US2285225A - Flat tube condenser - Google Patents

Description

June 2, 1942. R. H. NORRIS 2,285,225

FLAT TUBE CONDENSER Filed Jan. 16, 1941 9" l I 4 Fl .2. I I4 3 I9 /L m A n u a n a w \I 20 I3 Z! I; 0

Inventor:

Rollin H. Norris,

' His Attorn ey- Patented June 2, 1942 1 FLATTUBE CONDENSER Itollin H. Norris, Schenectady, N. Y., assignor to General Electric New York Company, a. corporation of Application January 16, 1941. Serial No. 374,726

(or. 257-128) g s 6 Claims.

. V The present invention relates to flat tube condensers or surface type heat exchangers such as may be used in elastic fluid power plants for condensing elastic fluid discharged from turbines or other consumers of elastic fluid. The inventionv is of particular significance in connection with locomotive steam power plants in which the condensation is effected in a row or rows of finned, flat tubes by means ofa stream of air forced through the channels defined between the tubes. Elastic fluid conducted to condensers for condensation ordinarily contains a certain amount of non-condensables in the form of air or other gases. 1 These non-condensables when permitted to accumulate in the condenser tubes reduce appreciably the heat transfer through the tubes and accordingly the efficiency and economy of the condenser. Excessive accumulation of .non-condensables may occur if the velocity of :the elastic fluid through the condenser tubes is permitted to drop towards the outlet of the tubes. :One object of my invention is to provide an improved construction and arrangement of fiat tube condensers whereby effective condensation of elastic fluid is obtained along the entire length of each tube. a t

For a consideration of what I believe to .be novel and my invention, attention is directed to the following description and the claims append- .ed thereto in connection with the accompanying tially parallel with each other and closely spaced and connected by. short, rounded side walls l3 and M. The Width of the tubesin the direction of airflow indicated by an arrow may be" of the order of one-eighth of the length of the tubes and in the present example the width of the tubes is of the order of more than ten times the spacing between the front and rear walls ll, I2.

The upper or inlet ends of the tubes are con.- nected to an upper header l with an inlet conduit I'B for receiving elastic fluid to be condensed. The lower or outlet ends of the tubes are secured toan end plate H with a row of the perforations .is received in a lower header |9 with a condensate drain conduit 20. In the present example there is one perforation l8 for each tube 10 and this perforation is substantially spaced from the vertical centerline of the tube and arranged near the side wall l 3-of the tube y During operation, elastic fluid on its path from the upper or inlet ends to the lower or outlet ends of the tubes is gradually condensed by the cooling effect of a stream of air-or like cooling fluid flowing through the passages formed between adjacent tubes. Due to this gradual condensation the relative amount of air and other non-condensables increases gradually towards the outlet end of each tube. If the Velocity of flow is permitted to drop substantially towards the outlet end of the tubes the non-condensables .accumulate near the outlet end and this accumulation of non-condensables affects considerably theheat transfer through the end portions near the outlets of the tubes.

IIn accordance-with my invention I provide means in each tube to form a plurality of parallel-connected channels near the outlet of each tube with thecross-sectional area of each channel gradually decreasing towards the outlet. In the arrangement of Figs. 1 and 2 this is accomplished bythe provision of a plurality of V- shaped baflies 2| made from flat strips of ma-. terial and secured to the front and rear walls H and I2 of the tubes. These baflles define a pluirality of channels 22 parallel-connected at, their upper and lower ends and gradually decreasing in cross-section towards their lower ends. The

channels are provided in the lower or outlet por- '23 extends substantially horizontally from the perforations lfl for discharging condensate from side wall 13 towards an intermediate portion of the front and rear walls H, 12, spaced from the other side wall l4. With the baffles 23 each tube forms two series-connected passages 24 and 25. The passage 24 receives fluid from the channels 22 and gradually increases in cross-section in the direction of flow so as to maintain substantially constant the velocity of flow through the passage 24. The passage 25 decreases slightly in the direction of flow towards the perforation I8.

In place of the V-shaped baffles shown in Figs. 1 and 2 a similar result may be attained by the provision of an arrangement as shown in the modification of Fig. 3 in which a tube 28 provided with a fin 29 has front and rear walls 30, 3| provided with indentations 32 and 33. These indentations may be V-shaped and extend over a length of about one-fifth of the entire length of the tube near the outlet thereof. The indented portions of the front and rear walls may engage each other although this is not essential.

My invention, as stated above, is specially significant in connection with locomotive steam power plants in that the'condensation may be carried out in a single row of flat tubes. The use of one row of condenser tubes measured in the direction of airflow assures uniform condensation in all the tubes. In case separate tapered channels are formed in the manner shown in Figs. 1 and 2 it is important to avoid blocking-off by the bafiies of an excessive area of the tube wall because this might seriously reduce the heat transfer from the outside of the blockedofl region. In addition, it is important to arrange the baflles so that condensate may drain freely from all parts of each tube towards the outlet thereof.

Having described the method of operation of my invention, together with the apparatus which I now consider to represent the best embodiment thereof, I desire to have it understood that the apparatus shown is only illustrative and that the invention may be carried out by other means.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. Flat tube condenser comprising a row of flat tubes, a header for receiving elastic fluid connected to the upper ends of the tubes, and another header for receiving condensate connected to the lower ends of the tubes, each tube having an inlet portion connected to the upper header forming a passage of uniform cross section and an outlet portion near the lower header forming a plurality of parallel-connected channels, each channel decreasing in cross-section towards the lower header to maintain substantially constant velocity of the fluid flowing therethrough.

2. Flat tube condenser comprising a row of flat tubes having inlet and outlet ends, a header for receiving elastic fluid to be condensed and connected to the inlet ends of the tubes and a header for receiving condensate connected to the outlet ends of the tubes, each tube having an inlet portion forming a passage of substantially uniform cross section and a portion near the outlet end with a plurality of baffles to form a plurality of separate parallel-connected channels decreasing in cross-section towards the outlet ends.

3. Flat tube condenser comprising a single row of flat tubes having inlet and outlet ends, a

header for conducting elastic fluid to the inlet ends of the tubes, an end plate secured to the outlet ends of the tubes and having a separate opening for each tube, and a header secured to the end plate for receiving condensate through the openings, the outlet end portion of each tube forming a plurality of parallel-connected channels with a cross-sectional area gradually decreasing towards the outlet.

4. Flat tube condenser comprising a row of flat tubes, an upper header for receiving elastic fluid connected to the upper ends of the tubes, an end plate secured to the lower ends of the tubes andhaving a row of openings for discharging condensate from the tubes, the openings being considerably spaced from the centerlines of the tubes, each tube having a portion near the end plate forming a plurality of parallel-connected channels decreasing in cross-section in the directon of flow and another portion between the first named portion and the end plate forming a passage for receiving fluid discharged from the channels, said passage having a varying cross-section to assure substantially constant velocity of flow of fluid from said channels towards the discharge openmgs.

5. A flat tube for a condenser having substantially parallel closely-spaced front and rear walls, an end portion of the tube over a length of the order of one-fifth of the entire length of the tube including a plurality of flat strips forming V-shaped bafiles secured to the front and rear walls of the tube to form a plurality of parallel- ROLLIN H. NORRIS.

Images