US2267152A

US2267152A - Control apparatus for evaporating coils

Info

Publication number: US2267152A
Application number: US391949A
Authority: US
Inventors: Gygax Ernest
Original assignee: Curtis Manufacturing Co Inc
Current assignee: Curtis Manufacturing Co Inc
Priority date: 1941-05-05
Filing date: 1941-05-05
Publication date: 1941-12-23
Anticipated expiration: 1958-12-23

Description

Dec. 23, 1941.

WITNESSES:

E. GYGAX CONTROL APPARATUS FOR EVAPORATING COILS Filed May 5, 1941 3 Sheets-Sheet 2 BY WINSETNTOS:

TORNEYS.

Dec. 23, 1941. E. GYGAX CONTROL APPARATUS FOR EVAPORATINGCOILS Filed May 5, 1941 3 Sheets-Sheet 3 I N VEN TOR WITNESSES:

. BY W W w W A TTORNEYS.

Patented Dec. 23, 1941 2,267,152 CONTROL APPARATUS FOR EVAPORATING COILS Ernest Gygax, St. Louis, Mo., assignor to Curtis Manufacturing Company,

poration of Missouri Wellston, Mo., a cor- Application May 5, 1941, Serial No. 39;,949

3 Claims.

This invention relates to improvements in control apparatus for evaporating frigeration systems. More particularly, the in-' vention relates to improvements in recirculating apparatus for evaporating coils used in refrigeration systems.

It is an object of the invention to provide an improved recirculating apparatus for evaporating coils used in refrigerating systems.

Recirculating'apparatus for evaporating coils used in refrigeration systems has been known and used for some time. This apparatus is particularly useful with flooded evaporating coils. These coils are ordinarily filled with liquid refrigerant that absorbs heat from the medium to be cooled, and is vaporized. As the vapor boils away, it usually causes some of the liquid refrigerant to surge over the upper confines of the evaporating coil. Since this liquid refrigerant would cause a mechanical breakdown of the compressor if it were allowed to tion line of the compressor, some provision must be made for the liquid refrigerant. The provision that is usually made is a liquid trap or header in which the liquid is caught and separated from the gaseous refrigerant. By use of an injector, the liquid is drawn from the vapor trap and re-injected into the evaporating coil. It can be seen that these recirculating apparatuses not only prevent the flow of liquid refrigerant into the suction line of the compressor, but they also utilize the refrigerating effect of the liquid refrigerant by forcing the liquid refrigerant to vaporize in the coil. Recirculating apparatus of thistype operates satisfactorily with certain types of refrigeration systems, but it does not work at all with'other types of refrigeration systems. These various types of recirculating apparatus have been found to be quite workable with large refrigeration systems where many tons of refrigerating effect is used in each coil, but have been useless with small systems where the refrigerating effect in each coil was not more than two or three tons. These recirculators usually employ an injector that is fed with liquid refrigerant and acts to draw liquid refrigerant from the liquid trap or header. Such injectors are not very efflcient and require the flowof a great deal of liquid refrigerant through them before they generate an appreciable suction. Recirculating apparatus of this type requires such a large flow of liquid refrigerant therethrough before it can operate properly, that it can only be used with very large refrigeration systems. Heretofore, smaller refrigeration systems have been coils used in reunable to attain the flow into the sucwarm and by tions of the coil.

' ation systems that many benefits and advantages of recirculation. The invention provides a novel form of recirculating apparatus that can be used with refrigeration systems of any size at all. This novel form of recirculating provides an injector that is fed with gaseous refrigerant. It is, therefore, an object of the present invention to provide a recirculating. apparatus for refrigeration systems that uses an injector fed with gaseous refrigerant.

Under some circumstances, the amount of re-. frigerant in a recirculating apparatus may be insufficient to insure a supply of refrigerant in the liquid trap. In such a case, the injector will draw gaseous instead of liquid refrigerant-from the liquid trap. This results in a recondensation of the gaseous refrigerant that causes the coil to get short-circuiting of'the coil it renders the coil useless for a time. In all other recirculating apparatus, the recirculation of gaseous refrigerant in one section was accompanied by recirculation of gaseous refrigerant in all sec- The invention obviates this by providing a recirculating apparatus for refrigerrestricts any recirculation of gaseous refrigerant to specified portions of the evaporating coil. It is, therefore, an object of the invention to provide a recirculation apparatus that restricts any recirculation of gaseous refrigerant to specified portions of the evaporating coil.

Many evaporating coils are formed from a plurality of pipes that are integrated into a unitary coil through which the refrigerant may flow. These coils operate fairly well but their operation is not completely satisfactory. The refrigerant must travel a long distance before it leaves the coil. This results in sizeable friction loss in the coil, and increases the pressure drop in the coil. An increased pressure drop in the coil is objectionable since it will result in a reduction in the capacity of the refrigeration system of which the evaporating coil is a part. The invention obviates such a condition by providing an evaporating coil that consists of a plurality of small sections having individual refrigerant controls. It is, therefore, an object of the present invention to provide an evaporating coil consisting of a plurality, of

small sections having individual refrigerant con-' trols.

Evaporating coils made in accordance with the principles of this inveniton are quiet efficient. By using flooded coils, the entire area of the coil may be used to transfer heat to the refrigerant. This permits the use of small coils that have large capacity. The coils are preferably made of ainvention to provide better upper end of j imity to the ends number of relatively short tubes. The use of the short tubes materially decreases the loss in emciency that is due to friction. Where relatively long tubes are used in a coil, the frictional resistance to the flow of refrigerant is quite large and it results in a considerable pressure drop in the evaporator. The pressure drop resultsin the concurrent existence in the evaporator of different temperatures which reduces the efliciency of the refrigerating system of which the evaporating coil is a part. In addition, the use of short tubes in the coils gives a better distribution of the liquid in the coils and this sort of distribution is quite advantageous since it prevents the accumulation of gaseous refrigerant next to the interior of the tubes. Such an accumulation of gas would materially reduce the heat-transferring eificiency of the coil. It is, therefore, an object of the present distribution of refrigerant in an evaporating coil.

Recirculating apparatus for refrigeration systems has formerly required a great deal of control apparatus. Much of the recirculating apparatus needed constant attention other recirculating apparatus has been provided with automatic valves that do away with the need for constant attention. This type of apparatus as well as the apparatus that needs constant attention, is objectionable because its use increases the cost of the refrigeration system. The invention obviates this objection by providing a recirculating apparatus for refrigeration systems that is inexpensive to manufacture and operates without need of attention.

Other objects and advantages of the invention will appear from the drawings and accompanying descriptiom In the drawings and accompanying description,

a. preferred embodiment of the invention has been shown and described, but it is to be understood that the drawings and accompanying description do not limit view of a large size preferred formof plied.

the invention and the in- Fig. 2 is a side elevational view of the evaporator coil shown in Fig. 1.

Fig. 3 is a side elevational view of an evaporator coil, for use in refrigerating compartments.

to which a modified form of the invention has been applied.

Fig. 4 is a plan view of the evaporator coil shown in Fig. 3.

Referring to the drawings in detail, a number of formed tubes are denoted by the numerals meter the refrigerant fed l0, l2, I4. l6, and I8. Each of these formed tubes constitutes a section of the evaporating coil of the invention. Theupper end of each of these tubes communicates with a header 20, and the these tubes preferably extends above the level of the liquid refrigerant in the header. The header 28 may be provided with a baflle plate 22 that is secured ,to the header 28 by supports 23 and extends above the ends of the coil sections l6, baiile plate 22 may be provided with downwardly extending ends 24 that are positioned in proxthe tubes l0, l4, and I8 communicate r specl2, l4, l6, and II. The' of the header 28. A tube 26 as of the said th'e header tively with

capillary tubes

28, 32, and 36.

v'I'h'e capillary tubes

28, 36, 32, 34, and 36 all communicate with the high pressure refrigerant line compressor. The lower ends of tubes l2 and I6 communicate respectively with

tubes

46 and 42 that are connected to injectors 44 and 46. The injectors 44 and 46 comprise a T-shaped Junction having as shown. The upper ends 48 and 50 of injectors 44 and 46 are in communication with the interior of header 26. The injectors 44 and 46 are also connected to

tubes

52 and 54 that communicate with high pressure line 38 through

capillary tubes

38 and 34. The

capillary tubes

30 and 34 are preferably made to present more of a restriction to the flow of refrigerant therethrough than

capillary tubes

28, 32, and 36 present.

In Figs. 3 and 4, a modified form of the invention is shown. This form of the invention is particularly useful in refrigerating compartments wh'ere-the load varies considerably. A high pressure refrigerant line from a compressonwnot shown, is'denoted by the numeral 56. This line 66 communicates with a float valve chamber 58 that contains a float valve 60. This valve'60 is arranged to cooperate with a valve seat 62 to regulate the fiow of refrigerant from the float chamber 58. .The valve seat 62 is connected to a T- shaped junction 64 by suitable tubing. One opening in the T-shaped junction 64 communicates with a capillary tube 66. The capillary tube 66 is connected to the inlet end of finned coil section 68 by suitable tubing. The outlet end of the finned coil section 68 communicates with T-shaped junction 16 and liquid trap 12. The other opening in T-shaped junction 64 communicates with capillary tube 16, which in turn is connected to an injector 18. One portion of the injector 18 is in communication with the lowpressor, not shown.

In the operation of the evaporator coil shown in Figs. 1 and 2, liquid refrigerant is forced into high pressure line, 38. Some of the refrigerant then fiows through

capillary tubes

28, 32, and 36 into tubes I6, l4, and [8 respectively, and fills them with refrigerant. These capillary tubes to the evaporating coil and dispense with the necessity of having expansion valves. The refrigerant in the tubes l0, l4, and I8 absorbs heat from the medium to be cooled, and much of it vaporizes. The capillary tubes 28. 32, and 38 are dimensioned so that sufficient refrigerant enters tubes l8, l4, and 18, to keep them filled with liquidrefrigerant under all conditions and at all times. When, therefore, the amount of refrigerant in the tubes is at its lowest, the tubes I 8, l4, and I8 will be completely filled with liquid refrigeran refrigerant in the tubes is normal or above normal, liquid refrigerant will fiow from the upper ends of tubes l6, l4, and I8. This liquid refrigerant is held in the header 20 and separated from the gaseous refrigerant therein by the baffle plate 22. The gaseous refrigerant will be drawn from 26 through tube 26 by the action of the compressor, not shown. The separation'of the liquid from the gaseous refrigerant prevents the flow of two conical portions when the amount ofsuction line 26 of the compressor. Some proeous refrigerant engages a portion of the refrigrant in the header as it flows through the injector, and draws the liquid refrigerant out of the header. The refrigerant then flows into tubes [2 and I6 where it is vaporized. I have found that the provision of the combination of a capillary tube and an injector is quite necessary to the practical operation of recirculation apparatus for small refrigeration systems. The capillary tube reduces the pressure of the refrigerant to such an extent that the refrigerant vaporizes when it enters the injector. This is quite important since the feeding of the injector with gaseous instead of liquid refrigerant materially increases the efficiency of the injector. This results from the phenomenon that the gaseous reirigerant issuing from the orifice in the injector contacts the liquid refrigerant from the header 20 and is condensed. The condensation of the gaseous refrigerant, results in an appreciable decrease in the volume of the refrigerant in the injector. This creates a vacuum that draws liquid refrigerant from the header 20. Where the injector is fed with liquid refrigerant, there is no condensation of the refrigerant and the injector cannot create much of a suction. By providing an injector that is fed with gaseous refrigerant, I make the use of recirculating apparatus on small refrigeration systems feasible.

By feeding tubes l0, Id, and I8 directly from Because the pressure of this refrigerant has been reduced, the refrigerant will vaporize as it enters the injector. The use of gaseous refrigerant with the injector in the recirculating apparatus permits the use of recirculating. apparatus with small refrigerating systems. This form of evaporating coil is quite useful because it operates at full capacity, has a liquid reserve, recirculates the liquid refrigerant until it is completely vaporized, and restricts any recirculation of gaseous refrigerant to one portion of the coil. It can be seen that evaporating coils made in accordance with the principles of the invention will be quite advantageous.

Whereas a preferred and a modified form of. the invention have been shown and described in the drawings and accompanying description, it is obvious that various changes in form may be the high pressure line of the refrigeration system,

I prevent recirculation of gaseous refrigerant through these tubes. In this form of the invention, any recirculation of gaseous refrigerant would positively be restricted to the coil sections I2 and Hi. If desired, one of these sections could be converted in a section similar to coil sections II), M, and I8. In such a case, any recirculation would be restricted to the one coil section that would be fed by the injector.

The coil shown in Figs. 1 and 2 is quite useful where the load does not vary a great deal in a short period of time, as in air conditioning work. Where, however, the load fluctuates a good deal in a given time, the evaporating coil shown in Figs. 3 and 4 can be used to advantage. Refrigerant from the compressor is stored in the float valve chamber 58 until a predetermined liquid level is reached. The float valve will then open and permit refrigerant to pass therethrough. The greater part of the refrigerant flows into finned tube 68 and "floods it. The capillary tube 66 is dimensioned to introduce an excess amount of refrigerant into the coil. This excess refrigerant will flow out the outlet and into liquid trap 12. The gaseous refrigerant will separate from the liquid refrigerant in the liquid trap I2 and will be drawn from the trap through tube 14. The liquid refrigerant in the trap 12 will be drawn out by the action of the gaseous refrigerant passing through injector l8, and will vaporize in coil 80. The refrigerant that passes through capillary tube 16, is under less pressure than the refrigerant leaving the compressor.

made without; affecting the scope of the invention.

What I claim is:

1. An evaporating coil for refrigeration systems having a plurality of sections, tubing connecting the inlet end of at least one of the said sections of the evaporating coil with the high pressure line from the compressor of the said system, a capillary in said tubing to meter the refrigerant flowing from the high pressure line to the said section, said capillary being dimensioned to provide the said section with sumcient'refrigerant to keep the section "flooded" at all times, a liquid trap, tubing connecting the outlet end of the said section with the said liquid trap, tubing connecting the upper portion of the liquid trap with the suction line of the compressor, an injector in communication with the lower portion of the liquid trap, said injector being connectedto .the high pressure line of the compressor of the said system by tubing, said tubing having a capillary therein to reduce the pressure of the refrigerant flowing into said injector and thereby permit the said refrigerant to change from the liquid to the vapor state, said injector being connected to the inlet end of another section of the evaporating coil, the outlet end of the section that is fed by the injector being in communication with the liquid trap, said evaporating coil being constructed and arranged to have all fluctuations in the level of the liquid refrigerant therein restricted to that section of the coil which is fed by the injector.

, .2. The combination of a multi-section evaporator and control apparatus therefor, comprising an evaporating coil having a plurality of sections, a capillary tube connecting at leastoneofthesections of the evaporating coilwith'thehigh pressure line of the refrigeration system, said capillary tube being arranged to meter the refrigerant flowing into the said section, said capillary tube being dimensioned so that at all times a sufficient amount of refrigerant flows into the said section to maintain the section in a flooded condition and being dimensioned so that most of the time an excess of refrigerant flows into the said section, a liquid trap connected to the outlet end of the said section to receive any excess refrigerant, tubing connecting the upper portion of the liquid trap with the low pressure line of the refrigeration system, an injector in communication with the lower portion of the; liquid trap and any liquid refrigerant in the lower portion of the liquid trap, said injector being connected to the high pressure line of the refrigeration system by a capillary tube, said capillary tube being arranged to reduce the pressure of the refrigerant flowing into the injector to such an extent that the refrigerant will change from th'e liquid to the vapor state as it passes through the injector, said injector being arranged to cause the gaseous refrigerant to contact the liquid rea float chamber and a float valve in the high pressure line of the refrigeration systemtomaintaina supply of refrigerant in the float chamber, a capillary tube connecting at least one of the sections of the evaporating coil with the high pressure line of the refrigeration system, said capillary tube being arranged to meter the refrigerant flowing into the said section, said capillary tube being dimensioned so that at all times a sufflcient amount of refrigerant flows into th'e said section to maintain the section in a flooded condition and being dimensioned so that most of the time an excess of refrigerant flows into the said section, a liquid trap connected to the outlet end of the said section to receive any excess refrigerant, tubing connecting the upper portion of the liquid trap with the low, pressure line of the refrigeration system, an injector in communication with the lower portion of the liquid trap and any liquid refrigerant in the lower portion of the liquid'trap, said injectorbeing connected to the high pressure line of the refrigeration system by a capillary tube, said capillary tube being arranged to reduce the pressure of the refrigerant flowing into the injector to such an extent that the refrigerant will change from the liquid to the vapor state as it passes through the injector, said injector being arranged to cause the gaseous refrigerant to contact the liquid refrigerant from the liquid trap and draw it out of the liquid trap, said injector being connected to th'e inlet end of another section of the refrigeration coil and being arranged to feed the said other section, and the outlet end of the said other section being in communication with -the liquid trap, said control apparatus being adapted to restrict any recirculation of gaseous refrigerant to specified portions of the refrigeration system.

' ERNEST GYGAX.