Limited subcooling condenser-receiver assembly for refrigerating systems

Dec. 8, 1970 p. h. dinger etal 3,545,228

LIMITED SUBCOOLING CONDENSER-RECEIVER ASSEMBLY FOR REFRIGERATING SYSTEMS

Filed Dec. 4, 1968

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United States Patent Office

3,545,228

Patented Dec. 8, 1970

545 228 LIMITED SUBCOOLING CONDENSER-RECEIVER ASSEMBLY FOR REFRIGERATING SYSTEMS Paul H. Dinger and Janies T. Stultz, Orlando, Fla., assignors to Ice Industries International, Inc., Longwood, Fla., a corporation of Florida

Filed Dec. 4, 1968, Ser. No. 781,046 Int. Cl. F25b 39/04

U.S. Cl. 62—506 4 Claims

ABSTRACT OF THE DISCLOSURE

A condenser-receiver assembly for ice-making refrigerating systems including an expansion valve and an evaporator, comprising a vertically disposed refrigerant conduit having an upper condensing region and a lower subcooling region therein, in combination with a cooling media conduit having vertically spaced coil portions located respectively in said upper and lower regions, the proximate ends of said portions being connected by a conduit length having a reduced heat exchange area as compared with the subcooling coil portion. The reduced heat exchange area in the space between the coil portions limits the temperature reduction in the subcooling region to the heat exchange potential of the subcooling coil portion.

This invention relates to a condenser-receiver assembly which limits the subcooled temperature of a refrigerant immediately following its condensation into liquid form, and more especially to an assembly of this type adapted for operation in ice-making refrigerating systems of the type disclosed in Pat. No. 3,146,610 and in our copending patent application Ser. No. 759,132.

In certain well-known types of condenser-receiver assemblies, a vertically disposed refrigerant container or conduit encloses a cooling media coil having uniformly spaced pitched turns from the top to the bottom thereof. The upper portion of the coil condenses the hot gaseous refrigerant vapor entering the top of the container and the resulting liquid accumulates in the lower portion of the container around the lower coil portion in heat exchange relationship. Thus, the temperature of the liquid refrigerant is further reduced by the lower coil portion to a point closely approaching the temperature of the cooling media flowing through the coil. This further temperature reduction is known in the trade as “subcooling” and it contributes to the efficiency of the refrigerating system.

In conventional hot gas defrost systems using an expansion valve or device, an evaporator and a condenserreceiver of the type described, however, a serious problem arises if the temperature of the cooling media in the coil should drop below approximately 40 degrees Fahren- -heit. In such an event, the low temperature of the liquid refrigerant surrounding the lower coil portion will, while subsequently flowing through the expansion device, cause the latter to decrease the flow to the evaporator. At this time, the continued condensation of gaseous refrigerant θθ entering the condenser-receiver, coupled with the reduced outflow of refrigerant, will produce an increased accumulation of the subcooled refrigerant in heat exchange relationship with the lower coil portion and a further reduction of temperature of the refrigerant. Since a rise in ₆₅the refrigerant level is accompanied by a corresponding increase in the heat exchange potential of the lower coil portion, a cumulative condition will persist in which the progressively accumulating liquid progressively lowers the subcooling temperature until the system ceases to function. 70

It is therefore an object of this invention to provide an improved condenser-receiver assembly which will over2 come the above-mentioned cumulative effect. Specifically, this object is attained by reducing or substantially eliminating the heat exchange area over a vertical distance separating the upper and lower coil portions of the coolg ing media conduit thereby limiting the subcooling temperature reduction to the heat exchange potential of the subcooling coil portion.

Some of the objects of invention having been stated, other objects will appear as the description proceeds IO when taken in connection with the accompanying drawings, in which:

FIG. 1 is a vertical sectional view through a condenser-receiver assembly according to our invention, and further showing schematically in association therewith the 15 complementary elements of an ice-making refrigeration apparatus;

FIG. 2 is a sectional plan view taken along line 2—2 in FIG. 1;

FIG. 3 is a top plan view taken along line 3—3 in FIG. 20 1; and

FIG. 4 is a vertical sectional view through an alternate form of condenser which may be substituted for the condenser shown in FIG. 1.

Referring more specifically to the drawings, the nu25 meral 10 denotes broadly an improved condenser-receiver combination according to the present invention and which is adapted to be operatively associated with the remaining elements of an ice-making refrigerating system 11 (FIG. 1). The system 11 may comprise motor-com30 pressor 12, expansion device or valve 13, hot gas valve 13α, heat exchanger 14, surge tank 15, and an evaporator 16.

The condenser-receiver 10 is connected to parts 12 through 16 in a manner more fully described in the afore35 mentioned patent. Briefly stated, high pressure discharge line 18 connects motor-compressor 12 to line 19; line 19, 19α connects valve 13α to the upper portion of condenser-receiver 10; line 20 connects the lower portion of the condenser-receiver to the lower portion of heat ex⁴⁰ changer 14; line 21 connects the upper portion of heat exchanger 14 to expansion valve 13; line 23 connects outlet 24 of evaporator 16 to surge tank 15; line 25 extends downwardly from the surge tank, through the heat exchanger, and to the suction side of motor-compressor 12; line 36 connects expansion valve 13 to evaporator 16; and line 19&amp; connects hot gas valve 13α to line 36.

The condenser-receiver combintion 10 comprises a refrigerant container or conduit 27 having a cooling media conduit therein, the latter conduit comprising a condenser coil portion 28 located in the upper interior region of container 27 and a subcooling coil portion 29 located in the lower interior region of the container. Coil portions 28 and 29 are vertically spaced apart and connected by a substantially straight conduit portion 30 having a reduced or relatively small heat exchange potential as compared with the associated coil portions 28 or 29.

The cooling media (usually water) from line 32 flows upwardly through coil portion 29, conduit length 30, coil portion 28 and then laterally through line 33, while the refrigerant flows downwardly from line 19, over coil portion 38, conduit length 30 and coil portion 29, and then laterally through line 20 to thereby effect counterflow cooling.

Since conduit length 30 represents a negligible amount of heat exchange area, the refrigerant level rise along htis length will not substantially lessen the subcooling temperature reduction effected by the submerged coil portion 29 and, hence, the temperature of the subcooled refrigerant will be stabilized. If desired, however, the conduit length may be located externally as hereinafter described with reference to FIG. 2.

3,545,228 ³ .

Operating conditions determine the minimum subcooling temperature desirable. Accordingly, the proper dimensions of the coil diameter, the height of coil portions 28 and 29, and the vertical space between the coil portions are selected as conditions require. In a typical construction, the height of portion 29 is approximately 3 inches with 8 helical turns, the height of straight conduit length 30 is approximately 7 inches, and the height of portion 28 is approximately 28 inches with 19 helical turns. The above dimensions relate to a shell or cylinder 27 about 4 inches in diameter and 40 inches long. Substantially the same proportionate corresponding dimensions may be selected for larger or smaller cylinders.

Concurrently with the flow of refrigerant during the freezing phase as described above, ice is formed in a well-known manner upon evaporator 16, after which the ice harvesting phase begins during which the ice is released from the evaporator. During the harvesting phase, hot gas valve 13n is open to permit the hot gasified refrigerant to flow from motor-compressor 12, through lines 18 and 19α, valve 13α, line 196, line 36, evaporator 16, line 23, surge tank 15, line 25, heat exchanger 14 and to motor-compressor 12.

The invention as described above functions as a condenser to condense the hot gasified refrigerant into liquid form while passing downwardly through the upper region of shell or conduit 27 and as a receiver and subcooler of hte liquefied refrigerant while passing through the lower region of this same shell or conduit, the condenser and subcooling coil portions 28 and 29 being vertically spaced apart a sufficient amount to prevent further subcooling of the refrigerant after heat exchange potential of coil 29 has been realized. Stated differently, the condensed liquefied refrigerant level in shell 27 ranges between coils 28 and 29 and longitudinally along connecting conduit portion 30 during the freezing phase and where the heat exchange capacity is negligible thereby preventing the heat exchange capacity of coil 28 from contributing to the subcooling capacity of coil 29.

FIG. 4 illustrates a slightly modified form of condenser 10α which may be substituted for the condenser 10 in FIG. 1 in the event the connecting length 30 in the latter figure should lessen the subcooling temperature reduction materially. It will be observed that the coil portions 28 and 29 in FIG. 4 are connected by upwardly extending conduit length 30α located externally of the cylinder 27, thereby completely eliminating the heat exchange area and subcooling effect of this length from the path of the refrigerant. A corresponding increase in efficiency will result.