US1862657A - Refrigerating system and apparatus therefor - Google Patents

Description

2 Sheets-Sheet C. H. BREIDENTHAL REFRIGERATING SY-STEM AND APPARATUS THEREFOR Filed March 26,

June 14, 1932.

June 14, 1932 c. H. BREIDENTHAL 1,862,657

REFRIGERATING SYSTEM AND APPARATUS THEREFOR Filed March 26 1930 2 Sheets-Sheet 2 Patented June 14, 1932 UNITED STATES PATENT OFFICE CHARLES H. IBREIDENTHAIi, 0F BARRINGTON, RHODE ISLAND, ASSIGNOR TO GENERAL FIRE EXTINGUISHER COMPANY, OF PROVIDENCE, RHODE ISLAND, A CORPORATION or DELAWARE REFRIGERATING SYSTEM AND APPARATUS THEREFOR Application ined March 2s, 1930. serial No. 439,006.

This invention relates to improvements in refrigerating systems and apparatus therefor. More especially it has to do With a novel heat absorber or evaporator With improved automatic means controlling the quantity of liquid refrigerant available for evaporation.

In the art of refrigeration the absorption of heat is usually accomplished by the conversion of a liquid refrigerant to the gaseous state. It has been the custom to use a refrigerant which boils or evaporates at a relatively low temperature and this has made it necessary to subject the refrigerant While gaseous, at ordinary room temperatures, to rather high pressure and condense it to liquid. This y pressure increase naturally raises the boiling point of the liquid and heretofore it has been deemed essential to feed this high pressure liquid to the evaporatorthrough a form of reducing valve in order to reduce its pressure and thus bring its boiling point again within the range of temperatures at which the cooling effect is to' be accomplished.

In pursuance of this accepted practice the feed of the liquid refrigerant is usually controlled manually by means of a handoperated needle valve or automatically by means of a diaphragm valve Which responds to pressure generated by the sensible heat of the refrigerant gas after leaving the evaporator. If the rate of supply of liquid to the evaporator is constant, as when a hand valve is set for what is deemed to be the proper rate, one of two undesirable conditions inevitably result. If the available heat evaporates the liquid faster than it is supplied, its level in the evaporator rapidly falls and greatly reduces the effectiveness of the unit. liquid feed exceeds the amount necessary to absorb the available heat, then some of the liquid passes on into the accumulator, ioods the latter and passes thence to the compressor With obviously dangerous results. In the case of the diaphragm valve control. the sensible heat of the evaporated liquid after leaving the evaporator acts upon a separate body of liquid. usuallv anhydrous ammonia, confined in an auxiliary 'system of which the diaphragm'valve constitutes a part. As this separated body of ammonia is expanded or.

If the in the evaporator may be largely converted into gas Without the temperature or sensible heat of the latter being raised sutliciently to affect an opening vof the diaphragm valve. It isonly when the evaporated liquid, that is the gas, is itself raised in temperature that any effect is experienced on the auxiliary body of anhydrous ammonia controlling the diaphragm valve. Consequently there is a very appreciable lag between the change in quantity of liquid in the evaporator and the operation of the diaphragm valve to 'admit more liquid. The result is similar when the control operates to close the diaphragm valve, the liquid in the evaporator may be oversupplied before the temperature of the gas affecting the auxiliary ammonia brings about a closing action of the diaphragm valve. Moreover the employment of the diaphragm valve controlled as above described, requires the addition of other means to entirely cut olf the liquid supply to the evaporator upon a stoppage of the compressor, for if the circulation of the refrigerant continues from the high pressure condenser its sensible heat rapidly increases and effects a further opening of the diaphragm valve with resulting flooding of the evaporator, accumulator and feed lines to the compressor. It may be said that in practice, instead of maintaining a desired quantity of liquid ammonia in the evaporator.l the quantity of liquid available for absorption of heat has been a variable one. In 'consequence of this it has been" thought necessary to provide evaporators of rather large liquidholding capacity in the expectation that with a large amount of liquid Iii)A at hand in the evaporator the heat to be absorbed could be taken u without too reat a reduction of the liqui refrieerant. 'uch practice has led to costly installations which,

particularly in respect to the evaporator, occupy a large space and involve numerous pipe and fitting connections with consequent danger of leakage of the refrigerant. In fact, only in recent years has the art developed to the extent that refrigerating systems have been sufficiently reduced in size to be applicable to domestic use.

The present invention isv directed to the provision of a novel heat absorber' or evaporator whichl can be made small enough for the ordinary house refrigerator or large enough to take care of the cooling rooms in cold storage establishments or the requirements of ice-making plants, and which in intermediate sizes is adaptable to meet the needs of jobbers and retailers in respect to storage spaces, show cases, and the like. The evaporator constructed in accordance with the principles of this invention is so small in size comparcdwith the amount of heat it is capable of absorbinel that the heretofore used methods of supplying liquid to it are quite inadequate, and so a further feature of the invention is to provide means for controlling the supply of liquid to the evaporator to the end that at least a minimum quantity of liquid refrigerant will be ever present for heat absorption. Although iarticularly designed to meetvthe deman( sl of the novel evaporator of this invention, the improved control means are nevertheless applicable to other forms of evaporators.

In the accompanying draWin s are disclosed illustrative embodiments o. the invention. The novel evaporator comprises top andbottom headers and a series ofvertical tubes extending between them provided with heat gathering fins. In the case of direct eoolin as where the evaporator is exposed direct y to the atmosphere of the room or space to be cooled, there is a power driven fan provided close by the tubes to force the air past them, while in the case of indirect cooling, as when another medium such as brine is cooled by the eva orator and then in turn is utilized to absorb eat where the ultisuitable propulsion means for rapidly moving the said medium past the tubes.

' This feature of forced circulation of the air or other medium together with the heat gathering surfaces of the fins, makes it highly essential that the evaporator be amply supplied with liquid refrigerant as otherwise the maximum absorptive capacity of the evaporator can not be realized. Accordingly, there is provided in combination with the evaporator a novel form of control means which insures that the level of liquid refrigerant will not fall below a predetermined minimum. T-hese means com rise a device, here shown in the form of a oat, which responds to changes in level of the liquid refrigerant and actuates other means which govern a valve in the supply line. This valve is located outside the cooled area where it is free from any danger of freezing, and is operated :troni a source of power whose application may be effected by the remote control means of this invention. As will more particularly hereinafter appear, it is not necessary iii connection with the type of control here disclosed to concern oneself with the restriction ofthe supply passage as luis here,- tofore been ciistolnary. On the contrary it is an advantage of the present invention to have the supply valve open quickly and widely enough to very promptly raise the level of the iquid in the evaporator. Furthermore, when this level has been raised it is also desirable to close the valve quickly and with pronounced force, in order that the closure may be complete and not at all susceptible to the leakage which so often attends the generally used types of reduction valves. Thus it is clear that the supply of liquid refrigerant is controlled solely in accordance with the change of liquid level in the evaporator and without regard to the pressure existing in the evaporator or the temperature of the gas beyond it. f, In short, it is one of the purposes of the invention to provide means actuated in accordance with the level of the liquid in the evaporator to control the supply, to the end that the said operating level will be maintained at all times. It is a feature of the invention that a system embodying its principles of control can be applied to either direct or indirect cooling systems, and to new or existing installations. It is also a feature that by employing the control devices which characterize this invention, other more or less com licated and delicately operated devices an( apparatus can be dispensed with, albeit the desired control is actually accomplished.

It is intended that the patent shall cover by suitable expression in the appended claims whatever features of patentable novelty exist in the invention disclosed.

In the accompanying drawings:

Figure 1 is an elevation of a refrigerating ,system embodying the present invention;

4 Figure 2 is a front elevation of the evaporator and associated control device;

Figure 3 is a side elevation of the appa rntus of Figure 2, as viewed from the right with a portion in section as on line 3-3 of Figure 2;

Figure 4 is an elevation in section on line Figure 5 is a plan on section through sonic ure 4;

Figure 6 is an elevation in section on line 6-6 of Figure 3; and

Figure 7 is a perspective of the moving parts of the float actuated switch.

Referring to the drawings, and particularly to Figure 1, the refrigerating system disclosed comprises a compressor 10 adapted to deliver la gaseous refrigerant at high pressure to a condenser 12 wherein tlfe refrigerant assumes the liquid state. From this condenser the liquid flows through feed pipe 14, strainer 16 and al control valve 18 into a casing 20 which. as here shown, serves as an accumulator. From this the liquid continues downward through pipe 22 to the bottom header 24 of an evaporator 26 from which header a series of tubes 28 extend vertically upward to a top header 30. As will later more particularly appear, the liquid refrigerant in the tubes 28 takes up heat which 'boils the liquid into a gas that bubbles upward through the tubes into the top header 30 and passes thence by a suitable connection into the casing 20. This gaseous refrigerant is then drawn through pipe 32 back to the compressor to begin again its cycle of travel and transformation. The compressor 10 is driven by an electric motor 34 receiving power from the wires 36 and 38. One of these wires is connected with the thermostatic switch 40 which operates at predetermined temperatures in the cooled room 42 to stop and start the motor 34. As will later be made clear, when the thermostat operates to stop motor 34 it also effects control of the liquid supply valve 18 to the extent of preventing said valve from being open while the compressor is idle.

Although the evaporator disclosed is of novel design, it is nevertheless to be taken as representative of any type of evaporator which may be exposed to direct contact with the atmosphere'in an enclosed space to be cooled or which may be located in a tank to cool another liquid which in turn is circulated through the region where the ultimate cooling` effect is desired. The evaporator herein shown is an extraordinarily compact and highly efficient one. The tubes 28 are preferably expanded in the header plates 24a and 30a, and are arranged in rows across the i evaporator, the tubes in adjacent rows being staggered. (See Figure 5.) Each tube is provided with a. multiplicity of fins 28a which surround the tube and greatly augment the heat gathering surfaces of the latter. Vhen the evaporator is to be used for cooling an atmosphere there is mounted, on supporting members 44 attached to the bottom plate 24a and the side plates 46. a motor 48 which drives a fan 50 arranged behind and close by the tubes. A series of adjustable louvers 52 are provided across the front of the evaporator for deflecting the cooled currents in an upward direction. If the evaporthe heat gathering surfaces provided both by the tubes and the fins. Because of this and because of the rapid and forced circulation of the said medium, there is an extremely large transfer of heat to the liquid refrigerant in the tubes. This makes it most essential that the tubes be maintained full of the liquid, since the effectiveness of the evaporator is primarily dependent upon the transformation of the refrigerant from the liquid to the gaseous state. The invention enables this desired condition to be realized.

The casing 2O is so positioned with respect to the upper header 30 that when the latter is partly filled with liquid the former will also contain liquid at the same level, here represented by the dotted line 54a in Figure 4. The connection between the top header 30 and the casing 20 is above this level and, as here shown, comprises a iianged outlet 30?) on the header and a complementary anged inlet 20a on the casing. Within the latter, and extending somewhat into the chamber of the casing is a nozzle 56 with opening directed downward, so that in the event of any liquid particles being entrained in the gas passing from the header to the casing, they will be deflected downward into the body -of liquid in the casing and not be carried on with the gas through pipe 32 to the compressor.

The casing 20 is generally of cylindrical shape with one end closed by a deformed plate 58. This plate hasan integral cylindrical offset 58a which constitutes the bearing of a shaft 60 to the side of which is attached the stem 62 of a float 64. The latter is within the casing 20 and rises and falls in N accordance with the change in level of the liquid therein, which asbefore stated is also the level of the liquid refrigerant in the evaporator. A reduced portion 60a of shaft 60 extends through a suitable stufiing box nut 66 and carries at its end a tube 68 containing mercury. This tube is provided near one end with the terminals of two wires 70 and 72 which form parts of a shunt circuit from the main circuit wires 36-38 The wire 70 leads from wire 36 to the tube 68 and wire 72 leads from the tube to the control valve 18. The

shunt circuit is completed by the wire 74 which leads from the valve 18 to the other main wire 38. The tube is arranged crosswise on the end of shaft 60. and is adjustable to accommodate any desired range of levels. When set it is so positioned that when the liquid in casing 20 is at the level 54a and the oat correspondinglyl raised to the position shown, the mercury 1s at the end of the tube remote from the wires 70 and 72, but when the liquid drops to level 54 and the ioat islikewise lowered the mercury is at the opposite end of the tu e and completes the circuit between these wires. While the specific form of float and electric switch disclosed have been found to be extremely satisfactory, it is to be understood that other means might be provided which are responsive to change in level of the liquid and which would effect the operation o other agencies employing either electrical, pneumatic or hydraulic power. e

The completion of the circuit through wires 70 and 72 effects the openin of the control Valve 18 assuming the t ermostatic switch to be closed. The valve illustrated. is of the solenoid type which is commercially available but other suitable types of valves may be employed which are adapted to be opened and closed automatically by the ap"- plication of electric, pneumatic or hydraulic power. It is a feature of the invention, Vhowever, that this control valve need not be restrictive in character but may open wide an close tight, without regard to the fact that the liquid on its approach side is at a much higher pressure than the li uid on its delivery side. Any flash gas whic may be generated by the sudden change of pressure 1n the liquid as it passes the valve simply enters the casing 20 and bubbles to its top. The sudden and complete opening of the valve enables the liquid to rise rapidly. in the casing 20 (as well as in the evaporator) to level 54a, thereby lifting the oat so as to tip the tube 68 and break the circuit of wires 7 0, 72. The valve 18 thereupon closes and this closure may, like its openin be quick and forceful, thus assuring a tig t seating of the valve with no danger of leaka e such as usually follows when valves of t e reducing type are used in refrigerating systems.

Since the level of the liquid in the casing 20 is that ofthe li uid in the eva orator 26 it is evident that' t e latter will e always suppliedwith liquid up to the desired point and thus its most effective performance be assured. Although the evaporation takes place rapidly, with consequent generation o pressure above the liquid in the evaporator, this pressure is also imposed upon the liquid in the float chamber soA that the level therein changes precisely in accordance v with the change of level in the evaporator and regardless of pressure conditions.- Since the llquid can rise no higher than -the predetermined level, there is no need of any trap beyond the casing 20 and the line to the compressor can be a simple pipe 32. Such drops of liquid pletely d short period. Such drainage of moisture as as may be entrained by the gas flowin through the connection 30?) are directe downward by the nozzle 56 and thus do not continue on with the gas into pipe 32.

The evaporator and its associated control means can be made in any size desired to meet the demands of the space wherein cooling is to be effected. It is illustrated as suspended from the ceiling of a room 42 hangers 76, but the relative sizes of this room and the evaporator are quite out lof proportion as a unit of the size depicted will handle a space many times larger than that represented b the room in the drawings. If the space to e cooled contains an unusual amount of moisture, such as at times to cause a frosting of the fins and tubes, the compressor can be stopped by manual adjustment of the thermostatic switch 40. When this switch is o en, there is no energy in wires 70, 72 since t e latter are shunted ro 38 and consequently since it is of the ty e the valve 18 will close to spring shut when its coil is disenergize The fan preferably runs continuously, so that with the compressor idle and the valve 18 closed, the air continues to be circulated through the evaporator.

defrosts the evaporator in a very occurs from the evaporator is caught by the -drip pan 78 and carried away by the rain pipe 80.

As shown the wires 82, 84 leading to the fan motor 48 are attached to a hand switch 86, having three sets o f terminals. Two of these are connected by wires 88, 90 with the main wires 36, 38 ahead of the thermostatic switch With the hand switch thrown as shown in Figure 1, the fan operates continuously. If the switch is thrown downward so as to connect wires 82 and 84 with wires 92 and 94, then the fan will also be controlled by the thermostatic switch 40, since the wire 94 is connected to wire 38 beyond said switch.

1. Apparatus for a refrigerating system, com rising an evaporator having bottom and top eaders and a series of tubes extending vertically therebetween, combined with a casing connected to said bottom header for transfer of liquid refrigerant thereto and connected to said top header for transfer of gaseous refrigerant therefrom; means for f supplying liquid refrigerant to said casing;

and means connected with the casing above the liquid therein for withdrawing gaseous refrigerant therefrom; there being a nozzle associated with the connection between said top header and casing having its outlet opening downward in said casing whereby any liquid entrained in the gaseous refrigerant passing into said casing is prevented from going on with the gas to said withdrawing means.

m the main wires 36,

This forced circulation of the air com- 2. A refrigerating system comprising, in combination, an evaporator having bottom and top headers and a series of vertical ducts extending therebetween; means for circulating the medium to be cooled past said ducts;

a casing connected to said bottom header for transfer of a liquid refrigerant andsto said top header for transfer of the refrigerant in gaseoeus condition, said casing being arranged with respect to the evaporator so that the level of liquid in the casing and evaporator correspond; a supply line connected to said casing for supplying the liquid refrigerant thereto and thereby to the evaporator;

an electrically operated valve in said supply line; a discharge line connected with said casing for withdrawal of gaseous refrigerant; a float in said casing actuated by the changes of liquid level therein; a shaft actuated by said fioat a bulb containing mercury attached C to said shaft and arranged to be tilted by the movements of said shaft occasioned by the movements of said float; electric conductors connecting said bulb and said valve, having open ends within said bulb adapted to be electrically connected by the mercury upon the bulb being tilted to a predetermined position; and a source of electrical power connected to said conductors whereby upon the ends of said conductors being Aconnected by the mercury, the said valve is caused to open and thereby admit liquid refrigerant to said casing.

3. A refrigerating system comprising, in combination, an evaporator havingl bottom and top headers and a series of vertical ducts extending therebetween; means forcirculating the medium to be cooled past said ducts;

liquid level therein; a shaft connected to said float so as to be oscillated by the movements of said float; a power control device attached to said shaft exteriorly of the casing; a source of power; and connections between said device and said valve and said source of power, whereby upon the said device being moved to a predetermined position by the oscillation of said shaft, the said power is applied to effect opening of the supply valve.

Signed at Providence, Rhode Island, this 22nd day of March, 1930.

/ CHARLES H. BREIDENTHAL;

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