US1404457A - Refrigeration apparatus - Google Patents

Description

F. E. MATTHEWS. REFRIGERATION APPARATUS. APPLICATION FILED MAY 1, I918.

Patented Jan. 24, 1922.

v I QZZaw UNITED STATES.

FRED E. MATTHEWS, 0F LEONIA, NEW J REFRIGERATION APPARATUS.

Specification of Letters Patent.

Patented Jan. 24, 1922.

Application filed May 1, 1918. Serial No. 231,877;

To a]! whom it may concern:

Be t known that I, FRED E. MATTHEWS, a citizen of the United States, residing at Leonie. in the county of Bergen and State of New Jersey, have invented certain new and useful Improvements in Refrigeration Apparatus, of which the following is a speci-' fication."

My invention relates broadly to refrigeration apparatus, and, more particularly, to that branch of refrigeration in which a volatile liquid is evaporated under reduced pressure by the low temperature heat absorbed in an evaporator and is subsequently liquefied under high pressure and temperature in a condenser, and primarily to the so-called absorption process in which a refrigerant, evaporated in the evaporator enters into combination in a so-called absorber with some suitable medium hereinafter called the absorbent. Such combinations may take place either physically. in variable proportions toform solutions of various strengths, of which weak and strong liquors such as are employed in ammonia absorption refrigeration machines are the most common examples, or react chemically in fixed proportions to form definite chemical compounds known as addition products of which the ammoniates of certain simple salts such as copper or ammonium sulfate and calcium or ammonium chloride are good examples."

One of the prime objects of my invention is to provide a new, simple, safe and efiioient refrigeration system of the above character adapted to the use of direct heat as well as steam heat in refrigeration machines of small or medium capacity.

A secondary object of my invention is to provide means for the elimination of loss, both of products refrigerated and of refrigeration, due to the inadvertent production of unnecessarily low temperatures. How I have succeeded in accomplishing this end in my system will be readily understood from the following detailed explanation aided by the accompanying drawings all forming a part of this specification. In these drawings, Figure 1 is a semi- V diagrammatic representation in vertical section of the essential parts of the system applied to a refrigerator for household use; that part of the controlling system not pertaining directly to the refrigerant being omitted. Fig. 2 is a' section on line 2-2,

Fig. 1. Fig. 3 isa sectional View of a suit- I able refrigerant passing valve. Fig. 4 is a sectional view of a suitable gas-controlling valve. Fig. 5 is a detail view showing a modification.

Similar reference numerals indicate corresponding parts throughout the several views.

My invention may be best described by a description of its operation, which is most essentially as follows The heating of the element A and cooling of element (J efi'ects the liberation of the refrigerant from-its absorbent in A and causes its liquefaction in C. Cooling the former element so reduces the vapor pressure of the refrigerant-reactant components Within the system as to cause the liquefied refrigerant to boil and evaporate at comparatively low temperature in C after which the refrigerant vapors return to and unite with the vehicle in A. The temperature under which refrigerant evaporation, and consequently refrigeration, takes place in C, may be fixed by the controlling device B, through which the refrigerant vapors pass in returning to A from C.

Duplex refrigerant pressure gage D for' indicating the pressures of the vapors in A and C, and steam pressure gage E are convenient though not absolutely essential ac- I cessories.

Practically, the operation of the non-l1quefiable solid absorber, or more properly reactant, refrigeration machine herein em-- ployed for exemplifying my invention is as follows A reactant 5, Fig. 1, with which the refrigerant combines not only to form the highest addition products possible but with which it must also be combined in such a way as to produce an addition productpf the physical form from which the refrigerant can be most readily separated under dissociation and reunited under formation temperatures, is placed in the pressure resistant generator-absorber A.

Assuming that the absorption cycle has just been completed and that the generation cycle is about to begin, a four-way cock 6 1s first turned so that the water filling spaces 77 can be ravitated out to the limiting low level indicated at 8, and run to waste at 10. Next the valve 6 is turned so that coolin will 11 the water jacket surrounding the water entering through a pipe 11.

condenser C and overflow to waste through a pipe 12. A valve 13, through which the overflow of cooling water from A is controlled when A is functioning as an absorber during the preceding cycle, is now closed and heat, here shown as developed by a gas burner 14, though the heat may come from any desired source, is applied beneath A now actin as a generator. The generatorabsor er A is surrounded by a pressureresistant shell 15 which functions as a steam boiler, and the bottom of this shell is provided with a plurality of externally and internally projecting heating surfaces 15' to facilitate the transmission of heat to the water contained in the shell 15.

The steam caused by the evaporation of the small quantity of water remaining in shell 15 below level 8 fills spaces 7 where it transmits its latent heat through the metallic walls to the vehicle 5, condenses, drops back into the body of water, and is again evaporated. The hot gases passing up through an annular space 16 between shell 15 and-an insulating cylinder 17, superheat the steam, thereby expediting the dissociation process without the necessity of inlation of a certain pressure allows it to pass creasing steam pressure.

When, as may be desirable, steam from an external source is employed, it may be supplied either at such pressure as to correspond with' the temperature desired, 'or lower pressure steam may be used and the temperature raised by superheating as above suggested, or the superheating' may be effected under present day practice by any one of the various known types of superheaters.

The heat transmitted to reactant 5 supplies its negative heat of formation, thereby producing dissociation of the higher addition-product forming compounds into lower compounds and Ifree refrigerant vapor which latter passes out through a pipe 26 leading to valve B, which on the accumuthrough pipe 18 into condenser C now being cooled by water circulating. through its annular water jacket 20 inside of an insulating cylinder 21. The passage of the vapor evolved in the courseof this reaction from the reactant material to a space 22, and from space 22 to the vehicle during the reaction of formation, may be lfacilitated by the use ofnumerous ducts 23, through perforations (not shown) in the walls of which the gas passes; these erforations being sufficiently small to exclu e the reactant from the ducts. .When the vehicle is a liquid absorbent instead of a solid reactant, the size o f the perforations is not material.

It will be apparent to those skilled in the art, that abnormal steam ressure can be made to function to thrott e the gas flow through the agency of a pressure reducing valve of common commercial form, and, furthermore, that a similar result might be effected by the similar employment of abnormal relfrigerant pressure. Or, if desired, these two controlling forces, steam and refrigerant pressure, may be caused to act upon a single valve 24, shown somewhat diagrammatically in Fig. 4, having two pressure-responsive elements, such as diaphragms, one 43 actuated by steam, and the other 44 actuated by refrigerant pressure, and both acting independently upon a single valve 45, the respective actions of the two diaphragms being controlled by adjustable members such as springs 46, adjusted to impose pressure in a direction opposite to that of the steam and refrigerant pressure. In cases where superheated steam is employed, or it otherwise becomes desirable to employ temperature instead of pressure control, this can be readily accomplished by means of a rod 27 having a high coefficient of expansion, passing through one steam space 7 and actuating the controlling valve directly or through a motion transmitting and increasing means 28. Secondary safety means may also be provided in the form of steam and refrigerant pressure relief valves 30 and 31.

The vapor liberated from the charged reactant in the generator-absorber element A under a pressure substantially corresponding to the vapor tension of the addition product involved relative to the temperature to which it is heated, asses to the condenserevaporator element vided with means, in this case a waterjacket, which functions during the generation condensation period to cool the re'frigerant vapor, thereby removing its latent heat of vaporization and causing it to assume a liquid state. contact with the water cooled surfaces de- This element is pro- The liquefied refrigerant in scends as its density increases, gives up the While the refrigerant is being liquefied in I C a part of the refrigeration produced during the preceding evaporation period and stored in the chilled liquid 33, preferably calcium chloride or sodlum chloride brine, occupying a container 34, is cooling the air of the refrigerator by a similar counter-current circulation. Theair of the refrigerator, coming in contact with the outside Of the stratum of brine surrounding the heat-transmitting surfaces .35 will become warmed up to practically. the same temperature as the condensing refrigerant. Only a low percentage of the small amount of specific heat represented by this stratum will be trans- -mitted to the main body of brine, and that only very slowly, because the warm light brine being at the top of the container, on account of its lesser specific gravity, debars heat transfer by convection leaving effective only the slow method of conduction, and that active only during the comparatively short generation period.

When the generator has discharged, and the condenser has received and liquefied a practicable proportion of the refrigerant originally combined with the reactant 5, the generating part of the cycle may be terminated, and the refrigerating part commenced, as follows The four-way cock 6 is now turned so that the cooling water in the jacket 20 surrounding the condenser may run to waste. The heat supply to the generator is interrupted and the steam pressure is relieved. This latter may be accomplished by so turning cock 6 as to allow the steam to pass into the cooling water supply pipe 11 in which it will be condensed. As soon as the steam pressure has been reduced below the water pressure, the direction of the flow will be reversed, the water heated by the escaping steam first entering the spaces 77, and then the cold water, and overflowing to waste through overflow pipe 25 and valve 13.

By proceeding as thus described, a desirable gradual reductioprin temperature from the temperature of the steam to the temperature of the cooling water is effected in A. The consequent reduction in vapor pressure in A, due to the cooling of the reactant, produces a pressure in C materially lower than that formerly due to the temperature of the cooling water in jacket 20, thuspermitting the refrigerant in C to re-evaporate. T 0 thus evaporate, the liquid refrigerant in C must absorb heat equal to its latent heat of evaporation. The container C being heavily insulated, so that heat is not available from without, is at once cooled to the temperature of the evaporating liquid, which then absorbs heat through the submerged heat conducting surfaces 35. Or, in place of the surfaces 35 a coil 40 (Fig. 5) may be used, im-

the case with the internally and externally mersed in the brine tank 34 which extends into the refrigerating chamber of the refrigerator. While it is evident that the heat conducting surfaces 35 may assume any one of a number of different forms, being projected internally to facilitate the transfer of heat from the metal of the container to the refrigerant, as well as externally to transfer the heat readily from the medium to be refrigerated to the metal of said container, the surfaces which I have employed in practice are in the form of radial fins secured to the bottom of the container both inside and outside. Coil 40 (Fig. 5) is deemed to be the equivalent of the externally and internally extended heat conducting surfaces, in that it increases both the surface in contact with the refrigerant and the surface in contact with the refrigerated medium, as is also extended fins 35. This construction of heat conducting surfaces, either the fins 35 or the coil 40, is particularly advantageous with intermittently operated machines, since the chilled, or chilled and partially congealed, brine furnishes a convenient means for storing a considerable amount of refrigeration during the refrigeration cycle proper, and for maintaining refrigerator temperatures during the generation period.

The circulation of the brine downward from the cooling surfaces 35, or coil 40, as the case may be, and upward over the heat absorbing surfaces of the container 34 takes place automatically under slight differences in head thus produced, and with practically negligible friction. The circulation of air 'downward over the exterior surfaces of container 34 and up through the various parts of the refrigerator is also effected by the same means.

In order to maintain a substantially fixed temperature in the refrigerator I employ a pressure regulating means B which, regardless of the pressure in A, allows the 11 refrigerant evaporated by heat absorbed from the refrigerator during the evaporation period in C, to pass back into A only when it exceeds a predetermined pressure. This device B forms the subject matter of my application Serial No. 172,212, filed June 1, 1917, and, as shown in Fig. 3 consists, essentially, of a diaphragm controlled valve, having a spring the pressure of which upon the diaphragm may be varied to suit the par- 1 ticular operating conditions, to allow gas to pass the valve in either direction upon occurrence of said predetermined pre sure upon either side of the valve. For this refrigerant vapor to .exceed a predetermined 12o pressure. the refrigerant liquid must be heated beyond, a corresponding predetermined temperature. Fixing the pressure of the. vapor discharged, therefore, by means of the valve, fixes the temperature of the refrigerant, and subsequently that of the refrigerator.

Though shown for simplicity in Fig. 1 as manually controlled by means of a four-way cock 6, it will be evident to those skilled in the art that the control of the flow of water to and from the shell 15 and water-jacket 20 might be effected through appropriate pressure responsive devices actuated by drop in pressure of the refrigerant or, preferably, because of the greater drop, by that of the steam, where that heating medium is employed. Whether manua ly or automatically effected, the flow of' cooling water is shifted from the condenser-evaporator element C, formerly operating as a condenser, to the absorber-generator element A, formerly operating as a generator, and the cooling water container 20 emptied and container 15 filled, whereupon the recombining of the refrigerant vapors with the vehicle in A made possible by the removal of heat of sufficient intensity. to overcome the chemical affinity of the two substances, causes a material drop in refrigerant pressure in both A and C, causing the liquid refrigerant in C to boil and vaporize.

Container C being effectively insulated by an outside substance 21, assisted by the thin layer of air replacing the cooling water in the container, prevents the ingress of heat from exterior sources. As the temperature of the vehicle becomes more and more reduced by the action of the cooling water in A, a lower pressure will resultin both A and C, until finally, when the temperature corresponding to the pressure in C is reduced to the actual temperature there, the refrigerant in that receptacle, receiving heat through the metallic surfaces in contact with the warmer liquid brine in 33, will boil and evaporate, producing refri eration in proportion to the quantity of liquid refrigerant evaporated, whlch action will continue until the temperature is reduced below that corresponding to the pressure at which the vapors are permitted to pass to the absorber A through the-controlling means B.

Heat is debarred from entering the refrigerant contained in C except through the bottom, the external heat absorbing surface of which may be materially increased by the addition of a plurality of metallic fins 36 hereinabove referred to as the externally projecting portions of the fins 35, these fins 36 being immersed in the brine 33. The brine on being chilled by contact with these fins and with the bottom of container C, acquires practically the same temperature as that of the evaporating refrigerant, since,

' due to its greater specific ravity it encounters a conical partition 3 which guides it into a vertical pipe 38 from the bottom of which it is discharged and forces the lighter, warmer brine up the inside surface of tank 34, and through the horizontal belt of openings 37 in the conicalv partition 37 where 1t encounters the refrigerant cooled surfaces of C and the circuit is a ain traversed.

A single alternate met 0d of construction, above referred to as illustrated in Fig. 5, will be described on account of its involving slightly different principles.

According to this method the refrigerant container C is entirely isolated from the brine tank 34, the bottom of the former, instead of being provided with metallic plates or fins to facilitate heat transfer,

being covered with a non-conducting ma-.

terial to prevent such transfer. The transfer of refrigeration from the former to the latter container is effected in this case by means of a very small pipe 40, one end of which is connected to the bottom of the refrigerant container C by pipe 41 and the other endextending practically to the top thereof through pipe 42.

The small amount of liquid refrigerant occupying the very limited volume of pipe 40 liesquiescent during the generating condensing part of th cycle because the temperature of the (brine) is lower than it is in the case of the refrigerant in C condensing under the same pressure corresponding approximately to the temperature of the cooling water in jacket 20. It will be noted that a countercurrent effect which gives maximum heat transfer takes place between th cold brine on the inside of container 34 and the air of the refrigerator on the outside thereof during that part of the cycle when the temperature differences are least, and when, consequently, means for increasing heat transfer is most desirable. On the other hand, during the remaining part of the cycle, when the differences are greater because of evaporation of the refrigerant within coil 40, the brine chilled by contact with th coil descends next to thewalls of the tank causing a circulation parallel instead of counter-current to the direction of air circulation, thus reducing the heat trans fer and tending to stabilize the operation of the system.

In this construction, liquid refrigerantwill pass from the bottom of container C down throughpipe 41 to the bottom of coil of pipe 40, through which it ascends becoming evaporated by the heat it absorbs from the comparatively large superficial surface of the coil and finally passes out of'th end of pipe 42 as a more or less perfect vapor.

Special means would ordinarily be necessary to insure proper circulation of refrigerant within the coil, and to obviate the necessity for such means I have devised a special design in which the ratio of super ficial area of the ascending coil to the cusurrounding medium bical contents of the descending pipe is very large. This coupled with the fact that a material percentage, or in some cases all, of the descending pipe is insulated, thus pre venting evaporation due to heat absorption and insuring a full gravity head of solid liquid in this member to the bottom of the surface of the liquid in the container, insures circulation in exact proportion to evaporation, and is in-direct proportion to th refrigeration requirements of the refrigerator.

While minor mechanical details of the several elements might, and probably would, be modified to some extent should an aqueous solution, or a liquefiable solid absorbent be substituted for the non-liquefying solid absorbent employed in the apparatus as herein described, the occasions for such modifications ar believed'to be of a nature apparent to those skilled in the art, and the invention as hereinafter claimed is believed to be generally applicable to refrigeration processes employing any absorbent.

What ll claim is:

1. In a refrigeration apparatus, a condenser-evaporator element, comprising a container, a refrigerant container located therein, a partition adjacent thelower end of said refrigerant container and dividing said first mentioned container into two compartments, one of said compartments adapted to contain a cooling'medium surrounding said refrigerant container, a heat absorbing medium in the other of said compartments, and means depending from said refrigerant container and in contact with said heat-absorbing medium for transmitting the cooling efiect of the refrigerant in said refrigerant container to said heatabsorbing medium.

2. In a refrigeration apparatus, a chamber adapted to receive material to be preserved by refrigeration, a two-compartment container provided in its upper compartment with arefrigerant container and its lower compartment extending into said chamber, said upper compartment adapted to contain a cooling'medium surrounding said refrigerant container, a heat-absorbing medium in said lower compartment, and means on said refrigerant container extending into said heat-absorbing medium for transmitting the cooling effect of the refrigerant in said refrigerant container to said heat-absorbing medium, whereby as the heat-absorbing medium absorbs heat from said chamber it will be caused to circulate by the cooling efiect of said refrigerant and said refrigerant will in turn be vaporized, as specified.

In testimony whereof I afiix my signature in the presence of two witnesses.

F. E. MATTHEWS. Witnesses:

MARGUERITE L. GRIMM, ALBERTA-C. MATTHEWS.

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