US2645912A - Low side drier - Google Patents

Description

Jul 21, 1953 E. F. HUBACKER LOW SIDE DRIER Filed Nov. 9, 1949 fnz /enfor arl F I Patented July 21, 1953' tow SIDE DRIER Earl F. Hubackei', Muskegon, Mich, assignor to Borg-Warner Corporation, Chicago, Ill., acorporation of Illinois 1 Application November 9, 1949, Serial No. 126,293

This invention relates in general to a refrigerating system and to drying means therefor, and ithas particular reference to the provision of a drying unit, and its organization in the refrigerating system, in such manner that moisture is so eliminated from thesystem as to render it substantially anhydrous.

" 3 Claims. (Cl. 62-11735).

It has long been recognized that one of the essential elements of refrigerating apparatus presently being manufactured is a drier or like element for dehydrating the refrigerant as the latter passes from the compressor to the other parts of the closed cyclic refrigeraing system. Heretofore, these drier or dehydrating elements have usually been located adjacent the refrigerant condenser and within the machinery compartment of the refrigerator cabinet where they would be subjected to the heat generated and radiated by the motor compressor unit and the condenser in that compartment with the result that the temperature of the drier or dehydrator element often becomes so high as to render that element inoperative. This is particularly true for the reason that moisture retaining capacity of driers and like elements containing a dehydrant such as, for example, silica-gel, is somewhat inversely proportioned to their temperature. Moreover, it is also true that the temperature to which the refrigerant may be cooled in the condenser is dependent upon the temperature of the circulating air with the result that systems contain varying quantities of water, and

that such water often interferes with satisfactory operation, either corrosively, as .by'forming an acid with sulphur dioxide, or physically, as by freezing adjacent the capillary tube thereby to prevent the flow of refrigerant throughout the system. Many proposals'have been made to overcome the adverse effects of water, such as, for example, to incorporate a drying element in the circuit adjacent the compressor or condenser, the theory being that as the r fr g rant flows throu h 2 the drier, some of the excess water will be moved.

It is recognized that in the prior art numerous attempts have beenmade to provide a refrigerant drier of this general class and eiforts have been made to overcome thevarious deficiencies found in such prior art structures but to the best of the applicants knowledge the prior art structures have had only limited success and have been accorded only limited commercial recognition. It is believed that this fact results from. apparent deficiencies of the prior art structures, their nonadaptability for universal application and their expensive construction which so greatly increased the cost as to seriously handicap sales acceptance.

The present improvements in refrigerant driers are directed to simplify their construction and their mode of operation, and also to provide a refrigerant drier which may'readily and con-' veniently be employed universally to various types of refrigerating systems presently being commercially exploited. Moreover, the present denecessary and possible, thereby to effect a substantia1 reduction in the cost over the prevailing types of driers presently being employed.

According to one aspect of the present inven tion, the desired result may be obtained by utilizing a hydrophilic adsorbing agent as the drying medium, and disposing the drier proper in such a manner as to form a part of the evaporating element, or low side," of the refrigerating circuit. By employing a drier as taught by the present invention it is now possible to reduce the water content in the refrigerant to an extremely low value,that isto say, not more than five parts per million. When such dehydration is effected;

the system becomesanhydrous-for all practical purposes, and accordingly failures due to water in the circuit may be made nonexistent.

It has been found that thepreviously mentioned difficulties and objections encountered in connection with the preparation of driers and dehydrating elements in the circulating. system of refrigerating apparatus may be eliminated by submerging the drier, as taught by this invention, in the refrigerant disposed in the header of the evaporator as contrasted with the usual procedure where the drier is made a part of' the refrigerant circulating system which requires that the refrigerant flow through the drier housing in order to complete its cyclic path throughout the system. a By an arrangement such as this it. is obvious that the-capacity of the drierffor retainin moisture may be materially increased. Moreover, because of the fact that the drier is submerged in the refrigerant as contrasted with connecting the drier container with the refrigerant conduits, it is obvious that any moisture previously adsorbed 'by the drier will not be forced out of the drier due to the continuous passing of the refrigerant through the drier housing.

Accordingly, an object and accomplishment of the invention is to provide a refrigerant drier submerged in the refrigerant disposed in the low side of a refrigerating system and more particularly, submerging the drier in the refrigerant passing through the header of the evaporator.

Another object and accomplishment of the invention is to provide a refrigerating apparatus wherein substantially improved operating conditions are provided for the refrigerant drier or dehydrating element in the refrigerant circulating system. 7

A further object of the invention is to provide a refrigerating apparatus whereby there is afforded more efficient and reliable operation of a domestic refrigerator employing a capillary tube as the refrigerant flow control device.

Another object and accomplishment of the invention is to provide an improved refrigerant drier by corelating and especially designing the various elements thereof, whereby there shall be such cooperation between said improved elements as will best serve the purpose of providing an efficient refrigerant drier capable of being manufactured at low cost and yet giving maximum of satisfactory service in use.

The invention seeks, as a further object and accomplishment, to provide a refrigerating system and a refrigerant drier arrangement as contemplated herein and. characterized by an arrangement of parts .to more advantageously and satisfactorily perform the functions required of it and adapted to provide a compact unit which will successfully combine the factors of structural simplicity and durability, and yet be economical to manufacture.

Additional objects, features and advantages of the invention disclosed herein will be apparent to persons skilled in the art after the construction and operation are understood from the within description.

It is preferred to accomplish the various objects of the invention and to practice the same in substantially the manner as hereinafter more fully described, and, as more particularly pointed out in the appended claims.

With the above and other incidental objects in view, the invention has other marked improvements and superiorities which radically distinguishes it from presently known structures, these improvements in the invention residing in the novel construction and cooperative function of the parts thereof, the combination of the parts and the arrangement thereof as illustrated in the drawing and which will be more fully described hereinafter and particularly pointed out in the claims.

In the accompanying drawing on which there is shown a preferred embodiment of the invention,

Fig. 1 diagrammatically illustrates a refrigerating system incorporating the refrigerant drier and refrigerant drier arrangement contemplated by the present invention;

Fig. 2 is an elevational view of a portion of an evaporator of a refrigerating system with portions thereof cut away to clearly illustrate the refrigerant drier and refrigerant drier arrangement embodying the features of. this invention;

Fig. 3 is a sectional elevational view of the refrigerant drier embodying the features of the present invention and being taken substantially on the plane of the line 33 in Fig. 2;

Fig. 4 is a sectional view of the header of the evaporator depicted in Fig. 2 and illustrates a side view of the drier as being disposed in the header, said view being taken substantially on the plane of the line 4-4 in Fig. 2; and

Fig. 5 is an illustration of the drier proper with portions thereof shown in elevation and in section to more clearly illustrate the construction thereof.

The drawings are to be understood to be more or less of a schematic character for the purpose of illustrating and disclosing a typical or preferred form of the improvements contemplated herein and in the drawings like reference characters identify the same parts in the several views.

.As one possible example of advantageous employment of the refrigerant drier and refrigerant drier arrangement, reference is made to the drawings, particularly Fig. 1, wherein there is illustrated the refrigerant drier with which the present invention is particularly concerned and designated in its entirety by the numeral 20 as being operatively associated, for example, with a conventional refrigerating system designated in its entirety by the letter A.

The illustrated refrigerating system may comprise a motor compressor unit 2!, herein shown as being of the hermetically sealed type, and including an impervious casing within which is mounted an electric motor 22 and a directly connected compressor 23. After undergoing compression, the hot refrigerant flows through a discharge line 24, and through the convolutions of a condenser 25 which may be air-cooled by the usual conventional manner. This extraction of heat reduces in some degree both the pressure and temperature of the refrigerant, although both are quite high compared to normal atmospheric conditions.

After the mixed vapors and liquid refrigerant is discharged from the condenser it will flow through a conduit 26 into a valving device, which is illustrated in this connection as a capillary tube or restrictor 21, which is connected to an evaporator 28 having a header 29 in which the refrigerant drier 20 is operatively disposed. It is notable that the refrigerant is throttled in passing the restrictor 21, and thereafter will be expanded at the discharge side of the restrictcr and will be further expanded in the evaporator, so that it will become quite cold and is therefore capable of absorbing heat from the storage compartment of the refrigerator and from the contents thereof. After making its circuitous path through the evaporator, the evaporated and expended refrigerant is then returned to the compressor 2| by means of a suction line 30, thus completing the closed circuit.

Sufhce it to say, since the invention is not particularly concerned with the precise construction of the entire refrigerating system as illustrated, and/or its associated parts, they will not be further described in detail, and it is deemed sufficient for all intentions and purposes herein contained to show only portions thereof adjacent to and cooperating with the refrigerant drier and the refrigerant drier arrangement contemplated herein. It is to be understood that details of construction of such refrigerating systems with which the refrigerant drier arrangement contemplated herein may advantageously be employed, and/or their associated parts, may be modified to suit particular conditions or to satisfy the engineering genius of various manufacturers, and I do not Wish to be limited to the construction of these elements as set forth except where such construction particularly concerns the invention contemplated herein.

Having thus described, by way of example, a possible adaptation of the refrigerant drier and the refrigerant drier arrangement generally indicated at 20 and as contemplated herein, and having described the general environment surrounding the adaptation, the specific construction and cooperative functions of the parts of said refrigerant drier and refrigerant drier arrangement with which thepresent invention is particularly concerned, will now be described in detail.

In the exemplary embodiment of the invention depicted in Figs. 2, 3, 4 and 5," the refrigerant drier arrangement 26 with which the present invention is particularly concerned comprises, in general, a welded steel evaporator generally indicated at 40, said evaporator being formed to define a header 4! from which a series of serpentine channels 42 are opened'therefrom, said header silica-gel which has been proven very deficient for the purposes and intentions desired. For example, where cloth bags containing silica-gel "are disposed within the evaporator proper such cloth bags are subject to Weld burns'when the evaporator is welded or when extremeheat is applied to .adjacent parts during assembly and welding 4| and said serpentine channels being arranged to receive a suitable refrigerant, and a drier body 45 formed to define a cylindrical shape and arranged to retain a hydrophilic adsorbing agent 46 (Fig. 5) such as, for example, si1ica-gel, said drier body being secured to the inside portions of the header by means of a bracket 41 the ends of which are welded to the inner lining of the header 4|, said arrangement being particularly characterized in that the drier proper isdisposed in the header and submerged in the. refrigerant flowing through the header where the drier will be in a proper position to effectively adsorb objectionable moisture contained in the refrigerant.

Adverting to Fig. 5, it can be seen that the drier body may be formed out of copper tubing to define the shape as illustrated. Particular attention is directed to the fact that portions of the drier body 45 are crimpedadjacent the ends thereof to define stops 5!! and 5| which are arranged to prevent inward movement of end cap filters 52 and 53, respectively. The end cap filters are formed of minute copper pellets and impregnated with suitable adhesive substances to define the shape as illustrated and to retain the end cap filters in position. v

In manufacturing the drier body it is important to understand that the first step is to cut the proper length from a copper tubing. Thereafter, the crimps 50 and 5| .areforrned and the silicagel is placed within the container. The end cap filters 52 and 53' are placed in position and the ends of the drier body asat 60 and'fil arelspun so that the filters ,52, and 53 are securelyheld in their proper position. j

After the drier body is before described,'the drier body "45 is securely held in position in the header by means of the bracket 41, the end portions 48 and 49 of which may be welded to the innerlining of the header 4|. It is'important to note that the ends of the drier body are free so that refrigerant may flow into the drier body and into contact with the silica-gel whereupon any moisture contained in the refrigerant will be adsorbed by the silica-gel.

It isrecognized that in. some priorart structures it was suggested that the drier could be made a part of the evaporator proper. In such proposals cloth bags were employed to retain the assembled as herein 4 operations. In many cases it was found that these burns in the cloth bag weakened the struc-' ture of such bags and permitted thesilica-gel to flow out into the refrigeratingsystem-with the obvious result of'causing damage 'to the various parts of the refrigerating system.

Before being placed intoservice, the drier body 45 is filled with a suitable activated drying or water removing agent as hereinbefore described. Such an agent may be silica-gel, which is understood to be a colloidal form of silica prepared by coagulation of silica-hydrosol and subsequent dehydration. -This material is presently available in quantities and, when activated, possesses the property ofpreferentially adsorbing water from organic solvents such as refrigerants or lubricating oils. Moreover, the silica-gel in its present form possesses all of the necessary characteristics of a hydrophilic adsorber.

' Having thus described the general constructive features of the refrigerant drier and the refrigerant drier arrangement as contemplated herein, the general operation of the device will now be explained. In most refrigerating systems presentlybeingemployed a refrigerant called Freon (dichlorodifiuoromethane, CC12F2) is employed. Accordingly, the Freon refrigerant will be taken as a suificient example of the working fluid in the circuit, and silica-gel will be taken as the dehydrating agent. It is' well known in the art that Freon has many advantages as a refrigerant; however, with such advantages there is the attendant disadvantage in the Freon refriger-- ants are capable of dissolving enough water to cause trouble in a refrigerating system, the solu-- bility of the water being as much as two hundred parts per million atlOO degrees Fahrenheit, and sixty parts per million at freezing temperature, or 32 degrees Fahrenheit.

It is obvious that if the refrigerant is charged into the system on a warm day,or if through some inadvertence the apparatus is not adequately dehydrated at the factory, enough water may be contained in the refrigerant toseparate when the wet refrigerant flows through the capillary tube with concurrent cooling. This is particularly true inrefrigerating systems employing capillary tubes, because the separating water is apt to freeze in thesmall bore of such capillary tubes, thus plugging the system and leading to a service failure.

Since most refrigerating systems being presently employed containin the system a'hermetically sealed type compresson the effect of freezing in or adjacent the capillary tubes is sub-v stantially' aggravated. A situation of this type will start a cycle of events, that is to say, the plugging of the capillaries dueto freezing will make the compressor work harder whichresults in overheating of the motor-and, whenthe motor porated drying elements to eliminate moisture but their location has been on the high side of the circuit. All of the deficiencies of such a location for a drier are well known and need not be further discussed here except to say that the dehydrating agent such as silica-gel, is subjected to compressed refrigerant at relatively high temperatures when the drier is disposed in the high side of the circuit, these temperatures varying between 100 degrees to 200 degrees Fahrenheit. It is well known that it is not until the refrigerant passes through the capillary or restrictor and into the evaporator that significantly lower temperatures occur.

Moreover, at high temperatures, the silica-gel has a comparatively low power to adsorb or accept the moisture from the refrigerant since it is well known that the dehydrating property of silica-gel decreases with a rise in temperature and with the proportionate amount adsorbed. More important, it is notable that as the temperature of the silica-gel is increased, the partial pressure of the moisture taken up thereby is also increased, with the result that some of the adsorbed moisture in the drier may be released into the system when conditions change. This is particularly true when the drier element is disposed directly in the circuit, that is to say, in a manner whereby the refrigerant is caused to flow continuously and directly through the drier element.

Adverting to Fig. 2, it can be seen that the drier body 45 is positioned in the header 4! of the evaporator 40 and is submerged in the refrigerant passing through the header. refrigerant flowing into the header has previously passed through the capillary 21 and is in its expanded form. Accordingly, as the refrigerant emerges from the capillary tube 21 and into the evaporator header 4|, it expands and proportionally undergoes a reduction of temperature. The energy of the refrigerant accordingly cools the silica-gel 46 contained in the drier body 45 and this action automatically conditions the silica-gel so that its capacity to adsorb any entrained moisture is greatly increased.

Particular attention is directed to the fact that the solubility of the moisture in the refrigerant is decreased in practising the technique of this invention and the ability of the dehydrating agent to take up moisture is increased in a manner so that when the system is operating with a temperature adjacent the capillary tube close to freezing, the residual moisture content in the Freon can be reduced to a value of less than five parts per million. Moreover, it is important to note that because the drier body 45 is continually exposed to these low temperatures, re-solution of the adsorbed moisture is practically impossible.

From the explanation previously given, it will be observed that the temperature within the drier body 45 is quite low and may be considerably below 32 degrees Fahrenheit. Accordingly, the moisture content of the entire system can thus be reduced to the aforesaid value of around five parts per million, which leaves too little residual moisture ever to freeze up in the capillary tube 21. This is particularly true because such a small percentage of water is soluble in the refrigerant at any of the normal temperatures which will be encountered during operation of the system.

It is extremely important to note the particular advantage of submerging the drier in the Thus, the g refrigerant disposed in the header of the evaporator as contrasted with installing the drier in the circuit where the refrigerant is required to constantly pass through the drier body in order to complete its circuit. By submerging the drier body in the refrigerant moisture previously adsorbed can never be forced out of the drier and into the system.

From the foregoing disclosure, it may be seen that'I have provided an improved refrigerant drier and refrigerant drier arrangement which provides improvements in constructions eilective to increase the dehydrating effect of a given quantity of hydrophilic adsorbent by disposing the adsorbent in the header of the evaporator and submerging the same in the refrigerant flowing through the header, that portion of the refrigerating cycle being subjected to avery low temperature, thereby to increase the effectiveness of the adsorbing characteristics of the hydrophilic adsorbent. Moreover, it can be seen that I have provided an improved refrigerant drier and refrigerant drier arrangement which efficiently fulfills the objects thereof as hereinbefore set forth and which provides numerous advantages which may be summarized as follows:

l. structurally simple, efdcient and durable;

2. Economical to manufacture and readily adaptable to mass production manufacturing principles; and

3. The provision of a refrigerant drier submerged in the refrigerant disposed in the low side of a refrigerating system and more particularly, submerging the drier in the refrigerant passing through the header of the evaporator of a refrigerating system.

While I have illustrated preferred embodiments of the invention, many modifications may be made without departing from the spirit of the invention and I do not wish to be limited to the precise details of construction set forth, but wish to avail myself of all changes within the scope of the appended claims.

I claim:

1. In a refrigerating apparatus comprising a compressor, condenser, refrigerant expansion device, and a header for an evaporator connected in a closed cyclic path and in the order named, said evaporator having a series of channels opening from said evaporator header and said refrigerating apparatus including a suction line connecting the end of said series of channels removed from the header to said compressor to complete the system, and a charge of refrigerant in the apparatus, those improvements comprismg a non-porous drier body formed to define a cylindrical shape and arranged to encase and retain a hydrophilic adsorbing agent, said drier body having filters mounted within the casing and transversely thereof adjacent each end, said drier body being arranged to be disposed in the header in the low pressure side of the refrigerating apparatus adjacent the opening where the refrigerant is received into the header of the evaporator and submerged in the refrigerant where the operating temperatures of the system are at their lowest as distinguished from connecting the drier body in the circuit formed by the refrigerating apparatus where the refrigerant is forced to fiow through the drier to complete its circuit, and the adsorption of objectionable moisture being responsive to subjection of the refrigerant to the hydrophilic adsorbent at substantially the lowest operating temperature in the system. I

2. Drying apparatus for a refrigerating system comprising a restrictor device and an evaporator having a header arranged to receive refrigerant discharged from said restrictor device before passing through the evaporator, non-porous tubular shaped casing means in the header in the low pressure side of the refrigerating system adjacent the opening where the refrigerant is received into the header of the evaporator and submerged in the refrigerant where the operating temperatures of the system are at their lowest as distinguished from connecting the drier. in the circuit formed by the refrigerating system Where the refrigerant is forced to flow through the drier to complete its circuit, said casing means having filter means mounted at each end thereof and said casing means including said filter means being arranged to encase and retain a hydrophilic adsorbing agent, and the adsorption of objectionable moisture being responsive to subjection of the refrigerant to the hydrophilic adsorbent through said filter means at each end of said casing means at substantially the lowest operating temperature in the system.

3. A refrigerating apparatus comprising a compressor, condenser, restrictor device, first refrigerant expansion device at the discharge side of said restrictor device, an evaporator header, and a second refrigerant expansion device defining an evaporator having a series of serpentine channels discharging into the low side of 10 said compressor; said compressor, condenser, restrictor device, first refrigerant expansion device, evaporator header, and second refrigerant expansion device being connected in a closed cyclic path and in the order named; a charge of refrigerant in the apparatus; and a non-porous drier body formed to define a cylindrical shape and arranged to retain a hydrophilic adsorbing agent, said drier body having filters mounted therein and transversely thereof adjacent each end, said drier body being carried by inside portions of the header in the low pressure side of the refrigerating apparatus adjacent the opening where refrigerant is received into the header, said arrangement being particularly characterized in that the drier proper is disposed in the header of the evaporator and submerged in the refrigerant flowing therethrough whereby the hydrophilic adsorbent material will have an increased capacity for water adsorption at operating temperatures existing adjacent the header of the evaporator to effectively adsorb objectionable moisture contained in the refrigerant.

EARL F. HUBACKER.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,809,833 Davenport June 16, 1931 2,430,692 Touborg Nov. 11, 1947 2,548,335 Balogh Apr. 10, 1951

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