US2181276A - Refrigeration - Google Patents

Description

.Nov'.2s,1939. v K EL Em 2,181,276

REFRIGERATI ON Filed April 12, 1937 3 Sheets-Sheet l mvrswrozgs Nov. 28. 1 w. G. KOGEL- ET AL REFRIGERATION Filed April 12, 1937 s Sheets-Sheet 2 INVENTORS mm" by W @WL WATTORNEY.

NOV. 28, 1939. w Cj 2.181,Z76

REFRIGERATION Filed April 12, 1937 3 Sheets-Sheet 5 39 I 2 Q @I m F j v i I 50 5/ a 'II a? a o I x 75 r a 7b 7 -36 Ill 75 Q E 5/ a0 i I I i .75- L INVENTOBS BY I (P mam ATTQRNEY.

Patented Nov. 28, 1939 UNITED STATES 2,181,276- REFRIGERATIQN Wilhelm Georg Kiigel, Paul strandbergrand Gunnar Grubb, Stockholm, Swedem'assignorsDby mesne assignments, to Servel, Inc New York,

N. Y., a corporation of Delaware Application April 12, 1932; 'Sei'ia'l'No. 136,274

In Germany April 16, 1936 25 Claims. This inventionrelates to refrigeration, and

more particularly to defrosting of a cooling ele-v refrigeration system to effect defrosting is avoided.

Another object of the invention is to utilize heat from a part of a refrigeration system toheat a cooling element thereof to cause rapid melting of frost accumulated on the cooling element.

A furtherobject of the invention is to heat a cooling element to cause melting of frost, and to terminate such heating automatically when the cooling element is substantially defrosted.

A still further object of the invention is to provide a heating system for heating a cooling element which, in addition to defrosting the\cooling element, may be effectively utilized to heat an enclosed space in which the cooling element is arranged, so that the enclosed space can be maintained substantially at a desired temperature.

The above and other objects and advantages of the invention will be more fully understood from the following description taken in connection with the accompanying drawings forming a part of this specification, and of which Fig. 1 diagrammatically illustratesa refrigeration system provided with defrosting apparatus embodying the in Fig. 1; Fig. 3 is a fragmentary sectional view illustrating a modification of the apparatus shown in Fig. 1 whereby, in addition to heating the cooling element, the storage space in which 'it is arranged may be heated to maintain the latter substantially at a desired temperature; Fig. 4 is a view in elevation of the apparatus shown in Fig. 3; Fig. 5 ma fragmentary sectional view illustrating a further modificationof the apparatus shown in Fig. 1; Fig. 6 is a sectional view on line 6-5 of Fig. 5; and Figs. 7 and 8 are'fragmentary views of the apparatus shown in Fig. 5 to illustrate more clearly parts of the apparatus.

Referring to Fig. 1, the invention is shown in connection with a refrigeration system of a uniform pressure absorption type, generally as described in Patent No. 1,609,334 to von Platen and Munters, in which an auxiliary pressure equalizing gas is employed. It is to be understood, however, that the invention can 'be employed with other types of refrigeration systems.

The system includes a cooling element or evap- Agdl. 62-5) orator l0 disposed in an enclosed space H which may form a food storage compartment of a thermally insulated refrigerator cabinet l2. The refrigerant fluid, such as ammonia, evaporates in the evaporator Ill and diffuses into an inert gas, 5 such as hydrogen, to produce a refrigerating effeet. The resulting gaseous mixture of refrigerant and hydrogen flows from evaporator l0 through conduit l4, gas heat exchanger [5, and conduit l1 into an absorber Hi. In absorber I8 10 the refrigerant gas is absorbed by a suitable liquid absorbent, such as water. The inert hydrogen gas is returned to evaporator I0 through conduit IS, the gas heat exchanger l5 and conduit 20; and the enriched absorption liquid is con- 15 ducted to an accumulation vessel 2|, and thence through a liquid heat exchanger 22 to generator 23. e

By heating generator 23, as by a gas burner 24, refrigerant is expelled from the absorption 20 liquid, liquefied in an air-cooled condenser 25, and then returned through conduit 26 to evaporator III to complete the refrigerating cycle. The weakened absorption liquid from which refrigerant has been expelled is conducted from 25 generator 23 through, liquid heat exchanger 22 and conduit 21 into the upper part of absorber l8. The generator 23 and liquid heat exchanger 22 may be embedded in suitable insulating material 28. A conduit 29 is connected to the lower 0 part of condenser 25 and the gas circuit, as at the gas heat exchanger l5, for example, so that; any non-condensible gas which may pass into the condenser can flow to the gas circuit and not be trapped in the condenser. 5 In accordance with this invention the cooling element In is independently heated to cause melting of frost that is formed thereon, so that the need for'modifying the operation of the refrig eration-system to defrost the cooling element is 40 avoided. Although heating of the cooling element may be effected by any suitable source of heaa'it ispreferred to utilize heat from a part of the refrigeration system to heat the cooling element and thereby cause melting of frost. The

heat transfer system for transferring heat from a part of the refrigeration system, such as generator 23, for example, to cooling element ill includesan evaporation member 30 which is in good heat exchange relation with generator 23 and embedded in the insulating material 28. The evaporation member 30 is connected at its upper end by an inclined conduit 3|, casing 32, and conduit 33 to a condenser member 34 which serves as the heating element of evaporator l0. The

condenser member 34 is in the form of a looped coil which may be formed integrally with or secured in any suitable manner to a side wall of evaporator H). To conduct heat effectively to the inner portions of the layer of frost heat transfer fins 34' are provided at the side of cooling element l0.

The casing 32 is connected to the horizontal ends of conduits 3| and 33. To the lower part of casing 32 is secured an expansible bellows 35 having a lower end plate 36 with which is integrally formed a piston 31. A pin 38 extending upward from piston 31 is secured to an upper end plate 39'of a second expansible bellows 43 which is smaller in diameter than bellows 35. The bellows 40 is secured to the upper part of casing 32, and, together with casing 32 and bellows 35, forms a chamber 42. A spiral spring 43 disposed about bellows 35 is connected or secured at its upper end to casing 32 and is connected or secured at its lower end to end plate 36, so that the weight of piston 31 and pin 38 may be partly or fully counter-balanced.

Extending upward from the upper end plate 39 is a pin 44 having an enlarged head 45 which is adapted to be engaged and held by a pair of leaf springs 46 fixed to a pair of arms or plates 41 which are secured to casing 32. The upper end of pin 44 is connected to a wire 48 which extends upward and is wound about and secured at its end to a pulley 49. The pulley 49 is fixed to a rod 53 which extends through the rear insulated wall of cabinet l2 and an opening in a front plate 5| of the cooling element ID. A lever 52 is secured to the inner end of rod 50. to rotate pulley 49 and thereby raise pin 44 from a lower position to the upper position shown in Fig. 2.

The evaporation member 30, chamber 42, condenser member 34, and connecting conduits 3| and 33 form a hermetically sealed circuit adapted to contain a suitable volatile fluid for transferring heat from generator 23 to cooling element Hi. When the refrigeration system is in operation and burner 24 is heating generator 23, liquid in evaporation member 30 is evaporated. The vapor passes upward through conduit 3| chamber 42, and conduit 33 into condenser member 34. The vapor is condensed in member 34 and flows downward through conduit 33 and back to evaporation member 30 where it is again When the cooling element I0 is substantiallydefrosted, the pin 44 is below the position shown in Fig. 2, with the upper end of the enlarged head 45 hearing against the lower end of leaf springs 46. In such lower position the expansible bellows 40 is contracted and bellows 35 is elongated with the piston 31 being in its lower position. With piston 31 in its lower position, a maximum quantity of liquid can be held in the lower part of chamber 42 which constitutes an inactive portion of the heat transfer system, and liquid con densate formed in member 34' and flowing toward member 30 is trapped in chamber 42, The

volume of the lower part of chamber 42 is such that, when the enlarged head 45 of pin 44 is hearing against the lower ends of leaf springs 46 and 'not positively engaged and held by the latter,

the condensed vapor is trapped in chamber 42 and cannot fiow back to evaporation member 30. Under these conditions whatever liquid there is in member 30 continues to evaporate until member 30 is depleted of liquid, and thereafter no heat is transferred from generator 23 to cooling element Hi.

When a layer of, frost has formed on cooling element I0 and it is desired to defrost the same, lever '52 in front of cooling element In is turned in a clockwise direction whereby rod 50 and pulley 49 are rotated. This causes Wire 48 to be wound about pulley 49 and pulls pin-44 upward from its lower position to its upper position shown in Fig. 2. With such upward movement of pin 44, the bellows 4!! is expanded and bellows 35 is contracted. This moves piston 31 upward whereby liquid is caused to overflow from chamber 42 or'the inactive portion of the system into conduit 3| and fiow into evaporation member 30. The liquid is evaporated in member 30 and condensed in member 34 in the active portion of the system, thereby giving up and rejecting heat to frost formed on the cooling element. Liquid formed in member 34 flows back to member 30 and is again evaporated. I

When the cooling element In is substantially defrosted the pin 44 is caused to move downward to its lower position, as will be presently explained, so that condensate formed in member 34 is trapped in chamber 42 and cannot flow back to evaporation member 30. The liquid in member 30 continues to evaporate until this member is depleted of liquid, whereupon transfer of heat no longer takes place from generator 23 to cooling element I0. When the pin 44 is moved downward the pulley 49 is caused to rotate in a counter-clockwise direction and lever 52 is moved back to its initial position from which it can be subsequently moved to initiate defrosting when a layer of frost has again formed on cooling element l0.

When the cooling element I0 is substantially defrosted and the liquid in the heat transfer 1 system is trapped in the chamber 42 the temperature of the cooling element and condenser member 34 is relatively low, assuming that the refrigeration system is being operated. When the cooling element is coated with a layer of frost and piston 31 is raised. to its upper position, vaporization and condensation of the volatile fiuid takes place to transfer heat from generator 23 to cooling element l0. With heat being transferred from generator 23 to condenser member 34, the temperature of the condenser member increases to such a value that heat is transferred to the frost and remains at such increased temperature until the cooling element is substantially defrosted. When condenser member 34 is no longer in contact with ice or frost its temperature rises" suddenly. This temperature rise of condenser member 34 after cooling element In is substantially defrosted is utilized in the embodiment just described to terminate automatically the transfer of heat to cooling element It), as will now be explained.

The physical characteristics of the volatile fluid selected are preferably such that; when the condenser member 34 is at the increased temperature during defrosting, the pressure existing in 70 all of the "butane is trapped in chamber 42, and

in the system is substantially equal to atmospheric pressure the forces acting on the upper and lower end plates 36 and 39 are substantially the same and no movement of bellows 35 and 46 will tend to take place. If the predetermined pressure existing in the system is slightly above atmospheric pressure the downward force exerted on lower end plate 36 will be greater than the upward force exerted on upper end plate 39 due to the fact that the latter is smaller in area. The greater-this predetermined temperature is above atmospheric pressure, the greater will be the net downward force tending to move pin 44 out of engagement with leaf springs 46. During this period when member 34 is in contact with ice and frost and the heat transfer system is at the predetermined pressure, therefore, the leaf springs 46 should be sufficiently strong to keep pin 44 and piston 31 in the upper position shown in Fig. 2.

When the cooling element is substantially defrosted and condenser member 34 is no longer in contact with ice orfrost, the temperature of member 34 rises suddenly. Since the temperature of member 34 is increased, the pressure in the heat transfer system increases to a value above the pressure existing when the member 34 is in contact with ice or frost. The bellows 35 and 46, pin 44 and leaf springs 46 are so arranged that at this increased pressure the net downward force exerted on lower end plate 36, due to the greater diameter of bellows 35, is sufllcient to cause bellows 35 to move downward and move the upper end 45 of pin 44 out of engagement with leaf springs 46.

The liquid condensate no-w formed in condenser member 34 is trapped in chamber 42, as explained above, and liquid cannot flow back .to evaporator member 30. When member 36 is depleted of liquid and all of the liquid has accumulated in chamber 42, heat transfer no longer takes place from generator 23 to cooling element I0. When it is again desired to initiate defrosting, lever 52 is turned to raise pin 44. so that it will be engaged and held by leaf springs 46,

. whereby liquid flows from chamber 42 into memher 36 to again effect heating of cooling element It.

- In any case, irrespective of the volatile fluid "used, the leaf springs 46 and spiral spring 43 may be of such strength that, during heat transfer the tension of spiral spring 43 and the frictional engagement of leaf springs 46 and pin 44(- Among the volatile fluids that may be used;

for example, butane possesses such physical.

characteristics that it is particularly desirable in a system of the present type. If it is assumed that the refrigeration system is in operation and the cooling element is substantially defrosted and at a temperature of about 10 C.,the pres-- sure existing in the heat transfer system when butane is used is about .7/kg/cm It is further assumed that substantially all of the air has been removed from the heat transfer system before it is'charged with butane. Under these conditions the pressure in the system is below atmospheric pressure. If lower end plate 36 is one square cm. greater in area than upper end plate 39 the resultant force acting upward on lower end plate end plate for an expansible bellows 62.

36 is about 0.3 kg. greater than that acting downward on upper end plate 39. The greater force on lower end plate'36 tends to move pin 44 into engagement with leaf springs 46, and the latter must be of such strength that the elongated head 45 cannot pass upward between the lower ends of the springs.

When cooling element It) is coated with a layer 'of frost and piston 31 is moved to its upper position by turning lever 52, evaporation and condensation of butane takes place to cause melting of frost. The temperature of condenser member 34 is now increased to a value sufficient for heat transfer to the frost, as explained above, and the pressure of butane in the heat transfer system for this temperature is about 1.0 kg/cm and substantially equal to atmospheric pressure. Due to ,the fact that the pressures within and outside the system are substantially equal no displacement or movement of the bellows 35 and 40 takes place. When member 34 is no longer in contact with ice or frost, however, and it is assumed that the temperature of condenser member 34 further-increases to about +10 C.,

the pressure of butane in the system is about 1.5

by chamber 42 will be sufficiently large to trap liquid butane and prevent butane from flowing back to the evaporation member 36. The leaf springs 46 in any particular .case may be so shaped that a greater force is required to move pin 44 in one direction than in the other direction. a

It will now be understood that heat may be supplied to-cooling element ill to effect defrosting without disturbing the operation of ,the refrigeration system. With such an arrangement it is not necessary to suspend or reduce the refrigerating effectproduced by cooling element l0 during a defrosting period. Ffurther, defrosting can be effected very rapidly because heat is conducted directly to the cooling element, the

heat transfer system preferably being so constructed and arranged that a rapidrate of. heattransfer is effected.

In addition to supplying heat to cooling element l0 to effect defrosting, the heat transfer system also may be arranged to supply heat to the thermally insulated space H to maintain the latter substantially at a desired temperature. This is particularly desirable "when the source of heat is more or less diflicult to regulate. Such a modification of the embodiment just described is illustrated in Figs. 3 and 4 with parts similar to those shown in Figs. 1 and 2 indicated by the same reference numerals.

In Figs. Sand 4 the upper ends of a U-shaped bracket 66 are secured to the casing 32. The lower part 61' of bracket 60 serves as an upper The be lows 62 is providedwith a lower end plate 63 which is fixed to the lower part of a rectangular frame 64. The frame 64 is at right angles to bracket 66 and is secured at its upperpart to lower end plate 36 of bellows 35. A spiral spring 65 is interposed between the upper part of frame 64 and lower part of bracket 60. To the lower end plate 63is connected one end .of a flexible in chamber 42.

tube 66 which is connected at its other end to a thermal bulb 6I located in the thermally insulated space I The bellows 62, tube 66, and bulb 61 constitute an expansible fluid thermostat containing a volatile fluid which increases and decreases in volume with corresponding changes of temperature.

When-the storage space H is at the desired temperature, piston 31 is in its lower position and the liquid in the heat transfer system is held When the temperature of storage space H falls below the desired value, however, the volatile fluid in the expansible fluid thermostat becomes reduced in volume whereby expansible bellows 62 contracts. Since the upper end plate 6| of bellows 62 is immovable due to the fact that it is fixed to the lower part of bracket 68, the contraction of bellows 62 will I cause its lower end plate 63 to move upward.

movement of lower end plate 36, whereby bellows 35 is contracted and piston 3! is raised. Raising of piston 3! causes liquid to-overflow from chamber 42 and pass into evaporation member 38. With liquid in member 38 the transfer of heat takes place from generator 23 to cooling element I0, thereby raising the temperature of storage space II.

. When the storage space tends to rise above the predetermined temperature, the volatile fluid in the expansible fluid thermostat increases in volume to cause the lower end plate 63 to move downward and carry with it the frame 64. Downward movement of frame 64 lowers end plate 36 of bellows 35 whereby the latter is expanded and piston 31 is lowered, thereby trapping liquid condensate in chamber 42 and preventing flow thereof into evaporation member 38. When member is depleted of liquid, transfer of heat from generator 23 to storage space II no longer takes place.

Instead of automatically terminating the sup- .ply of heat to cooling element In in accordance with an increase in pressure in the-heat transfer system, a control mechanism may be provided whereby defrosting is terminated in accordance I III which is arranged during defrosting to contact a layer of frost II formed on cooling element In. 'The arm I8 may be formed integrally with an arcuate-shaped plate I2 having one part I3 of greater radius than another part I4. The plate I2 is eccentrically pivoted at 75 to a disk I6 which is secured to a pin 11. The pin 11 is journaled in the forked arms I8 of a depending bracket I9 which is secured at its upper end to a casing 80. The casing 88 serves as a housing for the expansible'bellows and is provided with an opening at its lower end through which extends a contact member'8l secured to lower end plate 36. The contact member 8| "is arranged 82 having-a short horizontal arm on which is mounted a pin 83. The pin 8 3.is urged or biased upward by a spring 84 and is-adapted to fit into a recess 85 in disk I6 to prevent rotation of the latter.

To the lower end plate 36 of bellows A coil spring 86, which is disposed about an enlarged end of pin 11, is connected at one end to disk I6 and at its other end to one of the arms I8 of bracket I9. The spring 86 is so arranged about pin 11 that it is effective to move disk I6 in a clockwise direction when pin 83 is moved downward and out of recess 85. A crank 81 is secured to pin H for turning disk I6. To keep arm I0 bearing against the layer of frost II during defrosting, the plate is caused'to move in a counter-clockwise direction by a coil spring 88 having one end connected to plate I2 and the other end connected to bracket I9.

When it is desired to initiate defrosting the parts of the control mechanism are moved into the position shown in Fig. 5, as will be presently explained. In' this position the piston 31 is in its upper position and liquid overflows from chamber 42 into evaporation member 38, whereupon transfer of heat to cooling element I8 takes place. As the frost on cooling element I8 melts and decreases in thickness, coil spring 88 is mo-ving plate I2 in a counter-clockwise direction so that the erid of arm III is constantly contacting the melting frost. This counter-clockwise movement of plate I2 continues until the part I4 thereof moves under the projecting member 8|, whereupon the latter suddenly moves downward from part I3 to part I4 due to the tension of coil spring 43. When this occurs the cooling element is substantially defrosted and plate I2 has turned in a counter-clockwise direction such a distance that the end of arm I0 is contacting a side of cooling element I 0. The downward move- -ment of projecting member 8| moves piston 31 evaporation member 30, whereupon transfer of heat to cooling element I8 no longer takes place.

When projecting member 8| moves downward bracket 82 is also moved downward whereby pin 83 moves out of recess 85 in disk I6. With pin 83 no longer locking disk I6 in position, the coil spring 86 is effective torotate disk I6 in a clockwise direction to the position shown in Fig. 8.

.The parts of the control mechanism are so proportioned and arranged that arm I6 is moved away from the cooling element III a considerable distance 'so that there will be no danger of. the contactarm' freezing fast to the layer of frost that. is subsequently formed on the cooling element. Withsuch counter-clockwise movement of disk I6 the plate I2, due to the fact that it is eccentrically pivoted on/disk I6, can move downward a suflicient distance to assume the position shown in Fig. 8 with part I3 directly beneath the downward projecting member 8|.

When it is again desired to initiate defrosting of cooling element I0, crank 81 is turned in a counter-clockwise direction to put spring 86 under tension and also locate recess 85 directly above thelocking pin 83. The bracket 82 is then moved upward so that pin 83 will lock disk 16 in position and also force projecting member 8| vupward, whereupon piston 3! is raised and liquid will overflow into evaporation member 38. When bracket 82 is moved from the lower position shownlin Fig. 8 to the upper position shown in Fig. 6, contact arm I0 is again brought into contact with the layer of frost and spring 88 is put under tension to effect counter-clockwise movement of plate I2 as frost melts and becomes smaller and smaller in thickness on cooling element l8.

Although several embodiments of the invention have been shown and described, it will be apparent to those skilled in the art that various modifications and changes may be made without departing from the spirit and scope of the in- .vention. It is therefore contemplated to cover all modifications and changes which come within the spirit of the invention, as pointed out in the following claims.

What is claimed is:

1. Apparatus for defrosting a cooling element of a refrigeration system and including a flrst member associated with a source of heat and another member in thermal relation with the cooling element, means connecting said members to form a closed circuit containing a volatile fluid, said circuit having an active portion in which fluid is adapted to circulate to transfer heat from the source of heat to the cooling element and an inactive portion adapted to contain fluid in a liquid state, and means responsive to the pressure existing in said circuit for controlling the quantity of liquid in saidactive portion to control the transfer of heat from the source of heat to the cooling element. 1

2. Apparatus for defrosting a cooling element of a refrigeration system and including a first member associated with a source of heat and another member in thermal relation with the cooling element, means connecting said members to form a closed circuit containing a volatile fluid, said circuit having an activeportion in which fluid is adapted to circulate to transfer heat from the source of heat to the cooling element and an inactive portion adapted to contain fluid in a liquid state, and means including a movable member adapted during heat transfer to said cooling element to bear againstfa diminishing layer of melting frost on said cooling element for controlling the quantity ofliquid in said active portion to control the transfer of heat from the heat source to the cooling element. Y

3. Apparatus as defined in claim 2, in which said means for controlling the quantity of liquid in said active portion is so constructed and arranged that said movable member is moved away from the surface of the cooling element when the transfer of heat no longer takes place, so'that said movable member will not freeze fast to said cooling element.

4. Apparatus'for defrosting p cooling element of a refrigeration system and comprising a first -member associated with a source of heat and a second member in thermal relation with the c ooling element, means connecting said members to form a closed circuit containing a volatile fluid, said circuit having an active portion in which fluid is adapted to circulate to transfer heat from the heat source to the cooling element and an inactive portion adapted ,to contain fluid in a liquid of frost formed on the latter, said last-mentioned means being so constructed and arranged that, when said second member is no longer in contact with ice or frost and the pressure in the circuit increases, substantially all of the fluid in the circuit is trapped in said inactive portion whereby transfer of heat no longer takesplace from the heat source to said cooling element.- 5. In a method of refrigeration attended by formation of frost or ice, that improvement which consists in melting said frost or ice by conducting heat thereto in a fluid medium, and controlling flow of said medium by pressure of the medium.

6. A method asset forth in claim 5 in which said fluid undergoes vaporization and condensation.

7. A method as set forth in claim 5in which said fluid is circulated between a place of vaporization and a place of oondensatiom'the latter being in heat transfer relation with the frost or ice, and condensate is withheld from said place of vaporization by increase in pressure of the vapor.

8. In a refrigerator having a cooling surface subject to' formation of "frost or ice, a fluid heat transfer circuit having a portion in heatexchange relation with said cooling surface for melting said frost or ice, and means for controlling flow of fluid in said circuit responsive to pressure in the circuit.

9. A refrigeratorfas set forth in claim 8 in which the fluid in said circuit undergoes vaporization and condensation, and said control means causes withholding of condensate from the place of vaporization responsive to increase in pressure.

10. In a refrigeration system including a cooling element subject to formation of frost orice thereon, means for supplying hot gaseous fluid to melt said frost or ice, and means to control the supply of said fluid responsive to the pressure thereof.

ll. Refrigeration apparatus having a" high temperature part and a low temperature part, the latter being subject to formation'of frost or ice thereon, means forming a path, for flow of fluid for conducting heat from said high temperature part to said low temperature part forcausing melting of said frost or ice, and means for 13. The combination with a refrigeration system having a' cooling element subject to' formation of frost or ice, of means for transferring heat to said frost or ice at 'a temperature and rate to cause meltings thereof, and fluid pressure operated means for controlling said heat transfer means.

14. In refrigeration apparatus having a thermally insulated space nd a cooling element arranged to cool said sp ce and subject to formation of frost or ice, a first member associated with a source of heat and another memberassociated with said cooling element, conduit means conholding substantially all of the liquid fluid in the circuit and being arranged to receive liquid from said othermember, and means including a control element responsive to a temperature condition affected by said cooling element for causing liquid to flow from said second portion into said first portion whereby transfer of heat takes place from said heat source to said cooling element.

' 15. An absorption refrigeration system having a high temperature place of heating where vapors are generated and a low temperature place where heat is abstracted by evaporation of liquid to produce a refrigerating effect, the place of heat abstraction being subject to. formation of frost or ice, structure providing several paths of flow for fluid from the place of'heating to the place of heat abstraction, one of the paths of flow including a portion in which vaporous fluid from the place of heating is condensed to liquid and from which liquid flows to the place of heat abstraction for evaporation therein, another of the paths of flow being controllable to supply vaporousfluid from the place of heating to the place of heat abstraction when desired, the heat from vaporous fluid at the place of heat abstraction being absorbed by the frost or ice .so that heat is transferred to the frost or ice at a temperature above the melting point thereof and at a rate sufficient to cause melting of the frost or ice. I

16. An absorption refrigeration system having a high temperature place of heating where vapors are generated and a low temperature place where heat is abstracted by evaporation of liquid to produce a refrigerating effect, the place of heat abstraction being subject to formation of frost or ice, structure providing several paths of flow for fluid from the place of heating to the place of heat abstraction, one of the paths of flow including a portion in which vaporous fluid from the pace of heating is condensed to liquid and from which liquid flows to the place of heat abstraction for evaporation therein, another of the paths of flow being adapted to supply vaporous fluid from the place of heating to the place of heat abstraction, the heat from vaporous fluid at the place of heat abstraction being absorbed by the frost or ice so that heat is transferred to the frost or ice at a temperature above the melting point thereof and at a rate sufficient to cause melting of the frost or ice, and means controlling the supply {of vaporous fluid to the place of heat abstracion.

1'7. An absorption refrigeration system having a high temperature place of heating where vapors are generated and a low temperature place where heat is abstracted by evaporation of liquid to produce a refrigerating effect, the place of heat abstraction being subject to formation of frost or ice, structure providing several paths of flow for fluid from the place of heating to the place of heat abstraction, one of the paths of flow ineluding a portion inwhich vaporous fluid from the place of heating is condensed to liquid and from which liquid flows to the place of heat abstraction for evaporation therein, another of the paths of flow being adapted to supply vaporous fluid from the place of heating to the place of heat abstraction, the heat from vaporous fluid at the place of heat abstraction being absorbed by the frost or ice so that heat is transferred to the frost or ice at a temperature above the melting point thereof and at a'rate suflicient to cause melting of the frost or ice, and means responsive to a condition representing substantially a defrosted state of the place of heat abstraction-to stop flow of vaporous fluid to the place of heat abstraction. 18. In the art of refrigeration with an'absorptlon refrigerating system including vaporizing fluid at a place of vapor expulsion, condensing the vaporized fluid to liquid at a place of c'ondensation, and flowing liquid from the place of condensation to a place of vaporization for vaporization therein to produce a refrigerating eflect,

the place of vaporization being subject to formation of frost or ice, the improvement which consists in addition in vaporizing liquid and flowing the vapors to the place of. vaporization, the heat from the vapors being absorbed by the frost or ice so that heat is transferred to the frost or ice at a temperature above'the melting point thereof and at a rate sufficient to cause melting of the frost or ice.

sorbed by the frost or ice so that heat is trans- I ferred to. the frost or ice at a temperature above the melting point thereof and at a rate sufficient to cause melting of the frost or ice, and controlling the heating of liquid to control flow of vaporous fluid to the place of vaporization.

20. In the art of refrigeration with an absorption refrigerating system including 4 vaporizing fluid at a place of vapor expulsion, condensing the vaporized fluid to liquid at a place of condensation, and flowing liquid from the place of condensation to a place of vaporization for vaporization therein to produce a refrigerating eifect, the. place of vaporization being subject to formation of frost or ice, the improvement which consists in addition in flowing vaporized fluid to the place .of vaporization, the heat from' the vaporized fluid being absorbed by the frost or ice so that heat is transferred to the frost or ice at a temperature above the melting point thereof and at a rate suflicient to cause melting of the frost or ice, accumulating liquid at a place of accumulation in the path of flow of the vaporized fluid to stop flow of the vaporized fluid to the place of vaporization, and removing liquid from the place of accumulation to permit flow of vaporized fluid to the place of vaporization.

21. In the art of refrigeration with an absorption refrigerating system including vaporizing fluid at ya place of vapor expulsion, condensing the'vaporized fluid to liquid at a place of condensation, and flowing, liquid from the place of condensation to a place of vaporization for vaporization therein to produce a refrigerating effect, the place'of vaporization being subject to formation 'of frost-or ice, the improvement which consists in addition in vaporizing liquid to form vapors, flowing'the vapors to the place of vaporization, and condensing the vapors by absorption of heat by the frost or ice, so that heat is transferred to the frost or ice .at a temperature above the melting point thereof and at a rate suflicient to cause melting 'of the frost or ice.

22. An absorption refrigeration system having a high temperature place of heating where vapors are generated and a low temperature place where heat is abstracted by evaporation of liquid to produce a refrigerating effect, the place of heat abstraction being subject to formation of frost or ice, structure providing several ,paths of flow for fluid from the place of heating to the place of heat abstraction, one of the paths of flow including a portion in which vaporous fluid from the place of heating is condensed to liquid and from which liquid flows to the place of heat abstraction for evaporation therein, another of the paths of flow being adapted to supply vaporous fluid from the place of heating to the place of heat abstraction, the heat from vaporous fluid at the place of heat abstraction being absorbed by the frost or ice so that heat is transferred to the frost or ice at a temperature above the melting point thereof and at a rate sufficient to cause melting of the frost or ice, a liquid trap in said other path of flow operative to stop the supply of vaporous fluid to'the place of heat abstraction, and means to remove liquid from said trap to cause vaporous fluid to be supplied to the place of heat abstraction.

23. An absorption refrigeration system having a high temperature place of heating where vapors are generated and a low temperature place where heat is abstracted by evaporation of liquid to produce a refrigerating effect, the place of heat abstraction being subject to formation of frost or ice, structure providing several paths of flow for fluid from the place of heating to the place of heat abstraction, one of the paths of flow including a portion in which vaporous fluid from the place of heating is condensed to liquid and from which liquid flows to the place of heat abstraction for evaporation therein, another of the paths of flow being controllable to supply vaporous fluid from the place of heating to the place of heat abstraction when desired, the vaporous fluid supplied to the place of heat abstraction being condensed by absorption of heat by the frost or ice so that heat is transferred to the frost or ice at a temperature above the melting point thereof and at a rate suflicient to cause melting of the frost or ice.

24. In a refrigerator having a cooling surface subject to formation of frost or ice, a fluid heat transfer circuit in which a heated fluid is adapted to flow and having a portion in heat exchange relation with said cooling surface, the heat from fluid in said portion being absorbed by the frost or ice, so that heat is transferred to the frost or ice at a temperature above the melting point thereof and at a rate suflicient to cause melting of the frost or ice, and means including a movable member adapted during heat transfer to the frost or ice to contact a. diminishing layer of melting frost or ice on said cooling surface to control flow of heated fluid in said circuit.

25. The combination as set forth in claim 24 in which said means for controlling flow of heated fluid in said heat transfer circuit is so constructed and arranged that said movable member is moved away from the surface of said cooling element when heated fluid no longer flows in said circuit to said portion, so that said movable member will not freeze fast to said cooling surface.

WILHELM GEORG KGGEL. PAUL STRANDBERG. GUNNAR GRUBB.

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