US2933904A

US2933904A - Refrigeration system

Info

Publication number: US2933904A
Application number: US646327A
Authority: US
Inventors: Donald C Wellman
Original assignee: Carrier Corp
Current assignee: Carrier Corp
Priority date: 1957-03-15
Filing date: 1957-03-15
Publication date: 1960-04-26
Anticipated expiration: 1977-04-26

Description

441311126, 1960 D. c. WELLMAN 2,933,904

REFRIGERATION SYSTEM Filed March 15, 1957 FIG. 3 52 INVHVTOR. DONALD c. WELLMAN.

ATTORNEY.

United States Patent 6 REFRIGERATION SYSTEM Donald C. Wellman, Marcellus, N.Y., assignor to Carrier Corporation, Syracuse, N.Y., ware Application March 15, 1957, Serial No. 646,327

. 4 Claims. c1. 62-305 a corporation of Dela- This invention relates to a refrigeration system and more particularly to an improved refrigeration system having novel means for venting the receiver of the system.

Except for small refrigeration circuits wherein the.

refrigerant in the receiver may flash into the vapor state thereby increasing the pressure therein. This increase in pressure in thereceiver impedes the flow of liquid refrigerant into said receiver from the condenser,

causing a backing up of the liquid refrigerant into the.

condenser circuits and thereby impairs the entire operation' of the refrigeration system. A common method of rectifying this condition is to ventthe receiver to the hot gas header of the condenser.

In designing condensers a compromise is drawn between the cost which reflects the amount of surface and circuits in the condenser and the allowable pressure drop of the refrigerant as it passes therethroughl Economic pressures have forced the use of condensers which have a considerable amount of pressure drop therein.

,A situation arises as a result of the aforementioned vent which determines that pressures of substantially equal magnitude exist in the hot gas header-of the condenser and'in'the receiver, The pressure in the liquid header of'thefcondenser is'substantially-lower than the pressure of the hot gas header of the condenser because of the pressure drop in the circuits of the condenser during the condensing action. There is therefore, a reluctance of the refrigerant to flow in the desired path from the hot gas header of the condenser through the circuits of thecondenser into the liquid header and then to the receiver because the receiver, is .at a substantially higher pressure than the liquid header.

V ,The most common method used to overcome this pressure difference is to place the receiver a considerable distance below the condenser so that a liquid head 'is created on. the liquid entering the receiver greater than the pressure drop through the condenser coils, thereby creating a compensating means assisting the flow of re-' frigerant from the liquid header of the condensertinto the receiver.,' Heights of between Sand 20 feet are often indicated as necessary for the satisfactory operation of' the condenser.

I there is a second deflecting wall 2,933,904 Patented A azs, 1960 At first glance, this provision of a small amount of' extended plumbing in a system does not appear to be onerous. However, in actual practice when the condenser is placed on a roof which is a normal practice for evaporative condensers, the architect will bitterly oppose the provision of a platform for the condenser so that the receiver may remain on the roof level. Furthermore, these equipment spaces are usually concealed in penthouses on the roof to preserve the architecturali scheme of the building. Naturally adding between 5 A further object is to provide a refrigeration system having a ventedreceiver which is located at a level sub-- stantially the same as that of the condenser.

, A still further object of the invention is to provide at system employing an evaporative condenser in which the: receiver is vented to the liquid header of the condenser.. Otherobjects of the present invention will become more: apparent from the following description.

This invention relates to a refrigeration system includ'-- ing in combination a compressor, a condenser, a receiver,.

expansion means and an evaporator connected in a cir-- cuit. The condenser comprises a hot gas header con-- nected to the discharge line of the compressor, a liquid header connected to the. receiver and a plurality of cir-- cuits connecting the aforementioned headers. header has a lower opening connected to the receiver and an upper. opening connected to the receiver vent line. Refrigerant which flashes into a vapor is vented to the condenser liquid header where it is again condensed and. returned to the receiver.

I The attached drawings illustrate the preferred embodiment of the invention, in which Figure 1 is a. sectional view in elevation of an apparatus employing the present invention;

Figure 2 is a sectional view of the heat exchanger employed in the invention illustrated in Figure 1; and

Figure 3 is a diagrammatic view of a refrigeration system employing the present invention.

Referring to the drawings there is shown in Figure I an apparatus for evaporative condensing which comprises the housing 2 defining the chamber 2', having an air inletv 3 and an air outlet 4. In the bottom of the housing there is located a sump 5. Adjacent the sump 5 there is located a deflecting wall 6, and adjacent the Wall 6 The heat exchanger 8 is located above the sump 5 and deflecting wall 6. This heatexchanger is the condenser section of'the refrigeration circuit. Such a heat exchanger may comprise a.plurality of parallel rows or r circuits of prime changer is held into place by the support 9 surface or finned tubes.

and may also be suitably bolted to the side walls of the housing 2, by means not shown. The heat exchanger in this particular embodiment is preferably oriented at an angle of between 45 and The liquidi This heat ex-- to a horizontal plane. A cover 3 member 19 having space slots (not shown) is provided for the upper portion of the heat exchanger for a' purpose to be described hereinafter.

Located above the heat exchanger and adapted to cover an area substantially equal to the horizontal projection of the heat exchanger is a distributor plate 10. Above the distributor plate there is located a perforated pan 12.

Located in the sump is a suitable pump 20 driven by a motor 21. The discharge line of the pump is connected to. a line 22 which terminates in the discharge 23; This discharge 23 is slightly below the level of the plate 11 Located above this discharge and attached to the upper portion of the housing, is a disc shaped mem ber 24, the purpose of which will be described hereinafter.

A centrifugal fan 30 is located above the deflecting wall 7. This fan comprises a scroll 31 having an outlet 32 whichcoincides with the outlet 4 of the housing'Z; This centrifugal fan is of the double inlet type. The inlet 33 shown in Figure 1 lies in a plane'substantially normalto the heat exchanger 8 and also normal to the direction of the air flow through the housing. The fan inlet 33' isthe outlet from the chamber 2'. Locatedconcentric with the inlet 33 is a bladed'rotor 34' mounted This shaft 35 is journaled in suitable within the heat exchanger 8, the evaporative cooling" principle is utilized to remove the heat therefrom". Air is induced through the housing '2 by mean's'of the centrifu'gal fan'30. The air passes through the opening 3 in a general horizontal direction, passes over the various circuits of the heat exchanger 8 and is then discharged from the chamber 2 through theinlet 33 of the centrifugal fan 30 and out the fan discharge 32. y

Simultaneously, as the airpasses through the housing 2', water is pumped from the sump 5 through the pump 20 up the line 22 and discharged against the memb'er'24 which casts a stream of water in the pan 12. This pan isprovided with suitable perforations of such a size as to cause spaced streams of water to fall onto the perforated screen 10, which breaks the water into a dense rainfall which drops upon the heat exchanger 8.- The air pass ing through the chamber 2 causes the evaporation of a portion of the water from, the wettedheat exchanger surface resulting in a heat gain by the air stream and a 'corresponding'heat loss by the refrigerant inside the condenser coils which results in condensation of the refrigerant. The amount of heat transfer fronithe refrigerant side to the air stream is approximately equal to the latent heat of evaporation of water.

The water that is not evaporated,- passes from the heat exchanger 8 onto the plates 6 and 7 of the unitand then is directed to the sump 5 to be recirculated.- A-

suitable device (not shown) is provided for compensating for the water'lost as a result of evaporation.

Referring to Figure 1, it is noted'that theh'eat exchanger S comprises a hot gas header 14 andfa liquid header'15. Gas is introduced into the opening connection16 and the liquid condensedin the heat exchanger is"passed'from' the liquid'header through the connection a 17. Anotherconnection 20 is provided, the function of which will be described morefully hereinafter.

Referring to Figure 2Ithere is shown a sectional view of' the'heat exchanger shown in Figure l. The headers 14'and are shown as large cylinders havingsuitable connections 16 and extending therefrom and also having a double row of 8 pass serpentine coils passing from the header 14 to the header 15. It is readily appreciated that such an orientation of circuits provides a large amount of heat exchange surface in a comparatively compact volume.

Referring to Figure 3 there is shown a refrigeration system employing the present invention. This view shows the heat exchanger 8 as it is generally oriented in the evaporative condenser 2. This figure also illustrates the general disposition of the receiver in the refrigeration circuit. The remainder of the elements of the circuit are shown schematically and may be varied without going beyond the scope of the present invention. Considering the circuit, a compressor 45 is provided which is indicated as a reciprocating compressor. It is apparent that other types of compressors may be used. The

discharge of the compressor passes through the line 46 which passes hot gas into the hot gas header 14 of the heat exchanger 8. The hot gas is introduced into the header through the connection 16. The gas is condensed within the" various parallel serpentine circuits of the heat exchanger 8 and collected in the header 15 and discharged through the lowermost opening 17. It will be noted that in thisview the header 14 is parallel to the header 15, both headers being oriented at an angle' to a horizontal plane. The liquid header 15 is partially beneath the hot gas header 14. The liquid is dis cha'rged from the condenser through the liquid line 47 and'introdu'ced-into' the receiver 49 wherein the liquid is passed'through the liquid line 52 to the expansion valve 53. This valve may be of the thermo-expansion type being connected by suitable line 54 to a bulb 56 located adjacent the suction line 59 of the refrigeration" system. The refrigerant'passes through the expansionmeans53 through the line 57 to the evaporator 58 which provides-for the load of the system. The gas passing-- from theevaporator-58 passes through the suction line 59 and returns to the compressor 45 thereby completing the-circuit.

The receiver is provided with a suitable line 51 which This line 51 is connected to the vents gases therein. I vent opening 20 of the heat exchanger 8 and also to the valve 60 by means of the line 52.

Considering the operation of the present invention, hot' gas is'discharged from the compressor into the discharge line 46. The hot gas is introduced into the center section of the hot gas header 14 through the connection 16.

The gas as it enters the header will pass up and down;

said header into the

various circuits

40 and 41. The refrigerant passes through the circuits and the previously described evaporative cooling effect takes place wherein the air passing through the unit gains in total heat content by' evaporation of water from the heat transfer surface; heatof evaporat'ion is supplied to'the water film':

by the'warm condenser surface, resulting in a heat loss by the refrigerant inside the condenser coils causingcoirdensation of refrigerant in the

circuits

40 and 41 which subsequently collects in the liquid header 15.

The liquidwhich collects in the liquid header 15 passes downwardly due to'the effect of gravity and collects:

about the opening 17 which is connected to the liquid leg 47 which is, in turn, connected to the receiver '48.

Aidist'ance H is indicated in this leg 47 for a purpose to be describcd'more'fully hereinafter. The'liquid enters the receiver 48 and forms a pool 49. therein having" agas space '50 thereabove. As previously mentioned this receiver is probably located in a hot machinery room or is exposed to'the sun on the roof of the building.

Since the temperature of the receiver is substantially higher than the temperature withinthe condenser itself, there will be atendency of the liquid pool 49 to flashthe liquid refrigerantinto a vapor form. The pressure:

within the receiver may increase to a point which will cause liquid' refrigerant to back into the condenser cir;

cuits rather than to pass into the receiver as a result of the localized high pressure. To remedy this circumstance, the receiver is .normally vented by a separate vent line. The receiver therefore, hasv a means of relieving the pressure therein. 'In the present invention this is accomplished by the connection of the line 51 with the vent opening 20.

The present vent is unique'in that it is connected to the liquid header 15. This is a result of the unique design and disposition of the coil used herein. As previously mentionedthe header 15 is placed at an angle inorderto facilitate the evaporative cooling method described inconnection with Figure i. As the result of the unique orientation of the header 15, all the refrigerant will flow downwardly toward the opening 17 which is the loweremost opening in the condenser. This leaves the upper portion of the header 15 substantially dry and therefore there is no danger of liquid passing into the vent and subsequently into the receiver through the vent line 51. The flashed refrigerant from the receiver passes through the line 51 and is then introduced through the vent opening 20 into the header 15. This gas then has an opportunity to pass into the liquid header and a portion of the lines comprising the

circuits

40 and 41 where the gas is recondensed and returned into the header 15 where it is under the influence of gravity, thereby passing down toward the opening 17 and reintroduced into the receiver 48.

The remainder of the refrigeration circuit functions in a conventional manner. The liquid passes from the receiver 48 into the line 52, through the expansion valve 53, into the evaporator 58 where the liquid is substantially returned to the gaseous state by the heat exchange process with the load of the system. The gas is .then passed through the suction line 59 and returned to the compressor. The vent line 51 is also connected to line 52 having a valve 60 and a cap 61. It has been found that this particular connection is a convenient place for providing an opening to purge or charge the refrigeration system.

Considering the theory of operation of the disclosed system, it will be noted that the receiver is operated at a pressure substantially the same as the pressure within the liquid header 15. This is a result of the venting of the receiver to this particular header by means of the line 51 and the connection 20. As a result, only a slight amount of head is required in the line 47 to pass the liquid into the receiver, this required head being equivalent to the pressure loss in the line 47 itself. The present system, when contrasted with previous systems highlights a distance H (shown in Figure 3 but not required in the system shown) which may be of a magnitude of between 5 and 20 feet. a

In prior systems the entire liquid header is operated in a wet condition so that venting the receiver to the header is not possible without the danger of liquid passing through the vent line. As a result the receiver is vented to the hot gas line which was at substantially the discharge line pressure of the refrigeration system. In such systems, a substantial pressure drop takes place through the many small circuits which pass from the header 14 to the header 15. In order to vent the re ceiver, the receiver is connected to the hot gas header, thereby putting the hot gas header and the receiver at substantially the same pressure. However, as a result of the pressure drop through the condenser coil, the liquid header of the condenser is at a lower pressure than both the receiver and the hot gas header. There is therefore a reluctance of the refrigerant to pass from the lower pressure liquid header to the receiver. To overcome this reluctance, a compensating means is provided between the liquid header and the receiver. The

' most convenient compensating method is to provide a head equivalent to distance H of Figure 3 which provides a pressure increase in the line at least equivalent to the pressure drop in the condenser circuits, thereby favoring the passage of liquid refrigerant from the liquid header to the receiver.

It is appreciated that as a result of the present invention no substantial difference in height need exist between the receiver and the condenser since the receiver is operated at substantially the same pressure as the liquid header of the condenser. It will be also noted that the present invention is not restricted to evaporative condensers, but can be applied to most refrigeration systems wherein a receiver is utilized and where the receiver requires venting.

-While I have described a preferred embodiment of the.

invention it will be understood that the invention is not limited thereto since it may be otherwise embodied within the scope of the following claims.

I claim:

1. In a refrigeration system, the combination of a compressor, a condenser, a receiver, expansion means and an evaporator connected in a circuit, the condenser comprising a liquid header angularly disposed with respect to a horizontal plane and a hot gas header located parallel thereto, a plurality of serpentine circuits connecting said headers, said liquid header partially lying below said hot gas header, said liquid header having a lower opening adjacent the lowest portion thereof, means connecting said lower opening to said receiver for passing liquid refrigerant thereto, and vent means extending from said receiver, said liquid header having a vent opening located adjacent the highest portion thereof and being connected to said vent means from the receiver whereby refrigerant that vaporizes in the receiver passes into the condenser to be re-condensed and passes to the receiver in a liquid form through the aforementioned liquid line.

2. In an evaporative condenser, the combination of a housing, means for passing air through said housing, a heat exchange member located in said housing, means for passing a liquid filmv onto said heat exchange member, whereby the air passing therethrough will cause an evaporative cooling effect upon said heat exchange member, said heat exchange member comprising a hot gas header angularly disposed with respect to a horizontal plane, a liquid header located parallel and partially below said hot gas header, a plurality of serpentine shape circuits connecting said headers, a liquid discharge opening adjacent the lowest portion of the liquid header and adapted to be connected to the receiver of a refrigeration system, a vent opening located adjacent the uppermost portion of the liquid header, and spaced from said discharge opening therein, and an opening into said hot gas header, a vent line connected to said vent opening at one end thereof and adapted to be connected to a receiver at the other end thereof whereby vaporized refrigerant from a receiver may be re-introduced into the condenser through the vent opening and be condensed and passed from the condenser through the liquid opening in the liquid header.

3. A refrigeration system comprising a compressor, a condenser, a receiver, an expansion device, and an evaporator and means connecting the named components in that order to form a refrigeration circuit, said condenser comprising a liquid header and a hot gas header connected by heat exchange tubing, said liquid header having upper and lower openings spaced therein, said means connecting the components including a liquid line joined to said liquid header at said lower opening therein and connecting said liquid header to said receiver, andmeans to facilitate flow of liquid refrigerant from said liquid header through said liquid line to said receiver, said means comprising a vent line joined to said liquid header at said upper opening therein and connecting saidliquid header to said receiver at a region therein wherein flash gas is enabled to accumulate to thereby vent flash gas in said receiver'back to said condenser for recondensation thereof and to prevent the pressure of flash gas in said receiver from blocking flow of liquid refrigerant through said liquid line.

said receiver zitga region therein yvhi ein" fia'sh s? enabled to accumulate to carry flash from saidi' ceiver back to the liquid header of said co'lidensf;

Ref erencesCited in'the me of this pat'iii UNITED STATES FATEN'TS I