US2088277A

US2088277A - Absorption refrigerating apparatus

Info

Publication number: US2088277A
Application number: US648501A
Authority: US
Inventors: Normelli Wulff Berzelius
Original assignee: Individual
Current assignee: Individual
Priority date: 1931-12-23
Filing date: 1932-12-22
Publication date: 1937-07-27
Anticipated expiration: 1954-07-27
Also published as: GB417040A; GB416843A; FR751102A

Description

\ July 27, 1937.

w. s. NoRMaLLL AB'soRPTIoN' REFRIVGERATING APPARATUS Filed Doc. 22. 1952 3 Sheets-Sheet 1 w. a. NoRMr-:LLI 2,088,277

ABSORPTION REFRIGERATING APPARATUS Filed Dec. 22, 1952 s sheets-sheet 2 July 27, 1937.

f v J w www d July 27,' 1937.

w. a. NoRMELLl .ABSORPTI'ON REFRIGERATING APPARATUS 3 sheets-Sheer 3 FiledvDec. 22, 1932 W -A u:

Patented July 2 1, 1931 Ansonr'rroN REFBIGERATING APPARATUS Wuur Berze'iius Nermeui, Berlin-Charlottenburg,

Germany Application December 22, 1932. serial No. 648,501

Germany December 23, 1931 s' claims. (ci. ca -11s) My invention relates to absorption refrigerat ing apparatus, and more particularly to apparatus of the intermittent type in which a solid absorbent isV employed which forms a chemical compound with the refrigerant.

In apparatus of the above character care should .he taken not to increase the generating temperatures to an undue value, since otherwise the refrigerant, for instance ammonia, is liable to decompose. Since thenormal'generating temperature in air-cooled apparatus must be consi'derably'higher than that in water-cooled apparatus, the generating temperature in air-cooled apparatus attains-such a value as to cause a decomposition of the refrigerant, particularly when employing certainchemical absorbents. Apart irom these drawbacks which result during the -heating period even at4 normal generatingV temperatures, it may happen that considerable increases in temperature occur in thev generatorabsorber upon failure of the automatic control devices which energize and deenergize the heating element of the generator. In this case the heating element may under circumstances re- @mainv continuously energized, thus causing not only a very rapid increase in temperature, but also an undue increase in pressure in the apparatus, besides the danger of decomposition of the refrigerant and the melting of the solid absorbent. The above-mentioned drawbacks are removed according to the invention by very simple means. An object of my invention is to arrange the generator-absorber cooling surfaces which dissipate the heat of absorption to the atmosphere in such a manner as to insure a cooling by air also during the heating period. By such an arrangement an apparatus is obtainedinwhich no valves or laps are necessary lfor controlling the flow of the cooling meansand in which, furthermore, the temperature doesnot exceed a predetermined value even in the case of the heating element remaining continuously energized, since Athe direct` air-cooling during the heating prevents the temperature from exceeding a predetermined value;

Another object of my invention is to prevent` the decomposition of the refrigerant at increased generating temperatures. This may be accomplished` by providing a coating on the inner surfaces oi the generator-absorber consisting of an iron tank. Consequently, it is possible to attain.

higher generating temperatures than haslhither'- to been the case as well as to employ in the apwhich require in connectionwith air-cooling a considerably higher generating temperature than the hitherto usually employed substances, such as calcium chlorid and strontium chlorid.` Consequently, in this case such binary compounds may be employed in the absorption refrigerating apparatus of the intermittent type which require for the condensation of the refrigerant at a temperature of 40 degrees centigrade artheoretical generating temperature which lies, at least for one of the compounds which with the refrigerant forms the absorbent, above 120 degrees centigrade. The generator-absorber may be constructed in different Ways. For instance, the inner walls of the generator andthe surface of the heat-conducting elements may be provided .with an enamel coating. Furthermore, the entire inner surface may be metallized by dipping it, for

instance, into a lead bath or the like, or the sur face may, for instance, be copper-plated. The

' surface may be also treated with graphite or preferably employed which form a chemical compound with the water taken up by the filling material in the generator.- The quantity of the admixtures is preferably so chosen that'the` filling mass after the generator-absorber( has been charged therewith and after all theV water taken up during the preparation of the-generator has 'been' chemically combined with the admixtures contains still an excess of the admixtures. As admixture, for instance, calciumoxide, strontium oxide, barium oxide or sodium oxide maybe employed. Another agent very suitable for this pur- The latpose is, for instance, aluminum nitride, ter forms together with water ammonia. and aluminum hydroxide. These iinal products have no detrimental eie'ct in the apparatus, for the ammonia continues to act as refrigerant-in the apparatus, whereas aluminum hydroxide is' a solid substance highly resistant to fusion which Vremains rmly embedded in the absorbing mass.

As the refrigerant, ammonia is particularly advantageous, but also ethylamine and higher amines may be employed.

Other objects 'will become apparent from the following specication set forth in referenceto the accompanying drawings in which,-

Fig. 1 showsl a longitudinal sectional view of a refrigerator for domestic purposes equipped with a direct-air-'cooled absorption refrigerating apparatus of the intermittent type;

Fig. 2 shows a horizontal sectional view thereof Fig. 3 shows a longitudinal sectional view of an absorber-generator embodying my invention;

Fig. 4 shows diagrammatically another embodiment of my invention in which an absorption refrigerating machine operating with indirect air cooling is located in a refrigerator;

Fig. 5 shows an apparatus in which special means are provided for insulating the absorbergenerator during the heating period.

Referring to Fig. l, I denotes the absorbergenerator located in the upper part of the refrigerator, said absorber-generator consisting of two vessels heated during the generating period by means of heating elements 2 which are connected to the supply circuit through clock switch I8.

Both absorber-generator vessels are charged with strontium bromide saturated with an operating medium; for instance, ammonia. During the generatingl period the operating medium passes throughthe branch 3 and a conduit 4 into the condenser 5 consisting of a number of elements providedwith cooling ribs,where it is liqueed and then to the intermediate vessel 1 through a conduit 6. The latter is insulated from the cooling chamber 8 by means of a particular insulating medium 9 so as to prevent a heating of the cooling chamber during the condensation. As insulating medium a material with low specic heat, for instance, aluminum foil is particularly suitable for this purpose. The cooling chamber 8 itself is insulated from the surroundling atmosphere by various layers I0 of cork. The intermediate vessel I is connected to an evaporator coil I3 through-a conduit II and `I2. The evaporator coil is located in a brine container I4 which serves as coldstorage tank? The brine takes up during the evaporation of the refrigerating medium a portion of the cold resulting from the evaporation of the refrigerant and gives it up to the cooling chamber during the generating period. The cold storage tank AI4 is preferably charged with liquid having a freezing point between 9 and -10 centigrade; for instance, aqueous'glycerine solution which may be mixed with alcohol. The evaporator coil I3 is arranged close to the walls of an ice container I5 for freezing ice cubes located in the cold storage tank I4. The lower portion of the evaporator coil communicates with a conduit I'I which serves to charge the apparatus. J

, Another cold storage tank I6 is secured to the bottom of the storage tank I4. The latter contains a liquid, for instance, watergnitrobenzene vor the like whose freezing point is higher than the freezing point of the liquid contained in the upper storage tank I4. Ihn this manner it is possible to equalize within wide limits even in the ease of high chamber temperatures the variations of temperature in the cooling chamber' which may occur during the heating period' as a result of the transfer of heat. The absorber-generator I and the condenser 5 are so arranged as to be directly cooled bythe'air passing along-the same.

It may happen that undue increases in pressure in the system occur, in case the heating should be continuously switched in for any reason whatever; for instance, owing to a failure of the clock switch and if a fuse whichis provided for controlling the temperature of the absorbergenerator to prevent an overheating should fail.

To avoid this danger the intermediate tank 'I in which the refrigerant is collected during the generating period is so dimensioned as to take up the total refrigerant condensed during the normal operation and the condenser 5 is so dimensioned as to take up the excess of refrigerant in the case of danger so that a large' free space of condensation is left -so as not to cause undue increases in pressure in the apparatus.

It is advisable to construct the intermediate vessell'I in such a manner that a gas space is left free above the liquid level in normal operation, said space being so large that the vaporolxs refrigerant leaves the intermediate vessel in a dry state during the absorption period.

The absorber-generator container shown in Fig. 3 consists of a cylindrical jacket 2| and an eccentrically arranged inner jacket 22, the cambered plate covers 23, 2'4 being welded to the outer jackets so as to form a completely closed vessel. The inner jacket 22 serves for the reception of the heating element. yThe cover 24) is provided with a branch 25 to which a gas conduit is`connected leading to a condenser (not shown). 26 is a. thermometer pocket projecting into the interior of the absorber-generator. The inner space 21 of the absorber-generator is lled with strontium bromide; In order to prevent decompositions of the refrigerant in the absorbergenerator, the inner walls of the absorber-generator, which come in4 contact with the refrigerant are provided with an enamel coating 20. `Such a coating is also provided on the metallic surface of heat conducting walls in case thel iatterare disposed in the absorber-generator for improving the conduction of heat.

In the embodiment shown in Fig. 4, the auxiliary liquid is displaced during the generating period by the heat exchange surfaces of the solidl absorbent. which may be heated by a coil disposed within a heating pipe 202. The absorber-generator is 20| is the absorber-generatorV connected to the condenser 205 through a con``4 duit 204.

The condenser 205 is arranged in a tank 206 which is preferably charged ywith a solid material to be molten between 40 and 60 centigrade. Sodium phosphate with water of crys- -tallization or another product requiring a; great number of calories for melting and a suitable melting point of about 40 to 60 centigrade may be employed. The condenser 205 is through a conduit 201 connected to the 4storage tank 208 which in turn communicates with the evaporator coil 2 I0. To the lower end of the evaporator coil 2I0, a conduit 2I2 is connected to remove the air and water from the apparatus. The evaporator coil 2I0 is arranged in a cold storage tank 2I9 disposedy in the storage chamber 209. The

cold storage tank 2|! is provided with an open- Y ing for the introduction of a 'container 2I9a for freezing ice cubes. The evaporator coil 2I0 is disposed close to the walls o f 'the container 2I9a. l 'I'he absorber-generator 20| is surrounded by a cooling jacket 203. 2I8 isa container for the auxiliary liquid. During the absorption period the auxiliary liquid circulates through. the conduits 2I4 and 2I5. The'auxiliary liquid container 2I6 is arranged in' the container 206 in such a manner that the heat which escapes during the absorption from the a s'orber-generator by means of the circulation of the auxiliary mey j dium may be partly given up to'tlie salt containedin the container 206. The container 206 is partly arranged in a tank 2.I3 lled with water,A

andJwh'ose upper wall 2I1- consists of porous clay..1t is lined inside with a sheet copper 2I8.' In order to ensure-a good transfer ofl heat from theheatiiig pipeto the absorber-generator a I, y corrugatedf-body 222 surrounds the heating pipe,

said body being-thermally connected to the inner walls of the absorber-generator.

A; j, As soon 4as the refrigerating apparatus upon Eclosure the circuit ofthe coil disposed in the "heating'pipe' 202 isput into operation, the absorber-generator is heated. At the same time the water which at first lls up completely the cooling jacket 203 is` also heated. As soon` as the temperature rises rabout 100 centigrade a slight vaporpressure results in the cooling jacket 203 and the water contained in the cooling jacket 203 is forced into the .container 2I6 through the conduit 2M.' The conduit 2I5 enters in the upper part of the cooling jacket 203 at such a point that the circulation of the auxiliary liquid between the cooling jacket 203 and the container 2I6 will already be interrupted at the beginning of the generating period as a result of the development of vapor. 1f the greatest portion of the water is forced from the cooling-jacket 203 into. the vessel 2I6, a state of equilibrium will be established, since now the walls of the cooling jacket 203 which are relatively poorly insulated from the surrounding air carry off the same amount of heat Whichthe water takes up from the heating pipe 202 as a result of its reduced contact surface. The presg sure in the cooling jacket cannot, therefore, con-l tinue to increase.

Thevolume of the water in the cooling jacket 203 is small in proportion to the volume of the tank so that no appreciable variation of the Water level in the vessel 2IB takes place on removing the water from the cooling jacket. The apparatus is also protected from the danger of being overheated.

If owing to a fault the excess in vapor pressurethrough the conduit 2I4. The water level in the cooling jacket rises, consequently, again and owing tothe heating surface thus increased, a

more eiectiveevaporation` results' so that also I cooling jacket 203 fills up with water. The water is heated and 'circulates between'- the cooling jacket 203 and the storage 4tank 2I6 through the conduits 2M and 2I5. l v A `,Owing to the circulation of liquid during the absorption period, the absorber-generator" 20| will be cooled down both inside and outside. heat of absorption is transferred tothe tank 2I6 as a result of the water circulation. This tank gives uppartially its heat directly to the surrounding air with the aid f the walls communicating with outside atmosphere and indirectly to the water containedin the tank 2I3. The heat which the liquid contained in the -tank .2I3 has Thev theV container to the surrounding air.

A further portion of heat is given up in that thel clay cylinder 2H absorbs water which vaporizes to the air surrounding the cylinder 2'I'1. 'I'he heat of vaporization cools the lcylinder 2I`| which transfers this cooling action to the water in the container 2I3.

The hot water contained in the tank 2I3 may be tapped by means of a water cock 220 for domestic purposes. The hot water is replaced again by cold water which subsequently fills the tank 2 I3 through the water conduit-226 by means of an automatically actuated level responsive device 225 upon Adropping below a predetermined lliquid level in the tank 2I3. The heat of conv densation is taken up by the salt mass contained vtaken up is partly carried oif from the walls of j I Y contact with the air. The surface of theV tank- 206 communicating directly with the surrounding air is so dimensioned that the surface itself is suilicient to carry oif the heat of condensation even if the tanks 2 I3 and 2 I 6 for any reason what'- yever should be empty. A dangerousv increase inv pressure in the condenser 205 cannot, consequently, occur. Further, the parts of the tank 2I3 which give up heat are so dimensioned that they suffice to carry oi the heat taken up withy out the necessity of tapping warm water and of a corresponding supply of cold water. Y By cooling the absorber-generator 20|, the latter acquires again its absorptive properties and the liquid ammonia contained in the heat .I insulated `storage tank 208 is evaporated With the consequent absorption of heat. The heat of evaporation required for this purpose is abstracted by the evaporator coil 2| 0 partly fromV 'the glycerine solution which frewes and partly from the walls of the container for freezing artificial cubes. The frozen 4glycerine solution cools the cooling chamber 209 by means of the walls of the container 2I0. The temperature of the cooling chamber is kept constant, since the thermal capacity of the cold storage tank 2I9 is such that the frozen glycerine solution contained therein will not melt completely during thergenerating period. In Fig. 4, 221 denotes the clock lswitch adapted to limit the heating period. The clock switch is connected to the supply circuit (notshown) through the

conductors

229, 230. The conductors 23| and 232 lead to the heating coil 2I8. A safety switch228 controlled by the float v225 interrupts the heating vcircuit as soon as the liquid level in the vessel 2I3 has lowered to an undue amount.

In the refrigerator shownin Fig. 4, a number of possibilities forcarrying oif the heat of 4abcirculating auxiliary liquid. A second possibility consists in transferring theheat Vof absorption from the auxiliary liquid to the water contained inthe tank 2I3 and thence to the surrounding air by means of the Walls of the tank 2I3. .It is also possible to.dissipate the heat of absorption directly to the surrounding air or to the auxiliary liquidl contained in the tank 2I3 and from the latter to the surrounding air with the aid of a.

special heat storage tank' containing a medium which melts on taking up heat.

In a similar manner, the heat of absorption may be also given up with the aid of the heat storage tank directly to the surrounding air or to a particular auxiliary liquid and from the latter to the surrounding air. For carrying off the heat to the surrounding air either heat conducting walls ofthe liquid v'essel may be used in all thesecases or special means may be provided which ensure the dissipation of heat by vaporization of the liquid. Finally, it is also possible to carry off the waste heat after having been stored up by the supply of hot water. In this case the accumulator vessel may be totally or partly insulated and provided with devices which cause upon the attainment of the maximum temperature of the water a further dissipation of heat to the air. These means shown in combination in Fig. 4 may be employed singly or also in any combination whatever for dissipating the heat.

The above-described utilization of the heat of absorption for domestic purposes is particularly of advantage in such apparatus operating with strontium bromideA as absorbent. In the case of calcium chlorid mostly hitherto employed in apparatus of the intermittent type, the temperature of warm water attainable is limited to about centigrade, if it is desired to produce a suilciently low temperature of evaporation. It is possible by the use of strontium bromide to produce hot water of a considerably higher temperature. One may reckon, for instance, with a temperature of 70 to 80 centigrade. In this manner, the waste heat of the apparatus of the intermittent type may be employed far better for various domestic purposes than has heretofore been the case. The hot water may, consequently, be also used for rinsing dishes. Further, it is also possible to utilize the heat of absorption for the production of hot air which serves to dry or heat a dry chamber which, for instance, may be arranged in the refrigerator. In the embodiment shown in Fig. 5, the absorber-generator is designated by the numeral |0| which, for instance, is lled with zinc chlorid saturated with ammonia. The absorber-generator |0| is heated during the generating period by means of a heating element |02 jacket closed at the top thereof, surrounding an4 absorber-generator. The heat of condensation is carried off by means of the air flowing upwardly in the condenser |04 as a result of the heating so that the 'refrigerant will be liquefied. The

` latter passes from the condenser |04 into an intermediate tank |05 embedded in the insulation of the refrigerator, said tank |05 being connected to an evaporator coil |06. The latter is placed in a cold storage tank |33 arranged in the cooling chamber |08. f |01 is-a container for freezing artificial cubes. l| I0 are heat-conducting corrugated walls which are disposed between the heating element |02 and the inner walls of the absorber-generator |0 I.' By means of the walls I0, the heat is transferred to the solid absorbents .during the generating period. They form cool- -ing ducts whichcpass through the inside of the generator. The outer walls of the absorber-generator lli are also provided with heat conductloperates as follows.

ing walls I of the corrugated type so as to form cooling ducts. The heat conducting walls are brought in a good heat-exchange relation with one another when preparing the absorber-generator ready to be built into the apparatus by dipping them into a zinc bath. To the inner cooling ducts at the lower end thereof, an air duct |I2 is connected in which a motor-driven ventilator H3 is arranged. The latter is secured by means of bolts ||6 so that it may be easily replaced.

vThe cooling device for the absorber-generator During the generating. period the ventilator ||3 is deenergized so that it cannot produce a current of cold air. The air heated by the heat radiating parts of the absorber-generator |0| ows upwardly and cannot escape, since the jacket |09 is not provided with an opening at the -upper part thereof so that during this period a damming up of the air takes place. Sincev the jacket |09 consists preferably of heat insulating material, the loss due to heat during the generating period in this arrangement is-considerably reduced. The condenser is cooled down directly during this time by the surrounding atmosphere. The condenser operates in a proper manner, since in this arrangement one is not dependent upon a current of cold air caused by a ventilator. Furthermore, the volume of the intermediate vessel |05 and the condenser |04 taken together is so great that the total amount of liqiid refrigerant fills up said vessels only to such an extent in case of failure of the clock switch and of the safety device that a free condensation surface is left. In this manner dangerous rises in temperature in the apparatus are prevented.

At the end of the generating period the heating element 02 is deenergized by the clock switch I4 and the ventilator ||3 is in turnput into operation which forces the cold air through the cooling ducts f the absorber-generator in the direction shown by the arrows. The cooling air passes at first into the cooling ducts extending inside the generator through the conduit |2 and thence in counterflow to the cooling ducts arranged on the outer periphery of the generator. This current of air is of particular advantage, since the cold air is directed to the hottest parts disposed inside the absorber-generator which, besides, have smaller cooling surfaces, whereas the parts of the absorber-generator which possess more cooling surfaces come into contact with the already preheated cooling air.

||5 is a thermostat disposed in the cooling chamber |08, which deenergizes the heating device, for instance, the heating element |02 and the cooling device (ventilator H3) of the absorber-generator in case the temperature of the cooling chamber drops below a predetermined value so that on the one hand, a heating period is shortened or, if desired, even completely omitted and, on the other hand, the production of cold is throttled. The thermostat ||5 may also be arranged in the cold storage tank |33. A thermostat |32 is in heat exchange with the absorbergenerator |0I, said thermostat interrupting the circuit for the heating element |0| in case a predetermined maximum temperature is exceeded. It might also be so connected as to operate the ventilator.

I claim as my invention:-

l. A illling material for the generator-absorber of a refrigerating apparatus operating with solid absorbents consisting of asolid absorbent which is mixed with an oxide of an alkali to remove the water taken up by the solid absorbent.

2. A filling material for the generator-absorber of a refrigerating apparatus operating with solid absorbents consisting of a solid absorbent which is mixed with oxide of calcium to remove the water taken up by the solid absorbent.

3. A filling material for the'generator-absorber of a refrigerating apparatus operating with solid absorbents consisting of a solid absorbent which,

is mixed with oxide of strontium to remove the water taken up by the solid absorbent.

4. A iilling material for the generator-absorber of a refrigerating lapparatus operating with solid absorbents consisting' of a solid absorbent which is mixed with oxide of barium to'remove the water taken upby the solid absorbent.

5. In an air-,cooled refrigerating apparatus of I `the intermittent type'designed to cool a cooling chamber, said refrigeratin-g apparatus comprising agenerator-absorber consistingV of an outer cylindrical jacket and an inner concentrically arranged heating tube, an air-cooled condenser, a collecting tank for the receptionb ofthe liquid refrigerant driven off, a valveless refrigerant conduit between said generator-absorber and said collecting tank, the condenser being arranged in said conduit, a heating element for said generator-absorber located in said inner tube, an in sulating material surrounding said collecting tank so as to protect the tank against the cooling chamber air and the outside air, the walls of said outer jacket of the generator-absorber being so arranged that the latter is exposed to the cooling influence of the air coming into contact with the outer surfaces thereof during the absorption as well as during the heating period, said collecting tank being so dimensioned as to take up the refrigerant driven oli' under normal operating conditions and said air-cooled condenser being so dimensioned as to condense the quantity of operating medium driven ofi" when the heating element of the generator-absorber is continuously energized and to take up the excess of condensate without giving rise to vundue increases in pressure..

` WULFF BERzEmUs NoRMELu.