US2205292A - Heat exchanger unit - Google Patents

Description

June 18, 1940. A. HOWARD" 2,205,292

' HEAT EXCHANGER UNIT Filed Jan,- 5, 1959 ,,,,u,,,,,,,,,, I v "a 'o, "o 1111 'll/III Ihventort Alah Howard I M by y w a. AMA/ His Attorney.

Patented June 18, 1940 i UNITED STATES PATENT OFFICE HEAT EXCHANGER UNIT Alan Howard, Schenectady, N. Y., assignor to General Electric Company, a corporation of New York Application January 5, 1939,'Serial No. 249,458

9Claims. (Cl. 257-36) Thi invention relates to heat exchangers and in for facilitating the extraction of noncondensparticularly to the air cooled type adaptable for ables condensing elastic fiuid In accordance with the illustrated embodiment 1 cooled heat exchangers usually comprise of this invention, I provide a condenser unit hav- 5 a bank of thin walled tubes arranged in spaced mg plurality of flat rectangular tubes extend 5 apart relationship between upper and lower ing substantially the width of the unit each tube headers. Cooling air is circulated around the being provided with a Partition forming two tubes usually by some blower means for conductsages therein and so arranged as to constitute ing the heat therefrom. The tubes embodied in in effect a continuous passage of progressively such heat exchangers are of many different decreasing cross-sectional area from the elastic 10 shapes and Sizes but for certain purposes it is fluid inlet to the outlet for the noncondensablessmore advantageous to use wide fiat tubes instead For consldemtlon of what I pehgve to be of a relatively greater number of smaller cyllnnovel and.my i f attention dlrected to drical tubes. Because of the relatively lower the followmg descnptlon and the append resistance presented to the air flow, the efilciency ed thereto taken in connection Wlth the accom' 1 of a flat tube heat exchanger is considerably panymg f greater than one with tubes of other shapes in In i drawmg 1 i813 perspectlve i that with a given total tubing surface area a partly m Section h f p elafstlp greater heat transfer is derived for a given fluid condenser embodymg my mventlon;

amount of energy expendedm circulating the Fig. 2 is a cross-sectional view through one of the g0 cooling air. Where the amount of heat to be tubes of the condenser K Shown in 1; F

dissipated is large, such as in condensers for 31s aflfmgmentary viewm perspective lnilstratfmg reducing to condensate the exhaust from elastic certam details of the condense. and Flg? 1s fluid turbines. the total condenser capacity must m crSS .sectiI?a1 View mustra'tmg of necessity be relatively large. Particularly in modlicatilontof "F portab e prime mover plants, such as in locomo- 1 err Hg 0 2 and fg i tlve vehicles, space limitations require that the S s i g ig 1 upper er 0 having overall size of the condenser installation be kept i f as c m 2 e I3 .g header as small as possible which in turn requires that g g Ht g z g i e a large volume of cooling air be circulated thereere D um y o u s are through per square foot of face arca. Considerarranged between the upper. and lower headers ing the large amount of power required by the parallel each otherf and fi g fi cooling air circulating b owers which is frequently apar pm mg pass?'ges or coo ng an .ereof the order of 25% of the power output the between, the tubes being of a width substantially turbine, the matter of condenser efilciency beequal to the wldth of the unit ends of the 35 comes of increasing importance I tubes may be secured in any su1tab1e manner to The use tubes in cond'mer units h the upper and lower headers and it is preferred to ever is complicated thp fact g p22 provide relatively rigid slide plates I5 for stifieni I ng the unit and to re ieve he relatively thin 40, ji i z gzgg ig g z 3:32:3 E 22 tubes of stresses due the weight of the upper 40 or that e maiimum efficiency ye gle I header. For facilitating the heat transfer from a the outer surfaces of the tubes, at luralit of ized from the condenser units, it is necessary that Suitable fins 15 may be provided 1 d i t d, th v l y of theelastic fluid w n t r u h In accordance with my invention, I provide in the tubes be maintained substantially uniform ach tub partition I] extending from the lest the back pressure to the turbine be increased upper end and adjacent one edge of thetube fiby gtrlleduciiilogl in th; rate of flow of the elastic diagonally downwardly to approximately the 111 o s 9 C e center of the lower end as shown best in Fig. 2. It is an object of this invention to provide a The partition strip may be secured in any suit- 0 new heat exchanger having relatively wide flat able manner within the tube. For example, as tubes with means arranged therein for improvshown in Fig. 3, the strip may be preformed mgtthe cofndglrlisingbchatragtigistics tlrilireoflto or cgolged i as to pirovidelgarfllfil sidietfianges I8 is a ur er 0 Jec o s mve ion proan e side ange o t e pa ition s rip vide a new and improvedcondenser having relamay be soldered or welded to the sheet from tively wide fiat tubes with means arranged therewhich the tube will be made and as the sheet i,"

is folded over to form the tube, the opposite side wall will engage with the flange l9 dividing the tube into two longitudinal, tapered passages 20 and 2|. The upper end-of the strip is provided witha flap portion 22 which is adapted to be folded over and secured upon the upper flanges 0f the tube substantially as indicated in Fig. 3 to close the upper end of the passage 2 I. 'The upper end of the passage 20 is substantially equal to the 10 width of the tube and due to the diagonal arrangement of the partition, the passage decreases progressively in cross-sectional area in the downward direction, the lower end of the passage being substantially equal to one-half the 16 size of the upper end. The passage 2| decreases progressively in cross-sectional area in the upward direction from substantially one-half the tube width at the lower end to substantially zero width at the upper end.- It is understood that 20 the angular arrangement of the partition strip may be varied for. dividing the lower end of the.

tube into unequal portions, should it be desirable to compensate for the differences in temperature of the front and rearpassages. The non-condensables are withdrawn from the upper end of the passage 2| through a connection 28 communicating with the conduit 24 to which is connected a'suitable ejector or vacuum pump (not shown).

30 It will be noted that the opening of the tubes in the header I0 is a maximum so that the intake resistance to the elastic fluid passing into the condenser unit is low. As the elastic fluid passes downwardly through the main condensing passages 20 and heat is extracted therefrom, the volume thereof is progressively diminished as condensation takes place. Since the cross-sectional area of the passages progressively vdecreases in the direction of flow, uniform velocity of the elastic fluid flow is maintained'from the upper to the lower ends. The elastic fluid not condensed in the downward pass flows around 5 the lower ends-of the partition strips through the lower header l2 and continues upwardly. through the after-cooler passages 2| which also are of progressively decreasing cross-sectional area in the upward direction and in which passages. the condensation will be completed. It will .be noted that the lower ends of the after-cooler passages .are substantially of the same area as the lower 'ends of the main condensing passages so that all of the elastic fluid emerging from the latter passages may be accommodated in the after-cooler passages without experiencing any appreciable drop in velocity. It is understood that due to the action of the-vacuum pump, ejector, or other device coupled to the conduit 24 for extracting the non-condensables from the condenser unit,

. a suction will be produced on the upper ends of the after-cooler passages so that the vapor not condensed in the downward pass will be drawn -into the second section because of the relatively lower pressure maintained therein. The condensate forming in the after-cooler passages will,

of course, drain downwardly into the lower header. Because of the relatively large opening of the lower end of the after-cooler passages, there will be little likelihood of condensate blocking the end thereof against the admission of non condensed vapor. In effect, the two passages, 20 and 2|, taken 'together perform as a single tube of uniformly and progressively decreasing crosssectional area from the inlet header to the outlet for non-condensables, with means provided for draining the passage of condensate at the'center.

. It will be obvious that the partition may be formed in many ways. The arrangement shown I, is a simple one since only one flange, ll, of the diagonal strip .need be secured to one tube side wall during the manufacture thereof, theflange 5 1 I! being adapted to merely press against the opposite tube side wall. Because of the "low pressure existing in the passage 2| and the relatively higher pressure existing on the opposite side of nections such as 22 thereto for the purpose of so extracting 'noncondensables therefrom. In the modification shown in. Fig. 4, the upper header ,2! is provided with a transversely extending wall 30 providing thereinan auxiliary header chamber 8| for ,the noncondensables from the after- 25 cooler passages. The noncondensables may beextracted from the header chamber 3| through the connection 82 communicating therewith. The

upper end of the partition 33 may be provided with a flap 34 which is adapted to rest against so the wall 20 with spring pressure, which pressure, augmented by the inlet elastic fluid pressure, will maintain the flap substantially tight against the wall 30 throughout the operation of the condenser unit. 85

While I have shown the condenser unit as being made up of wide flat tubes having angularly' arranged partitions therein forming two tapered passages in each tube, it is obvious that two separate tubes may be made up each having a shape T corresponding to the shape of the passages 20 and 2|. Such tubes could be suitably arranged between upper and lower headers and would operate in a manner not unlike the arrangement described in greater detail. The former arrange 5 ment is preferred primarily for manufacturing expediency.

With normal conditions prevailing, it is preferable that the air flow between the tubes be in such a direction as to flrst contact with the after- 50 cooler sections so that completecondnsation of.

the condensable vapors flowing therethrough takes place leaving but dry noncondensables to be extracted. .It is obvious that during periods of abnormallylow temperature of cooling air, 55 the direction of air flow through the condenser unit may be reversed so that it contacts flrst with the section of the tubes carrying the more heated elastic fluid. By doing this, freezing of condensate within the after-cooler passages and g0 Letters Patent of the United States is: 0

1. A surface cooled condenser unit comprising an upper inlet header for elastic fluid to be condensed, a lower outlet header for condensate, a plurality of relatively wide flat tubes communieating between said headers, a partition angu- 75.

larly arranged in each of said tubes forming two passages therein, the first passage having an opening into said upper header of, a width substantially equal to the width of said tube, said first passage decreasing progressively in crosssectional area downwardly, the opening of said first passage into said lower header being substantially one-half of the width of said tube, the second passage having an opening into said lower header of awidth substantially equal to one-half of said tube width and decreasing progressively in cross-sectional area upwardly, the upper end of said second passage being closed, and a connection communicating with the closed upper end of said second passage for withdrawing noncondensables therefrom.

2. An air cooled condenser unit comprising an upper inlet header for elastic fluid to be condensed, a lower outlet header for condensate, a plurality of flat tubes arranged between said headers, said tubes having a width substantially equal to the width of said unit, a partition arranged in each of said tubes extending from the upper end thereof and adjacent one edge substantially to the center of the lower end thereof, said partition forming two tapered passages through said tubes, the first passage communicating between said upper and lower headers, the second passage being closed at the upper end by said partition, and means for withdrawing noncondensables from the closed upper ends of said second passage.

3. An air cooled condenser comprising an upper inlet header for elastic fluid to be condensed,

a lower outlet header for condensate, a plurality of relatively wide flat tubes arranged between said headers, a partition arranged in each of said tubes providing two tapered passages therein, the first passage communicating between said headers and being relatively large and decreasing in cross-sectional area downwardly,'the second passage communicating with said lower header and being relatively smaller than said first passage and decreasing in cross-sectional area upwardly, and means for withdrawing noncondensables from the upper end of said second passage.

4. A surface type condenser comprising an upper inlet header for elasticfluid to be condensed, a lower outlet header for condensate, a plurality of relatively wide flat tubes arranged between said headers, a partition arranged in each of said tubes cooperating therewith to form a main condensing passage communicating between said headers and an after-cooler passage communicating with said lower header, and means communicating with the upper end of said aftercooler passage for extracting noncondensables therefrom. I

5. An air cooled condenser. comprising an inlet header for elastic fluid to be condensed, an outlet header for condensate, a plurality of relatively wide flat tubes arranged between said headers, a header for noncondensables, a partition arranged in each of said tubes cooperating there- I with to form two passages therein, one passage being relatively large and communicating between said headers, the other passage being relatively small and communicating with said lower header and with said header for non-condensables connected thereto at the opposite end thereof.

6. An air cooled condenser comprising an inlet header for elastic fluid to be condensed, an outlet header for condensate, a plurality of relatively wide flat tubes communicating between said headers, a partition substantially longitudinally arranged in each of said tubes cooperating therewith to form two passages therein, said partition substantially closing the upper end of one of said passages and a connection communicating with the closed ends of said passage for withdrawing noncondensables therefrom.

7. A surface type condenser comprising an upper inlet header for elastiefluid to be condensed, a lower outlet header for condensate, a plurality of heat exchanging tubes arranged between said headers, partitioning means arranged in each of said tubes cooperating therewith to form a main condensing passage communicating between said headers and an after-cooler passage communicating with said lower header, means communicating with the upper end of said after-cooler passage for extracting noncondensables therefrom, said partitioning means being angularly arranged with respect to a wall of said tube to maintain substantially uniform the velocity of 30 fluid flow successively through said main condensing passage and said after-cooler passage.

8. A surface cooled condenser comprising an upper inlet header for elastic fluid to be condensed, a lower outlet header for condensate, a 35 plurality of relatively wide flat tubes arranged between said headers, a header for noncondensables, means arranged in each of said tubes dividing each tube into two passages, a first passage communicating between said upper and lower headers, the second passage communicating between said lower header and said header for noncondensables, said dividing means being angularly arranged with respect to a wall of said tube to maintain substantially uniform the velocity of the fluid flow from said inlet to said header for noncondensables.

9. A surface type condenser comprising an upper inlet header for elastic fluid to be condensed, a lower header for accumulating condensate, means for conducting condensate from said lower header, a plurality of heat exchanging tubes arranged between said headers, means arranged in said tubes forming passages of progressively decreasing cross-sectional area from said upper v header to said lower header, saidmeans also forming passages of progressively decreasing cross-sectional area extending upwardly from said lower header, an auxiliary header adjacent said upper inlet header in communication with r;

the upperends of said last mentioned passages for accumulating noncondensables therefrom, and means for extracting noncondensables from said auxiliary header.

ALAN HOWARD.

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