US3416775A

US3416775A - Cooling tower packing means

Info

Publication number: US3416775A
Application number: US567011A
Authority: US
Inventors: Szucs Laszlo; Tasnadi Csaba; Linder Istvan
Original assignee: KOMPLEX NAGYBERENDEZESEK EXPOR
Current assignee: KOMPLEX NAGYBERENDEZESEK EXPOR; KOMPLEX NAGYBERENDEZESEK EXPORT-IMPORT VALLALATA
Priority date: 1965-07-28
Filing date: 1966-07-21
Publication date: 1968-12-17
Anticipated expiration: 1985-12-17
Also published as: DE1501393B2; CH460828A; GB1158394A; AT288451B; DE1501393A1

Description

Dec. 17, 1968 szUcs ErAL 3,416,775

COOLING TOWER PACKING MEANS Filed July 21, 1966 2 Sheets-Sheet 1 Dec.17, 1968 L.SZUCS ET AL 3,416,775

COOLING TOWER PACKING MEANS Filed July 2]., 1966 2 Sheets-Sheet 2 United States Patent 3,416,775 COOLING TOWER PACKING MEANS Lszl Sziics, Csaba Tasnzidi, and llstvtin Linder, Budapest, Hungary, assignors to Komplex Nagyberendezesek Export-Import Vallalata, Budapest, Hungary Filed July 21, 1966, Ser. No. 567,011

Claims priority, application Hungary, July 28, 1965,

SU-303 7 Claims. (Cl. 261-112) ABSTRACT OF THE DISCLOSURE A cooling tower having cooling water distribution means which guide a stream of water in a substantially horizontal direction onto a water distributor where it forms a water film which descends due to the gravitational forces. The water distributor includes a plurality of closely spaced wires or bands the upper ends of which may be plain or curved but in any case constitute a descending guide on which the water film is retained. The water is cooled while descending on said water distributor.

The present invention relates to packing means for cooling towers.

The cooling water heated up in various industrial or household appliances (for example air conditioning apparatus) is recooledif reuse is economicin cooling towers. The cooling towers are, for the time being, mostly of the wet type. In such towers the warm cooling water will be brought into intimate contact with the ambient atmosphere, causing one partpractically to -of the cooling water to evaporate while the larger part of the water is recooled to make it suitable again for cooling purposes.

There are numerous well-known designs of cooling towers for bringing about an intimate contact between the ambient atmosphere and the warm cooling water. The most important part of these designs is in every case the so called cooling tower packing, made of wood, plastic, asbestos cement, glass, etc. on the extensive surface of which a heat and mass transfer between the cooling water and the air takes place.

Heat and mass transfer on the cooling tower packings takes place in the following manner: The cooling water is distributed as evenly as possible onto the packing surface. The cooling water streaming downwards under the influence of gravity force, will form a water film on the packing surface. The cooling air is driven by a fan or by means of a natural draft stack, adjacent to the wet surface, in parallel flow or in countercurrent flow to the water flowing downwards or, if necessary, in a so called mixed flow.

The cooling tower packing means in practice have the following disadvantages:

Generally, the known cooling tower packing means require an atomization of the cooling liquid which results in large losses of the cooling liquid due to evaporation.

It is therefore a general object of this invention to provide a cooling tower packing means which does not require atomization of the cooling liquid.

It is another object of this invention to provide a cooling tower packing means which is more compactly constructed than comparable devices of the prior art.

In thermodynamics it has been known for a long time that the break of the boundary layer of the liquid and the use of short surfaces in the flow direction results in advantageous heatand mass-transferring devices.

This recognition has, however, not yet been made use of in designing cooling towers, since no wetting process has been devised which would be suitable for uniformly wetting the required very big number of bands or wires.

It should also be noted that dividing the liquid cooling surface into narrow strips or wires strongly increases by itself the resistance to air flow. The cooling of the cooling liquid can only be improved by bringing about simultaneously a transfer of the heat and mass, what presupposes, however, uniform and complete wetting. The cutting up of the cooling surface accompanied by wrong, uneven or deficient wetting may actually worsen the heat-transfer properties of the surface.

It is therefore another object of the invention to provide a cooling tower design in which the water to be distributed gets from water distribution canals or tubes first into means, e.g. nozzles of large cross section. The water jet leaving the nozzles in a nearly horizontal direction arrives at the upper surface of a water distributor surface and constitutes thereon a Water film. The water distributor surface may be plain or curved, but in any case constitutes a falling surface and the coherent water film spreading on it is retained on the surface by the surface forces between the surface and the water film, as well as by the inertia forces operating on the water film, which counteract the gravity forces.

The cooling tower packing means according to the invention (1) Avoids completely water splitting up into drops thereby avoiding the above mentioned disadvantages and (2) Provides a wetting method which utilizes short surfaces in the stream direction for example bands or wires.

As a result of using the process of the invention, the water does not break up into drops, therefore no drop loss comes about, so that the inconveniences attached thereto are also eliminated. The employed nozzles serve only for producing a nearly horizontal water jet, that is why the water velocity utilized with them can be a low one. Also it permits the use of nozzles having relatively large diameters which reduces the risks of obstructions clogging the nozzles, resulting moreover in requiring a very little pressure head and little pumping work. Finally, the most important effect of the cooling tower packing means of this invention are as follows: the described water distribution manner makes it possible to apply narrow wet surfaces (bands and wires), associated with the said considerable advantages. In order to demonstrate the thermic advantages, arising from breaking of the boundary layer, it should be noted that it was possible to construct in the described manner packing means the volume of whichon supposing invariable cooling and ventilating outputsis ten times less than that of the best known prior art cooling tower packing means.

The invention will be further described, by way of example, with reference to the accompanying drawings, of which:

FIG. 1 is a schematic side view of a packing means in accordance with the invention.

FIGS. 2 to 4 show each a perspective view of a detail of the packing means.

In the equipment manufactured in accordance with the invention the packing surface proper consists of upright or nearly upright bars, for example, wires or bands 4 having a circular, drop shape, rectangular, oval, etc. cross section, the upper ends of which are joined from below at their upper extremities, either in a direct manner or through a very small gap, to a sloping water distributor surface 2. The air flows among the bars, wires or bands 4, in a perpendicular or nearly perpendicular direction with respect thereto (as indicated by the arrows 5). Due to this arrangement the boundary layers on the surface elements 4 are very small and the heatand mass-transfer coefficients are very high (7 to 10 times that of the known packings). On the point 6 where the bars, wires or bands 4 are joined to the distributor surface 2 a deflector means 13 with a deflector surface 7 is arranged. This deflector means 13 may be fastened either to the wire 4 or to the distributor surface 2 and forms at any rate a surface in the way of the water film 3 streaming on the distributor surface 2, against which it will impinge. In this way part of the water will be driven onto the wire or band 4. In order to assure optimum operating conditions for the deflector surface 7 the gap between the distributor surface 2 and the deflector means 13 or between the deflector means 13 and the band 4 must not be longer than 3 mm. In case the gap is larger, the water will not be separated from the distributor surface 2 or else the separated water will be sprinkled and so will not arrive dropless at the surface of the descending elements 4. The water mass driven onto the band or wire 4, under influence of the surface stress flows round the wire 4 and forms on its surface a coherent film and this surface enclosing water film streams downwards. The junction 6 of the wire 4 and surface 2 does not break up the coherence of the water film S-because, due to the influence of the surface stress, the water film continuity is maintained while the water flows over the wire.

For .safe wetting of the wires 4 it is of great importance to form a suitable junction 6 of the Wires 4 and the distributor surface 2.

The cooling water film 3 tends to maintain its impulse while it streams downwardly on the inclined distributor surface 2 and therefore tends to evade the wires 4 and to flow on to the surface 2, thus avoiding the wires 4. In order to guarantee perfect, even and safe wetting of the wires 4, at the junction 6 of the wires 4 and the distributor surface 2, a deflector surface 7 is formed. These deflector surfaces 7 will face the flow direction 12 of the cooling water film 3, and seen from the flow direction 12 of the cooling water film 3, to the surface 7 are concave, or in a special case, flat. If the deflector surafce 7 is convex seen from the flow direction 12, the water flows on along the distributor surface 2 and the deflector means 13 does not fulfill its task. The deflector surface 7 may be shaped so as to fit tangentially to, or communicate with a blunt angle, and in a special embodiment with a right angle, with the distributor surface 2. These arrangements ensure the water flowing on to the deflector surface 7 to turn into the direction of the bar-constituent. Without the aforedescribed arrangements the separation will become uncertain or cease, the water will flow on beyond the deflector means 13 and will not arrive on the bar surfaces. The deflector surface 7 is joined preferably tangentially to the distribution surface 2. The deflector surface 7 may also be formed by an inclined surface which is joined to the wires 4 at a blunt angle. With this arrangement the separated water arrives on the surface of the bars free of drops, thereby constituting a continuous Water-film. The choice of the angles joining the

surfaces

2 and 7 ensures a continuous water-film even in thec ase when a gap is left between the deflector means 13 and the distributor surface 2.

The absolute values of the sizes of the cross sections of the bars 4, which form the packing means, can only be determined in each case separately by economy calculations depending on the packing substance, the power prices, the layout costs, etc. Thus it is, as far as it concerns the invention, immaterial whether the bar is in certain special cases a wire as thin as a hair or a bar of larger diameter, and whether the band is a few tenths of millimeters thick or a strip of a few millimeters in width or a large plain sheet.

FIGURE 2 illustrates an enlarged deflector element 13 for the case when the wire 4 has a circular cross section, and the deflector surface 7, if seen from the on-streaming direction 12 of the cooling water film, is concave. The deflector surface 7 fits to the distributor surface 2 tightly and tangentially, while also tightly and tangentially joining the surface of wire 4.

FIGURE 3 illustrates another possible embodiment of the deflector means 13 where the wire 4 has a rectangular cross section and the deflector surface 7 is plain and joins to the distributor surface 2 at a blunt angle 8 with a gap 9, which is less than 3 millimeters. The deflector surface 7 also joins, at a blunt angle 10 and adjacent to the surface of the wire 4, the main body of the wire 4.

FIGURE 4 illustrates still another possible embodiment of the deflector means 13, where the wire 4 has a rectangular cross section and the deflector surface 7 is plain and joins tight to the distributor surface 2 at right angle 8 while being parallel to the wires 4, as well as being spaced therefrom with gap 11 which is less than 3 millimeters in width.

Although our invention has been illustrated and described with reference to the preferred embodiments thereof, we wish to have it understood that it is in no way limited to the details of such embodiments but is capable of numerous modifications within the scope of the appended claims.

What we claim is:

1. Cooling tower packing means comprising, in combination, a sloping water distributor surface, means for supplying water to said water distributor surface, upright bars joining said water distributor surface from below, and deflector means at the upper extremities of said bars for conducting water from said water distributor surface to said bars.

2. A cooling tower packing means as claimed in claim 1, wherein said deflector means is spaced from said water distributor surface by a maximum distance of 3 millimeters and is joined to its associated bar.

3. A cooling tower packing means as claimed in claim 1, wherein said deflector means is joined to said water distributor surface and it is spaced from its associated bar by a maximum distance of 3 millimeters.

4. A cooling tower packing means comprising, in combination, a sloping water distributor surface, means for supplying water to said water distributor surface, upright bars joining said water distributor surface from below, and deflector means having a nonconvex deflector surface arranged at the upper extremities of said bars for conducting water from said water distributor surface to said bars.

5. A cooling tower packing means as claimed in claim 4, wherein said deflector surface is joined at an obtuse angle to said water distributor surface.

6. A cooling tower packing means as claimed in claim 5, wherein said deflector surface is joined tangentially to said bar.

7. A cooling tower packing means as claimed in claim 5, wherein said deflector surface is joined with an obtuse angle to said bar.

References Cited UNITED STATES PATENTS FOREIGN PATENTS 3/1951 Austria. 7/ 1934 France.

HARRY B. THORNTON, Primary Examiner.

TIM R. MILES, Assistant Examiner.