US2123021A - Refrigeration system - Google Patents

Description

July 5, 1938. H. A. PHILLIPS 2,123,021

REFRIGERATION SYSTEM Filed Dec. 23, 1935 II WI.

I0 3| l5 INVENTOR HAPPY A. PH/LL/PS BY MA.

ATTORNEY Patented July 5, 1938 UNITED STATES PATENT OFFICE arsam ass-nonunion srsrsu Harry A. Phillips. Chicago, 111.

Application December 23,1935, Serial No. 55,815 1: Claims. (01. ss-iss) This invention relates to a system of refrigeration and more particularly to a new method and apparatus to secure improved circulation of a refrigerant in the evaporator of a refrigeration system.

A principal obiect of this invention is to utiline a portion of the total amount of incoming refrigerant used in an evaporator to obtain improved circulation of all of the refrigerant within the evaporator.

A particular object of the invention is to provide injetor means associated with a refrigerating coil or evaporator and operating at a uniform continuous rate to secure constant circulation of refrigerant within the coil.

A further object of the invention is to operate theinjector means with .one portion of the total amount of the refrigerant fed into the evaporator coil and utilize said injector means to increase the entering velocity into the coil of the remaining portion of the refrigerant.

'A still further object of this invention is to make. use of such an injector meansin connection .with a float valve and surge drum adapted to operate a refrigerating coil in a "flooded ,condition." v

- Because of the latent heat of evaporation the greatest refrigerating effect or absorption of heat units takes place when a change of state is brought about in the refrigerating medium. With a.-given surface area of evaporator it follows that thegreatest refrigerating effect will be obtained if the liquid refrigerant is changing its state to .vapor throughout the evaporator. The advantages of such flooded operation" of an evaporator are generally recognized.

The rate of heat transmission to an evaporator and the amount of useful work which a given evaporator can perform depends upon a number oil-factors, such as material, thickness and cleanliness of theevaporator walls; temperature drop into theevaporator; and resistance to heat transmission of the fllm formed at the surfaces of.the;evaporator. The resistance of the fluid fllm depends upon the kind of fluid .and the character of the motion of the fluid along the wall. The resistance of a film of gas is very high. It has been estimated that in certain .cases over 95% of the available temperature drop is required to force the heat through the gas film. If the gas is given a high velocity the resulting sweeping action partially destroys the film and greatiy decreases the resistance to heat transmission. It is well established that the rate of heat transmission is dependent on the velocity of the fluid along the plate.

The importance of maintaining circulation of the refrigerant within the evaporator is obvious.

The change in the refrigerant from liquid to gas serves to constantly renew the gas fllm adjacent to the inner surfaces of the evaporator and a great increase in the overall efliciency of the evaporator results from the use of applicant's invention as described herein.

Every evaporator. will inherently possess, in varying degree, resistance to the motion of the refrigerant passing through it. This resistance varies with the design of the evaporator, size of the passages and the length of path for the re- 15 frigerant to follow. Different methods of overcoming the frictional resistance have been tried, but one major dii'iiculty encountered with the methods and apparatus-of. the prior art, is the periodic action which sets up a wave motion of 20 the refrigerant within the evaporator. This wave motion or "surging greatly decreases the efliciency of the evaporator.

The method and apparatus of this invention supplies a remedy for the difliculty described and 25 secures a greatly improved circulation of the refrigerant. The total quantity of liquid refrigerant fed into the evaporator is divided into two parts, one of which serves, through the use of independent injectors, as a constant accelerating 3 force to maintain an active circulation of refrigerant in the evaporator, and also cooperates with the other portion of refrigerant to increase its velocity entering the heat absorbing coils. By the use of a continuous feed of the one portion, a. constant current of refrigerant is maintained through the evaporator, thus minimizing the periodic action or surging.

It is pointed out that the use of an injector, or other feed, in series with a float valve (or thermally operated valve) which controls the total quantity of refrigerant used in the evaporator, will not secure the beneflcial results obtained by applicant.

To these and other ends the characteristic features and advantages of my improvement will more fully appear in the following description and the accompanying drawing and illustrations thereof.

In the drawing, in which like reference numerals designate like parts, Fig. l is a plan view of an evaporator coil having an embodiment of my invention in combination therewith.

Fig. 2 is a side elevation of the coil of Fig. 1 and shows the injector means partly in section. 55

The injectors l5 to l8 inclusive are each connected'as shownin Fig. 2 to the headers I9 and Liquid refrigerant is supplied to the evaporator through the pipe 25 and a portion (herein designated as portion A) of the total amount of refrigerant, supplied to produce the required refrigerating effect in the evaporator; is taken from the liquid line 25 through the pipe 26, the

. valve 21 and the header 20. The other portion (herein designated as portion B) of the total amount of liquid refrigerant required passes from the liquid line 25 through the pipe 35, the float valve 28 into the surge drum 2!! through the pipe 30 into the header Is.

In operation the valve 21 is open far enough to permit the entry into the header 20 of the quantity of refrigerant required to produce the minimum refrigerating effect required from the evaporator coils. The refrigerant required to operate each of the injectors 15 to l8 inclusive is supplied from the header 20, and referring to Fig. 2, it will be noted that this portion A of the liquid refrigerant passes from the header 20 through the nobbles of the injectors. Injector l5 being provided with nozzle 3| and similar nozzles being provided for the other injectors. As long as the valve 21 remains open there is a continuous fiow of refrigerant through the nozzles of the injectors.

In normal operation in order to obtain the required refrigerating effect from the evaporator coil it is desirable to operate the coil in a flooded condition. As shown in the drawing the float valve 28 in connection with the surge drum 29 provides a means of maintaining the evaporator coil in a flooded condition. The portion B of the total refrigerant which is needed to provide refrigerating effects from the coil, in excess of the minimum or basic load of refrigeration, passes through the valve 28, the surge drum 29 and the pipe 30 into the header l9. From the header IS the refrigerant surrounds the nozzles of the injectors l5 to 18 inclusive and by reason of injector action the velocity of the refrigerant which comes through the header I9 is greatly accelerated as it enters the evaporator coil.

Part of the liquid refrigerant is converted into gas in the evaporator coils, and the mixture of gas and liquid refrigerant is carried upward through the coils into the header l4 and enters the surge drum 29 through the-pipe '32. In the surge drum (or liquid trap) thegaseous part of the refrigerant separates from the liquid portion. The gaseous portion is drawn from the surge drum through the suction pipe 33 and passes over to theother part of the refrigerating system to be condensed into liquid and reused. The liquid portion of the refrigerant which separates from the mixture carried into the drum 29, together with any additional liquid refrigerant which enters the drum 29 through the float valve 28, moves downwardly through the pipe 30 into the header l9 and around the injectors IE to l8 in elusive, and is accelerated in entering the heat .from the evaporator coil and break up the films of gas, which resist the transmission of heat into the evaporator as described above, it is desirable to have a recirculation of liquid refrigerant through the coil, the surge drum andthe pipe 30. The maintenance of such a current of liquid refrigerant through the heat absorbing portion of the evaporator circuit is an important feature of my invention. The quantity of refrigerant recirculated through the pipe 30 may be several times as great, during a given period, as the total quantity of refrigerant supplied to the evaporator through the pipe 25 and drawn away through the pipe 33, and which corresponds to the refrigerating effect or load during such period.

The pressures in the several parts of the system will vary with other conditions-in the plant but as an illustrative example the pressure of the liquid in the pipe 25 may be taken at 150 pounds per square inch, the pressure in the header 20 about 100 pounds per square inch and the pressure inthe evaporator coils and headers l4 and I9, will correspond to the temperature desired, but always much less than that existing in the header 20.

It is pointed out that variations in the hook up may be made without departing from the spirit of my invention. Thus, the plain hand operated valve 21 may be replaced by an auto-- matic constant pressure reducing or thermostatic valve if other than manual control is desired at this point. The float valve 28 may be likewise replaced with a different type of control such as a thermally actuated valve.

I claim:

1. In the art of operating a. refrigeration system, the method of feeding an evaporator which comprises the division of the flow of liquid refrigerant supplied to said evaporator from the condensing side of said system into two or more feeds into said evaporator; one or more of said feeds being used to accelerate the circulation of refrigerant through said evaporator and being ,supplied continuously during the operation of said evaporator; and the rest of said feeds being modulating in action, and operating to supply additional refrigerant to the evaporator, as demanded by load conditions and not supplied by the continuous feed connections.

2. The method of feeding liquid refrigerant to the heat absorbing means included in an evaporator circuit which comprises the division of the total quantity of refrigerant required into a portion A and a portion B; continuously injecting said portion A directly into said heat absorbing means; and feeding said portion "3 as required to meet load conditions, in conjunction with said portion A to accelerate the entering velocity of said portion B into said heat absorbing means.

' 3. In a refrigerating system, an evaporator consisting of a plurality of coils, liquid and gas headers connecting said coils, a liquid trap connecting with said headers, an injector in each coil circuit, means for feeding each injector a continuous supply of high pressure liquid refrigerant and means for feeding additional refrigerant into the evaporator to meet any load conditions on the evaporator not met by the refrigerant fed through the injectors.

4. In an evaporator, the combination of a separator drum; a heat absorbing element having a connection with the lower portion of said drum and extending upwardly to a connection with the refrigerant feed arranged to continuously inject liquid refrigerant directly into said heat absorbing element at a point adjacent the bottom thereof, and an independent liquid refrigerant feed to supply additional refrigerant to said drum.

5. In an evaporator, the combination of a separator drum; a heat absorbing element having a connection with the lower part of said drum and extending upwardly to a connection with the upper part of said drum; a suction connection leading from the upper portion of said drum for the withdrawal of vaporized refrigerant; a liquid refrigerant feed arranged to continuously inject liquid refrigerant directly into said heat absorbing element at a point adjacent the bottom thereof, and an independent liquid refrigerant feed under float control to supply additional liquid refrigerant to said drum and maintain a substantially constant liquid level in said heat 7. In an evaporator for a refrigeration plant,

a closed circuit for the re-circulation of liquid refrigerant comprising a gas-liquid separator drum, a heat absorbing element and connections from said drum to said element afloat actuated plant feed of liquid refrigerant to said drum to maintain a substantially constant liquid level in said heat absorbing element; a plant suction line to withdraw vaporized refrigerant from said drum; independent means, to maintain by jet' action, a current of liquid refrigerant in said circuit and a separate plant feed of liquid refrigerant to continuously feed said jet means.

8. In the art of refrigeration, the method of feeding an evaporator circuit, maintained under vaporizing pressure, which comprises the division of the liquefied refrigerant supplied to said evaporator into a feed A and. a feed B; continuously jetting said feed A, under greater pressure into said circuit to impel a current of liquefied refrigerant in said circuit; and supplying liquefied refrigerant to said circuit by said feed B, asrequired by load conditions and not supplied by feed A.

9. In the art of refrigeration, the method of re-circulating liquid refrigerant in a flooded evaporator circuit which comprises the division of the total supply of liquid refrigerant, to be vaporized in said evaporator, into a portion A and a portion B; continuously jetting said portion A into said circuit to impel said recirculation; and feeding said portion B into said circuit as required to maintain flooded operation of said evaporator.'

10. An evaporator for a refrigeration plant, comprising a heat absorbing element, a plant suction connection to said evaporator; a plant feed of liquid refrigerant to said element connected to impel circulation in said element and a separate plant feed of liquid refrigerant to supply additional refrigerant to said evaporator as required by load conditions and not supplied by said first mentioned feed connection.

11. Evaporating apparatus for a refrigeration plant, comprising'a heat absorbing element; a body of liquid refrigerant in said element; a plant suction connection to said apparatus; means to jet liquid refrigerant directly into said element, to impel circulation in said body; a plant connection to supply liquid refrigerant to said means; a separate plant connection to sup-- ply additional liquid refrigerant and maintain said body of liquid refrigerant under varying load conditions on said evaporating apparatus.

12. A method of operating a refrigerating system including anevaporator and a condenser, which consists in passing refrigerant from the condenser to the evaporator through a first path, causing refrigerant passed through said first path toentrain by ejector action other refrigerant withdrawn from the evaporator, whereby the other refrigerant is supplied to the evaporator, and passing other refrigerant from the condenser to the evaporator through a second path to supply load demands not satisfied by refrigerant passed through the first path.

HARRY A. PHILLIPS.

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