US2281815A - Air conditioning - Google Patents

Description

Patented May 5, 1942 AIB CONDI'IONIN G Edmund Alunni-ch, Neenhajg'n, near Berlin,

Germany i Application september so, 1937, serai No. 166,466 a In Germany October 2, 1936 15 Claims.

This invention relates to apparatus for maintaining refrigerated air at substantially uniform humidity. It is well known that the relative humidity of the air in refrigerator cabinets varies over a wide range. This' variation is due primarily to the fact that the refrigerator operates intermittently in response to the load on-the machine and the temperature condition in the space being cooled. In this type of refrigerator, when the evaporator is operating, the relative humidity is too low due to the low temperature of the evaporator, and when the evaporator is not functioning the relative humidity rises. This varia- (cl. sz-ss) tion in moisture content in the air is undesirable.

Attempts have been made to reduce these variations in relative humidity by starting and stopping the refrigerator frequently, and also by providing cold storage devices. The first of these remedies is not applicable if the electric current is interrupted forseveral hours, and the latter remedy is not practical because it is undesirable and impractical to provide refrigerators with cold accumulators. Attempts have also been made to increase the relative humidity by evaporating water into the air.

One of the objects of this invention is to provide means whereby the relative humidity of cooled chambers may be maintained substantially constant in a manner which is independent of the frequency of operation of the cooling means for the chamber or the length of the periods of operation of the cooling means. More specifically, it is an object of my inventionto utilize hygroscopic material in such relationship to the cooling means for -a chamber as to absorb moisture from the air whenever the relative humidity tends to rise and to liberate moisture whenever the relative humidity of the air tends should -be so arranged that at least part of it is in the stream of the air close to the evaporator, .but protected from water dripping therefrom.

According to my invention, when the refrigerator is operating, the air first passes over the evaporator and a portion of this air comes into direct contact with the cold surface thereof. vA considerable amount of water is likely to condense as this air contacts the cold surface of the evaporator thus leaving this air quite dry. This relatively dry air mixes with the air which does not directly contact the cold evaporator surface and then circulates 'about and contacts moist hygroscopic material and absorbs water from the 4Vlatter prior to circulating into the room being cooled. This comes about by reason of the fact that the mixture of air flowing from theevaporator to the hygroscopic material has a higher i temperature than'that which directly contacted the cold surface of the evaporator and its relative humidity is therefore lowered due to the moisture condensed out of that portion whichl terial is in condition to -pick up moisture from the air circulating thereabout. In other words, when the refrigerator is operating, the hygroscopic material gives up moisture to the air which results in a further cooling of the air stream;

and when the refrigerator is not operating therelatively dry hygroscopic material absorbs moisaccordingly of advantage to provide means for terial should be large in proportion to its weight,

and the material should be so arranged that it offers only small resistance to the circulation of the box air thereov'er. Preferably the material ture from the air as soon as the relative humidity rises, and this absorption results in a slight heating of the air.

This invention is primarily applicable "to refrigerators in which the period when the refrigerator is operating is short relative to the period in which the refrigerator is not operating or to those in which both periods are comparatively long such as is used for large storage chambers for meats and other bulky products which must be maintained in a comparatively moist condition. 1 In such machines, when the refrigerator is. not in operation the surface of the evaporator will become appreciably warmer than during the period when the refrigerator is operating. The frost formed on the evaporator during operating periods will thus slowly evaporate into the air stream and this evaporated moisture will be absorbed in the hygroscopic material as described and replenish the moisture supply for addition to the air stream during the period the refrigerator is operating, and thus maintain the humidity of the circulating air at a more even value.

If desired, the `hygroscopic material may be placed in heat transfer relation with a coldstoring device, which stores the cooling effect caused by the extraction of water from the hygroscopic material, and when the latter absorbs water the heat of absorption liberated is absorbed by the cold-storing device. The type of coldstoring device proposed by me is easily installed in a refrigerator and renewal is not necessary.

Since it is desirable to replace the hygroscopic material, and also to maintain portions thereof ln heat transfer relation to the cold-storer or accumulator, I have provided a simple and easily operated means for detachably securing bodies oi hygroscopic material to they accumulator.

Other objects and advantages will become apparent in the vfollowing description and drawing in which like numerals are employed to designate like parts throughout the several views.

Fig. l is a broken elevation of the refrigerator respectively.. This arrangement of. the supportcontrol element embracing a cold-storing device, r

and

Fig. 8 is a section on the lines t--d of Fig. 7.

Figures 1 and 2 show a preferred arrangement of cold-storing elements it and humidity control elements ii with respect to an evaporator i2 of a refrigerator generally indicated by numeral 53. lt will be observed that these elements are disposed at one end oi a room it. not completely shownfand which is to be cooled and uniformly humidified. In order to forni a definite path 'lor circulating the air in the direction indicated by the arrows in Fig. 2, panels 2t, 2i and 22 may be positioned near rear wall 23 to provide therebe tween a conduit or passage 2. The top panel terminates short of the top Wall 25, to provide an inlet opening Et above the evaporator i2 to pas= sage 2d. Spaced from the rear panel t? is a lower front panel 2l forming a passage 28 therebetween having an outlet 29 formed between the front panels Ztl and 2l. These panels may be secured to the side walls of the refrigerator by any suitable means as by screws 3d. As shown, the evaporator comprises coiled pipe i9 having an inlet 3i and an outlet 32 and is provided with heat absorbing hns 33.

The accumulator elements it are shown in detail in Figs. 7 and 8 and comprise an elongated cylindrical metal casing closed at both ends and filled partly with a cold-storing liquid lit having a fairly large heat of fusion at the tem perature desired in the room to be cooled. At temperatures below the melting point of ice, aqueous solutions of inorganic substances, for example common salt, may be used. Surrounding substantially the longitudinal length of the casing 35 is a hygroscopic material 31, composed for example, of a corrugated paper container t@ having its cavities adjacent casing 35 lled with fullers earth, or the like. The hygr'oscopic. element 31 does. not completely envelop the casing 35, but has its longitudinal edges separated as indicated at 39 in Fig. 8,4 so that it may easily be removed from the casing 35 whenever desired. The cold-storing effect of the liquid 36 can be adjusted to any desiredrelation with respect to the absorption eiect of the hygroscopic material A31 by altering the size of the casing 35 with respect to the quantity of the hygroscopic material 31.

The cold-storing elements It are supported in the air passage 24 by means of spaced brackets 40 mounted on the horizontal panel 2| and having upwardly extending biiurcated arms 4l to which are attached arcuate spring clamps 42 for detachably receiving the cold-storing elements I0. A drip pan 45 is supported by the upper ends of the bifurcated arms M, and functions to collect the liquids that drip from the evaporator l2 to prevent the liquid from contacting the hygroscopic materials.

As shown in Figs. l and 2, the humidity control elements il are suspended from hooks carried by a pluralityof spaced panels 5l supported by the front and rear panels 21 and 22 ing panels 3i provides a plurality of separate air conduits di for circulating the air about the elements' i i.

One oi the humidity control .elementsv ii is shown in detail in Figs. 3 and 4 and comprises an elongated, substantially elliptical body t3 having a covering ed of material pervious to water vapor, such as paper, and contains a hygroscopic mate rial 55, for 'example sawdust. The ends of the covering 5d are glued together to form tabs 5t y one oi' which is provided with an aperture tl for suspending the element lt from one oi the hooks 5t.

Another form' of humidity control element t@ is shown in Figs. 5 and 6 and comprises an elongated cylindrical body having a wire screen cover @2 containing a hygroscopic material such as silica gel t3; One end td of the covering is closed and the other end is provided with a threaded coupling d5 for the removable connection of a cap t@ wherebyD the wire screen or silica gel can be replaced. An owning t?! is provided in the cap for suspending the humidity control element from one of the hooks 5t.

linoperation, assuming that the evaporator i2 is operating, theair passes from room ld through the inlet it and contacts the cold surface of the evaporator U2. Theevaporator not only cools the air, but removes a considerable amount oi moisture from the air which comes into contact with its cold surfaces leaving this air quite dry. The air which contacted the cold surfaces of the evaporator mixes with other air owing adjacent to the evaporator, then passes downwardly into lthe conduit 2d and contacts the combined cold storage and hygroscopic elements id. |This air mixture has a lower relative humidity due to the ract that it is at a higher temperature than the part thereof which contacted the cold surfaces of the evaporator and some, of the moisture in that part was condensed out. Under these. conditions elements it have a temperature higher than the cooled air, and therefore the hygroscopic material 3l gives up waterr vapor to the air increasing its relative humidity. The heat required to evaporate the moisture is derived from the cold-storing elements, and consequently these elements are cooled as the air is humidified. Some heat may also be taken from the air. The hygroscopic material 31 being in contact with the cold-storing cylinder 35 will become quite dry because its temperature remains higher than the temperature of the cooled air due to the heating eect of'thel cold-storing cylinder 35. The air then continues to flow downwardly inconduit 24 and absorbs a small amount of heat by contacting the adjacent wallsof the box, and then passes and are thus prepared to absorb water vapor from the air when the evaporator is not operating.

When the operation of the evaporator is discontinued, the air contiuues to circulate in the same direction as previously because the evaporator and the cold storing elements are located at the top of the -confined air passage. Since the temperature of the evaporator soon begins to rise, the air will no longer be dried by condensation. If the humidity tends torise due partly to the dehydration of food or other materials being stored in the refrigerator and partly due to the gradual evaporation of frost or condensate from the evaporator due to its rise in temperature, the dry hygroscopic material in the air passage will absorb this moisture. A'I'he heat of absorption produced at elements 31 is taken up by the cold-storing elements l0, while that produced 'at elements H is given up to the air. Since the elements Il are in the path of upwardly flowing air the heat generated therein by the absorption of moisture will augment the air circulation. It will be appreciated that the cold storing elements not only aid in circulating the air, but these are also very effective in reducing any excess humidity because their temperature remains lower than the box temperature. 1

If desired, the cold-storing devices l and humidity control elements Il may be arranged in a different manner. For example, they may be disposed in any part of the room M or in air ducts leading to other rooms to be cooled. 'I'he hygroo scopic elements I I may' be laminated or may con- `suitable to storefood, means providing an air list of corrugated paper discs which may be lled with fullers earth. The hygroscopic material may also be used in a rack employed for supporting the material to be refrigerated. Solid hygroscopic material of the organic type, may also be usedand is well adapted for easy replacement.

o From the foregoing description of my invention, it will be seen that I have provided a simple, inexpensive means for controlling the humidity of refrigerated spaces which is automatic in operation and yet requires no controls or regulating means. While I have describeda preferred way of practicing the invention it will be understood that the principle thereof may be carried out in various ways and by apparatus very different from that herein described.

I claim:

l. That method of conditioning air which comprises passing air from a space being conditioned passageway having separate oommunication'with both the top and bottom portions of said chammaterial in said passageway below said evaporator, said air circulating through said chamber andfpassageway by thermosyphdnic action, coming rst in contact with said evaporator and then with said hygromopic material, whereby the air is chilled and then humidiiied by the evaporation of moisture from said hygroscopic material. l. y

3. The 4combination set forth in the preceding claim characterized by the fact that at least some of said hygroscopic material is in heat exchange relation with bodies of high heat capacity whereby th'e heat of evaporation is supplied by said bodies thereby resulting in the chilling of said bodies so `as to maintain the temperature of the refrigerator chamber during inactive periodsof said apparatus.

4. A combined heat accumulator and humidity control device for refrigerated chambers comprising a self-contained heat storage element complete within itself, and means, including hygroscopic material mounted in heat exchange relation with said element, for absorbing moisture from ambient air when the humidity rises above a'desired value, and.for liberating moisture to the air when the humidity falls below a desired value, said heat storage element being operable to absorb heat of absorption during the absorption period, and to supply heat of evaporation during Athe period when the air is being humidified. l

1 5. A combined heat accumulator and humidity controldevice for refrigerated chambers comprising a'heat storage element complete within itself adapted to be supported in a refrigerated air passageway, and casing means readily pervious to moisture and containing hygroscopic material and adapted to be removably supported with said material in heat exchange relation withY said element, said device being operable to remove moistui'e from ambientair when lthe humidity is too high and to add moisture when the humidity is too low without appreciably affecting the temperature of the air as the result of absorption and evaporation of moisture.

6. The combination set forth in the preceding claim characterized by the fact that said casing is so constructed as `to have a larger surface area than is required to retain the volume of hygroscopic material contained therein. A

7. The combination set forth in claim 5 char acterized by the fact that said heat storage element contains a liquid having a low fusion tern-l perature.

8. The combination set forth in claim 5 characterized by the fact that said casing is sufficiently resilient to permit the same to be placed upon the heat storage element and to be frictionally operating, to control the humidity of the air,

said -humidity control also being operable to, absorb heat of absorption and to supply heat of evaporation whereby the temperature of the air is not materially affected by the operation of said humidity control.

11. In the art of conditioning a refrigerated space, in which air is circulated from the refrigerated space through a conditioning space and back to the refrigerated space, and in which a portion of theyairbefng circulated through the conditioning space comes into contact with a cold surface whereby the air is cooled and de hydrated by condensation of moisture therein onto the cold surface, that improvement which consists in bringing the previously cooled and dehydrated air into heat exchangewith compara- 'tively warm air from the refrigerated space and Vwith a body of high heat capacity conditioned to temper the previously cooled air and into contact with a body of hygroscopic material conditioned to give up moisture to the previously dehydrated air whereby the previously dehydrated air is humidied and the heat of evaporation of the moisture is supplied from the warm air in the refrigerated space and from the body of high heat capacity.

i2. in a refrigerating apparatus including a refrigerated space, an evaporator, and means for providing for the continuous circulation of air through said refrigerated space and over said evaporator,s`aid apparatus operating intermittently to evaporate refrigerant in said. evaporator whereby the circulating air is intermittently cooled and dehumidied by contact with the cold evaporator during the period when refrigerant is being evaporated in the evaporator and the previously condensed moisture is ,re-evaporated into the circulating air during the period when no evaporation is taking place in the evaporator, that improvement which'consists in placing a body of hygroscopic material in a position to contact the circulating air after having contacted said evaporator, whereby the hygroscopic material will absorb the moisture, evaporated into the air during the period when no evaporation is taking place in the evaporator and will give up the absorbed moisture to the dehydrated air during the period when evaporationy is taking place in the evaporator.

13. A refrigerating apparatus comprising, a refrigerated space, an evaporator positioned therein, means providing for the continuous circulation of air through said space and over said evaporator, said evaporator being operated intermittently to evaporate refrigerant therein, wherehy air contacting the surface of the evaporatcr is cooled'and dehumidifled by condensa-v tion' of moisture therein onto the cold surface of the evaporator during the period that refrigerant is evaporating in the evaporator and the condensed moisture is ire-evaporated into the circulating air during the period when no refrigerant is evaporating in the evaporator, and a hygroscopicbody positioned to be contacted by dit - i aasrsit the circulating air after it has come into contact withffthe evaporator whereby the hygroscopic body will absorb'the moisture evaporated into the circulating air during the period when no refrigerant is evaporating in the evaporator and will give up moisture to the dehumdied air during the periodv when refrigerant is evaporating in the evaporator so that the air in the refrigerated space will be maintained substantially constant, said hygroscopic body including a casing pervious to moisture containing hygroscopic material.

14. In the art of controlling the temperature and humidity of a refrigerated space, in which air is continuously circulated from the refrigerated space through a conditioning space and back to the refrigerated space,'in which a portion of the air being circulated through the conditioningspace comes into contact with a cold surface during one period whereby the air is cooled and dehydrated by condensation of moisture therein onto the coldsurface and the total moisture content of the. circulating air is reduced, and in which the moisture condensed on the cold surface is ive-evaporated into the circulating air during a second period, that improvement which consists in contacting the air circulating through the conditioning space during the first period with a hygroscopic material conditioned to give up moisture to the previously dehydrated air and in heat exchange with a body of high heat capacity conditioned to give up heat to the previously cooled air whereby the circulating air is humidifled and tempered during the first period and in contacting the air circulating through thel conditioning space during the second period with the previously dried hygroscopic material to absorb moisture evaporated into the air from the cold surface and into heatexchange with the previously cooled body of Ahigh heat capacity whereby the circulating air is dehumidiled and the heat oi absorption of the moisture is taken up by the body of high heat capacity during the second period.

l5. In the art of controlling the humidity of a refrigerated space, in which air is continuously circulated from the refrigerated space through a conditioning space and back to the refrigerated space, in which a portion of the air being circulated through the conditioning space cornes into contact with a cold surface during one period whereby the air is cooled and dehydrated by the condensation o f moisture therein onto the cold surface and the total moisture content of the circulating air is reduced, and in which the moisture fcondensed on the cold surface during the first period is re-evaporated into the circulating air during a second period, that improvement which consists in contacting the air circulating through the conditioning space duringA the first period with a hygroscopic material con ditioned to give up moisture to the previously dehydrated air and in contacting the air circulating through the conditioning space during the second period with the' previously dried hygroscopic material to absorb moisture evaporated into the air from the cold surface whereby moisture is absorbed by the hygroscopic material when the humidity of the air tends to rise and is liberated therefrom when the humidity tends to fall. 0

' EDMUND ALTENKIRCH.

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