US2166190A - Condenser arrangement - Google Patents

Description

July 18, 1939. L. F. WHITNEY v v ,1

CONDENSER ARRANGEMENT Filed Oct. 29, 1957 Patented July 18, 1939 UNITED STATES PATENT. OFFICE CONDENSER ARRANGEMENT Application October 29, 1937, Serial No. 171,647

15 Claims. (01. 62-115) This invention relates to animproved condenser arrangement, and particularly to a compact arrangement of this character which may be employed in a refrigerating system, such, for example, as a system of the character disclosed in United States Patent No. 1,761,551 to Eastman A. Weaver.

It is often desirable to provide a compact condenser which may, for example, be installed in the upper part of a household" refrigerator housing without objectionably increasing the height of the housing.

A condenser of the type to which the present invention is directed must be arranged to drain condensed liquid to a suitable outlet or outlets. Such acondenser may comprise a single condensing duct into and through which vapor passes; such a duct should have a general inclination to facilitate drainage of the condensate and to prevent collecting of the same in portions of the duct. For example, in refrigerating systerns of the character referred to, it appears desirable to have the duct provided with a general inclination at least of the' order of 5. On the ,other. hand, it is desirable to have a relatively long duct or passage to afford adequate cooling capacity, particularly when air cooling is employed and the duct is provided with cooling fins or the like, I

If an elongate duct having a continuous inclination of the order named is provided for the condenser, the total height of the condenser will be greater than is desirable in many household installations. Accordingly the present invention affords an arrangement of the condenser. duct with successive sections having an inclination at least of the order named, so that the duct may have an adequate length to afford proper cooling capacity, while being arranged to afiord compactness.

To permit these desirable results, the duct preferably comprises successive sections which are slightly inclined from the horizontal and which are substantially parallel to each other. Thus the condenser duct may comprise a first section which is upwardly inclined from the lower side or end to the upper side or end of the condenser, the duct being continuedin a second section inclining downwardly in general parallelism' to the first section, a third section. preferably being connected to the second section and inclined upwardly in substantial parallelism to the first two sections, and a fourth section iii-- clining downwardly and being substantially parl allel to the first three sections. Thus the condenser duct may be arranged so that the condenser does not have an objectionable height or vertical dimension, while the pipe sections are arranged in general side-by-side relation, so that the condenser may have horizontal dimensions permitting its ready installation in a conven- 'tional refrigerator cabinet.

In order to permit the arrangement of the duct sections in this manner and yet to avoid pocketing of the condensate at the lowerend of the condenser, drains are provided communicating with the lower ends of each of the duct sections, so that condensate from any part of the condenser may be received by one or the other drains. Suchdrains communicate with a common outlet or condensate receiving pipe which directs the condensed refrigerant from the condenser back tothe cooler or evaporator. Such an arrangement without' further qualification would be unsatisfactory when non-condensable gases are received in the condenser; such gases would tend to pocket in the condenser cluct and the vapor would pass directly from one drain to another rather than flowingthrough each of the successive duct sections.

In order to prevent such undesirable results, trap means is provided to prevent the flow of vapor from one drain directly into another drain, although this meanspermits the flow of condensate from each drain 'to the common receiv ing pipe. Thus the vapor received by the condenser passes in succession through each of the condenser sections until it is liquefied, while the condensate may flow from each section to the corresponding drain and from the latter to the common receiving pipe.

A condenser of this general type may also conveniently be provided with a drum connect ed to the last section or connected to the end of the condenser remote from the vapor inlet, this drum having a substantial volumetric capacity and thereby increasing the total effective volume ,Of the condenser so that substantial changes in the temperature of the condenser duct do not result from theappearance of non-condensable gases in the system. Furthermore, such a drum or chamber aids the separation of the non-condensable gases from the vapor.

A system in which a condenser of this type is employed may operate at low pressures and may be provided with a purger of the type disclosed in the United States patent to Daniel F. Com-.

stock No. 1,892,869, issued January 3, 1933. Such a purger is arrangeckto receive non-condensable gases from the condenser, and to exhaust the ularly advantageous when freezing occurs in the refrigerant return pipe between the condenser and evaporator. Under such conditions it is desirable that the condensate collect in the condenser without overflowing from the same and returning in liquid form to the region of the pumping means or aspirator, which might result in the formation of an undesirable sludge. Thus, for example, when water alone is employed as the refrigerant, the condenser may have a liquid capacity suflicient to receive all of the refrigerant in the system, while when an anti-freeze agent is employed,- the liquid-con taining capacity of the condenser may be made somewhat smaller.

In the accompanying drawing:

Fig. 1 is a diagrammatic view of a refrigerating system provided with a condenser arrangement of the character afforded by the present invention, the condenser assembly being shown by an isometric disclosure;

Fig. 2 is a plan view of the condenser assembly and related parts;

Fig. 3 is a view, partly in section and partly in elevation, of the trap assembly which is asso-- ciated with the condenser; and

Fig. 4 is an elevational detail of a portion of the condenser including the drum and the trap assembly.

While a condenser arrangement of the character disclosed herein may be employed in different environments for various purposes, it is particularly useful when employed with a refrigerating apparatus of the character disclosed in the above-identified patents. Such an apparatus is diagrammatically shown in Fig. 1 and includes a boiler I provided with a heating element 2 such as an electrical resistance factor. The boiler I may contain a body of heavy propellant, such as mercury. During normal operation mercury vapor flows from the boiler I through the riser.

3 to the aspirator nozzle 4, from which the mercury vapor passes at high velocity into the mixing chamber 5. The latter is connected by a vapor duct 6 to a cooler I which contains a body of liquid refrigerant such as water or a mixture of water and a suitable anti-freeze ingredient such, for example, as the mono methyl ether of ethylene glycol. The propellant vapor draws refrigerant vapor from the cooler 1 through the pipe 6 into the mixing chamber 5. The mixed vapors pass into the funnel I where the refrigerant vapor is compressed and propellant vapox is condensed, suitable cooling fins, II or the like being provided to aid the condensation of the propellant vapor. The compressed refrigerant vapor passes through a duct l2 to a condenser 20 which may be disposed at the upper part of the system, while the condensed propellant is received by a drain M which is continued as one leg of a mercury containing trap Hi, the opposite leg of the latter being connected to the drop tube l6 of a purger, which receives non-condensable gases through a supply duct H.

The non-condensable gases are compressed by propellant globules dropping through the tube It as more fully disclosed in the above-identified patent to Daniel F. Comstock, the compressed gas being exhausted from the system through the well or vat l8 and the propellant liquid rising from the lower part of the purger through the duct I9 to a spill-over connection with the pipe 22 which is connected to the duct 23 leading back to the lower part of the boiler. The upper end of the duct 23 may conveniently be connected to the mixing chamber to receive condensed propellant particles from the same. A column of the liquid propellant in the return duct 23 balances the boiler pressure.

A duct 21 is provided with a trap 28 to receive propellant from the cooler I so that stray propellant particles may return from this portion of the system to the duct 22 and thence to the boiler I.

The condenser assembly, which more particularly forms the subject matter of the-present invention, may conveniently comprise a condenser duct which affords a continuation of the vapor duct |2. This condenser duct is provided with a plurality of sections which have a slight inclination from the low to the high end of the condenser. Thus the first section 3| has its upper end connected by a U-shaped pipe portion 3| to the second section 32, the latter being connected by a similar connection 32 to the third section 33, which in turn is connected by a U- shaped connection 33 to a fourth section 34. The duct sections 3|, 32, 33 and 34 may be disposed substantially parallel to each other and may each have a moderate inclination. In other words, each of the pipe sections and the U-shaped connections therebetween may lie in a common inclined plane. Each of the sections 3|, 32, 33 and 34 is provided with a plurality of cooling fins 36. 1

It is evident that vapor received from the vapor inlet pipe l2 will pass into the first section 3|, flowing through this section from the lower to the upper end of the condenser, thence through the connection 3| into the second section 32, through which the vapor will flow downwardly toward the lower end of the condenser, being received by the connection 32. From the latter the vapor flows through the third section 33 from which the vapor passes through the connection 33 into the fourth downwardly inclined section 34. A suitable drum or receptacle 40 may be connected to the end of the last section 34, the gasreceiving tube ll extending downwardly into this drum and having an open end therein. Drum 4|! preferably has a volumetric capacity greater than that of the duct. The volumetric capacity of the condenser including the drum may thus be readily made greater than the capacity of the cooler, if desired, so that the condenser may be able to contain all or a substantial portion of the liquid refrigerant included in the system.

In order to avoid pocketing of liquid in the lower portions of the condenser, drains are provided to receive condensate from the lower end of each duct section. Thus a drain 42 is connected to the lower end of the duct section 3|, while a drain 43 is connected to the U-shaped pipe portion 32 at the lower ends of pipe sections 32 and 33. A third drain 44 communicates with the bottom of the drum 40, thus being arranged to receive condensate drained from the fourth section 34 into the drum.

The drains 42, 43 and 44 are arranged to supply the liquefled refrigerant to a common receiving pipe 46 which is provided with a trap 41 to hold a body of pressure balancing liquid, the

I side wall of which isconnected to the open end of the drain 44 (Fig. 3). The drain 4! extends downwardly into the receptacle and has an .open end in the lower part of the same, while the receiving pipe 46 has an open end communicating with the interior of the receptacle between its upper and lower walls, the drain 43 conveniently communicating with the pipe 46 outside of the trap 50; The trap 50 contains a liquid body 51,, e. g., mercury, in which the lower end of the pipe 42 and the end of pipe 44 are immersed; the pipe 48 having a general downward inclination so that the level of the mercury in the cylindrical recep--' tacle is even with the connection to this pipe.

is in operation, some mercury particles stray from the funnel ilfl through the pipe lz-to the condenser 20 where these particles are condensed. Some oi these particles are receivedby the drains 42 and 4d, the remainder thereof being received by the drain 43. The particles received by the first-named drains pass .into the cylindrical receptacle so that the -heavy'liquid body 51 is always maintained in this receptacle. On the other hand, when the mercury tends to pile up in the receptacle above its connection with the pipe 46, the mercury overflows into this pipe and drains to the trap 41. If the mercury in this trap overflows, it is received by the cooler I and then by the trap 28, irom which the mercury passes through the pipe 21 to the ducts 22 and 23 and thus back to the boiler. Condensed mercury received by the drain 43 passes directly to the pipe 46 and may similarly return from the latter to the boiler.

It is thus evident that the mercury body 51 is automatically maintained at the desired height in the trap 50. Accordingly when the condensed refrigerant is received from thedrain 42, it rises to the top of the mercury body 51 and overflows into the receiving duct 46. Similarly condensate from the drain 44 rises to the top of the mercury body and passes into the pipe 46, while obviously condensate from the drain 43 is directly received by the pipe 46. a

The body of liquid mercury in the trap affords a seal preventing the direct flow of refrigerant vapor between any of the drains 42, 43 and 44.

.Accordingly vapor can not flow directly from the lower end of one drain to that oi. another and the main vapor stream passes by the drains and goes through the successive duct sections where condensation occurs. The non-condensable gases which may appear in the system are pumped into the-condenser duct; the vapor passing through the duct sweeps tnese gases into the drum 40, from which they are drawn through the tube I! to the purger. were the trap 50 not provided, non-condensable gases present in the vapor stream would be pocketed in the U-shaped duct portions, thus materially reducing the efficiency oi the condenser.

The drum 40 may have an adequate volume substantially to increase the total volumetric capacity oi the condenser, for example, a volume at least nearly as great as that of the condenser pumps theg'ases to the drum; the downward inclination' or the duct section" 34 also aids the movement of the gases from this part of the condenser to the drum. The drum ordinarily v.may contain a body oi non-condensable gas I mixed with refrigerant vapor, the pressure of this vapor being less than that of the vapor in the duct and the temperature of the drum being lower than that of the duct. Thus little condensation is taking place in the drum and there I! is no necessity of providing this part or the condenser with nns.

. As shown in Fig. 4, the drum ll may have a downwardly inclined lower wall, thus providing.

'aj'lower portion in which the non-condensabie ltS gases, which are generally heavier than the vapor, may collect, it being evident that the open end oi" tube I1 .is disposed adjoining this lower part of the drum, and that this part of -thedrum is below the adjoining 'part of the contil When a system of the type. shown in.Fig. 1

denser duct. Such an arrangement permits a.

larger proportion of gas to be included in the therein may be lower than the temperature of the condenser duct. Accordingly the pressure oi the refrigerant vapor in the drum may be 8 substantially lower than the pressure of the reirigerant vapor in the condenser duct. Since I the total pressures of the vapor-gas mixtures in the duct and drum must be substantially the same, the proportion of non-condensable gases as is greater in the drum. Accordingly the mixture which is being supplied to the purger is relatively rich in gas and weal: in vapor. Thus while some of the vapor may be exhausted by the purger,

the amount of vapor thus exhausted is negligible 0 even over a very long period of time.

Under'actual operating conditions the drum may contain non-condensable gases which, were the drum not provided, would fill a portion of the condenser duct and thus reduce the length a of the duct then eflfective to cause condensation of the refrigerant vapor. Due to the increased volumetric capacity of the condenser resulting from the use oi the drum, a given quantity of gas does not'have such a tendency to require M an increase in pressure and temperature in the condenser as would be the case were the drum to be omitted.

It is thus apparent that the arrangement of the drum or'chamber 40 permits the condenser 55 to be compact and yet to have adequate volumetric capacity so that it is less sensitive to the leakage oi nori-condensable gases than would otherwise be the case. The collection or the gases in the drum is due both to gravity and to so the sweeping action of the vapor stream, while, due to gravity, the mixture in the drum itself is especially rich in gases adjoining the inlet of the purger supply tube l'l.

Furthermore, it is desirable to have a con- 06 denser of adequate capacity to retain all of the liquid refrigerant pumped thereto when freezing occurs in the pipe 46 between the trap 41 and the cooler and thus prevents the normal flow Under these of refrigerant back' to the cooler. conditions the system will continue to withdraw refrigerant from the cooler and pump the same to the condenser where condensate will collect. It a refrigerant such as substantial pure water is employed in the cooler, substantia all of the I refrigerant may thus be pumped to the condenser which, under these conditions, should have a liquid capacity sufficient to contain substantially all of the refrigerant in the system without allowing the same to overflow from the condenser and return through the pipe I! to the lower end of funnel it). Such a movement of the liquid refrigerant might result in an interaction of-the mercury and refrigerant to form sludge, such a sludge substantially impairing the effectiveness of the system as more particularly described in my copending application Serial No. 171,325, filed October 2'7, 1937.

When refrigerant including an anti-freeze agent such as methyl cellosolve is employed in a system of this character and freezing occurs in the pipe 46, the aspirator will continue to withdraw refrigerant vapor from the cooler, thus causing the COHECtiOIl of liquid refrigerant in the condenser. However, since the anti-freeze agent, e. g., methyl cellosolve, is less volatile than water, the aspirator is not so effective in pumping vapor from the refrigerant solution in the cooler and this solution becomes richer and richer in anti-freeze.

Eventually a condition of equilibrium is reached, so that little more vapor can be pumped,

by the aspirator, although some relatively rich solution remains in the evaporator. Accordingly it is evident that when an anti-freeze agent which is less volatile than water is employed in a system of this character, the liquid capacity of the condenser need not be as great as would be desirable when pure water is employed as the refrigerant. It is sufficient, in a system employing such an anti-freeze agent, to provide a condenser having adequate capacity to retain all of the refrigerant that would be pumped thereto before the system reached the condition of equilibrium just described.

When freezing occurs in the return duct 46 and the refrigerant collects in the drum 40, the open end of the tube I] may be immersed in the liquid refrigerant. Under such conditions and without further qualification, the purger would then be effective in pumping liquid refrigerant out of the system, which obviously would'be undesirable. In order to prevent such a result the tube ll adjoining the upper wall of the drum to is arranged in the general manner disclosed in the copending application of Eastman A. Weaver, Serial No, 168,961, flied October 14, 1937, the tube being provided with a vent or opening 10, and a wire H preferably is welded to the tube and extends diametrically across the opening. Thus when the lower part of the drum is filled with.

liquid refrigerant and the lower end of the tube is immersed in this liquid, the purger can continue to'withdraw non-condensable gases from the system through the vent III, as more fully disclosed in the above-identified Weaver application. During normal operating conditions the vent I0 is closed by a body of the liquid condensate so that non-condensable gases then only enter the tube I! through the lower open end thereof.

It is evident that the present invention, which provides a compact arrangement of a condenser duct, is particularly advantageous with an aircooled condenser for a refrigerating system, permitting the compact installation of the condenser in the upper part of a refrigerator housing, while permitting the ready drainage of liquid from all parts of the condenser and avoiding pocketing of liquid or non-condensable gases in the same.

Furthermore, the present invention provides a condenser which has relatively high efficiency and yet suflicient volumetric capacity so that it is not unduly sensitive to the leakage of non-condensable gases into the system either from the metal of the walls thereof or from the exterior atmosphere. The provision of the drum permits the compact condenser with its relatively smalldiametered condenser duct to have adequate capacity to receive all of the liquid refrigerant in the system. Accordingly, even when non-condensable gases collect in the system slightly faster than they are being exhausted by the purger, the system can continue to operate for a long period of time without an undue rise in the temperature and pressure of the condenser,

It should be understood that the present disclosure is for the purpose of illustration only and that this invention includes all modifications and equivalents which fall within the scope of the appended claims.

I claim:

1. A condenser comprising a duct having a vapor-receiving inlet, a section of the duct having a general inclination upwardly from the region of the inlet to a higher region, a second section of the duct communicating with the first section in said higher region and inclining downwardly to a point near the level of said inlet, and drain pipes communicating with the lower ends of each of said sections to receive condensate therefrom.

2. A condenser comprising a duct having a vapor-receiving inlet, a section of the duct having a general inclination upwardly from the region of the inlet to a higher region, a second section of the duct communicating with the first section in said higher region and inclining downwardly therefrom, drains communicating respectively with the lower ends of each of said sections to receive condensate therefrom, a receiving pipe connected to said drains, and trap means preventing direct flow of vapor from one drain to the other drain while permitting con-- densate from both of said drainsto be received by said receiving pipe.

3. A condenser comprising a duct having at least four similarly inclined sections, the first section having a vapor inlet at its lower end and communicating at its upper end with the upper end of the second section, the third section communicating at its lower end with the lower end of the second section and at its upper end with the upper end of the fourth section, drains com- -municating with the lower ends of each of said sections to receive condensate therefrom, a liquid containing trap connected to at least two of the drains and arranged to prevent direct flow of vapor from one drain to another drain, but to permit the flow of condensate from the drains, and a collecting pipe to receive said condensate from the trap and drains,

4. A condenser comprising a duct having, at least four similarly inclined sections, the first section having a vaporinlet at its lower end and communicating at its upper end with the upper end of the second section, the third section co'mmunicating at its lower end with the lower end of the second section and at its upper end with the upper end of the fourth section, a drain connected to the lower end of the first section to receive condensate therefrom, a second drain connected to the lower ends of the second and third sections, a third drain connected to the lower end of the fourth section, a trap containing a 2,166,1 oo body of liquid, the first and one of the other drains having outlets in said trap below the surface of said body of liquid, a collecting pipe connected to said trap above the level of said body of liquid and connected to the third drain, whereby vapor is prevented from flowing directly from one drain to another drain.

5. A condenser comprising a duct having a plurality of similarly inclined straight sections, the first section having a vapor inlet at its lower end, the successive sections being connected to each other by substantially U-shaped portions of the duct, said straight sections and u-shaped portions being substantially disposed in a common inclined plane, whereby vapor passes upwardly and down-- wardly through successive sections of the duct, drains communicating with the lower end of each section to receive condensate therefrom and from the lJ-shaped portions, a common receiving pipe to which the condensate is directed from said drains, and a liquid-containing trap communicating with the .drains and pipe, said trap permitting the flow of condensate from said drains'to the pipe, but preventing the flow of vapor directly from one drain to another drain. 6. A system of the class described employing.

the vapor of a heavy propellant which pumps refrigerant vapor from a cooler to a condenser, said system having means to condense the major portion of the propellant while supplying the pumped refrigerant vapor with stray propellant particles to the condenser, said condenser comprising a duct having a plurality of similari y inclined sections, the first section having an inlet at its lower end to receive thepumped refrigerant vapor and stray propellant particles, the successive sections of the condenser being substantially disposed in a common inclined plane, drains communicating with the lower end of each of said sections to re-= ceive condensate therefrom, a common receiving pipe to which the condensate is directed from said drains, a liquid-containing trap communicating with the drains and pipe, said trap containing a body of the heavy-propellant liquid and being arranged to permit the flow of condensate from the drains to the pipe, but preventing the flow of vapor directly from one drain to another drain.

7. A condenser comprising av duct having at lease four similarly inclined sections, the first section having a vapor inlet at its lower end and communicating at its upper end with the upper end of the second section, the third section communicating at its lower end with the lower end of the second section and at its upper end with the upper end of the fourth section, drains communicating with the lower ends of each of said sections to receive condensate therefrom, a liquidcontaining trap connected to at least two of the drains and arranged to prevent direct flow of vapor from one drain to another drain, but to permit the flow of condensate from the draine a collecting pipe to receive said condensate from the ,trap and drains, and a chamber connected to the end of said fourth section to receive non-condensable gases.

8. A condenser comprising an elongate condensing duct of relatively small diameter, cooling means associated with the duct, said duct having an inlet end to receive ccndensable vapor, a chamber having a connection with the end of said duct remote from said inlet, said chamber having a portion at a lower level than that of its connection to said duct, portion, whereby non-condensable gases may be swept by the vapor stream to said chamber, and the mixture of vapor and gases in said chamber portion may be richer in said gases due to the different weights of the vapor and gases, and a gas outlet pipe communieating with said chamberportion.

9. A condenser comprising an elongate condensing duct, cooling fins associated with said duct, said duct having an inlet to receive condensable vapor, a chamber, a connection between said chamber and the end of the duct remote from its inlet, said chamber being free from fins and having a portion at a lower level than that of said connection, said portion being arranged so that a mixture of vapor and non-condensable gases which is relatively rich in the gases may pocket therein due to the different weights of the vapor and gases, and a gas outlet pipe communicating with said portion of the chamber at a level substantially lower than said connection with the duct, whereby a mixture rich in gas may be pocketed in said chamber portion and preferentially supplied to said outlet pipe.

10. A system of the class described, comprising a refrigerant circuit including a cooler and a condenser, said condenser receiving refrigerant vapor and non-condensable gas which has a weight greater than that of the vapor, said condenser comprising a condensing duct portion having an inlet end, and a gas collecting chamber having a connection with the opposite end of the duct portion, the major portion of the chamber being disposed at a level lower than the connection to said duct portion, whereby a mixture of vapor and gas which is relatively rich in gas collects in said portion'of the chamber.

11. A system of the class described comprising a. refrigerant circuit including a cooler and a condenser, said condenser receiving refrigerant vapor and non-condensable gas which has a weight greater than that of the vapor, said condenser comprising a condensing duct portion having an inlet end and a gas collecting chamber having a connection with the opposite end of the duct portion, said chamber having a volume which is at least substantially as large as that of the duct portion, the major portion of the chamber being disposed below its connection torsaid duct portion, whereby a mixture of vapor and gas which is rela-' tively rich in gas coliects'in said portion of thechamber, and a purger connected to the lower portion of the chamber to receive non-condemsable gases therefrom.

12. A low pressure system or the class described employing the vapor of a heavy propellant to pump refrigerant vapor from a cooler to a condenser, said system having means to condense the major portion of the propellant While'supplying the pumped refrigerant vapor with stray pro-- pellant particles to the condenser, said system also having a purger wherein condensed pro-- pellant pumps non-condensable gases from the condenser, said condenser comprisinga duct having a plurality of similarly inclined sections, the first section having an inlet at its lower end to receive the pumped refrigerant vapor and stray propellant particles, drains communicating with the end of the condenser duct remote from its inlet end, said drum havinga volumetric capacity greater than that of the duct and having its major portion disposed ata level below its connection to the duct, a tube connecting the lower portion of said drum to the purger so that a mixture rich in non-condensable gases may be supplied from the condenser to the purger.

13. A low pressure system of the class described employing the vapor of a heavy propellant to pump refrigerant vapor from a cooler to a condenser, said system having means to condense the major portion of the propellant while supplying the pumped refrigerant vapor with stray propellant particles to the condenser, said system,

also having a purger wherein condensed propellant pumps non-condensable gases from the condenser, said condenser comprising a duct having a plurality of similarly inclined sections, the first section having an inlet at its lower end to receive the pumped refrigerant vapor and stray propellant particles, drains communicating with the lower ends of the sections to receive condensate therefrom, a common receiving pipe to which the condensate is directed from said drains, a trap communicating with the drains and pipe and containing a body of the heavy propellant liquid, said trap being arranged to permit the flow of condensate from the drains to the pipe but preventing the flow of vapor directly from one drain to another drain, and a drum connected to the end of the condenser duct remote from its inlet end, said drum having a volumetric capacity greater than that of the duct and having its major portion disposed at a level below its connection to the duct, a tube connecting the lower portion of said drum to the purger so that a mixture rich in non-condensable gases may be supplied from the condenser to the purger, said condenser having a volumetric capacity suflicient to receive all of the liquid refrigerant in the system so that the refrigerant may be contained in the condenser when refrigerant freezing in the receiving pipe prevents the normal circulation of the refrigerant through the system.

14. Refrigerating apparatus of the class described comprising a propellant circuit and a refrigerant circuit including a condenser, a cooler,

and a pipe connecting the condenser to the cooler, said circuits having a part in common where propellant vapor entrains refrigerant vapor from the cooler and pumps the same to the condenser, said system also having a purger wherein condensed propellant pumps non-condensable gases from the condenser, said condenser including a condensing duct of relatively small diameter having an inlet end to receive vapor from the common part of the circuits, said condenser also including a drum with a relatively large volumetric capacity connected to the opposite end of the condenser duct, a tube to supply non-condensable gases from the drum to the purger, said condenser having a liquid-retaining capacity great enough to hold substantially all of the refrigerant pumped thereto when refrigerant freezes in the pipe between the condenser and the cooler, the drum providing a reservoir to receive non-condensable gases and permitting the condenser to have adequate volumetric capacity.

l5. Refrigerating apparatus of the class described comprising a propellant circuit and a refrigerant circuit having a part in common where propellant vapor pumps and compresses refrigerant vapor and where the propellant vapor is, condensed, said propellant circuit also including a boiler, a vapor pipe connecting the boiler to said common part, and a return pipe connecting said common part and the boiler, said refrigerant circuit also including a cooler and a refrigerant condenser with ducts connecting said common part to the refrigerant condenser, said condenser to the cooler, and the cooler to said common part, said refrigerant condenser having a liquid capacity large enough to hold all of the refrigerant in the system whereby, when freezing occurs in the duct connecting the condenser and cooler,- liquid refrigerant may collect in the condenser without flowing into the duct between said common part and the condenser.

LYMAN F. WHITNEY.

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