US2324627A - Refrigeration - Google Patents

Description

July 20, 1943.

REFRIGERATION Fi le' d Aug. 1.1940

2 Sheets-Shea; l

INVENTOR. wow Jm ATTORNEY. 3

, REFRIGERATIO u T Filed Aug. 1, 1940 -2 Shaets-Sheet 2 INVENTOR.

ATTORNEY.

Patented July 20, i

UNITED STATE assist? auramm'rron Walter Jones, Princeton, N. 1., asslgnor to camel-I Corporation, Syracuse, N. Y., a corporation of Delaware Application ism-t i. rm, Serial No. 349,155

14 Claims. (01. 82-2) This invention relates to refrigeration, and

. more particularly to features ofconstructionand 'methods of operation employed in connection with a centrifugal refrigeration compressor a'ssembled in combination with an evaporator, a

condenser and related auxiliary elements.

. Important features'of the invention reside in the arrangement of a condenser superposed in position above an evaporatorythe, discharge of compressed refrigerant vapor from the compressor into the condenser in an upwardly direction; the wetting of condenser surfaces to eliminate superheat from incoming vapor discharged into the condenser; the regulation of flow of cooling medium within the condenser to facilitate concentration of non-condensible gases at an upper level of the condenser; the concentration of noncondenslble gasesin a quiet zone in which a relatively small percentage of condenser tube surfaces are subjected to air or non-condensible gas film; the distribution of incoming refrigerant vapor over a tube bundle, and prevention of vibrational stress at the points ,of entrance of the.

vapor; the segregation of condenser areas by a baflle arrangement to protect the tube shell, increase the velocity of the vapors in their course through the shell and yet provide a relatively quiet zone to preventdiffusion of non-condensible gases collected therein; facilitating removal of condensed refrigerant from the, condenser shell; supporting removable finned tubes in cupport sheets while enabling such tubes easily to be removed; indicating accumulations of noncondensible gases and providing for emcient purging or removalthereof under a manual or automatic control; and recovering refrigerant from a mixture of non-condensible gas and refrigerant for reuse in the refrigerant cycle.

These and other features will be apparent from the following detailed description of atypical form of the inventionto. be read in connection with the accompanying drawings, in which:

Fig. 1 shows diagrammatically applicant's general arrangement of compressor, evaporator and condenser.

Fig. 2 diagrammatically represents certain features of the condenser plus the method of indicating accumulations of non-condenslble gases therein. t

Fig. 3 diagrammatically shows a condenser similar to that ofFig. 2 inassociation with a p rse recovery system and a modified arrange ment for indicating accumulations of non-condensible gases; and

Fig. 4 illustrates applicant's method of supi'rigerant such as carrene No. 2(CF013), conporting finned tubing is a tube sheet positioned intermediate the ends thereof.v

. Considering the drawings, similar designa tions'referring to'slmilar parts, numeral I designates an assembly of apparatus including a centrifugal compressor employing a suitable re- 'dens'er 1 and evaporator or cooler l, all said olemerits being suitably aligned and assembled upon a bed! having two longitudinal base portions ll and II. Longitudinal base portion Ill may be mounted upon two support points i2, one adjaf cent each end of the base portion, whereas section ll may rest upon a single support point I! positioned midway of the base portion, between points I! of base portion III. This three point support arrangement assures'the alignment of elements 6, I and i regardless of slight irregularities in the surface on which bed 9 .is supis as follows: The brine, or water to be cooled;

flowing through the tubes is warmer than the refrigerant in the'shell surrounding the tubes.

As a result, the refrigerant is evaporated at a v temperature corresponding to the.pressure in the evaporator. The refrigerant; in resultant vaporous form, passes througheliminators it into the suction of the compressor 8. The compressor normally has aplurality of stages of compression, and the compressed: gas discharged from the last sta'ge enters the 'condenserwatya point proximate" the bottom of: the condenser as shown. The refrigerant discharged by the com,- pressor int the condenser, condenses on the out-, side of tubes I! at a temperature correspond! ing to the condenser pressure, the'heat of condensation being transferred to the condenser water. The liquefied refrigerant from theconde'nser drains down an inside conduit into an economizer, described m i U. S. Patent No. 2,277,647. From the economizer, which may or may not be incorporatedwith applicant's structure, the refrigerant in liquid form is routed to the cooler to complete the cycle. V

The compressed refrigerant gasjenters the con; denser at point I! near'the bottomthereof, rushing upwardly. Perforated sheet ll prevents too- I preventing vibrational stress at the points of entrance. The perforations permit some of the gas to contact the tubes situated proximate the point of entrance, unlike other baflling arrangements-which might make this portion of the 6011-.

denser surface comparatively useless. The cooling water is routed through tubes I5 in one or 'more passes, preferably flowing from top to bottom or from'upper levels to lower levels. The

- result is that with applicant's bottom intake arrangement, the gas in contacting the upper tubes 1 tively wetting the lower tubes, and this eliminates superheat from the entering gas before such gas contacts the tube cooling surfaces. Without such and this will result in a shower ferrous material. Baiiie it may extend for a can assess:

water vapor in the presence of air at the upper part of the shell. The shell is usually made of siderable distance along the top of the shell cover the area wherein non-condensibles are col lected and thereby protects the upper part of the shell from corrosion. By extending about twothirds of the distance across the shell it serves to zone thereabove wherein the non-condensibles are collected. Turbulence and velocity are at'a minimum in this zone, thereby facilitating connpwardly discharge of refrigerant and consequent showering of condensate,-the rate of heat.

transfer from the gas to the cooling water inside the tubes would be much lower.

' The refrigerant normally used in applicant's system when discharged into the condenser, is in the form of a dense gas of. high molecular weight. Any non-condensible gases present in the condenser are less dense and of lower molecular weight. The admission of the gas into'the condenser causes turbulence in the lower part of the condenser. with the arrangement of upwardly dischargeof gas and downwardly flow of cooling water as shown in Fig. ,1, which results in this turbulent condition, the lighter non-condensible gases rise to the top of the condenser. By arranging the cooling water inlet at the top condensation takes place to a greater degree than if warmer water were circulated at this point, and this thorough precipitation of refrigerant gas results in a concentration of non-condensibles at the top of the condenser substantially free of refrigerant at the upper point-of accumulation. Thus, air and water vapor (non-condensibles) are collected in a relatively small space so that a small percentage only of tube surface is subjected to air (and other non-condensible gas) film, leaving a greater proportion of condenser tube portions free from such film which cuts down heat transfer efllciency.

Furthermore, by arranging for precipitation of refrigerant in a downward shower, the turbulence in the lower portion of the condenser which results therefrom is maintained vigorouslyto prevent air film from forming on such tubes; this film destruction or breaking up process being vigorous and continuous. Also, the condenser tubes, as is also the-case with the evaporator tubes, are provided with extended surfaces or flns. Since these fins produce in the aggregate a greater amount of surface than plain tubes, the air film where it does affect some of the tubes is much thinner than if plain tubes were employed with the result that the reduction in heat transfer emclency is held to a minimum.

The use of fin surfaces of the type, for example, shown in Fig. 4, provides a large amount of surfacesrenabling the use of a. much smaller shell. Consequently, much greater velocities over the surfaces in the smaller space are obtained and this further promotes turbulence and heat exchange compared to that obtainable with gas moving at a slow rate. The fast moving gas provides another advantage in that it serves to reduce the thickness. of such .air'film as maybe formed at tube surfaces to a minimum.

Baille I9, as shown, is located within the tube bundle in the condenser. .11; is preferably made of non-ferrous material immunefrom at'tack b centration of the non-condensibles,'snd conversely prevents diifusion of the non-condensibles. As is pointed out more clearly in Fig. 8. the

condenser may be provided with an inclined eiement or plate 2. for draining condensed refrigerant to condenser discharge point 2|. The condenser structure essentially consists of a shell 22. and includes tube sheets 23 and intermediate vtube-supporting sheets 24. The tubes, at their ends, may be suitably enlarged or rolled into tube sheets 23 and may be supported at support sheets 24 by enlarging the fin tubing at their points of contact 25 with the support sheets. The

result is that the finned surfacesat the points of contact with support sheets are held in nrrn frictional engagement, not easily separated unless the tube is pushed through the support sheet with some force.

For removing the non-condensiblesfroni the top of the condenser, a purge-recovery arrangement is provided with an eflective means for indicating the extent to which air and other noncondensibles may be present. An indicator .01 gauge 28 is provided. It has two hands. one of. which is preferably colored redto indicate the total'pressure in the-condenser and the that used in the refrigeration cycle, contained in a thermal bulb 21 exposed to the condensing temperature. This bulb may be located in a compartment It at the point of evacuation as shown in Fig. 2, or may be positioned for immersion in the refrigerant normally flowing from the bottom .-of the condenser, as shown in 15g. 3. When air is pump, suitably driven as by" motor 38 maybe;

controlled manually or automatically through control 34, which is operative responsive to a I conduit u and'in doing sowill-pull a quantity ofpredetermined difference in pressures within-the condenser. As a result, when evacuationis required, pump I! will purse the system through refrigerant with the non-condensibles. The compressed gas and non-condensibles will be disdesign, the condensed refrigerant and the compressed non-condensibles'flowing into receiver 36. The non condensibles will be relieved from the receiver through .valve 31. *Float valve 38 will control the return of recovered refrigerant to the system through line 39. l

Since many. changes in construction, arrangement and operation may be made in the embodiments herein shown and described, without in any way departing from the scope of the invention, it is intended. that the foregoing-descrip tion is to be considered as illustrative and not in.

a limiting sense.

I claim: V 1. A refrigerant condenser of the shell and tube type, comprising. a tube bundle within the shell, means for admitting compressed refrigerant gas into the condenser at a pointproximate condenser, refrigerant and non-condensible gases within said'condenser, means for gauging the 'pressure within saidcondenser correspondingto the condensing temperature of the refrigerant within'the condenser, meansfor-gauging the total pressure within the condenser, and a-devicefor indicating the difference between said pressures. 6. In asystem of the character described a condenser, a thermal bulb within the condenser,

means operative in response to the change in temperature of said thermal bulb for indicating a pressure corresponding to the condensing temperature of a refrigerant in the condenser, means for measuring the total pressure in the condenser,

the bottom of the condenser and in an upwardly direction whereby the gas is directed upwardly in contact with the tube bundle, and means for circulating a cooling fluid within the tubes of the bundle in such manner that the gas will be condensed in the upper part of the shell causing a shower of liquefied refrigerant to fall upon and wet tubes lower in the shell, he lower part of the shell comprising a turbi'lent zone in which a violent boiling action takes place, the evaporation of liquefied refrigerant falling on tubes adjacent said means for admitting refrigerant gas to the condenser causing elimination of superheat from refrigerant gas entering the condenser and contacting said tubes, and means providing a relatively quiet zone in the upper part of the shell to which non-condensible gases relatively lighter than the refrigerant rise.

2. A refrigerant' condenser of the shell and tube type, comprising a tube bundle within the shell, an. inlet for admitting refrigerant gas upwardly into the condenser to contact the outer surfaces of the tubes of the bundle, means for pressure units.

ber of pressure unitsto cause said means automatically to operate until the total pressure in the condenser falls to a pressure substantially corresponding to the partial pressure exerted by the refrigerant inthe condenser.

9. In a system according to claim 5, a thermal bulb in one portion of the condenser for exerting a pressure corresponding to the condensing temadmitting cooling fluid into said tubes so that it flows downwardly within the bundle from an upper to a lower level in the condenser, said routing )f refrigerant and cooling fluid causing a shower of condensed refrigerant to falldownwardly upon and wet the tubes adjacent the bottom of the condenser so that a turbulent zone iscreated in which superheat is removed from refrigerant gas admitted into the condenser in contact with said wetted tubes, means for relatively segregating a portion of the tube bundle at the upper part of the shell from the remainder of the tube bundle whereby a relatively quiet zoneis maintained in the upper part of the condenser, the

agitation in the turbulent zone causing a wiping away of air and other non-condensible gases from the tubesin said zone, said air and non-condensible gases rising into the quiet zone.

3. A refrigerant condenser according to'clalm 2, having 'finson the outer tube surfaces, said fins providing a greater area of heat exchangesurface whereby the air and non-condensible gases collected in the upper part of the shell will be spread over a greater area of surface and affect a relatively small proportion of the total heat exchange surface of the tubes in the bundle.

'4. A refrigerant condenser according to claim 1, having means on the outer surfaces of tubes of the condenser for increasing the area of heat exchange surface in the condenser whereby the size of 'the shell may be decreased resulting in increased refrigerant gas velocity through the,

shell. v 5. In a system of the character described a perature of a refrigerant in the condenser, a pressure conduit connecting said bulb to said indicating device, another conduit connected to another portion of the condenser and to said device for transmitting to the device the total pressure in the condenser, and a third conduit for withdrawing from the condenser non-condensable gases exerting a pressure in said second conduit.

10. In a system of the character described, a con denser, means in the bottom of the condenser for facilitating delivery of condensed refrigerant to a point of discharge, said means comprising an inclined bed running substantially the full length of the condenser, and an opening in the bottom of the condenser connecting with the inclined bedfor dischargingffro'm thecondenser refrigerant flowing from the inclined bed.

11. A refrigerant condenser comprising a shell, a plurality of tubes within sald shell, said shell having an inlet opening for refrigerant gas located in the lower portion thereof and an outlet ,opening for condensed refrigerant located substantially at the bottom thereof, said inlet openng being arranged to deliver refrigerant gas passing therethrough in an upwardly direction within said shell and in contact with said tubes, ii. baflle within said shell, said shell having in the top thereof a relief outlet for non-condensible gases, said baffle being disposed between said inlet opening and said relief opening, and extending obliquely downwardly from the inner'surface of the upper portion of said shell covering in excess of fifty percent of the diameter of the shell to form substantially a barrier between the area in the condenser adjacent the inlet where conditions of turbulence prevail and the area i adjacent said relief opening wherein non-condensible gases are accumulated and where a relatively quiet condition exists.

12. A refrigerant condenser as defined in claim of a protective lining provided for the innersur- 11 in which said bafile extends substantially twoface of the upper part of said shell. thirds of the distance aCl'Fo'S said shell to in- I 14. A refrigerant condenser as defined in claim crease the velocity of refrigerant travel over a 11 in which said baffle lies in a plane substantially major part of said tubes. 5 perpendicular to the line of travel of retrilen'nt 13. A refrigerant condenser as defined in claim entering said shell through said inlet openlnl. 11 in which said baflle constitutes an extension WALTER JONE.

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