Patent Description:
Existing evaporative cooling technologies, such as existing wet surface air coolers for industrial applications, have a large footprint and high operating cost.

A traditional wet surface air cooler (WSAC) (e.g., evaporative cooler) is comprised of a tube bundle for facilitating process fluid flow, a spray system that distributes water over a top of the tube bundle, and a fan or a set of fans that pulls air through the tube bundle. The air/spray water mixture on the outside surfaces of the tubes provides an evaporative cooling effect that removes heat from the process fluid and then rejects the heat out of both the fan stack and back into a spray water collection basin.

For instance, <CIT> (herein "<NUM> patent"), discloses an evaporative cooler including a direct heat transfer section <NUM> separated from an indirect cooling section or indirect heat transfer section <NUM> by a wall <NUM>, the wall <NUM> extending to a liquid collector <NUM> (e.g., a basin), and the liquid collector <NUM> collecting water ejected from nozzles <NUM> of the direct heat transfer section <NUM> and water ejected from nozzles <NUM> of the indirect cooling section <NUM>. Pumps <NUM> and <NUM> are provided for recirculating water from the liquid collector <NUM> to respective nozzles <NUM>, <NUM> (<NUM> Patent FIG. <NUM> and column <NUM>, lines <NUM>-<NUM>). Further, the <NUM> Patent discloses that the direct heat transfer section <NUM> includes a wet deck fill <NUM>, a drift eliminator <NUM> and "the air flows in through air inlets <NUM> and up through the fill <NUM> to pass through the drift eliminator <NUM> and past the air moving device <NUM> to exit through the opening <NUM>" (<NUM> Patent FIG. <NUM>, column <NUM>, lines <NUM>-<NUM> and column <NUM>, lines <NUM>-<NUM>). The <NUM> Patent discloses that it is desired to have the coil <NUM> outside of the air flow, which is achieved by the wall <NUM>, such that "the heat transfer coil <NUM> is positioned substantially outside of the flow of air through the housing" to reduce the need for additional flow requirements and reduce the need for "extra air moving horsepower" (<NUM> Patent column <NUM>, lines <NUM>-<NUM> and column <NUM>, lines <NUM>-<NUM>).

<CIT> discloses a heat exchange system comprising a vertical centermost plenum surrounded by a heat exchange coil of tubes and housed in a plurality of side panels and a base. The plurality of side panels have air intakes that communicate outside air into the cabinet above the heat exchange coil and sprayers. A stream of spray water and air is drawn downwardly over a heat exchange coil. A portion of the spray water is separated from the air by drawing the air inward to the plenum. The air is then drawn upwardly within the plenum to an exhaust external to the enclosure by a fan.

The present invention is directed to utilizing a spiral plate type heat exchanger for a wet surface air cooler, in combination with evaporative cooling technology, to provide a more efficient and compact solution to industrial cooling applications.

The present invention enhances the evaporative cooling process of the WSAC by utilizing an evaporative spiral (i.e., spiral shaped) plate heat exchanger in place of a tube bundle, where the evaporative spiral plate type heat exchanger is exposed to evaporative cooling. A spiral plate heat exchanger may be referred to as a spiral heat exchanger. A cooling medium, such as water, is sprayed on the outside heat transfer surfaces of the evaporative spiral plate heat exchanger and air is either pushed or pulled, via a fan, through open passageways in the evaporative spiral plate heat exchanger to produce an evaporative cooling effect.

The present invention is operable in both co-current and counter-current arrangements with respect to the direction of air flow through the evaporative spiral plate heat exchanger and the direction of the sprayed cooling medium, depending on how the fan is positioned. The present invention may further comprise a direct heat exchange section comprised of cooling tower fill to cool the spray water down and provide further increase to the heat transfer efficiency.

A wet surface air cooler (WSAC) includes an evaporative spiral plate heat exchanger including a first channel configured to receive a process medium, a spray system configured to spray a cooling medium onto the spiral plate heat exchanger, and a fan configured to force air to flow through the evaporative spiral plate heat exchanger, wherein the combination of the sprayed cooling medium onto the evaporative spiral plate heat exchanger and the air flowing through the evaporative spiral plate heat exchanger causes the cooling medium to at least partially evaporate to cause a temperature of the process medium to decrease.

The first channel of the evaporative spiral plate heat exchanger may have a spiral shape and include a plurality of winds for flowing the process medium, the evaporative spiral plate heat exchanger may further include a set of second channels extending axially through the evaporative spiral plate heat exchanger for receiving air and cooling medium, and each second channel may be provided between winds of the first channel.

The first channel may be a closed path extending between an inlet and an outlet and is closed at top and bottom surfaces of the evaporative spiral plate heat exchanger, and the second channels may be open at the top and bottom surfaces of the evaporative spiral plate heat exchanger.

The inlet may be provided at a radial center of the evaporative spiral plate heat exchanger and the outlet may be provided at an outermost radial surface of the evaporative spiral plate heat exchanger, or the inlet may be provided at the outermost radial surface of the evaporative spiral plate heat exchanger and the outlet may be provided at the radial center of the evaporative spiral plate heat exchanger.

The evaporative spiral plate heat exchanger may have a cross-flow arrangement in which a direction of air and/or the cooling medium flowing through the second channels is perpendicular to a direction of the process medium flowing through the first channel.

The WSAC may further comprise a lower housing including a plurality of airflow passages and a basin, the basin may be configured to receive the cooling medium sprayed by the spray system.

The airflow passages of the lower housing may be configured to allow air to flow from inside of the WSAC to outside of the WSAC or from outside of the WSAC to inside of the WSAC. The fan may be provided above the evaporative spiral plate heat exchanger, and the evaporative spiral plate heat exchanger may be provided on the lower housing.

The lower housing may be a lower module, and the fan and the spray system may be part of an upper module, and the upper module may be configured to be removably fastened to an upper surface of the evaporative spiral plate heat exchanger and the lower module may be configured to be removably fastened to a lower surface of the evaporative spiral plate heat exchanger.

The fan, the spray system and the evaporative spiral plate heat exchanger may be stacked in a vertical direction.

The spray system may be a concentric spray system including a plurality of distribution channels that are spaced from one another to distribute the cooling medium over the evaporative spiral plate heat exchanger.

The fan may be horizontally spaced from the evaporative spiral plate heat exchanger.

The WSAC may further comprise a lower housing including a basin, the basin may be configured to receive the cooling medium sprayed by the spray system, the fan and the evaporative spiral plate heat exchanger may be provided on a top surface of the lower housing, and the spray system may be provided above the evaporative spiral plate heat exchanger.

The fan may be configured to force air across the basin and through the evaporative spiral plate heat exchanger or through the evaporative spiral plate heat exchanger and across the basin.

The spiral plate heat exchanger may include at least one spiral sheet wound to form the first channel. The wound at least one spiral sheet may also form the second channel. Thus, the spiral plate heat exchanger may include at least one spiral sheet wound to form the first channel and the second channel. The at least one spiral sheet may separate the first channel and the second channel.

The spiral plate heat exchanger may include a spiral body formed by the wound at least one spiral sheet. Distance members may be attached to said at least one spiral sheet to separate the windings of said at least one spiral sheet. The spiral body may be enclosed by a substantially cylindrical shell.

A method of cooling with a wet surface air cooler (WSAC), the WSAC may comprise an evaporative spiral plate heat exchanger including a first channel configured to receive a process medium, a spray system configured to spray a cooling medium onto the spiral plate heat exchanger, and a fan configured to force air to flow through the evaporative spiral plate heat exchanger, the method may comprise flowing the process medium through the first channel, and simultaneously spraying, by the spray system, the cooling medium and operating the fan to flow air through the evaporative heat exchanger and cause the cooling medium to at least partially evaporate and cause a temperature of the process medium to decrease.

The first channel of the evaporative spiral plate heat exchanger may have a spiral shape and includes a plurality of winds for flowing the process medium, and the evaporative spiral plate heat exchanger may further include a set of second channels extending axially through the evaporative spiral plate heat exchanger, each second channel is provided between winds of the first channel, the method further comprising, during the simultaneously spraying the cooling medium and operating the fan, flowing the cooling medium and air through the second channels in a same direction or in opposite directions. The first channel may be a closed path extending between an inlet and an outlet and is closed at top and bottom surfaces of the evaporative spiral plate heat exchanger, and the second channels may be open at the top and bottom surfaces of the evaporative spiral plate heat exchanger, said method may further comprise flowing the process medium from a center of the evaporative spiral plate heat exchanger, radially outwardly through the first channel to an outer surface of the evaporative spiral plate heat exchanger, allowing the cooling medium to flow downwardly through gravity, and forcing the air upwardly, opposite to the direction of the cooling medium.

The first channel may be a closed path extending between an inlet and an outlet and may be closed at top and bottom surfaces of the evaporative spiral plate heat exchanger, and the second channels may be open at the top and bottom surfaces of the evaporative spiral plate heat exchanger, the method may further comprise flowing the process medium from an outer surface of the evaporative spiral plate heat exchanger, radially inwardly through the first channel to a center of the evaporative spiral plate heat exchanger, allowing the cooling medium to flow downwardly through gravity, and forcing the air upwardly, opposite to the direction of the cooling medium.

The fan and the spray system may be part of an upper module, and the WSAC may further comprise a lower module including a plurality of airflow passages and a basin, the method may further comprise removably fastening the upper module to an upper surface of the evaporative spiral plate heat exchanger and removably fastening the lower module to a lower surface of the evaporative spiral plate heat exchanger.

The spiral plate heat exchanger of the present invention provides more efficient heat transfer and thus require less surface area, resulting in a more compact WSAC with a drastically reduced footprint over a traditional WSAC.

Further scope of applicability of the invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating embodiments of the invention, are given by way of illustration only, since various changes and modifications within the scope of the invention as defined in the appended claims will become apparent to those skilled in the art from this detailed description.

The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus are not limitative of the present invention, and wherein:.

<FIG> is a cross-sectional view of the WSAC according to an embodiment of the present invention. <FIG> is a cross-sectional perspective view of the WSAC according to an embodiment of the present invention. <FIG> is a perspective cross-sectional view illustrating the evaporative spiral plate heat exchanger according to an embodiment of the present invention.

The WSAC <NUM> according to a first embodiment of the present invention includes an upper module <NUM>, a lower module <NUM>, and an evaporative spiral plate heat exchanger <NUM>.

The upper module <NUM> includes a fan <NUM> (e.g., exhaust fan) having a fan motor <NUM>, a spray system <NUM> having a plurality of distribution channels <NUM> and a first passage <NUM>. The fan <NUM> and fan motor <NUM> may be provided within a housing of the upper module <NUM>. Further, the center of the fan <NUM> may be centrally located within the upper housing. The distribution channels <NUM> may be in the form of nozzles, holes in a slotted pipe, or the like. The spray system <NUM> may be a concentric spray system <NUM> and the plurality of distribution channels <NUM> may be equally spaced from one another along a circumference of the upper module <NUM> to distribute the cooling medium over (i.e., over the top of) the evaporative spiral plate heat exchanger <NUM>. Alternatively, the plurality of distribution channels <NUM> may have any spacing from one another and may be provided on any surface of the upper module <NUM>, so as to distribute the cooling medium over (i.e., over the top of) the evaporative spiral plate heat exchanger <NUM>.

Each of the upper module <NUM>, the lower module <NUM> and the evaporative spiral plate heat exchanger <NUM> may be provided with flanges to allow for connection between the upper module <NUM>, the lower module <NUM> and the evaporative spiral plate heat exchanger <NUM>. The lower module <NUM> may be a lower housing <NUM>.

The upper module <NUM> may be removably coupled to a top surface (e.g., a top flange) of the evaporative spiral plate heat exchanger <NUM>, via fasteners (i.e., bolts, screws, rivets, etc.), and the lower module <NUM> may be removably coupled to a bottom surface (e.g., a bottom flange) of the evaporative spiral plate heat exchanger <NUM>, via fasteners (i.e., bolts, screws, rivets, etc.). In case the spiral plate heat exchanger comprises a shell <NUM>, the shell <NUM> may be provided with the flanges, such as the top flange and the bottom flange. Further, the evaporative spiral plate heat exchanger <NUM> may be vertically stacked onto the lower module <NUM>, and the upper module <NUM> may be vertically stacked onto the evaporative spiral plate heat exchanger <NUM>, such that the upper module <NUM>, the lower module <NUM> and the evaporative spiral plate heat exchanger <NUM> are in a vertically stacked configuration, as shown in <FIG> and <FIG>.

The upper module <NUM> may be removably coupled to the top surface of the evaporative spiral plate heat exchanger <NUM> in order to permit easy replacement with another upper module <NUM> having a different configuration, such as a different height, a different fan size, and/or a different shape. Similarly, the lower module <NUM> may be removably coupled to the bottom surface of the evaporative spiral plate heat exchanger <NUM> in order to permit easy replacement with another lower module <NUM> having a different number or size of the airflow passages <NUM>, a differently sized basin and/or a different shape.

The WSAC <NUM>, including the upper module <NUM>, the lower module <NUM> and the evaporative spiral plate heat exchanger <NUM>, may have a circular cross-sectional shape. The plurality of distribution channels <NUM> of the spray system <NUM> may be located around a circumference of the spray system <NUM> to form a concentric spray pattern, which causes an even distribution of cooling medium onto the evaporative spiral plate heat exchanger <NUM>. Further, the plurality of distribution channels <NUM> may be evenly spaced or randomly spaced around the circumference of the spray system <NUM>. The spray system <NUM> may spray water or any other known cooling medium onto the evaporative spiral plate heat exchanger <NUM>, to be collected in the basin <NUM>.

Alternatively, the upper module <NUM>, the lower module <NUM> and the evaporative spiral plate heat exchanger <NUM> may have any cross-sectional shape, including any polygonal shape (i.e., rectangular, pentagonal, hexagonal), an elliptical shape, etc..

The lower module <NUM> includes a basin <NUM> that collects water sprayed from the spray system <NUM>, one or more airflow passages <NUM>, a pump <NUM>, a first fluid line <NUM> and a second fluid line <NUM>. The one or more airflow passages <NUM> may be evenly spaced around a circumference of the lower module <NUM>, and the number of airflow passages <NUM> and the size of each airflow passage <NUM> may be modified to optimize air flow through the WSAC <NUM>. Further, <FIG> shows the one or more airflow passages <NUM> positioned at a top portion of the lower module <NUM>, however, the one or more airflow passages <NUM> may be positioned at any height along the lower module <NUM>.

In a counter-current arrangement of the WSAC <NUM>, the fan <NUM> draws in air through the one or more airflow passages <NUM>, upwards through the evaporative spiral plate heat exchanger <NUM>, and out through the first passage <NUM>. That is, the upward direction of airflow through the WSAC <NUM> is counter to the downward direction of cooling medium sprayed by the distribution channels <NUM> (i.e., due to the gravity force).

Alternatively, in a co-current arrangement of the WSAC <NUM>, the fan <NUM> pushes air down from the first passage and down through the evaporative spiral plate heat exchanger <NUM>, and finally out through the one or more airflow passages <NUM>. That is, the downward direction of airflow through the WSAC <NUM> is co-current to the downward direction of cooling medium sprayed by the distribution channels <NUM>.

The cooling medium that is collected in the basin <NUM> is recycled by the pump <NUM>, the first fluid line <NUM> and the second fluid line <NUM>. Specifically, the collected cooling medium is pumped, by the pump <NUM>, through the first fluid line <NUM>, then through the second fluid line <NUM> to the spray system <NUM>. The spray system <NUM>, via the distribution channels <NUM>, sprayed the cooling medium onto the evaporative spiral plate heat exchanger <NUM> in a continuous manner. That is, the pumped <NUM> may provide a continuous flow of cooling medium to the spray system <NUM>, and the spray system <NUM> may continuously spray the cooling medium onto the evaporative spiral plate heat exchanger <NUM>.

As illustrated in <FIG> and <FIG>, the evaporative spiral plate heat exchanger <NUM> includes an inlet <NUM>, and outlet <NUM>, a first channel <NUM> (i.e., first fluid channel) and second channels <NUM>. The first channel <NUM> is connected to the inlet <NUM> and to the outlet <NUM> and has a spiral configuration (i.e., spiral shaped cross-sectional profile). That is, the first channel <NUM> begins at a cross-sectional center of the evaporative spiral plate heat exchanger <NUM> and spirals radially outward to the outlet <NUM> of the evaporative spiral plate heat exchanger <NUM>. The first channel <NUM> and the second channel <NUM> extend substantially in parallel to each other.

Further, the evaporative spiral plate heat exchanger <NUM> may be oriented such that a center axis of the evaporative spiral plate heat exchanger <NUM> is along a vertical axis of the WSAC <NUM>, and a radial axis of the evaporative spiral plate heat exchanger <NUM> is along a horizontal axis of the WSAC <NUM>.

A spiral plate heat exchanger normally includes two spiral sheets extending along a respective spiral-shaped path around the center axis and forming the first channel and the second channel, which are substantially parallel to each other. Distance members, having a height corresponding to the width of the flow channels, may be attached to at least one of the sheets, typically welded to at least one of the sheets, to separate the sheets, obtain a desired distance between the sheets and give rigidity to the spiral plate heat exchanger, in particular to a spiral body of the spiral plate heat exchanger.

The spiral plate heat exchanger <NUM> includes at least one spiral sheet <NUM> wound to form the first channel <NUM>. The wound at least one spiral sheet <NUM> also forms the second channel <NUM>.

The wound at least one spiral sheet <NUM> separates the first channel <NUM> and the second channel <NUM>.

The spiral plate heat exchanger <NUM> includes a spiral body <NUM> formed by the wound at least one spiral sheet <NUM>. Distance members (not shown), e.g. studs, typically cylindrical studs, may be attached to said at least one sheet <NUM> to separate the windings of said at least one sheet <NUM>.

The spiral plate heat exchanger <NUM> includes a spiral body <NUM>. The spiral body <NUM> is formed by at least one spiral sheet <NUM> wound to form the spiral body <NUM>. The spiral body <NUM> forms a spiral-shaped first channel <NUM> and a spiral-shaped second channel <NUM>.

The spiral body <NUM> is typically formed by two spiral sheets <NUM> of metal wound to form the spiral-shaped first channel <NUM> and the spiral-shaped second channel <NUM>. Alternatively, the spiral body <NUM> may be formed from a single sheet <NUM> of metal providing two sheet portions extending from the center of the spiral body <NUM> and wound to form the spiral body <NUM>. The spiral body <NUM> may be formed in a conventional way by winding two sheets <NUM> of metal around a retractable mandrel, but it can also be formed in other ways. In the figures, the spiral body <NUM> only has been schematically shown with a number of windings, but it is obvious that it may include further windings and that the windings are formed from the center of the spiral body <NUM> all the way out to the periphery of the spiral body <NUM>. When the at least one spiral sheet <NUM> is wound windings are formed, more precisely, a plurality of windings are formed.

The spiral body <NUM> is enclosed by a substantially cylindrical shell <NUM>. The spiral body <NUM> may be enclosed by a separate shell <NUM> (as shown in <FIG>), or alternatively the sheets <NUM> forming the spiral body may also constitute the shell <NUM> by the outer winding of the sheet <NUM> (as shown in <FIG>). The spiral body <NUM> comprises a center body <NUM>, which typically is cylindrical. The center body <NUM> may be formed by a center portion of the sheet(s), or by a cylindrical center piece. The center body <NUM> of the spiral plate heat exchanger is covered by center covers <NUM>, which is welded onto the spiral body <NUM>, more precisely at each end, i.e. the top and bottom ends, of the center body <NUM>.

The center body <NUM> of the spiral body <NUM> may be formed by a cylindrical piece on which an end of each spiral sheet <NUM> is welded. Alternatively, the center body <NUM> of the spiral body <NUM> may be formed by inserting an end of each of the two sheets <NUM> of metal into opposite slits of the retractable mandrel as described in <CIT>, which is incorporated herein by reference. As a further alternative, the starting material for the spiral body <NUM> may be a single sheet <NUM>, where a central portion of the single sheet <NUM> is inserted in a mandrel and two sheet portions extending from the central portion are wound to form the spiral body <NUM> as well as the center body <NUM>. The winding machine winds the sheets <NUM> to form the spiral body <NUM>. After the winding machine has completed the winding of the sheets <NUM> of metal, the spiral body <NUM> is removed from the winding machine and the retractable mandrel is removed. The spiral body <NUM> is then moved to a welding station for manually or by a welding machine seal or close up the first channel <NUM> and the second channel <NUM> from each other by welding together the edges, i.e. the top and bottom edges, of the windings of the sheets <NUM> to each other such that the first channel <NUM> is closed and the second channel <NUM> is open at the top and bottom. This is done by closing every second winding opening by welding. The center covers <NUM> are welded onto each end opening of the center body <NUM> to achieve a resistant and sealed center body <NUM>.

The sheet <NUM> is a plate that is sufficiently flexible to enable winding of the plate into a spiral shape. However, a winding machine may be needed to achieve the winding of the sheet/plate into a spiral shape.

As illustrated in <FIG>, shown by the arrows, the evaporative spiral plate heat exchanger <NUM> has a cross-flow arrangement in which the direction of air and/or cooling medium flowing through the second channels <NUM> is cross or perpendicular to the direction of the process medium flowing through the first channel <NUM>.

The evaporative spiral plate heat exchanger <NUM> may include a header connected to the outlet <NUM>, as shown in <FIG>, or may be provided without a header, as shown in <FIG>, <FIG>, <FIG> and <FIG>.

The evaporative spiral plate heat exchanger <NUM>, including the first channel <NUM> or more precisely the at least one sheet <NUM> forming the first channel <NUM>, may be comprised of a metal material, with good thermal conductivity, such as stainless steel, copper, galvanized steel, any other known material. Further, the first channel <NUM> may radiate heat (i.e., conduct heat) away from the process medium toward the second channels <NUM>. Further, the cooling medium sprayed onto the evaporative spiral plate heat exchanger <NUM> is coated along an entire length (i.e., axial length) of the second channels <NUM> to further conduct heat away from the process medium. Due to the construction of the evaporative spiral plate heat exchanger <NUM> with a vertical channel (second channels <NUM>), it allows for a heat exchanger design making optimal use of the available pressure drop while allowing maximum exposure of the airflow and cooling medium to the heat transfer surface, thus improving the thermal dissipation effect of the evaporative spiral plate heat exchanger <NUM>.

A process medium (e.g., hot process medium) flows through the evaporative spiral plate heat exchanger <NUM> by a means known in the art. In the present invention, the process medium flow through the inlet <NUM>, through the first channel <NUM>, and out of the outlet <NUM>. The process medium may be any type of hot process medium as known in the art, such as water, glycol, oil, fuel, gasses or the like, or for condensing steam, ammonia, propylene, butane, or the like.

Further, as shown in <FIG>, an inlet connection may extend from outside of the WSAC <NUM>, to the cross-sectional center of the evaporative spiral plate heat exchanger <NUM> and an outlet connection may extend from an outer extent (i.e., outermost radial extent) of the WSAC <NUM>.

<FIG> illustrates the evaporative spiral plate heat exchanger <NUM> oriented vertically (i.e., in a height direction), in the same manner as shown in <FIG> and <FIG>, such that air flows axially through the evaporative spiral plate heat exchanger <NUM>, which is caused by the fan <NUM>.

That is, the process medium flows from the inlet <NUM> located at a cross-sectional center of the evaporative spiral plate heat exchanger <NUM> radially outwardly in a spiral manner to the outlet <NUM>, which may be provided at a circumference or outermost radial surface of the evaporative spiral plate heat exchanger <NUM>. The second channels <NUM> are located between each wind (e.g., turn) of the first channel <NUM>, to permit airflow around each wind of the first channel <NUM>. That is, the second channels <NUM> are axial channels that extend in an axial direction (i.e., vertical direction) of the WSAC <NUM> (and likewise an axial/vertical direction of the evaporative spiral plate heat exchanger <NUM>). The second channels <NUM> (or set of second channels <NUM>) may be formed by a single continuous spiral channel <NUM> extending axially through the evaporative spiral plate heat exchanger <NUM>, in which each of the second channels <NUM> may be connected to one another. That is, each portion of the second channel within a respective wind of the first channel may be construed as one of the plurality of second channels.

Alternatively, an outlet connection may extend from outside of the WSAC <NUM>, to the cross-sectional center of the evaporative spiral plate heat exchanger <NUM>, and an inlet connection may extend from an outer extent of the WSAC <NUM>. That is, process medium may flow from the inlet <NUM> located at an outermost radial extent of the evaporative spiral plate heat exchanger <NUM> radially inwardly in a spiral manner to the outlet <NUM>, the outlet <NUM> being positioned at a radial center of the evaporative spiral plate heat exchanger <NUM>. The second channels <NUM> are located between each wind (e.g., turn) of the first channel <NUM>, to permit airflow around each wind of the first channel <NUM>.

Airflow generated by the fan may flow from outside of the WSAC <NUM> through the one or more airflow passages <NUM>, through the second channels <NUM>, and out through the first passage <NUM>. That is, the fan <NUM> may pull air through the WSAC <NUM>. Alternatively, the fan <NUM> may push air through the WSAC <NUM> by pushing air in from the first passage <NUM>, through the evaporative spiral plate heat exchanger <NUM>, and out through the one or more airflow passages <NUM> of the lower module.

The combination of the sprayed cooling medium onto the evaporative spiral plate heat exchanger <NUM> (i.e., the second channels <NUM>), and the airflow through the second channels <NUM> of the evaporative spiral plate heat exchanger <NUM> causes the cooling medium on the second channels <NUM> evaporate, which further increases the thermal conductivity of the evaporative spiral plate heat exchanger <NUM>. That is, the evaporative spiral plate heat exchanger <NUM> is exposed to cooling medium sprayed thereon by the spray system <NUM>, vapor in the form of evaporated cooling medium, and airflow via the fan <NUM> through the airflow passages <NUM>.

The spray system <NUM> of the present invention keeps a surface (i.e., vertical surface) of the second channels <NUM> coated with the cooling medium (i.e., wet) to improve the wetting of the evaporative spiral plate heat exchanger <NUM> and thus the cooling effect from the spray system <NUM>.

This evaporative effect of the present invention improves the dissipation of heat from the process medium, thereby improving the efficiency of the WSAC <NUM>. Due to the improved thermal efficiency, the WSAC <NUM> according to the present invention can have a reduced footprint (i.e., a reduced diameter). Further, the vertically stacked configuration of the WSAC <NUM>, including the circular cross section for the upper module <NUM>, the lower module <NUM> and the evaporative spiral plate heat exchanger <NUM> according to the present invention, results in a reduced pressure loss on the fan side of the WSAC <NUM> (i.e., at the first passage <NUM>, to enhance the efficiency of the WSAC <NUM>).

That is, the spiral shape of the evaporative spiral plate heat exchanger <NUM> allows airflow axially therethrough (i.e., through the second channels <NUM>) and cooling medium to be sprayed thereon to contacts an entire axial length of each second channel <NUM>. The contact of water with the entire axial length of the second channel <NUM> improves the cooling effect of the process medium.

<FIG> and <FIG> are directed to an alternate embodiment of the present invention in which the fan <NUM> is spaced apart in a horizontal direction from the spray system <NUM>, and each of the fan <NUM> and the spray system <NUM> are mounted onto the lower housing <NUM> comprising the basin <NUM>.

The embodiment of <FIG> and <FIG> also includes the evaporative spiral plate heat exchanger <NUM> with the same structure and orientation as shown in <FIG>. Further, the embodiment of <FIG> and <FIG> operates in a similar manner to the embodiment of <FIG>, with the difference mainly being the location of the fan <NUM> relative to the evaporative spiral plate heat exchanger <NUM>.

Further, instead of having air passages, the embodiment of <FIG> and <FIG> includes a second passage <NUM> positioned at a top surface of the spray system <NUM>, in order to introduce air into the WSAC <NUM> or to expel air out of the WSAC <NUM>.

As in the embodiment of <FIG> and <FIG>, cooling medium collected in the basin <NUM> of the lower module <NUM> is pumped, by the pump <NUM>, back to the spray system <NUM> via the first and second fluid lines <NUM>, <NUM>.

The WSAC <NUM> of <FIG> and <FIG> can operate in a counter-current arrangement, in which the fan <NUM> draws in air through the first passage <NUM>, down and across the basin <NUM>, upwards through the evaporative spiral plate heat exchanger <NUM>, and out through the second passage <NUM>. That is, the upward direction of airflow through the evaporative spiral plate heat exchanger <NUM> is counter to the downward direction of cooling medium sprayed by the distribution channels <NUM>.

Alternatively, in a co-current arrangement of the present invention, the fan <NUM> pulls air through the second passage <NUM>, down through the evaporative spiral plate heat exchanger <NUM>, across the basin <NUM> and out through the first passage <NUM>. That is, the downward direction of airflow through the evaporative spiral plate heat exchanger <NUM> is co-current with to the direction of cooling medium sprayed by the distribution channels <NUM>.

The embodiment of <FIG> and <FIG> works in a similar manner to that of <FIG> above, in that the combination of the sprayed cooling medium onto the evaporative spiral plate heat exchanger <NUM> (i.e., the second channels <NUM>), and the airflow through the second channels <NUM> of the evaporative spiral plate heat exchanger <NUM> causes the cooling medium on the second channels <NUM> evaporate, which further increases the thermal conductivity of the evaporative spiral plate heat exchanger <NUM>. This evaporative effect improves the dissipation of heat from the process medium, thereby improving the efficiency of the WSAC <NUM>. Due to the improved thermal efficiency of the WSAC <NUM> according to the present invention can have a reduced footprint.

The spray system <NUM> may be removably coupled to a top surface of the evaporative spiral plate heat exchanger <NUM>, as shown in <FIG> and <FIG>. Further, the evaporative spiral plate heat exchanger <NUM> may be removably coupled to a top surface of a lower housing <NUM> comprising the basin <NUM>. Similarly, the fan <NUM> may be removably coupled to the top surface of the lower housing <NUM> and may be horizontally spaced from the evaporative spiral plate heat exchanger <NUM>.

Similar to that of <FIG> above, the embodiment of <FIG> and <FIG> may also be modular. The fan <NUM> may be a first module and the evaporative spiral plate heat exchanger <NUM> or the combination of the evaporative spiral plate heat exchanger <NUM> with the spray system <NUM> may be as second module, and the basin may be a third module. The first module, second module, and third module may be replaced with another module having different flow characteristics, including a module having a different configuration, such as a different height, a different fan size, and/or a different shape, as known in the art.

As set forth above with respect to the upper module <NUM>, lower module <NUM> and the evaporative spiral plate heat exchanger <NUM>, the first module, the second module and the third module may be provided with flanges to allow for connection between the first module, the second module and the third module. In case the spiral plate heat exchanger comprises a shell <NUM>, the shell <NUM> of the spiral plate heat exchanger <NUM> may be provided with flanges.

The present invention is not limited to the examples shown in <FIG>, and may have different shapes and configurations.

Claim 1:
A wet surface air cooler (WSAC) (<NUM>), comprising:
an evaporative spiral plate heat exchanger (<NUM>) including a first channel (<NUM>) configured to receive a process medium;
a spray system (<NUM>) configured to spray a cooling medium onto the evaporative spiral plate heat exchanger (<NUM>); and
a fan (<NUM>) configured to force air to flow through the evaporative spiral plate heat exchanger (<NUM>),
wherein the combination of the sprayed cooling medium onto the evaporative spiral plate heat exchanger (<NUM>) and the air flowing through the evaporative spiral plate heat exchanger (<NUM>) causes the cooling medium to at least partially evaporate to cause a temperature of the process medium to decrease.