US2902835A - Refrigeration defrosting system - Google Patents

Refrigeration defrosting system Download PDF

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US2902835A
US2902835A US533399A US53339955A US2902835A US 2902835 A US2902835 A US 2902835A US 533399 A US533399 A US 533399A US 53339955 A US53339955 A US 53339955A US 2902835 A US2902835 A US 2902835A
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heating
defrosting
fluid
coil
header
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US533399A
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John R Boyle
David H Gold
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Bohn Aluminum and Brass Corp
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    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25DREFRIGERATORS; COLD ROOMS; ICE-BOXES; COOLING OR FREEZING APPARATUS NOT COVERED BY ANY OTHER SUBCLASS
    • F25D21/00Defrosting; Preventing frosting; Removing condensed or defrost water
    • F25D21/06Removing frost
    • F25D21/12Removing frost by hot-fluid circulating system separate from the refrigerant system

Description

Sept. 8, 1959 J. R. BOYLE ETAL REFRIGERATION DEFROSTING SYSTEM Filed Sept 9, 1955 3 Sheets-Sheet l 4 INVENTORS. (john 123.30 16,

BY flay .Gold,

Sept. 8, 1959 J. R. BOYLE ETAL 2,902,835

" REFRIGERATION DEFROSTING SYSTEM Fi led Sept. 9, 1955 Y a Sheets-Sheet 2 L6 INVENTORS.

JUhW/JZ. 30 Le,- BY flmdflzd Sept. 8, 1959 J. R. BOYLE EIAL REFRIGERATION DEFROSTING SYSTEM Filed Sept. 9, 1955 5 Sheets-Sheet 3 INVENTORS. cjb7Z7'I/.R.B0 Ze BY flaz/zcifi bld 7 United States Patent 2,902,835 REFRIGERATION DEFROSTING SYSTEM John R. Boyle, Chicago, Ill., and David H. Gold, Hammond, Ind., assignors, by mesne assignments, to Bohn Aluminum & Brass Corporation, Detroit, Mich, a corporation of Michigan Application September 9, 1955, Serial N 0. 533,399

7 Claims. (CI. 62-45) This invention relates generally to defrosting systems and more particularly to an automatic defrosting system for removing the accumulation of frost on low temperature refrigeration coils.

Various types of defrosting systems have been proposed for refrigeration coils to automatically defrost the coils to remove ice therefrom so that the coils will operate efficiently. The refrigerating material used to cool the coils is sometimes heated for defrosting the same, and separate heating means such as electrical heaters are used in some cases to defrost the coils. However, these systems which have been available have not been entirely satisfactory especially for use with coils operating at very low temperatures. This is because a large amount of heat is required to remove ice which accumulates on the refrigeration coil. Accordingly, the coil must be heated for a long period of time and this may result in deterioration of the items normally kept cool by the refrigeration coil.

It is an object of the present invention to provide a defrosting system for low temperature coils which produces sufficient heat to defrost the coil in a short period of time.

Another object of the invention is to provide a defrosting system which provides the heat required for defrosting a low temperature coil in an efficient manner without producing excessive heat which might be applied to items cooled by the coil to damage the same.

A further object of the invention is to provide a defrosting system providing efficient defrosting of low temperature coils which is of simple and inexpensive construction and is entirely reliable in operation.

A feature of the invention is the provision of a defrosting system including defroster tubes in conducting engage- .ment with the refrigerating coil structure, with the de- :froster tubes and a heating chamber for heating fluid being provided as a sealed unit which is evacuated to the extent that a negative pressure exists therein so that the 'heated defrosting fluid initially moves rapidly through the coil. The fluid may be heated to a high temperature so that a large amount of heat is provided for rapid defrosting, and the pressure within the sealed defrosting system may rise to positive pressures.

Another feature of the invention is the provision of a sealed defrosting system for a refrigeration coil structure including a heating chamber for a vaporizable heating fluid, with a header extending vertically from the heating chamber and defroster tubes extending from the header, in which the header is of suflicient cross section to form a vapor dome for separating vapor from liquid, and includes a chamber extending above the uppermost defroster tube for receiving foreign non-condensable gases.

A further feature of the invention is the provision of a defrosting system wherein a vaporizable fluid is heated in a heating chamber, with heating tubes sealed in the chamber and heating units provided in the tubes to be completely sealed from the circulating system for the ice heating fluid so that the pressure in this system may be controlled as desired.

A still further feature of the invention is the provision of a defrosting system for a refrigerating coil wherein a vaporizable fluid is heated by electrical heating units and the entire structure is simple and compact with the electrical connections being sealed from moisture resulting from the defrosting action.

Further objects, features and the attending advantages of the invention will be apparent from a consideration of the following description when taken in connection with the accompanying drawings wherein:

Fig. 1 is an elevational view of a refrigerating coil structure including a circulating fan;

Fig. 2 is a cross section of the structure of Fig. 1;

Figs. 3, 4 and 5 show in detail the construction of the refrigeration coil structure andthe defrosting system in accordance with the invention;

Fig. 6 is a schematic diagram illustrating the operation of the defrosting system in accordance with the invention; and

Figs. 7, 8, 9 and 10 illustrate an embodiment of the defrosting system such as may be used for extremely large refrigerating coils.

In practicing the invention, a defrosting system is provided for a refrigeration coil structure which includes coil portions and fins secured thereto. The defrosting system includes a heating chamber with a header extending vertically therefrom and defroster tubes connected to the header and in contact with the fins of the refrigeration coil structure. The defrosting system is a sealed unit which has therein a heating fluid which may be a suitable tion coil and a heater such as an electric heater may beupright typesuch as might be used in a refrigerated cabi;

vaporizable liquid. The header has a cross section of such size to form a vapor dome which separates vapor from liquid so that the vapor rises and passes through the defroster tubes. The header has a chamber at the top for receiving foreign gases which may be present in the sealed unit. For heating the vaporizable liquid, heating tubes are sealed in the heating chamber in which heating units may be provided so that the heating units are completely isolated from the heating fluid in the chamber. Provision is also made for sealed electrical connections for the heating coils so that they are not affected by moisture produced by the refrigeration and defrosting action. The defrosting system is evacuated so that a negative pressure is provided therein when the heating fluid is not heated. Accordingly, as the fluid is heated, the vapor moves through the defrosting coils very rapidly to immediately start the defrosting action. Suflicient heat may be provided to raise the pressure in the sealed defrosting system to a positive pressure so that highly efficient heating of the refrigeration coil is provided and the defrosting may be very quickly accomplished. A control system may be provided which turns off the compressor for the refrigerating system and turns on the defrosting system. A drain pan may be required under the refrigeraprovided for the drain pan. In the event that a fan is provided for circulating air through the refrigerating coil, this fan may also be turned off during the defrosting cycle. A pressure limit valve may be provided in the defrosting system to prevent the refrigerant from being admitted into the refrigerating coil during the defrosting cycle to further expedite the defrosting action. The control of the various elements of the system may be provided by a timer so that the defrosting cycles occur at predetermined set times, and last for durations which are set to, take care of particular situations.

Referring now to the drawings, Figs. 1 and 2 illustrate a refrigeration unit which may be used in various types of refrigerated cabinets. This unit is of the mullion or net for bakery goods. A vertical housing 10 is provided having an intake opening 11 at the top through which air is drawn by a circulating fan 12. As shown in Fig. 2, the air drawn in by the fan is directed downwardly through the housing 10 across the refrigeration coil gen erally indicated as 13. The air is then dischargedat the bottom of the housing,,being directed in either or both directions through the openings 15 and/or 16. The coil unit 13 includes an intake coupling 17 for connection to thevoutput of a condenser, and an output coupling 26 for connection to a compressor of the refrigerating system.

In Figs. ,2, 3, 4 and the detailed construction of the refrigeration coil and of the defrosting system are shown. The refrigeration fluid comes. from inlet 17 through expansiorrvalve 18 to distributor 19 and then to the two separate lines 2% and 21 (Fig. 3). The refrigerant is applied through the coil structure including the longitudinal extending tubes 22 (Fig. 5), the front end bends 23 (Fig. 3)., and the rear end bends 24 (Fig. 2). As is apparent from Fig. 4, vertically positioned fins 25 are provided having therein openings for receiving the various longitudinal tube portions 22 of each vertical row. The refrigeration fluid, which has absorbed heat and is now a vapor, is discharged through return line 26. A bulb 27 connected to the expansion valve 18 is provided on the output coupling '26.

The defrosting system includes a heating chamber or boiler 28 to which is connected a header 29. Connected tothe header 29 are defroster tubes 30 which are terminated at the rear end of the unit by the duct structure 31. The rear duct structure includes a return section 32 which may extend under or around the refrigeration unit and is connected to the lower part of the heating chamber 28. The vapor is condensed in the defroster tubes 30 and returns by gravity through the duct structure 31 to the chamber '23. It is to be noted that one coil portion 30 extends in each vertical row of the longitudinal tubes of the refrigeration coil structure and is in heat conducting relation with the fins thereof. It is to be pointed out that in some systems the return duct structure may not be necessary as the condensed vapor may return through the header with the rising vapor.

The chamber 28 has a recessed front portion 33 from which extend tubes 34. These tubes are sealed to the end plates of the heating chamber so that the space in the heating chamber, the header, defroster tubes and rear duct structure may be hermetically sealed as a closed system. Heating units may be provided in the tubes 34 and a safety thermostat may also be provided in one of these tubes. The heating units and/or thermostat are connected to conductors provided with insulation suitable to withstand the moisture conditions encountered. The front end of the recess of the heating chamber 28 includes threaded lug portions 36 for connection of a cover plate 37 thereon so that a moisture proof enclosure is provided for the electrical connections. This is quite important since condensation and moisture from the de frosting of the refrigeration coils adversely affects the insulation on the conductors and causes deterioration thereof. By providing the conductors through the waterproof conduit 35 and sealing the recess portion 33 of the heating chamber the connections may all be protected from such moisture.

Considering now the construction and operation of the defrosting system, a vaporizable fluid is provided in the heating chamber 28. A fluid such as trichlorethylene in the pure state or Freon No. 113 may be suitable for such use. The amount of fluid used is not critical but is preferably such that it completely covers the tubes 34 in the heatingchamber 28 when the system is operating and some of the fluid is in liquid form. in the defroster tubes. The fluid mayxcompletely till. the heating chamber and extend. up into the header when the fluid is cold and there is no liquid fluid in the defroster tubes. The sealed dc expansion valve.

frosting system is then evacuated so that a negative pressure is provided in the sealed system. This may be accomplished by boiling the defrosting liquid and then evacuating air from the filler tube 40 at the top of the header 2.9. By way of illustration, the filler tube is shown having a valve 41 therein to permit the system tobe opened to provide the fluid therein, and for evacuating air therefrom.

It has been found that the system operates satisfactorilywhen a negative pressure is provided so that the absolute pr ssure within the system is of the order of 2 lbs. per square inch when using heating fluids as mentioned above. When the defrosting system is operated the heating units within the tube 34 are energized so that the fluid in the chamber 28 boils. Because of the negative pressure the vapor rises through the header 29 and then rapidly flows through the coil portions 30 into the return duct struc ture 31. As the heating continues, the pressure may build up within the system so that the system changes from a' vapor system to a positive pressure system. Pressures up to 15 lbs. per square inch, or an absolute pressure of 30 lbs. per square inch may be used. The use of such a wide pressure change results in correspondingly high temperature changes to thereby provide eflicient heating of the coil and rapid defrosting action. As an example, the coil may be operated at a temperature of minus 30 Fahrenheit and in such case the heater may heat the fluid to a temperature of around 200 Fahrenheit. This results in very fast defrosting of the refrigeration coils.

It will be apparent from Fig. 5 that the header 29 is of relatively large diameter. This is necessary so that the vapor from the boiling fluid rises and passes to the defroster tubes and the liquid fluid does not rise but remains in the heating chamber. tends substantially above the uppermost defroster tube 30. This provides a chamber into which non-condensible foreign gases and air which may accumulate in the system may rise during the defrosting cycle. Accordingly, any foreign gas in the system will have a minimum effect since it will not be in the circulating path during the defrosting operation. Although it is desirable that all air be removed from the system, this may not be entirely practical and the chamber at the top of the header renders this less critical.

It will be noted that the unit as shown in Figs. 3 and 5 includes a front top bracket 42 for mounting the coil structure in the housing 10. This bracket together with the housing forms a substantially enclosed chamber at the front end of the structure so that heat from the header 29 is effective to heat the return bends 23 of the refrigeration coil structure to defrost the same. This increased defrosting action at the return bends heats the refrigerant therein to speed up defrosting action. Similarly, at the rear of the unit the bracket 41 provided for supporting the unit from the housing provides a substantially closed chamber at the back so that the heated defrosting fluid in the return duct structure 31 heats the return bends 24 at the rear of the coil.

As shown in Fig. 2 a drip pan is provided at the bottom of the unit for receiving moisture resulting from the defrosting action. The drip pan has an outlet for discharging such moisture into a sewer or the like. Heating units may be provided in the drip pan so that the very cold water and ice resulting from the defrosting action is discharged through the outlet. Electrical heating units 45 may be provided for heating the drip pan 44.

Considering now the operation of the complete refrig-- eration and defrosting system, reference is made to Fig. 6. In this figure an electric motor 56 drives compressor 51 which provides compressed fluid to the condenser 52. The condensed refrigeration fluid is applied to a receiver 54 from which it is coupled through the inlet line-l7 to the A distributor may be provided for dividing the fluid into a. plurality of channels if this is desired. The refrigerating fluid flows through the refrig- The header 29 also ex-' pressed for repeated use. A fan 60 may beprovided for circulating air through the refrigeration coil 22so that the cooled air may be used as desired. The refrigerating coil structure and the defrosting system are the same as in Figs. 1 to 5 and the same reference characters are used.

In Fig. 6, the compressor is shown energized from a 230 volt line, with the connection being established through switch 61. The fan 60 is energized from a 115 volt line, with the connection being established through a switch 62. Switches 61 and 62 may be controlled by a timer 63 so that at a predetermined time or timm the refrigeration system is deactivated and the defrosting system is rendered active. The timer may first cause switch 61 to move to the upper position so that compressor motor 50 is stopped and the heaters in the heating chamber 28 are energized. The vaporized defrosting fluid will then rise in the header 29 and pass through the coils 30 in heat conducting relation with fins connected to the refrigeration coils. At the same time that switch 61 is operated, or at a somewhat later time, switch 62 will be operated to move to the upper position so that the fan 60 is stopped and the heaters 45 in the drip pan 44 are energized. As previously stated, this allows the defrosted moisture from the refrigerating coils to be held in a liquid stage so that it can be discharged from the drip pan. After a predetermined time, which has been determined to be adequate for removing the ice from the refrigeration coils, the switch 61 again is operated to the position as shown for energizing the compressor motor 50 and for deenergizing the heaters in the heating chamber 28. At a somewhat later time the switch 62 may be released so that the fan 60 is again operated and the drain pan heaters are de-energized.

The expansion valve 56 may be of a type which provides a shut-off when the pressure reaches a predetermined value. Accordingly, as the coil is heated and defrosted, the valve closes to prevent additional refrigeration fluid from flowing into the refrigeration coil. This speeds up the defrosting action since the additional fluid does not need to be warmed up. This valve may operate automatically so that after the defrosting action has started the valve will close. However, when the defrosting cycle is over and the heater for the defrosting fluid is turned off, the expansion valve will again open to allow the refrigeration fluid to pass therethrough and to expand and cool the refrigeration coil in the normal way.

InFigs. 7 to l0 there is illustrated a defrosting system which is suitable for use in larger refrigeration units. In such units the heating chamber must be quite large and cannot conveniently be provided at one end of the coil. Accordingly, a relatively long inclined heating chamber 65 is provided. A front header 66 is connected to the heating chamber 65, being generally similar to the header 29 of thefirst embodiment. This header has a cross section sufliciently large that liquid will not rise therein so that the vapor is effectively separated from the liquid. Coil portions 67 extend from the header to carry vapor from the heated fluid in chamber 65 to a rear header 68. Both the front and rear headers extend above the uppermost coil portion 67 to form a chamber in which foreign non-condensible gasses collect as described in the former embodiment. A return duct 69 connects the rear header 68 to the heating chamber 65.

The heating chamber 65 may have a recess 70 at the lower end thereof, with heating tubes 71 extending from the recess as in the prior construction. Electrical connections are made within the recess, with a conduit 72 providing a waterproof connection thereto. In the cmw re 6 bodiment of Figs. 7 to 10, a drip pan 73 may be provided under the coil having an outlet duct 74. This pan will be heated to a certain extent by the radiated heat from the heating chamber 65, and then further heated by a heating coil 75 provided on the bottom surface thereof.

The operation of the system of Figs. 7 to 10 is gen erally similar to that of the prior embodiment. Be cause of the size of the boiler, the boiler heaters may be turned off earlier and the defrosting will continue for a time from the heat built up therein. This will cause the heating to drop off gradually so that the load on the compressor will be less when the refrigeration unit is started up again. In small units such as in the prior embodiment it is not necessary to take these additional precautions.

The defrosting systems in accordance with the inven tion have been found to be highly satisfactory in applications in which they have been used. Since the systems start as vacuum systems, the heated vapor will circulate very fast so that the defrosting action will start immediately. By continuing the heating until a relatively high temperature is reached, ice built up on the refrigeration coils is removed very quickly. As stated above, since the unit is sealed, heating may be applied until a positive pressure is provided in the system. This provides a wide range operation and makes for very eflicient defrosting.

In representative systems the defrosting cycle will take place two or three times in each 24 hour day. These times can be set so that they interfere as little as possible with the operation of the unit. For example, when used in a store, the defrosting timer may be set sothat defrosting occurs when the store is closed and the refrigerator will not be opened. The duration of the defrosting cycle may generally be of the order of ten to twenty minutes depending upon the particular application. The number of cycles per day and the duration of the cycles can of course be adjusted by setting the timer so that best operation will be provided.

As a safety measure a thermostatic switch may be provided in the heating chamber to out off the system in the event that the heating chamber reaches a dangerously high temperature. This thermostat may be put in one of the sealed tubes in the heating chamber in the same manner as a heating unit. However, during normal operation the thermostatic switch would not operate since it is used only as a safety measure rather than to stop the defrosting cycle. Although it is believed desirable to start and stop the cycle by a. timer providing predetermined time intervals, it is also possible to use other controls which respond to the condition of the refrigeration coil structure.

Two embodiments of the invention have been illustrated which have been found desirable for units of two different sizes. Other configurations may be suitable for other applications incorporating the novel features set forth. The use of a sealed system operating at a negative pressure with a header providing a vapor dome effect produces rapid circulation of the heating vapor through the system, and by heating the heating fluid to a high tempera ture the defrosting action is quickly accomplished.

We claim:

1. A defrosting system for a refrigeration coil structure including in combination, a heating chamber for containing a heating fluid, a header extending upwardly from said chamber, elongated defroster tubes extending substantially horizontally from said header and extending through said refrigeration coil structure, and return duct structure connecting said defroster tubes at the ends. thereof remote from said header to said heating chamber; said heating chamber, said header, said defroster tubes and said return duct structure being interconnected as a hermetically sealed unit; vaporizable heating fluid in said sealed unit; heating means in said heating chamber for heating the fluid therein; said hermetically sealed unit.

7 being evacuated so that substantially only the vapor pres.- sure of the fluid remains therein when said heating units are de-energized, whereby the vapor resulting from the heated fluid produced upon energizing of said heating means flows rapidly through said defrosting coil; said header extending above the uppermost defroster tube to form a chamber for arresting any entrained foreign gas, entrapped in said sealed unit.

2. A defrosting system for a refrigeration coil structure including in combination, a heating chamber for containing a heating fluid, a header extending upwardly from said chamber, elongated defroster tubes extending substantially horizontally from said header and extending through said refrigeration coil structure, and return duct structure connecting said defroster tubes at the ends thereof remote from said header to said heating chamber; said heating chamber, said header, said defroster tubes and said return duct structure being interconnected as a hermetically sealed unit; vaporizable heating fluid in said sealed unit; heating means in said heating chamber for heating the fluid therein; said hermetically sealed unit being evacuated so that a negative pressure is provided therein when said heating means is de-energized, whereby the vapor resulting from heating of the vaporizable fluid rises in said header and flows rapidly through said defrosting coil; said header having a cross section of such size that a vapor dome is formed therein which separates the heating fluid in vapor form from the heating fluid in liquid form and the fluid in liquid form remains in said heating chamber.

3. A defrosting system for a refrigeration coil structure including in combination, a heating chamber for containing a heating fluid, a header extending upwardly from said chamber, elongated defroster tu-bes extending substantially horizontally from said header and in heat conducting relation with said refrigeration coil structure, and return duct structure connectingsaid defroster tubes at the ends thereof remote from said header to said heating chamber; said heating chamber, said header, said defroster tubes and said return duct structure being interconnected as a hermetically sealed unit; vaporizable heating fluid in said sealed unit; heating means in said heating chamber for heating the fluid therein; said hermetically seated unit being evacuated so that a negative pressure is provided therein when said heating means is de-energized, with operation of said heating units vapor-' izing said heating fluid and providing increased pressure in said sealed unit; said header having a cross section of such size that a vapor dome is formed and vapor resulting from heating of said vaporizable fluid rises in said header and flows through said defroster tubes with the fluid in liquid state remaining in said heating chamber.

4. A defrosting system for a refrigeration coil structure including in combination, a heating chamber for containing a vaporizable defrosting fluid, a header extending upwardly from said chamber, elongated defroster tube extending substantially horizontally from said header and extending through said refrigeration coil structure, and return duct structure connecting said defroster tubes at the ends thereof remote from said header to said heating chamber; said heating chamber, said header, said defroster tube and said return duct structure being interconnected as a hermetically sealed unit; vaporizable heating fluid in said sealed unit; a moisture-proof enclosure at one end of said chamber, heating tubes extending from said enclosure into said heating chamber, electrical heating units in said tubes for heating said fluid in said chamber, electrical connecting means in said enclosure for energizing said heating units to heat said chamber and said heating fluid; said hermetically sealed unit being evacuated so that a negative pressure is provided therein when said heating units are de-energized, whereby the vapor resulting from the heated fluid produced upon energizing of said heating means flows rapidly 8 through said defroster tubes; said header extending above the uppermost defroster tube to form a chamber for con taining foreign gases entrapped in said sealed unit.

5. A defrosting system for a refrigeration coil structure which includes a plurality of coil portions through which a refrigerant is circulated, said defrosting system including in combination, defroster tubes having portions in heating conducting relation with refrigeration coil structure, a heating chamber for containing a vaporizable heating fluid, said defroster tubes and said heating chamber being interconnected as a hermetically sealed unit, heating fluid in the sealed unit, sealed heating units in said heating chamber for heating said fluid in said chamber, control means including timing means for energizing said heating units to heat said chamber and said defrosting fluid therein, said hermetically sealed unit being evacuated so that a negative pressure is provided therein when said heating units are de-energized, whereby the vapor resulting from heated fluid produced upon energizing of said heating means flows rapidly through said defroster tubes, said control means causing said heating means to be energized for a sufficient length of time that the heating fluid expands and produces a positive pressure in said sealed unit to provide rapid heating of the refrigerating coil structure to defrost the same, and valve means for controllingflow of refrigerant through the refrigeration coil portions, said valve means including means responsive to the pressure of the refrigerant for stopping the flow of refrigerant when the pressure thereof reaches a predetermined value resulting from heating of the refrigerating coil structure.

67 A defrosting system for a refrigeration coil structure including in combination, a valve for controlling 'the flow of refrigerant in the coil structure, defroster tubes having portions in heat conducting relation with the refrigeration coil sttructure, a heating chamber for containing a heating fluid, said defroster tubes and said heating chamber being interconnected as a hermetically sealed unit, vaporizable heating fluid in the sealed unit, heating means extending into said heating chamber for heating said fluid therein, said hermetically sealed unit being evacuated so that a negative pressure is provided therein when said heating units are de-energized, whereby the vapor resulting from the heating fluid produced upon energizing of said heating means flows rapidly through said defrosting coil, said heating means when energized causing the heating fluid to be heated to an extent to provide rapid heating of the refrigeratingcoil structure to defrost the same, said valve including means responsive to the pressure of the refrigerant for stopping the flow of refrigerant through the refrigeration coil structure when the pressure of the refrigerant reaches a predetermined value resulting from the heating of the refrigerating coil structure.

7. A defrosting system for a refrigeration coil structure including in combination, a heating chamber for containing a heating fluid, a header extending upwardly from said chamber, elongated defroster tubes extending substantially horizontally from said header and extending through said refrigeration coil structure, said heating chamber, said header, and said defroster tubes being interconnected as a hermetically sealed unit; vaporizable heating fluid in said sealed unit, heating means in said heating chamber for heating the fluid therein, said hermetically sealed unit being evacuated and being substantially free of air and foreign gases and having a negative pressure therein when said heating means is deenergized, whereby the vapor resulting from heating of the vaporizable fluid rises in said header and flows rapidly through said defrosting coil; said header having a cross section of such size that a vapor dome is formed therein which separates the heating fluid in vapor form from the heating fluid in liquid form and the fluid in liquid form remains in said heating chamber, said header extending above the uppermost defroster tube to form a chamber for holding any entrained air or foreign gases out of the 2,181,276 Kogel et a1 Nov. 28, 1939 path of circulation of the vaporized heating fluid. 2,526,032 La Porte Oct. 17, 1950 2,551,163 Riekert et a1 May 1, 1951 References Cited in the file of this patent 2,553,657 La Porte May 22, 1951 5 2,652,697 Pellegrini Sept. 22, 1953 UNITED STATES PATENTS 2,081,479 Fink May 25, 1937

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1989008807A1 (en) * 1988-03-11 1989-09-21 Küba Kühlerfabrik Heinrich W. Schmitz Gmbh Process and device for defrosting the evaporator of a cooling unit
FR2678363A1 (en) * 1991-06-26 1992-12-31 Fourgeaud Monique Device for deep-freezing and preserving fresh products, in particular in baking and in pastry (cake) making
US5887440A (en) * 1996-09-13 1999-03-30 Dube; Serge Refrigeration coil defrost system

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Publication number Priority date Publication date Assignee Title
US2081479A (en) * 1932-04-18 1937-05-25 Kelvinator Corp Refrigerator defrosting method and apparatus
US2181276A (en) * 1936-04-16 1939-11-28 Servel Inc Refrigeration
US2526032A (en) * 1948-10-11 1950-10-17 Francis L La Porte Defrosting method and apparatus for refrigeration systems
US2551163A (en) * 1946-07-12 1951-05-01 Fred A Rickert Refrigerating apparatus
US2553657A (en) * 1947-03-06 1951-05-22 Francis L La Porte Refrigerator defrosting method and apparatus
US2652697A (en) * 1948-02-11 1953-09-22 Louis C Pellegrini Defrosting system for heat exchange devices

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2081479A (en) * 1932-04-18 1937-05-25 Kelvinator Corp Refrigerator defrosting method and apparatus
US2181276A (en) * 1936-04-16 1939-11-28 Servel Inc Refrigeration
US2551163A (en) * 1946-07-12 1951-05-01 Fred A Rickert Refrigerating apparatus
US2553657A (en) * 1947-03-06 1951-05-22 Francis L La Porte Refrigerator defrosting method and apparatus
US2652697A (en) * 1948-02-11 1953-09-22 Louis C Pellegrini Defrosting system for heat exchange devices
US2526032A (en) * 1948-10-11 1950-10-17 Francis L La Porte Defrosting method and apparatus for refrigeration systems

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1989008807A1 (en) * 1988-03-11 1989-09-21 Küba Kühlerfabrik Heinrich W. Schmitz Gmbh Process and device for defrosting the evaporator of a cooling unit
FR2678363A1 (en) * 1991-06-26 1992-12-31 Fourgeaud Monique Device for deep-freezing and preserving fresh products, in particular in baking and in pastry (cake) making
US5887440A (en) * 1996-09-13 1999-03-30 Dube; Serge Refrigeration coil defrost system

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