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Title:
HYDROPHILIC FILL PACKING FOR COOLING TOWER
Document Type and Number:
WIPO Patent Application WO/2000/075590
Kind Code:
A1
Abstract:
The present invention is an improved fill packing (4) which is hydrophilically treated with ion beam or plasma, and which is used to enhance efficiency of heat exchange in a cooling tower which exhausts heat form a coolant into the atmosphere with direct heat exchange between the coolant and the atmosphere.

Inventors:
Kang, Byung Ha (Hanshin Apt. 60, Chungryangri 1-dong Dongdaemun-ku Seoul 130-011, 106-2002, KR)
Kim, Seo Young (Ssangyong Apt. Chang 4-dong Dobong-ku Seoul 132-044, 107-2301, KR)
Koh, Seok-keun (Hanshin Apt, Chungryangri 1-dong Dongdaemun-ku Seoul 130-011, 101-203 60, KR)
Application Number:
PCT/KR2000/000583
Publication Date:
December 14, 2000
Filing Date:
June 03, 2000
Export Citation:
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Assignee:
KOREA INSTITUTE OF SCIENCE AND TECHNOLOGY (39-1, Hawolgok-dong Seongbuk-ku Seoul 136-791, KR)
Kang, Byung Ha (Hanshin Apt. 60, Chungryangri 1-dong Dongdaemun-ku Seoul 130-011, 106-2002, KR)
Kim, Seo Young (Ssangyong Apt. Chang 4-dong Dobong-ku Seoul 132-044, 107-2301, KR)
Koh, Seok-keun (Hanshin Apt, Chungryangri 1-dong Dongdaemun-ku Seoul 130-011, 101-203 60, KR)
International Classes:
F28F25/00; B01J10/00; F28F25/08; (IPC1-7): F28C1/00
Foreign References:
US3996314A1976-12-07
EP0250061A11987-12-23
Attorney, Agent or Firm:
Chu, Sung-min (Seoul Building, 114-31 Uni-dong Chongro-ku Seoul 110-350, KR)
Download PDF:
Claims:
What is claimed is:
1. A fill packing for a cooling tower which provides heat or mass transfer by directly contacting coolant with air, wherein the surface of the fill packing is hydrophilically treated.
2. The fill packing according to claim 1, wherein said surface of said fill packing is hydrophilically treated by using ion beam.
3. The fill packing according to claim 1, wherein said surface of said fill packing is hydrophilically treated by using plasma.
Description:
HYDROPHILIC FILL PACKING FOR COOLING TOWER BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to fill packing for improving efficiency of heat exchange in a cooling tower and more particularly to a hydrophilic fill packing for a cooling tower which exhausts heat from a coolant into the atmosphere with direct heat exchange between the coolant and the atmosphere.

Description of the Related Art Cooling towers have been widely used in the industry as heat exhausting means for heating equipment and heat source apparatus in addition to equipment for cooling products during manufacturing process, manufacturing machinery and air conditioners. Effective heat exchange in a cooling tower largely affects the performance of an entire system, as a cooling tower is the final equipment which exhausts the heat load from a high temperature heat source, into the atmosphere.

The most common methods for generating air flow can be divided into those used in mechanical cooling towers which use at least one fan for air inflow, atmospheric cooling towers which do not use any mechanical equipment for air flow, and combined cooling towers which use a combination of the above two types of cooling towers. Also, according to the relationship between flows of water and air as coolants, cooling towers may be divided into counterflow cooling towers wherein air flows upwardly in a vertical direction through fill packing while water flows downwardly through the fill packing, and a crossflow cooling tower wherein air flows horizontally across fill packing and water flows downwardly across the fill packing.

Technical developments for the main elements such as a fan, an electric motor, a remover, fill packing and the like, for improving the heat exchange efficiency in a cooling tower, have progressed, and among others, the quality, configuration and arrangement of the fill packing decisively affect the heat exchange efficiency of a cooling tower. The configuration and arrangement of fill packing also affect the distribution of coolant, on which studies have been made.

Although polymer materials for fill packing have good wet-proof and are widely used, coolants form water droplets on the surface of such fill packing due to the

hydrophobicity of the surface of the material, which results in the problem of poor heat exchange efficiency.

SUMMARY OF THE INVENTION It is an object of the present invention to provide fill packing for a cooling tower, whose surface is hydrophilically treated by using ion beam, plasma or the like.

It is another object of the present invention to provide fill packing having durability from reduction of hydrophilicity of its surface and which avoids contaminating a coolant caused by the hydrophilically treated surface of the fill packing as it is washed by the coolant.

These objects are achieved by providing a hydrophilic fill packing for a cooling tower which provides heat or mass transfer, with a coolant contacted directly with air. Specifically, the fill packing of the present invention is adapted for a cooling tower which provides heat or mass transfer by directly contacting coolant with air, wherein the surface of the fill packing is hydrophilically treated.

Preferably, the surface of this fill packing is treated by using ion beam or plasma.

Thus, the surface of the fill packing is hydrophilically treated by using either ion beam or plasma.

BRIEF DESCRIPTION OF THE DRAWINGS Figs. 1 (a) and (b) show schematic views of the structures of mechanical cooling towers.

Figs. 2 (a) and (b) are sectional views showing configurations and distributions of a coolant on the hydrophobic surface and the hydrophilic surface of fill packing, respectively.

Fig. 3 is a graph showing the relationships of the properties of fill packing for cooling towers for a given ratio of water and air, for flow rates of coolants at 3.76 m3/hr/m2 and 4.66 m3/hr/m2, respectively, with inlet temperature of 30 C.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS Fig. 1 shows the general structures of mechanical cooling towers of a counterflow type and a crossflow type. Fig 1 (a) shows a counterflow type cooling tower in which coolant first flows into a coolant inlet 3, where it is cooled with small droplets of injected water by a spay nozzle 8 and supplied on an upper

portion of fill packing 4.

Fig. l (b) shows a crossflow type cooling tower in which a coolant is supplied on an upper portion of fill packing 4 by gravity. Heat or mass in the coolant is transferred to the air introduced from an air inlet 5 while the coolant runs down on the fill packing 4. The coolant cooled by such heat or mass transfer is collected in a water tank 6 at the bottom of the cooling tower and then transported from the cooling tower to the heat source. The air having the increased humidity and temperature is subsequently exhausted to the atmosphere through air outlet 1 by means of fan 2. A cooling tower with fan 2 positioned in the side of the air inlet 5 is referred to as a push blow type, and those with fan 2 positioned on the side of the air outlet 1 is referred to as a suction blow type. Fig. 1 shows a cooling tower of the suction blow type by way of example.

As described above, fill packing 4 plays an important role among the components of the cooling tower as the heat or mass transfer between water as a coolant and the air, are conducted in the fill packing. In the present invention, fill packing whose surface is hydrophilically treated by using ion beam or plasma is used instead of conventional fill packing for improvements to a cooling tower's performance for heat or mass transfer compared with conventional ones. With such fill packing, the performance for all kinds of cooling towers using fill packing such as mechanical and atmospherically controlled cooling towers (or combinations thereof), both counterflow and crossflow cooling towers will all be improved.

Fig. 2 shows distributions of coolants and configurations for their flow in accordance with the degree of hydrophilicity of the respective fill packing surfaces.

Since coolant supplied from the spay nozzle 8, as depicted in Fig. l (a), forms droplets on the fill packing surface which has hydrophobicity, the contact area between the coolant and the air is small, and the flow of the air is clogged, so that the heat exchange efficiency is degraded, and the pressure drop is increased. In contrast, the coolant on the fill packing surface hydrophilically treated spreads widely and runs down, so that the above problems are solved and heat or mass transfer is improved. Furthermore, since improved fluidity of the coolant on the fill packing surface hydrophilically treated prevents formation of scale, clogging therefrom is precluded.

Additionally, when a fill packing's surface is hydrophilically treated, the adhesive property therebetween are improved and construction for the fill packing with adhesives is enhanced. In particular, the fill packing surface may be hydrophilically treated by using the technology disclosed in U. S. Patent No.

5,783,641 and PCT International Application No. PCT/KR98/00372 (which

claims priority from Korean Patent Application No. 1997-61761. With such treatment, the hydrophilicity of the fill packing surface is semi-permanently maintained without damage to the surface despite persistent contact with water.

One embodiment of the hydrophilic fill packing of the present invention is achieved with hydrophilic surface treatment by using ion beam as described in U. S.

Patent No. 5,783,641. First, after the sample whose surface is to be hydrophilically treated is positioned in a vacuum chamber by means of a sample- fixing holder, the vacuum chamber is evacuated under preset vacuum conditions.

Reactive gas is directly introduced around the surface of the sample in the vacuum chamber, and an energized ion beam generated by an ion gun is irradiated on the surface of the sample. At this stage, the sample has a hydrophilic surface by reactive gas and the irradiated ion beam.

Another embodiment of the hydrophilic fill packing of the present invention is achieved by hydrophilic surface treatment using plasma as described in PCT International Application No. PCT/KR98/00372. After an insulated polymeric sample whose surface is to be hydrophilically treated, is positioned at the front of an anode in a vacuum chamber, the vacuum chamber is evacuated to a preset vacuum condition with a vacuum pump. A metal electrode is then used as cathode, and Al or Cu is used as an anode. With predetermined pressure, hydrocarbon gas and reactive gas are introduced into the vacuum chamber. The plasma comprising positive ions, negative ions and radicals of the hydrocarbon and reactive gases are obtained by DC discharge, with the electric power applied to the electrodes. For generation of DC plasma by using such a method, the negative ions from the plasma components move onto the surface of the sample with energy by the effect produced from the anode positioned on the rear of the sample. A functional polymer is polymerized by reaction of such ions and radicals, so that the surface of the polymeric sample is hydrophilically treated.

In order to compare the performance of the heat or mass exchange in two cooling towers which use the hydrophilic fill packing embodied in the present invention and a conventional fill packing, respectively, the characteristic KaV/L values of each fill packing were obtained from separate tests, then compared. A product made of polypropylene employed in a cooling tower of not more than 20RT was employed as conventional fill packing for the cooling tower.

A hydrophilic fill packing whose surface was treated by using ion beam as described above, was used as a fill packing of a cooling tower according to the present invention. Oxygen was used as a reactive gas, and argon was used as gas supplied to a gun. The vacuum chamber was maintained under negative pressure of 1.333 x 10-3 Pa (10-5 torr). Each of the supplied flow amounts of the reactive gas

and the gas supplied to the gun was 6.0 SCCM (standard cubic centimeters per minute). In addition, the fill packing surface was hydrophilically treated by irradiating with ion beam which was achieved by applying electricity at llkV and 0.23 0. 1 liA.

In the experiments, the characteristic KaV/L values of the fill packing were calculated by using the difference in temperatures of the coolant between the inlet and outlet and the differences in humidity and temperature of the air between the inlet and outlet. For KaV/L values, K is a mass transfer coefficient,"a"is the contact area between water and the air per volume of the fill packing, V is the volume of the fill packing, and L is a mass flow rate of a coolant. The experiments were performed with increased revolutions of the fan motor with fixed conditions of the supplied flow amounts of coolant, and at a high temperature for the chamber, Fig. 3 shows the relationships of the characteristics of fill packing for cooling towers for a given ratio of water and air, for volume flow rates of coolants at 3.76 and 4.66 m3/hr/m2, respectively, with inlet temperature of 30 °C. In Fig. 3, KaV/L is as stated above and G is mass flow rate of air. As graphically depicted, Fig. 3 shows that the cooling tower using the hydrophilic fill packing of the present invention has excellent performance increased by at least 15 % of the characteristic value of the fill packing compared with a conventional cooling tower.

The improved performance is due to enhanced heat and mass transfer.

The surface hydrophilically treated with ion beam, plasma or the like has the advantage of semi-permanently maintained hydrophilicity even if it is constantly contacted with water. The hydrophilic fill packing prevents formation of droplets by a coolant and allows easy flow down on the surface. Thus, heat or mass transfer is enhanced because the area of the fill packing surface contacted with the air is maximized. Pressure drop of the air flow (i. e. pressure loss) is reduced, since a coolant does not form droplets and flows smoothly on the fill packing surface. Also, scale due to a coolant is not generated on the fill packing surface hydrophilically treated, so that clogging due to scale is prevented. In addition, manufacture of fill packing is easily achieved due to excellent adhesive properties of the hydrophilic surface. Therefore, the present invention provides a novel addition to cooling towers which employ fill packing by providing one with a surface which is hydrophilically treated by using ion beam, plasma or the like, so that the performance thereof is improved.