US20120047937A1

US20120047937A1 - Indirect Evaporative Cooling System

Info

Publication number: US20120047937A1
Application number: US12/862,295
Authority: US
Inventors: James David Cass
Original assignee: Individual
Current assignee: Individual
Priority date: 2010-08-24
Filing date: 2010-08-24
Publication date: 2012-03-01

Abstract

A light weight, mobile, cost effective indirect evaporative air/gas cooling system. Porous light weight high strength polypropylene plastic plates are used for dry air conduction while the spaces between neighboring plates filled with highly breathable fabric sheets or fibers are used for wet air conduction. Waters are sprayed onto the plates and the spacing fabrics. Water evaporation is accelerated by an air exhaustion facility on top of the wet air channels which exhausts the humid air from the cooling system.

Description

DESCRIPTION OF RELATED ART

The present application relates to evaporative air cooling system, and more particularly to indirect evaporative air cooling system that is highly efficient, cost effective, and green energy powered.
Note that the points discussed below may reflect the hindsight gained from the disclosed inventions, and are not necessarily admitted to be prior art.
An evaporative air cooling system is a device that cools air through evaporation of water. It does not use a refrigerant compressor-and is thus significantly more energy efficient than conventional air conditioning systems.
Evaporative cooling is especially well suited for areas where the air is hot and humidity is low. For example in the United States, the western/mountain cities like Denver, Salt Lake where sufficient water is available, evaporative air conditioning is very popular. In these dry, arid climates, the installation and operating cost of an evaporative cooler can be as much as 80% lower than refrigerative air conditioning. However, because direct evaporative cooling dramatically increases the humidity of the cooled air, which may cause discomfort, often indirect evaporative cooling systems are more suitable for residential use.
Indirect evaporative cooling is typically accomplished by passing two air streams through a system comprising thin parallel heat exchange plates with alternating dry and wet passages. Primary air stream, to be cooled, is passed through the dry passages; simultaneously, a secondary air stream is passed through the parallel wet passages. The temperature difference between the primary and secondary air streams drives the heat flow from dry air passages to the wet air passages. The secondary air stream comes in direct contact with the water in the wet passages, accelerating the water vaporization, extracting the required latent heat from the heat exchange plates, thereby cooling the plates, and the passing primary air in the dry passages.
A number of indirect evaporative heat exchangers have been designed. Generally to enhance the heat exchange, they use specially treated plates that are coated with a water-conducting wick material on one side, with a low permeable material on the other side. The low permeable sides between two neighboring plates form the dry air way while the wick material sides between the next two neighboring plates form the alternating wet air way. For example, US 2005/0218535 A1 describes an indirect heat exchanger with heat exchange plates being coated with a water-conducting layer of materials, such as, cellulose, polyester fibers while the other side is covered with layer of plastic or other low permeable material. The water conducting material may be mixed with material that is water impermeable, such as polyethylene, for structure support.
Another example, WO 2010/010576 A1 describes an indirect evaporative heat exchanger using specially treated plates that are hydrophobic on one side and hydrophilic on the other side.
These specially treated heat exchange plates significantly increase the manufacturing cost and thus the price of the cooler device. For example, a Coolerado™ cooler has a price of $5000-$7000. This formidable price range is prohibitive for most consumers.

SUMMARY

The present application discloses a novel and improved indirect evaporative heat exchanger.
In one aspect of an embodiment, plastic plates of porous structure and sufficient thickness are used for dry air passages. The porous structure inside the plates comprises numerous thin bubble-like structure, forming the dry air passages for production air to travel through. Inside the plates the production air travels zigzagly through the numerous thin pores for efficient heat exchange.
In one aspect of an embodiment, thin sheets of breathable fabrics are placed between the plastic plates to form wet air passages. Water is directly and constantly sprayed on the breathable fabrics and on the outside of the plastic plates while air is blown through the inter spaces and the breathable fabric sheets between the plastic plates to cool the plates.
With this simple structure, production air is never directly in contact with water and is cooled by going through the porous plastic plates. The placing of the breathable fabrics between the plates allows the air to go through and water to evaporate efficiently, thereby extracting heat from the surrounding plates and the production air inside the plates.
The plates and breathable fabrics do not need to be specially chemically treated, are currently commercially available. The structure is also highly scalable, can be made bigger or smaller, depending on the purpose of use. The cooler can be organized in units and assembled in different number of units according to needs when in use.
Since no expensive materials are needed, the cost of the cooling system is dramatically reduced.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosed inventions will be described with reference to the accompanying drawings, which show important sample embodiments of the invention and which are incorporated in the specification hereof by reference, wherein:

FIG. 1 shows top view of an example indirect evaporative cooler in accordance with this application.

FIG. 2 shows a side view of the production air entrance of an example indirect evaporative cooler in accordance with this application.

FIG. 3 shows a prospective view of an example heat exchange unit of an example indirect evaporative cooler in accordance with this application.

FIG. 4 shows a cross section view of an example dry/production air passages of an inside of a plastic plate in accordance with this application.

FIG. 5 shows a cross section view of another/example dry/production air passages of an inside of a plastic plate in accordance with this application.

DETAILED DESCRIPTION OF SAMPLE EMBODIMENTS

The numerous innovative teachings of the present application will be described with particular reference to presently preferred embodiments (by way of example, and not of limitation). The present application describes several inventions, and none of the statements below should be taken as limiting the claims generally.
For simplicity and clarity of illustration, the drawing figures illustrate the general manner of construction, and description and details of well-known features and techniques may be omitted to avoid unnecessarily obscuring the invention. Additionally, elements in the drawing figures are not necessarily drawn to scale, some areas or elements may be expanded to help improve understanding of embodiments of the invention.
The terms “first,” “second,” “third,” “fourth,” and the like in the description and the claims, if any, may be used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the terms so used are interchangeable. Furthermore, the terms “comprise,” “include,” “have,” and any variations thereof, are intended to cover non-exclusive inclusions, such that a process, method, article, apparatus, or composition that comprises a list of elements is not necessarily limited to those elements, but may include other elements not expressly listed or inherent to such process, method, article, apparatus, or composition.
The key component of an indirect evaporative cooling system is the indirect evaporative heat exchanger. In reference to FIG. 1, an indirect evaporative heat exchanger 100 includes stack of plastic plates 101 and highly breathable fabric sheets or breathable fill-in materials 103 between the space of plates 101. Plastic plates/sheets 101 are of open celled porous plastic material with sufficient thickness to pass air from side to the other side while the large flat surfaces are sealed and water impermeable. The air passages have thin plastic walls for sufficient heat exchange. Example favored plastic plates includes porous polypropylene sheets/plates sold on Amazon.com.
The example air passage structures of a plastic plate/sheet 101 may be as shown in FIG. 4 where numerous micro open celled holes inside the sealed walls 402 and 404 of plastic sheet comprise continuous open air ways for air to pass from one side 401 to the other side 403. The air passages may also be as shown in FIG. 5 where multiple micro parallel horizontal channels within walls 502 and 504 conduct air from sides 501 and 503. FIG. 4 and FIG. 5 are just two examples, other shapes of air passages are also contemplated and included.
The thickness of the plastic plates/sheets 101 is sufficient to maintain the structural shape of the plates and also sufficiently thin for heat exchange. Favorable thickness is less than 1 cm thick.
Breathable fabric sheets 103 are materials specially coated and woven allowing water vapour through, generally fibers coated with rubber, polyvinyl chloride, polyurethane, silicone elastomer, and/or wax, with special woven patens. If breathability is measured by the rate at which water vapor passes through, in the units of grams of water vapour per square meter of fabric per 24 hour period (g/m2/d), abbreviated to “g”, favorable fabrics tend to have values of 5,000-20,000 g of breathability. Example breathable commercial fabrics include Dupont Coolmax™ polyester, Cordura™ plus nylon, various landscape fabrics, such as Weedblock™ polyester spunbond into swirling web-like sheet for water and air permeability, needle punched-woven fabrics, etc.
Breathable material 103 may be of thin sheets, or no-form, just fill-in fibers, to fill-in the space between two neighboring heat-exchange plates 101. The space between two heat exchange plates 101 is generally less than 0.5 cm, to allow water to flow in and to vapour through.
Evaporative heat exchanger 100 as shown in FIGS. 1 and 2 also includes a water sprayer 109 and rotating spraying bar 107, a water pump 205 in recycling water, and water container 207 in collecting water flow down from the spray on the top. An air blower/pump pumps production input air 111 to go through the heat exchange plates 101, exchange heat with the plates and water sprayed on the plates and come out as cooled production output air 112. Water pump 205 pumps water to water sprayer 109 and 107 which continuously sprays water to plates 101 and the breathable sheets 103. Breathable sheets 103 help distribute water to the plastic heat exchange plates 101 or 203 in FIG. 2 more evenly via capillary force. While water flows down the plates and the breathable sheets by capillary force of the breathable sheets, an air exhauster on the top continuously pulls air 211 up through the space between the heat exchange plates 101 and the breathable sheet 103, facilitating water to evaporate at accelerated rate by absorbing large amount heat from plates 101.
FIG. 2 shows an example of the entry side of the heat exchanger for production air. The multiple air channels of heat exchange plates 203 are open to the entry of the production air while the top and bottom sides are air impermeable. Exhaustion air 211, pumped by air exhauster, flowing vertically goes through the wet passages having water from the water sprayer 201. Water is pumped by water pump 205 through a water tube to water sprayer. Input production air may be first filtered by an air filter 105 as shown in FIG. 1 before going into the heat exchanger. The wet passages formed by the space between plastic heat exchange plates is insulated from the production air, and water is contained inside the wet air channels. The insulation of water inside the wet channels may be achieved by using solid spacers between the heat exchange plates at the injunction between 105.
In reference to FIG. 3, evaporative heat exchanger 100 may be built in units. A single unit may comprise two porous exchanger plates 301 for dry air passages of air 305 and production air 306, and the formed space channel filled with breathable fabric sheet 303 as wet air channel. Wet air 308 passes the wet channel to extract heat from the plates 301. Pluralities of the units may be assembled together for different scales of cooling system. A typical heat exchanger 100 can turn 110 degrees outside air of Las Vegas into 65-70 degree cool air.
The disclosed system may be powered by both solar panels and DC power source, and by batteries for night time. The device may be built by 100% light weight UV-rated high strength plastics, can be easily rolled around a home or business.
The disclosed system may also be suitable for cooling other types of gases or fluids besides air.
As will be recognized by those skilled in the art, the innovative concepts described in the present application can be modified and varied over a tremendous range of applications, and accordingly the scope of patented subject matter is not limited by any of the specific exemplary teachings given. It is intended to embrace all such alternatives, modifications and variations that fall within the spirit and broad scope of the appended claims.
Additional general background, which helps to show variations and implementations, may be found in the cited publications US 2005/0218535 A1 and WO 2010/010576 A1, all of which are hereby incorporated by reference herein for all purposes.
None of the description in the present application should be read as implying that any particular element, step, or function is an essential element which must be included in the claim scope: THE SCOPE OF PATENTED SUBJECT MATTER IS DEFINED ONLY BY THE ALLOWED CLAIMS. Moreover, none of these claims are intended to invoke paragraph six of 35 USC section 112 unless the exact words “means for” are followed by a participle.
The claims as filed are intended to be as comprehensive as possible, and NO subject matter is intentionally relinquished, dedicated, or abandoned.

Claims

What is claimed is:

1. An indirect evaporative cooling device system, comprising:

at least one dry porous-like micro production-air-channel having sufficiently thin and strong walls for heat exchange and air conduction;

at least one wet-air-channel, detachably filled with breathable woven fabrics; and

a water sprayer sufficiently close to said wet-air-channel;

wherein said wet-air-channel and said dry production-air-channel are sufficiently close to each other, evaporation of water from said wet-air channel, with water being sprayed by said water sprayer, causes the walls of production-air-channel to lower temperature, thereby cool the air inside said production-air channel.

2. The indirect evaporative cooling device system of claim 1, wherein said dry production-air-channel is comprised of pores of a porous plastic plate; and said wet-air-channel is formed by spacing of two neighboring plastic plates, sealed from contact with production air.

3. The indirect evaporative cooling device system of claim 2, wherein said porous plastic plate is made of light weight UV-rated polypropylene.

4. The indirect evaporative cooling device system of claim 1, wherein said breathable woven fabrics is a type of commercially available landscaping fabric sheet.

5. The indirect evaporative cooling device system of claim 1, wherein said breathable woven fabrics is a type of commercially available breathable nylon.

6. The indirect evaporative cooling device system of claim 1, wherein said breathable woven fabrics is a type of commercially available breathable polyester.

7. The indirect evaporative cooling device system of claim 1 is powered by solar panels.

8. The indirect evaporative cooling device system of claim 1, further comprising an air exhauster that exhausts humid air from said wet-air channel.

9. An indirect evaporative cooling device system is an assembly of pluralities of the indirect evaporative cooling device system of claim 1.

10. An indirect evaporative cooling device system, comprising:

pluralities of parallel dry porous-like micro production-air-channels having sufficiently thin and strong walls for heat exchange and air conduction;

pluralities of wet-air-channels, detachably filled with breathable woven fabrics, each channel being alternatingly in parallel with at least one of said dry production-air-channels; and

a water sprayer sufficiently close to said pluralities of wet-air-channels;

wherein said wet-air-channels are sufficiently in close contact with at least one of said dry production-air-channels, and evaporation of water from said wet-air channels, with water being sprayed by said water sprayer, causes the walls of production-air-channels to lower temperature, thereby cool the air inside said production-air channels.

11. The indirect evaporative cooling device system of claim 10, wherein a portion of said pluralities of dry production-air-channels are comprised of pores of porous plastic plates.

12. The indirect evaporative cooling device system of claim 10, further having a structure outside frame, wherein the frame is constructed from 100% light weight UV-rated plastics.