US1744968A - One-way heat interchanger for cooling units of refrigeration apparatus - Google Patents

Description

Jan. 28, 1930 D F, Err 1,744,968

7 ONE-WAY HEAT INTERCHANGER FOR 00 N6 UNITS OF REFRIGERATION APPARA Filed Nov. 30. 1928 2 Sheets-Sheeu' l Jan, 28,1930. [1 KEITH 1,744,968

, ONE-WATHEAT INTERCHANGER FOR COOLING UNITS OF REFRIGERATION APPARATUS Filed Nov. 30. 1928 2 Sheets-Sheet 2 Patented Jan. 2s -1 93o;

. I ED S ATES; .eATENTQoFF IcE mm s. KEITH, or CLEVELAND smears, omo, nssmnon TO rnnrncnon sfrovE come-Amt, or crnvnnann, 01110, n ponronarxon or omo own-way any]: mnncnnnenn son coonmc- -unrrs or nm'nigmrronarrmws application flied November 80,1928. iSerial No.,322',7 99.

. This invention 'relates to grefrigeration apparatus and more particularly to a oneway heat interchanger for use w1th the cooling units of such apparatus;

5 In practically all, kinds of refrigeration- 7 machines, while itjis desirable to'mamtain a substantially uniform temperature in the refrigeration compartment, and a temperature at or below freezing in the so-called freezing 10 space or chamber, it.has'heretofore proven diflicult of attainment because there is a pronounced fluctuation in the temperature of the cooling units. In refrigeration apparatus of the intermittent absorption type the temperature of the cooling unit is considerably higher duringthe comparatively brief heating-condensing periods than during the alternate and protracted cooling-absorption periods; and in other ,types of refrigeration machines the cooling unit is naturally of higher temperature during the defrosting operations than at other times. The fundamental purpose of this invention is'to provide means that is very effectual in transmitting heat from the cold space of the apparatus to the cooling unit, when the-temperature'of the latter is below that of the cold space, but is practically without efiect in transmitting heat from the cooling unit to said space when the aforesaid conditions are reversed. Here it may be explained that the cold spacemay consist of either or both the refrigeration compartment or the socalled freezing space or chamber, or their means for stabilizing the temperature of the cold space. of refrigeration apparatus,'-or for 4o preventing the temperature-of the freezing space or chamber. from attaining a value abovegthe freezing point of water, thereby to protect any ice that has been frozentherein frommelting. I

15 The'invention may be defined briefly asconsisting of an enclosure apart of whose interior constitutes achamber'to the contents 1 of which the cooling. unit of the refrigeration apparatus is exposedtogether with ,a body W of elastic fluid that occupies the chamber, and

iing in the evaporator.

a body of liquid inthe enclosure that isin. intimate heatexchanging relation to, or in: contact with, the cooling unit when the volumefof elastic fluid is diminished by'the relatively low temperature of'the cooling unit, and is displaced out of intimate heat exchanging relation to, or out of contact with, the cooling unit when the volume of elastic fluid is caused to expand by the relatively v high temperature of the cooling unit, the o 'bodyof liquidbein atlall times in intimate heat exchanging re ation to the cold space \I of the apparatus J Another, object is to sov arrange the parts that a' thermal-siphon circulation of the as. liquid is set up when said liquid is in intimate heat exchanging relation to, or in contact with, the cooling unit thereby to more efi'ec tually transmit'the heat units from the cold space to the cooling unit when, the. tem- 7o perature of the latter is below that of said space.

Other objects and advantages of the invention will become apparent as this description proceeds, among w ich is the provision of a 'relativelysimple and substantial construction by which the invention may be efliciently and economically reduced to practice.

In the accompanying drawings which form a part hereof Fi 1 is a more or less dia amso matic sectional ront elevation of a refri eration apparatus embodyin one form 0 the invention; Fig. 2 is a sectional .detail on the line 2 2 of Fig. 1; Fig. 3 is a fragmentary view, similar to Fig. 1 but embracin only a the cooling unit of the apparatus, exhibiting I,

a modification of the invention, and Fig. 4 is a section on the line of Fig. 3. The invention is of especial value in connection with refrigeration apparatus of the rator from the generator absorber and the relm5v atively hot refrigerant condensate is collect- For this reason I I haveelected to disclose the invention as asso- .c'iated' with such a refrigeration apparatus and fora more complete understanding of the apparatus per se reference may be had to my co-pending application Serial No. 242,574, filed December 27, 1927.

The agparatus consists, generally, of a generator a sorber 1 in which, at the start of a cycle of operationiis contained practically all of the refrigerant liquor that is present in the system, the level of which at such time is indicated by the dotted. line a. The refrigerant liquor consists of a suitable refrigerant, such as ammonia, and an absorber therefor, such as water. Situated inoperative relation to the generator absorber is a heating device 2, the same being conventionally shown in the present instance as-an oil burner. When the heating device is set in operation, the refrigerant liquor in the generator absorber starts to boil and the vapors therefrom rise through the conduit 3 and pass through a portion 4 thereof thatconstitutes a dehydrator to a condenser 5 which is shown as a coil and which with the dehydrator 4, is enclosed within a casing 6 that contains a suitable cooling medium, such as water. vAll, or nearly all, of the absorbent vapors are removed from those of the refrigerant in the dehydrator 4 and the remaining vapors descend through the condenser 5 and are reduced to liquid form therein and are discharged through a tube 9 in the evaporator 10. According to the present-illustration, the evaporator 10 consists of a cylindrical vessel from the top of which a dome 11 rises, the tube 9 passing downwardly through said dome and terminating at-its lower end within a sump 12 that is shown as formed by a depression in the bottom of the evaporator, The above described portion of the cycle of operation is what is known as the heating-condensing period and during this period the refrigerant condensate accumulates within the evaporator to about the level indicated by the dotted line b.

When the heat is removed from the generator absorber, as by theshutting. down of the heating device 2, what is known as the cooling-absorption period begins. It may be explained here that during the heating-condensing period the pressure in the. system rose to a very considerable degree and, as is commonly known to those familiar with the subject, the high pressure then prevailing contributed tothe condensation of the refrigerant. At the beginning of the cooling-absorption period the pressure falls quite rapidly and under this lowered pressure condition and under the influence of the relatively warm surroundings of the evaporator 10 the relatively pure refrigerant therein starts to vaporize, the vapors passing from the evaporatorthrough a return conduit 13 to-the generator absorber 1 where they are readily absorbed. by the relatively weak liquor which at this time stands at about the level indicated by the dotted line 0 in the generator absorber.

Any residue liquid remaining in the evaporator at the conclusion of a cooling-absorption period, and which consists of a mixture of refrigerant and such of the absorbent vapors as were distilled over into the evaporator during the previous heating-condensing. period, is transferred to the generator absorber through a siphon 15 whose short leg terminates adjacent the bottom of the evaporator 10 and whose long leg depends into the generator absorber, the siphonic action taking place very early in the heating-condensing period when the pressure. within the system is rising with the greatest rapidity. A full and complete-description of the operation of the siphon will be found in the aforesaid application.

The evaporator 10 is situated within the upper portion of the refrigeration compartment 18 of the apparatus. This compartment is enclosed by insulated walls 19. and 20 of a suitably constructed cabinet, and through the top thereof, which is formed by the wall 20, is extended the dome 11 of the evaporator.

lVith reference to the embodiment of the invention illustrated in Figs. 1' and. 2, what has been referred to hereinbefore as an enclosure is designated 25 and consists of rectangular casings 26 and 27 and a conduit 28 through which the lower portions of said casings communicate. The evaporator 10 is housed within the upper portion of the casing 26, and below it is located a casing 29 that encloses the so-called freezing space or chamber 30, the front of the casing 29 being open and joined to the front wall of the casing 26, as shown in Fig. 2. Ice trays 31 are adapted to be placed within the freezing space or chamber 30, and they are shown'as equipped with the usual removal partitions 32 .for forming ice cakes when water is placed within the trays.

A body of non-freezing liquid, so called because its freezing point is below the lowest temperature attainable by the apparatus, and which may consist of a mixture of water and alcohol, occupies the lower part of the enclosure 25 and separates two bodies of elastic fluid that are present within the upper portions of the respective casings 26 and 27, that contained within the former casing be ing intimately subjected to the temperature of the evaporator 10. The elastic fluid. in this case may be aircontaining, to some extent possibly, vapors of the liquid.

During the heating-condensing period,

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when the relatively hot refrigerant condensate collects in and warms up the evaporator 10, the fluid within the upper portion of the tionof the latter casing, the liquid level in level of the liquid in thecasin'g 2 7 rising and compressing the fluid in the upper porfeet the temperature of the liquid, especially since the fluid is a very poor conductor of heat, and as a consequence the liquld remalns 1 substantially at the low temperature caused by its direct contact withthe evaporator 10 during the previous cooling absorption period. fl

Assume now that the succeeding coolingabsorption' period has begun. The fluid in,

the upper; portion of the casing 26 is caused to contract under the cooling influence of the evaporator 10 and this permits the liquid to rise into contact with the evaporator, the

body of the elastic fluid inthecasing 27 exanding to its normal volume as the liquid evel in said casing lowers to substantially that nowprevai'lingin the casing 26. .When the liquid is in contact. with the. evaporator a thermal-siphon circulation is set up, the liquid in immediate contact with the evapo rator becoming chilled and flowing down alongside the evaporator and across the top and down'to the rear. of the casing 29 and then, as it abstracts heat from the air in the space or chamber 30 and in the compartment 18, it flows upwardly along the sidewalls of the casing to where it again comes within the cooling influence of the evaporator and as 'a result thereof flows downwardly along the wall of the evaporator as before.

It will thus be seen that thiscirculation of the liquid promotes heat .int'erchangeibetween the cold space of the apparatus which may be either or both the freezing space or ,chamber 30 or the refrigeration compartment 18) and the evaporator 10.

In the form of the invention illustrated in Figs. 3 and 4, the enclosure, which in this case is designated generally by the-numeral 35, is made -up of a cylindrical shell 36 that surrounds the evaporator 10 andavessel 37 that is situated below the shell, and'tubs or conduits 38 and 39 through which the interiors of the shell and vessel cpmmunicate,

the former tube terminating atits upper end near the top of the shell 35 and theilatter.

.terminating. at-its lower'end adjacent the bottom of the vessel. A casing-4'0 enclosing the freezing space or chamber 41 is situated within the lower portion of the vessel 37 and is open atf i'ts forward end where it joins the front wall of said vessel. Ice trays 42 are vaccommodated by-the casing 40 and they are equipped withremovable' partitions 43. A

ba'fliei45 extends across the top of the casing '40 and its forward end is provided with an aperture-wherewith the lowerend of the tube 38 registers,. the tube and bafile being suitably secured together about said aperture.

is the same in the two embodiments illustrated in the drawings, the principle of operatior in-the form disclosed in Figs. 3 and 4 is slightly different from that of the first de- While in essential respects the invention scribed form. In this case, a volatile liquid,

such as alcohol, is employed, and'dui'ing the cooling-absorption period the liquid is dis-.

tributed within the enclosure 35 substantiah ly as shown in [the drawings, the liquid level in the vessel 37 being slightly above the baflle 45, while, that in the shell 36 is slightly above the pp f the tu e 38, theTtopofth' vessel 37 containing vapors of the liquid under tension;

' qUnder; the conditions just described, .a'

"39 to the vessel 37 Where itextracts heat-from the air within" the refrigeration compartment '18 and from that within the freezing space (ir chamber 41, and the liquid being thus raised in temperature flows upwardly beneath the baflle 45 and through the tube 38 where itagain comes within thetchilling-influence of the evaporator 10.

The foregoing conditions prevail until the heating-condensing period is initiated,-when the evaporator becomes warm and vaporizes the volatile liquid adjacent it until the volume of the vapors displace all liquid from the shell 36, the liquid level in the vessel 37 rising in consequence thereof. "Thus, during the I heating-condensing period, the liquidis out i of contact with the evaporator and the temperature of the liquid is-aifected very slightly by the warmth of said vessel. It may also be explained -.that during the cooling-absorption period (when"the vapors 1 of the liquid within the shell 36 condense and (create a suction that draws the liquid up-f wardly into the shell) -the thermal-siphon therein and thus promoting its upward flow.'

In the form of the invention just described, the shell -36 is preferablyenclosed by a acket 47 of insulating material so as to more effectively protect the refrigerationcompartment 18 from the warmth of the evaporator 10 during the heating-condensing period, the.

v vessel 37 being'leftexposed to the cold space of' the apparatus so, as 'to effect as intimate a heat exchanging relation between said cold space and the volatile liquid within'the 'vessel as possible.

To the same ends, the upper portion of the casing 26 in the form of the invention illus- I ing;occupiedbyelastic fluid and the enclosure being so arranged with respect to the cooling unit that the fluid in said chamber is subjected to the temperature of the unit whereby when the volume of fluid in said chamber is caused to diminish by the low temperature of the unit the liquid will be elevated in said chamber intocontact with the cooling unit.

2. In combination with the cooling unit of a refrigeration apparatus and the space from which heat is abstracted thereby, an enclosure a part of whoseinterior constitutes a chamber. a body of liquid in the enclosure and a body of elastic fluid occupying said chamber,

' the enclosure being so arranged that the liquid is in heat exchanging relation to the aforesaid space while the fluid is subjected to the temperature of the cooling unit, the liquid being in intimate heat exchanging relation to the cooling unit when the fluid is of reduced volume due to the low temperature of the cooling unit but is displaced out of intimate heat exchanging relation to the cooling unit when the relatively high tempera ture of the unitcauses the volume of the fluid to beduly increased.

3. In combination with the cooling unit of a refrigeration apparatus and the space from which heat is abstracted thereby, an enclosure a part of whose interior constitutes a chamher that is sealed except for its communication with the remainder of the enclosure, the

cooling unit being exposed to the interior of said chamber, a body of elastic fluid in the chamber and a body of liquid inthe enclosure that is in heat exchanging relation to the aforesaid space and is in contact with the cooling unit whenthe volume of the elastic fluid is reduced by the relatively low temperature ofthe unit, the liquid being displaced out of contact with the cooling unit when the volume of fluid is duly increased by a rise in temperature of the cooling unit.

4. In combination with the cooling unit of a refrigeration apparatus, an enclosure a part of whose interior constitutes a chamber, a body of liquid in the enclosure and a body of. elastic fluid in said chamber, the enclosure being so arranged with respect to the cooling unit that the fluid in said chamher is subJected to the temperature of the unit whereby when-the volume of said fluid is caused to diminish by reason of the low temperature of the unit the liquid will be elevated within said chamber into contact with the cooling unit, and a casing enclosing a so-called freezing space that is disposed within the portion of the enclosure occupied by the body'of liquid.

5. In combination with the cooling unit of a refrigeration apparatus and the space from which heat is abstracted thereby, an enclosure involving two chambers, a body of liquid in the enclosure, said body se arating said chambers and wherewith the a oresaid space is in intimate heat exchanging relation, the chambers being occupied by elastic fluid and the enclosure being so arranged with respect to the cooling unit that the fluid in one of said chambers is subjected to the temperature of the unit whereby when the volume of-fluid in said chamber is diminished by reason of the low temperature of the unit the liquid will be elevated in said chamber into intimate heat exchanging relation to the cooling unit.

6. In combination with the cooling unit of a refrigeration apparatus, an enclosure involving two chambers, a body of liquid in the enclosure separating said chambers. the chambers being occupied by elastic fluid and the enclosure being. so arranged with respect to the cooling unit that the fluid in one of said chambers is subjected to the temperature of the unit whereby when the fluid in said chamber is caused to diminish I in volume by the low temperature of the of a refrigeration apparatus, an enclosure involving two chambers, a body of liquid in the enclosure separating said chambers, the chambers being occupied by elastic fluid and the enclosure being so arranged with respect to the cooling unit that the fluid in one of said chambers is subjected to the temperature of the unit whereby when the volume of fluid'in said chamber is caused to diminish by reason of the low temperature of the unit the liquid will be elevated within said chamber into contact with the cooling unit, and a casing enclosing a so-called freezing space that is disposed within the portion of the enclosure occupied by the body of liquid.

8. In combination with the cooling unit of a refrigeration apparatus and the space from which heat is abstracted thereby, an enclosure involving two chambers, a body of li uid in the enclosure separating said cham ers and wherewith the aforesaid space is in intimate heat exchanging relation,,the chambers being occupied by elastic fluid and the cooling unit being enclosed by one of the chambers whereby when the fluid in said chamber is caused to contract in volume by the low temperature of the unit the liquid will be elevated within said chamber into contact with the unit.

9. In combination with the cooling unit of a refrigeration a paratus and the space from which heat is abstracted thereby,a vessel enclosing said unit, a second vessel communicatin with the former vessel, each vessel containing elastic fluid, and a body of liquid Within the vessels and separating said bodies of elastic fluid, the aforesaid space being in heat exchanging relation to the bOdy of liquid, the liquid being elevated into contact with the cooling unit when the elastic fluid surrounding it is caused to diminish in volume by the low temperature of the unit,

the liquid being depressed out of contact with the cooling unit when the volume of said elastic fluid is increased by a rise in temperature of the cooling unit.

10. In combination with the cooling unit of a refrigeration apparatus and the space from which heat is abstracted thereby, a shell enclosing said unit, a vessel in heat exchanging relation to the aforesaid space, means through which the shell communicates with said vessel below the minimum liquid level therein, and a body of volatile liquid in the vessel and a part of which is drawn into the shell into contact with the cooling unit when the temperature of the latter is low enough to condense the vapors of said liquid that are present in the shell.

'11. In combination with the cooling unit of a refrigeration apparatus and the space from which heat is abstracted thereby, a shell enclosing said unit, a vessel in heat exchanging relation to the aforesaid space, a conduit communicating with and depending from the shell into the vessel and terminating below the minimum liquid level therein, a second conduit extending from below the minimum liquid in the vessel to an elevated point within the shell, and a body of volatile liquid in the vessel and a part of-which is drawn into the shell to a level above the upper end of the second conduit when the temperature of the cooling unit is low enough to condense the vapors of said liquid that are present in the shell.

12; In combination with the cooling unit of a refrigeration apparatus and the space from which heat is abstracted thereby, a shell enclosing said unit, a vessel below the shell in heat exchanging relation to the aforesaid space, a conduit communicating with and depending from the shell into the vessel where it terminates below the minimum liquid level therein, a bafile horizontally disposed within' the vessel below said liquid level, a second conduit that opens at its lower end through said baflie and extends u wardly into the shell, and a body of volat' e liquid in the vessel and a part of which is drawn mto ing the same, a vessel below the shell, means through which the shell communicates with the vessel below the minimum liquid level therein, a casing enclosing the so-called freezing space and situated within the vessel and opening through a wall thereof, and a body of volatile liquid in the vessel and a part of which is drawn'into the shell into contact with the cooling unit when the temperature of the latter is low enough to condense the vlaplclars of said liquid that are present in the s 1e 14.111 combination with the cooling unit of a refrigeration apparatus, a shell enclosing the same, a vessel below the shell, a casing enclosing the so-called freezing space and situated within the vessel and opening through a wall thereof, a conduit communieating with and depending from the shell into the vessel where it terminates below the minimum liquid level therein, a baflie spaced from and extending across the top of the aforesaid casing and being disposed below the minimum liquid level in the vessel, a second conduit opening through the baflie and rising therefrom and communicating at its upper end with the shell, and a; body of vol- I atile liquid in the vessel a part of which is drawn into the shell into contact with the cooling unit when the temperature of the latter is low enough to condense the vapors of said liquid that are present in'the shell.

15. In combination with the cooling unit of a refrigeration apparatus, a shell enclosing the same, a vessel below the shell, a casing enclosing the so-called freezing space situated within the vessel and opening through a wall thereof, a tube communicating with and depending from the shell into the vessel where it terminates below the minimum liquid level therein, a baffle spaced from and extending across the to of the aforesaid casing, a second tube opemng through said bafile and rising therefrom through the top wall of the vessel and through the bottom wall of the shell and terminating at its upper end in the horizontal plane of the to portion of the cooling unit, and a body 0 volatile. liquid in the vessel and a part of which is drawn into the shell to a level above the upper signature.- DAVID F. KEITH.

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