Shell and tube heat exchanger having zig-zag tubes

Aug. 15,1950 r. η. tull 2,519,084

SHELL ANDTUBE HEAT EXCHANGER HAVING ZIG-ZAG TUBES

Filed March 13, 1945

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INVENTOR

Robert H. Tull

WITNESSES:

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BY i

ATTORNEY

Patented Aug. 15, 1950 2,519,084

UNITED STATES PATENT OFFICE

2,519,084

SHELL AND TUBE HEAT EXCHANGER HAVING ZIG-ZAG TUBES

Robert H. Tull, Springfield, Mass., assignor, by mesne assignments, to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania

Application March 13,1945, Serial No. 582,507

Claims.

My invention relates to a heat exchanger of the shell and tube type in which one fluid medium flows through tubes enclosed in a shell and another fluid medium flows through the shell in contact with the surfaces of the tubes.

One object of the invention is to provide an improved heat exchanger of the type set forth.

A further object of the invention is to devise a heat exchanger of the type set forth which will give a high rate of heat transfer from one medium to another without unduly prolonging the path of travel of the media or retarding the rate of flow thereof.

A still further object of the invention is to devise a heat exchanger for carrying out the foregoing objects which will be compact, light and inexpensive to produce.

A particular object is to provide a heat exchanger having a shell of minimum bulk, whereby the required space, weight and cost of the shell are reduced.

These and other objects are effected by my invention as will be apparent from the following description and claims taken in connection with the accompanying drawings, forming a part of this application, in which:

Fig. 1 is a view in longitudinal section of a heat exchanger embodying my invention, some of the tubes being omitted;

Fig. 2 is a section on line Π—Π of Fig. 1; and Fig. 3 is a section on line m—HI of Fig. 1.

In the drawings there is shown a shell 10 provided with tube sheets 12 and 14 which, together with the respective adjacent end walls 16 and 18 of the shell form headers 20 and 22 segregated from the remainder of the Interior of the shell. Finned tubes 24 are carried by the tube sheets 12 and 14 and communicate at their respective ends with the headers 20 and 22. An inlet 26 leads to one of the headers 20 and an outlet 28 leads from the other header 22. Thus, a fluid medium admitted through the inlet 26 will flow into the header 20, through the tubes 24, into the header 22 and out through the outlet 28. The interior of the shell 10 between the headers 20 and 22 is provided with an inlet 30 located near the discharge header 22 and an outlet 32 located adjacent the inlet header 20. A fluid medium admitted through the inlet 30 and discharged through the outlet 32 will be in counterflow relation with the medium flowing through the tubes 24.

In order to carry out the invention, the tubes 24 are alternately bent towards the wall and the longitudinal axis of the shell, so as to form, start35 (CL 257—236) tag from the left-hand end of the tubes in Fig. 1, diverging portions 34 and converging portions 36. The interior of the shell, between the tube sheets 12 and 14, is provided with baffles 40 and 42. The 6 baffles 40 and 42 cooperate with each other and with the tube sheets 12 and 14 to provide compartments 46, 48, 50 and 52. The baffles 40 extend inwardly from the wall of the shell and are provided with central openings 54, while the 10 baffles 42 have their peripheries spaced from the wall of the shell so as to form openings 56. As will be seen from Fig. 1, the tube portions 34, at the point of maximum divergence, pass through, and are preferably supported by the baf15 fles 40. The tube portions 36, at the point of maximum convergence, pass through the baffles 42, of which only one is shown in the illustrated embodiment. The baffles 42 may be secured to the wall of the shell, by a spider or the like, not 20 shown, so as to act as a support for the tube portions passing therethrough, or the baffles 42 may be carried by said tube portions.

By this arrangement, a fluid medium, entering the space 46, flowing through the shell, and 25 emerging through the outlet 32, will always flow at an angle to the longitudinal axes of the tubes and substantially parallel to the planes of the fins on the tubes.

Operation

A medium, such as warm liquid refrigerant, is admitted through the inlet tube 26, flows through the tubes 24 and is discharged through the outlet 28. Another medium, such as relatively cool vaporized refrigerant, is admitted through the inlet 30 into the space 46 and into contact with the diverging tube portions 34 in this space. The gas passes between the fins of the tubes and between and around the tubes themselves, and flows through the central opening 54 into the next space 48 where the gas comes into contact with the converging portions 36 of the tubes. From the space 48 the gas flows through the openings 56 into the space 50 and from the space 50 through the opening 54 into the space 52 and out through the outlet 32. The path of flow of the gas through the tubes 24 and from the inlet 30 to the outlet 32 is indicated by the arrows ta Fig. 1.

It will thus be seen that by this arrangement of the tubes and baffles a gas flowing through the interior of the shell must cross and recross the converging and diverging tube portions at an angle to the axis of the tube portions and substantially parallel to the planes of the flns. By this means the gas will have intimate and pro30

3,818,084 longed contact with the surface of the tubes and the fins without material reduction in the velocity of the flow of the gas.

It will also be seen that by this arrangement of the tubes and the baffles, the desired prolonged and intimate contact of the medium flawing through the shell with the medium Sowing through the tubes is obtained without correspondingly increasing the length or diameter of the shell.

It will be particularly noted that by bending the tubes inwardly at the baffle 42 to provide the passage space 56 for flow of fluid, the shell need be only big enough to enclose the baffles 40, thereby reducing the required space, weight and cost of the shell.

The structure described is adapted for use wherever it Is desired to bring two fluid media having a temperature differential into heat exchange relation.

While I have shown my invention in but one form, it will be obvious to those skilled in the art - that it is not so limited, but is susceptible of various changes and modifications without departing from the spirit thereof.