US2658357A - Refrigerating system - Google Patents

Description

V 9 vfw. SMITH REFRIGERATING SYSTEM 2 Sheets-Sheat 1 Filed May 17, 1950 INVENTOR. we 70/? 14 SM/Tf/ A 7'7'0RA/E) Nov. 10, 1953 I. W. SMITH REFRIGERATING SYSTEM 2 Sheets-Sheet 2 Filed May 17, 1950 Fig.2

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INVENTOR. V/CTOR W. \SM/TH Patented Nov. 10,- 1953 REFRIGERATING SYSTEM? VictorW. Smith, Trenton, N. J'.,, assignor to ,0. Va Hill & Company, Inc., Trenton, N. .L, a corporation of New Jersey Application- May"17', 1950,; Serial. ,No. 162,501-

3 Claims.

Thiseinvention relatesto refrigerating. systems of th,e.,type whereina compressor, condenser and evaporator are employed and means are, provided forydefrostingthe. evaporator periodically. This application isa continuation-invpart of my copendingapplication .Se-rialNo. 752,031 filed .June 3, 1947, now. Patent, No. 2,555,161, May 29, 1951;

Itis. alcha-racteristic of all refrigerating sy tems in. which the. evaporator is, raised to an elevatedytem-perature for defrosting purposes, that the. initial period of refrigeration following. a defrosting cycle imposes aheavy load upon the com-. pressor, condenser and other; elements of, the system. This is due to the fact that theevaporator 1 isrelatively: warm, at the conclusion of the de frosting cycle-and relatively largaamountsoii refrigerantare introduced, into. the evaporator. The refrigerant. gas returning to the compressor under such, conditions is at a higher temperature and pressure than-usual-and as a, resultlthe re.- compression of the, refrigerant gas raisessit to an abnormally high temperature andpressure. Thezcondenser is then v called upon, to. dissipate an excessiveamount of heat, so that it. may be, at least temporarily, overloaded and its tempera turerisescausing backpressure tobe imposed on the systemlandyplacing, aheavy load on the motor bywhich thecompressor is. driven.

In: the systems described in said co-pending applications.,defrosting of the evaporator is accomplished-by: passing, hot refrigerant. gas from the compressor to theevaporator, by-passingthe condenser, during i the: defrosting cycle whereby ice: and frostare melted .fromthe coils, fins, drip p n nd. adja urf ces of the ev porat r.- The refri erant is. partially condensed by ivin up heat. .to the evaporator. and, therefore means areinterposedbetween the. -evap or ator and the compressor. to re-evaporatetheliquid refrigerant beforeit reachesthe compressorn In one form of the invention disclosed in said application Serial No. 752,031, now PatentjNo. 2,555,161, May 29, 1951, the coils or passages of the revaporizer are, arranged in heat exchangingrelation with thecoils of the condenser and in the construction of application Serial No. 109,335, now Patent No. 2,632,303March 24, 1953., a restrictororexpansion valve is. located adjacent the inlet to the. revapo rizer to insure expansion andvapori zation of the returning. liquid refrigerant. Further, in both of said applications ambient air is. blown over both coils, causing moisture from the air, tocondense onthe coils of the revaporizer, and give up its latent heat of. vaporization to the-evaporating liquid, refrigerant.

Inuaccordancewith the present invention such heat exchange between the revaporizer and the condenser is further utilized to reduce the load on the. compressor duringthe initial stages of the refrigeration, cycle. This is accomplished by arranging the coils, of the. revaporizer and condenser insuch heat exchanging, relation that the condenser coils wili be cooledsuificiently by expansionof gas in the revaporizer during the defrostcycle tocause moisture to deposit. and ice to formn. the. nden er. Thereaf r dur n the. initial periodof the refrigerating cycle the condenser gives up heat in melting suchjce or frost, and evaporating themoisture whereby, the rate of heat dissipationbythecondenser is in;- creased' at the very time wh n overload naof the condenser and, other. elements of the. system would ,otherwise, tendto. occur.

Th unlimited availability, of. air O .he&ffi.. X- change-with the revaporizer, also permits. the. defrosting-operation, of the present. invention -t0..be prolonged sufficiently .to ,cause the. evaporator, to function as; a? heat" ejecting meansuorv radiator when-desired. The temperature. of airin an enclosure or conduit. cantherefore besraised. or lowered as required by reversible action ofthe evaporator in anysituation where -it is desiredto maintain-1 temperatures within predetermined limits.

Thaccnstructionof the present invention fur.- ther makesfitpossible to reduce thesize andcost of the condenser and revaporizenand 'the Whole assembly may be made morecompactand simple inconstruction.

Oneof the objects of the:presentinven-tien is to provide an improved 'form of defrosting equipment for use in refrigerating systems of thetype employing a compressor, condenser and;evaporator.

Another objectof'the invention is to: reduce the loads towhichthe compressor, condenser and other elements of refrigerating systems are subjected during the initial stages of arefrigerating cycle following a defrosting cycle.-

A furtherobject of the invention is to provide an improved formof condenser-revaporizer assembly for use in refrigerating systems.

Anotherobject of the invention is to provide a system wherein continued and reversible heat transfer through the evaporator is possible.

These and other objects 1 and features of the present. invention'w-ill appear from thefollowing description thereof inwhich reference is made to the figures ofthe accompanying drawings- In the drawing:

Fig. 1 is a diagrammatic illustration of a typical form of refrigerating system embodying the present invention;

Fig. 2 is a perspective view of a preferred form of compressor, condenser and revaporizer assembly adapted for use in the system illustrated in Fig. 1;

Fig. 3 is a vertical sectional view of the condenser-revaporizer shown in Fig. 2;

Fig. 4 is a sectional view of a detail of the construction taken on the line 4-4 of Fig. 3; and

Fig. 5 is a horizontal sectional view of one of the headers taken on the line 55 of Fig. 3.

In the refrigerating system illustrated in Fig. 1 there is a compressor 2, a condenser 4, an expansion valve 6, an evaporator 8 and revaporizer coils i0. These elements are connected together in series and during the normal refrigeration cycle hot refrigerant gas from the compressor flows through the high pressure line [2 to the condenser 4 where it is cooled and condensed to a liquid. The liquid refrigerant passes from the condenser to the receiver M from which it is supplied through the refrigerant line It to the expansion valve 6. The refrigerant passing the expansion valve is vaporized in the evaporator 8 where it takes up heat from the air and surfaces adjacent the evaporator. From the evaporator the refrigerant gas flows through the return line l8 to the revaporizer I0 and returns to the intake side of the compressor through the low pressure line 20.

For defrosting purposes and to permit the evaporator to function as a heat ejecting means or radiator, a by-pass line 22 is provided and extends from the high pressure line H to the evaporator 8 so as to by-pass the condenser, receiver and expansion valve. A control valve 24 is located in the by-pass line 22 for initiating and terminating the defrosting operation. The control valve may be actuated by a suitable means indicated generally at 26 and consisting of a time clock, pressure or temperature responsive means or a combination of these or other control devices.

During the defrosting operation hot refrigerant gas passes from the compressor 2 and high pressure line I 2 through the by-pass line 22 to the evaporator 8. Heat is thus supplied to the evaporator and to the drip pan 28, drain 2!! and other surfaces in heat exchanging relation with the by-pass line to melt the ice and frost thereon. In giving up its heat to melt the ice the not refrigerant gas is cooled and at least a portion thereof is generally condensed to a liquid. The mixed gas and liquid refrigerant flows through the return line l8 to the revaporizer Hi. It is preferable to provide a restrictor 30 in the return line adjacent the revaporizer [0 as shown and described more fully in my co-pending application Serial No. 109.335 filed August 9, 1949, now Patent No. 2,632,303. Air is blown over the coils, fins, and other surfaces of the reheater l0 by means of a blower 32 whereby moisture contained in the air is caused to condense on the surfaces adjacent the revaporizer giving up its latent heat of vaporization to the liquid refrigerant whereby the refrigerant is completely evaporated before it returns through the low pressure line 20 to the compressor 2.

At the conclusion of the refrigerating cycle the valve 24 in by-pass line 22 is closed so that refrigerant gas again passes from the compressor to the condenser. However, by arranging the coils of the condenser and revaporizer in intimate heat exchanging relation the moisture which was condensed and the ice which has accumulated on the surfaces of the condenser-revaporizer unit absorb heat as latent heat of fusion and latent heat of vaporization from the hot gas flowing to the condenser. Sensible heat is also given up by the condenser to the coils, fins, and other surfaces of the revaporizer. In this way there is immediate and unusual dissipation of heat by the condenser during the initial period of refrigera tion following the defrosting cycle and until the ice and moisture on the surfaces of the condenserrevaporizer unit has been removed. Thereafter the demand for heat dissipation by the condenser is reduced and the normal flow of air from the blower 32 over the coils and fins of the condenser is adequate to condense the refrigerant and prevent overloading of the system.

The construction shown in Figs. 2 to 5 of the drawings embodies a condenser section 34 and a condenser-revaporizer section 38. The refri erant gas from the compressor passes from the high pressure line I2 to the small header 38 of the condenser section and then flows in parallel through two sets of coils 40 and 42 which extend back and forth from the upper to the lower portion of the condenser section 34. These coils are provided with fins 44 for increasing their heat exchanging surface, and the lower ends of the coils 40 and 42 turn upward as shown at 48 and 48 and enter the side of the header 50 shown at the right hand side of the condenser-revaporizer section 38.

As shown in Fig. 5 the header 50 is preferably formed of an outer U-shaped channel member 52, a reversely facing intermediate channel member 54 and an inner channel member 58. These channel members are brazed or otherwise connected together to form an inner header section 58 and an outer header section 80. The opposite end of the condenser-revaporizer is provided with a similar header 62 which is formed with an inner header section 64 and an outer header section 66. Two series of tubes of different diameter are arranged one within the other and extend between the headers 50 and 62 with the tubes 68 of larger diameter communicating with the inner header sections 58 and 64 and the tubes 10 of smaller diameter communicating with the outer header sections and 66. Webs or loops of conducting material I2 radiate from the inner tubes 10 to the outer tubes 68 providing effective heat conductivity therebetween while imposing very little obstruction to the flow of gas through the space between the tubes. The tubes are also provided with the usual external fins 14 to provide added heat transfer surfaces over which air from the blower 32 is passed.

The flow of condensing refrigerant from the compressor through the condenser-revaporizer during the refrigerating cycle takes place as follows:

After passing in parallel through the coils 45 and 42 of the condensing section the refrigerant flows upward through the vertical tubes 46 and 48 and enters the side of the header 50 at the points 16 and 18 in the inner header section 58 between an upper partition 80 and an intermediate partition 82. It then flows in parallel through the space between the tubes 68 and 10 which form the passes indicated A and B to the inner header section 64 of header 62. The latter section is provided with an intermediate partition 84 which serves to cause the refrigerant received from both passes -A and B' to return to: header: SOTthrough the single pass A- lowerpartition: 86; inathe inner section-of header ifl separate =pass-D from: pass Eand therefore-the reirigerant'flows through pass D' to header "62 and back-through passrliiito the chamber Stbelow'partition=86: From chame ber-BB the new fully condensedcancl'zliquifiedtzree frigerant passes through the liquid Iline 991110 ,:the receiver M.

The refrigerant gas returning; to; the comev pressor 2 from the evaporator 8iflowsthrouglr return line l8 and "restrictor -3it so: asitolenter the outer header section"fifi f'of'headertzi. From the latter header the refrigerant-flows in'parallel through the smaller diameter" tubes 11s.: to 1 the outer-header section-fillofxthe headerfiiiiandfthen flows upward through the port 92: and itheyupe permost pass 94 which functions asra: .de-superheaterr The vaporizedandiconditioned refrigerant gas then flows to the'low"pressureline- 29 leadingto the intake sidc'of compressor 2'.

The'restrictor valve 30 through which the returning refrigerant'enters the-header 62. is preferably of thetype shown and described in=co+ pending application S'eria-l'No: 199,335 andoperates in response to th'epressureof the-gas. on the intake-side ofthe compressor to imposelittle or no resistance-to the-flow: of ref-rigerant: therethrough during the normal refrigerating cycle when the pressure of gas in the evaporator and return lineis relatively low. However, when the pressure on the intake side of the compressorv'is relatively; high, as it isduring the defrost cycle, and during the initial period of refrigeration following thedefrost cycle, thevalve 30 tends to close and functions as'an expansion valve to insure vaporizationlof the liquid refrigerant in the tubes it of the condenser-revaporizer section 35.

With this construction heatlis supplied-, du-ring they-defrosting cycle, to the refrigerant flowing through the, smaller tubes lit by conduction through the webs 12 andithe exposed surfaces of thelarger. tubes 68 and fins, Ml Air 'isbloiwn over the condenser and the larger tubes of the condenser-revaporizerunit by blower 32, which is shownin Figs. 1 and 2. The-liquid refrigerant flowing through the revaporizer tubes during the defrosting cycle is expanded in a gaseous form by passage through the nearly closed restrictor 39 and generally is reduced thereby to a temperature below 0 F. The temperature of the larger diameter tubes 68 is therefore reduced by the flow of heat through webs I2 and as a result moisture from the air condenses on the surface of the larger tubes and fins giving up its latent heat of vaporization t0 revaporize the refrigerant returning to the compressor through the tubes Hi. There is little or no flow of refrigerant through the condenser and larger tubes 58 during the defrosting cycle so that as the defrosting cycle continues the condensed moisture on the exposed surfaces of the tubes and fins generally is congealed to form ice or frost whereby additional heat is given up as latent heat of fusion of the moisture condensed from the air.

In most cases it is this latent heat which is relied upon primarily for revaporizing the returning liquid refrigerant during the defrosting cycle, since it can be readily shown in a typical installation that nearly 300 times as much heat is given up to the refrigerant as latent heat of vaporization of moisture condensing from the air and freezing on the exposed surfaces than is given up as sensible heat in cooling the air flowing over the unit. The condensed and frozen moisture continues: to": accumulate on: tubes 68. and fins -"ltcduringrthe defrosting operation and:

therefore -,builds up: :to serve: in t effect I as. a cold storage means: which thereafter operates automatically to increase'theiefiective capacity of the condensing: elements when hot refrigerant gas agairr isz-passed-to: the condenseron renewing thesrefrigeratingcycle'.

Thereafter 'whenthe refrigerating cycle: is initiating the-hot:refrigerant gas from the compressor: first-r flows through the; condenser section M a-rid then flows through the ice covered tubes 68 of thecondenser-revaporizer unit. The: ice and frost which has accumulated on-the exposed surfaces is t-hen' melted; absorbing latent heat of fusion; andithei resulting moisture is evaporated absorbing latent heat of vaporization;v The: ac.- celerated "rate. of j heat absorption resulting from such 'meltingr and evaporation insures more rapid condensation of the refrigerant during the initial period-of refrigeration following a defrosting. cycle andareduction in'the backpressure imposed on the compressor and condenser; At the same time the refrigerant gas returningto the compressor throughthe-restrictor and the inner tubes in of the condenser-revaporizer:serve to cool th condensing refrigerant further withdrawing, heat therefrom. Such unusualdissipation of'heatby the'condenser continues until all of the ice, frost and moisture on the surfaces of the tubes. Stand fins Mi has been dissipated. However, by'that time the temperature ofthe evaporator, will be reduced and the load on theqcompressor and-the demand for dissipationxof heat by thecondenser is' greatly reduced; The restrictor will then return tov its normalposition for the refrigeration; operation in: whichit: imposes little or no resistance-to the how of the refrigerant returningtothecompressor;

In order toreducetheosuper heat of refrigerant gasreturning: to: the compressor after heat exchangewith thecondensing refrigerant, during the refrigeratingrcycle; theuppermwtpass 54 of the;condensererevaporizer isgprovided to, afford heats-exchange; by; convection; with, the; ambient ain=and1by conduction through; fins, M; The; re turning refrigerant is thus cooledl sufficiently prior to its entry into the compressor to insure efficient operation of the compressor.

The construction described is thus seen to serve in effect as a reversible heat exchange and cold storage means which reduces the load and increases the efficiency of operation during both the defrosting and refrigerating cycle. Moreover, the system automatically accommodates itself to the atmospheric conditions by reason of the fact that on those days and in those territories where the air has a high humidity causing rapid formation of frost on the evaporator coils, the condensation of moisture on the coils and fins of the condenser-revaporizer during the defrosting cycle will take place more rapidly and revaporizing of the refrigerant will be more effective.

The defrosting cycle may be continued as long as necessary to insure complete defrosting of the evaporator since the supply of moisture containing air relied upon for condensing moisture on the condenser-revaporizer is unlimited. In fact the defrosting cycle may be continued long after ice has been melted from the evaporator to cause heat to be supplied to air in any enclosure or conduit in which the evaporator is located. At such times the evaporator functions as a radiator and it may prevent over-cooling of an enclosure just as it operates to prevent overheating on the normal refrigerating cycle. Thermostatic or other suitable control of valve 24 will therefore convert the system into a complete temperature control or air conditioning unit having a great variety of applications.

The compact arrangement and effective heat interchange afforded by the condenser-revaporizer unit serves to reduce the cost of the entire assembly by permitting the use of a smaller condenser and revaporizer, and the nesting of one of these elements within the other. The cost of the installation is reduced and its efllciency of operation is increased, whereas the strains and loads on the system are minimized.

It should be understood, however, that the particular form, arrangement and construction of the elements employed in carrying out the present invention is capable of many variations particularly when adapting the invention to particular installations and refrigerating problems. view thereof it will be evident, that the invention is not limited to the particular construction shown in the drawing and herein described but that such embodiment has been chosen only for purposes of indicating the nature of the invention and illustrating a typical form thereof.

I claim:

1. A refrigerating system comprising a compressor, an evaporator, a condenser connected in series between said compressor and evaporator, a revaporizer connected in series between said evaporator and compressor, said condenser and revaporizer being combined into a single unit having a pair of headers located adjacent one end of the unit and another pair of headers located adjacent the opposite end of the unit, the condenser including tubes extending in parallel from a header adjacent one end of the unit to a header adjacent the opposite end of the unit, the revaporizer including tubes extending from the other header at one end of the unit to the other header at the other end of the unit, the tubes of the condenser and revaporizer being arranged directly in heat conducting relation with each other and means for circulating moisture containing air in heat exchanging relation with said condenser and revaporizer.

2. A refrigerating system comprising a compressor, and an evaporator, a condenser embodying a series of tubes connected in series between the compressor and the evaporator, a revaporizer comprising a series of tubes connected in series between the evaporator and the compressor, the tubes of said condenser and revaporizer being combined into a single unit wherein said tubes are arranged in parallel relation and directly in heat conducting relation with each other, bypass means for conducting refrigerant from the compressor to the evaporator so as to by-pass the condenser, means for controlling the flow of gas through said by-pass, a restrictor connected between the evaporator and revaporizer and located adjacent the revaporizer, and means for circulating moisture containing air over the tubes of said condenser and revaporizer.

3. A refrigerating system comprising a compressor, a condenser, an evaporator and a revaporizer connected together in series, said revaporizer and condenser embodying tubes arranged in direct heat conducting relation, bypass means for conducting refrigerant from the compressor to the evaporator so as to by-pass the condenser, means for controlling the fiow of gas through said by-pass, a restrictor connected between the evaporator and revaporizer and located adjacent the revaporizer, and means for circulating moisture containing air in heat exchanging relation with said condenser and revaporizer.

VICTOR W. SMITH.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,794,692 Hyde Mar. 3, 1931 2,323,511 Baker July 6, 1943 2,385,667 Webber Sept. 25, 1945 2,455,421 Kirkpatrick Dec. 7, 1948 2,526,379 Maseritz Oct. 17, 1950 FOREIGN PATENTS Number Country Date 59,500 Switzerland Jan. 20, 1912

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