US 3499295 A
Beschreibung (OCR-Text kann Fehler enthalten)
-Nimh 10,' 1970 Filed June 17. 1968 J. H. BRENNAN REFRIGERATION SYSTEM 2 sneets-sheet z 48 EXPA Ns/o/v VALVE f f fxPANs/ON 50 l VALVE 1 f O XCONDENSEQ -D/Q/.E 1
X I@ 2 @ECE/V5@ JAMES H. RENNAN INVENTOQ Hor-neys United States Patent O 3,499,295 REFRIGERATION SYSTEM James H. Brennan, Trenton, NJ., assignor to Emhart Corporation, Bloomfield, Conn., a corporation of Connecticut Continuation-impart of application Ser. No. 693,200, Dec. 26, 1967. This application June 17, 1968, Ser. No.
Int. C1. Fzsb 41/00 U.S. Cl. 62-81 8 Claims ABSTRACT OF THE DISCLOSURE A refrigerating system embodying two evaporators which are alternatively operated on refrigerating and defrosting cycles, the liquid refrigerant being supplied to the evaporator that is operating on a refrigerating cycle being first passed through the other evaporator to defrost the same and reduce the temperature of the liquid refrigerant prior to expansion thereof in the evaporator undergoing refrigeration. When the temperature of the evaporator being defrosted has risen sufficiently to reduce its cooling action on the liquid refrigerant passing therethrough, the operation is reversed and the evaporator previously refrigerated is utilized to chill the liquid refrigerant passed to the previously defrosted evaporator for expansion therein in a refrigerating cycle.
RELATED APPLICATION This application is a continuation-in-part of copending application Ser. No. 693,200, filed Dec. 26, 1967.
BACKGROUND OF INVENTION As disclosed in said copending application it is frequently desirable to utilize two or more evaporators for refrigerating air circulated through or about a refrigerated iixture. It is further important in many instances to maintain the fixture and the refrigerated air supplied thereto at a substantially uniform temperature. At the same it is necessary to defrost the evaporators from time to time to remove frost and ice from the coils and fins thereof so as to assure continued and efficient refrigerating operation.
The defrosting of the coils and fins of evaporators has generally been effected heretofore by employing electrical heating elements or by circulating hot refrigerant gas directly from a compressor to the evaporator. Such systems frequently have required the use of elements which are relatively expensive to install and operate. Moreover, the defrosting means used usually serves to raise the temperature of the evaporator and/or the air in contact therewith far above that required to melt the ice and frost from the coils and fins of the evaporator. It is then necessary to dissipate such heat by the expenditure of additional refrigeration.
The liquid refrigerant supplied to the evaporators operating on the refrigerating -cycle in prior art systems has been supplied from a conventional condenser and receiver or it may be condensate received in whole or in part from the evaporator being defrosted by the circulation of hot refrigerant gas therethrough. However, in any such system the temperature of the liquid refrigerant supplied to the evaporator being refrigerated is generally in the neighborhood of 75 to 80 F. or more. As a result at least a portion of the latent heat absorbed upon vaporization of the refrigerant is expended in lowering the temperature of the liquid refrigerant entering the evaporator through the expansion valve.
In accordance with the present invention liquid refrigerant being passed to an evaporator operating on a refrigerating cycle is iirst passed through another evaporator 3,499,295 Patented Mar. 10, 1970 ICC operating on a defrosting cycle. In this way heat is extracted from the liquid refrigerant in melting the ice and frost on the coils and fins of the evaporator being defrosted. At the same time the temperature of the liquid refrigerant is lowered so that it is supplied to the refrigerating evaporator at a reduced temperature and the heat absorbing capacity and thermal efficiency of the refrigerating cycle is increased. Furthermore, since the evaporator being defrosted serves to supplement the action of the condenser used in the system, the size of the condenser required may be reduced. In a similar way the increased efficiency of the refrigerating cycle renders it possible to attain the desired refrigerating eifect by the vaporization of a lesser amount of liquid refrigerant whereby the size of the compressor employed may also be reduced. At the same time, neither evaporator used in the system need be heated to objectionably high temperatures during the defrosting thereof and the danger of adversely raising the temperature of air circulated over the evaporators and to the equipment being refrigerated is eliminated.
THE DRAWINGS FIGURE 1 is a diagrammatic illustration of equipment embodying the present invention, and
FIGURE 2 is a diagram showing a typical arrangement of elements employed in the practice of the present invention.
PREFERRED EMBODIMENTS OF THE INVENTION In that form of the invention chosen for purposes if illustration in the figures of the drawing, the system is employed for refrigerating an open self-service type of refrigerated fixture which may be of the type disclosed in said copending application Ser. No. 693,200. Such a fixture has an insulated enclosure indicated generally at 2, having an access opening 4 in the front wall thereof. The refrigerated space 6 within the case is refrigerated by circulating air alternately over one or the other of the two refrigerant evaporators 8 and 10 by means of a blower 12, or the like. The air is forced over that one of the evaporators 8 and 10 which is on the refrigerating cycle as exemplified by the evaporator 8 and is directed downwardly through a discharge opening 14 to form an air curtain 16 and may also be discharged into the refrigerated space 6. The air is drawn into a return inlet opening '18 at the lower portion of the case and is circulated through duct means 20 to the blower 12 for recirculation over the evaporator which is undergoing refrigeration.
The evaporators 8 and 10 are separated from each other by an insulating wall 26 so as to be located in adjacent compartments 22 and 24. Movable dampers or closures 28 are associated with the upper compartment 22 in which the evaporator coil 8 is located, whereas similar dampers or closure members 30 are associated with the lower compartment 24 in which the evaporator coil 10 is located. As shown, the evaporator coil 8 may be considered to be operating on a refrigerating cycle, whereas the lower coil 10 is operating on a defrosting cycle. At such times, the dampers 28 associated with the compartment 22 will be opened as shown to allow air from the blower 12 to flow over the coils and fins of the evaporator 8 and through the plenum chamber 32 to the discharge opening 14. At .the same time, the dampers 30 associated with the compartment 24 will be closed to prevent air from circulating over the evaporator 10 and through said compartment while the evaporator 10 is being defrosted. As a result the relatively warm or unrefrigerated air adjacent the evaporator 10 will not be permitted to mingle with the refrigerated air passing through compartment 22 and over the evaporator 8 to raise the temperature of the air supplied to the fixture being refrigerated.
The equipment may be operated in this manner until the evaporator '8 has been coated with ice and frost. Thereafter, when it is desired to defrost the evaporator 8, the dampers 28 will be closed and the dampers 30 will be opened and evaporator 10 will be operated on a Arefrigerating cycle while the evaporator 8 is being defrosted. In this way, it is possible to assure a continuous flow of refrigerated air to the discharge opening 114 for establishing the air curtain 16 in front of the access opening 4 and for circulating refrigerated air through and about the refrigerated space 6 within the case to refrigerate the space 6 and the articles therein.
The equipment shown in FIGURE 1 is preferably operated by means of the refrigerating system illustrated diagrammatically in FIGURE 2. As there shown, the refrigerating means embodies a compressor 34, a condenser 36, a receiver 38 and a dryer 40. Since the evaporator 8 is operating on a refrigerating cycle the refrigerant compressed by the compressor 34 is passed to the condenser 36 and receiver 38 and then passes to the dryer 40 from which the liquid refrigerant ows through a supply line 42 to a two-way valve 44. As indicated by the arrows in FIGURE 2, the valve 44 is adjusted initially to cause the liquid refrigerant to flow through the conduit '46 to the coils of evaporator 10. The temperature of such liquid refrigerant will then be above 32 F. or about room temperature, say 70 to 80 F. At the same time the temperature of the frost or ice coated coils and fins of evaporator 10 will be no more than 32 F. and may at a temperature of F. or less. The liquid refrigerant from the conduit 46, upon entering the coils of evaporator 10, will therefore be cooled by the coils and fins whereas the temperature of the coils and fins will be raised suiciently to melt the ice and frost thereon so as to effectively defrost the evaporator 10. The cooled liquid refrigerant issuing from the evaporator will then have a temperature of about 30 F. to 40 F. and flows through the outlet duct 48 and by-pass line 50 t0 a diverting valve 52. In this way, the cooled liquid refrigerant is supplied to the expansion valve 54 associated with the evaporator 8. The cooled liquid refrigerant is vaporized within the evaporator 8 and since it has previously been reduced in temperature by its passage through the evaporator 10, the temperature of the liquid refrigerant entering the expansion valve 54 will be substantially reduced and will be in the neighborhood of 30 or 40 F. The heat absorption capacity of the refrigerant is thereby increased so that upon expansion within the coils of evaporator 8 the temperature of the coils and fins of evaporator 8 will be reduced substantially below that which the coils and tins would attain if the liquid refrigerant supplied to the expansion valve -54 had been at room temperature or say 75 to 80 F. as is conventional practice. Accordingly, a lesser amount of expanding refrigerant is required in order to attain a desired low temperature and the amount of vaporized refrigerant returning to the compressor is reduced. Therefore, the compressor employed may be reduced in size and capacity below that which would otherwise be needed.
The vaporized refrigerant gas leaving the evaporator 8 returns to the compressor` 34 through the line 56, valve 62 and return line 64 for recompressing and cooling in condenser 36. 'Ihe equipment may be operated as described above until the coils and fins of evaporator I10 have been defrosted and no longer serve to effectively cool the liquid refrigerant being supplied to the evaporator 8. The operation is then reversed and the evaporator 8 will be operated on a defrosting cycle, while evaporator |10 is operated on la refrigerating cycle. Such reversal is effected by operation of the two-way valves 44 and 62 and diverting valve 52 to cause liquid refrigerant from the receiver 38 and dryer 40 to flow through the conduit 42 and Valve 44 to the line 56 Which serves to supply the uncooled liquid refrigerant to the coils and fins :of the evaporator 8. The liquid refrigerant circulated through the coils of evaporator 8 then serves to defrost the coils and fins and to reduce the temperature of the liquid refrigerant which issues from the evaporator 8. The resulting chilled liquid refrigerant flows through the line 66 which by-passes the expansion valve 54. The liquid refrigerant then flows through the diverting valve 52 which has now been adjusted to cause the liquid refrigerant to flow through the line 56 and expansion valve 58 to the coil of the evaporator 10. The cooled liquid refrigerant then is expanded within the coils of the evaporator 10 and returns through the line 46 and valve 62 to line 64 and the compressor 34. Accordingly, the evaporator 8 will be defrosted, Whereas the evaporator 10 will be refrigerated.
Further, during such reversed operation of the equipment, the dampers 28 associated with the evaporator 8 will be closed and the dampers 30 associated with the evaporator 10 will be open, whereby the air circulated by the blower 12 will ow through the lower compartment 24 and over the coils and fins of the refrigerating evaporator 10 to the discharge opening `14. Since the damper 28 associated with the compartment 22 and the evaporator 8 will be closed at this time it will prevent the ow of air over the defrosting evaporator 8 to mingle with the refrigerated air flowing over the refrigerating evaporator 10 and through the lower compartment 24. As a result, the operation of defrosting the evaporator 8 does not tend to raise or vary the temperature of the air circulated through the discharge opening 14 and through or about the storage space 6 within the fixture.
The operati-on of the dampers 28 and 30 and valves 44, 52 and 62, for effecting a reversal of the direction of flow of the refrigerant in the system, can be accomplished under the control of suitable means responsive to the temperature of the liquid refrigerant leaving the coil being defrosted and iiowing to the coil being refrigerated. For this purpose thermostats 70 and 72 may be located in contact with the by-pass lines 5() and 66 or elsewhere to cause solenoids 74, 76 or the like to be actuated to control valves 44, 52 and 62. Further, the operation of the closures or dampers 28 and 30` which control the ow of '-air through the compartments 22 and 24 may be effected /by electrical means such as the solenoids 74, 76 or otherlwise to coincide with the operation of the valves 44, 52 and 62 by means of which the cycle is reversed. Such solenoids may obviously be connected into a single electrical circuit for simultaneous operation, if desired, assuring the proper and desired operation of the valves and dampers to control the functioning of the system.
While the present invention has been described with particular reference to its application to refrigerated equipment such as that shown and described in copending application Ser. No. 693,200, it will be apparent that the system may be used with other types of refrigerated fixtures or equipment. Furthermore, it will be apparent that any number of evaporators may be used in combination and the invention may be employed in controlling the refrigeration of a plurality of refrigerated devices located in different areas if desired.
For the foregoing reasons it will be apparent that numerous modifications and applications of the present invention are permissible in the practice of the present invention.
1. The method of defrosting the coils and fins of evaporators which are operated alternatively and successively on refrigerating and defrosting cycles which comprises the steps of passing liquid refrigerant' at a temperature about 32 F. from a source thereof through a first evaporator which is operating on a defrosting cycle without expansion of the refrigerant to thereby raise the temperature of the coils and tins of the first evaporator suficiently to melt any ice and frost thereon and simultaneously lower the temperature of the liquid refrigerant, passing the liquid refrigerant which has thus been cooled by passage through the first evaporator into a second evaporator which is operating on a refrigerating cycle,
vaporizing the cooled liquid refrigerant in said second evaporator to refrigerate the same, and thereafter reversing the direction of flow of refrigerant from said source through said first and second evaporators to defrost the second evaporator and operate the first evaporator on a refrigerating cycle.
2,. The method as defined in claim 1 wherein the reversal in direction of fiow of the refrigerant between said evaporators is effected in response to a rise in ternperature of the liquid refrigerant leaving the evaporator being defrosted.
3. The method of refrigerating a fixture to which refrigerated air is supplied from a first and a second evaporator which comprises the steps of passing liquid refrigerant at a temperature above 32 F. from a source thereof through the first of said evaporators without expansion of the refrigerant therein whereby said rst evaporator will be defrosted and the temperature of the liquid refrigerant reduced, thereafter passing the liquid refrigerant which has thus been cooled to the second evaporator, vaporizing the cooled liquid refrigerant in the second evaporator to reduce the temperature of the second evaporator, circulating air over the second evaporator to said fixture until the temperature of the liquid refrigerant passing to the second evaporator rises, then reversing the direction of flow of the refrigerant from said source through said evaporators to defrost the second evaporators and vaporize cooled liquid refrigerant in the first evaporator, and simultaneously discontinuing the circulation of air from the second evaporator to the fixture and initiating the circulation of air over the first evaporator to the fixture.
4. A refrigerating system comprising a source of liquid refrigerant, a first and a second evaporator, means for supplying liquid refrigerant at a temperature above 32 F. from said source to the first of said evaporators without vaporization of the refrigerant therein, means for supplying liquid which has passed through the first evaporator to the second evaporator for evaporation in the second evaporator, and means for reversing the direction of flow of refrigerant through said evaporators to defrost the second evaporator and vaporize refrigerant in the first evaporator.
5. A refrigerating system as defined in claim 4 wherein means responsive to a rise in temperature of the liquid refrigerant are utilized to control the reversal in direction of fiow of the refrigerant through the evaporators.
6. In combination with a fixture to be refrigerated a source of liquid refrigerant, a first evaporator, a second evaporator, means for passing liquid refrigerant at a temperature above 32 F, from said source to said first evaporator without vaporizing the refrigerant therein, means for supplying liquid refrigerant from said first evaporator to said second evaporator, means for effecting the vaporization of said refrigerant in said second evaporator, means for periodically reversing the direction of fiow of refrigerant from Said source through said evaporators to defrost one evaporator while the other evaporator is undergoing refrigeration, and means for passing air over the evaporator being refrigerated to said fixture.
7. A combination as defined in claim 6 wherein said first and second evaporators are located in separate compartments, closure members are provided for each compartment and means are provided for opening the closure members associated with the compartment in which the evaporator being refrigerated is located to permit the ow of refrigerated air to the refrigerated compartment to said fixture and to simultaneously close the closure means associated with the compartment in which the evaporator being defrosted is located.
8. The combination as defined in claim 7 wherein the reversal in direction of flow of the refrigerant between the evaporators and the opening and closing of said closure members are controlled by means responsive to a rise in temperature of the liquid refrigerant.
References Cited UNITED STATES PATENTS 1,859,427 5/1932 Bulkeley 62-278 2,960,840 11/ 1960 Hosken 62-278 FOREIGN PATENTS 12,896 6/ 1891 Great Britain.
WILLIAM I. WYE, Primary Examiner U.S. Cl. X.R` 62-156, 256, 278
Patent No. 3, 499, 295
Dated Inventor(s) James H. Brennan (SEAL) mma if. um Jr. .Atsdng Officer It is certified that error appears in the aboveand that said Letters Patent are hereby corrected as UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION March 10, 1970 identified patent shown below:
should be changed to Hmm E. SGHUYLER, JR. Gomissioner of Patents USCOMM'DC 503764359 l ILS. GDVERNMENY PRINTING OFFICE: Il. 0-366-334