Injector Type Evaporative Heat Exchanger

Abstract

This application discloses an evaporative heat exchanger of the injector type with improvements in mixing and air pumping which are specially adapted to either multiple circular venturies or large circular venturies or both.

Description

This invention relates to evaporative heat exchangers of the injector type and more particularly to spray patterns by which the air pumping and air - water mixing are accomplished efficaciously to transfer a heat load from water to air in venturies of circular section.

While the principle of an injector pump has been long known, see for example U.S. Pat. No. 2,337,983 and while it has also been long known to discharge water in a concurrent flow heat exchanger, see for example British Pat. No. 718,487, these constructions are not sufficiently efficient to compete with counterflow or cross-flow cooling towers or evaporative condensers of modern design.

It is therefore an object of this invention to provide water to air relationships which will result in efficient aspiration of the air and at the same time will result in an efficient transfer of a heat load from the water to the air so that heat dissipation is effectively accomplished.

It is also an object of this invention to provide a cooling tower which is simple to construct and low in cost.

Other objects and advantages of this invention will be apparent upon consideration of the following detailed description of several embodiments thereof in conjunction with the annexed drawings wherein:

FIG. 1 is a view in side elevation of a cooling tower of the injector type in which the air is pumped by a large number of circular section venturies;

FIG. 2 is a view in elevation at the air inlet end of the apparatus of FIG 1;

FIG. 3 is a view in longitudinal section of a modified type of spray in accordance with the present invention, again in connection with a circular section venturi;

FIG. 4 is a view in section taken on the line 4 -- 4 of FIG. 3;

FIG. 5 is a fragmentary view partially in section and partially in elevation of still another type of spray arrangement for use in connection with a circular section venturi;

FIG. 6 is a fragmentary view in section taken on the line 6 -- 6 of FIG. 5;

FIG. 7 is a fragmentary view similar to FIG. 6 but showing a different orientation of the water sprays;

FIG. 8 is a view partly in side elevation and partly in section of still another spray arrangement, again for use in a venturi of circular cross section; and

FIG. 9 is a view in section taken on the line 9 -- 9 of FIG. 8.

In FIG. 1 there is illustrated a horizontal, concurrent flow injector cooling tower having a casing of rectangular cross section defined by sidewalls 10 and 11 and upper and lower walls 12 and 13, respectively. To the left of the casing, as it is viewed in FIG. 1, there is a plate 14 which supports a number of small venturies 15 of circular cross section all oriented in the same direction and positioned close to one another. By using many small venturies, it is possible to achieve the same aspiration capability as could be achieved with a single large one.

By the arrangement of FIGS. 1 and 2 the necessary proportions of the venturies are maintained without requiring an excessive size on the part of any one of them. It can thus be seen that fabrication of the unit as a whole is simple and economical.

To the left of the plate 14 as it is viewed in FIG. 1 there are six pipes 16 parallel to one another and supplied with water from a common manifold 17, see FIG. 2. The pipes 16 are arranged to cross mouths of the venturies 15 diametrically. Centrally registering with the long axis of each venturi 15 is a nozzle 18 supplied with water from a respective one of the pipes 16. Thus, water to have heat extracted from it is delivered to the manifold 17 and is sprayed through the various venturies 15 into a common mixing chamber 19 downstream of the outlets of the venturies. Within the mixing chamber 19 the water and air issuing from the various venturies co-mingle and the water falls, some of it by gravity, into the sump 20, while the rest is stripped out of the airstream by mist eliminators 21 and flows lengthwise of the mist eliminators into the sump 20. The air, free of water droplets, issues from the right end of the cooling tower through turning vanes 22 which direct the air up and away from the apparatus to discourage any tendency of air issuing from the cooling tower to co-mingle with air being drawn into the various venturies 15.

The configuration of the mist eliminators 21 is shown in our prior application Ser. No. 869,798, filed Oct. 27, 1969, the louvers 22 may be as shown in application Ser. No. 144,855, filed May 19, 1971 and the control systems of that application are, of course, applicable here. The blowdown arrangement illustrated is very similar to that shown in application Ser. No. 144,853, filed May 19, 1971.

The blowdown arrangement shown in FIGS. 1 and 2 consists of a gutter 23, the mouth of which is in registry with the ends of the nozzles 18 so that on shutoff the water issuing from the nozzles will be caught in the gutter and drained through conduit 24 to waste. The blowdown is taken from the lowest pipe 16 through a connection 25 to the gutter 23 as in the case of application Ser. No. 144,853, filed May 19, 1971. The pipe 25 is on the opposite side of the gutter 23 from the drain pipe 24 so that the water flowing in the gutter 23 is warm water which may contribute to freeze prevention under winter conditions. The usual make-up water spigot 26 is provided, controlled by a float 27. Cooled water is withdrawn to use through a conduit 28 protected by a screen.

Attention is particularly directed to the fact that the venturies 15 are of circular cross section. Each one consists of a flared mouth portion 29, a throat 30 of reduced cross section, and a flared region of expansion 31 downstream of the throat 30. The sprays issuing from nozzles 18 are of conical configuration and issue from a single nozzle. It is possible, however, to fill the cross section of a circular venturi with sprays or jets from many nozzles, and this may result in much increased efficiency.

If reference is now made to FIGS. 3 and 4, it will be seen that fragments of a circular venturi are shown: an air inlet mouth 32; a throat 33; and downstream of the throat a diverging portion 34 -- all of circular cross section. In or near the mouth portion 32 there is located a circular manifold 35 provided with circumferentially spaced nozzles each of which is so constructed and oriented as to produce a fan-shaped spray on a radius of the circular cross section of the venturi. The way these sprays work together is illustrated in FIG. 4. They function efficiently as air aspirators and air/water mixing with resultant evaporative heat transfer is good. The fan-shaped sprays flow together at about the plane of the throat and effectively seal the same against blowback. Note that each of the sprays issuing from the nozzles 36 has two substantially flat sides where the divergence downstream of the nozzles is minimal and two edges 37, 38, see FIG. 4, which are narrow but have more divergence.

Instead of using a circular manifold as shown in FIGS. 3 and 4, it is possible to use a tree-type manifold system again with flat spray patterns filling the circular cross section of the venturi in various ways such as are illustrated in FIGS. 6 and 7. In FIG. 6, for example, there is a central manifold 39 from which spaced pipes 40 of differing lengths extend in opposite directions so as to cover the circular cross section of the venturi. Nozzles are provided lengthwise of these pipes and the sprays are again of the flat type so positioned with flat sides mutually parallel as substantially to fill the cross section of the throat of the venturi, see FIG. 6. Instead of having the sprays normal to the long axes of pipes 40, they may be diagonal to these pipes as shown in FIG. 7, the diagonal orientation being different in different quadrants of the same venturi throat.

In FIGS. 8 and 9 the effect is about the same as that produced in FIGS. 3 and 4 except that instead of having a manifold with many nozzles there is a single nozzle 41 having circumferentially spaced holes 42 each of which is capable of producing a fan-shaped spray. Again the sprays or jets are disposed with the long axis of the fan shape on radii of the throat of the venturi.

It is to be emphasized that the circular venturies of FIGS. 3 - 9, inclusive, may be used in an assembly such as that shown in FIGS. 1 and 2 or the circular venturi may be so large that a single one may be used as the only pump of an evaporative heat exchanger or combinations of different sizes of different venturies may be used.

While this invention has been illustrated in conjunction with a cooling tower, it is equally applicable to other heat dissipation uses such as indirect evaporative heat exchangers of which a common example is the evaporative condenser.

The invention may be embodied in other specific forms without departing from the spirit or essential characteristics hereof. The embodiment and the modification described are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

Claims

What is claimed is:

1. An evaporative heat exchanger comprising a conduit of circular cross-section having air intake and air exhaust ends, means to spray a plurality of jets of water into said conduit near the air intake end thereof to cause air to be drawn into the conduit and mixed with the water, said jets being substantially flat on opposite sides with diverging edges so as to be in the shape of a fan, said means being so-positioned that the resulting jets are symmetrically disposed in said conduit, said jets each being disposed with the long axis of its fan shape along a different radius of said conduit.