US1923170A - Evaporator - Google Patents

Description

Patented Aug. 22, 1933 louvre!) STATES 1,923,110 nvarona'ron Franklin G. Slagel, Buffalo. N. Y., assl gnor to Fedders Manufacturing Company, Inc., Buffalo, N. Y a Corporation of New York Application May 13, 1929, Serial No. 362,806

Renewed January 10, 1933 BCIaims.

This invention relates to mechanical refrig--' erating systems and more particularly to-evaporators of the flooded type.

Evaporators employed with refrigerating systems of the flooded type usually comprise a header from which tube loops or the equivalent depend, the refrigerant and oil which travel together in cycle through the system being maintained in a body filling the tubes and a portion of the header. The oil is partially or wholly miscible in the refrigerants commonly used, so that oil builds up in the top of the tubes through release of the refrigerant when gasifled. Such' accumulation of free oil in the tubes retards the rise of gasifled refrigerant therethrough, as well as preventing or retarding the flow of liquid refrigerant into the tubes,

so that the transfer of heat through the tubes is inefficient.

An object of this invention is to improve the.

efficiency of evaporators through the above causes, by the provision of means associated therewith to induce circulation in the tubes.

Another object of my invention is to provide an evaporator in which liquid refrigerant is moved to the lower portion of depending tubes by a siphon action.

- A further object of my invention is to improve the heat transfer efficiency of an evaporator of the flooded type in which tubes depend from a header and contain liquid refrigerant and oil. I A further object of my invention is to provide a shield for the open float of an evaporator valve controlling mechanism, so that the liquid particles freed by contact of liquid refrigerant entering the refrigerant body of higher temperature in the evaporator will not travel into the float and be moved into the return tube.

In the accompanying drawing, Fig. 1 is an end view of an evaporator with which my invention is incorporated, portions of the evaporator and tubes being broken away.

Fig. 2 is a side elevation of the evaporator,

a portion ofthe header being broken away.

Fig. 3 is a fragmentary plan view of the float for controlling the valve mechanism in the evaporator.

, Referring now to the drawing by characters of reference, 10 represents a cylindrical evapo- 0 rator header having an integral end 11 and a sealed end 12. Depending from the header are two parallel longitudinal rows of tube loops 13,

the loops extending transversely of the header and having their open ends secured to and in open communication with the header. The ends of the'inner legs 14 of such loops are in a plane below the ends of the outer legs 15', so that circulation is induced downwardly in the inner legs and upwardly in the outer legs. In addition to the loops 13, I provide outer loops 16 which extend longitudinally of the header and exteriorly of the rows of loops, the 'open ends of the loops 16 extending through and being sealed to the header in a plane above the ends of the legs 15.

The header is adapted to contain a body of liquid refrigerant and oil, the upper level of which is indicated at 17, and the open ends of the legs 15 are partially above such level while the ends of the legs 14 and the loops 16 are below the level of the body. It will therefore be seen that a portion of the header and the loops contain liquid refrigerant and oil.

The end 12 of-tlie header supports interior valve mechanism which controls the inlet 18 leading from the condenser of the refrigerating system (not shown). A valve seat member 19 is arranged in the inlet opening 20 and the valve member 21 is arranged to engage the seat member. The valve member is automatically actuated by the open vessel 22 which floats upon i the liquid body in the header. As the liquid level falls the float m'ovesdownwardly permitting the refrigerant and oil in the inlet conduit 23 to open the valve and flow into the header until the body level in the header to a point where the float forces the valve member against the valve seat thus stopping'the inflow; An outlet tube 9 extends into thefloat and oil and gasified refrigerant is drawn by vacuum there from and from the header through the return conduit 24 leading to the compressor (not shown). Y

When liquid refrigerant from the condenser a enters the body 'of warmer liquid refrigerant in. the header there is a turbulence or severe boiling i created which causes liquid refrigerant par-7' ticles to move swiftly into the vapor. space above the inlet. In order to prevent such liquid par- '1 ticles from gathering in the open float, I bend the upper portion of the adjacent float wall outwardly to form a battle or shield 25. Thus movement of such free liquid refrigerant particles into the return conduit is prevented and the frosting thereof from this cause is eliminated. Further the float is notaffected in its normal movement to control the valve, due to the collec- I tion therein of such free liquid particles.--

When the oil is miscible either entirely or partially with v the refrigerant, gasiflcation of the refrigerant in the tube loops frees a pic- 2 portionate quantity of 'oil which will collect in the tube loops and retard or trap refrigerant travel into and gasifled refrigerant travel from the tube loops. With methyl chloride and oil which are wholly miscible together, low tempera'tures change the viscosity of the oilso that it becomes sluggish in the tubeloops when the methyl vaporizes and willretard. or prevent escape of gas or liquid therethrough, thus affect ing materially the heat transfer efllciency of the tube portion of the evaporator. Likewise, with refrigerants such as sulphur dioxide, the oil released by the gasifled refrigerant in the tubes will collect with the same result as with methyl chloride.

In-order to materially reduce such inefliciency through oil binding in the tubes, I provide means through which liquid refrigerant can flow from the header to the bottom of the tubes. To

this end, I provide pipes 30 which extend from the interior of the header to the lowermost portion of the tube loops 13. The pipes 30 are open at both ends and are arranged to extend through the inner legs 14 of the tube loops with the upper ends submerged in the body of liquid in the header and'with the lower ends extending to substantially the center of theloop bends. Irrespective of the oil accumulation in the tubeloops which normally retards escape of refrigerant gas to the vapor space thehea'der, liquid/refrigerant will flow throu the pipes 30 to the bottom of the loops from the liquid body in the header because of the head pressure. A supply of liquid refrigerant to the bottom of the tubes being thus assured, it will vaporize and forceits way up through the legs of the tubes much faster under oil bound conditions than would normally'occur. Other gas trapped in the tubes will also be released with the gas of the refrigerant entering through the pipes, and "as a result the oil in the tubes will'be agitated to a greater extent so thatgas flow is generally more free. Circulation in the tube loops is in this manner assm'ed because the circulation is accelerated and oil retardation is lessened, thus re'sultingin more efilcientheat transfer, from the tube loops.

A sheet brace member extends in intimate metallic contact with andbetween the legs 14, being welded or secured in some manner. Thebracememherterminatesinabottom flange 33 which is secured to the tube loops by a strip of metal 34. This grace member and its relation with the tube loops-provides rigidity and a heat transfer for the loops of the evaporator. r i Various changes can be made in the details of the structure described without departing from the spirit of the invention and the scope of what is claimed.

What I claim is:

1. In an evaporator adapted to contain a body the inlet.

of liquid refrigerant and oil, a header, tube loops depending from the header and in open communication therewith at both ends, .and siphon tube means for inducing circulation of refrig- -erant in a definite directionin the ,tube loops,

said tube means extending through a portion 7 of the tube loop and having its upper end submerged in the liquid in the header.

2. In an evaporator adapted to contain a body of liquid refrigerant and oil, a. header, tube loops depending from the header and in open communication therewith, and an open pipe extending through one leg of the tube loops and into the header. L

3. In an evaporator adapted to contain a body of liquid refrigerant and oil, a'header, U shaped tube loops depending from the header and in open communication therewith, and separate tube means establishing communication between the liquid in the header and the bottom 5. In an evaporator adapted to contain liquid refrigerant and oil, a header, tube loops extending below and in open communication with the header, and a pipe extending throughone leg '01 a tube loop, the end of the pipe being curved 1 downwardly in the header and open at both ends.

6. In an evaporator adapted to contain liquid 15 refrigerant and oil, a header, tube loops arranged in two parallel rows, and pipes extending from the header: through the inner adjacent legs of the parallel tube loops, said pipes being open at both ends and arranged to induce movement of gasifled refrigerant upwardly through the outer legs of the parallel tube loops. 7

7. In an evaporator adapted to contain a body of liquid refrigerant and oil, a header, an open float, and float actuated means for automatically controlling the inlet to'the header to maintain a constant body of liquid therein, said float having a shield extending from the side thereof above the header inlet-.

8 In an evaporatoradapted to contain a body of liquid refrigerant and oil, a header, a refrigerant inlet in theheader wall, valve mechanism controlling the-inlet, and an open float in the header actuating the valve mechanism, the wall of said float adjacent the inlet being turned outwardly at the top in a plane above m G. SLAGEL.

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