US2819592A

US2819592A - Accumulator heat exchanger

Info

Publication number: US2819592A
Application number: US274719A
Authority: US
Inventors: Sterling F Smith
Original assignee: Individual
Current assignee: Individual
Priority date: 1952-03-04
Filing date: 1952-03-04
Publication date: 1958-01-14
Anticipated expiration: 1975-01-14

Description

Jan. 14, 1958 s, SMITH ACCUMULATOR HEAT EXCHANGER Filed Maich 4, 1952 FIG. 1

4 Sheets-Sheet 1 FIG INVENTOR. STERLlNG F'- SMITH ATTORNEY Jan. 14, S. F. SMITH ACCUMULATOR HEAT EXCHANGER Filed March 4, 1952 4 Sheets-Sheet :2

4o 41 27 I3 l9 2| n 25 I6 IO 23 INVENTOR. STERLING F- SMWTH AT TORNEY Jan. 14, 1958 s. F. SMITH 2,319,592

ACCUMULATOR HEAT EXCHANGER Filed March 4, 1952 4 Sheets-Sheet 3 2713 IQZI ll I6! FIG. 7

32/ 44 f T 4 I n- 35 H4 H3 INVENTOR.

.' V STERLING F SMITH ATTORNEY Jan. 14, 1958 s. F. SMITH 2,819,592

ACCUMULATOR HEAT EXCHANGER Filed March 4, 1952 4 Sheets-Sheet 4 FIG.10b

FIG. 10

INVENTOR. STERLING E SMITH ATTORNEY United States swear ACCUMULATOR HEAT EXCHANGER St'eriin'gFi Smith,.Washi|igton, n. c;

ApplicationMarch 4, 1952, Serial No. 274 ,7151 5 Claims. or; 62 -11755) This invention relates to refrigeration and air, conditioning and more particularly to a combination accumulator-heat exchanger designed to improve the efiiciency of operationof a system and which will allow condition res'ponsive control components partieularly the refrigerant flow control and condenser cooling medium control) greater latitude of operation.

While the advantages of an accumulator or surge tank have been known, heretofore, as well as the general idea of heat exchange between the high pressure liquid and the suction side, the present invention provides an accumulator-heat exchanger combination which is particularly adapted to insure the precooli-ng of the super heated refrigerant leaving the discharge side of the compressor and which may be employed in the improvement of present methods of defrosting systems. V

The technical progress which has been made the refrigeration and air conditioningindustry in recent years has resulted in a tremendous increase in the installation of fully automatic refrigeration and air conditioningsysterns. In fact at the present time the system, operatjed under the supervision of an engineer is the exception rather than the rule. u The fully automatic system usually consists of a cornpression side and cooling coils controlled by various automatic devices which control in turn the: flow of liquid refrigerant to the cooling coils, the operating 'cycle of the compression equipment, and in a Water cooled System, the how of water through the condenser, Within the limitations of the control components it is possible to obtain a fairly balanced system under ordinary operating conditions. There is, however, a wide gap between the results obtained by such automatic control devices and those obtained by the operating engineer who"adjtists each one to meet the need as it develops.

This situation has led to a demand for othercofitr'ol vice would preferably accomplishdheseresulte Without requiring an increase in the energ inpumo the system.

his well knownthata refrigeration systemihasva relatively low efficiency ratio. This is due part-lytorthe. fact that mechanicalfriction andthemolecular friction of compression raise the temperature of Ethehisbharge gas above the temperature at which the gasmaycondense.

Also in unflooded evaporatorsa; portion ofthe: effective heat absorbing surface of the cooling co'il isfl lost'ihfdrying the refrigerant.

Accordingly, it is an object of the invention to pro- Patent 0 I? vide means for increasing the efficiency ratio or a refrigeration system by cooling the discharge gasto or near itscondensing temperature before it news to the condenser, without increasing the energy input to the system, through the use, in a water cooled system of the waste water of the condenser, or in an air cooled system by utilizing the high ratio of heat exchange between the ambient air and the discharge gas;

A further object is to provide a combination accumulator and heat exchanger useful as a basic accessory to improve the operation of a refrigeration or air conditioning system.

A further object is to provide a means of increasing the condensing capacity of the system, thus insuring against motor overload.

A further object is to provide a means of lowering the required motor input, thus reducing the operating cost, through lower head pressures made possibleby increased condenser capacity which ;is gained by passing super-heated gas from the compressor through the heat exchanger-accumulator A further object is to provide, through the operation of the combination accumulator-heat exchanger, means to insure that the refrigerant from the cooling coils is returned to :the compressor ,in a dry" state with maxi- ,mum ,efiective use of the cooling coils thus insuring .that

the compressor operates at maximum efiiciency for its operating back pressure without re-expansion ,occu rrfing in the compressor body or cylinders. A

.A.-fur,ther objectis to provide within theaccumulatorheat exchanger combination means to ,efhciently distribute heavily saturated refrigerant gas or liquid re- :frigerant flowing from the cooling Icoils, thus insuring rapid expansion and means for receiving theexp'anded refrigerant within the accumulator-heat exchanger in a manner to avoid short circuits there'within.

Afurther object of the inventionis tolprovide attaccurn'ulator-heat exchanger through the operationof hic h the system may be balanced ofr stabiliz ed, arld whereby, through regulation of the liquid refrigerantcontrol, the capacity of thecooling coils maybe adjusted to iisure maximum efficiency of the heatabsorbing -sur" without 'danger of flooding the system; fufther, the

capacity of the compressor maybe regulated by adjustment of means controlling the how or thecooling medium passing' throughtheheat exchanger in the accumulator.

A further object is to provide, within the accumulatorheat'exchanger, meansto insulate thehea'texchanget' to the desired degree to permit only the desired amountuof heat t (depending on the operating back, pressure) ;to be passed to the suction gas, the ,amount of heat-fiowing thereto being proportioned to the opera ing-back, pressure.

In a fluid defrosting system, whenthe temperature of the fluid is-below 50 degrees R, the defrosting action is .relativelyhineflicient. In such a system, heat and pressure applied: internally to the cooling, coils, increases" theefficiency of the defrosting action. 7

Accordingly, it is a further object of the invention to provide heating means for the defrosting fluid andmea ns for furnishing" warm refrigerant under pressure to, the internalsurface of the cooling coil.

A still further object is to providea 'refrige'r'atioh system adapted to operate athigh efficiency-within major components in balance, without the "use-of complexcontrol means or the attendance of an operaton Atfurther object is toprovide an accumulator-heater:-

changerewhich' is adapted to efiicientlyqassistainv the hot :gas defrosting of the evaporator.

A further object of theinvent-ion, is toprovidean; accumulator-heat exchanger which is adapted tqelficiently assist in the electric defrosting of the evaporator,

A further object of the invention is to provide an accumulator-heat exchanger embodying means to effect heat exchange between super heated refrigerant leaving the compressor and the condensing medium, also between the suction gas leaving the evaporator and the high side liquid.

A further object is the provision of an accumulator-heat exchanger adapted to efficiently assist in the defrosting of a refrigeration system by including means to provide heat for a separate fluid used in the melting of frost from the evaporator and/or the drain pan.

A further object of the invention is to provide an accumulator heat exchanger having a restricted outlet at its bottom for attachment to the compressor suction by means of which oil and a limited or metered quantity of liquid refrigerant may be drawn into the suction line in order to bring the suction gas nearer saturation with the advantages resulting therefrom. These advantages include:

(a) Improving the coefficient of performance of the system;

(b) Increasing the quantity of refrigerant available both for pre-cooling of compressors of the hermetic or semi-hermetic type and for defrosting;

(c) Lowering the compression ratio;

(d) Reducing the work necessary to be done by the compressor.

The foregoing advantages are especially applicable to low temperature systems and systems in which automatic operation is necessary, it being desirable to operate at high efi'iciency under widely variable operating conditions and without the danger of bringing slugs of refrigerant into the compressor.

These and other objects of the invention will become apparent from the following description in conjunction with the accompanying drawings in which:

Fig. 1 is a longitudinal section through a preferred form of an embodiment of the invention;

Fig. 2, a longitudinal section through a modification thereof;

Fig. 3, a schematic diagram of a refrigeration system using my combination accumulator-heat exchanger;

Fig. 4, a schematic diagram illustrating the employment of my device in a system adapted for hot gas defrosting;

Figs. 4a and 4b illustrate the position of the valves of Fig. 4 in the position for normal operation;

Fig. 5, a schematic diagram of my device in a system in which both hot gas and electrically heated coils are provided for defrosting purposes;

Fig. 5a, a diagram of the valve in the position for defrosting;

Fig. 6, a schematic diagram illustrating my device in a system having provision for both hot gas and spray water defrosting;

Figs. 6a and 6b illustrate the position of the valves in defrosting position;

Fig. 7, a schematic diagram of my device used with a refrigeration system having an air cooled compressor in which a separate closed fluid circuit is provided to sub-cool the compressor discharge;

Fig. 8 is a schematic diagram of the separate fluid circuit portion of a system similar to that of Fig. 7 in which the condensers of the main circuit and the secondary circuit are in heat exchange relation;

Fig. 9, a schematic diagram similar to Fig. 8 in which the condensers are cooled by the same fan but are otherwise separate;

Fig. 10, a schematic diagram of a system similar to Fig. 6 except that instead of provision being made for the water line from the heat exchanger to be connected to the evaporator drip pan;

. lator.

Figs. 10a and 10b illustrate the position of the fourway valves of Fig. 10 in defrosting position;

Fig. 11, a section through a combination accumulatorheat exchanger similar to Fig. 1 except that the shell 16 is partially evacuated for insulation purposes instead of having

connections

19 and 20 as in Fig. l; and

Fig. 12, a section on the line 1212 of Fig. 11.

Referring to the drawings, particularly Fig. l, the invention includes an insulated housing 10 having a side Wall 11, preferably of cylindrical configuration, and end

walls

12 and 13. Extending substantially axially of the housing 10 is a central conduit 14 having a shell 15. A second shell 16 extends axially of the housing and about the shell 15. The shell 15 has

connections

17 and 18 at its ends and protrudes substantially outside the

end walls

12 and 13 of the housing 10. The shell 16 likewise has

connections

19 and 20 at its ends but is disposed entirely within the confines of the end walls of the housing 10.

Disposed parallel to the axis of the cylinder and oppositely from each other are a pair of

pipes

21 and 22 which extend into the housing from opposite ends thereof, the pipe 21 entering the end wall 13 and the pipe 22 entering the end wall 12. The ends of the pipes are positioned against the opposite end walls and are closed by

plugs

23 and 24 respectively. The

pipes

21 and 22 are provided with

apertures

25 and 26 on their sides next to the interior wall of the housing.

Referring more particularly to Fig. 3 a diagrammatic circuit is shown illustrating the application of the device to a conventional refrigeration system. The system includes a compressor 30 having a discharge conduit 31 and a suction conduit 32. The conduit 31 is attached to the conduit 14 of the housing 10, the other end of conduit 14 being attached to pipe 33 leading to a watercooled condenser-receiver 34. From condenser-receiver 34 the liquid refrigerant passes through line 35 to expansion valve 36 and to the evaporator 37. From the evaporator the refrigerant is drawn through line 38 and T 39 to pipe 22 within the housing. The refrigerant leaves pipe 22 through apertures 26, passing within the housing through apertures 25 into pipe 21 from whence it flows in the suction line 32 back into the compressor.

A branch line 40 having a one-way valve 41 therein extends from the T 39 to the connection 2% of the shell 16 within the housing. At the other end of the shell 16 a line 42 extends from the connection 19 to the suction line 32. A one-way valve 27 is placed in suction line be tween pipe 21 and the junction with line 42. An oil drain line 44 extends from the connection 45 at the bottom of the housing to the suction line 32. In use liquid refrigerant is also drawn into the line 44 and is metered to the suction line 32.

A Water line 47 having a control valve 46 extends to conduit 48 within the condenser-receiver 34. From the condenser-receiver 34, line 49 extends to the conection 17 of the shell 15 within the housing 10. A connection 18 at the other end of the shell 15 carries the water to a drain pipe 50 In the operation of the device shown in Fig. 3, refrigerant discharges from the compressor 3ft through line 31 and into conduit 14. In conduit 14 it passes through the housing 10 in heat exchange relation with the water passing through the shell 15 coming from condenser-receiver 34. The water temperature is still sufficiently below that of the discharge gas from the compressor to remove heat therefrom in order to effectively increase the capacity of the condenser.

Suction gas from the evaporator 37 passes into and through the housing 10 which thus serves as an accumu- Because of the one-way valve 41 in line 40, the suction gas from the evaporator is prevented from flowing into shell 16. However, since the shell is connected by line 42 to the compressor suction line 32 the pressure in i I! J the shell will apron-mate that of thesuetiohr As meant, shell. 16 :in effect, insulates or reduces heat transfer from :shellls to the interior of the housing. lristead of con- .rrecting the "shell 16 to th'e suction of the compressor the invention also -contemplates merely evacuating the shell themecessary amount, as shown in Fig; 1l,"or the substituti'on 'o'f other insulating media therefor to obtain the desired reduced heat transfer therethrough;

As described above, the system shown in Fig. 3 is an e'xample of an embodiment ofthe invention in an otherwise conventional system:

The invention, however, has particular utility for changing thesystem from normal operation to defrosting, hot compressed gas hein g rhadeavailable for passage through the evaporator coils to elfect or assist in such defrosting "operation:

Referring to Fig; 4.111s system includes the compressor 30,

discharge conduit

51, 52"leadihg to a four-way valve "53, shown in the position for defrosting. Within the valve5 3, conduit 52 is connected by passageway 54 to conduit 55, which is connected to shell 1'6 by line 42 From the shell 16 the refrigerant gas flows t hroughbranch line 40, and valve 41 to T 85 inconduit 56 Conduit "56 is connected by T 57 to

branch lines

58, 59 leadingto evaporators 60, '61, respectively, arranged in parallel.

'In the evaporators 6t) and '61, the gas gives up heat to melt the frost therefrom and in so doing, all or a part of the refrigerant is condensed. From evaporator 60, :refrigerant passes through T 62 to conduit 63 and T 64. Similarly, refrigerant from evaporator 61 passes through T65 and conduit 66 to T 64. From T 64 the combined flow passes through conduit 67 to four-way valve 68, sh'owriin the defrosting position. Four-

way valves

53 and 68 are shown in Figs. 4a and 4b respectively, in their norrnal position for refrigeration operation. In valve 68, the refrigerant from conduit 67 flows through passageway 69 to conduit 70, to the condenser receiver 34; In condenser-receiver 34 the refrigerant is warmed by the water passing through the conduit 48 therein and is then drawn through conduit 71, passageway 72 in valve 53, and conduit '73 into the compressor 30.

During defrosting, hot compressed refrigerant in passing through conduit 14 may be slightly cooled, but not enough :to prevent its subsequent defrosting action. 1 he refrigerant then passes on through the coils 60 and '61, melting the frost therefrom and being partially or entirely condensed. From the coils it flows into the condenser- .receiver 34, whereit is returned to the gaseous phase for subsequent return to the compressor.

In the normal or refrigerating operation of the system, the

valves

53 and 68 are rotated approximately 90 degrees to the positions shown in Figs. 4a and 4b. In such position the refrigerant flows from the compressor, passes through

conduits

51, 14 and 52 to the valve 53 and through the valve and conduit 71 to the condenserrecei-ver 34; From the receiver 34 the liquid refrigerant flows through conduit 70, valve 68 and conduit 75 to T 76. i From T 76the flow separates into conduits 77 and 78

t'oexpansion valves

79 and 80 respectively. From the expansion valves, the refrigerant flows through

evaporators

60 and 61 to conduit 56, to pipe 22 shown in the lower part of the housing 10. From pipe 22, the gaseous refrigerant flows into pipe 21 to conduit 55 and valve 53 to conduit 73, the suction line of the compressor 30, shell 16 being under suction pressure to insulate it as described above.

Fig; 5 illustrates an application of the present inventio'min which electric heating coils 90 are employed to supplement the hot gas defrosting of the Fig. 4 embodimenu The valve '53 is shown in the system in the position for normal refrigeration operation. In Fig. So it is stews one position for defrosting. Inasmuch as only l u central conduit 14 and con'duit i in Fig. 5; a valvesiinilar to whats in Fig; 4 is not required. I V

In order that during defrosting refrigerant may "circulatethro'dgh evaporator 37 back to condenser-receiver '34, a bypass 91is connectedaround expansion valve36 and preferably has a pressure operated one-way valve 92 thereir'n'w'hichis set to open at a predetermined minimum pressure. p v

In Fig. 6; a system is shownwhich is" adapted to defrost through both the use of hot gas and also by water which has been warmed through heat exchangewiththe hot gas. Thesy'stem includes elements similar to those of Figs. 3, 4, and 5 and, in addition, means for conveying water from the shellIG to the coils of the evaporator. Conduit 50 from the discharge end of shell 15 extends to a fo'u'rway valve 101'. In Fig. 6 the valvesare shown in position for normal" re'ffigeration operation arid in Figs. 6a, 6b for defrosting. Accordingly, with the valves in the position shown tern. 6, the water flows through its passa'gevvay 102 to pipe 103 and out through the drain 104.

When valve 10 1 is in the position for defrosting, the water flows from conduit 102 through the valve to cond 1 1 03 and then to a spray or other distribution means 106. Fromthe spray 106, the water passes downwardly over fheevaporator 37 to the drain pan 108 and is discharged-through the drain 104.

"In thedetrosting operation of the system, the refrigera nt flows in a circuit similar to that of Figs. 3, 4 and 5. The water entering through conduit 47 is cooled in passing through conduit 48 within the receiver-condenser and then flowsin the shell 16 around the central conduit 14 and in counter-flow to the hot gaseous refrigerant passing theret'hrough. In so doing, the water picks up more heat than waslost in conduit 48, including that from friction losses in the compressor, so that it may efliciently remove frost from the outside of the evaporator coils 37. At the same time, the hot gaseous refrigerant flows into the coils 37 supplying heat thereto, in order to assist in the melting of the accumulated frost.

In accordance with one method of operating the system the condensed refrigerant from evaporator 37 flows around the expansion valve through bypass 91 and valve 92 back into the line going to the receiver. In accordance with another method. of operating the device, however, the bypass around the expansion valve is set to remainclosed during normal defrosting so that flow of refrigerant back to the receiver from the coils is prevented. Under this latter method the compressor keeps pumping against the pressure in the line but the refrigerant circuit is closed. Defrosting, however; is carried out by the water coming in through the pipe 47 supplemented by the heat obtained from the refrigerant gas within the evaporator whose temperature is raised somewhat as a result of being under pressure. The oper ation of the device in accordance with this second method is somewhat simpler than that first described, both however, permitting the compressor to run continuously. Thus there is provided a single coil gas defrosting system in which the compressor may operate continuously.

Whether it is preferable to have the system defrost by permitting flow of refrigerant through bypass 91 depends on several factors. Generally, if the evaporator is so constructed as to require a relatively long time for defrosting, the by-pass will have to be open to permit the refrigerant to circulate and provide additional heat. If

a relatively short defrost period is adequate, as for example, in an evaporator with few coils,

tor to defrost without full circulation.

Fig. 10 is similar to Fig. 6 except that instead of having.

a hook-up for spraying water over the coils as in Fig. 6, line 109 extends from the four-way valve 101 to the; drip enough heat maybe obtainable from the gas under pressure in the evapora-- and 104. During defrosting, the four-way valves may be positioned as shown in Figs. 10a and 10b, the valve 101 in such position diverting the water into the drip pan. The water will thus assist in melting fragments of ice dropping from the coils and thus prevent clogging of the drain.

Fig. 7 illustrates the application of the device of my invention to a system similar to that of Fig. 3, except that an air-cooled condenser is employed instead of using water for removing some of the superheat from the refrigerant in conduit 14, a separate closed fluid system is employed. In Fig. 7, compressor 30 discharges refrigerant through conduit 31 to condenser 110 and then through conduit 51 to conduit 14 within the housing, the con denser being in the line ahead of conduit 14 for greater efficiency. From conduit 14 the refrigerant passes to receiver 111 and conduit 35, to the evaporator 37. From the evaporator, the return flow to the compressor 30 is the same as described above in connection with Fig. 3.

In order to supply cooling fluid to shell about conduit 14, a separate system is provided having a condenser 112 and receiver 113. From receiver 113, the fluid passes through conduit 114 to restricter 115. From restricter 115, the flow is through conduit 116 to connection 18 of shell 15. After flowing through shell 15 and being evaporated by heat from the refrigerant passing through conduit 14, the fluid from the shell discharges through connection 17 to conduit 117 and is then returned to the condenser 112.

Instead of having the condenser 110 of the refrigeration system separate from the condenser 112 of the separate fluid cooling system, the invention contemplates the combining of features as shown in Figs. 8 and 9. In Fig. 8 the conduit 117 from the shell 15 enters one end of a shell 1211 of a tube condenser 121. After passing the length of the

shells

120, 122 and 123 of the condenser, the fluid is discharged to the receiver 113 through conduit 117. The refrigerant from the compressor, after passing through the central conduit 14, passes through the tube 124 of the shell and tube condenser 121 to the receiver 111, the flow through the tube 124 being counter to that of the fluid through the shells 12th, 122 and 123.

Fig. 9 discloses a system similar to that of Fig. 8, except that instead of employing a shell and tube condenser for heat exchange between the fluid in the shells and the refrigerant in the tube, separate condenser coils are use The device of Figure 2 is a modification of that of Fig. l and includes a housing 210 having a side wall 211 and end

Walls

212 and 213. Conduit 214 extends axially and 5' centrally of the housing and has shell 215 which does not extend beyond the housing as in Fig. l but is instead entirely therewithin.

Connections

217 and 218 are attached to either end of the shell 215. Shell 216 surrounds shell 215 and is similar to shell 16 of Fig. 1 having

connections

219 and 220.

Pipes

221 and 222 are likewise disposed oppositely to each other as with

pipes

21 and 22 in Fig. 1. Instead of having circular apertures as with the pipes of Fig. 1, saw tooth apertures 225 and 226 are provided. It is of course understood that apertures of various shapes may be employed.

Fig. 2 differs from Fig. l chiefly in that Fig. 2 illustrates a combined accumulator-heat exchanger disposed within a Water cooled condenser. Accordingly, spaced

walls

230 and 231 which conform generally to the shape of the housing 219 enclose within the housing the conduits and pipes described above.

Connections

232 and 233 are connected to the outer wall 231 in order that the space between the

walls

231 and 231 may be evacuated to the degree necessary to afford the desired amount of insulation. It is contemplated, however, that other means of insulating the space may be provided.

Wrapped around the wall 231 is coil 235 adapted to carry cooling water which enters the end 236 of the tube and leaves by the end 23", from which it is passed by a return bend (not shown) to a connection 217 for flow through shell 215 about the conduit 214. Space 239 between the wall 231 and the

Walls

211, 212, and 213 of the housing 210 is adapted to have the refrigerant pass through it, after precooling in conduit 214, in order to be condensed by heat exchange with the liquid flowing through the pipes 235. Accordingly an inlet connection 241 is provided at the top of the condenser and a discharge connection 242 at the lower side thereof.

Fig. 11 discloses an accumulator heat exchanger unit similar to Fig. 1 except that the

connections

19 and 20 of Fig. 1 are omitted and the shell 16' of Fig. 11 is evacuated to produce the desired degree of insulation. Instead of evacuating shell 16', other insulating means may be provided.

Figs. 11 and 12 also illustrate the use of fins 245 on the conduit 14 and shell 15, the provision thereof obviously being Within the scope of the invention.

While the device of my invention is shown in several particular applications, it is understood that its use is not restricted to those but that it may be used in others as well. It is further understood that the invention is not limited to the particular construction of the illustrated embodiments but that various modifications and substitutions are within the scope of the invention.

What is claimed is:

1. For use with a refrigeration system having a cornpressor, condenser, and evaporator, an accumulator heat exchanger comprising a central conduit for the passage of compressed refrigerant, said central conduit being provided for passing refrigerant from the compressor to the condenser, said condenser being fluid cooled, at first shell about said central conduit for the passage of said cooling fluid leaving the condenser, inlet and outlet connections in said first shell for said cooling fluid, insulating means about said first shell, a housing around said central conduit, said first shell, and said insulating means, said housing having inlet and outlet ports communicating with each other within said housing, said inlet port being provided for connection to the discharge of the evaporator for receiving refrigerant therefrom, said housing having a storage space for liquid refrigerant, said outlet port being provided for connection to the compressor and being spaced from said storage space to prevent flow of a liquid therethrough, the insulating means limiting exchange of heat between the refrigerant and fluid in the conduit and first shell, respectively, and the refrigerant returning from the evaporator.

2. The structure of claim 1, said insulating means comprising a second shell about said first shell, said second shell having a connecting means adjacent to each of its ends, one of said connecting means being provided for connection to the compressor suction, the other of said connecting means being provided for connection to the evaporator discharge.

3. In a refrigeration system, a first cooling means for compressed refrigerant in which superheat is removed therefrom, a fluid cooled condenser in which the cooled compressed refrigerant is condensed, means for passing compressed refrigerant from said first cooling means to said condenser, means for passing cooling fluid from the condenser to said first cooling means for condensing and for removing superheat from the compressed refrigerant, respectively, a housing around the first cooling means, an evaporator, said housing having a storage space for liquid refrigerant and an outlet to the compressor suction, the outlet being spaced from the storage space to prevent flow of liquid therethrough, means connecting the housing to the evaporator whereby refrigerant returning from the evaporator passes through the housing on its way to the compressor suction, and means limiting heat transfer within the housing between said returning refrigerant and said compressed refrigerant and cooling fluid.

4. The structure of claim 3, a second outlet to the compressor suction, said second outlet being restricted and being positioned adjacent to the lower portion of the housing whereby liquid collecting in the lower portion of the housing may be metered into the compressor suction.

5. For use with a refrigeration system having a compressor, condenser, and evaporator, an accumulator heat exchanger comprising a central conduit, a first shell about said central conduit, inlet and outlet connections in said first shell, insulating means about said first shell, a housing around said central conduit, said first shell, and said insulating means, said housing having inlet and outlet ports communicating with each other within said housing, said inlet port being provided for connection to the discharge of the evaporator for receiving refrigerant therefrom, said housing having a storage space for liquid refrigerant, said outlet port being provided for connection ot the compressor and being spaced from said storage space to prevent flow of liquid therethrough, the insulating means limiting exchange of heat between the 10 refrigerant and fluid in the conduit and first shell, respectively, and the refrigerant returning from the evaporator.

References Cited in the file of this patent UNITED STATES PATENTS