Note: Descriptions are shown in the official language in which they were submitted.
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This invention relates to water distribution
systems and more particularly it concerns novel arrangements
for feeding water to the heat exchange regions of evaporative
heat exchange systems.
Heat exchange systems of the type to which the
present invention is especially suited are shown and
described in U.S. Patents No. 3,1~6,609: No. 3l290,025 and
No. 3,659,623. In those systems, water is supplied continu~
ously to troughs which extend substantially horizontally
along an upper level. The water spills over the upper edges
of the troughs and drops down therefrom through a heat ~ -
exchange region therebelow where it contacts and is cooled
by upwardly moving air. In order to maximize heat transfer
between the downwardly falling water and the upwardly moving
15 air, the water is distributed as widely and as evenly as ~ ~-
possible; and to this end the upper edges of each trough are
notched to define spaced apart spillways through which con-
trolled water flows at defined locations are maintained.
Where the troughs extend over a considerable
distance, i.e., more than twelve feet, the rate of water flow
~- to and out from the various notches along the length of the
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1 troughs becomes c~uite uneven; and unless special precautions
2 are taken, the notched troughs will nol- provide good water
3 distribution. In the past, these special precautions have ~Y
4 included means to assist in the distribution of spillover
water flow along the length of water supply troughs. It has
6 been proposed, for example, to form water distribution
7 channels inside the troughs which separate the longitudinal
8 flows from the exit flows. These channels, which were form-
9 ed of elongated structural elements extending along the
length of the troughs, made the trough structure complicated
11 and expensive. In addition, they tended to clog whenever
12 foreign material was carried in the water passing through
13 them. One quite successful technique for improving flow
14 distribution along water troughs was the provision of a
single horizontal baffle which extended along the length
16 of the trough below the notches. (See for example U. S.
17 Patent No. 3,146,609.) While this horizontal baffle arrange~
18 ment did perform its water distribution function quite well~
19 it did not achieve the structural simplicity and cleanability
obtained with the present invention. '~`~
21 The present invention permits even water distribu-
22 tion from very long troughs with structures which are
23 simpler and more easily cleaned and maintained than those of
24 the prior art.
According to the present invention there is pro-
26 vided a water distribution system comprising a water dis-
27 tribution trough and means for supplying water to the trough
28 from one end and for maintaining the water in the trough at
29 a predetermined level. A series of apertures are formed
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l along the trough a-t a lower leve]; and the head of water
2 above those apertures serves to control the outflow throuyh
3 them irrespective of the longitudinal flow of water alon~
4 the length of the trough. The size of the apertures is so
controlled that the water flowing out from them does not
6 significantly affect the head of water above them. Thus all
7 the apertures are subject to substantially the same head of
8 water and accordingly they each expel water at substantially
9 the same flow rate.
According to one embodiment of the present
ll invention there are provided novel arrangements whereby
12 notched water distribution troughs may be easily recon-
13 structed to provide the improved results described above.
14 These novel arrangements, as described more fully herein-
after/ include elongated strips of inverted U-shape con-
16 figuration, which strips are fitted over each of the upper ~-
17 ed~es of notched troughs to form the notches into apertures
18 located a predetermined distance below the upper edg0s o~
l9 the trough. The strips then serve to contain the head of
water above the thus formed apertures to maintain even
21 distribution of water flow from them.
22 There has thus been outlined rather broadly the
23 more important features of the invention in order that the
24 detailed description thereof that follows may be better
understood, ar~d in order tha~ the present contribution
26 to the art may be better appreciated. There are~ of
27 course, additional features of the invention that will be
28 described hereinafter and which will form the subject of
29 the claims appended hereto. Those skilled in the art will
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l appreciate that the conception upon which this disclosure
2 is based may readily be utilized as a basis for the
3 designing of other arrangements for carrying out the
4 several purposes of the invention. It is important,
therefore, that the claims be regarded as including such
6 equivalent constructions and techniques as do not depart
7 from the spirit and scope of the invention.
8 Plural embodiments of the invention have been
9 chosen for purposes of illustration and description, and
are shown in the accompanying drawings forming a part of
11 the specification, wherein:
12 Fig. 1 is a vertical sectional view taken through
13 a typical evaporative heat exchanger utilizing a water dis-
14 tribution system according to the present invention;
.
Fig. 2 is a view of a water distribution system
16 similar to that shown in Fig. 1 with troughs shown in trans-
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17 verse section but to an enlarged scale;
18 Fig. 3 is a sectional view taken along line 3-3 -
19 of Fig. 2;
Fig. 4 is a fragmentary top plan view of the
21 water distribution system shown in Fig. 3 with parts in
22 section;
23 Fig. 5 is an isometric view of a fragment of a ~
24 typical trough partially cut away; and ~;
Fig. 6 is a view similar to Fig. 5 showing a
26 modified form of water trough according to the present
27 invention.
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1 Referring now -to the drawinys in greater detail,
2 it will be noted that iII the evapora-tive heat exchanger as
3 shown in Fig. 1, a chamber 10 is provided at its upper end :~
4 with a group o~ troughs 11, and at its lower end with a ~:
; 5 sump 12. Each trough, as shown :in Fig~ 5, has triangularly
6 shaped apertures lla formed in its side walls, those in one .
7 side wall being staggered in relation to those of the other :
8 side wall. Water flows out through the apextures lla .
9 in the trough 11 and passes over heat exchanger tubes 13
10 in the form o~ rain or droplets. A centrifugal fan 19, ;~
11 driven by a motor l9a, pumps air through ducting 20 in a
12 slanted wall 34 and this air flows upwardly through the ~: .
13 chamber 10 çountercurrent to the water issuing from the .:
14 troughs 11. The air, after passage through the heat
15 exchanger, passes in between the troughs 11 and throuyh .
-` 16 mist eliminators 21 to atmosphere. The mist eliminator~
17 21 are in the form of baffles covering the cross section~ ~
18 of the upper end of the chamber 10. If a fluid to be ; ~ .
19 cooled or condensed is circulated through the heat
exchanger tubes 13, heat is extracted from it by vapori
21 zation of some of the water spilling from the apertures
22 in the troughs 11. The water thereafter is collected in
~ 23 the sump 12 from which it is re-circulated by a pump 14
24 and a conduit 15 back to the troughs 11. Make-up water
~ 25 enters through a conduit 16 when a valve 17 is opened by
.~ 26 reason of lowering of the float 18, to replace any water
~ 27 evaporated.
; 28 The foregoing is a brief description of an
29 evaporative heat exchanger which is conventional in
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1 structure and operation except for the water distribution
2 system comprised of the troughs 11 having the apertures lla.
3 The invention relatec; specifically to improved
4 arrangements for distributing t:he water over the heat ex-
change surfaces utilizing the clistribution box and trough
6 shown best in Figs. 2-5. For the sake of clarity, only one
7 trough 11 is specifically referred to in Figs. 2 and 4,
8 although it is to be understood that the description
9 applies equally to all the troughs 11. In the improvement,
water is fed through conduit 15 into a distribution box 22
11 at the desired flow rate. While the box 22 may be covered,
12 it is open to atmosphere. An orifice 23 (Figs. 3 and 4) is
13 provided in the wall of the box 22 registering with each
14 trough 11 in order to distribute evenly and to meter the
proper flow to each trough. Each such orifice is of sub-
16 stantially the same size and shape as the trough cross ~
17 section with which it communicates; and it is in alignment ~ -
18 with the trough.
19 Water flow to the troughs is further controlled
by maintaining tlie level of water in the distribution ~ox
21 22 somewhat higher than the upper edges of the troughs 11.
22 It will be noted in Figs. 3 and 5 that the
23 triangularly shaped apertures lla are provided in spaced
24 apart relationship along the length of each trough on each
side thereof near its upper edge. The water flow inside
26 the troughs is maintained such that a finite head (h) of
27 water exists above each of the apertures lla in each trough.
28 This head of water serves to control the flow of water out
29 through the apertures; such flow being substantially
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1 inde,endent of the longitudinal flow velocity of water
2 through the trough. The size of the apertures lla is
3 established such that the outflow of water from them under
4 the influence of the pressure head above them does not ; -
appreciably affect the amount oi- the pressure head. Thus
6 there is obtained a substantially uniform pressure head
7 and consequently uniform flow distribution among the various ;
8 apertures lla of the trough. Also, as can be seen, the size
9 and shape of the apertures lla and the pressure head height
(h) are related such that water passing out through the
11 apertures lla does not project out in streams from the
12 trough but instead merely flows down in thin film config-
13 uration 25 along the outer surfaces of the trough. It has
14 been found tllat a high flow rate without squirting can be
15 ohtained when the apertures have a large perimeter to cross ~
16 section ratio. On the other hand, in designing aperture `
17 configurations with large perimeter to cross section
18 ratios, care must be taken to avoid configurations which
19 t nd to clog. It has been found that an excellent flow
pattern can be obtained with minimal clogging tendency
21 where the apertures lla are of triangular con~iguration
22 and where one of the corners of the triangle is lower than
23 the other two corners.
24 It will be further noted that the bottom of each
trough is rojnded. This permits the water from the aper-
26 tures on one side of the trou~h to run down the outside of
27 the trough and around its bottom so that i~ eventually falls
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28 off toward the opposite side in the form of rain as indi-
29 cated at 26. This provides very good distribution of the
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1 water to the heat exchanger region 13. ~y having the
2 apertures lla staggered from one side of the trough to the
3 other, the water flowing out from the apertures on one side
4 does not interfere with the flow from the apertures on the
other side.
6 By way of example, a trough having a length of
7 18 feet, a height of three inches and a width of one and
8 three eights of an inch can be made to distribute water
9 quite evenly out through apertures in the shape of inverted
triangles where such apertures have a base dimension of
11 three eighths of an inch, a height of three sixteenths of
12 an inch and are spaced two inches apart, at a level seven
13 eighths of an inch below the upper edges of the trough.
14 In such case the water level in the distribution box 22
should be about two and one-half inches above the upper
16 edges of the trough. Under such conditions a flow rate
17 of approximately twenty gallons of water per minute from
18 each trough may be expected.
19 Turning now to Fig. 6, there is shown an arrange-
ment wherein a previously notched water distribution trough
21 can be easily reconstructed in accordance with the present
22 invention. As shown in Fig. 6, a trough 30 is formed
23 with rather deep V-shaped notches 32 along its two upper
24 edges. This configuration is shown in the prior art, for
example in Figs. 3 and 4 of U. S. Patent No. 3,290,025.
26 According ~o the present invention, however, there are
27 provided two elongated strips 34 of inverted U-shaped
28 cross section; and each strip is closely fitted over an
29 associated one of the upper edges o~ the trough. As ca~
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1 be seen in Fig. 6, the heic3ht of each strip 34 is less
2 than the depth of the notches 32 so that when the strips
3 are in place they cooperate with the notches to foxm
4 triangularly shaped apertures 32a in the trough at a dis-
tance below its upper edges corresponding to the height of
6 the strips 34r As shown, this permits the maintenance of
' 7 a predetermined head of water (h) in the trough above the
8 apertures.
9 As with the embodiment of Figs. 2-5, it will be
noted that`in the embodiment of Fig. 6 the apertures along
11 the two sides of the trough are in staggered relationship.
12 This allows the water which exits from the apertures on one
13 side to flow down and spread out in films 36 along the
14 outer trough surface and around the bottom of the trough
without interfering with or being interfered with by the
16 corresponding flows from the opposite side. It is important ~-~
17 for ~ood water distribution that these flows be allowed to
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18 occur along the outer trough surfaces. Because of this the
19 size of the apertures and the height of the pressure head
above them should be such as to prevent squirting or pro-
21 jection of streams of water out from the trough.
22 It will be appreciated from the foregoing that the
23 above described water distribution systems are very simple
24 in construction. Moreover, they contain no internal baffles
and therefore have less tendency to clog than do many of the
26 water distribution troughs of the prior art. Also, the
27 trough arrangements of the present invention are very easily
28 cleaned since all trough surfaces are fully exposed at all
29 times.
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1 Although particular embodiments of the invention
2 are herein disclosed for purposes of explanation, various
3 modifications thereof, after study of this specification,
4 will be apparent to those skilled in the art to which the
invention pertains.
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