AU2009283776A1 - Direct evaporative heat exchangers, methods of manufacture thereof and applications thereof to multi-stage cooling systems - Google Patents

Abstract

Direct evaporative Heat Exchanger, methods of manufacture thereof and applications thereof to multistage cooling systems are disclosed. The Direct Evaporative Heat Exchanger of this invention includes a number of polymer substrates where a top surface and a bottom surface of each of the polymer substrate are treated to render each surface hydrophilic which renders high thermal efficiency and enhanced dimensional stability. The Multi Stage Evaporative Cooling Systems comprise an indirect evaporation component where the fluid is pre-cooled indirectly with the heat exchangers, followed by the direct evaporative heat exchanger where the pre-cooled fluid is further cooled directly by evaporative cooling. The Direct evaporative heat exchanger of this invention can be utilized alone or in combination in a multistage cooling apparatus also including additional cooling components such as cooling coils or heat pipes. This Invention also relates to other Multi-Stage cooling devices.

Description

WO 2010/020997 PCT/IN2009/000207 1 DIRECT EVAPORATIVE HEAT EXCHANGER, METHODS . OF MANUFACTURE THEREOF AND APPLICATIONS THEREOF TO MULTI STAGE COOLING SYSTEMS FIELD OF INVENTION This invention relates to direct adiabatic evaporative cooling technology,, and particularly to direct adiabatic evaporative cooling devices, also referred to as Direct Evaporative Heat Exchangers, used for conditioning fluids such as air and systems that utilize such devices. This Invention also relates to other Multi-Stage cooling devices. BACKGROUND AND PRIOR ART Adiabatic evaporative heat exchangers (including contact bodies of packaging for gas and liquid contact) have been proposed and are conventionally used. In a typical adiabatic evaporative heat exchanger corrugated sheets are placed adjacent to one another with their ridges or crests contacting each other so that channels or passageways are formed between the sheets to provide continuously varying passages in the sheets. The commercially available adiabatic evaporative heat exchangers, also referred to as cooling pads or cooling mediums, (such as, for example, the CeldekTM 5090 15) consist of specially impregnated and corrugated cellulose paper sheets or cellulosic materials with different flute angles. During operation, water would be sprayed from the top using a distributor pad / a spraying system.. Water would flow down the corrugated surfaces (also referred to as flutes) of the cooling pad. The water would flow, through the flutes, wetting the surfaces, and thusthe entire cooling pad/medium. In a typical application water would flow down by gravity through the flutes thus wetting the surface. The second fluid, typically air, passes across the heat exchanger or cooling pads. The passage of air is through the same flutes that have got wetted by water as mentioned earlier. Some of the water is evaporated by the warm and dry air that passes through the flutes, across the cooling pad. The heat that is needed for evaporation is taken from the air itself. Thus the air is cooled as it travels across the cooling pad (heat exchanger). Other cooling pad configurations have been proposed. A conventional method of cooling warm or hot water with air utilizes an oblique honeycomb made of conventional polyvinyl chloride, in one example, in a cooling tower. However, since the oblique honeycomb is made of conventional polyvinyl chloride, warm water or the like is repelled from the surface of the oblique honeycomb and falls in the shape of water drops. Specifically, since the surface of the oblique honeycomb is not uniformly wetted by warm water or the like, the large surface area of the oblique honeycomb cannot be fully utilized. Therefore, it is 'difficult to use the oblique honeycomb made of conventional polyvinyl chloride as an air cooling device/cooling pad providing high thermal efficiency.

WO 2010/020997 PCT/IN2009/000207 2 DESCRIPTION OF RELATED ART Adiabatic evaporative heat exchangers utilizing corrugated cellulose paper sheets or cellulosic material are commercially available and were originally disclosed in several patents. -One such heat exchanger (contact body) is shown in U.S. Pat. No. 3,262,682. An improvement of the basic contact body shown in Bredberg, U.S. Pat. No. 3,262,682, was developed and disclosed in U.S. Pat. No. 3,792,841 to Munters. .A variety of other improvements have been proposed, typical of which is U.S. Pat. No. 5,143,658. Yet, commercially available adiabatic evaporative cooling media- (cooling pads) still utilize corrugated cellulose paper sheets (or cellulosic material) or cellulose paper with glass fibre impregnations., During use of the cellulose cooling pad, the entire thickness of the pad absorbs water and can become softer and looses rigidity and needs to be supported externally. Furthermore, the cellulose paper sheet thickness can increase. upon absorption of water. The cooling pads utilizing plastic, as proposed in U.S.-Pat. No. 3,792,841, suffer from reduced efficiency as described above. There is a need for high- thermal efficiency adiabatic -heat exchangers .(cooling pads) that have both dimensional stability, enabling modular construction of heat exchangers and of systems, and also have the desired thermal efficiency STATEMENT OF THE INVENTION In one embodiment, the heat exchanger of this invention includes a number of polymer substrates where a top surface and a bottom surface of each of the polymer substrate are treated to render each surface hydrophilic. Each polymer substrate is corrugated resulting in a number of corrugated polymer sheets. Each one of ,the corrugated polymer sheets is 'disposed, in a substantially parallel manner, on an adjacent corrugated polymer sheet; the corrugations* in one corrugated polymer sheet being disposed at a predetermined angle with respect to corrugations on the adjacent corrugated polymer sheet. Another embodiment of this invention provides an indirect direct evaporative' cooling apparatus (IDEC) also referred to as Two Stage Evaporative cooling apparatus including an indirect evaporative heat exchanger (cooling component) and a direct adiabatic evaporative cooling component (heat exchanger) of this invention -as disclosed hereinabove. The indirect heat exchanger can be a conventional indirect evaporative heat exchanger or can be a non-conventional 'indirect evaporative heat exchanger including one or more modules, where each module includes a number of units where. each unit has two polymer substrates, one surface of each substrate having been rendered substantially hydrophilic and other surface of each substrate being substantially hydrophobic. In the non conventional indirect heat exchanger, two substrates are adjacent to one another and have a number of channels disposed between them; the channels being attached to the hydrophobic surface of each of the substrates. At each WO 2010/020997 PCT/IN2009/000207 3 substantially hydrophilic surface, a substantially compliant nonwoven material is disposed on and substantially fixedly attached to the surface at 'a number of locations. Embodiments of the direct heat: exchanger of this invention in which the polymer substrate is rendered hydrophilic can exhibit longer use life, higher cooling capacity/efficiency and enhanced dimensional stability. The core of the polymer substrate (the core being the polymer substrate with the exclusion of the hydrophilic layers), during operation, remains dry and only the hydrophilic surfaces (layers) is wetted by an evaporative liquid. Therefore the heat exchanger does not suffer from a loss of dimensional stability or rigidity, due to being wetted by the evaporative liquid. The stiffness of the polymer substrate allows the design of large cooling pads or the scaling up/modular design of the heat exchanger. In one embodiment, the method/process for manufacturing the adiabatic evaporative heat exchanger of these teachings includes: a) rendering both surfaces of each one of two or more polymer substrates hydrophilic, b) corrugating each one of the polymer substrates; c) disposing each corrugated polymer substrate on another one of the corrugated polymer substrates where the corrugations on one corrugated polymer substrate are disposed at a predetermined angle with respect to corrugations on an adjacent corrugated polymer substrate, and d) fixedly securing each corrugated polymer substrate to an adjacent corrugated polymer substrate. Other detailed embodiments of the system and the method of this invention are disclosed herein below. OBJECTS OF THE INVENTION The present invention meets the needs identified in the above description of related art as well as meeting other needs. It is an object of this invention to provide a high thermal efficiency adiabatic evaporative heat exchanger that also has enhanced dimensional stability and enables cost-effectiveness. It is also an object of this invention to provide an adiabatic.. evaporative heat exchanger capable of being used in a modular manner to make or create a small or large cooling system. It is a further object of this invention to provide an adiabatic evaporative heat exchanger that can be utilized in modular designs of an indirect direct evaporative cooling apparatus. Another object of this invention is to WO 2010/020997 PCT/IN2009/000207 4 provide adiabatic heat exchangers that can be utilized in Multistage cooling apparatus., It is yet another object of this invention to provide methods for manufacturing a high thermal efficiency adiabatic evaporative heat exchanger that also has enhanced dimensional stability. BRIEF DESCRIPTION OF THE DRAWINGS For a better 'understanding of the present invention reference is made to the accompanying drawings and detailed description. Figures 1 a and lb are schematic graphical representations of a substrate as used in an embodiment of.this invention; Figures 2a and 2b are schematic graphical representations of a substrate after processing according to one embodiment of the method of this invention; Figures 3a and 3b are schematic graphical representations of a substrate after further processing according to one embodiment of the method of this invention; Figure 4a, 4b, 4c and 4 d are schematic graphical representations of one embodiment.of a corrugated substrate as utilized in this invention; Figure 5a and 5b are schematic graphical representations of one embodiment of a variation of corrugated substrate as utilized in this invention; Figure 6a & 6b are schematic graphical representations of an embodiment of the heat exchanger of this invention; Figure 7 is a conventional psychometric chart showing the thermodynamic process utilized, in this invention; Figure 8 is a conventional Psychometric chart showing the thermodynamic processes of primary and secondary air streams in a sensible heat exchanger; Figure 9 is a vertical cross sectional schematic view of an embodiment of the IDEC / two-stage.evaporative: cooling apparatus s of this invention showing main parts of the embodiment; Figure 10 is -a horizontal cross sectional schematic view of the embodiment shown in Figure 9 showing water distribution, air flow pattern and other parts of the embodiment; Figure I1 is a Schematic representation of water distribution system of the embodiment shown in Figure 9; WO 2010/020997 PCT/IN2009/000207 5 Figure 12 is a Schematic representation of Exhaust air system of living space for application of an embodiment of the two-stage evaporative cooling -Indirect Direct Evaporative Cooling apparatus of this invention; Figures 13 a, 13b, 13c and 13d are Isometric views of an embodiment of the non-conventional indirect evaporative heat exchanger of this invention, which depicts a Cross flow type of heat exchanger; Figure 14a and 14b are views of an embodiment of a unit of an embodiment of the indirect evaporative heat exchanger of this invention; Figure 15a, 15b and 15c are-a front view (15a), side view (15b) and close up isometric view (15 c), of a portion of a component of an embodiment of the non conventional indirect evaporative heat exchanger of this invention Figures 16a through 16e is an isometric view- of embodiments of a module and a cartridge in an embodiment of the non-conventional indirect evaporative heat exchanger of this invention; Figures 16a-16e correspond to a Cross flow heat exchanger; Figure 17a,17b,17c and 17d are cross-sectional views of several embodiments of. channels in an embodiment of the non-conventional. indirect evaporative heat exchanger of this invention; and Figure 18 is a schematic block diagram representation of a component of an embodiment of the two-stage evaporative cooling apparatus of this invention.

WO 2010/020997 PCT/IN2009/000207 6 List of Parts Item Description 1 Structural Casing/Metallic Casing 2 Filters -3 Blower 4 Blower Motor 5 -.ulleys 6 Befts\ 7 Heat Exchanger 1-DAMA 8 Heat Exchanger l1 9 DAMA Heat exchanger Housing 10 Convas Duct 1. 11 Plenum I 12 Plenum 1I 13 Canvas Duct 11 14 Water Tank 15 SecAir Hood 16 Pump1 17 Pump2 18 PVC Piping I Water Catridge 1 20 PVC Piping 1. Water Catridge 2 22 U.V treatment 23 Primary inlet air 24 Sensibally cooled Primary air 25 Treated outlet air 26 Secondary Inlet- air 27 Secondary outlet air 28 Exhaust air system 29 Living space 30 Micro controller/Processor 31 PP Substrate 32 Spun Bonded Nonwoven PP Fabric 33 PP Strip 34 Water distribution Catridge(19) -Close view 35 Mister 36 Water Spray 37 Water Film 38 Channels 39 CIannels 40 One unit 41 One unit 42 Alternate channels 70 Interconnection componet/Bus 75 Sensors 80 ,,Media WO 2010/020997 PCT/IN2009/000207 7 100 Polymer Substrate 150 Surface. 170 Surface 190 Treated Surface 220/240 Apices 260 Dimple/Ridge/Indentations 270 Distributor Pad DETAILED DESCRIPTION OF THE EMBODIMENTS Embodiments of systems (heat exchangers) for direct adiabatic cooling, methods for the manufacturing thereof and cooling apparatus utilizing embodiments of the heat exchangei- of this invention are disclosed herein below. "Compliant" and "compliance," as used herein, refer to the terms as used in the mechanical arts. In one embodiment, the adiabatic direct heat exchanger of this invention comprises a number of polymer substrates (100, Figure Ia). During manufacturing, each' of the surfaces 150, 170 of each polymer substrate is rendered substantially hydrophilic by. an appropriate treatment of the substrate (190, Figure 2a). (Before being treated, the surfaces of the polymer substrate 100 are substantially hydrophobic.) In one embodinient, each treated polymer substrate undergoes the next process to create dimples or ridges or indentations on the treated surface (260, Figure 3a, 3b). Such treated polymer substrate is corrugated. (A treated corrugated polymer substrate is hereafter referred to as a corrugated polymer sheet. -. Corrugated polymer sheets of different radii of corrugations are shown in Figures 4a through 4d. It should be noted .that the invention is not limited to only the diameter shown. It should also be noted that the corrugation may have curvature with varying widths and:heights as shown as 'w' and 'h' respectively in Figures 5a and 5b. It should be noted that the invention is not limited to only the dimensions shown.) Each such corrugated polymer sheet is disposed on an adjacent corrugated polymer .sheet in a substantially parallel manner. Corrugations on one corrugated polymer sheet are disposed at a predetermined angle with respect to corrugations on an adjacent corrugated polymer sheet. Each corrugated polymer sheet is fixedly secured to an adjacent corrugated polymer sheet. In one instance, the two corrugated polymer sheets are fixedly secure at the apices (220, 240, Figure 4a through 4d as well as 5a and 5b) of the corrugations. The resulting heat exchanger, where the corrugations on one corrugated polymer sheet are disposed at an angle with respect to an adjacent corrugated polymer sheet, is shown in Figure 6a. (In Fig. 6, the angle is 900, but this invention is not limited to this angle.). Figure 6 b gives another isometric view of the heat exchanger, as used in the application. It should be noted that the three dimensions of the heat exchanger length x breadth-x depth are also herein referred to as height x width x depth or thickness.

WO 2010/020997 PCT/IN2009/000207 8 In another embodiment, during fabrication (manufacturing) a number of indentations (260, Figure 3a and 3b) are formed on at least one of the surfaces 150, 170 of the polymer substrate 100. In one instance, the indentations are formed after the surface 150 or 170 is rendered hydrophilic. The indentations are formed before the polymer substrate is corrugated. In one instance, the-number of indentations is formed by means of a roller with a number of protrusions. The roller is placed over the surface on which the indentations are going to be formed and rolled over that surface. Each of the surfaces 150, 170 can be rendered hydrophilic by a variety of methods. In one instance, the surface is plasma treated thereby creating polymer radicals on the surface of the polymer substrate 100. A hydrophilic monomer is engrafted onto the polymer substrate by means of the polymer radicals. (See for example US Patent 5,028,332, which is incorporated by reference herein in its .entirety). In other instances, a hydrophilic polymer is grafted onto a hydrophobic polymer substrate surface pretreated by oxygen plasma and silanized (see for example, Dapeng Wu et al., Lab Chip, 2006, 6, 942 - 947, DOI: 10.1039/b600765a). It should be noted that this invention is not limited to only the present exemplary instances of hydrophilization. (A variety of exemplary instances of plasma treatment and hydrophilization are within the scope of the art. See, for example, HI. Kim et al., Journal of membrane science, 286, pp. 193-201, 2006, which is incorporated by reference in its entirety herein.) UV radiation has also been used to pre-treat the surface of the Polymer substrate. In some instances, the surface is dried after being pretreated. In yet another instance, the surface of the polymer substrate is coated with a hydrophilic polymer in solution with'a solvent and the solvent is then evaporated (see for example, US Patent 4,589,873, which is incorporated by reference herein in its entirety). In a further instance, the polymer surface of the substrate- is coated with a solvent solution; another solvent solution including a hydrophilic copolymer is subsequently applied to the surface, the hydrophilic copolymer reacting with a component in the first solution. The solvents are then evaporated leaving the surface hydrophilic (see for example US Patent 4,373,009, which is hereby incorporated by reference in its entirety). In still a further instance, the polymer substrate is coated or submerged in an alkali solution and the substrate is subsequently dried; the substrate is coated or submerged in another solution having compounds -that cross-link upon contact with alkali. The polymer substrate is washed to remove alkali and unreacted components, leaving the substrate hydrophilic (see for example US Patent 4,851,121, which is hereby incorporated by reference in its entirety). In another exemplary instance, an ionic polymer layer is obtained on the- hydrophobic surface by a treatment such as plasma discharge, utilizing a glow discharge plasma, electron beam treatment corona discharge, x-ray treatment or acid/base chemical modification and a polyelectrolyte is coated and ionically bonded to the polymeric layer (see, for WO 2010/020997 PCT/IN2009/000207 9 example, US Patent 5,700,559, which is incorporated by reference herein in its entirety). In still other instances, the surface 'is coated and the .coating fluid, in some instances, typically contains some surfactants to reduce the surface tension of the. coating fluid and to allow wetting (by Water or other' fluids) of the treated hydrophobic surface. In one exemplary instance, an initiator is coated onto the surface and a hydrophilic polymer is grafted onto the initiator (see for example, T. Carroll et al., Journal of Membrane Science, 203, pp. 3-13, 2002, which' is incorporated by reference herein in its entirety). Other instances, of coating a polymer that renders the surface hydrophilic are disclosed in US patents 4,794,002 and 5,976,995, both of which are incorporated by reference herein in their entirety. In yet another exemplary instance, a hydrophobic polymer surface is coated with a thin film of a biodegradable material, such as, but not limited to, starch, where the adhesion of the biodegradable material toI the. hydrophobic surface can be improved by draft polymerizing the biodegradable material with a synthetic monomer. (See, for example US Patent 7,052,776, which is incorporated by reference herein in-its entirety). In yet another exemplary instance a hydrophilic polymer is coated on the surface of the hydrophobic substrate and cross-linked to a hydrogel (see for example US patent 6,648,836, which is incorporated by reference herein in its entirety, where the hydrophilic polymer is. bound to the substrate by any suitable method, for example for example, but not limited to, gamma or electron beam radiation). In a further.exemplary instance, the hydrophobic substrate is also treated (such as, but not limited to, by Ozone treatment) in order to functionalize the surface and block copolymers are grafted onto the functionalized surface in order to obtain a hydrophilic layer with antibacterial properties (see, for example, F. Yao et., Antibacterial effect of surface-functionalized polypropylene hollowfiber membrane from surface initiated atom transfer radical polymerization, Journal of Membrane Science (2008), doi:10.1016/j.mremsci.2008.03.049, which is incorporated by reference herein in its entirety). The composition of the coated material will typically be dual in nature - it will have some hydrophobic material that will have an affinity for the hydrophobic substrate and the hydrophilic component that will hold water. The coating process can be a single step or two steps. In one instance, in the one, step case, the coating can consist of a block copolymer of a hydrophobic monomer and a hydrophilic monomer. In a two step coating process, a hydrophilic polymer can be deposited on top of a previously deposited thin adhesion promoting layer. Some of these embodiments can involve coating with a UV polymerizable or UV cross linkable material. Cross linking is desirable in cases where one wants the hydrophilic layer to swell with water but not dissolve away by extended exposure to flowing /moving water.

WO 2010/020997 PCT/IN2009/000207 10 Other instances of grafting a hydrophilic monomer or polymer to the originally hydrophobic surface and other instances of coating a hydrophilic material or instances of combinations of grafting and coating (or grafting, coating and cross linking) are 'Within the scope of this invention. Other methods of rendering a hydrophobic surface hydrophilic are also within the scope of this iryention. In the embodiment in which indentations are formed on one or. more of the surfaces of the polymer substrate after being rendered hydrophilic, in one instance, the indentations are created along the surface by placing a roller with a number of protrusions over the surface and rolling the roller along the surface. In one instance, the corrugations of the polymer substrates after being rendered hydrophilic (and in one embodiment after having indentations formed on at least one surface) is performed by thermoforming.the corrugated polymer sheets to various corrugations diameters. Exemplary embodiments have corrugations with a radius of 5mm or curvature with a height of 5mm and a width of 10mm. However this is not a limitation of this invention. Typically corrugations run along the length (referred to as the x-axis) of the polymer sheet/substrate: Inone instance, some sheets are trimmed to a smaller size at an angle with respect to the x-axis in order to obtain a polymer sheet with corrugations running an angle respect to the resulting x-axis. In order to form a cartridge, the corrugated polymer substrates (after having their surfaces rendered hydrophilic) are fixedly secured to each other. In one instance, the corrugated polymer sheets/substrates are fixedly secured to each other at points of contact (apices) by means of a securing agent. The securing agent could be an adhesive or each corrugated polymer sheet/substrate could be spot welded by a suitable process (exemplary suitable process include, but are not limited to, hot-air welding, ultra sonic- welding and diode laser. transmission welding) to another- corrugated polymer sheet/substrate..: In one instance,, the process of fixedly securing one corrugated polymer sheet/substrate to another is performed sequentially until a cartridge including a number of sheets /substrates is formed. The process enables modularity since cartridges of various dimensions, length (height), breadth (width) and thickness (depth) can be formed. The adiabatic evaporative direct heat exchanger of this invention includes a number of polymer substrates, where a top and bottom surface of each substrate is rendered substantially hydrophilic, the -surfaces being originally hydrophobic.'. Each of the surfaces is corrugated to form a corrugated. polymer sheet. Each corrugated polymer sheet is disposed on an adjacent corrugated polymer sheet in a substantially parallel manner. For any two corrugated polymer sheets, one of the two being disposed on. other one of the two corrugated polymer sheets, corrugations on one corrugated polymer sheet are disposed at a predetermined' angle with respect 'to the corrugations on the other polymer sheet. The predetermined angle ranges from about 300 to about 90* WO 2010/020997 PCT/IN2009/000207 11 In one instance in the polymer substrate is a substantially flat sheet which can be obtained by a number of processes. In other instances, the polymer. substrate can be textured where the cross-section is not rectangular but wavy or corrugated. Exemplary processes include, but not limited to, extrusion and injection molding. Other processes are within the scope of this invention. In one instance, the hydrophobic polymer substrate is. a semi-crystalline polymer substrate. Exemplary embodiments include, but are not limited to, polyolefins such as polypropylene (PP), polyethylene and variants thereof, polyesters, such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), nylons, such as nylon 6, nylon 6,6 and others, biodegradable polymers (such as, but not limited to, PLA, PHA family of polymer with suitable copolymers, polycaprolactone and others) and other biodegradable materials. It should be noted that this invention is not limited to only the materials disclosed herein.. (Other materials such those disclosed in U.S Patents 5,852,078 and 5,496,910, both of which are incorporated by reference in their entirety, could be utilized.) In another instance, the hydrophobic polymer substrate is an amorphous polymer. Exemplary embodiments. of amorphous polymers include, but are limited to, polystyrene (PS) and PS copolymers, polymethylmethacrylate and other methacrylate polymers and copolymers. In one embodiment, the hydrophobic polymer substrate is obtained from an extruded thermoplastic hydrophobic polymer or from an injection molded thermoplastic hydrophobic polymer. (In some instances extrusion has a cost advantage.) In one instance, a number of indentations are formed on at least one of the two surfaces of each of the polymer substrates, after being rendered hydrophilic. The indentations can have different dimensions, length, breadth and depth. In one instance, not a limitation of this invention, the indentations have a depth of.0.02 mm. In one exemplary embodiment, not a limitation of this invention, the indentations have lengths of about 5 mm, a width of about 1 mm and a depth of about 0.02mm. The indentations effect additional strengths on the hydrophilic polymer sheets. The indentations also effect turbulence and water film thereby enhancing the effectiveness of the heat exchanger. By disposing each corrugated polymer sheet on another corrugated polymer sheet and fixedly securing one corrugated polymer sheet to another, channels or passageways (flutes) penetrating from one end of the adiabatic heat exchanger cartridge to another and similarly from the top of the adiabatic heat exchanger cartridge to the bottom of the adiabatic heat exchanger cartridge are formed. During operation, an evaporative liquid is provided from the top of the adiabatic heat exchanger cartridge. In one instance, the evaporative liquid is provided (sprayed) from the top using a distributor pad or spraying system (Figure 6b). The evaporative liquid would flow down due to gravity, flowing down the passageways and wetting their surfaces (thereby wetting the entire adiabatic heat WO 2010/020997 PCT/IN2009/000207 12 exchanger cartridge). The indentations provide turbulence to the evaporative liquid as well as increased its surface area of the evaporative liquid film on the surfaces of the adiabatic heat exchanger cartridge of this invention. A primary fluid travels through the passageways across the depth (thickness)) of the adiabatic heat exchanger cartridge of this invention. As the primary fluid travels through the passageways, the primary fluid comes into contact with the evaporative liquid film. The different angles at which the primary fluid and the evaporative liquid travels through the adiabatic heat exchanger cartridge of this invention add to the turbulence of both the primary fluid flow and the evaporative liquid. flow. The turbulence facilitates better evaporation of the evaporative liquid thereby cooling the primary fluid as it travels through (across) the'adiabatic heat exchanger cartridge. The process by which the primary fluid is cooled in the adiabatic heat exchanger/cartridge of this invention is described below in reference to Figure 7. Adiabatic cooling is a process by which the primary fluid is cooled without any change in the enthalpy levels of the primary fluid. There is no increase or reduction of total energy of the primary fluid, i.e., enthalpy. However during the process of adiabatic cooling, part of the sensible heat is converted into latent heat. During the process, the dry bulb temperature of the primary fluid is reduced. During the process both the Absolute humidity of air and the relative humidity of the primary fluid increase. Ambient air at temperature Db a, 'described in psychometric chart as point A. When this stream of the primary fluid comes into contact with the evaporative liquid, the contact facilitates evaporation of the evaporative liquid and increases in humidity. The primary fluid increases in humidity and is cooled, to nearly saturation levels. The end condition of the primary fluid stream is described in psychometric chart as point B, with dry bulb temperature at Db b. The humidity level in the primary fluid has increased from Ah a to Ah b. The result is adiabatic cooling without change in Enthalpy. In one exemplary embodiment, this invention not be limited only to that exemplary embodiment, the adiabatic direct heat exchanger of this' invention includes a number of extruded polypropylene (PP) substrates. The surfaces of the PP substrates are plasma treated (in some instances dried afterward) and a hydrophilic monomer/polymer grafted' on to the treated surface (as described herein above). Indentations are created along one or more of the surfaces of the PP substrates, after being rendered substantially hydrophilic, by means of rollers. In the exemplary embodiment, this invention not been limited only to that embodiment, the indentations are about 5 mm in length, 1 mm in width and about 0.02 mm in depth. The hydrophilic PP substrates, after having indentations produced on at 'least one surface, are corrugated by thermoforming. The corrugations have radii of about 4 mm to about 10 mm or curvatures with a width and height of 4 to 1,0mm (this invention not been limited to only those diameters or dimensions). The corrugated hydrophilic PP substrates are then disposed one on another, the corrugations on one corrugated hydrophilic PP substrate being at a predetermined angle respect to the corrugations on the adjacent corrugated WO 2010/020997 PCT/IN2009/000207 13 hydcrophilic PP substrate disposed below. The predetermined angle ranges from about 300 to abput 90". Each corrugated hydrophilic PP substrate is spot welded to the corrugated hydrophilic PP substrate disposed underneath. The process. results in the adiabatic heat exchanger cartridge that is roughly a cuboid of predetermined dimensions in length (height), width (breadth) and depth (thickness). In the exemplary embodiment the evaporative liquid is water and the primary fluid is air. The breadth times the length (also referred to as width times the height) provides the area receiving the airflow and the depth (thickness) defines the direction and flow time inside the adiabatic heat exchanger cartridge. Figure 6b shows an isometric view of a typical application of the adiabatic heat exchanger cartridge. In the exemplary embodiment, primary fluid air travels horizontally across the depth through the flutes, while the evaporative fluid, water distributed through the distributor pad flows down due to gravity. In one embodiment, the adiabatic direct heat exchanger of this invention is utilized in an indirect/direct evaporative cooling apparatus. Indirect/direct evaporative coolers (IDEC) are two stage evaporative coolers that are systems deploying sensible cooling (described below) without moisture addition in the first stage and evaporative cooling in the second stage. In other embodiments, the adiabatic direct heat exchanger of this invention can be utilized alone (as in a swamp cooler) or in a multistage cooling apparatus also including additional cooling components such as cooling coils or heat pipes. The two stage IDEC cooling apparatus utilizing the adiabatic heat exchanger of this invention is described hereinbelow. Sensible cooling is a process by which air is cooled without any change in the absolute humidity, or level of water vapor. There is neither any gain nor loss of absolute humidity. As shown in the conventional psychometric chart, Fig. 8, the process of cooling of primary air is shown from point A to Point B. Such sensible cooling is achieved by having another. stream of secondary air taking the path from C to D. As the secondary air stream is made to flow in alternate wet channels having thin 'water film' formed over treated surface, it collects moisture due to vaporization of water film and a rise in its temperature. This process is depicted from point C to D in Fig.8. In one embodiment, the two-stage evaporative cooling apparatus of this invention includes an indirect evaporative cooling component (heat exchanger), which in one instance can be a conventional indirect evaporative cooling component such as described in US patents US 6,931,883 (the '833 patent) and US 5,664,433 (the '433 patent), both of which are incorporated by reference herein in their entirety, and an adiabatic direct evaporative cooling component of this invention, as described herein above. (The indirect evaporative cooling component can also be a nonconventional indirect evaporative cooling component as described herein below.) In one instance, the two-stage evaporative cooling apparatus of this invention includes a primary fluid supply component, located upstream from the indirect WO 2010/020997 PCT/IN2009/000207 14 evaporative cooling component of this invention and supplying the primary fluid. to the indirect evaporative cooling component of this invention. During operation the primary fluid supply component draws ambient fluid through a filtering component and supplies filtered ambient fluid as the primary fluid. The filtering component can include one of a variety of filters (including but not limited to conventional filters, carbon filters, electrostatic filters, etc.). A first evaporative liquid supply system supplies the evaporative liquid to the indirect evaporative cooling -component of this invention. A second evaporative liquid supply system supplies the other evaporative liquid to the direct adiabatic evaporative cooling component. Inone instance, a liquid holding component (such as a tank) provides a supply of the evaporative liquid and the other evaporative liquid. The first evaporative liquid supply system (a pump in one instance) and the second evaporative liquid supply -system (another pump. in one instance) are disposed inside the liquid holding component. The first evaporative liquid supply system, the second evaporative liquid supply system and a liquid holding component are comprised of aseptic material. A liquid disinfection system can. be disposed to receive the evaporative liquid and the other evaporative liquid and render both of them disinfected. In one embodiment the liquid disinfection system includes a system utilizing ultraviolet (UV) radiation in order to disinfect the evaporative liquid on the other evaporative liquid. It should 'be noted that other liquid disinfecting systems, such as, but not limited to, system utilizing ozone and other liquid disinfecting systems are within the scope of this invention. In another instance, the first and second evaporative liquid supply systems include an ultrasonic humidifier that supplies the first and second evaporative liquids in a mist form to, the indirect and direct evaporative heat exchanger's (cooling components) In yet another instance, the two-stage evaporative cooling apparatus of this invention includes a housing enclosing the filtering component the primary fluid supply component, the liquid holding component the first evaporative liquid supply system, the second operated liquid supply system, the liquid disinfection system and connecting components operatively connecting the systems and other components. The housing and the connecting components are comprised of an aseptic material. In one embodiment, the two-stage evaporative cooling apparatus of this invention is controlled through a controller (in one instance, a microprocessor-based controller although other processor based controllers are within the scope of this invention). In that embodiment, the two-stage evaporative cooling apparatus of this invention includes, as shown in Figure 18, one or more processors 30 and one or more computer usable media 80 having computer readable code embodied therein to cause the one or more processors to control the apparatus. The-one or more processors and the one or more- computer usable media are operatively connected by an interconnection component 70 (such as a 'computer bus). A signal/control interface 75 received/sends signals and control signals from/to monitoring systems/pump drivers/other drivers for the two-stage evaporative WO 2010/020997 PCT/IN2009/000207 15 cooling apparatus. In one instance, the one or more computer readable media has computer usable code embodied therein for causing the one or more processors to: obtain data to determine whether there is at least a predetermined amount of liquid in the liquid holding component; provide, after determining that there is at least the predetermined amount of liquid in the liquid holding component, operating signals to the first evaporative liquid supply component and the second evaporative liquid supply component; the operating signals enabling operation of the first and second evaporative liquid supply components for a predetermined time interval in order to substantially disinfect the evaporative liquid and the another evaporative liquid and in order to distribute the evaporative liquid to the indirect evaporative cooling component and the another evaporative liquid to the direct evaporative cooling component; and provide other operating signals to the primary fluid supply component, the other operating signals enabling operation of. the primary fluid supply component in order to supply the primary fluid to the indirect evaporative cooling.L By controlling and enabling operation of the evaporative liquid supply components and in controlling and enabling operation of the primary fluid supply component, the computer readable code can cause the one or more processors 30 to control humidity (by means of controlling the other evaporative liquid supply component) and to control temperature, by also controlling the primary fluid supply component). In one instance, the primary fluid in two-stage evaporative cooling apparatus of this invention, -after flowing through the direct adiabatic evaporative cooling component is provided to an enclosure. The two-stage evaporative cooling apparatus of this invention, in that instance can include an exhaust system for removing fluid from the enclosure. The exhaust system can include, for example; a number of fans. In that instance, the computer usable media can have computer readable code that causes the one or more processors to provide yet other operating signals to the exhaust system to enable operation of the exhaust system when primary fluid is provided to the enclosure. In order to better illustrate the present invention, one detailed exemplary embodiment is presented below. In the detailed exemplary embodiment, the primary fluid and the secondary fluid are both air, referred to as primary air and secondary air, and the evaporative liquid and the other evaporative liquid are both water. While in the embodiments presented hereinbelow detailed dimensions are present, these dimensions are not limitations of this invention.. As shown in Fig. 9 (which is the vertical cross sectional schematic view of the embodiment of the invention showing its main parts), and Fig. 10 (which is the horizontal cross sectional schematic view of the embodiment showing water distribution, air flow pattern and other parts), the embodiment is an integrated WO 2010/020997 PCT/IN2009/000207 16 system, housed in a metallic casing 1 constructed out of weather protected and insulated wall panels to protect against atmospheric corrosion and energy loss to ambient by thermal conduction. The unit comprises the following components: 1. An air propelling system, comprising air filters 2 to remove dust particles, a blower 3, drive motor 4, Pulleys 5 and belts 6; 2. A heat exchange system, comprising a first indirect * evaporative component (heat exchanger), (HE-I) 7, and a second stage heat exchanger (HE-II) 8, an embodiment of the direct adiabatic evaporative component of this invention The second stage heat exchanger HE-IL 8 is an adiabatic heat-exchanger of this invention, as described hereinabove and shown in Figures 1-7, where a required amount of moisture is added to cool the primary air to a desired temperature, up to the maximum possible by adiabatic saturation. The second stage heat exchanger HE-lI 8 is also housed in an aseptic common housing 9 created by using structural Sections made of aseptic material such as stainless steel, and located above the water tank 14 made of aseptic material. 3. Passages for air: Canvas duct-I 10 and Air plenum duct-I 11 connect the blower with HE-I 7. HE-I 7 and the HE-Il 8 are housed in a common housing. Air plenum duct-II 12 and Canvas duct-IL 13 connect the air cooling system to the cooled air distribution system of the living space 29 shown in Fig. 12 4. Water distribution system: As shown in Fig. 11, the Water distribution system consists of a submersible pump 16 dedicated to meet the requirements of HE-I 7 and a separate submersible pump 17 dedicated to meet the requirements of HE-II 8. These pumps are made of aseptic material like Stainless steel and are located in the water tank 14 (shown in Fig. 9). To achieve better controllability, enhance performance reliability and achieve energy efficiency, HE-I 7 and the adiabatic direct evaporative heat exchanger 8 are provided with independent pumps 16, 17 to distribute varying amount of water at varying pressures 5. Pipes and misting systems: As shown in Fig 10 and Fig 11, PVC piping-I 18 and water distribution cartridge 19 fitted with misting systems are provided to uniformly spray water over HE-I 7 elements. Similarly PVC piping-IL 20 and water distribution cartridge 21 fitted with misting systems are provided to uniformly spray water over HE-II elements. An embodiment of the misting system 35 is shown in Figure 13d. A close view of the embodiment of water distribution cartridge 19 is shown in Figure 13d as 34, with the misting system detailed as 35 and the water spray as 36, WO 2010/020997 PCT/IN2009/000207 17 6. Water disinfection system: As shown in Fig. 10, Fig. 11 an ultraviolet (UV) system 22 is provided to ensure disinfection of the circulating water. 7. Materials The Water tank' 14 of the apparatus, water pump 16, 17 and piping system component 18, 20 are constructed of aseptic materials. With reference to Figs. 9, 10 and 11, the working principle of the invention is explained here in below: Ambient primary air 23 is drawn across filters 2 of appropriate specification by a blower system comprising a blower 3, motor 4, pulley 5, and belts 6; this blower is connected by a Canvas duct-I 10, to a plenum duct-I 11 for equal distribution of air across HE-I 7. As shown in Fig. 10 and Fig. 11, the submersible pumps 16 and 17 pump water from water tank 14 to distribution cartridges 19, 21 through the Polymer piping 18, 20 to ensure uniform mist of water spray over HE-I 7 and HE-II 8 respectively. An on line UV system continuously keeps the circulated water in disinfected condition As shown in Figure 12, filtered and cooled/treated primary air 25 is delivered across the living space 29 to be cooled, which, in'turn, picks up heat from the living space 29 and is exhausted out through an exhaust system 28 provided in the closed space 29 to be conditioned. This entire process is controlled through a pre programmed micro controller 30 (see Fig. 18) based control system that senses the signals and operates/ controls the system. When the system is switched on, the controller checks if there is adequate water in the tank 14, upon sufficient level, it switches the pumps 16, 17 on for a defined' period, so that the water in the tank is treated by the UV system 22, as well as uniform wetting of the HE-I 7 Heat exchanger and the medium of HE-I heat exchanger 8. Subsequently it switches the blower 3 on, to blow- the filtered air 23 through the heat exchangers. In another embodiment, the indirect evaporative cooling heat exchanger is not conventional and includes one or more modules. Each module includes a number of units. Taking two units from the number of units, each unit from the two units includes a first polymer substrate and a second polymer substrate. In one instance, this invention not being limited to only that instance, the first and second polymer substrates are comprised of an extruded thermoplastic polymer such as extruded polypropylene (PP). One surface of each of the first and second polymer substrates is rendered substantially hydrophilic while the other surface of the first and second polymer substrates is substantially hydrophobic. (Before one surface is rendered substantially hydrophilic, both surfaces of the first and second polymer substrates are substantially hydrophobic.) The rendering of one surface WO 2010/020997 PCT/IN2009/000207 18 substantially hydrophilic is. obtained, in one instance,. by Corona treating the surface. In other instances, the surface is rendered substantially hydrophilic by a method such as plasma discharge, plasma jet flame treatment or acid etching. This invention is not limited to only those instances of the method of rendering a surface substantially hydrophilic. A substantially compliant nonwoven material is disposed on and fixedly attached at a number of locations to the hydrophilic surface of the first polymer substrate. Similarly, substantially compliant nonwoven material is also disposed on and fixedly attached at a number of locations to the hydrophilic surface of the second polymer substrate. The substantially compliant nonwoven material can be a spunbonded material, a melt blown material, hydroentangled (spunlaced) material or made through any other processes such as co-forming, airlaying, wetlaying, carding webs, thermal bonding, needle punching, chemically- bonding or combinations thereof. Embodiments of spunbonded material include polyolefin, Polyethylene terephthalate (PET) and nylon. Embodiments of melt blown material include polyolefin, Polyethylene terephthalate (PET) and nylon. Embodiments of hydroentangled material include cotton, raybn or viscose staple fiber, lyocell staple fiber, polyolefin staple fiber, polyester staple fiber and nylon staple fiber. Nonwoven materials are typically made from fibers or filaments. Typically, these are made as a very thin web with a very low density described as GSM (grams per square meter). The lower the density, the thinner the nonwoven web. The structure of the nonwoven web consists of a three dimensional non- uniform -arrangement of the fibers/filaments in various orientations. While not desiring to be bound by theory, in one explanation, the non- uniform three dimensional texture structure results in empty spaces which can create channels or paths for-air and other fluids such as water to pass through under suitable conditions. These pathways make the nonwoven webs porous and the pores do not have a single size but a distribution. Low density nonwoven webs can often have high porosity. Nonwoven webs can be formed from fibers and filaments based on hydrophobic or hydrophilic polymers. Representative, but not complete, examples of polymers that are hydrophobic for making nonwoven webs are polyolefins and polyethylene terephthalate. Representative, but not complete, examples of hydrophilic polymers for making nonwoven webs include cellulosic materials like cotton, rayon or viscose etc. Under suitable conditions of porosity, fiber/filament diameter, density (GSM) etc, significant capillary action and wicking of water can occur in a web. The porosity of.certain porous nonwoven webs can often be sufficient to enable the easy transport of water and other fluids because of wicking caused by capillary. action. In the case of a nonwoven web made from hydrophilic polymers, some of the water will swell the fibers and the rest will go around and over the fibers. Porous low density nonwoven webs made from hydrophobic fibers or filaments can transfer water through wicking action. Water can flow along, around and over but not through the hydrophobic polymer fibers. The porosity and associated wicking action by a porous nonwoven web can render the nonwoven web effectively hydrophilic in terms of its capability to be wet-and easily spread water WO 2010/020997 PCT/IN2009/000207 19 even if the fibers or filaments constituting the nonwoven web are made from -hydrophobic polymers. The first and second polymer substrates are adjacent to each other and have a number of channels disposed between them. The channels are attached to the hydrophobic surface of the first polymer substrate and to the hydrophobic surface of the second polymer substrate. In one instance, the first and second polymer substrates and the channels disposed between them comprise an extruded polymer unit. It should be noted that other configurations, besides an extruded polymer unit, resulting in first and second polymer substrates and channels disposed between them are also within the scope of this invention. Figures 17ab,c and d depicts several configurations (embodiments) of the channels disposed between the hydrophobic surfaces of the substrates. The two polymer substrates, having channels disposed between and fixedly attaching the two hydrophobic surfaces to each other and having exterior surfaces that have been rendered hydrophilic and having nonwoven material disposed on and fixedly attached at number of locations, comprise one unit.*One embodiment of a unit is shown in Figure 14a and 14b. Referring to Figure 14b, two substrates 31 have a number of channels 38 & 39 disposed between them. It should be-noted that the steps for producing such unit can be performed in different sequences. The two substrates can have the channels disposed between them and attached to each of two surfaces (the surface is being naturally hydrophobic) and the outside surfaces can be rendered substantially hydrophilic and nonwoven material attached to a number of locations on each of the hydrophilic surfaces. Similarly, the substrate can be rendered hydrophilic and then, the hydrophobic surfaces have the channels disposed between them and attached-to each of the two surfaces. This invention is not limited to one of these two methods. After forming the two or more units, two or more polymer strips are interposed between'two units and fixedly secured to each of the hydrophilic surfaces (or equivalently, to the nonwoven material disposed on the hydrophilic surface) of each unit. In one instance, adhesive is disposed between each of the polymer strips and each of the two adjacent units in order to fixedly secure the polymer strip to the hydrophobic surface of -each unit. The two units with the two or more polymer strips interposed between them form one module of the heat exchanger. Embodiments of the module of the heat exchanger are shown in Figure 16a and 16b. Referring to Figure 16b, two units 40, 41 have two or more polymer strips 33 separating the two units 40, 41 and fixedly attached to each of the hydrophilic surfaces having the nonwoven material 32 disposed on the surface. The configuration in Figures 16a, 16b corresponds to a cross flow heat exchanger. In the cross flow heat exchanger, each channel 38 is disposed substantially perpendicular to each polymer strip 33. The two units 40, 41 with the polymer strips separating the two units 40, 41, the polymer strips being fixedly attached to WO 2010/020997 PCT/IN2009/000207 20 the nonwoven material 32 disposed on the hydrophilic surface of each of the units 40, 41 form one module of the heat exchanger. A number of modules can be brought together to make an indirect heat exchanger cartridge' as referred to in Figures16c, 16d and 16e. A number of indirect heat exchanger cartridges can be assembled together to increase the total capacity in a modular manner. The indirect heat exchanger cartridges can be stacked together or positioned, side-by side (or any other configuration) in a modular manner and fixedly secured (a number of mattei-s of fixedly securing the modules, such as adhesive, external structures, etc. are within the scope of these teachings) to each other to form an indirect heat exchanger cartridge. Furthermore the indirect heat exchanger cartridges can be stacked together, placed side by side or any other configuration and secured to each other to obtain a heat exchanger. (One embodiment of an indirect heat exchanger cartridge of this invention is. shown in Figure 13a. Although one indirect heat exchanger cartridge could be used as an indirect evaporative cooling heat exchanger as shown in Fig. 13a, two cartridges could be stacked together, one on top of the other, preserving the same primary and secondary fluid flow patterns. In the embodiment where .the indirect heat exchanger cartridges are stacked vertically, two indirect heat exchanger cartridges could share one evaporative fluid distribution component. . In another embodiment, the indirect heat exchanger. cartridges can be kept one beside the other, side by side, thus facilitating modular increase and making a large system. In another embodiment two indirect heat exchanger cartridges are placed one downstream to the other with the primary fluid flowing from one cartridge to the one placed down stream. It should be noted that providing the number of modules and fixedly attaching, in a predetermined configuration, one module to another module in a number of modules provides a method for providing a scalable indirect evaporative cooling components. The embodiment (indirect heat exchanger cartridge) shown in Figure 16d enables scaling up the- indirect evaporative cooling component of this invention and scaling up the indirect evaporative cooling component in the evaporative cooling apparatus of this invention. Two units 40, 41 with two or more polymer strips 33 (spacers) interposed between them and fixedly secured to each of the units 40, 41 becomes a module. Each module from a number of modules is fixedly attached to another module, forming an indirect heat exchanger Cartridge. . As described hereinabove, although one cartridge could- be used as an indirect evaporative cooling heat exchanger in an IDEC, multiple numbers of indirect heat exchanger cartridges can be used to make one indirect evaporative cooling heat exchanger in an IDEC of different dimensions. During operation, an evaporative liquid is distributed to the substantially compliant nonwoven material of each of the hydrophilic surfaces of the unit and a fluid flows within a space separating each of the units with heat being exchanged between the evaporative liquid and the fluid, and another fluid. flowing through at least some channels from the number of channels. The other fluid exchanges heat with the hydrophilic surface. (Heat is transferred from the nonwoven material to the hydrophilic surface and through the substrate to the hydrophobic surface). In WO 2010/020997 PCT/IN2009/000207 21 one instance, the fluids are air, and the heat exchanger has moist air from the evaporated cooling of the substantially compliant nonwoven material having the evaporative liquid distributed over and dry air flowing through the channels and being cooled.' In that instance to the non-conventional heat exchanger is referred to as a Dry Air, Moist Air (DAMA) heat exchanger. In one instance, the embodiment of the non-conventional indirect evaporative heat exchanger of this invention described herein above, in order to substantially fixedly attached the substantially compliant nonwoven material to the hydrophilic surface of one of the substrates, a thermoplastic material is disposed at the number of locations at which the nonwoven material is going to be fixedly attached to the hydrophilic surface. The substantially compliant nonwoven material is fusion bonded at the number of locations to the hydrophilic surface. In one embodiment, not a limitation of this invention, the thermoplastic material is low-density polyethylene (LDPE). In one embodiment, not a limitation of this invention, each one of the first and second polymer substrates 31 has a thickness of at most about 0.12 mm (or, alternatively, 0.12- mm to within engineering tolerances). In one'instance, the nonwoven materials have a density of at most about 30 g per square meter (or, alternatively, 30 g per square meter to within engineering tolerances). An exemplary detailed embodiment of the non-conventional indirect evaporative heat exchanger is disclosed below. An embodiment of the non-conventional indirect evaporative heat exchanger HE-I 7 (referred to as HE-I DAMA or as DAMA), shown in Figures 13a-13c and 16a-16e, has defined passages for two streams of air 23 and 26 without the two streams coming in contact. One embodiment of the HE-I DAMA 7 is shown in Figure 13a and 16d. The main stream of air, primary air 23 is guided along the defined channels/ paths. Alternate channels; provide a passage for another stream of -air, secondary air 26.These alternate channels provide for water passage in the other direction. As the water flows, they form a film on either side of the alternate passage. In DAMA 7 heat exchanger primary air 23 is cooled by a second stream of air 26 passing through the alternate passages. The input primary air 23 comes out of the DAMA 7 heat exchanger as sensibly cooled air 24 The secondary air 26 is a part of the primary air 23 which is cooled- in stage I and stage 2 and is an appropriate percentage boot strapped and routed through the alternate passages of HE 1 DAMA 7, as shown in Figure 9. In one instance, the secondary air amounting to, in this embodiment, but 'not a limitation of this invention, about 40 % of the primary air is boot strapped from the main stream primary air after it passed through both the first stage DAMA 7 and second stage heat exchanger 8 and routed through the alternate wet channels to cool the primary air. This secondary air 26 passes through the alternate passages of DAMA 7 and evaporates the water film formed by the water distribution indirect heat exchanger cartridge 19. Thus the secondary air gains in both in enthalpy and in absolute WO 2010/020997 PCT/IN2009/000207 22 humidity. The heat required for the evaporation of this water film is obtained from the primary air 23 through thin walls of DAMA 7. Thus the primary air 23 is cooled sensibly by the vaporizing moisture of water film in alternate passages. This secondary air 26 is exhausted through a secondary air hood 15 as secondary outlet air 27. The Primary air passes horizontally through the defined paths (channels) 38, formed in thin walled extruded poly propylene sections (see 'Figures 14a-14b). Water flows from top to bottom down wards in 'the alternate secondary air channels 42 (Fig. 16b) and secondary exhaust air flows from bottom to top, in this secondary channels 42, thus achieving cross flow functionality of the sensible heat exchanger. The absence of non cellulose materials in unitized cartridges of the DAMA heat exchanger avoids harmful fungus / bacterial growth. The adiabatic direct heat exchanger cartridge utilizes polymer substrates which are antibacterial While the above described embodiments of the evaporative cooling system of this invention, including the above described exemplary embodiment of the evaporative cooling system of this invention, are two-stage evaporative cooling systems, it should .be noted that multistage evaporative cooling systems are also within the scope of this invention. The above described embodiments can be generalized to obtain multistage cooling system embodiments, which may have other heat exchangers, including but not limited to cooling coils, heat pipes, heat recovery wheels, desiccant dehumidification components., Each computer program within the scope of the claims below may be implemented in any programming language, such as assembly language, machine language, a high-level procedural programming language, or an object-oriented, programming language. The programming language may be a compiled or interpreted programming language. Each computer program may be implemented in a computer program product tangibly embodied in a computer-readable storage device for execution by a computer processor. Method steps of the invention may be performed by a computer processor executing a program tangibly embodied on a computer readable medium to perform functions of the invention by operating on input and generating output. Common forms of computer-readable media include, for example, a, floppy disk, a flexible disk, hard disk, magnetic tape, or any other magnetic medium, a CDROM, any other optical medium, punched cards, paper tape, any other physical medium with patterns of holes, a RAM, a PROM, and EPROM, a FLASH-EPROM, any other memory chip or cartridge, or any other medium from which a computer can read. From a technological standpoint, a signal or carrier wave (such as used for Internet distribution of software or remote management of devices) encoded with functional descriptive material is similar to. a computer readable medium encoded with functional descriptive material, in that they both WO 2010/020997 PCT/IN2009/000207 23 create a functional interrelationship with a computer. In other words, a computer is able to execute the encoded functions, regardless of whether the format, is a disk or a signal. In one instance, the one or more processors 30 can include.server and client processors and. the computer usable media can include the necessary -software components to implement and support a distributed application such as remote management of the components of the indirect/direct evaporative cooling apparatus of this invention (such software can include, for example, but not limited to, DCOM or CORBA, or Web server/browser and third-party applications, such as, ColdFusionTm/ShockWave T M ). Although this invention has been described with respect to various embodiments, it should be realized this invention is also capable of a wide variety of further and other embodiments within the spirit and scope of this invention.

Claims (26)

1.A heat exchanger comprising; a plurality of polymer substrates, each polymer substrate having a top and bottom surface; said top surface and said bottom surface being treated to render said top surface and said bottom surface substantially hydrophilic; each one of said plurality of substrates being corrugated, said each one constituting a corrugated polymer sheet from a plurality of corrugated polymer sheets; each one corrugated polymer sheet being disposed on an adjacent corrugated polymer sheet in a substantially parallel manner; for any two polymer sheets, from said plurality of corrugated polymer sheets, one of said two polymer sheets being disposed on another one of said two polymer sheets, corrugations on said one corrugated polymer sheet are disposed at a predetermined angle to corrugations on said another one.

2. The heat exchanger of claim 1 wherein one surface from each said top and bottom surface has a plurality of indentations disposed therein.

- 3. The heat exchanger of claim 2 wherein each indentation from said plurality of - indentations has a depth of at-most about 0.02 mm.

4. The heat exchanger of claim I wherein said polymer substrates are comprised of a thermoplastic polymer.

5. The heat exchanger of claim 4 wherein said thermoplastic polymer is an extruded thermoplastic polymer.

6. The heat exchanger of claim 1 wherein said polymer substrates are comprised of a semi-crystalline polymer.

7. The heat exchanger of claim 6 wherein said semi-crystalline polymer is selected from a polyolefin, polyester, nylon, polylactide (PLA) and Polyhydroxyalkanoate (PHA).

8. The heat exchanger of claim 6 wherein said semicrystalline polymer is a biodegradable polymer. WO 2010/020997 PCT/IN2009/000207 25

9. The heat exchanger of claim.1 wherein said predetermined angle is an angle between about 30' to about 900.

10. A method for manufacturing an adiabatic evaporative heat exchanger, .the method comprising the'steps of: a) rendering both surfaces of each one of at least two polymer substrates hydrophilic, b) corrugating said each one of said.at least two polymer substrates; c) disposing one of said at least two corrugated polymer substrates on another one of said at least two polymer substrates, corrugations on said one.corrugated polymer substrate being disposed at a predetermined angle to corrugations on said another one of said at least two polymer substrates; and d) fixedly securing said one of said at least two corrugated polymer substrates to said another one of said at least two polymer substrates.

11. The method of claim 10 wherein the step of fixedly securing further comprises the step of fixedly securing, at least at some apices of the corrugations, said one of said at least two corrugated polymer substrates to said another one of said at least two polymer substrates.

12. The method of claim 10 wherein the step of corrugating said each one of-said at least two polymer substrates is performed after both surfaces of said each one, of said at least two polymer substrates are rendered hydrophilic.

13. The method of claim 10 wherein said at least two polymer substrates comprises a plurality of polymer substrates.

14. The method of claim 10 further comprising the step of forming a plurality of indentations on at least one surface of each of said at least two polymer substrates.

15. The method of claim 14 wherein the step of forming the plurality of indentations is performed after both surfaces of said each one of said at least two polymer substrates are rendered hydrophilic and before the step of corrugating said each one of the at least two polymer substrates.

16. The method of claim 14 wherein the step of forming a plurality of indentations comprises the steps of: WO 2010/020997 PCT/IN2009/000207 26 providing a roller with a plurality of protrusions; placing the roller over said at least one surface; and rolling the roller along said at least one surface.

17. An evaporative cooling apparatus comprising: an indirect evaporative cooling component; and a direct cooling component. comprising; a plurality of polymer substrates, each polymer substrate having a top and bottom surface; said top surface and said bottom surface being treated to render said top surface and said bottom surface substantially. hydrophilic; each one of said plurality of substrates being corrugated, said each one constituting a corrugated polymer sheet from a plurality of corrugated polymer sheets; each one corrugated polymer sheet being disposed on an adjacent corrugated polymer sheet in a substantially parallel manner; for.any two polymer sheets, from said plurality of corrugated polymer sheets, one of said two polymer sheets being disposed on another one of said two polymer sheets, corrugations on said one corrugated polymer sheet are disposed at a predetermined angle to corrugations on said another one; the direct cooling component being positioned downstream from the indirect cooling component and receiving at least a portion of a primary fluid from the indirect cooling component.

18. The evaporative cooling apparatus of claim 17 wherein, in the direct cooling component, one surface from each said top and bottom surface has a plurality of indentations disposed therein. WO 2010/020997 PCT/IN2009/000207 27

19. The evaporative cooling apparatus of claim 18 wherein, in the direct cooling component, each indentation from said plurality of indentations has a depth of at most about 0.02 mm.

20. The evaporative cooling apparatus of claim 17 wherein, in the direct cooling component, said polymer substrates are comprised of a thermoplastic polymer.

21. The evaporative cooling apparatus of claim 20 wherein, in the direct cooling component, said thermoplastic polymer is an extruded thermoplastic polymer.

22. The evaporative cooling apparatus of claim 17 wherein, in the direct cooling component, said polymer substrates are comprised of a semi-crystalline polymer.

23. The evaporative cooling apparatus of claim 22 wherein, in the direct cooling component, said semi-crystalline polymer is selected from a polyolefin, polyester, nylon, polylactide (PLA) and Polyhydroxyalkanoate (PHA).

24. The evaporative cooling apparatus of claim 22 wherein, in the direct cooling component, said semicrystalline polymer is a biodegradable polymer.

25. The evaporative cooling apparatus of claim 17 wherein, in the direct cooling component, said predetermined angle is an angle between about 30 to about.90".

26. The evaporative cooling apparatus of claim 17 wherein-the indirect evaporative cooling component comprises: at least one module, said at least one module comprising: a plurality of units, each unit from at least two of said plurality of units comprising: a first polymer substrate; one surface of said first polymer substrate being rendered substantially hydrophilic; another surface of said first polymer substrate being substantially hydrophobic; a second polymer substrate; one surface of said second polymer substrate being rendered substantially . hydrophilic; another surface of said second polymer substrate being substantially hydrophobic; said first polymer substrate and said second polymer substrate being adjacent one another and having a WO 2010/020997 PCT/IN2009/000207 28 plurality of channels disposed between and attached to said another surface of said first polymer substrate and said another surface of said second polymer substrate; a first substantially compliant nonwoven material being disposed on and substantially fixedly attached at a plurality of locations on said one surface of said first polymer substrate; and a second substantially compliant nonwoven material being disposed on and substantially fixedly attached to at another plurality of locations on said one surface of the second polymer substrate; and at least two polymer strips interposed between and fixedly securing together two adjacent units from said at least two units from said plurality of units such that said to adjacent units are separated one from another.