drain opening may become clogged, permitting the accumulation of water from the melted ice in the of the drip pan may occur, into the insulation.

climatic conditionsland are subjected frequently to severe tests for the insulation. With some drip pan. Motion of the car may cause this water to overow through the vents onto the insulation, thus wetting it. Sometimes corrosion permitting leakage In event of accidental overflow of moisture due to clogging of the drip pan drain, our construction is such that the moisture will ultimately be dried due to the venting to the space oflower vapor pressure. If our vents become clogged, condensation will then take place against the cold surface since the space above the insulation is not in communication with the space of lower Vapor pressure. In such case condensation upon the outer cold side of the drip pan will cause moisture to drip onto the insulation.

The remaining portion of the car, however, has the customary insulation I2, and should this become wet it will remain wet, thus impairing its eiiiciency. The water-proof barrier 50 will pre'- vent migration of such moisture, as will accidentally accumulate in the insulation 1, along the insulation situated under the remaining body of the car. This insulation is customarily in the form of blankets which are stitched for ease in handling. or channels along which the moisture may flow. Then, too, moisture may pass to the remaining insulation by capillary action, were it not for the barrier which we provide.

It will be seen that we have accomplished the The stitching forms actual troughs insulating wall construction for refrigerated spaces in which we are able to preclude the condensation of vapors in the insulating material. We have provided a drip pan construction which may be used on existing refrigerator cars to prevent the break down of the insulation at the trouble spot.

It will be understood that certain features and sub-combinations are of utility and may be employed without reference to other features and sub-combinations. This is contemplated by and is within the scope of our claims. It is further obvious that various changes may be made in details within the scope of. our claims without departing from the spirit of our invention. It is, therefore, to be understood that our invention is not to be limited to the specific-details shown and described. 1

Having thus described our invention, we claim:

1.,A.n insulated'wall construction for refrigerated spaces including in combination, an inner wall forming a boundary for' the refrigerated space, an vouter wall spaced from said inner wall, fibrous heat insulating material positionedin the inter-wail space adjacent-the outer wall havingv a surface spaced from the inner wall and .forming a passageway therewith, sealing meansvfcr said insulation adjacent the outer wall, and means providing communication between said passageway and the space being refrigerated.

2. A wall construction for refrigerated spaces including in combination a cold Wall forming a boundary for the refrigerated space, a warm wall spacedly positioned from said cold wall, fibrous heat" insulating material located in said interwall space adjacent the warm wall having a surface spaced from said cold wall and forming a passageway therewith, said insulating material being of suchv character as to permit the ready passage of vapors therethrough, means for sealing said insulation adjacent the warm Wall, and means providing communication between, said passageway and the space being refrigerated.

3. A drip pan construction for'refrigeratoir cars including in combination a drip pan adapted to be positioned under the ice bunker of the refrigerator car, insulation positioned below said drip pan and spaced therefrom to form a passageway therewith, and means for venting said passageway into said ice bunker.

objects of our invention.- We have provided an a drain pipe for said drip pan passing through said insulation, means for sealing said drain pipe from said insulation, a water seal for said drain pipe, and means providing communication between said passageway and the interior of the refrigerator car.

6. A wall construction for a. refrigerated space including in combination a cold wall forming a boundary for the refrigerated space, an outer wall spacedly positioned from said cold wall, a third wall intermediate said cold wall and said outer wall, fibrous heat insulating material positioned between said third wall and said outer wall, sealing means for said insulation adjacent lsaid outer wall, said third wall being spacedly positioned from said cold wall and forming a` passageway therewith, means providing communication between said insulation and said passageway, and meansV providing communication be- -tween said passageway and the space being refri'gerated.

7. A wall construction as in claimV 6 in which Asaid heat insulating material permits the ready passage of vapors therethrough.

8. In an insulated wall construction for refrigerated spaces,v an inner cold wall, said wall being ymade vof permeable material, an outer warm wall spacedly 'positioned from the cold wall, fibrous heat insulating material in the inter-wall space, and means for sealing said insulation adjacent the outer warm'wall.

9. A wail construction for a refrigerated space including in combination a cold wall forming a boundary for the refrigerated space, an *outer wall spacedly positioned from said cold wall, a

third wall intermediate said cold wail and said outer wall, fibrous heat insulating material posi'- tioned between the third wall and said outer wall,

face of the insulation remote from said drip pan,

means for sealing -said insulation adjacent said outer wall, and means for providing communil cation between said insulation and the passagef Way formed by said cold wall and said third wall.' 10. In a refrigerator car having an ice bunker and a main body, a drip pan undersaidice bunlrfY er, insulation under said drip'p'an V'andinsulation under said main body, and -a waterproof lbarrier between said insulations. f5

11. A wail construction for a refrigerated space including in combination a cold wall forming a boundary for'the refrigerated space, 4an outer Wall spacedly positioned from said cold wall, a third wall intermediate said cold Wall and said outer wall, heat insulating material positioned ,between said third wall and said outer wall, said third wall being spacedly positioned from said cold wall and forming a passageway therewith, means providing communication between said insulation and said passageway, means providing communication between said passageway and the space being refrigerated,-and a valve for said means providing communication between said passageway and the refrigerated space.

- ALBERT L. GUSTIN, Ja.

JAY O. BRELSFORD.

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