US2462329A - Evaporator having refrigerant recirculation means - Google Patents

Description

Feb. 22, 1949.

'H. G. MOJONNIER I EVAPORATOR HAVING REFRIGERANT RECIRGULA'I'ION MEANS 7 Filed Jan. 12, 1945 3 Sheets-Sheet 2 IN V EN TOR. fid/rry lfoj'arziz'efl M aw/w e 9- H. G. MOJONNIER 2,462,329

EVAPORATOR HAVING REFRIGERANT REGIRCULATION MEANS Filed Jan. 12, 1945 3 Sheets-Sheet 3 Patented Feb. 2, 19 49 UNITED STATES PATENT OFFICE EVAPORATOR HAVING REFRIGERANT RECIRCULATION MEANS Harry G. Mojonnier, Oak Park, Ill. Application January 12, 1945, Serial No. 572,527

Claims.

This invention relates to refrigerating apparatus, and particularly to cooler or evaporator structures and cooling methods used in conlunctioh therewith.

It is an object of the invention to provide improved cooling apparatus, particularly adapted for use in refrigeration systems intended for the cooling of fluids, such as liquids and gases, and wherein the fluids to be cooled may be circulated throug thecooling apparatus during the cooling processes.

More specifically stated, it is an object of the invention to provide means of the type stated, which are more efficient in operation, providing a maximum cooling of the medium to be cooled with the use of a minimum of refrigerant, while further providing accurate temperature control and uniformity of operation.

A further object of the invention is to provide an evaporator or cooler unit, of the refrigerant flooded type, which is of compact and improved construction, providing a maximum area and etficien'cy of thermal contact between the refrigerant and the medium to be cooled, in respect to the size of the unit, and improved provisions for sanitation.

A still further object of the invention is to providean improved cooler structure wherein the refrigerant and the'medium to be cooled, while in thermal or. heat transfer contact, are subjected to counter-flow in respect to each other while the refrlgerantis continuously maintained in a condition facilitating a maximum absorption of heat from the cooled medium.

Another obiect of the invention is to provide a cooler or evaporator structure of the flooded type,

wherein return of liquid refrigerant from the evaporator to the compressor is precluded or minimized, as may be required.

Various other objects, advantages and features of the invention will be apparent from the following specification, when taken in connection with the accompanying drawings, wherein certain preferred embodiments are set forth for purposes of illustration.

In the drawings, wherein like reference numerals refer to like parts throughout:

Fig. 1 is a general layout, diagrammatic in form, are" refrigerating system incorporating a cooler or evaporator unit,'constructed in accordance with and embodying the principles of the invention; i

Fig. 2 is view; on an enlarged scale, partly in side elevation and partly in section, of the evaporefrigerating apparatus,

or evaporator of the invention as arranged to effeet the cooling and gas charging of a liquid; a Fig. 6 is a plan view of the apparatus of Fig. 5; Fig. 7 is a detail view generally similar to Fig. 2,

15 but showing the evaporator as embodied in the structures of Figs. 5 and 6 and taken as indicated by the line 1-1 of Fig. 6; and

Fig. 8 is a view generally similar to Fig. 4, but

showing a cooling unit in the modified form of evaporator of Figs. 5, 6 and '1.

Referring first to the embodiment illustrated in Figs. 1, 2, 3 and 4, in Fig. 1 there is shown, diagrammatically, a refrigerating apparatus incorporating the evaporator or cooling unit of the invention. As shown, the apparatus comprises a compressor or ice machine In driven from a suitable source of power, such as an electric motor ii, The compressed gaseous refrigerant, which may for example be ammonia or Freon, is trans-.

mitted by means of a pipe or conduit I! to a condenser, diagrammatically indicated at l3. In the condenser the refrigerant is condensed into liquid form, and transmitted by means of a conduit M to an injector structure l5, later to be described, by means of which it is introduced into the cooler or evaporator, generally indicated by the numeral IS.

The fluid or liquid to be cooled is introduced into the evaporator by means of a supply pipe l8,

40 under control of an inlet valve l9. Within the evaporator the refrigerant medium and the fluid medium to be cooled are subjected to thermal contact, in a manner more specifically to be described, and a heat exchange takes place, as will be understood. The cooled fluid or liquid is suitably exhausted from the evaporator through an exhaust pipe 20. The refrigerant, transformed into a gaseous state within the evaporator, is exhausted therefrom through an exhaust line 2| under control of a back pressure regulating valve 22, being returned to the compressor for recirculation through a return line 23.

The details and construction of the cooler or evaporator unit it are illustrated in Figs. 2, 3

and 4. ;The unit comprises an outer cylindrical 3 metal shell or cover plate 25, and an inner cylindrical metal shell 25, between which is interposeda wall of insulating material 21 such, for example, as cork or the like. The shell 26 is secured at its upper end, as by welding or the like, to a tube sheet 28, and at its lower end to a tube sheet 28, whereby to form a cylindrical tank-like structure into which the refrigerant is adapted to be introduced, as will be described. The outer cover shell embraces these tube sheets and extends therebetween. I

Disposed somewhat above the lower tube sheet 29, and in spaced relation thereto, is a separating baille wall and tube sheet 20. This baffle wall extends completely across the tank interior, being secured to the inner shell 25, as by welding or the like, whereby to provide within the tank, an upper refrigerant chamber 3| and a lower refrigerant chamber 22, the chambers being separated by said baille wall 20.

A series of pipes or tubes 25 are arranged within the structure, being anchored, respectively, at their upper and lower ends within the tube sheets 28 and 29. The baille wall tube sheet 30 carries a series of tubes 38, slightly larger than the tubes 25, and arranged in concentric relation thereto. The tubes 26, in the particular embodiment shown, are unsupported at their upper ends, opening directly into the upper refrigerant chamber 2|. If desired, the upper tube ends could be supported from the tubes 35, or from a tube sheet or spider, similar to the tube sheet 20.

The detailed manner in which the tubes are supported by the tube sheets is best illustrated in Fig. 4. As shown, the tubes may be expanded, as indicated at I] and 28 into annular recesses provided, respectively, in-the tube sheets 28 and 29 whereby to hold the tubes firmly in position. It is to be understood, however, that various other suitable securing means may be employed. The tubes 36 may, for example, be welded to the baffle wall tube sheet 20, or other suitable securing means may be provided. It will be seen that due to .the difl'erence in size of the tubes, and the concentric disposition thereof, annular spaces or passages 40 are formed between the tubes, these passages communicating at their upper ends with the upper refrigerant chamber 3!, and at their lower ends with the lower refrigerant chamber 32.

A head member 42 of dome-like shape is provided at the upper end of the structure, this head member forming with the tube sheet 28 an upper head chamber 43 into which the fluid medium to be cooled is introduced by the inlet pipe I8, which may, for example, be formed as an integral part of the dome-like head. A ring member 44 may be welded to the lower portion of the dome 42, and secured by a series of bolts 45 to the tube sheet 28, a gasket 46 being interposed between the parts to provide a fluid-tight connection. The ring 44 and bolts 45 thus form suitable means for securing the head 42 in position,

but obviously other suitable securing means may be employed.

At the lower end of the structure there is provided a dome-like head 48 secured to the lower tube sheet 29 by a ring member 49 and a series of bolts 52, in a manner similar to that described in reference to the upper head structure. The lower dome head 48, with the tube sheet 29, forms a lower chamber or reservoir 5| for the flllid medium to be cooled, and communicating with the upper head chamber 43 through the tubes 35.

4 A portion of the outlet conduit 28 for the cooled fluid medium may be formed as an integral part of the lower head dome 48.

As best shown in Fig. 4, each of the tubes 25 is provided at its upper end with a cap member 53, this cap member being provided with a series of openings 54 of predetermined size for metering and controlling the rate of fluid flow through the tubes 25 and between the upper and lower chambers 42 and 5i, as will be later described.

For circulating the refrigerant between the upper and lower refrigerant chamber 2| and 22, and for injecting the liquid refrigerant from the condenser into the evaporator unit, the injector structure i5 is provided. Specifically the injector comprises a housing 56, bolted to the evaporator shell by means of a series of bolts 51. The housing forms a chamber 58 communicating with the upper refrigerant chamber 3|, and within this chamber is an injector throat 58 arranged to transmit the refrigerant from the chamber 58 into the lower refrigerant chamber 32 of the evaporator. An injector nozzle 58 communicating with the refrigerant inlet pipe I 4 provides the power means for circulating the liquid refrigerant through the injector throat 52, as well as for continuously injecting replacement refrigerant liquid into the unit. The injector nozzle 60 will be of predetermined selected size, in accordance with the cooling capacity and requirements of the system. In operation, several times as much liquid refrigerant circulates through the injector throat 59, as is introduced through the injector nozzle 68.

The vaporized refrigerant, vaporized within the evaporator by reason of the heat transfer processes, is ejected from the evaporator through the pipe 2| from the upper part of the upper refrigerant chamber 3 I, under control of the back pressure regulating valve 22. A baffle 62 is provided, in association with the pipe 2!, for precluding inadvertent return of liquid refrigerant from the evaporator.

A pair of sight glasses 4! and 84 are provided in association, respectively, with the upper and lower refrigerant chambers if and 32, for observing conditions therein, and a thermometer or heat indicator 55 is associated with the liquid body in the upper refrigerant chamber, for determining the thermal conditions in the system.

In operation, the fluid medium to be cooled is introduced into the upper head chamber 42 from the inlet supply pipe I I. The upper tube sheet 28 and the cap members 52 with their oriiices 54 form a distributor structure for causing the fluid flow downwardly through the pipes 35 to take place uniformly .in respect to all of the tubes, and at a predetermined rate. Preferably this rate is so determined that the fluid or liquid to be cooled which may, for example, be water is transmitted in the form of a thin fllm downwardly along the walls of the tubes into the lower head reservoir 5i, from which the cooled water is withdrawn through the outlet pipe 28.

The refrigerant, in liquid form, is transmitted to the evaporator by means of the refrigerant inlet pipe I4, and is introduced into the evaporator at a predetermined rate in accordance with the cooling capacity of the system, by the predetermined size injector nozzle 80. The action of the injector nozzle also produces a circulation of liquid refrigerant, in a volume greater than that introduced through the nozzle, through the injector throat 59 and between the upper and lower refrigerant chamber 3i and 22. In passing from the chamber 32 to the chamber 3|, the liquid refrigerant passes upwardly through the tubes 36, and through the annular passages 40 in embracing relation to the water tubes 35, a heat exchange between the refrigerant and the water or other liquid or fluid to be cooled taking place. At the upper end of the tubes 36 the liquid refrigerant overflows into the chamber 3|. In normal operation the liquid level of refrigerant within the chamber 3| may be maintained, for example, approximately at the line A-A, as indicated in Figs. 1 and 2, the liquid refrigerant being initially charged into the evaporator, and maintained by the injection of replacement refrigerant through the nozzle 60, at substantially this level. In the upper spaces 3|" of the chamber 3| the gaseous refrigerant, vaporized by the heat transfer processes, is separated from the liquid, and returned to the compressor through the outlet pipe 2| and back pressure regulating valve 22. As earlier indicated, the baffle plate 62 prevents the liquid refrigerant overflowing from the tubes 36 being inadvertently transmitted to the outlet pipe 2 l.

Particular attention is directed to the fact that whereas a body of liquid refrigerant is maintained within the unit only to the level A-'A, or thereabouts, the concentric tube arrangement is such that substantially the entire length of the water pipes 35 is immersed in and subjected to the action of a bath of liquid refrigerant. This arrangement provides a maximum cooling capacity, in respect to the size of the unit, with a minimum of refrigerant. The use of smaller quantities of refrigerant reduces costs, and minimizes oil accumulation within the evaporator which may separate from the refrigerant in the operation of the system. The refrigerant in contact with the heat transfer surfaces of the water tubes 35 is in continuous circulation turbulence, and movement, facilitating the heat transfer processes. A compact flooded type cooling unit is provided of a maximum efficiency, and wherein temperatures may be uniformly controlled.

The distributor caps 53 provide for a down flow film of the water to be cooled, along the walls of the tubes 35, whereas the injector provides a continuous counter-flow film of liquid refrigerant upwardly along the outer surfaces of the tubes 35, facilitating a maximum heat transfer. Counter-flow of the water and refrigerant is preferred, and is readily effected in the structure provided. It is obvious, however, that the medium to be cooled may be propelled in any desired direction through the structure. The multiplicity of tubes provides a minimum pressure drop for the refrigerant within the system. The relatively low liquid level within the chamber 3| insures an adequate gas separation space 3|, precluding the transmission of liquid refrigerant through the outlet pipe 2|, or surging of liquid therethrough, under various operating conditions as when the system is started or the like. The removable heads 42 and 48 permit ready access to the internal parts of the tank structure contacted by the medium to be cooled, thus facilitating cleaning.

In Figs. 5, 6, 7 and 8 an embodiment is illustrated wherein the cooler or evaporator is arranged as a part of a complete refrigerating apparatus, and wherein during the cooling of the liquid medium to be cooled, a simultaneous gas charging or carbonating of the liquid takes place.

Referring to Figs. 5 and 6, the apparatus shown comprises a compressor Illa driven by an electric motor Ila through drive connections 18, and adapted to propel gaseous refrigerant by means of a pipe or conduit I2a, under control of a hand valve II, to a water cooled condenser l3a. The condensed liquid refrigerant is transmitted by means of a conduit Ma under control of a hand valve 12, and a solenoid valve 13 automatically opened when the motor Ila is energized, to the injector |5a by means of which the refrigerant is injected into the evaporator IBa as in the structure previously described. The vaporized refrigerant is returned from the cooling unit by means of a pipe 2|, a under control of a back pressure control valve 22a, and then returning by means of a return line 23a and a hand control valve 14, back to the suction side of the compressor.

The fluid medium to be cooled, which may in this instance be water mixed with flavoring syrup, is supplied from a conduit 15 to a pump 16 driven by an electric motor ll. From the pump the liquid is transmitted by means of a pipe |8a and check valve 18 into the upper dome head 42a of the cooling unit. Within the evaporator, the water is cooled in the manner previously described, passing from the lower head dome 48a of theevaporator by means of an outlet pipe 2lla to a storage tank 19, from which it may be drawn as desired by means of an out- 4 let pipe under control of a-valve 8|. In the particular embodiment shown the cooled water discharge pipe has associated therewith a safety blow-01f valve 82, for a purpose presently to be described, there also being a sight glass 83 asociated with the discharge water pipe to observe the flow of liquid therethrough.

An electric control unit or switch 85, controlled by the liquid level within the reservoir tank 19, and arranged to control the operation of the pump motor 11, may be provided so as to start the pump motor whenever the liquid level within the tank 19 drops below a predetermined amount.

The reservoir tank 19 may be drained, as required, by means of a drain valve 81. A drain valve 88 is associated with the lower reservoir chamber 32a within the evaporator unit, for draining accumulated oil separating from the refrigerant within the evaporator unit. Apressure equalizing line 89 connects the top of the tank 19 with the lower head chamber of the evaporator, to facilitate proper flow through the drain line 20a.

In the present embodiment, means is provided for carbonating the syrup water, with air or carbon dioxide gas, simultaneously with the cooling thereof. To this end a supply line 88 is provided leading from a suitable source of carbon dioxide gas pressure. A pressure regulator 9| reduces the gas pressure to a predetermined value, after which the gas passes through a shut off control valve 92 through a line 93 into the lower head chamber of the evaporator unit, as best shown in Figs. 5 and '7. Within the evaporator it will be seen that the gas may pass upwardly through the tubes 35a, Figs. '7 and 8, into t e upper head chamber 43a. the cap members 53a in this instance being provided with upstanding pipe portions 95 communicating with the upper part of the upper head chamber so that the gas pressure, or flow of gas, may not interfere with the down flow of the syrup water through the cap orifices 54a.

The operation of the structure of Figs. 5, 6, 7

and 8 is believed to be clear from what has heretofore been stated, sumce to say that in this instance, as the syrup and water mixture is cooled by down flow through the tubes a, embraced by the liquid refrigerant, the water is simultaneously subjected to a carbonating process by the carbon dioxide gas pressure within the tubes Ila and within the upper and lower head cham bers a and ila, so that as the syrup water is discharged through the drain line a into the storage tank 19, it will comprise a carbonated beverage liquid. The safety valve 82 provides a safety pressure relief, in the event of abnormal pressures within the evaporator unit. a

As is obvious, the structure may be employed to carbonate syrup water, plain water, or other medium to be treated.

Referring further to Fig. 5, preferably the temperature indicator 65a includes a thermostatically controlled switch in the control circuit for the pump motor 11, so as to stop the pump if the evaporator temperature drops below or goes above predetermined limits. Proper cooling is thus insured. When temperatures are too low, ice may form on the tubes 35a, forming an insulating wall resulting in improper cooling.

As best shown in Fig. 5, the upper head chamber may be provided with an indicator or pressure gauge 91, and with a purge valve 98. which may be manually opened from time to time, as may be required. As will be understood, the other manually operable valves in the system, such as the valves 1|, 11, 14, ill and 92 are normally open, with the exception of drain valves 81 and 8| which are normally closed.

It is obvious that various changes may be made in the specific embodiments set forth for purposes of illustration without departing from the spirit of the invention. For example, the water or other medium to be cooled could be circulated through the unit in a plurality of passes or, the structure could be adapted for horizontal as distinguished from vertical positioning. Accordingly the invention is not to be limited to the specific embodiments shown and described, but only as indicated in the following claims.

The invention is hereby claimed as follows:

1. An evaporator for use with refrigerating apparatus comprising a tank structure, a pair of elongated tube members within the tank structure, said tube members being of different size, means for supporting the smaller tube within the larger tube, means forming a gas and liquid refrigerant separator chamber within the tank structure, means interconnected with said chamber for transmitting a refrigerant medium through one of said tubes, said refrigerant transmitting means including means for individually withdrawing gas and liquid phases of the refrigerant from said separator chamber, and means for transmitting a medium to be cooled through the other tube, whereby the wall surfaces of the smaller tube constitute a heat transfer surface engaged by the refrigerant medium and the medium to be cooled to eil'ect an exchange of heat therebetween..

2. An evaporator for use with refrigerating apparatus comprising a tank structure, a mind elongated tube members within the tank structure, said tube members being of different size, means for supporting the smaller tube within the larger tube, means forming a gas and liquid refrigerant separator chamber within the tank structure, means interconnected with said chamber for transmitting a refrigerant medium through one of said tubes, said refrigerant transmitting means including means for individually withdrawing Ill and liquid phases of the refrigerant from said separator chamber, means for transmitting a medium to be cooled through the other tube, whereby the-wall surfaces of the smaller tube constitute a heat transfer surface engaged by the refrigerant medium and the medium to be cooled to effect an exchange of heat therebetween. and flow restricting means for restricting the flow of the medium through the smaller tube so that said medium forms a film on the inner surface of said tube.

3. An evaporator ,for use with refrigerating apparatus comprising a tank structure, a pair of elongated tube members within the tank structure, said tube members being of different diameter, means for supporting the smaller tube within the larger tube, means forming a gas and liquid refrigerant separator chamber within the tank structure, means for individually withdrawing gas and liquid phases of a refrigerant medium from said separator chamber and for circulating theliquid phase of the refrigerant medium from said chamber through one of the tubes, and means for transmitting a. medium to be cooled through the other tube, whereby the wall surfaces of the smaller tube constitute a heat transfer surface engaged by the recirculating refrigerant medium and the medium to be cooled to effect an exchange of heat therebetween.

4. An evaporator for use with refrigerating apparatus comprising a tank structure, a pair of elongated tube members within the tank structure, said tube members being of different diameter, means for supporting the smaller tube within the larger tube, means forming a gas and liquid refrigerant separator chamber within the tank structure, means interconnected with said chamber for individually withdrawing gas and liquid phases of a refrigerant medium from said separator chamber and for transmitting the liquid phase of the refrigerant medium through one of said tubes in one direction, and means for transmitting a medium to be cooled through the other tube in the opposite direction, whereby the wall surfaces of the smaller tube constitute a heat transfer surface engaged by the oppositely flowing refrigerant medium and medium to be cooled to effect an exchange of heat therebetween.

5. An evaporator for use with refrigerating apparatus comprising a tank structure, a first set of elongated passages extending through the tank structure, a second set of elongated passages extending through the tank structure, the individual passages of said sets being in thermal contact, means forming a gas and liquid refrigerant separator chamber within the tank structure, means interconnected with said chamber for individually withdrawing gas and liquid phases of a refrigerant medium from said separator chamber and for transmitting the liquid phase of the refrigerant medium through one of said sets of passages, and means for transmitting a medium to be cooled through the other set of passages, whereby to effect an exchange of heat between the refrigerant medium and the medium to be cooled as said mediums are transmitted through said sets of passages in thermal contact.

6. An evaporator for use with refrigerating apparatus comprising a tank structure, a first set of elongated passages extending through the tank structure, a second set of elongated passages extending through the tank structure. the individual passages of said sets being in thermal contact, means forming a gas and liquid refrigerant separator chamber within the tank structure, means for individually withdrawing gas and liquid phases of a refrigerant medium from said separatorgchamber and for recirculating the liquid phase of the refrigerant medium from said chamber through one of said sets of passages, and means for transmitting a medium to be cooled through the other set of passages, whereby to effect an exchange of heat between the recirculating refrigerant medium and the medium to be cooled as they are transmitted through said sets of passages in thermal contact.

'7. An evaporator for use with refrigerating apparatus comprising a tank structure, a first set of elongated passages extending through the tank structure, a second set of elongated passages extending through the tank structure, the individual passages of said sets being in thermal contact, means forming a gas and liquid refrigerant separator chamber Within the tank structure, means interconnected with said chamber for individually withdrawing gas and liquid phases of a refrigerant medium from said separator chamber and for transmitting the liquid phase of the refrigerant medium through one of said sets of passages in one direction, and means for transmitting a medium to be cooled through the other set of passages in the opposite direction, whereby to effect an exchange of heat between the refrigerant medium and the medium to be cooled.

8. An evaporator for use with refrigerating apparatus comprising a tank structure, a reservoir forming a gas liquid separator for refrigerant formed within said tank structure, means for individually withdrawing the gas and liquid phases of the refrigerant from said reservoir to thereby maintain a predetermined liquid level of refrigerant within said reservoir, a first set of elongated passages extending through the tank structure, said passages being in communication with said reservoir but being of greater longitudinal extent within the tank structure than the liquid body in said reservoir, a second set of elongated passages extending through the tank structure, the individual passages of said sets being in thermal contact, said withdrawing means including means for circulating refrigerant between said reservoir and said first set of elongated passages, and means for transmitting a medium to be cooled through said second set of passages, whereby to effect an exchange of heat between the refrigerant medium and the medium to be cooled.

9. An evaporator as defined in claim 8, wherein said refrigerant withdrawing means includes an injector structure.

10. An evaporator for use with refrigerating apparatus comprising a tank structure, a reservoir forming a gas liquid separator for refrigerant formed within said tank structure, means for individually withdrawing the gas and liquid phases of the refrigerant from said reservoir to thereby maintain a predetermined liquid level of refrigerant Within said reservoir, a first set of elongated tubes extending through the tank structure, said tubes being in communication with said reservoir but being of greater length within the tank structure than the liquid body in said reservoir, a second set of elongated tubes extending through the tank structure, the tubes of one of said sets being smaller than the tubes of the other set and being supported therewithin, said withdrawing means including means for circulating refrigerant between said reservoir and said first set of tubes, and means for transmitting a medium to be cooled through said second set of tubes, whereby to effect an exchange of heat between the refrigerant medium and the medium to be cooled.

11. An evaporator as defined in claim 10, wherein said refrigerant withdrawing means comprises an injector structure for circulating the liquid phase of the refrigerant.

12. An evaporator for use with refrigerating apparatus comprising a tank structure, a head chamber formed at one end of said tank structure, a head chamber formed at the other end of said tank structure, a set of tubes extending between said head chambers and communicating therewith, a fluid reservoir disposed within said tank structure extending longitudinally thereof between said head chambers, individual outlets leading from said reservoir adjacent its opposite longitudinal ends, a set of tubes communicating with said reservoir, the tubes of one of said sets being smaller than the tubes of the other set and being respectively disposed therewithin, and means for transmitting a re-' frigerant medium through one of said sets of tubes and for transmitting a medium to be cooled through the other sets of tubes, whereby to effect an exchange of heat therebetween, said refrigerant transmitting means including means for individually withdrawing gas and liquid phases of the refrigerant from the individual outlets of said reservoir. a

13. An evaporator for use with refrigerating apparatus comprising a tank structure, a head chamber formed at one end of said tank structure, a head chamber formed at the other end of said tank structure, a set of vertically disposed tubes extending between said head chambers and communicating therewith, a pair of fluid reservoirs disposed within said tank structure between said head chambers, one of said reservoirs being elongated longitudinally of the tank and forming a gas and liquid separator for refrigerant, a set of tubes communicating with said reservoirs, said first named set of tubes being smaller than the last named set of tubes and being respectively disposed therewithin, and means for transmitting a refrigerant medium through the larger set of tubes and for transmitting the medium to be cooled through the smaller set of tubes, whereby to effect an exchange of heat therebetween, said refrigerant transmitting means including means for individually withdrawing gas and liquid phases of the refrigerant from said elongated reservoir.

14, An evaporator for use with refrigerating apparatus comprising a tank structure, a head chamber formed at one end of said tank structure, a head chamber formed at the other end of said tank structure, a set of vertically disposed tubes extending between said head chambers and communicating therewith, a pair of superposed fluid reservoirs disposed within said tank structure between said head chambers, one of said reservoirs being elongated longitudinally of the tank and having individual outlets at the opposite longitudinal ends thereof, said reservoir forming a separator for gas and liquid refrigerant, a set of tubes communicating at their ends respectively with said reservoirs, the tubes of said last named set being larger than the tubes of the first named set and being respectively in embracing relation therewith, means for withdrawing refrigerant gas from one of said outlets and for transmitting refrigerant liquid 11 between the reservoirs through said other outlet whereby to maintain liquid refrigerant within the lower of said reservoirs and to a predetermined level within the upper of said reservoirs and for circulating the refrigerant between said last named outlet.

HARRY G. MOJONNIER 12 ammcas 01mm The following references are of record in the file of this patent:

UNITED STATIB PATENTS Number Name -Da tc 2,058,907 Phiiipp Oct. 27, 1936 2,063,646 Whitesel Doc. 8. 1936 10 2,233,059 Miller Feb. 25, 1941 2,387,899 Gruner Oct. 30, 1945

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