HK1066499B

HK1066499B - Evaporative cooler

Info

Publication number: HK1066499B
Application number: HK04109334.2A
Authority: HK
Inventors: 理查德．P．梅里尔; 乔治．R．施赖弗
Original assignee: 艾威普科国际公司
Priority date: 2001-06-20
Filing date: 2002-06-03
Publication date: 2006-06-09

Description

Evaporative cooler

Technical Field

The present invention relates generally to evaporative coolers and more particularly to heat exchange apparatus such as closed loop cooling towers or evaporative condensers.

Background

Evaporative coolers are widely used equipment comprising a direct heat exchange section and an indirect heat exchange section. An evaporative liquid, typically water, is distributed in the indirect heat exchange section. The indirect heat exchange section is usually composed of a set of mutually independent closed circuits or loops for conveying a fluid stream to be heat-transferred, i.e. to be cooled, and if the evaporative cooler is used as a closed-loop cooling tower or evaporative condenser, heat is indirectly transferred from the fluid stream, which heat rapidly heats the liquid coating film of the evaporative liquid flowing through the closed circuits, thereby warming the evaporative liquid. Typically, these closed circuits are an assembly of pipes or coils, which may or may not be circular in cross-section, such as is disclosed in U.S. patent No. 4755331, the contents of which are incorporated herein by reference.

In the direct evaporative heat exchange section, the heat absorbed by the evaporative liquid is transferred directly to the air stream. In the direct evaporative heat exchange section, the evaporative liquid is directed onto a solid surface area, also commonly referred to as the wet fill pack (fill), where a small portion of the liquid evaporates, cooling the remaining liquid portion. The packing set layer includes a variety of structures, such as wood slats, corrugated metal sheets, laminated molded plastic sheets, and the like. One particular filler group layer is disclosed, for example, in U.S. patent No. 5124087, the contents of which are incorporated herein by reference.

Over the past 50 years, there have been numerous technical improvements to wet pack layers. Wet packed layers have been developed into highly efficient multi-ply plastic sheets that are much more efficient than the older splash packed layers and that reduce the pressure drop and allow the temperature of the evaporative liquid to approach the wet bulb temperature as it leaves the packed layer.

In the early days of the development of the wet packing set of cooling towers, the best technique was to simply stack the wooden battens, which would allow water to splash and disturb the air flowing through. The function of the wet filler group layer is as follows: as much water surface area as possible is exposed to as much airflow as possible and for as long a time as possible with minimal resistance to airflow. Early cooling tower wet packing sets were very inefficient in this process. At that time, it was common practice to place a heat transfer coil in the air and water stream without using any cooling tower wet pack layers. The advantages of wet packing sets are extremely limited relative to the geometry of the piping that is located in the air stream and over which water is splashed.

More and more inventions have been developed for the development of wet packing sets that combine packing sets with coils to accomplish this type of cooling. As the properties of the filler group improved, the inventors discovered the benefits that could be obtained by combining the two media. However, the prior art emphasizes the importance of having air flow through (and past) the coil assembly coupled to the wet packing set layers. In any case, the prior art still has the coil through which the air flows. Research efforts over the years have been directed to providing a method of facilitating or improving the flow of air through heat transfer coils. Even with these improvements in coil design, the amount of water available to the coil is still limited and does not block the flow of air until sprayed onto the coil. In some cases, the air flow is arranged parallel to the direction of the water flow so that the air flow is ideally through the coil.

A typical evaporative cooler includes a coil of indirect heat exchanger as part of a packing set layer, which is either interspersed in the packing set layer of the direct heat exchange section as disclosed in U.S. patent No. 3012416; or in separate heat exchange sections as disclosed in U.S. patent nos. 5435382, 4683101, 5724828, and 4112027, and both the direct and indirect heat exchange sections rely, at least in part, on the flow of a large volume of air to facilitate direct evaporative heat exchange in both heat exchange sections.

The evaporative liquid is typically circulated through the evaporative cooler so that it flows in a continuous loop from the indirect cooling zone to the direct cooling zone and then back to the indirect cooling zone, and in the process adds some liquid to compensate for the amount of liquid that has evaporated.

Disclosure of Invention

The present invention has investigated the advantages of the various improvements of the prior art and has combined these advantages in a unique way to achieve unexpected surprising results.

To this end, the invention proposes an evaporative cooler comprising: a liquid dispenser; an evaporation body having a surface and occupying a first planar area for receiving liquid from the liquid distributor and flowing over the surface and substantially throughout the first planar area; a ventilation device for generating an air flow; a surface of the evaporation body is arranged in the air flow, which air flow causes evaporation of a small part of the liquid received by the evaporation body, whereby the remaining liquid part is cooled; a heat transfer working fluid conduit disposed substantially outside of said gas stream, the conduit having a second planar area that is smaller in size than said first planar area; said heat transfer working fluid line having a surface arranged to receive substantially all of the cooled liquid portion from said evaporative body in heat transfer relation, thereby heating said liquid portion; a flow accelerator disposed between the evaporation body and the heat transfer working fluid line for increasing a flow velocity of the unevaporated liquid to at least about 2.9 meters per second prior to contacting the heat transfer working fluid line; a liquid collector disposed between the evaporation body and the heat transfer working fluid conduit so as to collect the unevaporated liquid flowing from the first planar area substantially to the second planar area; a liquid collector arranged to receive substantially all of the heated liquid portion from the heat transfer working fluid line; and a liquid circulation mechanism arranged to return said heated liquid portion to said liquid distributor.

Preferably, the liquid collector comprises an open pan.

Preferably, the liquid collector comprises a conduit.

Preferably, the liquid circulation mechanism comprises a pump.

Preferably, the liquid distributor comprises at least one nozzle.

Preferably, the liquid distributor comprises a porous liquid channel.

Preferably, the evaporative body includes a wet filler layer set.

Preferably, the evaporation body comprises a stack of vertically oriented thin layers of material.

Preferably, the sheet material is non-planar.

Preferably, the ventilation means comprises a fan.

Preferably, the ventilation means comprises a blower.

Preferably, the heat transfer working fluid circuit comprises at least one coil.

Preferably, the heat transfer working fluid line is located entirely outside of the gas stream.

Preferably, the heat transfer working fluid line is disposed directly below the evaporation body.

Preferably, the heat transfer working fluid conduit is located laterally of the evaporator.

Preferably, the liquid collector includes an inclined wall surface extending into a space between the evaporation body and the heat transfer working fluid pipe.

Preferably, the fluid collector includes a fluid collector configured to receive substantially all of the unevaporated fluid from the evaporative body and a fluid distributor configured to distribute substantially all of the unevaporated fluid to the heat transfer working fluid circuit at the same rate at which the fluid is received from the evaporative body.

Preferably, the ventilation means is arranged to generate the air flow in a direction counter to the direction of flow of the liquid across the surface of the evaporator.

Preferably, the ventilation means is arranged to generate the air flow in a direction substantially perpendicular to the direction of flow of the liquid across the evaporator surface.

Preferably, the second planar area is about 20% to about 90% of the first planar area.

Preferably, the second planar area is about 25% to 80% of the first planar area.

Preferably, the second planar area is about 40% to about 70% of the first planar area.

Preferably, said heat transfer working fluid circuit comprises a coil assembly having an inlet located below an outlet thereof, whereby liquid working fluid entering from said inlet will flow upwardly through said coil assembly and exchange thermal energy with said cooled liquid portion through the wall of said coil, wherein the cooled liquid portion flows downwardly thereby cooling said liquid working fluid, and said liquid working fluid exits said coil through said outlet.

Preferably, said heat transfer working fluid circuit comprises a coil assembly having an inlet located above an outlet thereof, whereby gaseous working fluid entering from said inlet will flow downwardly through said coil assembly and exchange thermal energy with said cooled liquid portion through a wall of said coil, wherein the cooled liquid portion flows downwardly, thereby condensing said gaseous working fluid into a liquid, and said working fluid flows out of said coil through said outlet.

Preferably, said flow accelerator comprises a vertical space between said heat transfer working fluid conduit and said evaporator, having a dimension of at least 0.61 meters.

Preferably, the fluid collector includes a vertical space between the heat transfer working fluid conduit and the evaporation body, and the air inlet of the ventilation device is disposed in the space between the evaporation body and the heat transfer working fluid conduit, so that the air flow from the air inlet to the ventilation device concentrates the unevaporated fluid flowing from the first region substantially to the second region while the unevaporated fluid drips between the evaporation body and the heat transfer working fluid conduit.

In another aspect, the present invention also provides an evaporative cooler comprising: a liquid dispenser; an evaporation body having a surface for receiving liquid from the liquid distributor; -ventilation means arranged to generate an air flow over the surface of said evaporation body, said air flow causing a small portion of said liquid received by said evaporation body to evaporate, thereby cooling the remaining portion of said liquid; a heat transfer working fluid conduit arranged to receive substantially all of the cooled liquid portion from the evaporative body in heat transfer relation, thereby heating the remaining liquid portion; a flow accelerator located between the evaporation body and the heat transfer working fluid line for accelerating the flow velocity of the cooled liquid to at least about 2.9 meters per second prior to contacting the heat transfer working fluid line surface; a liquid collector arranged to receive substantially all of the heated liquid portion from the surface of the heat transfer working fluid line; a liquid circulation mechanism; and liquid passages connecting the liquid container, the circulation mechanism, and the liquid distributor.

Preferably, the flow accelerator includes an open plenum between the evaporator and the heat transfer working fluid line.

Preferably, the flow accelerator comprises a pump and nozzle system.

Preferably, the heat transfer working fluid conduit is located substantially outside of the gas stream.

Preferably, said evaporator body has a surface and occupies a first planar area for receiving liquid from said liquid distributor and flowing over said surface and substantially over said first planar area, said heat transfer working fluid circuit having a second planar area that is smaller in size than said first planar area; and a liquid collector disposed between said evaporation body and said heat transfer working fluid conduit for collecting said unevaporated liquid flowing from said first planar area to said second planar area.

In yet another aspect, the present invention also provides an evaporative cooler comprising: a liquid dispenser; an evaporation body for receiving liquid from the liquid distributor; ventilation means arranged to generate an airflow through said evaporation body, said airflow causing a small portion of said liquid received by said evaporation body to evaporate, thereby cooling the remaining portion of said liquid; heat transfer working fluid conduits disposed at spaced apart locations downwardly relative to said evaporation body such that said cooled liquid portion flowing from said evaporation body is accelerated by gravity at a flow rate of at least about 2.9 meters per second prior to contacting a surface of said heat transfer working fluid conduits; a liquid collector arranged to receive substantially all liquid from the surface of the heat transfer working fluid line; a liquid circulation mechanism; and liquid lines connecting the liquid container, the circulation mechanism, and the liquid distributor.

Preferably, the heat transfer working fluid line is located substantially outside the gas stream.

Preferably, said evaporator body has a surface and occupies a first planar area for receiving liquid from said liquid distributor and flowing over said surface and substantially over said first planar area, said heat transfer working fluid circuit having a second planar area that is smaller in size than said first planar area; and a liquid collector disposed between the evaporation body and the heat transfer working fluid conduit to collect the cooled liquid flowing from the first planar area to the second planar area.

In yet another aspect, the present invention also provides a method for cooling a working fluid, comprising the steps of: dispensing a liquid onto a surface of an evaporation body; blowing air over the surface of the evaporation body to evaporate a small portion of the liquid, thereby cooling the remaining portion of the liquid; accelerating the cooled portion of the liquid to a velocity of at least about 2.9 meters per second and directing the liquid to a surface of a heat transfer working fluid circuit; flowing a working fluid through said heat transfer working fluid line to transfer heat from said working fluid to said cooled portion of said liquid to heat said portion of said liquid; collecting heated liquid from said outer surface of said heat transfer working fluid conduit and recycling said warmed liquid portion back to said evaporator.

Preferably, the heat transfer working fluid circuit is maintained in an area where there is substantially no airflow.

In another aspect, the present invention provides an evaporative cooler, comprising: a liquid dispenser; an evaporation body having a surface and occupying a first planar area for receiving liquid from said liquid distributor and flowing over said surface and substantially throughout said first planar area; a ventilation device for generating an air flow; a surface of the evaporation body is arranged in the air flow, which air flow causes evaporation of a small part of the liquid received by the evaporation body, whereby the remaining liquid part is cooled; a heat transfer working fluid conduit disposed substantially outside of said gas stream, the conduit having a second planar area that is smaller in size than said first planar area; said heat transfer working fluid line having a surface arranged to receive substantially all of the cooled liquid portion from said evaporative body in heat transfer relation, thereby heating said liquid portion; a fluid collector disposed between said evaporation body and a planar region of said heat transfer working fluid, said fluid collector comprising a vertical space between said heat transfer working fluid conduit and said evaporation body, an air inlet of said air moving device being disposed in said space between said evaporation body and said heat transfer working fluid conduit, whereby, while said unevaporated fluid drips between said evaporation body and said heat transfer working fluid conduit, an air flow from said air inlet to said air moving device is configured to collect said unevaporated fluid flowing from said first region substantially to said second region; a liquid collector arranged to receive substantially all of the heated liquid portion from the heat transfer working fluid line; and a liquid circulation mechanism arranged to return said heated liquid portion to said liquid distributor.

Preferably, a flow accelerator is further included and disposed between the evaporative body and the heat transfer working fluid line, the flow accelerator increasing the flow velocity of the non-evaporative liquid to at least about 2.9 meters per second prior to contacting the heat transfer working fluid line.

In another aspect, the present invention provides an evaporative cooler comprising: a liquid dispenser; an evaporation body having a surface and comprising a stack of vertically oriented sheets of material, wherein said sheets of material are non-planar and occupy a first planar area for receiving liquid from said liquid distributor and flowing over said surface and substantially throughout said first planar area; a ventilation device for generating an air flow; a surface of the evaporation body is arranged in the air flow, which air flow causes evaporation of a small part of the liquid received by the evaporation body, whereby the remaining liquid part is cooled; a heat transfer working fluid conduit disposed substantially outside of said gas stream, the conduit having a second planar area that is smaller in size than said first planar area; said heat transfer working fluid line having a surface arranged to receive substantially all of the cooled liquid portion from said evaporative body in heat transfer relation, thereby heating said liquid portion; a flow accelerator disposed between the evaporation body and the heat transfer working fluid line for increasing a flow velocity of the unevaporated liquid; a liquid collector disposed between the evaporation body and the heat transfer working fluid conduit so as to collect the unevaporated liquid flowing from the first planar area substantially to the second planar area; a liquid collector arranged to receive substantially all of the heated liquid portion from the heat transfer working fluid line; and a liquid circulation mechanism arranged to return said heated liquid portion to said liquid distributor.

Preferably, the flow accelerator increases the flow velocity of the non-vaporized liquid to at least about 2.9 meters per second prior to contacting the heat transfer working fluid line.

In yet another aspect, the present invention provides an evaporative cooler comprising: a liquid dispenser;

an evaporation body having a surface and comprising a stack of vertically oriented sheets of material, wherein said sheets of material are non-planar and occupy a first planar area for receiving liquid from said liquid distributor and flowing over said surface and substantially throughout said first planar area; a ventilation device for generating an air flow; a surface of the evaporation body is arranged in the air flow, which air flow causes evaporation of a small part of the liquid received by the evaporation body, whereby the remaining liquid part is cooled; a heat transfer working fluid conduit disposed substantially outside of said gas stream, the conduit having a second planar area that is smaller in size than said first planar area; said heat transfer working fluid line having a surface arranged to receive substantially all of the cooled liquid portion from said evaporative body in heat transfer relation, thereby heating said liquid portion; a flow accelerator disposed between the evaporation body and the heat transfer working fluid line for increasing a flow velocity of the unevaporated liquid to at least about 2.9 meters per second prior to contacting the heat transfer working fluid line; a fluid collector disposed between said evaporation body and a planar region of said heat transfer working fluid, said fluid collector comprising a vertical space between said heat transfer working fluid conduit and said evaporation body, an air inlet of said air moving device being disposed in said space between said evaporation body and said heat transfer working fluid conduit, whereby, while said unevaporated fluid drips between said evaporation body and said heat transfer working fluid conduit, an air flow from said air inlet to said air moving device is configured to collect said unevaporated fluid flowing from said first region substantially to said second region; a liquid collector arranged to receive substantially all of the heated liquid portion from the heat transfer working fluid line; and a liquid circulation mechanism arranged to return said heated liquid portion to said liquid distributor.

In another aspect, the present invention provides an evaporative cooler comprising: a liquid dispenser;

an evaporation body having a surface and occupying a first planar area for receiving liquid from said liquid distributor and flowing over said surface and substantially throughout said first planar area; a ventilation device for generating an air flow; a surface of the evaporation body is arranged in the air flow, which air flow causes evaporation of a small part of the liquid received by the evaporation body, whereby the remaining liquid part is cooled; a heat transfer working fluid conduit disposed directly below the evaporation body and having a second planar area smaller in size than the first planar area; said heat transfer working fluid line having a surface arranged to receive substantially all of the cooled liquid portion from said evaporative body in heat transfer relation, thereby heating said liquid portion; a flow accelerator disposed between the evaporation body and the heat transfer working fluid line for increasing a flow velocity of the unevaporated liquid to at least about 2.9 meters per second prior to contacting the heat transfer working fluid line; a liquid collector disposed between the evaporation body and the heat transfer working fluid conduit so as to collect the portion of the cooled liquid flowing from the first planar area substantially to the second planar area; a liquid collector arranged to receive substantially all of the heated liquid portion from the heat transfer working fluid line; and a liquid circulation mechanism arranged to return said heated liquid portion to said liquid distributor.

In another aspect, the present invention provides an evaporative cooler comprising: a liquid dispenser; an evaporation body having a surface and occupying a first planar area for receiving liquid from said liquid distributor and flowing over said surface and substantially throughout said first planar area; a ventilation device for generating an air flow; a surface of the evaporation body is arranged in the air flow, which air flow causes evaporation of a small part of the liquid received by the evaporation body, whereby the remaining liquid part is cooled; a heat transfer working fluid conduit disposed directly below the evaporation body and having a second planar area smaller in size than the first planar area; said heat transfer working fluid line having a surface arranged to receive substantially all of the cooled liquid portion from said evaporative body in heat transfer relation, thereby heating said liquid portion; a fluid collector disposed between said evaporation body and a planar region of said heat transfer working fluid, said fluid collector comprising a vertical space between said heat transfer working fluid conduit and said evaporation body, an air inlet of said air moving device being disposed in said space between said evaporation body and said heat transfer working fluid conduit, whereby, while said unevaporated fluid drips between said evaporation body and said heat transfer working fluid conduit, an air flow from said air inlet to said air moving device is configured to collect said unevaporated fluid flowing from said first region substantially to said second region; a liquid collector arranged to receive substantially all of the heated liquid portion from the heat transfer working fluid line; and a liquid circulation mechanism arranged to return said heated liquid portion to said liquid distributor.

Furthermore, the invention proposes a method for cooling a working fluid, comprising the steps of: dispensing a liquid onto a surface of an evaporative body, wherein the evaporative body occupies a first planar area; blowing air over the surface of the evaporation body to evaporate a small portion of the liquid, thereby cooling the remaining portion of the liquid; distributing and concentrating said cooled liquid portion at a flow velocity over a surface of a heat transfer working fluid circuit occupying a second planar area that is smaller than the first planar area, wherein the flow velocity of said cooled liquid portion is increased from a flow velocity at exit from said evaporator surface to at least about 2.9 meters per second; flowing a working fluid through said heat transfer working fluid line to transfer heat from said working fluid to said cooled portion of said liquid to heat said portion of said liquid; collecting heated liquid from said outer surface of said heat transfer working fluid conduit and recycling said portion of warmed liquid back to said evaporator, all within a single housing of an evaporative cooler.

Finally, the invention also proposes a method for cooling a working fluid, comprising the steps of: dispensing a liquid onto a surface of an evaporative body, wherein the evaporative body occupies a first planar area; blowing air over the surface of the evaporation body to evaporate a small portion of the liquid, thereby cooling the remaining portion of the liquid; distributing and collecting said cooled portion of said liquid over the surface of the heat transfer working fluid conduit by dripping said cooled portion of said liquid in a vertical space between said heat transfer working fluid conduit and said evaporator body and by positioning the air inlet of said air moving device in said space between said evaporator body and said heat transfer working fluid conduit such that said air flow from said air inlet to said air moving device concentrates said cooled portion of said liquid, wherein said heat transfer working fluid conduit occupies a second planar area that is less than the first planar area; flowing a working fluid through said heat transfer working fluid line to transfer heat from said working fluid to said cooled portion of said liquid to heat said portion of said liquid; collecting heated liquid from said outer surface of said heat transfer working fluid conduit and recycling said portion of warmed liquid back to said evaporator, all within a single housing of an evaporative cooler.

Preferably, the flow velocity of the cooled liquid portion as it exits the surface of the evaporative body until it contacts the heat transfer working fluid conduit is increased to at least about 2.9 meters per second.

While all of the prior art teaches a logical idea that flowing air through the coils will aid in the cooling process, the applicant has found such a surprising effect: passing additional air flow through the coil will only impair the performance of the wet packed bed and place the ventilation system on a greater air flow driving requirement, thereby consuming some additional air driving power. Although it is not critical to the claimed invention that there is no air flow through the heat transfer coil, the applicant has found that: if the airflow through the heat transfer coil is reduced or stopped completely, the overall performance of the evaporative cooler will be improved.

With the present invention, applicants have maximized the efficiency of the wet packing set by distributing the water to be cooled over a relatively large packing set shell planar area. This will increase the surface area of the water that comes into contact with the air stream and will minimize the need for ventilation.

The applicant has found that: surprisingly high heat transfer coefficients or U-values can be obtained if the liquid is dumped onto the heat transfer coil of the indirect heat exchanger at very high (or very concentrated) flow rates.

Applicants have recognized and utilized the benefits of increasing the liquid loading of the indirect heat transfer section (liquid amounts of 8 to 16 gallons per minute per square foot-22.75 to 45.48 liters per minute per square meter) while also avoiding the disadvantages of increasing the liquid loading of the wet packing set layers by designing the planar area of the indirect heat transfer coil to be less than the planar area of the packing set layers and by concentrating the liquid flow as it flows from the packing set layers to the coil.

In addition, the applicant has also found that: the U value can be increased in two ways, namely by increasing the liquid load on the heat transfer coil and/or increasing the velocity of the liquid through or across the heat transfer coil zone.

The applicant has found a surprising effect: the airflow through the coil can be freely highly focused and positioned at any desired location without regard to the geometry of the airflow by increasing the cooling airflow burden on the coil. In addition, the advantage of the increased water falling speed can be utilized to further improve the heat transfer coefficient of the coil.

In summary, in one embodiment, applicants have separated individual heat exchanger sections and made them more efficient-although each of the previous inventors have combined sections to some extent and wanted to achieve the most efficient device. Applicant's invention separates the packing set layers from the coil so that the packing set layers can achieve their maximum efficiency and the coil can also operate at its maximum efficiency.

Specifically, in one embodiment, an evaporative cooler embodying the design principles of the present invention includes a liquid distributor for distributing evaporative liquid (also commonly referred to simply as water) onto a gas/liquid contact body (wet packing set layer) having a surface for receiving liquid and occupying a first planar area for receiving liquid from the liquid distributor, over the surface and substantially throughout the first planar area. A ventilating device is provided for generating an air flow in which the surface of the contact body is arranged, the air flow causing a small portion of the liquid received by the contact body to evaporate, thereby cooling the remaining portion of the liquid that is not evaporated. A heat transfer working fluid circuit (heat transfer coil) is disposed substantially outside of the gas flow, the circuit having a second planar area that is smaller in size than the first planar area. The heat transfer coil has a surface configured to receive substantially all of the cooled liquid flowing from the contact body. A liquid collector is disposed between the contact body and the heat transfer coil to collect cooled liquid flowing from the first planar area to the second planar area. The cooled liquid is rapidly reheated as it passes over the surface of the heat transfer coil due to the heat absorbed by the working fluid circulating through the tube, thereby cooling the working fluid. A liquid collector receives substantially all of the heated liquid that splashes from the heat transfer working fluid line. A liquid circulation device returns the heated liquid to the liquid distributor so that the above-described cycle is repeatedly performed.

In one embodiment of the invention, an evaporative cooler includes a liquid distributor and an evaporative body for receiving liquid from the liquid distributor. A ventilation device is arranged to generate an air flow over the surface of the evaporation body, the air flow causing a small portion of the liquid received by the evaporation body to evaporate, thereby cooling the remaining portion of the unevaporated liquid. A heat transfer working fluid circuit is provided to receive substantially all of the cooled liquid from the evaporator. A flow accelerator is disposed between the evaporative body and the heat transfer working fluid line to accelerate the flow velocity of the cooled liquid to at least 9.5 feet per second (2.9 meters per second) prior to contacting the surface of the heat transfer working fluid line. The cooled liquid is rapidly heated as it flows over the surface of the heat transfer working fluid conduit, due to the cooling of the working fluid circulating in the conduit. A liquid collector is arranged to receive substantially all of the heated liquid from the heat transfer working fluid conduit surface. A liquid circulation mechanism is provided for returning heated (or collected) liquid to the liquid distributor.

In one embodiment of the present invention, there is provided a method for cooling a working fluid, comprising the steps of: the liquid is dispensed onto a surface of an evaporative body, wherein the evaporative body occupies a first planar area. Air is blown through the evaporation body to evaporate a portion of the liquid, thereby cooling the remaining portion of the liquid. Distributing and collecting the remaining portion of the cooled liquid over a surface of a heat transfer working fluid circuit, wherein the heat transfer working fluid circuit occupies a second planar area that is smaller than the first planar area, and wherein the circuit is maintained in an area substantially free of gas flow. The evaporatively cooled liquid flows through and around the heat transfer working fluid conduit to facilitate heat exchange between the working fluid and the evaporatively cooled liquid. In the process, the evaporatively cooled liquid is heated, and the fluid in the pipeline is cooled. Heated liquid from the outer surface of the heat transfer working fluid line is collected and recycled back to the evaporator.

An embodiment of the present invention provides advantages in that: if the coils were placed below the wet packing set in a factory-manufactured module assembly, the center of gravity of the module would be lowered, which would improve the transportability of the module. Once the structure is in place, the lower center of gravity is advantageous in various respects with respect to seismic loads, steel heavy loads, and wind loads, whether the modules are built in the factory or in the field.

In an embodiment of the invention, the coil is separated from the layer of wet fill packs and all six sides of the coil are readily accessible at ground level, thus facilitating access to the coil for inspection and cleaning thereof.

In some such embodiments of the invention: the coil is located substantially or entirely outside the air stream flowing through the cooler and there is little likelihood of scale forming on the coil as a result of the evaporation process. These scales, if not used as thermal insulators, can reduce the efficiency of heat transfer through the coil wall, thereby negatively affecting the heat transfer performance of the coil.

In addition, in embodiments of the present invention in which the coils are substantially or entirely outside of the air stream flowing through the cooler, air is prevented from being contaminated by dirt and debris that may be carried by the air and from being exposed to solar rays that may penetrate through the air holes or other apertures. Furthermore, in some cases, unintended heat transfer can occur with conventional coils exposed to the airflow, and in such embodiments where the coil is disposed substantially or entirely outside of the airflow, such problems can be avoided.

Drawings

FIG. 1 is a side sectional view of an induced draft, counter-flow evaporative cooler incorporating the design principles of the present invention;

FIG. 2 is a schematic side sectional view of the air-breathing counter-flow evaporative cooler taken generally along line II-II of FIG. 1 and rotated 90;

FIG. 3 is a schematic side sectional view taken generally along line III-III of FIG. 4, illustrating a suction cross-flow evaporative cooler incorporating the principles of the present invention;

FIG. 4 is a schematic partial side cross-sectional view of a suction cross-flow cooling tower taken at 90 to FIG. 3;

FIG. 5 is a schematic side cross-sectional view of a forced draft counterflow evaporative cooler incorporating the principles of the present design;

FIG. 6 is a schematic side sectional view of the forced draft counterflow evaporative cooler taken generally along the line VI-VI in FIG. 5 and rotated 90;

FIG. 7 is a schematic side cross-sectional view of a side-by-side configuration of a suction evaporative cooler embodying the principles of the present invention;

FIG. 8 is a schematic cross-sectional view taken generally along line VIII-VIII of FIG. 7;

FIG. 9 is a schematic cross-sectional view taken generally along line IX-IX in FIG. 2;

fig. 10 shows an alternative embodiment, which is drawn along the same sectional lines as fig. 9.

Detailed Description

The present invention relates to evaporative coolers and can be used in a wide variety of configurations and arrangements. While several structural arrangements of the present invention are shown herein, the invention may be practiced in a variety of other embodiments and configurations. For example, although the preferred embodiment is a factory built configuration, the invention is also applicable to on-site built evaporative coolers. Factory assembled units are typically built as one or two modules, while field built devices may be separate components or units that are built in their respective locations and not necessarily in the same housing. Other arrangements will be apparent to those skilled in the art from the following description of the preferred embodiment.

In fig. 1 and 2, an evaporative cooler, generally designated 20, which includes several structural components, to which the principles of the present invention are applied. There is shown a liquid distributor generally designated 22 and a direct heat transfer section generally designated 24 including an evaporative body 26, the evaporative body 26 having a surface for receiving liquid from the liquid distributor 22. A ventilation device is provided which generates an air flow over the surface of the evaporation body 26, which evaporates a small part of the liquid flowing over the evaporation body, thereby cooling the remaining part of the liquid. An indirect cooling zone is provided at 30 and generally comprises at least one, and preferably a plurality of heat transfer working fluid lines 32 in the form of loops or coils.

The evaporation body 26 is shown schematically and comprises a large surface area element with a plurality of air passages extending through the element. The surface of the evaporation body can take many different forms. In one form, the evaporation body may comprise a stack of mutually separated sheets of material, for example in which the sheets are oriented vertically so that evaporative liquid distributed over the surfaces of the sheets flows downwardly, and air passages are formed between the mutually separated sheets so that air flows through the sheets at the same time as liquid flows through the sheets. In a more specific and preferred embodiment, the sheet material may be non-planar and thus form a series of folds which increase the flow area of the liquid while still providing some air passage through the evaporation body. The evaporator body may also include a plurality of spaced-apart strips or even a series of spaced-apart tubes. Those skilled in the art will appreciate that: such an evaporative body member is referred to as a wet packing set layer, and hereinafter, the evaporative body 26 will be referred to as a wet packing set layer or a simple packing set layer. One particular type of wet packing set layer that has been found by applicants to be very effective and effective is disclosed in U.S. patent application No. 5124087, the disclosure of which is incorporated herein by reference.

The indirect heat transfer section is schematically illustrated and includes at least one heat transfer working fluid conduit 32 having a surface for receiving unevaporated liquid from the evaporation body 26. The conduit may take several forms including: a set of individual coils or tubes 54 connected by headers 56 to form an array of tubes, thereby increasing the surface area for engaging the unevaporated liquid. A particular coiled tube construction is disclosed in U.S. patent No. 4755331 in which the tube is oval in cross-section, but it is also noted that tubes of circular cross-section, or other cross-sectional configurations, may also be used. Alternatively, the conduits may be in the form of hollow plates having passages formed therein for the passage of a working fluid therethrough, the plates also having a surface area over which unevaporated liquid flows in indirect heat transfer relationship. A set of such plates may be used with the plates oriented vertically with appropriate connections and headers to allow the working fluid to flow through the plates. Hereinafter, the heat transfer working fluid line 32 will be referred to simply as a heat exchange coil, a heat transfer coil, or very simply as a coil.

In the embodiment shown in fig. 1 and 2, the width and depth of the packing set layer 26 substantially entirely occupy the width dimension W1 and the depth dimension D1 of the shell 34, with the shell 34 encasing the various components of the evaporative cooler 20. The heat transfer coil 32 occupies a width W2 and a depth D2, at least one of which is smaller than the corresponding width W1 and depth D1 occupied by the packing set layer 26. Thus, the planar area of the coil 32 is smaller than the planar area of the packing set layer 26.

In a preferred embodiment, the planar area of the coil 32 (the second planar area) is about 20% to about 90% of the planar area of the packing set layer 26 (the first planar area). In another preferred embodiment, the second planar area is about 25% to about 80% of the first planar area. In yet another preferred embodiment, the second planar area is about 40% to about 70% of the first planar area.

Fig. 9 is a cross-sectional view taken substantially along the line IX-IX in fig. 2, showing what is seen when viewed from above: the packing set layer 26 occupies a width W1 that is the full width of the shell 34, while the heat transfer coil 32 occupies a smaller width W2 and exits both side walls of the shell. It can be seen from the figure that: the planar area of the packing set layer 32, shown on the left-hand side of the figure, is greater than the planar area of the heat transfer coil 26 (shown on the right-hand side of the figure), and in fact, in the case shown, the former is about twice as great as the latter. In fig. 2, a liquid collection section 36 is provided between the packing set layer 26 and the heat transfer coil 26 to collect liquid that exits the packing set layer 26 but has not yet engaged the heat transfer coil 32. A liquid collector 38 is provided for collecting liquid flowing over the surface of the heat transfer coil 32. A liquid circulation flow mechanism 40 is also provided for returning heated liquid from the fluid collector 38 to the liquid distributor 22.

In the embodiment shown in fig. 1 and 2, the liquid distributor includes a set of individual nozzles 42 disposed in liquid passages 44, such as an array of tubes leading from a header 46. It can be understood that: a wide variety of liquid dispensers may be used in addition to the embodiment schematically shown in the figures. For example, instead of installing a plurality of individual nozzles 42, the tube 44 may be perforated. The fluid passageways may also be in the form of a single perforated tube or channel into which fluid is directed and from which it drips through the perforations onto the packing set layer 26. The passageway 44 may also be in the form of a closed tube, as shown, or may be in the form of an open-topped channel or channel. The exact configuration of the liquid distributor is not critical so long as it distributes liquid relatively evenly over the packing set 26 and allows the gas stream to be discharged therefrom.

The ventilation device 28 shown in fig. 1 and 2 is a blade-type fan that is disposed above the packing set layer 26. Beneath the wet packing set 26, a set of air inlets 48 are formed in the housing 34 so that air is drawn into the housing 34, flows through the packing set 26, and exits through a large opening 50 in the top of the housing, the opening 50 being located above the fan. In such an arrangement, which is known in the art as an induced draft, counter-flow system, a drift eliminator 52 is typically provided to remove entrained droplets from the airflow before it is expelled from the housing. There are a number of different types and configurations of drift eliminators in the prior art, including: closely spaced metal, plastic or wood slats/slats that allow air to pass through but retain fine water droplets contained in the air. In the illustrated construction, the collected water droplets will fall under gravity onto the wet packing set 26 with some additional distributed liquid.

It will be apparent to those skilled in the art that many other types of ventilation devices may be used, including: various configurations of blowers, movable diaphragms, and even ventilation devices without any moving parts, such as convection chimneys. The position of the vent 50 is variable and may be located on the side wall rather than the top wall if required to ensure a spatial arrangement. It can also be designed as follows: air is drawn downstream through the wet packed bed 26 in a concurrent fashion rather than in a counter-current fashion as shown. Also, the particular configuration and location of the venting means is not critical, but rather is important in that air is caused to flow over the surface of the packing set 26, upon which the liquid is spread. Those skilled in the art will appreciate that: in some cases, other different types of ventilation devices may be more suitable, depending on the desired air flow, noise level, allowable space, etc.

The liquid leaving the wet packed bed 26 is cooled by the evaporation process and, in some highly efficient systems, the temperature of the liquid is close to the ambient wet bulb temperature when air is drawn into the housing. The liquid will gradually increase in temperature as it flows down the heat transfer coil 32. In a preferred embodiment, the working fluid is introduced from the lower portion of the heat transfer coil 32 and flows gradually upward to exit at the upper portion, so that the working fluid is cooled as it flows upward, and at the highest location of the heat transfer coil, the temperature of the working fluid will be the lowest, where the liquid from the wet fill pack layer 26 also reaches the lowest temperature, so that the working fluid will be cooled to a temperature close to the wet bulb temperature of the ambient atmosphere, which is the lowest temperature that can be reached by an evaporative cooler. If the working fluid is a gas to be condensed, the gas must necessarily flow from the top to the bottom of the coil 32 due to the need for drainage, although the heat transfer efficiency is somewhat reduced in this direction of flow.

Other configurations and constructions of the heat transfer coil 32 will be apparent to those skilled in the art, and the exact construction thereof is not critical, but is important only in that: the tubing provides a passage for the working fluid and provides a surface for the cooled fluid to engage, and the coil is constructed of a material that transfers heat from the fluid to the liquid but does not allow the fluid or liquid to pass therethrough.

The housing 34 shown in the drawings is formed substantially by vertical outer walls that are arranged substantially perpendicular to each other so that the resulting shape is substantially cubic. This particular shape is convenient and economical to manufacture, but this feature is not essential to the invention and the shape of the housing may be varied, for example the cross-sectional shape of the housing may be circular or other geometric shape, in fact the various components may be mounted in different housings, not all of which are necessarily mounted in the same housing (as will become apparent, particularly for the embodiment shown in figure 7, which will be discussed below).

Although a different element is always used as the fluid collector, in the embodiment shown in fig. 1 and 2 the fluid collection section, designated by reference numeral 36, is formed by two elements. In the embodiment shown in fig. 1, 2, the air inlet 48 has a function of gathering liquid, because: air drawn through the side walls of the housing 34, as indicated by arrows 47, will enter upwardly and flow through the wet packed bed 26. As air is drawn inwardly into the air stream, liquid dripping downwardly from the layer of wet packed groups is impacted by the air stream and moves inwardly as indicated by arrows 51 under the influence of the air stream, thus collecting water dripping downwardly from the layer of wet packed groups towards the central portion of the housing, at least at the side where the air inlet 48 is located.

As schematically represented in fig. 9, the heat transfer coils 32 are spaced inwardly from the respective side walls of the housing 34 and air may enter from air inlets 48 on each side wall. However, in some applications it may not be possible, or feasible, to admit air from all sides, in which case the heat transfer coils 32 may be disposed directly adjacent the side walls. This is illustrated in fig. 10, where evaporative cooler 20 ' includes an evaporative body 26 ' and a heat transfer coil 32 ' disposed within a housing 34 ', with air inlets 48 ' disposed on only three of the side walls. Although the width of the wet packing set layer 26 'still occupies the full width W1' of the housing, the width W2 'occupied by the heat transfer working fluid coil 32' is smaller and the heat transfer coil is located immediately adjacent to the side wall that does not have an air inlet. The reason for this is that: there will be no air flow along this side wall without the air inlet 48 to exert a coalescing effect on the liquid flowing down the wet packing set layer 26. Of course, the number and location of the inlet openings may vary, and thus the inlet openings may be arranged on one or more side walls, and/or provided on the top wall, if the above-mentioned outlet openings 50 are displaced to the side walls.

Figures 1, 2 and 9 show that another possible concentrating element is a sloped wall 60 that extends inwardly from the outer wall of the housing 34 into the space occupied by the heat transfer coil. Thus, those liquid that flows down the wet packing set 26 and is not collected by the incoming air flow into the smaller planar area occupied by the heat transfer coil 32 will be directed into the smaller planar area by the sloped wall 60, and thus collected. In fig. 10, a sloping wall surface is also provided, which will be the only collection means for liquid flowing down that wall surface where no air inlet is provided. Thus, in the configuration shown in FIG. 10, the heat transfer coil 32 can be spaced from the wall surface, in which case the collection function is performed by the inclined wall surface 60 ', although no air inlet 48' is provided in the side wall at the top of the figure. Other structures and means for collecting liquid flowing from the first planar area occupied by the packing set layer 26 to the second planar area occupied by the heat transfer coil 32 will be apparent to those skilled in the art (other specific means will be described with reference to fig. 7).

Also, while various means for collecting liquid may be employed, such as channels, closed boxes or other means, in FIG. 10, the liquid collector 38 is embodied as a single catch basin and a water conduit disposed in the bottom of the housing, with the base water trough being in the form of an open pan. The collector is only important to collect and recycle the liquid to the liquid distributor 22.

For this purpose, a fluid circulation mechanism 40 is provided which includes a means for moving liquid collected in the liquid collector 38 to the liquid distributor 22. The liquid circulation mechanism 40 may take a variety of configurations including the provision of a pump 62 connected in a line 64 leading from the liquid collector 38 to the liquid distributor 22. The pump itself may be any type of existing pump, including: positive displacement pumps, centrifugal pumps, peristaltic pumps, etc. The liquid circulating mechanism can also adopt other structural forms, for example, a water-stirring wheel, a rotary screw rod, a liquid conveying device such as a conveying belt and a liquid bucket and the like can be adopted, and other structures can be easily conceived by a person skilled in the art, and it is required to point out that: the function of the liquid circulation means should be to simply carry liquid from the liquid collector 38 to the liquid distributor 22.

In the embodiment shown in fig. 1 and 2, the heat transfer working fluid coil 32 is located substantially outside of the airflow through the housing. That is, the flow path of the air is: flows through the air inlets 48 and up through the layer of wet packed material 26 and then through the drift eliminators 52 and out the air holes 50 through the ventilation 28. The applicant has determined that: the evaporation efficiency of modern wet packed beds is significantly higher than that of typical coils used for heat transfer working fluid lines. Thus, if additional air is drawn through the coils of the heat transfer working fluid circuit, additional energy will be required, either due to increased airflow or increased pressure drop, resulting in a less efficient evaporative cooler than if the heat transfer coils 32 were substantially outside the airflow through the evaporative cooler.

For the embodiment shown in fig. 1 and 2, the air has a tendency to flow over the top surface of the coil as it flows from the air inlet and up the wet packing set layers. There are even some possibilities: a portion of the air leaks (flows) into the housing around the lower wall and thus below the sloped wall surface 60. Although it is not strictly required that no airflow pass through the heat transfer coil 32, in a preferred embodiment the coil will be located substantially, if not entirely, outside the airflow to facilitate improved efficiency of the evaporative cooler.

As schematically illustrated, the air inlet 48 is in the form of a series of louvres that are oriented downwardly so that air flowing into the housing is first directed downwardly and then diverted upwardly toward the evaporation body 26. The inlet may also be of other known configurations including straight channels, chevron channels or serpentine channels. The air inlet 48 may be provided on each vertical wall surface of the housing, or may be provided on less than all of the wall surfaces (as in the case shown in fig. 10), or may not be provided on the entire outer peripheral surface of the housing.

The apparatus shown in fig. 1 and 2 also includes a flow accelerator 70 disposed between the series of wet packing layers 26 and the heat transfer coil 32 for increasing the falling flow velocity of liquid that has not yet contacted the heat transfer coil surface. In the embodiment shown in fig. 1 and 2, the flow accelerators include a vertical spatial separation of sufficient magnitude to achieve substantial acceleration of liquid dripping from the wet packing series 26 onto the heat transfer coils 32, preferably disposed at a distance of about 2 feet (0.61 meters) and up to 6 feet (1.8 meters) or more, thereby accelerating the liquid exiting the packing series 26 to a velocity of about 9.5 feet/second (2.9 meters/second) up to 15 feet/second (4.6 meters/second) or more.

Fig. 3 and 4 schematically illustrate another embodiment of an evaporative cooler 120 incorporating the principles of the present invention, which includes several structural components similar to those of the previous embodiment. Elements that are substantially similar to those described above are referred to by like reference numerals increased by 100, and are substantially the same as described above if they and their functions are not specifically described below.

The liquid distributor is generally indicated at 122 and the direct heat transfer section, indicated at 124, includes two spaced apart evaporative bodies 126 (wet or simple packing series) each having a surface for receiving liquid from the liquid distributor 122. Only the left filler layer group 126 is shown in fig. 4, but a typical arrangement would include an identical second filler layer group on the right. Other sets of packing layers can also be provided on the remaining two opposite sides, so that in a four-sided housing, 1 to 4 packing stacks can be provided, depending on the application.

As mentioned above, a ventilation device 128 is provided. An indirect cooling stage is provided at 130 and generally includes at least one, and preferably a plurality of heat transfer working fluid lines 132 in the form of loops or coils at one or more separate locations corresponding to the number of vaporizers provided.

In the embodiment shown in fig. 3 and 4, the width W3 occupied by the set of filler layers 126 is substantially the full width of the housing 134 enclosing the various components of the evaporative cooler 120, and the depth D3 is a fraction of the depth of the housing. The heat transfer coils 132 occupy a width W4 and a depth D4, at least one of which is less than the width W3 or depth D3 occupied by the corresponding set of filler layers 126. Thus, the planar area of the heat transfer coils 132 is less than the planar area of the set of packing layers 126.

As noted above, the planar area of the heat transfer coil 132 (the second planar area) may be about 20% to 90% of the planar area of the evaporation body (the first planar area), or in the range of about 25% to 80%, and may be about 40% to 70% of the first planar area. A liquid collection stage 136 is provided between each packing set 126 and the corresponding heat transfer coil 132. A liquid collector 138 is positioned to collect liquid that flows down the surface of the heat transfer coil 132. A liquid circulation mechanism 140 is provided for returning heated liquid from the liquid collector 138 to the fluid distributor 122.

The ventilation device 128 shown in fig. 3 and 4 is a blade fan which is arranged above the packing set 126. A set of air inlets 148 are formed in the housing 134 adjacent the set of filler layers 126 to draw air into the housing 134 and through the set of filler layers 126 in a cross-flow pattern, the air flow direction being substantially perpendicular to the evaporative liquid flow direction across the surface of the set of filler layers 126, and the air being discharged through a large opening 150 at the top of the housing above the fan. In this design, known in the art as a suction cross flow system, a drift eliminator 152 is also typically provided, as described above. In the illustrated construction, the collected water droplets will fall by gravity along with other non-vaporized liquid into the liquid collection section 136.

As mentioned above, many other ventilation means and corresponding positioning arrangements are readily conceivable to the person skilled in the art. Likewise, the exact configuration and location of the venting means is not critical to the invention, but is merely important to allow air to flow over the surface of the packing set 126 on which the liquid is distributed.

In the figures, indirect heat transfer section 130 is schematically represented as including at least one cooking coil 132 having a surface for receiving cooled liquid dripping from the series of packing layers 126. In the cross-flow configuration shown in fig. 3 and 4, two packing stacks 126 and two indirect heat transfer sections 130 are typically provided, but a single set of modules may be provided, or more than two sets of modules may be provided. The heat transfer coil 132 may take several of the forms described above.

Reference numeral 136 in the figure designates a liquid collection section which, in this embodiment, is comprised of a single element including a sloped wall surface 160 extending from the outer wall surface of the housing 134, which extends inwardly into the space occupied by the heat transfer coil 132. In this way, any liquid dripping from the filler layer package 126 will be directed by the inclined walls to a smaller planar area, and thus be collected. Other structures and devices for collecting liquid flowing from a first planar area occupied by the evaporative body to a smaller second planar area occupied by the heat transfer working fluid circuit will be readily apparent to those skilled in the art, in addition to those described above.

In the embodiment shown in fig. 3 and 4, the heat transfer coil 132 is located substantially outside of the air flow through the housing. That is, the air flowing in through the air inlet 148 will traverse the evaporator 126, then flow through the drift eliminators 152, and be discharged from the air holes 150 through the ventilation device 128.

The apparatus shown in fig. 3 and 4 also includes a flow accelerator 170, as described above, located between the series of packing layers 126 and the heat transfer coil 132 for increasing the flow velocity of the unevaporated liquid before it contacts the surface of the heat transfer coil.

Also, in this embodiment, the heat transfer coefficient U value can be increased by at least two ways: the liquid loading of the indirect heat transfer section 130 is greater than the loading of the direct heat transfer section 124 by concentrating the liquid between the direct heat transfer section and the indirect heat transfer section; and increasing the flow rate of the liquid through the indirect heat transfer section.

Fig. 5 and 6 schematically illustrate another embodiment of an evaporative cooler 220 that embodies principles of the present design and includes several structural components similar to those of the embodiments described above. Elements that are substantially similar to those described above are referred to by like reference numerals increased by 200, and if the elements and their functions are not described in detail below, the situation is substantially the same as that described above.

The liquid distributor is generally indicated by reference numeral 222 in the drawings and the direct heat transfer section, designated 224, includes an evaporator 226 (wet or simple set of packing layers) having a surface for receiving liquid from the liquid distributor 222.

As described above, a vent 228 is provided. An indirect cooling stage is provided at 230 and generally includes at least one, and preferably a plurality of heat transfer working fluid lines 232 in the form of loops or coils.

In the embodiment shown in fig. 5 and 6, the width W5 and depth D5 occupied by the set of filler layers 226 is substantially the full width and depth of the housing 234 enclosing the various components of the evaporative cooler 220. Heat transfer coil 232 occupies a width W6 and a depth D6, at least one of which is less than the corresponding width W5 or the corresponding depth D5 occupied by the group of filler layers 226. As such, the planar area of the heat transfer coil 232 is less than the planar area of the set of filler layers 226.

As noted above, the planar area of the heat transfer coil 232 (the second planar area) may be about 20% to 90% of the planar area of the filler layer group (the first planar area), or in the range of about 25% to 80%, and may be about 40% to 70% of the first planar area. A liquid collection section 236 is provided between the packing set 226 and the heat transfer coil 232 and collects liquid from the packing set 226 prior to joining to the heat transfer coil 232. A liquid collector 238 is positioned to collect liquid flowing down the surface of the heat transfer coil 232. A liquid circulation mechanism 240 is provided for returning heated liquid from the liquid collector 238 to the fluid distributor 222.

The ventilation device 228 in fig. 5 and 6 is represented by three blowers 249 disposed below the evaporation body 226. Three air inlets 248 are formed in the housing 234 below the set of packing layers 226 so that air can be drawn into the housing 234 and discharged through a large opening 250 above the blower after flowing through the set of packing layers 226 to the top of the housing. In this type of design, known in the art as a suction cross flow system, a drift eliminator 252 is also typically provided. In the illustrated construction, the collected droplets will fall under gravity along with other distributed liquid onto the evaporation body 226.

As mentioned above, many other ventilation means and corresponding positioning arrangements are readily conceivable to the person skilled in the art. Likewise, the exact configuration and location of the vent is not critical to the invention, but rather is important only to allow air to flow over the surface of the packing array 226 on which the liquid is distributed.

Indirect heat transfer stage 230 is schematically represented in the figure as including at least one heat transfer coil 232 having a surface for receiving cooled liquid dripping from the series of packing layers 226. The conduit may take several of the forms described above.

Reference numeral 236 in the figure designates a liquid collection section which, in this embodiment, is comprised of a single element including a sloped wall 260 extending from the outer wall surface of the housing 234 inwardly into the space occupied by the heat transfer coil 232. In this way, any liquid dripping from the packing set 226 will be directed by the inclined wall 260 towards a smaller planar area and thus be collected. Other structures and devices for collecting liquid flowing from a first planar area occupied by a packing set to a smaller second planar area occupied by a heat transfer coil will be readily apparent to those skilled in the art, in addition to those described above.

The apparatus shown in fig. 5 and 6 also includes a flow accelerator 270, as described above, located between the series of packing layers 226 and the heat transfer coil 232 for increasing the flow velocity of the unvaporized liquid before it contacts the heat transfer coil surface.

Also, in this embodiment, the heat transfer coefficient U value can be increased by at least two ways: the liquid loading of the indirect heat transfer stage 230 is greater than the loading of the direct heat transfer stage 224 by concentrating the liquid between the direct heat transfer stage and the indirect heat transfer stage; and increasing the flow rate of the liquid through the indirect heat transfer section.

Fig. 7 and 8 schematically illustrate yet another embodiment of an evaporative cooler 320 incorporating the principles of the present invention, which includes several structural components similar to those of the previous embodiment. Elements substantially similar to those described above are designated with like reference numerals increased by 300 and are substantially the same as described above if they are not specifically described below in their function.

The liquid distributor is generally indicated by reference numeral 322 and the direct heat transfer section, designated 324, includes an evaporative body 326 (wet or simple packing series) having a surface for receiving liquid from the liquid distributor 322.

In the embodiment illustrated in fig. 7 and 8, the width W7 and depth D7 occupied by the filler layer sets 326 are substantially the full width and depth of the housing 334 that encloses the various components of the evaporative cooler 320. The heat transfer coils 332 occupy a width W8 and a depth D8, at least one of which is less than the corresponding width W7 or the corresponding depth D7 occupied by the groups of filler layers 326. As such, the planar area of the heat transfer coils 332 is less than the planar area of the set of filler layers 326. As noted above, the planar area of the heat transfer working fluid conduits 332 (the second planar area) may be about 20% to about 90% of the planar area of the filler layer group (the first planar area), or in the range of about 25% to about 80% of the first planar area, and may be about 40% to about 70% of the first planar area. A liquid collection section 336 is provided between the packing set 326 and the heat transfer coils 332 and collects liquid from the packing set 226 prior to joining to the heat transfer coils 232. A liquid collector 338 is positioned to collect the warm-up liquid flowing down the surface of the heat transfer coil 232. A liquid circulation mechanism 340 is provided for returning heated liquid from the liquid collector 338 to the fluid distributor 322.

The aeration device 328 shown in fig. 7 is a bladed fan that is positioned above the packing set 326. Beneath the series of packing elements 326, the housing 334 is formed with a series of air inlets 348 so that air can be drawn into the housing 334 and discharged through the series of packing elements 326 and out the top of the housing through a large opening 150 located above the fan. In this design, which is known in the art as a side-by-side induced draft counterflow system, a drift eliminator 352 is also typically provided. In the illustrated construction, the collected droplets will fall by gravity along with other distributed liquid onto the evaporative body 326.

As mentioned above, many other ventilation means and corresponding positioning arrangements are readily conceivable to the person skilled in the art. Likewise, the exact configuration and location of the vent is not critical to the invention, but rather is important only to allow air to flow over the surface of the packing array 326 over which the liquid is distributed.

The indirect heat transfer section 330 is schematically represented in the figure as including at least one heat transfer coil 332 having a surface for receiving cooled liquid dripping from the series of packing layers 326. The fluid flow through the coil 332 may be arranged in the manner described above.

In this embodiment, the direct heat transfer section 324 is provided in one housing component and the indirect cooling section 330 is provided in a separate housing component, the two housing components being separated by a partition 369, although in the figures the two housing components are separated by a common partition therebetween, the partition need not be common, and the two housing components may be arranged at a distance and at different heights.

The liquid collection section is designated 336 in the figure and is comprised of a liquid collection area 372 for collecting cooled liquid dripping from the packing array 326. The liquid is pumped into a conduit 374 extending through the wall 369 and passes through a pump 376 upwardly to another conduit 378 and then to a liquid distributor 380 having nozzles or openings 382 for ejecting the liquid from the distributor 380. The nozzle or orifice 382 is at a sufficient height above the heat transfer working fluid line to facilitate acceleration of the liquid to a desired velocity under the influence of gravity as described above. The liquid may also be sprayed from the nozzle or orifice 382 with a sufficiently high pressure so that the velocity of the liquid may also be increased to an appropriate amount, for example, up to 9.5 feet/second (2.9 meters/second) or more. Preferably, the following steps are carried out: a communicating vessel or a liquid flow path is provided between the liquid collection zone 372 for collecting cooled liquid from the packing array 326 and the liquid collector 338 to balance flow variations between the collection zone 372 and the liquid collector 338. Since it is very difficult to have two pumps working simultaneously at exactly the same speed, the preferred design is: the circulation pump is slightly more flooded so that the cooled fluid from the packing set 326 can overflow into the fluid accumulator 338 to mix with the warmed fluid dripping from the heat transfer coil surface.

In the embodiment shown in fig. 7 and 8, the heat transfer coil 332 is located substantially outside of the air flow through the housing. That is, the air flow entering through the air inlet 348 will pass upwardly through the packing set 326, then pass through the drift eliminators 352 and exit the air holes 350 through the ventilation 328.

The apparatus shown in fig. 7 and 8 further includes a flow accelerator 370, as described above, positioned between the series of packing layers 326 and the heat transfer coil 332 for increasing the flow velocity of the unvaporized liquid prior to contacting the heat transfer coil surface, in which embodiment the flow accelerator 370 may include a pump 376, a conduit 374, a nozzle 382, and/or a separation distance between the nozzle 382 and the coil 332.

Also, in this embodiment, the heat transfer coefficient U value can be increased by at least two ways: the liquid loading of the indirect heat transfer section 330 is greater than the loading of the direct heat transfer section 324 by concentrating the liquid between the direct heat transfer section and the indirect heat transfer section; and increasing the flow rate of the liquid through the indirect heat transfer section.

As is apparent from the detailed description above: the invention may be embodied in many different forms and variations, which are specific only in nature and different from the specific embodiments described in the foregoing specification. It can thus be understood that: the applicant intends to embrace all reasonable modifications as long as they come within the scope of the present invention, based on the patent protection scope herein.

Claims

1. An evaporative cooler, comprising:

a liquid dispenser;

an evaporation body having a surface and occupying a first planar area for receiving liquid from the liquid distributor and flowing over the surface and substantially throughout the first planar area;

a ventilation device for generating an air flow;

a surface of the evaporation body is arranged in the air flow, which air flow causes evaporation of a small part of the liquid received by the evaporation body, whereby the remaining liquid part is cooled;

a heat transfer working fluid conduit disposed substantially outside of said gas stream, the conduit having a second planar area that is smaller in size than said first planar area;

said heat transfer working fluid line having a surface arranged to receive substantially all of the cooled liquid portion from said evaporative body in heat transfer relation, thereby heating said liquid portion;

a flow accelerator disposed between the evaporation body and the heat transfer working fluid line for increasing a flow velocity of the unevaporated liquid to at least about 2.9 meters per second prior to contacting the heat transfer working fluid line;

a liquid collector disposed between the evaporation body and the heat transfer working fluid conduit so as to collect the unevaporated liquid flowing from the first planar area substantially to the second planar area;

a liquid collector arranged to receive substantially all of the heated liquid portion from the heat transfer working fluid line; and

a liquid circulation mechanism arranged to return said heated liquid portion to said liquid distributor.

2. The evaporative cooler of claim 1, wherein: the liquid collector includes an open pan.

3. The evaporative cooler of claim 1, wherein: the liquid collector includes a conduit.

4. The evaporative cooler of claim 1, wherein: the liquid circulation mechanism includes a pump.

5. The evaporative cooler of claim 1, wherein: the liquid dispenser includes at least one nozzle.

6. The evaporative cooler of claim 1, wherein: the liquid distributor includes a porous liquid channel.

7. The evaporative cooler of claim 1, wherein: the evaporative body includes a wet filler layer set.

8. The evaporative cooler of claim 1, wherein: the evaporation body comprises a stack of vertically oriented thin layers of material.

9. The evaporative cooler of claim 8, wherein: the sheet material is non-planar.

10. The evaporative cooler of claim 1, wherein: the ventilation device comprises a fan.

11. The evaporative cooler of claim 1, wherein: the ventilation device comprises a blower.

12. The evaporative cooler of claim 1, wherein: the heat transfer working fluid circuit includes at least one coil.

13. The evaporative cooler of claim 1, wherein: the heat transfer working fluid line is located entirely outside of the airflow.

14. The evaporative cooler of claim 1, wherein: the heat transfer working fluid line is disposed directly below the evaporation body.

15. The evaporative cooler of claim 1, wherein: the heat transfer working fluid pipeline is located beside the evaporation body.

16. The evaporative cooler of claim 1, wherein: the liquid collector includes an inclined wall surface extending into a space between the evaporation body and the heat transfer working fluid pipe.

17. The evaporative cooler of claim 1, wherein: the fluid collector includes a fluid collector configured to receive substantially all of the unevaporated fluid from the evaporative body and a fluid distributor configured to distribute substantially all of the unevaporated fluid to the heat transfer working fluid circuit at the same rate at which the fluid is received from the evaporative body.

18. The evaporative cooler of claim 1, wherein: the ventilation means is arranged to generate the air flow in a direction opposite to the direction of flow of the liquid over the evaporator surface.

19. The evaporative cooler of claim 1, wherein: the ventilation means is arranged to generate the air flow in a direction substantially perpendicular to the direction of flow of the liquid across the surface of the evaporation body.

20. The evaporative cooler of claim 1, wherein: the second planar area is about 20% to 90% of the first planar area.

21. The evaporative cooler of claim 1, wherein: the second planar area is about 25% to 80% of the first planar area.

22. The evaporative cooler of claim 1, wherein: the second planar area is about 40% to 70% of the first planar area.

23. The evaporative cooler of claim 1, wherein: the heat transfer working fluid circuit comprises a coil assembly having an inlet located below an outlet thereof such that liquid working fluid entering from the inlet will flow upwardly through the coil assembly and exchange thermal energy with the cooled liquid portion through the wall of the coil, wherein the cooled liquid portion flows downwardly thereby cooling the liquid working fluid and the liquid working fluid exits the coil through the outlet.

24. The evaporative cooler of claim 1, wherein: the heat transfer working fluid circuit comprises a coil assembly having an inlet positioned above an outlet thereof such that gaseous working fluid entering from the inlet will flow downwardly through the coil assembly and exchange thermal energy with the cooled liquid portion through the wall of the coil, wherein the cooled liquid portion flows downwardly thereby condensing the gaseous working fluid into a liquid and the working fluid flows out of the coil through the outlet.

25. The evaporative cooler of claim 1, wherein: the flow accelerator includes a vertical space between the heat transfer working fluid conduit and the evaporator, and has a dimension of at least 0.61 meters.

26. The evaporative cooler of claim 1, wherein: the liquid collector includes a vertical space between the heat transfer working fluid conduit and the evaporation body, and the air inlet of the ventilation device is disposed in the space between the evaporation body and the heat transfer working fluid conduit, so that the air flow from the air inlet to the ventilation device concentrates the unevaporated liquid flowing from the first region substantially to the second region while the unevaporated liquid drips between the evaporation body and the heat transfer working fluid conduit.

27. An evaporative cooler, comprising:

a liquid dispenser;

an evaporation body having a surface for receiving liquid from the liquid distributor;

-ventilation means arranged to generate an air flow over the surface of said evaporation body, said air flow causing a small portion of said liquid received by said evaporation body to evaporate, thereby cooling the remaining portion of said liquid;

a heat transfer working fluid conduit arranged to receive substantially all of the cooled liquid portion from the evaporative body in heat transfer relation, thereby heating the remaining liquid portion;

a flow accelerator located between the evaporation body and the heat transfer working fluid line for accelerating the flow velocity of the cooled liquid to at least about 2.9 meters per second prior to contacting the heat transfer working fluid line surface;

a liquid collector arranged to receive substantially all of the heated liquid portion from the surface of the heat transfer working fluid line;

a liquid circulation mechanism; and

liquid passages connecting the liquid container, the circulation mechanism, and the liquid distributor.

28. The evaporative cooler of claim 27, wherein: the flow accelerator includes an open plenum between the evaporator and the heat transfer working fluid line.

29. The evaporative cooler of claim 27, wherein: the flow accelerator includes a pump and nozzle system.

30. The evaporative cooler of claim 27, wherein: the heat transfer working fluid line is located substantially outside of the gas stream.

31. The evaporative cooler of claim 27, wherein: said evaporator body having a surface and occupying a first planar area for receiving liquid from said liquid distributor and flowing over said surface and substantially throughout said first planar area, said heat transfer working fluid conduit having a second planar area smaller in size than said first planar area; and a liquid collector disposed between said evaporation body and said heat transfer working fluid conduit for collecting said unevaporated liquid flowing from said first planar area to said second planar area.

32. An evaporative cooler, comprising:

a liquid dispenser;

an evaporation body for receiving liquid from the liquid distributor;

ventilation means arranged to generate an airflow through said evaporation body, said airflow causing a small portion of said liquid received by said evaporation body to evaporate, thereby cooling the remaining portion of said liquid;

heat transfer working fluid conduits disposed at spaced apart locations downwardly relative to said evaporation body such that said cooled liquid portion flowing from said evaporation body is accelerated by gravity at a flow rate of at least about 2.9 meters per second prior to contacting a surface of said heat transfer working fluid conduits;

a liquid collector arranged to receive substantially all liquid from the surface of the heat transfer working fluid line;

a liquid circulation mechanism; and

liquid lines connecting the liquid container, the circulation mechanism, and the liquid distributor.

33. The evaporative cooler of claim 32, wherein: the heat transfer working fluid line is located substantially outside of the gas stream.

34. The evaporative cooler of claim 32, wherein: said evaporator body having a surface and occupying a first planar area for receiving liquid from said liquid distributor and flowing over said surface and substantially throughout said first planar area, said heat transfer working fluid conduit having a second planar area smaller in size than said first planar area; and a liquid collector disposed between the evaporation body and the heat transfer working fluid conduit to collect the cooled liquid flowing from the first planar area to the second planar area.

35. A method for cooling a working fluid, comprising the steps of:

dispensing a liquid onto a surface of an evaporation body;

blowing air over the surface of the evaporation body to evaporate a small portion of the liquid, thereby cooling the remaining portion of the liquid;

accelerating the cooled portion of the liquid to a velocity of at least about 2.9 meters per second and directing the liquid to a surface of a heat transfer working fluid circuit;

flowing a working fluid through said heat transfer working fluid line to transfer heat from said working fluid to said cooled portion of said liquid to heat said portion of said liquid;

collecting heated liquid from said outer surface of said heat transfer working fluid conduit and recycling said warmed liquid portion back to said evaporator.

36. The method of claim 35, wherein: the heat transfer working fluid circuit is maintained in an area where there is substantially no airflow.

37. An evaporative cooler, comprising:

a liquid dispenser;

an evaporation body having a surface and occupying a first planar area for receiving liquid from said liquid distributor and flowing over said surface and substantially throughout said first planar area;

a ventilation device for generating an air flow;

a fluid collector disposed between said evaporation body and a planar region of said heat transfer working fluid, said fluid collector comprising a vertical space between said heat transfer working fluid conduit and said evaporation body, an air inlet of said air moving device being disposed in said space between said evaporation body and said heat transfer working fluid conduit, whereby, while said unevaporated fluid drips between said evaporation body and said heat transfer working fluid conduit, an air flow from said air inlet to said air moving device is configured to collect said unevaporated fluid flowing from said first region substantially to said second region;

38. The evaporative cooler of claim 37, wherein: further comprising a flow accelerator disposed between the evaporative body and the heat transfer working fluid line, the flow accelerator increasing the flow velocity of the non-evaporative liquid to at least about 2.9 meters per second prior to contacting the heat transfer working fluid line.

39. An evaporative cooler, comprising:

a liquid dispenser;

an evaporation body having a surface and comprising a stack of vertically oriented sheets of material, wherein said sheets of material are non-planar and occupy a first planar area for receiving liquid from said liquid distributor and flowing over said surface and substantially throughout said first planar area;

a ventilation device for generating an air flow;

a flow accelerator disposed between the evaporation body and the heat transfer working fluid line for increasing a flow velocity of the unevaporated liquid;

40. The evaporative cooler of claim 39, wherein: the flow accelerator increases the flow velocity of the non-vaporized liquid to at least about 2.9 meters per second prior to contacting the heat transfer working fluid line.

41. The evaporative cooler of claim 40, wherein: the flow accelerator includes a vertical space between the heat transfer working fluid conduit and the evaporator, and has a dimension of at least 0.61 meters.

42. The evaporative cooler of claim 39, wherein: the liquid collector includes a vertical space between the heat transfer working fluid conduit and the evaporation body, and the air inlet of the ventilation device is disposed in the space between the evaporation body and the heat transfer working fluid conduit, so that the air flow from the air inlet to the ventilation device concentrates the unevaporated liquid flowing from the first region substantially to the second region while the unevaporated liquid drips between the evaporation body and the heat transfer working fluid conduit.

43. An evaporative cooler, comprising:

a liquid dispenser;

a ventilation device for generating an air flow;

44. The evaporative cooler of claim 43, wherein: the flow accelerator includes a vertical space between the heat transfer working fluid conduit and the evaporator, and has a dimension of at least 0.61 meters.

45. An evaporative cooler, comprising:

a liquid dispenser;

a ventilation device for generating an air flow;

a heat transfer working fluid conduit disposed directly below the evaporation body and having a second planar area smaller in size than the first planar area;

a liquid collector disposed between the evaporation body and the heat transfer working fluid conduit so as to collect the portion of the cooled liquid flowing from the first planar area substantially to the second planar area;

46. The evaporative cooler of claim 45, wherein: the heat transfer working fluid line is located substantially outside of the gas stream.

47. An evaporative cooler, comprising:

a liquid dispenser;

a ventilation device for generating an air flow;

48. The evaporative cooler of claim 47, wherein: further comprising a flow accelerator disposed between the evaporative body and the heat transfer working fluid line, the flow accelerator increasing the flow velocity of the non-evaporative liquid to at least about 2.9 meters per second prior to contacting the heat transfer working fluid line.

49. A method for cooling a working fluid, comprising the steps of:

dispensing a liquid onto a surface of an evaporative body, wherein the evaporative body occupies a first planar area;

distributing and concentrating said cooled liquid portion at a flow velocity over a surface of a heat transfer working fluid circuit occupying a second planar area that is smaller than the first planar area, wherein the flow velocity of said cooled liquid portion is increased from a flow velocity at exit from said evaporator surface to at least about 2.9 meters per second;

collecting heated liquid from said outer surface of said heat transfer working fluid conduit and recycling said portion of warmed liquid back to said evaporator, all within a single housing of an evaporative cooler.

50. The method of claim 49, wherein: the heat transfer working fluid circuit is maintained in an area where there is substantially no airflow.

51. A method for cooling a working fluid, comprising the steps of:

distributing and collecting said cooled portion of said liquid over the surface of the heat transfer working fluid conduit by dripping said cooled portion of said liquid in a vertical space between said heat transfer working fluid conduit and said evaporator body and by positioning the air inlet of said air moving device in said space between said evaporator body and said heat transfer working fluid conduit such that said air flow from said air inlet to said air moving device concentrates said cooled portion of said liquid, wherein said heat transfer working fluid conduit occupies a second planar area that is less than the first planar area;

52. The method of claim 51, wherein: the flow velocity of the cooled liquid portion increases to at least about 2.9 meters per second as it exits the surface of the evaporative body until contacting the heat transfer working fluid conduit.