US 2637983 A
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y 12, 1953 H. MALKOFF ETAL 2,637,983
REFRIGERATING APPARATUS WITH HOT GAS DEFROSTING MEANS Filed Aug. 22, 1950 2 Sheets-Sheet 1 CDCD IN V EN TORS mom 5 V H. MALKOFF ET AL May 12, 1953 REFRIGERATING APPARATUS WITH HOT GAS DEF'ROSTING MEANS Filed Aug. 22, 1950 2 Sheets-Sheet 2 U U U U U U U U INVENTORS association with the other elements of the apparatus, and located therewithin by any suitable supports is an element I5 which is shown in the present instance as consisting of a coil of copper pipe filled with a heat holding substance such as a fusible salt of the proper crystalline form, for example, sodium sulphate (a satisfactory crystalline structure of sodium sulphate being ten molecules of Water to one molecule of sodium sulphate), lead acetate, ferric nitrate, or calcium chloride; the ends of the pipe coil I5 being closed. Such substances are well known as having low fusion points and their function in this apparatus is to serve as a constant source of held heat. Sodium sulphate, which we prefer for this purpose, has a fusion or melting point of about 93 F. and, when its temperature is reduced a single degree by transfer of heat the amount of heat transferred is equal to about 90 B. t. u. per pound of the salt. The other substances named are capable of fusing in a similar manner but have different fusion points.
One end of easing I4 has an orifice I6 formed therein through which passes the end of suction conduit 9 with a fluid tight fit, a suitable stuffing box (not shown) being provided for this purpose if necessary. The extremity of said conduit 5 is downwardly turned, as indicated at I1, in order to discharge the fluid passing therethrough into the lower part of casing I4. Another orifice I8 is formed in the said end of casing I4 for similarly accommodating a continuation I9 of the suction conduit 9 which leads to the inlet of the compressor I, as indicated at 20. The extremity of conduit I9 within the casing I4 extends substantially to the opposite end of the casing and is upwardly turned, as indicated at 2 I, so as to draw from the upper portion of the casing. It will be observed that a part of the suction conduit as it approaches the casing I4, which part is denoted by 22, lies alongside in contact, or at least in heat exchange relation with, a part of the hot gas compressor discharge conduit, which part is denoted by 23; whereby the said part 22 of the suction conduit, and the fluid passing therethrough, are heated by the part 23 of the hot gas line as the fluid flows from evaporator 4 to casing I4 so that the fluid may attain a temperature adequate to fuse the substance within coil I5.
A branch conduit 24 leads from the compressor hot gas refrigerant discharge conduit 5 to the drip pan coil 25 of the evaporator 4 and therefrom through another conduit 26 to conduit 8 at a point intermediate expansion valve 1 and the evaporator. In the said conduit 24 is positioned a solenoid valve 21 which is in electric connection with a source of current and a timing device (not shown but of any well known or approved form) for the purpose of periodically opening and closing the said valve. It will be clear that, when the valve 21 is opened, the hot gas from the compressor discharge will pass through conduits 24, 26 and 8 directly to the drip pan coil and evaporator coil of the evaporator 4, instead Of passing through the condenser 2, and that the said hot gas thus passing directly to the evaporator will serve to defrost the said coils thereof in a well understood manner.
In normal operation, the solenoid valve 21 is closed, and the refrigerant gas from the discharge of compressor I passes through conduit 5, condenser 2, in which it is liquefied, receiver 3, conduit 6, expansion valve 1, and conduit 8 into the evaporator 4 where it serves the purpose of chilling the refrigeration chamber in which the evaporator is located. This operation revaporizes the refrigerant and it flows through suction conduit 9 into casing I4 and from there through the portion I9 Of the suction conduit to the inlet 20 of compressor I. As this fluid flowing through the suction conduit from evaporator to compressor is in the form of gas or vapor, it will at once rise from the discharge I1 within the casing I4 to the intake 2| without being substantially affected by the heat holding substance in coil I5. However, if there is any liquid entrained with this gas, it will be vaporized by reason of the contact or juxtaposition of the part 22 of the suction conduit 9 with the part 23 of the hot gas discharge conduit as well as by the heat within casing I4 due to the presence therein of the heat holding substance.
When a defrosting period arrives, solenoid valve 21 will be opened by the automatic electric timer (not shown) and the hot refrigerant gas will then pass from the compressor discharge directly to the evaporator, as hereinabove described, for defrosting the latter. This defrosting step will liquefy the gas, at least in large part, so that the fluid returning through suction conduit 9 will be mainly, if not entirely, in liquid form. This liquid will, however, be revaporized in part by the heat exchange relationship of the portion 22 0f the suction conduit with the portion 23 of the hot gas conduit, but chiefly by heat transferred to the liquid refrigerant by the heat holding substance in coil I5. The liquid flowing from outlet I1 will drop to the bottom of the casing I4 where it will be vaporized by the coil I5, following which the vapor will rise and be drawn in through inlet 2| of portion I9 of the suction conduit and carried back to the inlet of the compressor. The heat content of the substance in coil I5 is maintained by the fact that, during normal refrigerating periods, the refrigerant vapor returning from the evaporator through suction conduit 9 passes in heat exchange relationship with a portion of the hot gas conduit from the compressor discharge and thus picks up sufficient heat which is imparted to the coil I5 when the gas is emitted from outlet I1.
It should be observed that, as will be clear to those familiar with this industry, the electric timer for controlling solenoid valve 21 may be set to become effective at any predetermined spacing of periods and for any predetermined duration; and that it will also be electrically connected with motor I3 so that the evaporator fan 12, which is in operation during refrigeration periods for circulating air, will be stopped during defrosting periods when solenoid valve 21 is opened. It may also be mentioned that a pipe 28 is connected with the drip pan of the evaporator 4 in order to drain off to a sewer or other disposal point the water received by the drip pan during defrosting, the said pipe 28 being in practice positioned close enough to pipe 24 to establish heat exchange relation and. prevent freezing.
Turning now to the modified form of the invention shown in Fig. 2, the compressor I, condenser 2, receiver 3, evaporator 4, conduit 6, expanion valve 1, conduit 8, suction conduit 9, feeler bulb I 0, capillary tube II, fan I2, motor I3, suction conduit portion I9, drip pan coil 25, conduit 26, solenoid valve 21, and drip pan pipe 28, are the same and function in the same way as the corresponding parts shown in Fig. 1 and hereinabove described.
The casing I4 and the heat holding coil are also substantially the same in construction as in tion conduit connecting the outlet of the evaporator with the inlet of the compressor for returning refrigerant from the former to the latter, a casing positioned in said suction conduit with the suction conduit entering the casing at a lower part thereof and leaving the casing at an upper part thereof, and a fusible heat holding substance positioned within said casing intermediate the points at which the suction conduit enters and leaves the casing, the parts being so constructed and arranged that the refrigerant flowing through the suction line surrounds the said heat holding substance in heat exchange relation therewith while passing through said casing from its point of entry to its point of leaving.
6. Refrigerating apparatus comprising, a compressor, a condenser, an evaporator, a conduit connecting the discharge of the compressor with the condenser and with the evaporator for conducting hot gas to the inlet of the condenser during refrigerating periods and to the inlet of the evaporator during defrosting periods, a suction conduit connecting the outlet of the evaporator with th inlet of the compressor for returning refrigerant from the former to the latter, a casing positioned in the said suction conduit, a portion of the hot gas conduit intermediate the compressor and the condenser being located within the casing, and a fusible heat holding substance also within said casing, the parts being so constructed and arranged that the refrigerant flowing through the suction line empties into the casing and surrounds the said heat holding substance and the said portion of the hot gas conduit as a fluid in heat exchange relation therewith while passing through said casing.
'7. Refrigerating apparatus comprising, a come pressor, a condenser, an evaporator, a conduit connecting the discharge of the compressor with the condenser and with the evaporator for conducting hot gas to the inlet of the condenser during refrigeratin periods and to the inlet of the evaporator during defrosting periods, a suction conduit connecting the outlet of the evaporator with the inlet of the compressor for returning refrigerant from the former to the latter, a casing positioned in the said suction conduit, a portion of the hot gas conduit intermediate the compressor and the condenser being in the form of a coil and located within the casing, and a fusible heat holding substance also within said casing contained in at least one hollow coil composed of heat conducting material intertwined with the coiled portion of the hot gas conduit, the parts being so constructed and arranged that the refrigerant flowing through the suction line surrounds the said heat holding substance in heat exchange relation therewith while passing through said casing.
OTTO J. NUSSBAUM.
References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 168,501 Jas Oct. 5, 1875 336,952 Schmitz Mar. 2, 1886 534,859 Cook et a1. Feb. 26, 1895 2,049,625 Ruppricht Aug. 4, 1936 2,440,146: Kramer Apr. 20, 1948 2,531,315 Wythe, Jr. Nov. 21, 1950