US2286025A - Refrigeration - Google Patents

Description

June 9, 1942. A. R. THOMAS REFRIGERATION Filed NOV. 22, 1959 Patented June 9, 1942 z,zss,oz REFRIGERATION Albert R. Thomas, Evansville, Ind., assignor to Islam], Inc., New York, N. Y.,a corporation of laware Application November 22, 1939, Serial No. 305,578.

1 Claim. (Oi. ez-125) My invention relates to refrigeration, and has for its object to provide an improvement in a heat transfer system in which cooling is produced at a place above a source of refrigeration.

The above and other objects and advantages of the invention will become apparent from the following description and accompanying drawing forming a part of this specification, and of which the single figure more or less diagrammatically illustrates an embodiment of the invention.

The heat transfer system is shown in connection with a cooling element or evaporator III of an absorption refrigeration system employing an inert gas and like that described in my application Serial No. 107,852 filed October 27, 1936, now Patent No. 2,207,838, granted July 16, 1940. The cooling element lO-constitutes a source of refrigeration and includes an outer shell I I which is embedded in' insulation l2. Liquid refrigerant, such as ammonia, entersthe upper part of cooling element Ill through a conduit l4. An inert gas, such as hydrogen,.enters the upper part of the cooling element from the upper end of a cylinder I5 disposed within shell l'l. Liquid refrigerant evaporates and diffuses into inert gas within cooling element II to produce a refrigerating efi'ect. This refrigerating effect is utilized to cool and liquefy a volatile fluid flowing through a coil it which is arranged about the I cylinder l5 and over which the liquid refrigerant flows from an annular vessel 11. In order to simplify the drawings. only the cooling element ll of the refrigeration system has been shown,

an illustration of the other parts of the system not being necessary for an. understanding ofthis invention. The disclosure in my aforementioned application may be considered as being incorporated in this application, and. if desired, reference may be made therein for a detailed description of the refrigeration .system.

The coil l6 constitutes the-condenser of a heat I transfer system which is formed and arranged so that cooling may be eifected at a higher elevation than thecooling element 19. The heat transfer system includes anevaporator I! which is of a flooded type and located at a higher elevation than condenser It. .The evaporator ll is disposed in the upper part of a thermally insulated space I! of a refrigerator cabinet or cooler 23. The cooler or refrigerator cabinet 2| may be of the walk-in type having a door 2! to permit a person to walk into the space l9.

The evaporator l3 includes a receiver 22 having a looped coil 23 connected thereto. -A plu- "insulation 26 retained in a shell 21.

rality of heat transfer fins '24 are fixed to coil 23 to increase the heat transfer surface of the evaporator. The upper Part of receiver 22 is connected by a conduit to the upper part of condenser It. The lower part of condenser i6 is connected to a receiver 9 which in turn is connected to a vertically extending standpipe 3. The receiver 9 and standpipe 8 are embedded in The lower end of standpipe 3 is connected by a horizontally extending conduit 29 to the lower end of a looped coil 29. The conduit 28 extends through an insulated wall of refrigerator cabinet 20 and is inclined upwardly from the lower end of standpipe 3. The looped coil 29 is located near the floor of thermally insulated space l9 and provided with a plurality of heat transfer fins 39 to increase the heat transfer surface .of this part of the heat transfer system. The upper end of coil 29 is connected by a vertically extending riser conduit 3| to the upper part of receiver 22.

A fan a: is arrangedadjacent the looped coil 29 to cause flow of air oven the latter. The fan 32 is driven by an electric motor 33 which is connected by conductors 34 and 35 to a suitable source of electric energy. In the conductor 34 is connected a snap-action switch 48 having toggle arms 36 and 31 pivoted at 39 to a suitable support 39. The arms 39 and 31 at points. intermediate their ends are connected by a spring 49 which is operative to cause the arms 39 and 31 to move with a snap action.

Tothe toggle arm 36 is pivotally connected the lower end of a link member 4!, the upper end of which is connected to anexpansible and conthe space. The bellows 42, tube 44 and bulb 49 constitute an expansible fluid thermostat which is filled with a suitable volatile fluid.

36 and 31 are moved downward from the position shown, the arm 31 engages a contact. 41, thereby limiting downward movement of toggle arm 31. when toggle arm 31 engages the'co'noperation of fan 32 will be started.

The heat transfer system including evaporatact "the circuit for motor 33 is completed and tor l3, condenser l9, looped coil 29 and the inter- I uniform pressure type.

During operation of the heat transfer system, liquid evaporates in evaporator l8 and takes up 'heat thereby producing cold. The vapor formed in evaporator l8 flows through conduit 25 into condenser IS in which the vapor is cooled and condensed by cooling element Ill. The condensate formed in condenser I6 fiows therefrom through receiver 9, standpipe 8 and conduit 28 into looped coil 29. Liquid is raised through riser conduit 3| to the evaporator l8 at a higher level by vapor liquid lift action. This results from heating of liquid in the looped coil 29 and lower part of conduit 3| by air in thermally insulated space 19. Due to such heating vapor bubbles are formed in the looped coil 29 and lower part of conduit 3|. The internal. dimeters of looped coil 29 and conduit 3| are suiiiciently small so that these vapor bubbles cannot freely pass liquid whereby slugs of liquid are raised by vapor liquid lift action. The column of liquid formed in standpipe 8 balances the column of liquid slugs and vapor raised in conduit 3| to provide the necessary reaction head for raising liquid to-the evaporator [8 at the higher level In order to maintain a uniform temperature in thermally insulated space I9, the small looped coil 29 is provided in the heat transfer system near the floor of the cooler'20. The looped -coil 23 is relatively small compared to the evaporator II which is arranged in the upper part of thermally insulated space I! andat which region heat is abstracted to 'maintain the space l9 at a desired low temperature.

When the average temperature in space I9 tends to rise above a predetermined value, the volume of the volatile fluid in the expansible fluid thermostat. increases and the bellows 42 expands sufllciently to move toggle arms 36 and 3! downwardly from the position shown in the drawing and cause toggle arm 31 to engage the contact 41. With toggle arm 31 engaging contact 41 the circuit for motor 33 is completed and fan 32 will start operating. The fan 32 causes air to flow over the surfaces of looped coil 29 lower part of conduit 3! at a more rapid rate when air is caused to flow over these parts by fan 32, vapor bubbles are formed more rapidly and liquid will be raised through conduit ii at a faster rate by vapor liquid lift action.

When the average temperature in space i! tends to fall below the predetermined value, the volatile fluid in the expansible fluid thermostat becomes reduced in volume and bellows l2 contracts sufficiently to move toggle arms 36 and 31 to the upper position shown in the drawing. With toggle arm 31 no longer engaging contact 41, the circuit for motor 33 is opened and the fan 32 stops running. During the periods when fan 32 is not operating, circulation of air takes place naturally in thermally insulated space 19, that is, air cooled by evaporator 88 flows downward to replace warmer air rising in space i9.

The receiver 9 is of sufficient volume to provide a place'of storage for liquid when evaporator I8 is only partly filled with liquid.

In view of the foregoing, it will be clear that the provision of the looped coil 29 in the heat transfer system and the thermostatically controlled fan 32 is particularly advantageous in that a more uniform temperature may be maintained in thermally insulated space Hi. In addition to maintaining a uniform temperature in space l9, desirable forced circulation of air in the space is obtained during the periods when fan 32 is operating.

While a single embodiment of the invention has been shown and described, such variations and modifications are contemplated which fall within the true spirit and scope of the invention, as pointed out in the following claim.

What is claimed is:

In a refrigerator having a storage compartment, a cooling element, a heat transfer system including an evaporator in the upper part of said compartment, a condenser at a level below that of said evaporator and arranged to be cooled by said cooling element and connected to receive vapor from said evaporator, a second evaporator in the lower part of said compartment connected to receive liquid from said condenser, a conduit for conducting liquid from said second evaporator upward to said first evaporator under the lifting action of vapor formed in said second evaporator, a blower located so as to direct a stream of air in said compartment onto said second evaporator when the blower is in operatlon. and a thermostat for starting and stopping said blower responsive to change in temperature of air in said compartment.

. ALBERT R. THOMAS.

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