Patent Description:
Typically, the cost of fill media can be reduced by creating a fill media product of adequate thermal performance for a given cooling tower application, which consists of fewer individual sheets to construct the fill media assembly. This reduction in sheets per unit fill volume results in a material savings and lower fill pack forming and assembly times, thereby lowering the overall product cost.

The performance of a cooling tower is usually measured by the quantity of water that the tower can cool to a specified operating temperature at specified design conditions. Most of this cooling takes place in the fill media where the water flowing through the fill media mixes with the air flowing through the fill media. The main form of heat transfer from the water to the surrounding air is though evaporation. A small quantity of water evaporates from the bulk water in the tower. This evaporating mass of water carries with it the energy equal to the heat of vaporization from the bulk water, causing the remaining water to cool. It is commonly understood that having a larger surface area within the fill media increases the rate of evaporation. Hence, a fill with more surface area per unit volume is typically more effective at cooling water flowing though the fill media or fill pack compared to a fill media or fill pack with less surface area per unit volume.

Evaporation of water into the air is limited by the moisture carrying capacity of the air. As air becomes more saturated with water vapor, the evaporation rate decreases. This means that to maintain a high rate or degree of evaporation, a high mass flow rate of air through the tower and fill media is required. In cooling towers, this is usually accomplished with the help of fans or by forcing air through the fill media or fill packs, although natural draft systems are based on currents created by a difference in air density inside and outside the tower. The air driven by the fan in the typical tower faces resistance to its motion as the forced air flows through spaces or channels within the fill media or fill packs. This resistance can be characterized by a resulting pressure drop across the fill media as the air flows from an entrance side of the fill media to an exit side of the fill media. Overcoming a relatively large pressure drop in the fill media generally requires use of a fan with a higher power when compared to a more modest pressure drop. The job of an effective fill pack is to achieve the specified cooling effect with as little pressure drop as possible. In other words, a preferred pack has high thermal performance and low pressure drop values between the air entrance side and the air exit side.

A fill media or fill pack is generally comprised of an assembly of corrugated sheets that are connected to form the fill media or fill pack. The large primary corrugations in the corrugated sheets are referred to as "flutes" or macrostructure. The flutes in a sheet increase the surface area of the sheet on which water can form a film, thereby increasing the surface area of water that is exposed to the air flowing through the corrugations or flutes. The flutes also form a channel for the air that flows though the fill pack along the flutes from an intake end to an exit end of the fill media or fill packs. For example, a flute angled at thirty degrees (<NUM>°) from a straight flow direction between the intake and exit ends, which may be a vertical direction/axis, typically in a cross-fluted fill pack, of the fill media or fill pack will cause the air to flow generally in the same direction as the flute or to generally follow along and through the flute, guided by the flute. This means that the flute geometry has an impact on the way the air flows through the pack. This feature of the flutes can be used not only to direct air where needed, but also to increase mixing of the air stream within a pair of flutes and within the fill pack; thereby avoiding stratification or channeling of the air.

Microstructure is typically added to the flutes to further increase the surface area of the fill media or fill pack upon which the water can form a film for interaction with the air flowing through the flutes. Microstructure in the flutes also keeps the film of water that flows down a flute in a state of constant flux or change such that the film of water that is closely exposed to the flowing air constantly changes to improve heat transfer. The constant mixing of the water film resulting from the microstructure increases the rate of cooling of the liquid film similar to the way stirring hot coffee cools the coffee down faster than leaving it unstirred. The microstructure also serves to maintain distribution of the water on the surface to provide a benefit for all of the available surface area provided by the flute and macrostructure geometry.

<CIT> may disclose a fill sheet for insertion into a counterflow cooling tower, wherein the fill sheet is oriented such that air flows along a plurality of flutes from an intake edge toward an air exit edge and water flows from the air exit edge toward the air intake edge to cool a cooling medium flowing over the sheet, the fill sheet comprising the air intake edge; the air exit edge positioned opposite the air intake edge the plurality of flutes extending from the air intake edge toward the air exit edge, an airflow axis extending through the air intake edge and the air exit edge and a lateral axis extending substantially perpendicular to the airflow axis, the plurality of flutes including a first flute section having a first peak, a first inlet end, a first outlet end and defining a first flute vector; and microstructure formed on the plurality of flutes, the microstructure defining a microstructure angle of zero to <NUM> degrees relative to the lateral axis, the microstructure including the first peak between the first inlet end and the first outlet end on the first flute section, the microstructure serving to redistribute the water both within and between the plurality of flutes by generating water flow in a direction of micro-corrugations of the microstructure, the microstructure angle being independent of the first flute vector.

Incorporating flutes and microstructures in the flutes of a fill pack, however, may cause an undesired effect of increasing the resistance to the air flow, thereby increasing pressure drop between the entrance or intake end and the exit end of the fill pack. It would be desirable to design, develop and deploy fill sheets assembled into fill packs that improve thermal efficiency and limit pressure drop in the typical operating conditions of a cooling tower. The preferred present invention addresses shortcomings of prior art fill sheets and related fill pack assemblies by arranging the fill sheets in the fill packs relative to each other to improve the heat transfer between the water flowing through the fill packs and the air flowing along the flutes.

Further preferred embodiments are described by the dependent claims. A preferred embodiment of the present invention is directed to a fill sheet for insertion into a cooling tower to cool a cooling medium flowing over the sheet. The fill sheet includes an air intake edge, an air exit edge positioned opposite the air intake edge and a plurality of flutes extending from the air intake edge toward the air exit edge. An airflow axis extends through the top edge and the bottom edge and a lateral axis extends substantially perpendicular to the airflow axis. The plurality of flutes includes a first flute section. The first flute section includes a first arc extending at a first side of the airflow axis and a second arc extending at a second opposite side of the airflow axis. The fill sheet also includes a plurality of spacer rows. The spacer rows include an air intake spacer row and an intermediate spacer row. The air intake spacer row is positioned at the air intake edge and the intermediate spacer row is positioned between the first arc and the second arc. The fill sheet also includes microstructure formed on the plurality of flutes. The microstructure defines a microstructure angle relative to the lateral axis.

The foregoing summary, as well as the following detailed description of the preferred invention, will be better understood when read in conjunction with the appended drawings. For the purpose of illustrating the preferred invention, the drawings show embodiments which are presently preferred. It should be understood, however, that the invention is not limited to the precise arrangements and instrumentalities shown. In the drawings:.

Certain terminology is used in the following description for convenience only and is not limiting. Unless specifically set forth herein, the terms "a", "an" and "the" are not limited to one element but instead should be read as meaning "at least one". The words "right," "left," "lower," and "upper" designate directions in the drawings to which reference is made. The words "inwardly" or "distally" and "outwardly" or "proximally" refer to directions toward and away from, respectively, the geometric center or orientation of the device and instruments and related parts thereof. The terminology includes the above-listed words, derivatives thereof and words of similar import.

It should also be understood that the terms "about," "approximately," "generally," "substantially" and like terms, used herein when referring to a dimension or characteristic of a component of the invention, indicate that the described dimension/characteristic is not a strict boundary or parameter and does not exclude minor variations therefrom that are functionally the same or similar, as would be understood by one having ordinary skill in the art. At a minimum, such references that include a numerical parameter would include variations that, using mathematical and industrial principles accepted in the art (e.g., rounding, measurement or other systematic errors, manufacturing tolerances, etc.), would not vary the least significant digit.

Referring to <FIG>, <FIG>, <FIG>, a first preferred embodiment of the present invention is directed to a fill sheet, generally designated <NUM>, constructed of a relatively thin polymeric material for assembly into fill media or fill packs, generally designated <NUM>', of a cooling tower. The first preferred fill sheet <NUM> is not shown in the drawings assembled into fill media or fill packs, although the first preferred fill sheets <NUM> is generally assembled into fill media or fill packs similarly to the second preferred fill media or fill packs <NUM>', as would be apparent to one having ordinary skill in the art based on a review of the present disclosure. The fill sheets <NUM> define a plurality of flutes or corrugations <NUM>, which comprise part of the macrostructure of the first preferred fill sheets <NUM>, including a first sheet flute 12a, a second sheet flute 12b, a third sheet flute 12c, a fourth sheet flute 12d, a fifth sheet flute 12e and a sixth sheet flute 12f that extend from an air exit edge <NUM> to an air intake edge <NUM> of the fill sheet <NUM>. In the first preferred embodiment, the sheet flutes <NUM> are interrupted by spacer rows <NUM> that extend across the fill sheets <NUM>, generally perpendicular relative to an airflow axis <NUM> that extends between the air exit and intake edges <NUM>, <NUM>. The spacer rows <NUM> provide plateaus <NUM> where adjacent fill sheets <NUM> meet or are spaced relative to each other in an assembled in installed configuration, as will be described in greater detail below.

The sheet flutes 12a, 12b, 12c, 12d, 12e, 12f have generally the same or a similar configuration within the fill media or fill pack and are described herein generically as flutes <NUM>. There are preferably six (<NUM>) sheet flutes <NUM> per foot on each side of the fill sheet <NUM> in the first preferred embodiment, although the fill sheet <NUM> is not so limited. The fill sheet <NUM> is not limited to including six (<NUM>) sheet flutes <NUM> and may include more or less sheet flutes <NUM> depending on the preferred size and shape of the fill sheet <NUM>, the size of the cooling tower, designer preferences and other related factors. The first preferred fill sheets <NUM> and fill media or fill packs constructed of pluralities of assembled or installed fill sheets <NUM> are configured and designed for use in a counterflow cooling tower, wherein the air flows along the sheet flutes <NUM> from the air intake edge <NUM> toward the air exit edge <NUM> in an airflow direction <NUM> and water flows under the force of gravity from the air exit edge <NUM> toward the air intake edge <NUM> in a water flow direction <NUM>. The fill sheets <NUM> and fill packs, including their herein described features, are not limited to use in counterflow cooling towers or in counterflow usage and may be employed in crossflow cooling towers or other related flow applications.

Referring to <FIG>, in a second preferred embodiment a fill sheet <NUM>' and related fill media or fill packs <NUM>' have a similar configuration and function when compared to the first preferred fill sheets <NUM> and fill packs and the same reference numerals are utilized to identify the same or similar features, with a prime symbol (') utilized to distinguish the second preferred embodiment from the first preferred embodiment. The second preferred fill sheets <NUM>' and fill media or fill packs <NUM>' are designed and configured for use in counterflow cooling towers, but include additional spacer rows <NUM> and are shown without microstructure <NUM> thereon, although the second preferred fill sheets <NUM>' are similarly designed and constructed when compared to the first preferred fill sheets <NUM> and may include microstructure <NUM> thereon, as is shown in <FIG>. The fill sheets <NUM>' and fill media or fill packs <NUM>' of the second preferred embodiment, including their herein described features, are not limited to use in counterflow cooling towers and may be employed in crossflow cooling towers or other related flow applications.

Referring to <FIG>, the first and second preferred fill sheets <NUM>, <NUM>' are assembled into the fill media or fill packs <NUM>' by positioning the spacer rows <NUM>, <NUM>' adjacent to each other, such as by hanging the sheets <NUM>, <NUM>' next to each other, bonding the mating spacer rows <NUM>, <NUM>' together, engaging connections <NUM>, <NUM>' along the spacer rows <NUM>, <NUM>' of adjacent fill sheets <NUM>, <NUM>' to secure and lock the adjacent sheets <NUM>, <NUM>' together or otherwise position the fill sheets <NUM>, <NUM>' to define the fill media or fill packs <NUM>'. The fill sheets <NUM>, <NUM>' are not limited to inclusion of the connections <NUM>, <NUM>', which are preferably crushed together to attach the fill sheets <NUM>, <NUM>' together, and may be comprised of glue bosses, spacers, alignment features, snap-fit connections or other spacers or connectors that are able to position the fill sheets <NUM>, <NUM>' relative to each other to define the fill packs <NUM>'. For example, the fill sheets <NUM>, <NUM>' may include blunt spacers (See plateaus <NUM>' of <FIG>) that do not connect to each other, but space the fill sheets <NUM>, <NUM>' relative to each other in the general configuration of the fill pack <NUM>' or are glued together to define the fill media or fill pack <NUM>'. <FIG> and <FIG> disclose a preferred fill media or fill pack <NUM>' with first and second fill sheets 10a', 10b'. The fill media or fill packs <NUM>' may be constructed of nearly any number of fill sheets <NUM>, <NUM>' to produce fill media or fill packs <NUM>' having various sizes.

A flute geometry of the flutes <NUM>, <NUM>' includes a flute profile of varying height following a path formed by a series of connected tangent arcs, each of which have a midpoint which extends horizontally by less than one-half (½) the flute period from the arc ends. All arc endpoints for the flute path of the flutes <NUM>, <NUM>' are aligned vertically and provide a location for the spacer rows <NUM>, <NUM>', spacers and/or connections <NUM>, <NUM>' between adjacent fill sheets <NUM>, <NUM>'. The arcs on each adjacent, overlying/underlying fill sheet <NUM>, <NUM>' of the fill media or fill packs <NUM>' curve in opposite directions from the spacer rows <NUM>, <NUM>' or connections <NUM>, <NUM>' when the fill sheets <NUM>, <NUM>' are assembled into the fill media or fill pack <NUM>', thereby creating a separation between the peaks 36c, 36c' of the flutes <NUM>, <NUM>' between the spacer rows <NUM>, <NUM>' or connections <NUM>, <NUM>', allowing for the flute height of the fill sheet <NUM>, <NUM>' to be increased toward the arc center. For example, the first and second sheet flutes 12a, 12a', 12b, 12b' of the first fill sheet 10a, 10a' include first and second peaks 36c, 36c', 38c, 38c' that have increased heights between the spacer rows <NUM>, <NUM>' along the first and second peaks 36c, 36c', 38c, 38c' (See <FIG>).

The geometry of the assembled preferred sheet flutes <NUM>, <NUM>' described above forms the fill media or fill packs <NUM>' that mix the air within a flute airflow portion <NUM>' defined by each of the sheet flutes <NUM>, <NUM>' between an airflow inlet end 36a, 36a', an airflow outlet end 36b, 36b', the flute peak 36c, 36c' and the opposite valleys 36d, 36d', 36e, 36e' associated with the flute peak 36c, 36c'. The airflow inlet end 36a, 36a' and airflow outlet end 36b, 36b' of the flute airflow portions <NUM>' are positioned at the spacer rows <NUM>, <NUM>' in the first and second preferred embodiments and each pair of fill sheets <NUM>, <NUM>' in the fill media or fill pack <NUM>' include pluralities of flute airflow portions <NUM>' associated with each of the sheet flutes <NUM>, <NUM>'. The configuration of the sheet flutes <NUM>, <NUM>' and their assembly into the fill media and fill packs <NUM>' to define the flute airflow portions <NUM>' mix the flowing air and the cooling fluid, namely water, by continually changing cross-sectional shape within the flute airflow portions <NUM>' and by the water film on the fill sheets <NUM>, <NUM>' interacting with the air as the air flows through the flute airflow portions <NUM>'. In addition, the small, alternating horizontal offset of the arc of the sheet flutes <NUM>, <NUM>' allows for increased flute height at the peaks 36c, 36c', 38c, 38c' away from the arc's ends near the spacer rows <NUM>, <NUM>' and connections <NUM>, <NUM>' of the first and second preferred embodiments. The offset of the arc of the sheet flutes <NUM>, <NUM>' increases the surface area of the fill sheets <NUM>, <NUM>' and thermal performance, while still maintaining a nearly vertical geometry of the sheet flutes <NUM>, <NUM>' with minimal contact points, which is desirable for a low fouling fill design. Mass transfer occurs within the flute airflow portions <NUM>' and sheet flutes <NUM>, <NUM>', such as between the first and second sheet flutes 12a, 12a', 12b, 12b' of the fill media or fill pack <NUM>', because of differences in partial pressure between the air in contact with the fluid surface area and the saturated condition. The air in contact with the fluid surface area on the fill sheets <NUM>, <NUM> is refreshed with less saturated air from the bulk air flow as the air flows through the pluralities of flute airflow portions <NUM>' as a result of the preferred geometry of the sheet flutes <NUM>, <NUM>', the fill sheets <NUM>, <NUM>' and the fill packs <NUM>'. Because of the velocity of the air flow in the airflow direction <NUM>, <NUM>' (as much as <NUM> feet per minute), the air flow through the sheet flutes <NUM>, <NUM>' is likely turbulent, however, stratification of humid air can still exist within the flutes <NUM>, <NUM>'.

The air is typically in the fill pack <NUM>' between the air intake edge <NUM>' and the air exit edge <NUM>' for about one-half a second (<NUM>/<NUM> sec) based on air travel distance in the fill media or fill pack <NUM>' and air velocity. The continuous change in the shape of the cross-section of the preferred flute airflow portions <NUM>' of the assembled sheet flutes <NUM>, <NUM>' and the cross-sections along the flute portions <NUM>' disrupts the boundary layers of the flowing air or stratification that can exist in the air flow. As the air flows through the continuously changing cross-sectional shape the flute portions <NUM>', the small changes in directional flow of the air has an impact on the mass transfer by refreshing the boundary layer and improving mixing with the bulk phase. As the fluid travels down the surfaces of the fill sheets <NUM>, <NUM>' through the continuously varying flute airflow portions <NUM>', at least portions of the air flowing through the flute airflow portions <NUM>' passes over the peaks 36c, 36c', 38c, 38c' of the flutes <NUM>, <NUM>' into adjacent flute airflow portions <NUM>'.

Referring to <FIG>, <FIG> and <FIG>, a simplified representation of the shape and configuration of the first and second peaks 36c', 38c' of the first and second sheet flutes 12a', 12b' of the first and second fill sheets 10a', 10b' in the fill pack <NUM>' show tangent points where the peaks 36c', 38c', generally overlie each other along the air flow axis <NUM>'. This configuration facilitates the above-described mixing of air in the sheet flutes <NUM>' and the flute portions <NUM>' by promoting not only the air following a single sheet flute <NUM>' from the air intake edge <NUM>' to the air exit edge <NUM>', but flow of the air over the peaks 36c', 38c'and into adjacent sheet flutes <NUM>' or flute portions <NUM>', thereby further facilitating mixing of the air at the surfaces of the fill sheets <NUM>' within the fill media or fill pack <NUM>'.

Referring to <FIG>, the fill sheets <NUM>, <NUM>' also include microstructure <NUM>, <NUM>' incorporated thereon primarily to disturb the water film as it flows through the fill pack <NUM>', aid in the distribution of water on the fill sheet <NUM>, <NUM>' within the sheet flute <NUM>, <NUM>' and the flute airflow portions <NUM>' and to increase the total surface area exposure of the film of water on the microstructure <NUM>, <NUM>' to the air flowing through the fill pack <NUM>'. The fill sheets <NUM>, <NUM>' and fill media or fill packs <NUM>' of <FIG> of the second preferred embodiment, except for <FIG>, do not show the microstructure <NUM>, <NUM>' on the surfaces of the fill sheet <NUM>, <NUM>', although the first and second preferred fill sheets <NUM>, <NUM>' include the microstructure <NUM>, <NUM>' and the microstructure <NUM>, <NUM>' is not shown in these views for simplicity. The most common type of microstructure <NUM>, <NUM>' can be described as bands or small corrugations which are cut out of the larger cycles of the fill sheets <NUM>, <NUM>' and sheet flutes <NUM>, <NUM>' (or macrostructure). In the preferred fill media and fill packs <NUM>', the microstructure <NUM>, <NUM>' is preferably comprised of arcuate, trapezoidal or sinusoidal bands of microstructure <NUM>, <NUM>' that are formed in a direction that is at an angle independent of the path or direction of the macrostructure's sheet flutes <NUM>, <NUM>' as is particularly shown in <FIG> and <FIG>. The preferred microstructure <NUM>, <NUM>' is generally designed and configured independently from the macrostructure, corrugations or sheet flutes <NUM>, <NUM>' of the preferred fill sheets <NUM>, <NUM>' in that the microstructure <NUM>, <NUM>' of the first and second preferred embodiments has a Chevron or herringbone shape that extends at a microstructure angle Δ relative to the sheet flutes <NUM>, <NUM>' as opposed to the typical microstructure of the prior art, which generally extends perpendicular to the flutes of fill sheets or perpendicular to the airflow axis <NUM>.

The microstructure <NUM>, <NUM>' of the first and second preferred fill sheets <NUM>, <NUM>' is comprised of corrugated bands formed into the sheet flutes <NUM>, <NUM>' or fill sheets <NUM>, <NUM>' at the microstructure angle Δ. The microstructure angle Δ is independent of the direction of travel or path of the sheet flutes <NUM>, <NUM>' between the air intake edge <NUM>, <NUM>' and the air outlet edge <NUM>, <NUM>' to redistribute the water film both within and between the sheet flutes <NUM>, <NUM>' by generating water flow in the direction of the micro-corrugations of the microstructure <NUM>, <NUM>'. This configuration of the microstructure <NUM>, <NUM> 'provides a benefit over known microstructure orientations, as less aggressive (shorter) microstructure is required to distribute water across the preferred fill sheets <NUM>, <NUM>', leading to lower pressure drop and better fouling resistance. The first and second preferred microstructure <NUM>, <NUM>' substantially defines the Chevron or herringbone design between upper and lower portions 11a, 11a', 11b, 11b' of the fill sheets <NUM>, <NUM>'. The microstructure angle Δ is approximately thirty degrees (<NUM>°) in the preferred embodiments, but is not so limited and may be larger or smaller, such as between fifteen and forty-five degrees (<NUM>-<NUM>°) depending on design preferences, requirements and other factors. The microstructure angle Δ is measured between a lateral axis <NUM>, <NUM>' defined on the upper and lower portions 11a, 11a', 11b, 11b' and the longitudinal path of the microstructure <NUM>, <NUM>'. The lateral axis <NUM>, <NUM>' is perpendicular to the airflow axis <NUM>, <NUM>'.

The first and second preferred fill sheets <NUM>, <NUM>' define a sheet plane <NUM>, <NUM>' that are preferably defined by plateaus <NUM>, <NUM>' from which the projections <NUM>, <NUM>' may or may not extend, generally at the spacer rows <NUM>, <NUM>'. In the first and second preferred embodiments, at least portions of the sheet flutes <NUM>, <NUM>' between adjacent spacer rows <NUM>' arc beyond the sheet plane <NUM>, <NUM>' at the peaks 36c, 36c', 38c, 38c' of the sheet flutes <NUM>, <NUM>' away from a central portion of the fill sheet <NUM>, <NUM>' at an offset distance D, D'. The sheet flutes <NUM>, <NUM>' also preferably have a flute cycle CF, CF' of approximately one and one-half to four inches (1½-<NUM>") or three and eight tenths centimeters to ten centimeters (<NUM>-<NUM>), but these specific flute cycles CF, CF' are not so limited and may be otherwise sized and configured. The microstructure <NUM>, <NUM>' preferably has a microstructure height HM, HM' of approximately four hundredths to one tenth of an inch (<NUM>. -<NUM>-<NUM> ") or one to two and one-half millimeters (<NUM>-<NUM>), but is not so limited and may be otherwise sized and configured. The fill sheets <NUM>, <NUM>' in the fill packs <NUM>' are preferably spaced or define a sheet spacing HS' of approximately three-quarters of an inch to one and two tenths of an inch (¾-<NUM>") or one and nine tenths to three centimeters (<NUM>-<NUM>), but is not so limited and may be otherwise sized and configured.

Referring to <FIG>, in a third preferred embodiment a fill sheet <NUM>" and related fill packs <NUM>' have a similar configuration and function when compared to the first and second preferred fill sheets <NUM>, <NUM>' and fill packs <NUM>' and the same reference numerals are utilized to identify the same or similar features, with a double-prime symbol (") utilized to distinguish the third preferred embodiment from the first and second preferred embodiments. The third preferred fill sheets <NUM>" and fill media or fill packs <NUM>" are designed and configured for use in crossflow cooling towers, wherein the air flows along the sheet flutes <NUM>" and within the flute airflow portions <NUM>" from an air intake edge <NUM>" toward an air exit edge <NUM>" in an airflow direction <NUM>" and water flows under the force of gravity from a top edge <NUM> of the fill sheets <NUM>" toward and out of a bottom edge <NUM> of the fill sheets <NUM>" in a water flow direction <NUM>". The fill sheets <NUM>" and fill media or fill packs <NUM>" of the third preferred embodiment, including their herein described features, are not limited to use in crossflow cooling towers or in crossflow usage generally and may be employed in counterflow cooling towers or other related flow applications.

Referring to <FIG>, the fill media or fill pack <NUM>" of the third preferred embodiment is for insertion into a cooling tower to cool a cooling medium, water, flowing through the fill pack <NUM>", wherein the third preferred fill pack <NUM>" is designed with the water flow direction <NUM>" being generally perpendicular to the airflow direction <NUM>". In contrast, the fill pack <NUM>' of the second preferred embodiment is also for insertion into a cooling tower and is designed with the water flow direction <NUM>' being generally parallel with and counter to the airflow direction <NUM>'. In the first and second preferred embodiments, the first fill sheet 10a, 10a' defines the first, second, third, fourth fifth and sixth flutes 12a, 12a', 12b, 12b', 12c, 12c', 12d, 12d', 12e, 12e', 12f, 12f' that extend generally parallel to the airflow direction <NUM>, <NUM>' along the arcuate, snaking path. In the third preferred embodiment, the first fill sheet 10a" defines first, second, third, fourth, fifth, sixth, seventh, eighth, ninth, tenth, eleventh and twelfth sheet flutes 12a", 12b", 12c", 12d", 12e", 12f', <NUM>", <NUM>", 12i", 12j", <NUM>", although the number of sheet flutes <NUM>, <NUM>', <NUM>" of the first, second and third preferred embodiments are not limiting and the fill sheets <NUM>, <NUM>', <NUM>" may include various numbers of sheet flutes <NUM>, <NUM>', <NUM>" depending on size, configuration, application, designer preferences and related factors. By continually changing the cross-sectional shape of the flute airflow portions <NUM>', <NUM>" along the sheet flutes <NUM>, <NUM>', <NUM>", air within the flute airflow portions <NUM>', <NUM>" is continually mixed, contributing to thermal performance.

The third preferred fill pack <NUM>" of <FIG>, <FIG> and <FIG> includes the first and second fill sheets 10a", 10b", but may also include additional fill sheets, such as the third, fourth, fifth, sixth, seventh, eighth and ninth fill sheets 10c", 10d", 10e", 10f", <NUM>", <NUM>", 10i", as shown in <FIG>, although the fill pack <NUM>" may include as few as the first and second fill sheets 10a", 10b" and less or more than the nine fill sheets 10c", 10d", 10e", 10f", <NUM>‴, <NUM>", 10i" of <FIG>. The first fill sheet 10a" defines the air intake edge <NUM>", the air exit edge <NUM>" and the airflow axis <NUM>" extending between the air intake edge <NUM>" and the air exit edge <NUM>". The first fill sheet 10a" defines a first flute section <NUM>" having a first inlet end 36a'", a first outlet end 36b" and a first peak 36c" extending between the first inlet end 36a" and the first outlet end 36b". In the third preferred embodiment, the first peak 36c" extends substantially parallel to the airflow axis <NUM>", but is not so limited. The first peak 36c" may extend at an angle or in a curved or arcuate manner relative to the airflow axis <NUM>".

The third preferred fill pack <NUM>" also includes the second fill sheet 10b" that defines a second flute section <NUM>" having a second inlet end 38a", a second outlet end 38b" and a second peak 38c" extending between the second inlet end 38a" and the second outlet end 38b". The first peak 36c" extends relative to the second peak 38c‴ such that the first flute airflow portion <NUM>" defined by the first and second flute sections <NUM>", <NUM>" has a cross-sectional shape that continuously changes between the first and second inlet ends 36a", 38a‴ and the first and second outlet ends 36b", 38b". In the third preferred embodiment, the second peak 38c" extends at an angle relative to the airflow direction <NUM>" and crosses the first peak 36c", as is shown in <FIG> in the first and second flute sections <NUM>", <NUM>". Continuously changing or modifying the cross-sectional shape of the first flute portion <NUM>" increases boundary mixing between the water flowing along the surface of the first and second fill sheets 10a", 10b" and the air flowing through the first flute airflow portion <NUM>". The change in cross-sectional shape improves mixing or surface exposure of the air as it flows through the first flute airflow portion <NUM>". In the third preferred embodiment, the first and second inlet ends 36a", 38a" and the first and second outlet ends 36b", 38b", respectively, are aligned along the airflow axis <NUM>" and define a first flute portion length Li". The first flute portion length L<NUM>" is approximately four to six inches (<NUM>-<NUM>") or ten to fifteen centimeters (<NUM>-<NUM>) in the third preferred embodiment, but is not so limited and may be greater or shorter, depending on designer and configuration purposes. The first and second peaks 36c", 38c" are not limited to extending generally linearly within the first and second flute sections <NUM>", <NUM>", as long as the extension of the first peak 36c" and the second peak 38c" result in continuous changing of the cross-sectional shape of the flute portion <NUM>" between the first and second fill sheets 10a'", 10b" in the first and second flute sections <NUM>", <NUM>‴ of the fill pack <NUM>".

In the third preferred embodiment, the second peak 38c" extends at a first flute portion angle Θ (<FIG>) relative to the first peak 36c" such that the shape of the cross-section of the first flute portion <NUM>" changes between the first and second inlet ends 36a", 38a" and the first and second outlet ends 36b", 38b". In the third preferred embodiment, the first flute portion angle Θ is approximately two to five degrees (<NUM>-<NUM>°), but is not so limited and may be larger or smaller or have a different configuration, such as curved, undulating or other shapes that facilitate cross-sectional modification of the first flute portion <NUM>". The cross-section preferably gradually and consistently changes between the first and second inlet ends 36a", 38a" and the first and second outlet ends 36b", 38b" of the first flute portion <NUM>", but is not so limited and may change in various manners, such as inconsistently and at various rates along the airflow direction <NUM>" to facilitate boundary mixing of the air with the water during operation, to improve heat transfer between the air and water in the fill pack <NUM>".

Referring to <FIG>, in the first and second preferred embodiments, the first peak 36c, 36c' of the first flute 12a, 12a' of the first sheet 10a, 10a', the second peak 38c' and the underlying peaks 38c' extend arcuately between the air intake edge <NUM>, <NUM>' and the air exit edge <NUM>, <NUM>'. The arcuate first and second peaks 36c, 36c', 38c' and the underlying peaks 38c' similarly result in a continuously changing cross-sectional shape along the length of the first flute portions <NUM>' between the air intake edge <NUM>, <NUM>' and the air exit edge <NUM>, <NUM>' of the preferred embodiments. The continuously changing cross-sectional shape in the flute portions <NUM>' facilitates an increase of boundary mixing and heat transfer between the water and air in the fill media or fill pack <NUM>' of the first and second preferred embodiments. The first preferred fill sheets <NUM> result in fill media with two back-to-back flute portions between the air intake and exit edges <NUM>, <NUM> separated by the spacer rows <NUM>. Specifically, each of the flutes <NUM> of the fill sheets <NUM> in the fill media of the first preferred embodiment define a flute portion <NUM> between an air intake spacer row 17a and an intermediate spacer row 17b and another flute portion <NUM> between the intermediate spacer row 17b and an air exit spacer row 17c. Similarly, the second preferred fill sheets <NUM>' result in the fill media <NUM>' with four back-to-back flute portions <NUM>' between the air intake and exit edges <NUM>', <NUM>' separated by the spacer rows <NUM>'. Specifically, each of the flutes <NUM>' of the fill sheets <NUM>' in the fill media <NUM>' of the second preferred embodiment define a flute portion <NUM>' between the air intake spacer row 17a' and a first intermediate spacer row 17b', a flute portion <NUM>' between the first intermediate spacer row 17b' and a second or central intermediate spacer row 17b', a flute portion <NUM>' between the second or central intermediate spacer row 17b' and a third intermediate spacer row 17b' and a flute portion between the third intermediate spacer row 17b' and the air exit spacer row 17c'. The fill media <NUM>' of the first and second preferred embodiments are not limited to including consecutive back-to-back flute portions <NUM>' between the air intake and exit edges <NUM>, <NUM>', <NUM>, <NUM>' and may include as few as a single flute portion <NUM>' located nearly anywhere on the fill media <NUM>', multiple flute portions <NUM>' that do not extend to and completely between the air intake and exit edges <NUM>, <NUM>', <NUM>, <NUM>' or the fill media <NUM>' that includes nearly full coverage of the fill media <NUM>' between the spacer rows <NUM>, <NUM>'.

Referring to <FIG>, the second peak 38c" of the second fill sheet 10b" of the third preferred embodiment is positioned at a first side of the first peak 36c" of the first fill sheet 10a" proximate the first and second inlet ends 36a", 38a" and the second peak 38c‴ is positioned at a second side of the first peak 36c" proximate the first and second outlet ends 36b'", 38b". The second peak 38c" accordingly, crosses the first peak 36c" as it extends from the second inlet end 38a" to the second outlet end 38b" of the first flute portion <NUM>" to facilitate the continuously changing cross-sectional shape of the first flute portion <NUM>".

Referring to <FIG>, in the third preferred embodiment, the first flute section <NUM>" of the first fill sheet 10a" and the second flute section <NUM>" of the second fill sheet 10b‴ define the first flute airflow portion <NUM>" that is positioned between the first and second fill sheets 10a", 10b" and an example first flute airflow portion <NUM>" is shown in <FIG>, <FIG> with cross-hatching. The first flute 12a" of the third preferred embodiment is also associated with a second flute airflow portion 42a", a third flute airflow portion 42b", a fourth flute airflow portion 42c", a fifth flute airflow portion 42d" and a sixth flute airflow portion 42e" that extend from the air intake edge <NUM>" to the air exit edge <NUM>". The plurality of flute portions <NUM>", 42a", 42b", 42c", 42d", 42e" preferably include alternating peak portions 36c", 38c" that are substantially parallel to the airflow axis <NUM>" and angled relative to the airflow axis <NUM>" at the first flute portion angle Θ such that the cross-section of the flute portion <NUM>‴ in the identified sections between the first and second fill sheets 10a", 10b" is constantly changing between the air intake edge <NUM>" and the air exit edge <NUM>". These flute portions <NUM>" are not limited to having the six flute portions <NUM>", 42a", 42b", 42c", 42d", 42e" with the constantly and consistently changing cross-sections and may have portions with cross-sections that are not changing or change in various inconsistent manners, based on designer preferences or for particular preferred functions.

Referring to <FIG>, <FIG> and <FIG>, the first flute section <NUM>" preferably also includes or is also bounded by a first valley 36d" at a first side of the first peak 36c‴ and a second valley 36e" at a second side of the first peak 36c" relative to the airflow direction <NUM>" and the airflow axis <NUM>". Similarly, the second flute section <NUM>" preferably also includes or is bounded by a third valley 38d" at a first side of the second peak 38c" and a fourth valley 38e" at a second side of the second peak 38c" relative to the airflow direction <NUM>" or the airflow axis <NUM>". In the third preferred embodiment, the first and second flute sections <NUM>", <NUM>" have a right-angle channel shape with the first and second peaks 36c", 38c" being curved or having a fillet. The first and second flute sections <NUM>", <NUM>" are not so limited and may have alternative shapes, such as the curving first and second flute sections <NUM>, <NUM>', <NUM>, <NUM>' of the first and second preferred embodiments that also arc or curve in a microstructure height direction of the first and second preferred first and second fill sheets 10a, 10a', 10b, 10b' or may be otherwise designed and configured to constantly change the cross-sectional shape of the plurality of flutes <NUM>, <NUM>' and the flute airflow portions <NUM>' as the air flows through the fill packs <NUM>' during operation to increase the boundary mixing of the air and the water in the fill media or fill packs <NUM>' during operation.

Referring to <FIG> and <FIG>, the second and third preferred fill media or fill packs <NUM>', <NUM>‴ and the fill sheets <NUM>', <NUM>" have an airflow length LA', LA" defined between the air intake edge <NUM>', <NUM>" and the air exit edge <NUM>', <NUM>". In the preferred embodiments, the airflow length LA', LA" is approximately twenty-four to fifty-six inches (<NUM>-<NUM>") or sixty-one to one hundred forty centimeters (<NUM>-<NUM>), but is not so limited. The airflow length LA', LA" may be greater or smaller depending on cooling tower requirements, designer preferences, performance requirements or additional design factors. In addition, the fill media or fill packs <NUM>', <NUM>" may be stacked on or adjacent to each other such that a first fill pack <NUM>', <NUM>" is positioned with its air exit edge <NUM>', <NUM>" adjacent the air intake edge <NUM>', <NUM>" of a second fill pack <NUM>', <NUM>" so that air flows through both of the packs <NUM>', <NUM>" in the airflow direction <NUM>, <NUM>', <NUM>" and water flows through the packs <NUM>', <NUM>" in the water flow direction <NUM>, <NUM>', <NUM>".

Referring to <FIG>, in operation, the first and second preferred fill packs <NUM>' are preferably inserted into a counterflow cooling tower such that air flows from the air intake edge <NUM>, <NUM>' along the plurality of flutes <NUM>, <NUM>' to the air exit edge <NUM>, <NUM>' and water or other cooling fluid flows under the force of gravity in the water flow direction <NUM>, <NUM>' from the air exit edge <NUM>, <NUM>' to the air intake edge <NUM>, <NUM>'. The curved or arcuate shape of the plurality of flutes <NUM>, <NUM>' and the flute airflow portions <NUM>' between the fill sheets <NUM>, <NUM>' results in the air flowing through the plurality of flute airflow portions <NUM>' changing direction and mixing along the interface with the water film on the surfaces of the plurality of fill sheets <NUM>, <NUM>' in the fill media or fill packs <NUM>'. The mixing of the air flowing through the plurality of flute airflow portions <NUM>' prevents water saturated air from remaining in contact with the water film, such that dryer air is exposed to the water film, as opposed to remaining centrally located within the plurality of flute airflow portions <NUM>' without coming into direct contact with the water film, as may occur in prior art constant cross-section flutes (not shown) that do not constantly change from end to end. The air flowing through the plurality of flute airflow portions <NUM>' has a typical flow velocity range of approximately three hundred to eight hundred feet per minute (<NUM>-<NUM> ft/min) or one hundred fifty to four hundred centimeters per second (<NUM>-<NUM>/sec) average velocity of approximately seven hundred feet per minute (<NUM> ft/min) or one hundred forty inches per second (<NUM> in/sec) or three hundred fifty-six centimeters per second (<NUM>/sec) such that any given portion of the air is within the fill pack <NUM>' for only a portion of a second. Relatively quick exposure of all portions of the airstream to the water film on the surfaces of the fill sheets <NUM>, <NUM>' and in a relatively quick manner is preferred to maximize heat transfer between the air and the water or cooling medium that is flowing through the fill pack <NUM>'. The changing cross-sectional shape of the plurality of flute airflow portions <NUM>' of the first and second preferred embodiments facilitates mixing of the air flowing through the plurality of flute airflow portions <NUM>' to maximize relatively quick exposure of all of the air to the surface of the water film.

Referring to <FIG>, in operation, the third preferred fill pack <NUM>" is preferably inserted into a crossflow cooling tower such that air flows from the air intake edge <NUM>" along the plurality of flute airflow portions <NUM>" to the air exit edge <NUM>" in the airflow direction <NUM>" and water flows under the force of gravity in the water flow direction <NUM>" from the top edge <NUM> to the bottom edge <NUM>. The third preferred fill packs <NUM>" are not limited to use in use in crossflow cooling towers or in crossflow usage generally and may be employed in counterflow cooling towers or other related flow applications. The shifting of the peaks 36c", 38c" of the flute sections <NUM>", <NUM>", which results in the constantly changing cross-sections of the flute airflow portions <NUM>" results in the air flowing through the fill media or fill packs <NUM>" changing direction and mixing along the interface with the water film on the surfaces of the plurality of flute airflow portions <NUM>". The mixing of the air flowing through the plurality of flutes <NUM>" and the flute airflow portions <NUM>" prevents water saturated air from remaining in contact with the water film, such that dryer air is exposed to the water film, as opposed to the dryer air remaining centrally located within the flute airflow portions <NUM>" without coming into direct contact with the water film, as may occur in prior art constant cross-section flutes (not shown).

In the third preferred embodiment, the peaks 36c", 38c" are alternatively oriented at the first flute portion angle Θ such that they are directed downwardly toward the air intake edge <NUM>". This downward directing of the peaks 36c", 38c" urges the water or other cooling medium toward the air intake edge <NUM>" against the force of the airflow that is urging the flowing water or cooling medium toward the air exit edge <NUM>". The orientation of the peaks 36c", 38c" also, therefore, resists pooling or damming of the water or cooling medium at the air exit edge <NUM>", which may occur without the described orientation of the peaks 36c", 38c" or other water or cooling medium anti-pooling features.

Referring to <FIG>, the fourth, eighth, and twelfth flutes 12d", <NUM>", <NUM>" of the third preferred fill sheets <NUM>" are comprised of indexing flutes 12d", <NUM>", <NUM>" that do not include the peaks 36c", 38c" that change orientation relative to each other to change the cross-sectional shapes of the indexing flutes 12d", <NUM>", <NUM>". The indexing flutes 12d", <NUM>", <NUM>" are utilized to index the fill sheets <NUM>", which are manufactured in a continuous thermoforming process, such that the first and second fill sheets 10a", 10b" and the additional fill sheets 10c", 10d", 10e", 10f', <NUM>", <NUM>", <NUM>" are appropriately aligned when assembled into the fill media or fill pack <NUM>" so that the plurality of flutes <NUM>" have the consistently and continuously changing cross-sectional shapes between the air intake edge <NUM>" and the air exit edge <NUM>". Specifically, the fill sheets <NUM>" are preferably assembled by rotating the fill sheets <NUM>" one hundred eighty degrees (<NUM>°) relative to each successive fill sheet <NUM>" in the stacking of the fill packs <NUM>" to arrange the alternatively oriented peaks 36c", 38c" of the adjacent fill sheets <NUM>" in the preferred fill packs <NUM>". The fill sheets <NUM>" are not limited to including the indexing flutes 12d", <NUM>", <NUM>", but the indexing flutes 12d", <NUM>", <NUM>" are preferred for the reasons described herein. Alternatively, the fill sheets <NUM>" could be designed with different configurations for every other fill sheet <NUM>" that is added to the fill pack <NUM>" assembly to facilitate the alternatively oriented peaks 36c", 38c" of the third preferred embodiment and without the indexing flutes 12d", <NUM>", <NUM>". In this alternative configuration, the fill sheets are not rotated, but the different fill sheets are stacked alternatively to define the fill media.

Referring to <FIG>, the fill sheets <NUM>" of the third preferred embodiment are shown with relatively flat or planar surfaces defining the plurality of flutes <NUM>", but are not so limited. The fill sheets <NUM>" may include the microstructure, such as the microstructure <NUM>, <NUM>' of the first or second preferred embodiments, or other surface features that increase the surface area of the fill sheets <NUM>, <NUM>', <NUM>" for additional exposure of the film of water or other cooling medium to the airflow. In addition, the fill sheets <NUM>, <NUM>', <NUM>" may incorporate edge features, such as louvers, drift eliminators and other features, which are not shown for clarity purposes, but may be attached to or in certain embodiments integrated into the fill sheets <NUM>, <NUM>', <NUM>" and fill media or fill packs <NUM>', <NUM>". The fill sheets <NUM>, <NUM>', <NUM>" are also preferably designed for limited pressure drop for the airflow, while maximizing the heat transfer between the air flowing through the fill media or fill pack <NUM>', <NUM>" and the water or cooling medium flowing through the fill media or fill pack <NUM>', <NUM>". In the third preferred embodiment, the fill sheets <NUM>" in the fill pack <NUM>" are spaced from each other at a spacing distance S of approximately nineteen millimeters (<NUM>) or approximately three-quarters of an inch (¾"), but are not so limited and may have greater or smaller spacing distances S for various applications, functions and designer preferences.

Referring to <FIG>, the third preferred fill pack <NUM>" is shown as a two fill sheet <NUM>" assembly, including the first fill sheet 10a" and the second fill sheet 10b", where the second fill sheet 10b" is shown extending past the first fill sheet 10a" a short distance to illustrate the orientation of the first and second peaks 36c", 38c" relative to each other. The third preferred fill pack <NUM>" is preferably not designed with the second fill sheet 10b" extending beyond the first fill sheet 10a" at the air exit edge <NUM>" as the adjacent fill sheets <NUM>" preferably terminate immediately adjacent or proximate to each other in the preferred fill pack <NUM>".

Referring to <FIG>, the second preferred fill pack <NUM>' is configured as a counterflow fill pack <NUM>' with the air flowing in the airflow direction <NUM>', generally parallel to the airflow axis <NUM>', from the air intake edge <NUM>' to the air exit edge <NUM>' and the water flowing under the force of gravity from the air exit edge <NUM>' to the air intake edge <NUM>' in the water flow direction <NUM>'. The fill sheets <NUM>' of the second preferred fill pack <NUM>' may include the connections <NUM>', which are preferably comprised of spacer or plateau connections <NUM> having a generally planar plateaus <NUM>' from which the connectors <NUM> may extend. The connectors <NUM>' may be bonded, secured to glued together or positioned adjacent to each other to define the fill pack <NUM>'. The fill sheets <NUM>' of the second preferred embodiment include the arcuate, wavy or sinusoidal-shaped sheet flutes <NUM>' that extend between the air intake and exit edges <NUM>', <NUM>' to guide the air through the fill pack <NUM>'.

Referring to <FIG>, the representative cross-sections of the fill pack <NUM>' in the three identified areas of the first and second flute portions <NUM>', <NUM>' or along the flute airflow portion <NUM>' shows the change in at least portions of the flute airflow portion <NUM>' between the first and second fill sheets 10a', 10b' that facilitates mixing between the flowing air and water near the surfaces of the first and second fill sheets 10a', 10b' within the flute airflow portion <NUM>". The second peak 38c' of the second flute section <NUM>' moves laterally relative to the first peak 36c' of the first flute section <NUM>' thereby constantly modifying the cross-sectional shape and air flow properties of the flute airflow portion <NUM>' as the air flows in the airflow direction <NUM>' between the first and second inlet ends 36a', 38a' and the first and second outlet ends 36b', 38b'. The adjacent flute airflow portions <NUM>' in the fill pack <NUM>' similarly have changing cross-sectional shapes that promote flow of the air between the adjacent flute airflow portions <NUM>' over and under the peaks 36c', 38c' and the valleys 36d', 36e', 38d', 38e' of the flute sections <NUM>', <NUM>'. Although the changing cross-sectional shape of the flute airflow portions <NUM>' in the first and second flute sections <NUM>', <NUM>' is shown in <FIG>, it is preferred that each of the flute airflow sections <NUM>' of the first, second, third, fourth, fifth and sixth sheet flutes 12a', 12b', 12c', 12d', 12e', 12f of each of the fill sheets <NUM>' in the second preferred fill pack <NUM>' have similarly shifting cross-sections and configurations.

Referring to <FIG>, in the first and second preferred embodiments, the fill sheets <NUM>, <NUM>' include the flute section <NUM>, <NUM>' that extends between the first inlet end 36a, 36a' and the first outlet end 36b, 36b' and, when assembled into the fill media <NUM>', define the first flute airflow portion <NUM>'. The fill media <NUM>' includes a plurality of flute sections <NUM>, <NUM>' and flute airflow portions <NUM>' defined by the sheet flutes <NUM>, <NUM>' of adjacent fill sheets <NUM>, <NUM>'. The first flute section <NUM>, <NUM>' defines a first flute section length LF, LF', preferably between adjacent spacer rows <NUM>, <NUM>'. In the first and second preferred embodiments, the first flute section length LF, LF' is approximately four to eight inches (<NUM>-<NUM>"), although the first flute section <NUM>, <NUM>' is not so limited and may be longer, such as eight to twelve inches (<NUM>-<NUM>") or shorter, such as one to four inches (<NUM>-<NUM>"), depending on the design and function of the fill sheets <NUM>, <NUM>'. The flute sections <NUM>, <NUM>' are defined between the spacer rows <NUM>, <NUM>' in the first and second preferred embodiments, such as between the air intake spacer row 17a, 17a' and the intermediate spacer row 17c, 17c', between the air exit spacer row 17b, 17b' and the intermediate spacer row 17c, 17c' or between two adjacent intermediate spacer rows 17c'. In the first and second preferred embodiments, the flute sections <NUM>, <NUM>' are arcuate and extend to opposite sides of the airflow axis <NUM>, <NUM>' in each successive flute section <NUM>, <NUM>' on opposite sides of the spacer rows <NUM>, <NUM>'. For example, in the first preferred embodiment, the flute sections <NUM> in the lower portion 11b extend to a first side of the airflow axis <NUM> and the flute sections <NUM> in the upper portion 11a arc or extend to a second, opposite side of the airflow axis <NUM>. In the second preferred embodiment, the flute sections <NUM>' in the upper and lower portions 11a', 11b' are similarly configured to the fill first preferred fill sheet <NUM>, but the second preferred fill sheet <NUM>' includes the central intermediate spacer row 17c', wherein adjacent or successive flute sections <NUM>' extend to the same side of the airflow axis <NUM>' at opposite sides of the central intermediate spacer row 17c'. Referring to <FIG>, the first flute section <NUM>" also defined the first flute section length LF".

Referring to <FIG>, in the first and second preferred embodiments, the sheet flutes <NUM>, <NUM>' of the flute sections <NUM>, <NUM>' have the flute peaks 36c, 36c'. The flute peaks 36c, 36c' of the first and second preferred embodiments are arcuate and define a flute vector <NUM>, <NUM>' that is comprised of a line extending at a tangent to the flute peaks 36c, 36c'. The flute vector <NUM>, <NUM>' in the first and second preferred embodiments changes constantly between the inlet and outlet ends 36a, 36a', 36b, 36b' of the flute sections <NUM>, <NUM>' or flute airflow portions <NUM>'. The flute vectors <NUM>, <NUM>' are independent of the microstructure angle Δ, Δ' in that the microstructure angle Δ, Δ' is not perpendicular to the extension direction of the sheet flutes <NUM>, <NUM>' or the flute vectors <NUM>, <NUM>'. In prior art fill sheets, microstructure is typically positioned perpendicular to the flute vectors of the flutes of the sheets. In addition, the microstructure angle Δ, Δ' does not extend parallel to the flute vectors <NUM>, <NUM>', such that there is consistently an arcuate angle defined between the microstructure angle Δ, Δ' and the flute vectors <NUM>, <NUM>' in the preferred embodiments. In addition, in the first and second preferred embodiments, the first flute vectors <NUM>, <NUM>' are constantly changing between the inlet and outlet ends 36a, 36a', 36b, 36b' such that the acute angle between the microstructure angle Δ, Δ' and the flute vectors <NUM>, <NUM>' is constantly changing between the inlet and outlet ends 36a, 36a', 36b, 36b' along the flute sections <NUM>, <NUM>'. Referring to <FIG>, in the third preferred embodiment, the sheet flutes <NUM>" of the flute sections <NUM>" have the flute vectors <NUM>" that extend along or parallel to the flute peaks 36c". The flute vectors <NUM>", therefore, alternatively extend generally parallel to the airflow axis <NUM>" and at the flute portion angle Θ" relative to the airflow axis <NUM>". Although the third preferred embodiment of the fill sheets <NUM>" does not show microstructure thereon, the microstructure angle of microstructure that is positioned on the fill sheets <NUM>" would be oriented independently of the flute vectors <NUM>" similarly to the first and second preferred embodiments. The third preferred embodiment of the fill sheets <NUM>" could, for example, include substantially the same microstructure <NUM>, <NUM>' as the first and second preferred embodiments having the Chevron or herringbone configuration with an inflection line at the lines positioned generally centrally between the spacer rows <NUM>" and extending generally parallel to the lateral axis <NUM>".

Claim 1:
A fill sheet (<NUM>) for insertion into a counterflow cooling tower, wherein the fill sheet is (<NUM>) oriented such that air flows along a plurality of flutes from an intake edge (<NUM>) toward an air exit edge (<NUM>) and water flows from the air exit edge (<NUM>) toward the air intake edge (<NUM>), to cool the water flowing over the sheet, the fill sheet comprising:
the air intake edge (<NUM>);
the air exit edge (<NUM>) positioned opposite the air intake edge (<NUM>);
the plurality of flutes extending from the air intake edge (<NUM>) toward the air exit edge (<NUM>), an airflow axis (<NUM>) extending through the air intake edge (<NUM>) and the air exit edge (<NUM>) and a lateral axis (<NUM>) extending substantially perpendicular to the airflow axis (<NUM>), the plurality of flutes including a first flute section (<NUM>) having a first peak (36c), a first inlet end (36a), a first outlet end (36b) and defining a first flute vector (<NUM>), the first flute vector (<NUM>) being tangent relative to the first peak(36c), and
microstructure (<NUM>) formed on the plurality of flutes, the microstructure (<NUM>) defining a microstructure angle (Δ) of fifteen to forty-five degrees relative to the lateral axis (<NUM>), the microstructure (<NUM>) serves to redistribute the water both within and between the plurality of flutes by generating water flow in a direction of micro-corrugations of the microstructure (<NUM>), the microstructure angle (Δ) being independent of the first flute vector (<NUM>), characterized in that the first flute vector (<NUM>) constantly changes between the first inlet end (36a) and the first outlet end (36b).