US3766744A

US3766744A - Cube ice making machine and method

Info

Publication number: US3766744A
Application number: US00303037A
Authority: US
Inventors: W Morris
Original assignee: Individual
Current assignee: Individual
Priority date: 1972-11-02
Filing date: 1972-11-02
Publication date: 1973-10-23
Anticipated expiration: 1990-10-23
Also published as: CA975974A

Abstract

Automatic ice making apparatus for making cube ice, including a plurality of upright evaporators having opposite ice-forming surfaces defining plural cells for molding cube ice, water headers for discharging water downwardly onto the surfaces during the freezing cycle, and a compressor and condenser-receiver circuit including an auxiliary receiver circuit including an auxiliary receiver for supplying liquid refrigerant through an expansion valve to the evaporators during the freezing cycle. A conduit between the condenser-receiver and the auxiliary receiver is valved closed about a minute before the end of the freezing cycle to accumulate an overcharge of liquid refrigerant in the condenser-receiver to be converted to flash gas and transferred to the evaporators at the beginning of the harvesting cycle to aid defrost. Return of suction gas having enough wetness to absorb the heat out of the compressor walls during defrost is achieved, and make-up water to a sump is cooled by returning suction gas during the freezing cycle.

Description

United States Patent [1 1 Morris, Jr.

[ CUBE ICE MAKING MACHINE AND METHOD v [76] lnventor William F. Morris, Jr., Raleigh,

[22] Filed: Nov. 2, 1972 [21] Appl. No.: 303,037

Primary ExaminerWilliam E. Wayner Attorney-Thomas B. Van Poole et al.

[ Oct. 23, 1973 [57] ABSTRACT Automatic ice making apparatus for making cube ice, including a plurality of upright evaporators having opposite ice-forming surfaces defining plural cells for molding cube ice, water headers for discharging water downwardly onto the surfaces during the freezing cycle, and a compressor and condenser-receiver circuit including an auxiliary receiver circuit including an auxiliary receiver for supplying liquid refrigerant through an expansion valve'to the evaporators'during the freezing cycle. A conduit between the condenserreceiver and the auxiliary receiver'is valved closed about a minute before the end of the freezing cycle to accumulate an overcharge of liquid refrigerant in the condenser-receiver to be converted to flash gas and transferred to the evaporators at the beginning of the 28 Claims, 7 Drawing Figures minnow 2a m SHEET 16? 4 CUBE ICE MAKING MACHINE AND METHOD BACKGROUND AND OBJECTS OF THE INVENTION The present invention relates in general to ice making refrigeration systems, and more particularly to refrigeration systems for making cube ice wherein the system is cycled alternately through a freezing phase and a harvesting or defrosting phase.

Automatic ice making apparatus involving reversible cycle refrigeration systems have gone into wide commercial use. In such systems, ice is produced, usually in the form of an elongated tube or annular cylinder, during the normal refrigeration or freezing phase of the apparatus when-condensed liquid refrigerant is admitted to the evaporator, and the ice is discharged from the evaporator during the defrosting or harvesting phase when hot gaseous refrigerant is delivered directly from the compressor to the evaporator. Such systems have customarily involved an evaporator having a refrigerant chamber which contains a large volume of liquid refrigerant at the conclusion of the freezing cycle. To

accomplish proper defrosting and release of the ice from the evaporator by hot gaseous refrigerant and avoid an undesirable amount of melting of the ice as the hot gaseous refrigerant releases the frost bond between the ice and the evaporator ice-forming surfaces, it has been thought that some means must be provided to rapidly pump down the liquid which occupies evaporator at the end of the freezing cycle and transfer this liquid refrigerant to a cold transfer drum or storage tank at the commencement of the harvesting cycle to store the refrigerant during the remainder of the harvesting cycle. Also, it has been customary to employ a liquid trap to extract from the gas returning to the suction side of the compressor whatever liquid phase refrigerant is formed by condensation of hot gaseous refrigerant in the evaporator during the defrost cycle, to prevent any of the condensed liquid refrigerant from returning to the compressor. In such arrangements, only dry gaseous refrigerant is returned to the compressor during the harvesting cycle, which has poorer thermal transfer characteristics than wet gaseous refrigerant and is not capable of as-readily absorbing heat out of the compressor walls. Obviously the necessity of providing facilities for handling the liquid refrigerant when it is to' be dumped into a transfer drum for storage during the harvesting cycle, and the associated valving and plumbing, and the provision of such liquid traps in the suction line, increasesthe complexity and cost of the equipment as well as requiring relatively large quantities of refrigerant, and in'certain respects impairs defrost efficiency. I

Efforts have also been made to achieve effective and rapid harvesting of ice from the evaporator of automatic ice making apparatus by cycling hot gaseous refrigerant to the evaporator without dumping or storing the liquid refrigerant which remains in the evaporator at the conclusion of the freezing cycle. In such systems, the hot gaseous refrigerant is introduced into the refrigerant chamber of the evaporator in such a way that the hot gaseous refrigerant is placed in effective thermal exchange relation with the liquid refrigerant throughout the entire height of the body of liquid to quickly vaporize the liquid refrigerant or warm it sufficiently to release the frost bond holding the ice to the ice-forming surfaces of the evaporator. Such refrigeration systems have required a number of solenoid valves to effect proper selective control of intercoupling of the components of the refrigeration system to establish the various phases of operation forming the complete cycle of operation of the system and have not achieved the desired operating efficiency.

It has been discovered that by providing an additional auxiliary receiver connected to the usual water cooled condenser-receiver and closing the outlet from the condenser-receiver to the auxiliary receiver a short period before the conclusion of the freezing cycle, and connecting the hot gas line with the condenser-receiver and the evaporator sections in such a way that liquid refrigerant backed up in the condenser-receiver will vaporize as flash gas at the beginning of the defrost cycle, considerably improved efficiency of the defrost can be realized. With such an arrangement, sources of heat for releasing the ice from the ice-forming surfaces of the evaporator sections are provided by the flash gas from the condenser which vaporizes immediately upon opening of the hot gas solenoid valve to initiate the defrost cycle, as well as being provided by the hot gaseous refrigerant which is being delivered directly from the compressor high side; Also, by;providing a suction accumulator which'meters a proper small amount of liquid into the refrigerant returning to the compressor during defrost, the desired wetness of the returning suction gas can be achieved to absorb the heat from the walls or mass of the compressor totransmit it to the evaporator for adding further heat of defrost to the evaporator.

An object of the present invention is the provision of novel ice-making apparatus having a cycle of operation wherein the evaporator is cycled successivelythrough freezing and thawing phases with a novel mode of operation, whereby liquid refrigerant is accummulated in a water cooled condenser-receiver for a'short period before commencement of the harvesting cycle, to provide liquid refrigerant which will vaporize as flash gas and be fed to the evaporator to assist in defrost.

Another object of the present invention is the provision of novel automatic ice-making apparatus which is alternately cycled through freezing and harvesting phases, to produce cube ice with improved efficiency.

Other objects, advantages and capabilities. of the present invention will become ,apparent from the following detailed description, taken in conjunction with the accompanying drawings illustrating a preferred embodiment of the invention. 1 .BRIEF DESCRIPTION OF THE FIGURESv FIG. 1 is a diagrammatic view of automatic icemaking apparatus constructed'in accordance with the present invention; FIG. 2 is a side elevation view of the automatic ice making apparatus;

FIG. 3 is a vertical section view through tus, taken along the lines 3-3 of FIG. 2;

FIG. 4 is a horizontal section view through the ratus, taken along the line 4-4 of FIG. 3;

FIG. 5 is a fragmentary section view'"through the the apparaappaupper portion of the apparatus, taken along the line FIG. 7 is a fragmentary section view through the lower portion of one of the evaporator sections, taken along the line 7-7 of FIG. 6.

DETAILED DESCRIPTION OF A PREFERRED EMBQDIMENT Referring to the drawings, wherein like reference characters designate corresponding parts throughout the several figures, the basic components of the cube ice-making apparatus of the present invention are supported in an elongated, generally rectangular cabinet frame 10 of welded structural steel including a base frame portion 1 1,

upright end panels

12 and 13 and top frame members 14. The frame 10 also includes an upright intermediate partition 15 defining a compressor compartment between the partition 15 and the end panel 12 and an evaporator compartment between the partition 15 and end panel 13. In the compressor compartment region between the partition 15 and end panel 12 is a motor driven compressor 16 supported on a shelf 17 spaced above the base frame 11, the compressor having the usual high pressure discharge and low pressure suction ports. A high pressure discharge line 18 extends from the high pressure discharge port of the ompressor 16 through a conventional oil separator 19 and a supply conduit 20 to a Tee fitting 21. One branch of the Tee fitting 21 connects the hot gaseous refrigerant from the high side of the compressor through a conduit 22 and a manual discharge valve 23 to the inlet of the condenser-receiver 24.

The condenser-receiver 24 is of the usual water cooled type having water supply and

return pipes

25A and 25B and a valved by-passed pipe 25C, connecting the water pipes within the condenser-receiver 24 with the conventional exterior water tower. The outlet port of the condenser-receiver 24 is connected by liquid line 26 through a sight glass 27 and solenoid valve 28 to the inlet of an auxiliary receiver 29 having a capacity of about one-third the liquid capacity of the condenserreceiver 24. The outlet from the auxiliary receiver 29 is connected by liquid line 30 through a conventional liquid line dryer 31 and'sight glass 32 to the bottom inlet of the conventional coil in a knock-out tank or.

suctionaccumulator 33. The upper outlet of the spiral coil in the knock-out tank 33 is connected through liquid supply line 34 having a liquid solenoid valve 35 therein, to the expansion valve 36 and into the inlet of a liquid distributor 37. The liquid distributor 37 has plural outlet conduits 38 forming refrigerant distributor tubes of equal length having coiled portions to fit the longer tubes into confined spaces, with the distributor tubes extending over the tops of the evaporator sections 39 of evaporator unit 40 and down along side the back end walls of the evaporator sections 39 to the lower ends thereof.

Each of the evaporator sections 39, nine of which are provided in the example shown in the drawings, are each formed in one preferred embodimentwith two ice-forming

surfaces

41 and 42 of large area having vertically and horizontally extending metallic sheet mem bers defining many ice-forming cells or recesses 43 for producing ice cubes of about one inch size. For example, each of the ice-forming

surfaces

41 and 42 may be made up of a base plate 44, vertical divider partitions 45, and horizontally extending divider partitions 46 which, like the vertical dividers 45, are welded at their inner ends to the base plate 44 and at their edges to the vertical dividers 45 and incline outwardly and downwardly at an angle of about 15 to the horizontal. The base plate 44 forming each

surface

41, 42 is also sloped outwardly at a slight angle to the vertical, to facilitate migration of water discharged against the upper regions of the

surfaces

41 and 42 downwardly in contact with the

members

44, 45 and 46 defining the surfaces of the cells 43 without the water being thrown outwardly away from contact with these surfaces. The

members

44, 45 and 46 may be make of 16 gauge tinned copper in one satisfactory example.

Vertical copper pipes arranged parallel to each other and welded or brazed to the back surfaces of the base plates 44 in alignment with the junctures of the vertical dividers 45 with the base plate 44 extend substantially the full height of the ice-forming

surfaces

41, 42 and are formed, for example, of three-eighths inch copper tubes which are rolled or flattened to approximately a one-quarter inch depth measured perpendicularly to the surface of the base plate 44. These vertical copper tubes 47 open into and are joined to a transverse top manifold 48 at their upper ends and open into and join a bottom manifold 49 at their lower ends, both of which may be seven-eighth inch outer diametercopper tubes. Within the bottom manifold 49in coaxial relation is a smaller diameter liquid supply manifold 50, for example of three-eights inch outer diameter copper tube, having about three-sixteenth inch downwardly opening holes spaced about four and a half inches on centers along the liquid manifold 50. The liquid manifold 50 is closed at one end and is connected at the other end to one of the liquid distributor tubes 38. The larger diameter bottom manifold 49 is closed at both ends, one of the closed ends being apertured for passage of the smaller diameter of manifold pipe 50 therethrough, and is connected by a hole adjacent the latter end to one of a plurality of hot gas distributor tubes 51 extending upwardly along the back end wall of the associated evaporator section 39 and across the top thereof to a hot gas header 52. The hot gas header 52 communicates with the other branch of the Tee fitting 21 through a hot gas supply line 53 having a hot gas solenoid valve 54 and a strainer 55 therein. The top manifold pipes 48 associated with the tubes 47 of each of the ice-forming

surfaces

41 and 42 have one end thereof closed and the other end opens into an elongated suction header 56', which returns the vapor phase refrigerant from the evaporator sections through the coils of a forecooler 57, from which the gas is conveyed through line 58 to a gas inlet opening in the upper region of the cylindrical side wall of knock-out tank 33. The knock-out tank 33 includes the usual U tube, having an open end near the top of the tank into which the returning gas is drawn and conveyed through a conventional suction filter 59 and suction return lines 60 to the suction port of the compressor 16.

During the freezing cycle, water is dischargedv downwardly onto the upper portions of the ice-forming

surfaces

41, 42 by a plurality of spray nozzles or discharge tubes indicated at 61 spaced axially along each of a plurality of parallel horizontal water header pipes 62, a pair of which are associated with the upper ends of each of the evaporator sections 39. The transverse horizontal water header pipes 62 each connect to a common water supply pipe or header 63 which extends the length of the evaporator region of the cabinet frame and descends to connect to the outlet of a motor driven sump pump 64 located in an insulated sump or receptacle 65. The level of water in the sump 65 is monitored by a float valve 66 connected to a make up water supply pipe coupled to the city water supply or another desired water reservoir, the float valve when open admitting make up water through water supply conduits 67 to the forecooler 57 located for example in the upper region of the compressor compartment, from which a return line 68 descends to the sump 65. Also, an elongated trough 69 inclines upwardly from the sump 65 along the entire length of the zone occupied by the group of evaporator sections 39 in underlying relation to the evaporators to receive water which is discharged from the water header pipes 62 downwardly along the ice-forming

surfaces

41, 42 which does not freeze during transit along the ice-forming surfaces and return the water to the sump. A screen or perforated wall at the lower portion of the conveyor trough 69 permits the water to return to the sump but prevents ice from passing into the sump, and a screw conveyor 70 driven by an electric motor, for example through a chain and sprocket drive, is rotated during the discharge cycle to convey ice cubes or groups of ice cubes which are dislodged from the ice-forming surfaces of the evaporator sections during harvesting along the upwardly inclined path defined by the trough 69 for discharge through the outlet end 71 thereof to other conveyor means for transmitting the ice to other processing stages.

In the operation of the above described refrigeration system, at the beginning of the freezing cycle, the electric motor for the sump pump 64 is energized through suitable timer circuitry in the electrical panel box 72 to pump water from the sump 65 through sump pump 64 and water supply pipe 63 to the transverse water headers 62 and out the discharge nozzles or tubes 61, whereupon the water courses or migrates downwardly along the surfaces defining the cubic cells 43 of the

iceforming surfaces

41 and 42 of evaporator sections 39. The water which courses down these surfaces and which does not freeze into ice during its passage down the

surfaces

41, 42 discharges from the bottom of the evaporator sections 39 into the trough 69 whereit is returned to the sump 65 for recycling through the water circuit. At the same time the sump'pump 64 is placed in operation at the beginning of the freezing cycle, the hot gas solenoid valve 54 is closed and the liquid solenoid valve 35 is opened by automatic circuitry in the electric panel box 72. When this occurs, the hot gaseous refrigerant compressed in the compressor 16 is discharged from the high pressure port thereof through the discharge line 18, oil separator 19 and

conduits

20 and 22 to the condenser-receiver 24 where the hot gaseous refrigerant is condensed to liquidphase to form a seal of liquid refrigerantat the condenser outlet. The usual practice is'to' charge the system just enough to seal the condenser outlet with liquid refrigerant, but not drown the condenser. v

The condensed liquid refrigerant is supplied from the receiver 29 through the liquid line 30, knock-out tank 33, liquid line 34 and open liquid solenoid valve 35 to the expansion valve 36 which metersthe liquid refrigerant to the distributor 37 for distribution through the distributor tubes 38 to the liquid manifolds 50 supplying the liquid refrigerant to the vertical tubes 47 contacting the base plate 44 of the associated ice-forming

surfaces

41, 42 on opposite sides of each of the evaporator sections 39. The refrigerant at low pressure in the vertical tubes 47 of the evaporator sections 39 extracts heat from the ice-forming

surfaces

41, 42, freezing the water flowing'downwardly over these surfaces into ice in the cubic form defined by the surfaces of the iceforming cells or recesses 43'. As the refrigerant extracts heat from the ice-forming surfaces and the water, the refrigerant begins to return to vapor phase and is withdrawn from the evaporator tubes 47 through the top manifolds 48 to the suction header 56. From there, the cool vapor phase refrigerant courses through the coils in the forecooler 57 in thermal exchange with the make-up or city water being supplied to the forecooler when the float valve 66.is open, and is then conveyed through the line 58, knock-out tank 33 and suction filter 59 and return line 60 to the suction return port of the compressor 16.

When an appropriate thickness of ice has developed on the evaporator surfaces 41, 42 which may be determined by any of several known devices, such as by an automatic timer, or by an ice thickness sensor, or other conventional means, a harvesting or defrosting cycle is commenced. About 60 to 90 seconds before commencement of the defrost cycle, the solenoid valve 28 in the line between the condenser-receiver 24 and the auxiliary receiver 29 is closed to overcharge the condenser during this 60 to 90 second period and build up a reservoir of liquid refrigerant in the condenser for providing flash gas which will be transmitted to the evaporators immediately upon commencement'of the defrost cycle. The purpose of the auxiliary receiver 29 is to provide a reservoir of liquid refrigerant for this last sixty to ninety seconds of the refrigeration cycle when the valve 28 is closed, as otherwise'the liquid refrigerant supply to the evaporators would be exhausted in about ten seconds following closure of the valve 28. To initiate the actual defrost cycle, the hot gas solenoid valve 54 is opened and the liquid solenoid valve 35 is concurrently closed. The conditions thus established, and the heating effect of the cooling tower water flowing through the condenser tubes'connected to the

pipes

25A and 25B, which water is preferably at a tempera- IlJL Q Of about to promptly flashes the overcharge of liquid refrigerant in the condenser to produce a substantial volume of flash gas which is admitted throughlthe'hot gas solenoid valve 54-to the hot gas header- 52 and through the distributor tubes 51 and hot gas manifolds49 to the evaporator tubes 47 to immediately commence thawing of the frost bond holding the I ice cubes to the surfacesof the cells 43 on the evaporator surfaces 41, 42. During the initial phases of the harvesting cycle, the flash gas serves as the primary source of heat for defrosting, and thereafter. the heat of defrosting is supplied by the hot gaseous refrigerant which continues to circulate through the compressor from the suction returnv line 60 to the hot gas supply line 53 through valve 54 and thence to the hot gas header 52 and distributor tubes 51. Improved efficiency of defrost is contributed both by the development of the flash gas from the overcharge build-up in the condenser-receiver 24 and by the cycling of wet suction gas throughthe compressor and hot gas supply line 53 to the evaporator so as to absorb substantially all of the heat out of the walls or mass of the compressor body to contribute to the defrosting of the frost bond holding the ice on the evaporator surfaces. The proper wetness of the suction gas returning to the compressor is achieved by withdrawing the liquid which condenses during defrost in the evaporator tubes to the suction accumulator or knock-out tank 33 designed to accommodate this amount of liquid without slugging the compressor, and metering the proper amount of this liquid into the suction line 60 returning to the compressor 16 to achieve the desired wetness of the suction gas so that it will most effectively absorb the heat from the mass of the compressor casing. In this way the heat which has accumulated in the walls of the compressor casing while the compressor is working during the refrigeration cycle is then absorbed by thermal exchange into the gaseous refrigerant being delivered through the hot gas supply line 53 to the evaporators during the defrost cycle to obtain beneficial results from the heat stored in the compressor casing walls.

Thus, by the above described system, two basic sources of heat are drawn upon during the harvesting cycle to thaw the frost bond holding the ice to the iceforming surfaces: the heat provided by the flash gas formed from flashing the overcharge of the liquid refrigerant in the condenser at the beginning of the barvesting cycle; and the heat of the hot gaseous refrigerant being delivered from the compressor through the hot gas solenoid valve 54 and line 53 to the header 52,

the heat of the latter being enhanced by providing re-' turn suction gas to the compressor of proper wetness to absorb substantially all of the heat out of the walls of the compressor casing. In this manner, much more efficient defrosting is accomplished, facilitating the dislodgement of the ice cubes from the ice-forming surfaces of the evaporator so that the system can again return to the freezing cycle. In practice, the unit has a freezing cycle'of approximately 26 minutes and a defrost cycle of about 9 minutes. i

It should be recognized that three conditions are important to obtain substantial contribution to defrost from the flashing of the overcharge of liquid refrigerant in the condenser. There must be sufficient immersion of the water tubes in the overcharge of liquid refrigerant which is accumulated in the-condenser during the last 60 to 90 seconds of the freezing cycle; there must be a sufficient amount of overcharge of liquid refrigerant in the condenser at the beginning of the harvesting cycle to produce enough volume of flash gas; and there must be a substantial flow of approximately 80 to 85 condenser water circulated from the exterior cooling tower through the water tubes in the condenser and serving as the heat source. To provide the proper temperature of condenser water, it is desirable to provide a temperature control on the cooling tower to provide 80 water, for example by setting a fan control on the cooling tower or louvre controls associated ,with the cooling tower to maintain the cooling water at the desired temperature.

As the frost bond holding the ice cubes to the surfaces of the ice-forming cells, 43 on the evaporator surfaces is thawed sufficiently during the defrost cycle, the vertically elongated sheet of connected ice cubes which forms on each

evaporator surface

41, 42 detachs and falls gravitationally into the conveyor trough 69 where the sheet breaks into smaller fragments of plural ice cubes and individual ice cubes upon impact. To avoid bridging of such fragments as might form if the falling ice sheet struck the confronting evaporator surface, separator rods 73 hung from horizontal pivot axes adjacent the upper ends of the evaporator surfaces between confronting pairs of evaporator surfaces and depending downwardly to the level of the lower ends of the evaporator sections are provided to maintain the falling sheets in the proper path.

The fragments of plural ice cubes and individual ice cubes which are received in the conveyor trough 69 are then conveyed to the outlet end 71 by the screw con veyor 70, where they are transmitted either by another screw conveyor or by other collection or transfer means to further processing stages. For example, the ice can be passed to a cube separator device which separates the sheet fragments into individual cubes with minimal crushing of the cubes to thereby preserve as much as possible the cube form of the ice, and the ice can then be delivered to storage bins or to bag filling devices or other use stations.

What is claimed is:

1. The method of making and discharging ice with a refrigeration system including an evaporator, a condenser and a compressor by alternately cycling the systemthrough a freezing cycle and a harvesting defrost cycle, comprising the steps of coursing refrigerant from the compressor through the condenser to the evaporator for a selected freezing period during said freezing cycle to condense the refrigerant to form liquid phase refrigerant at the outlet end of the condenser and deliver it to the evaporator at a metered rate while concurrently discharging water over exterior ice-forming surfaces of the evaporator to form ice thereon, closing the outlet from the condenser to accumulate a selected overcharge of liquid refrigerant in said condenser for a short period before the end of the freezing cycle, and terminating delivery of liquid refrigerant to the evaporator to initiate the defrost cycle and concurrently connecting the condenser directly to the evaporator to rapidly convert said overcharge of liquid refrigerant to flash gas and transfer the flash gas to the evaporator to supply some of the heat for thawing the frost bond adhering ice to the ice-forming surfaces of the evaporator.

2. The method defined in claim 1, including discharging water downwardly onto said ice-forming surfaces continuously during the freezing cycle, collecting the water discharged onto said surfaces which does not freeze thereon and conveying it in a recirculating .path to redischarge it onto said surfaces, and terminating the discharge of water onto said ice-forming surfaces throughout the harvesting cycle.

3. The method defined in clairn.2, including passing make-up water from a supply source in thermal exchange relation with gaseous refrigerant returning from the evaporator to the compressor to cool the make-up water and comingle it with the recirculating water.

4. The method defined in claim 1, including. passing make-up water from a supply source in thermal exchange relation with gaseous refrigerant returning from the evaporator. to the compressor to cool the make-up. water, and comingling it with other water to be discharged onto said ice-forming surfaces of the evapora tor. 1

5. The method defined in claim 1, including circulating water at a temperature in the range of about -85F through'said condenser into thermal exchange relation with the overcharge of liquid refrigerant accumulated therein to prove a source of heat for rapidly vaporizing the overcharge refrigerant.

6. The method defined in claim 3, including circulating water at a temperature in the range of about 8085F through said condenser into thermal exchange relation with the overcharge of liquid refrigerant accumulated therein to prove a source of heat for rapidly vaporizing the overcharge refrigerant.

7. In ice making apparatus, a refrigeration system adapted to cycle alternately through a freezing cycle and a harvesting defrost cycle, including an enclosed evaporator chamber having an inlet and an outlet and including a generally upright, heat conducting wall defining an exterior ice-forming surface, water discharge means for directing water onto said ice-forming surface adjacent the top thereof during said freezingcycle to gravitate downwardly along the surface; a refrigerant circuit including a compressor, a condenser, a separate receiver, a liquid line section to the evaporator inlet having an expansion valve therein, and conduit means for coursing refrigerant from said compressor through said condenser and receiver in series circuit relation to said liquid line section to feed liquid refrigerant to the evaporator chamber during the freezing cycle; a branch conduit connecting the compressor discharge side and the inlet of the condenser with the evaporator inlet, valves in said branch conduit and in said liquid line section and between said condenser and receiver, and control means for closing the valve between the condenser and receiver a selected short time before the end of the freezing cycle to overcharge the condenser with liquid refrigerant and for concurrently closing the valve in said liquid line section and opening the valve in said branch conduit at the end of the freezing cycle whereupon the overcharge of liquid refrigerant in the condenser converts rapidly to flash gas and is delivered to the evaporator chamber to immediately assist thawing of frost bond adhering ice to said ice-forming surface.

8.- Ice making apparatus as defined in claim 7, wherein said condenser is a water cooled condenser, and means for circulating water at a temperature of at least about 80F through said condenser in thermal exchange relation with the overcharge of liquid refrigerant therein. v

9. Ice making apparatus as defined in claim 7, wherein said condenser is a condenser-receiver capable of storing liquid refrigerant therein, and said separate receiver is an auxiliary receiver having a liquid storage capacity about one-third that of the condenser-receiver to provide a reservoir of liquid refrigerant therein accumulated prior to said closing of the valve between the condenser and receiver to supply the expansion valve with adequate liquid refrigerant from said valve closing until termination of the freezing cycle.

10. Ice making apparatus as defined in claim 8, wherein said condenser is a condenser-receiver capable of storing liquid refrigerant therein, and said separate receiver is an auxiliary receiver having a liquid storage capacity about one-third that of the condenser-receiver to provide a reservoir of liquid refrigerant therein accumulated prior to said closing of the valve between the condenser and receiver to supply the expansion valve with adequate liquid refrigerant from said valve closing until termination of the freezing cycle.

11. Ice making apparatus as defined in claim 7, including a suction return line from said evaporator to said compressor having a suction accumulator therein for returning gaseous refrigerant of such wetness to the compressor during the defrost cycle as to absorb heat from the compressor walls causing cooling of the latter below ambient room temperature and transfer of the absorbed heat to the evaporator to aid in defrosting.

12. Ice making apparatus as defined in claim 9, including a suction return from said evaporator to said compressor having a suction accumulator therein for returning gaseous refrigerant of such wetness to the compressor during the defrost cycle as to absorb heat from the compressor walls causing cooling of the latter below ambient room temperature and transfer of the absorbed heat to the evaporator to aid in defrosting.

13. Ice making apparatus as defined in claim 10, including a suction return line from said evaporator to said compressor having a suction accumulator therein for returning gaseous refrigerant of such wetness to the compressor during the defrost cycle as to absorb heat from the compressor walls causing cooling of the latter below ambient room temperature and transfer of the absorbed heat to the evaporator to aid in defrosting.

' 14. Ice making apparatus as defined in claim 7, including a water recirculating system for collecting water discharging from said ice-forming surface below the bottom thereof and recirculating the collected water to the top of said surface for redischarge thereon, and means for supplying make-up water in thermal exchange relation with gaseous refrigerant returning from the evaporator to the compressor and comingling it with said recirculating water.

15. Ice making apparatus as defined in claim 9, including a water recirculating system for collecting water discharging from said ice-forming surface below the bottom thereof and recirculating the collected water to the top of said surface for redischarge thereon, and means for supplying make-up water in thermal exchange relation with gaseous refrigerant returning from the-evaporator to the compressor and comingling it with said recirculating water.

16. Ice making apparatus as defined in claim 11, including a water recirculating system for collecting water discharging from said ice-forming surface below the bottom thereof and recirculating the collected water to the top of said surface for redischarge thereon, and means for supplying make-up water. in thermal exchange relation with gaseous refrigerant returning from the evaporator to the compressor and comingling it with said recirculating water.

17; Ice making apparatus as defined in claim 7, wherein said ice-forming surface includes a vertically elongated base wall portion, the evaporator including vertically extending transversely spaced, parallel, metallic tubes joined to said base wall portion and spanning the height thereof, a horizontal top header pipe connected to each of said tubes at the upper ends thereof and communicating with the suction side of the compressor, an outer bottom header pipe connected to the lower ends of each of said tubes and communicating with branch conduit, and an inner bottom header pipe coaxially located within said outer bottom header pipe extending the axial length thereof communicating with said liquid line section downstream of the expansion valve and having plural orifices therein for feeding refrigerant into said outer bottom header pipe and into said tubes. I

18. Ice making apparatus as defined in claim 9, wherein said ice-forming surface includes a vertically elongated base wall portion, the evaporator including vertically extending transversely spaced, parallel, metallic tubes joined to said base wall portion and spanning the height thereof, a horizontal top header pipe connected to each of said tubes at the upper ends thereof and communicating with the suction side of the compressor, an outer bottom header pipe connected to the lower ends of each of said tubes and communicating with branch conduit, and an inner bottom header pipe coaxially located within said outer bottom header pipe extending the axial length thereof communicating with said liquid line section downstream of the expansion valve and having plural orifices therein for feeding refrigerant into said outer boom header pipe and into said tubes.

19. In cube ice making apparatus, a refrigeration system adapted to cycle alternately through a freezing cycle and a harvesting defrost cycle, including an enclosed evaporator chamber having an inlet and an outlet and including a generally upright, heat conducting wall defining an exterior ice-forming surface of large area having a plurality of recessed cells shaped to form ice cubes, water discharge means for directing water onto said ice-forming surface adjacent the top thereof during said freezing cycle; a refrigerant circuit including a compressor, a condenser-receiver, an auxiliary receiver, a liquid line section to the evaporator inlet having an expansion valve therein, and conduit means for coursing refrigerant from said compressor through said condenser-receiver and auxiliary receiver in series circuit relation to said liquid line section to feed liquid refrigerant to the evaporator chamber during the freezing cycle; a branch conduit connecting the compressor discharge side and the inlet of the condenser-receiver with the evaporator inlet, valves in said branch conduit and in said liquid line section and between said condenser-receiver and auxiliary receiver, and control means for closing the valve between the condenserreceiver and auxiliary receiver a selected short time before the end of the freezing cycle'to overcharge the condenser-receiver with liquid refrigerant and for concurrently closing the valve in said liquid line section and opening the valve in said branch conduit at the end of the freezing cycle whereupon the overcharge of liquid refrigerant in thecondenser-receiver converts rapidly to flash gas and is delivered to the evaporator chamber to immediately assist thawing of frost bond adhering ice to said ice-forming surface.

20. Ice making apparatus as defined in claim 19, wherein said condenser is a water cooled condenser, and means for circulating water at a temperature of at least about 80F through said condenser in thermal exchange relation with the overcharge of liquid refrigerant therein.

21. Ice making apparatus as defined in claim 19, wherein said condenser-receiver is capable of storing liquid refrigerant therein, and said auxiliary receiver has a liquid storage capacity about one-third that of the condenser-receiver to provide a reservoir of liquid refrigerant therein accumulated prior to said closing of the valve between the condenser-receiver and auxiliary receiver to supply the expansion valve with adeaute liquid refrigerant from said valve closing until termination of the freezing cycle.

22. Ice making apparatus as defined in claim 19, including a suction return from said evaporator to said compressor having a suction accumulator therein for returning gaseous refrigerant of such wetness to the compressor during the defrost cycle as to absorb heat from the compressor walls causing cooling of the latter below ambient room temperature and transfer of the absorbed heat to the evaporator to aid in defrosting.

23. Ice making apparatus as defined in claim 20, including a suction return line from said evaporator to said compressor having a suction accumulator therein for returning gaseous refrigerant of such wetness to the compressor during the defrost cycle as to absorb heat from the compressor walls causing cooling of the latter below ambient room temperature and transfer of the absorbed heat to the evaporator to aid in defrosting.

24. Ice making apparatus as defined in claim 21, including a suction return line from said evaporator to. said compressor having a suction accumulator therein for returning gaseous refrigerant of such wetness to the compressor during the defrost cycle as to absorb head from the compressor walls causing cooling of the latter below ambient room temperature and transfer of the absorbed heat to the evaporator to aid in defrosting.

25. Ice making apparatus as defined in claim 19, including a water recirculating system for collecting water discharging from said ice-forming surface below the bottom thereof and recirculating the collected water to the top of said surface for redischarge thereon, and means for supplying make-up water in thermal exchange relation with gaseous refrigerant returning from the evaporator to the compressor and comingling it with said recirculating water.

26. Ice making apparatus as defined in claim 19, wherein said ice-forming surface includes a vertically elongated base wall portion, the evaporator including vertically extendingtransversely spaced, paralle, metallic tubes joined to said base wall portion and spanning the height thereof, a horizontal top header pipe connected to each of said tubes at the upper ends thereof and communicating with the suction side of the compressor, an outer bottom header pipe connected to the lower ends of each of said tubes and communicating with branch conduit, and an inner bottom header pipe coaxially located within said outer bottom header pipe extending the axial length thereof communicating with said liquid line section downstream of the expansion valve and having plural orifices therein for feeding refrigerant into said outer bottom header pipe and into said tubes.

27. Ice making apparatus as defined in claim 21,

wherein said ice-forming surface includes a vertically elongated base wallportion, the evaporator including vertically extending, transversely spaced, parallel, metallic tubes joined to said base wall portion and spanning the height thereof, a horizontal top header pipe connected to each of said tubes at the upper ends thereof and communicating with the suction side of the compressor, an outer bottom header pipe connected to the lower ends of each of said tubes and communicating with branch conduit, and an inner bottom header pipe coaxially located within said outer bottom header pipe extending the axial length thereof communicating with said liquid line section downstream of the expansion valve and having plural orifices therein forfeeding refrigerant into said outer bottom header pipe and into said tubes. i

28. In cube ice making apparatus, a refrigeration system adapted to cycle alternately through a freezing cycle and a harvesting defrost cycle, including an enclosed evaporator chamber having an inlet and an outlet and including a generally upright, heat conducting wall defining an exterior ice-forming surface of large area having a plurality of recessed cells shaped to form ice cubes, water discharge means for directing water onto said cie-forming surface adjacent the top thereof during said freezing cycle; a refrigerant circuit including a compressor, condenser means for condensing refrigerant, a liquid line section to the evaporator inlet having an expansion valve therein, and conduit means for coursing refrigerant from said compressor through said condenser means to said liquid line section to feed liquid refrigerant to the evaporator chamber during the freezing cycle; a branch conduit connecting the compressor discharge side and the inlet of the condenser means with the evaporator inlet, valves in said branch conduit and in said liquid line section and controlling ing the valve in said liquid line section and opening the valve in said branch conduit at the end of the freezing cycle whereupon the overcharge of liqid refrigerant in the condenser means converts rapidly to flash gas and is delivered to the evaporator chamber to immediately assist thawing of frost bond adhering ice to said iceforming surface.

Claims

1. The method of making and discharging ice with a refrigeration system including an evaporator, a condenser and a compressor by alternately cycling the system through a freezing cycle and a harvesting defrost cycle, comprising the steps of coursing refrigerant from the compressor through the condenser to the evaporator for a selected freezing period during said freezing cycle to condense the refrigerant to form liquid phase refrigerant at the outlet end of the condenser and deliver it to the evaporator at a metered rate while concurrently discharging water over exterior ice-forming surfaces of the evaporator to form ice thereon, closing the outlet from the condenser to accumulate a selected overcharge of liquid refrigerant in said condenser for a short period before the end of the freezing cycle, and terminating delivery of liquid refrigerant to the evaporator to initiate the defrost cycle and concurrently connecting the condenser directly to the evaporator to rapidly convert said overcharge of liquid refrigerant to flash gas and transfer the flash gas to the evaporator to supply some of the heat for thawing the frost bond adhering ice to the ice-forming surfaces of the evaporator.

2. The method defined in claim 1, including discharging water downwardly onto said ice-forming surfaces continuously during the freezing cycle, collecting the water discharged onto said surfaCes which does not freeze thereon and conveying it in a recirculating path to redischarge it onto said surfaces, and terminating the discharge of water onto said ice-forming surfaces throughout the harvesting cycle.

3. The method defined in claim 2, including passing make-up water from a supply source in thermal exchange relation with gaseous refrigerant returning from the evaporator to the compressor to cool the make-up water and comingle it with the recirculating water.

4. The method defined in claim 1, including passing make-up water from a supply source in thermal exchange relation with gaseous refrigerant returning from the evaporator to the compressor to cool the make-up water, and comingling it with other water to be discharged onto said ice-forming surfaces of the evaporator.

5. The method defined in claim 1, including circulating water at a temperature in the range of about 80*14 85*F through said condenser into thermal exchange relation with the overcharge of liquid refrigerant accumulated therein to prove a source of heat for rapidly vaporizing the overcharge refrigerant.

6. The method defined in claim 3, including circulating water at a temperature in the range of about 80*-85*F through said condenser into thermal exchange relation with the overcharge of liquid refrigerant accumulated therein to prove a source of heat for rapidly vaporizing the overcharge refrigerant.

7. In ice making apparatus, a refrigeration system adapted to cycle alternately through a freezing cycle and a harvesting defrost cycle, including an enclosed evaporator chamber having an inlet and an outlet and including a generally upright, heat conducting wall defining an exterior ice-forming surface, water discharge means for directing water onto said ice-forming surface adjacent the top thereof during said freezing cycle to gravitate downwardly along the surface; a refrigerant circuit including a compressor, a condenser, a separate receiver, a liquid line section to the evaporator inlet having an expansion valve therein, and conduit means for coursing refrigerant from said compressor through said condenser and receiver in series circuit relation to said liquid line section to feed liquid refrigerant to the evaporator chamber during the freezing cycle; a branch conduit connecting the compressor discharge side and the inlet of the condenser with the evaporator inlet, valves in said branch conduit and in said liquid line section and between said condenser and receiver, and control means for closing the valve between the condenser and receiver a selected short time before the end of the freezing cycle to overcharge the condenser with liquid refrigerant and for concurrently closing the valve in said liquid line section and opening the valve in said branch conduit at the end of the freezing cycle whereupon the overcharge of liquid refrigerant in the condenser converts rapidly to flash gas and is delivered to the evaporator chamber to immediately assist thawing of frost bond adhering ice to said ice-forming surface.

8. Ice making apparatus as defined in claim 7, wherein said condenser is a water cooled condenser, and means for circulating water at a temperature of at least about 80*F through said condenser in thermal exchange relation with the overcharge of liquid refrigerant therein.

12. Ice making apparatus as defined in claim 9, including a suction return line from said evaporator to said compressor having a suction accumulator therein for returning gaseous refrigerant of such wetness to the compressor during the defrost cycle as to absorb heat from the compressor walls causing cooling of the latter below ambient room temperature and transfer of the absorbed heat to the evaporator to aid in defrosting.

14. Ice making apparatus as defined in claim 7, including a water recirculating system for collecting water discharging from said ice-forming surface below the bottom thereof and recirculating the collected water to the top of said surface for redischarge thereon, and means for supplying make-up water in thermal exchange relation with gaseous refrigerant returning from the evaporator to the compressor and comingling it with said recirculating water.

15. Ice making apparatus as defined in claim 9, including a water recirculating system for collecting water discharging from said ice-forming surface below the bottom thereof and recirculating the collected water to the top of said surface for redischarge thereon, and means for supplying make-up water in thermal exchange relation with gaseous refrigerant returning from the evaporator to the compressor and comingling it with said recirculating water.

16. Ice making apparatus as defined in claim 11, including a water recirculating system for collecting water discharging from said ice-forming surface below the bottom thereof and recirculating the collected water to the top of said surface for redischarge thereon, and means for supplying make-up water in thermal exchange relation with gaseous refrigerant returning from the evaporator to the compressor and comingling it with said recirculating water.

17. Ice making apparatus as defined in claim 7, wherein said ice-forming surface includes a vertically elongated base wall portion, the evaporator including vertically extending transversely spaced, parallel, metallic tubes joined to said base wall portion and spanning the height thereof, a horizontal top header pipe connected to each of said tubes at the upper ends thereof and communicating with the suction side of the compressor, an outer bottom header pipe connected to the lower ends of each of said tubes and communicating with branch conduit, and an inner bottom header pipe coaxially located within said outer bottom header pipe extending the axial length thereof communicating with said liquid line section downstream of the expansion valve and having plural orifices therein for feeding refrigerant into said outer bottom header pipe and into said tubes.

19. In cube ice making apparatus, a refrigeration system adapted to cycle alternately through a freezing cycle and a harvesting defrost cycle, including an enclosed evaporator chamber having an inlet and an outlet and including a generally upright, heat conducting wall defining an exterior ice-forming surface of large area having a plurality of recessed cells shaped to form ice cubes, water discharge means for directing water onto said ice-forming surface adjacent the top thereof during said freezing cycle; a refrigerant circuit including a compressor, a condenser-receiver, an auxiliary receiver, a liquid line section to the evaporator inlet having an expansion valve therein, and conduit means for coursing refrigerant from said compressor through said condenser-receiver and auxiliary receiver in series circuit relation to said liquid line section to feed liquid refrigerant to the evaporator chamber during the freezing cycle; a branch conduit connecting the compressor discharge side and the inlet of the condenser-receiver with the evaporator inlet, valves in said branch conduit and in said liquid line section and between said condenser-receiver and auxiliary receiver, and control means for closing the valve between the condenser-receiver and auxiliary receiver a selected short time before the end of the freezing cycle to overcharge the condenser-receiver with liquid refrigerant and for concurrently closing the valve in said liquid line section and opening the valve in said branch conduit at the end of the freezing cycle whereupon the overcharge of liquid refrigerant in the condenser-receiver converts rapidly to flash gas and is delivered to the evaporator chamber to immediately assist thawing of frost bond adhering ice to said ice-forming surface.

20. Ice making apparatus as defined in claim 19, wherein said condenser is a water cooled condenser, and means for circulating water at a temperature of at least about 80*F through said condenser in thermal exchange relation with the overcharge of liquid refrigerant therein.

24. Ice making apparatus as defined in claim 21, including a suction return line from said evaporator to said compressor having a suction accumulator therein for returning gaseous refrigerant of such wetness to the compressor during the defrost cycle as to absorb head from the compressor walls causing cooling of the latter below ambient room temperature and transfer of the absorbed heat to the evaporator to aid in defrosting.

26. Ice making apparatus as defined in claim 19, wherein said ice-forming surface includes a vertically elongated base wall portion, the evaporator including vertically extending transversely spaced, paralle, metallic tubes joined to said base wall portion and spanning the height thereof, a horizontal top header pipe connected to each of said tubes at the upper ends thereof and communicating with the suction side of the compressor, an outer bottom header pipe connected to the lower ends of each of said tubes and communicating with branch conduit, and an inner bottom header pipe coaxially located within said outer bottom header pipe extending the axial length thereof communicating with said liquid line section downstream of the expansion valve and having plural orifices therein for feeding refrigerant into said outer bottom header pipe and into said tubes.

27. Ice making apparatus as defined in claim 21, wherein said ice-forming surface includes a vertically elongated base wall portion, the evaporator including vertically extending, transversely spaced, parallel, metallic tubes joined to said base wall portion and spanning the height thereof, a horizontal top header pipe connected to each of said tubes at the upper ends thereof and communicating with the suction side of the compressor, an outer bottom header pipe connected to the lower ends of each of said tubes and communicating with branch conduit, and an inner bottom header pipe coaxially located within said outer bottom header pipe extending the axial length thereof communicating with said liquid line section downstream of the expansion valve and having plural orifices therein for feeding refrigerant into said outer bottom header pipe and into said tubes.

28. In cube ice making apparatus, a refrigeration system adapted to cycle alternately through a freezing cycle and a harvesting defrost cycle, including an enclosed evaporator chamber having an inlet and an outlet and including a generally upright, heat conducting wall defining an exterior ice-forming surface of large area having a plurality of recessed cells shaped to form ice cubes, water discharge means for directing water onto said cie-forming surface adjacent the top thereof during said freezing cycle; a refrigerant circuit including a compressor, condenser means for condensing refrigerant, a liquid line section to the evaporator inlet having an expansion valve therein, and conduit means for coursing refrigerant from said compressor through said condenser means to said liquid line section to feed liquid refrigerant to the evaporator chamber during the freezing cycle; a branch conduit connecting the compressor discharge side and the inlet of the condenser means with the evaporator inlet, valves in said branch conduit and in said liquid line section and controlling the outlet from said condenser means, and control means for closing the valve controlling the outlet from said condenser means a selected short time before the end of thE freezing cycle to overcharge the condenser means with liquid refrigerant and for concurrently closing the valve in said liquid line section and opening the valve in said branch conduit at the end of the freezing cycle whereupon the overcharge of liquid refrigerant in the condenser means converts rapidly to flash gas and is delivered to the evaporator chamber to immediately assist thawing of frost bond adhering ice to said ice-forming surface.