Evaporative Chiller Using Plate Type String-Screen-Fills as Heat Exchanger and Fabrication Thereof
The present invention involves an evaporative chiller using a plate type string-screen-fill heat exchanger which is formed of a multiplicity of plate type string-screen-fills with string screens on their both sides. The hot water sprayed on the top perforated plate of the heat exchanger is imbibed into holes on the top plate by surface tension of strings suspending over the holes and then flows down on the surface of strings. During its flowing down on the surface of strings, the water is cooled through evaporation and convection mechanisms of water by contacting with air traveling transversely or slantly through the strings by means of a forced draft. The construction cost and electric consumption saving of the present invention are less than half cost of the current chiller and more than 30%, respectively. The fabrication method of the plate string-screen-fill heat exchanger is described in the present invention.
- U.S. application Ser. No. 13/053,382, Mar. 22, 2011. Park
- U.S. Application No. 61/726,928, Ser. No. 11/21/2012. Park
- U.S. Application No. 61/736,646, Ser. No. 12/13/2012. Park
- U.S. application Ser. No. 13/888,327, Jun. 6, 2013. Park
- KR 100393126 Jul. 18, 2003 Park
- KR 100516391 Sep. 14, 2005 Park
- KR 100516392 Sep. 14, 2005 Park
- PCT WO 2005/008159 A1 Jan. 27, 2005 Park
- Telstar International Technology Co., Ltd., http://www.telstar-tech.com.tw/Product/fan-04.htm
- Cooling Tower Depot, Cross Flow Fill With Louver or Drift Eliminator,
- http://www.streamlineextrusion.com/files/manuals/paper4.pdf.
- STAR COOLING TOWERS, Counterflow and Crossflow Film Fills,
- http://starcoolingtowers.com/coolingtowerfill
- Wikipedia, http://en.wikipedia.org/wiki/Wind_chill
Not Applicable.
REFERENCE TO SEQUENCE LISTING, A TABLE, OR A COMPUTER PROGRAM LISTING CPMPACT DISC APPENDIXNot Applicable.
BACKGROUND OF THE INVENTION1. Field of the Invention
The present invention relates to chiller utilizing evaporative cooling fill medium heat exchanger. More precisely, the present invention relates to an evaporative chiller using plate type string screen fills as a heat exchanger, which is fabricated with strings, using the unique characteristics of string: flowing down of water on the surface of the vertical string by gravity force, surface tension of string strong enough to hold the water on the surface of string against the strength of cooling air draughts, and capability of contacting water and cooling air with barely resisting air flowing through the strings.
2. Description of the Related Art
Cooling of warm water by contacting with ambient air is accomplished mainly through evaporation of water molecules and convection of heat. The evaporation of water molecules needs latent heat plus specific heat of water. Absorbing the evaporation heat from the warm water, the water molecules are vaporized to become vapor and in turn the warm water loses its preserved heat by that much heat transferred to the air. If air is not moving around the surface of warm water, the vapor molecules accumulates to saturate and then the effective evaporation is terminated. The convection of heat is to transfer heat from warm water to cooler air, which means the warm water dissipates its heat to the cooler air around the surface of warm water. Then, the warm water loses its heat and reversely the cooler air around the surface of warm water gets warmer. The warm air forms an insulating boundary layer around the surface of warm water. The warm air insulation layer resists a transfer of heat from warm water to air to terminate the transfer of heat from warm water to air. If air is moving around the surface of warm water, the moving air disrupts both of the saturated vapor and the boundary layer of the warm air, allowing for new dry and cooler air to replace the humid and warm air around the surface of warm water to continuously cool the warm water. Therefore, the rate of heat loss on the surface of warm water through evaporation and convection depends on the blowing speed of air on the surface of warm water. Such an effect of cooling speed is a wind chill whose effect is to quickly reduce the warm water cooler than the ambient temperature, but it cannot reduce ultimately the temperature of warm water below the ambient temperature. See reference of http://en.wikipedia.org/wiki/Wind_chill for more information on cooling effects of moving air. To use such cooling mechanism of warm water by contacting cool air and warm water, PVC film fills are adapted in current cooling towers.
Currently, a chiller or cooling tower is employed to cool warm water to prevent industrial hot temperature equipment, like metal melting crucible, extruder, hot sintering furnace, etc., as well as a building air conditioning system, from breaking down by heat overload. The chiller consists of compressor, heat exchanger (condenser), water tank cooing hot water, water circulation pump for cooling heat generator, and cooling tower or air cooling fan. The chiller cools hot water by contacting with low temperature refrigerant flowing in coolant pipes which locate in the water tank. The low temperature refrigerant is provided by the operation of compressor. The operation of compressor requires a large amount of electricity. Therefore, the larger the chiller is, the more consumption of electricity cannot be avoided. Such a mode of operation of chiller is one of disadvantages of the current chiller. Another disadvantage is that the operational loop of the compressor includes compressor, condenser, cooling tower or cooling fan, expansion valve, and cooling chemical agent. Such fabrication requiring several components increases fabrication cost of the current chiller. And the further disadvantage is that the current chiller is not environmentally friendly due to a usage of the cooling chemical agent which is one of environmental pollutants. The cooling towers are categorized into open and closed loop cooling tower. The closed loop cooling tower cools the heat generator by passing the cooled water through the surface of heat generator or by indirectly cooling a buffer water tank cooling the heat generator by passing the cooled water through the water circulation loop pipe in the buffer water tank. Such operation of the closed cooling tower cannot avoid an insufficient cooling effect due to indirect contact of cooled and warm water, which limits application of the closed loop cooling tower. The open loop cooling tower cannot be applied to the cooling of the heat generator due to accumulation of particles in the cooling surface area of the heat generator and in the cooling water loop because of particles contaminated into the water through cooling tower from environmental atmosphere. Another minor disadvantage of the open and closed loop cooling tower is the ice spike of water pipe in winter. To prevent the ice spike of the water pipe, a careful maintenance of the cooling tower is necessary and for the operation of heat generator in winter, other cooling system should be used.
To compensate such disadvantages of the current chiller and cooling tower, the evaporative chiller was recently invented and patented by the inventor of the present invention, such as described in Korean Patent 100393126, 100516391, 100516392, and PCT/KR3004/001825. The evaporative chiller is schematically drawn in
The water cooling functions and advantages of the rectangular string fills pack previously invented by the present inventor are briefly described in this section. When the water to be cooled is sprayed on the top perforated plate of the rectangular string fills pack, the sprayed water spreads over the top perforated plate and is imbibed down through the holes by the surface tension of strings suspending from and through the holes on the top and bottom plates of the string fills pack, then flowing down on the surface of strings. The water flowing down on the surface of strings becomes circumferential thin film water on the circular surface of string, which can make a contacting area between water and cooling air maximized and also make the water as thin as possible. Such conditions of the water flowing down on the surface of strings are significant advantages of strings to provide high water cooling efficiency of water. And another significant advantage of string is that the flowing down of water on the surface of strings do not create any conditions of forming scales and fouling on strings, which means no formation of the scales and fouling in string fills pack, resulting in no-reduction of the flowing rate of cooling air and the serve life of string fills pack.
The purpose of the present invention is a fabrication of the evaporative chiller using the innovative plate type string-screen-fills being free of the disadvantages exhibited in the large string fill media evaporative chillers, requiring a much less fabrication efforts and far lower fabrication cost.
SUMMARY OF THE INVENTIONTo eliminate the disadvantages of chiller currently in use and large string evaporative heat exchanger described above and to improve the fabrication of the evaporative chiller, the Plate Type String-Screen-Fills (SSFs) invented by the present inventor, applying to U.S. patent (U.S. application Ser. No. 13/053,382), are applied and proved to be adequate for their application to the evaporative chiller, since they have several advantages given as follows.
- 1. They can be simply fabricated without great efforts.
- 2. They have a high water cooling efficiency.
- 3. They are not attacked by any water chemicals because they are made of inert materials like polyester, high density polyethylene, and aluminum (any other materials are possible).
- 4. They deploy a large surface area in a relatively small volume, thereby maximizing heat transfer.
- 5. They can operate at high water temperature in excess of 57° C. (135° F.) without loss of their physical integrity or mechanical strength.
- 6. Their materials are non-toxic, non-hazardous, and suitable for easy and safe disposal at the end of service life.
The fabrication of the evaporative chiller is completed through four steps of fabrications: determination of fabrication factors, the fabrication of SSFs and SSF packs, installation of the SSF packs into the evaporative chiller, and performance test of the evaporative chiller. The determination of fabrication factors of SSF and SSF pack requires determination of a lot of factors such as string materials and type, hole size on the top and bottom perforated plate of the evaporative heat exchanger, interval between adjacent strings in the heat exchanger, specific number of strings per unit cross section area of SSF pack, variation of specific area of SSF pack depending on string diameter, water cooling effective length of string in the heat exchanger, verification of flying away of water from strings, slanting angle of string slantly installed in the heat exchanger, correlation factor for computation of hole size from arbitrary string size, and cooling effect due to string type. The fabrication of SSFs and SSFs packs includes fabrication of SSF frame including attachment tabs and semi-circular holes on frame, winding string over the SSF frame, and assembly of plurality of SSFs into SSF pack. One or more SSF packs are installed into the location of the heat exchanger in the evaporative chiller and then finally the performance of the evaporative chiller is tested. The determination of fabrication factors of the SSF and SSF pack and the fabrication of SSF and SSF pack are described in detail in the previous invention of String-Thick-Plates (STP) Pack for Use in Cooling Tower (U.S. application Ser. No. 13/053,382) invented by the present inventor. The installation of SSF packs in the evaporative chiller and its performance test are described here in the present invention and also the fabrication of the SSF and SSF pack is briefly described.
<Evaporative Chiller of Present Invention> The SSF evaporative chiller of the present invention provides two distinct vital functions: (1) cooling of hot water, flowing down on the surface of strings suspending from the top and bottom perforated plate of SSF heat exchanger, by evaporation and convection mechanism of water contacting with air transversely traveling through the strings after entering the SSF heat exchanger passing the air filter on the air entrance of evaporative chiller and (2) eliminating of vapor, generated through cooling process of hot water in the SSF heat exchanger, by condensing and absorbing vapor on the cold water flowing down on the surfaces of strings vertically and slantly suspending from the top and bottom of the vapor absorber in the cross current evaporative chiller (CrCEC) and counter current evaporative chiller (CoCEC), respectively. Such evaporative chillers are fabricated as in the same configurations as the SSF media cooling towers are fabricated, so that they are categorized as cross current and counter current evaporative chillers.
The CrCEC of the present invention are fabricated in several configurations to meet required demands of fabrication. Their configurations are determined due to the arrangement of SSF pack heat exchanger in the CrCEC and their key components are SSF pack heat exchanger, vapor absorber, water circulation pump, and vacuum exhaust fan blower. A basic standard CrCEC of the present invention is schematically illustrated as shown in
Basic standard CoCEC of the present invention are schematically illustrated as shown in
The SSF evaporative chiller is installed inside or outside building. The SSF evaporative chiller to be installed inside building requires a vapor exhaust duct connected outside building from the chiller and sirocco fan blower which strongly sucks and discharges air (see reference of Telstar International Technology Co., Ltd.), while the vapor exhaust duct is not necessary and the ventilation fan blower is preferred when the SSF evaporative chiller is installed outside building. When the SSF evaporative chiller is installed outside building, the ventilation fan blower is attached on the top or side wall of the chiller with automatic louver damper at the outside of fan to prevent coming-into of dusts. To blow out the vapor through the vapor exhaust duct, the sirocco fan blower is indispensable, because it has a strong suction and discharging of air through the duct. Hence, the sirocco fan blower is attached on the top or side wall of the chiller inside building as shown in
<Fabrication of SSF and SSF Pack> Fabrication of the SSF and SSF pack invented by the present inventor is briefly described as follows. The SSF pack is schematically shown in
The SSF pack is fabricated by assembling a plurality of SSFs invented by the inventor of the present invention. One unit of SSF is a rectangular shaped string screen plate with two vertical-string-screens (VSSs) on its both sides, which are apart in 1 cm, other dimensions are possible, and strings are wound over the top and bottom frames in the longitudinal direction as shown in FIGS. 6A and 6B. The VSS is comprised of several strings vertically suspended from the top and bottom frames separated sufficiently apart from each other as shown in
The SSFs are fabricated by winding a single long string over the top and bottom frames of rectangular frames of the SSFs and then as shown in
<Fabrication of Vapor Absorber> Using a condensing of water vapor on cold materials (lower temperature than a dew point of water vapor), the vapor absorber is fabricated to condense the water vapor on cold water flowing down on the surface of strings. The fabrication method of the vapor absorber is exactly same with that of the SSF pack heat exchanger. However, the vapor absorber is small and the spacing of strings loaded in the vapor absorber is much shorter than in the heat exchanger and therefore the specific surface area of the strings of 2.5 mm in diameter is increased by 4 times, which is 60 ft2/ft3 compared with 15 ft2/ft3 of the SSF pack heat exchanger. The cold water is supplied from tap water whose temperature is in the range of 50 to 68° F. in Summer and 40 to 55° F. in Spring and Fall. Hence, since the temperature and humidity of the vapor in the SSF evaporative chiller is around 75 to 85° F. and higher than 85%, respectively, the dew point of the 85% vapor is in the range of 70 to 79° F. Then, the tap water temperature, 50 to 68° F., is lower than the dew point of the vapor generated in the SSF evaporative chiller. Therefore, most vapor generated by the SSF evaporative chiller in all seasons is removed from the exhaust air stream by the vapor absorber. As a result of removal of vapor from the exhaust air stream, a white smoke exhausted from the duct of SSF evaporative chiller produced due to exhausting of vapor is not shown up. The vapor absorber is designed for the tap water to be supplied to the top of vapor absorber by the rate of a half gallon per min per square feet (other rate is possible) of the top surface of vapor absorber and to be added to main stream of circulation water after passing through the vapor absorber. The vapor absorber is fabricated in a rectangular shape for CrCEC as shown in
<Advantages of Present Invention> One of major advantages of the present invention is the ability to substantially reduce the electric consumption of current chiller by more than 30% because the present invention does not use compressor. The larger cooling capacity of the evaporative chiller, the smaller amount of electric consumption can be expected.
Another major advantage of the present invention is the ability to fabricate the evaporative chiller in several shapes other than rectangular like square, pentagon, and hexagon, whose wall surfaces are used as the entrance of cooling air, providing high cooling efficiencies.
Yet another major advantage of the present invention is the ability to fabricate the evaporative chillers with any of the square, pentagon, and hexagonal cross current evaporative heat exchanger, but hexagon is preferred to other shapes, to provide the best operating conditions such as usage of smaller space due to smaller size and less restriction of construction place.
Another major advantage of the present invention is the ability to easily fabricatd and install the SSF packs without spending great efforts by press joining attachment and piling tabs on the frames of SSFs and easy carrying the SSF packs because of their light weights.
Minor advantage of the present invention is the ability to eliminate the production of a white smoke which is usually exhausted from cooling towers.
Minor advantage of the present invention is the ability to be in service life of more than 25 years since the polyester strings and aluminum used in the present invention has excellent physical and chemical properties like high melting temperature, high resistance to most chemicals, high tenacity for stretching and shrinking, and high durability.
And further advantage of the SSF packs of the present invention within the cooling towers is that the materials of the SSF pack, polyester strings, aluminum or aluminum alloy, polypropylene, are non-hazardous and suitable for safe and disposal at the end of service life.
<Description of Number in the Drawings> 1 standard SSF evaporative chiller, 2 rectangular CrC-SSF heat exchanger, 3 hot water sprayer, 4 top perforated plate of rectangular CrC-SSF heat exchanger, 5 bottom perforated plate of rectangular CrC-SSF heat exchanger, 6 air filter, 7 air stream and its flow direction, 8 cold water reservoir, 9 tap water solenoid valve, 10 tap water inlet port, 11 tap water supplying pipe to vapor absorber, 12 water inlet pipe to water circulation pump, 13 water circulation pump, 14 hot water inlet port, 15 cold water outlet port, 16 water flow meter/thermometer, 17 water flow meter/water filter/thermometer, 18 rectangular shape vapor absorber, 19 fan blower, 20 hot water inlet pipe to SSF heat exchanger, 21 SSF pack to be installed in cross current evaporative chiller or CrC-SSF pack, 22 SSF (simple notation of CrC-SSF, single unit of SSF), 23 string, 24 top perforated plate distributing water into the SSFs pack; 25 bottom perforated plate passing water out of the SSFs pack, 26 string loaded hole passing water through hole, 27 guiding wall to control direction of traveling of cooling air, 28 pathway of cooling air, 29 rectangular cross current evaporative chiller, 30 rectangular assembly of CrC-SSF packs, 31 square cross current evaporative chiller, 32 trapezoidal assembly of CrC-SSF packs, 33 pentagonal cross current evaporative chiller, 34 hexagonal cross current evaporative chiller, 35 V-type counter current evaporative chiller, 36 V-type SSF heat exchanger, fill media of CoC-SSF packs installed in V-type SSF heat exchanger in counter current evaporative chiller, 37 hot water distributer, 38 cooling air entrance of counter current evaporative chiller, 39 traveling direction of cooling air in counter current evaporative chiller, 40 V-type vapor absorber, 41 tap water supplying pipe to V-type vapor absorber, 42 tap water sprayer of vapor absorber, 43 vapor absorbed tap water returning pipe to cold water reservoir, 44 top perforated plate of V-type CoC-SSF pack, 45 X-type counter current evaporative chiller, 46 slanted rectangular CoC-SSF pack, 47 slanted CoC-SSF, 48 top perforated plate of slanted rectangular CoC-SSF pack, 49 V-type CoC-SSF pack, 50 side frame of slanted CoC-SSF, 51 bottom frame of slanted CoC-SSF, 52 top frame of slanted CoC-SSF, 53 sirocco fan blower, 54 image line of duct, 55 air traveling direction through sirocco fan blower, 56 SSF evaporative exchanger equipped with multi-SSF heat exchangers, 57 attachment line to SSF evaporative chiller; 58 top frame of CrC-SSF frame, 59 side frame of CrC-SSF frame, 60 bottom frame of CrC-SSF frame, 61 current commercial wet chiller, 62 primary coolant loop, 63 hot water pipe, 64 heat generator, 65 cold water pipe, 66 primary coolant water circulation pump, 67 water tank heat exchanger, 68 tap water supplying port, 69 water supplying controller, 70 secondary gas coolant loop, 71 cold coolant gas line, 72 gas expansion valve, 73 condenser, 74 hot coolant gas line, 75 compressor, 76 tertiary coolant water line, 77 warm water line, 78 cooling tower water circulation pump, 79 cooling tower, 80 dot line indicating primary coolant loop, 81 current commercial dry chiller, 82 air cooling fan, 83 air cooling condenser.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT<Fabrication of Evaporative Chiller> The evaporative chiller 1 is fabricated by employing 10 components such as SSF heat exchanger 2, vapor absorber 18, 40, vacuum exhaust fan blower 19, water circulation pump 13, solenoid valve 8, air filter 6, water filters 17, water flowmeter 16, 17, water thermometer 16, 17, and water sprayer 3. Among them, the key components, SSF heat exchanger 2, vapor absorber 18, 40, and vacuum exhaust fan blower 19, are horizontally installed in the CrCEC 29, 31, 32, 34 and vertically installed in the CoCEC 36 in their sequence order, and the water circulation pumps 13 in both evaporative chillers are installed on the floor of chiller as shown in
<Installation of SSF Packs in Evaporative Chiller> Installation method of the SSF packs 21 of the present invention is exactly same as installed in the evaporative chiller with one unit large evaporative heat exchanger 2 (KR 100494126) invented by the present inventor for CrCEC 2, 29, 31, 33, and 34, but quite different for CoCEC 35, 45.
However, the cross current (CrC)-SSF packs 30 are employed in any shape of CrCECs 29, 31, 33, 34. The typical shapes of CrCECs in which the CrC-SSF packs 21 can be installed are rectangle 29, square 31, regular pentagon 33, and regular hexagon 34 (other shapes are possible) as shown in
<Operation of SSF Evaporative Chiller> Operation of the SSF evaporative chiller is described using the basic standard CrCEC 1 shown in
The hot water supplied to the top of the SSF heat exchanger 2 is sprayed on the top perforated plate 4 through the water sprayer 3. The hot water sprayed on the perforated plate 4, 24 imbibes into the holes 25 on the perforated plate 4, 24 by surface tension of strings 23 suspended over the holes 25 and then flows down on the surfaces of the strings 23 to flow into the water reservoir tank 8. During flowing down the strings 23, the hot water is cooled. The cooled water is collected in the water reservoir tank 8 and the collected cooled water is recirculated through the coolant loop 62 to cool the heat generator 64. Right after starting the operation of water circulation pump 8, the operating of fan blower 19 at the rear of SSF evaporative chiller 1 starts, and then the cooling air 7 is sucked in to enter the SSF evaporative chiller 1 from indoor environment through the air filter 6 at the air entrance of SSF heat exchanger 2. The cooling air travels transversely through the strings 23 vertically suspending from top and bottom perforated plates 4, 5 of the SSF heat exchanger 2 and cools the hot water flowing down on the surface of strings 23 by contacting the hot water on the surfaces of strings 23 and blowing vapor away from the strings 23 into cooling air stream 7. The high humid air passing through the SSF heat exchanger 2 continues to enter the vapor absorber 18 and travel perpendicularly to the streams of cold tap water flowing down on the strings 23 vertically suspended in the vapor absorber 18. During passing through the vapor absorber 18, the vapor in the air stream is condensed by contacting with the cold tap water and absorbed in the tap water stream, which flows into the water reservoir tank 8 and is added to the heat generator coolant water. Some amount of vapor remains in the air stream 7 and is discharged into the environment through the fan blower 19.
<Comparison of Operation Loops of SSF Evaporative Chiller with Current Chillers> Current operating commercial chillers are categorized into wet and dry chillers 61, 81 according to condenser 73 cooling method. The schematic pictures of operation loops of the wet and dry chillers 61, 81 are shown in
From the
While the present invention has been described as having an exemplary design, this invention may be further modified within the concept and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention relates.
Claims
1. An evaporative chiller using string-screen-fill pack, comprising:
- a multiplicity of string-screen-fills each having a pair of vertical-string-screens on both sides of said string-screen-fill, each of said vertical-string-screen having vertical strings separated sufficiently apart from each other, wherein said vertical strings passing through and over semi-circular holes on the frame of said string-screen-fill;
- several of attachment tabs on said string-screen-fill frame, each of said attachment tabs locating on said string-screen-fill frame for joining said string-screen-fills, whereby said attachment tabs are joined by aligning said attachment tabs with and inserting into the counterpart tabs of said string-screen-fill to be joined by pressing.
2. A string-screen-fill pack for use in evaporative chiller as recited in claim 1, wherein said string-screen-fill packs are employed in rectangular, square, pentagon, and hexagon cooling towers, wherein said rectangular cooling tower has two fill zones of said string-screen-fill packs near to two entrances of cooling air, wherein said square cooling tower may have said string-screen-fill packs to be placed near to two side or four side wall entrance of cooling air, and wherein said string-screen-fill packs are placed near to the entrances of cooling air at the entire outside walls of said pentagon and hexagon evaporative chillers.
3. A string-screen-fill pack for use in evaporative chillers as recited in claim 1, wherein said string-screen-fill packs are employed in counter current evaporative chiller, and wherein said slanted string-screen-fill packs are installed in shape of V-type or X-type fill media.
Type: Application
Filed: Nov 4, 2013
Publication Date: Nov 20, 2014
Inventor: Chong Mook Park (Falls Church, VA)
Application Number: 14/071,104
International Classification: F25B 39/02 (20060101);