CN102492322A - Nano-coating for unsaturated evaporation heat transfer surface - Google Patents
Nano-coating for unsaturated evaporation heat transfer surface Download PDFInfo
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- CN102492322A CN102492322A CN2011104074829A CN201110407482A CN102492322A CN 102492322 A CN102492322 A CN 102492322A CN 2011104074829 A CN2011104074829 A CN 2011104074829A CN 201110407482 A CN201110407482 A CN 201110407482A CN 102492322 A CN102492322 A CN 102492322A
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Abstract
The invention discloses a nano-coating for an unsaturated evaporation heat transfer surface. An anti-corrosion layer and a hydrophilic layer can be coated on the heat transfer surface in sequence; a heat transfer layer can be coated between the anti-corrosion layer and the hydrophilic layer; the coated heat transfer surface is irradiated with ultraviolet light for one hour, so that a contact angle between a coated surface and a water film is reduced to 0-5 degrees; the coating thickness of the anti-corrosive layer is 2-15 nanometers; the coating thickness of the hydrophilic layer is 8-35 nanometers; and ultraviolet light is used for irradiating intermittently every 2-3 days, so that the hydrophilicity of the coated surface is kept. The material characteristic of a heat exchange surface is improved, so that a spreading area on the heat transfer surface under the unit water amount of the water film is increased, distribution is more uniform, the phenomenon of 'dry spot' is avoided effectively, the scaling phenomenon of the heat transfer surface is delayed, heat and mass transfer coefficients between water and air are increased, and heat exchange performance is enhanced.
Description
Technical field
The present invention relates to a kind of nano coating that is used for unsaturation evaporation heat transfer surface, belong to the intensifying heat transfer technical field.
Background technology
Along with becoming increasingly conspicuous of the energy and environmental problem, the energy-saving and water-saving problem causes common concern, and evaporative condenser has obtained using widely in China as a kind of efficient energy-saving water-saving heat-exchange equipment.
In the evaporative condenser working process, heat exchange surface unsaturation evaporation relates to the heat and mass of air-water two, in the condensation of refrigerant exothermic process; Cooling circulating water through water distributor after nozzle spray in heat transfer tube surface; Form water membrane at tube-surface, air is blown into from the tube bank bottom, with the moisture film caloic exchange of tube-surface; Formation unsaturation evaporation, wherein mobile the and distribution character of moisture film on heat exchange surface has material impact to its heat exchange property.The unsaturation evaporation mainly occurs on the contact interface of heat-transfer pipe wall surface moisture film and air, and this process is discontinuous falling liquid film process, and moisture film is difficult to cover equably tube-surface, therefore can not reach maximum unsaturation evaporation; In the place that moisture film can not cover, because the existence of evaporation is easy to form " dry spot " phenomenon, of long duration not only form dirty body and reduce heat exchange efficiency greatly, and can cause corrosion failure tube wall.
Summary of the invention
To the deficiency of prior art, the present invention provides a kind of unsaturation evaporation heat transfer nano surface coating, is intended to delay the scale formation of heating surface through improving the material behavior of heat exchange surface, strengthens the caloic fraction exchange of water and air, has improved heat exchange property
The present invention adopts following technical scheme:
A kind of nano coating that is used for unsaturation evaporation heat transfer surface comprises and covers preservative coat and hydrophilic layer that it is characterized in that, described nano coating prepares through following method:
1) prepare the coating working solution: the aqueous phosphate solution that with the volumetric molar concentration is 1.2mol/kg is as the preservative coat working solution; Again with butyl(tetra)titanate, absolute ethyl alcohol and methyl ethyl diketone, Silver Nitrate, deionized water with 1.0: 30: 1.0: after 0.05: 2.0 volumetric molar concentration is configured to solution; Stirred 15 minutes; With pH value to 5～6 of nitric acid regulator solution, again that this solution stirring is even, obtain the hydrophilic layer working solution;
2) coating applies: adopt the working solution of step 1) preparation, anticorrosive coating and hydrophilic layer successively on heat exchange surface; Heat exchange surface 1h after filming with UV-irradiation again makes the contact angle of film coated surface and moisture film be reduced to 0 °～5 °, and wherein the coating thickness of preservative coat is 2-15nm, and the coating thickness of hydrophilic layer is 8-35nm; The UV-light intermittent irradiation is adopted at every interval 2～3 days, keeps the wetting ability of film coated surface.
In technique scheme, described nano coating is preferably and between preservative coat and hydrophilic layer, applies a heat transfer layer, and the working solution of described heat transfer layer is the fused solution that contains metallic zinc, and coating thickness is 2-10nm.
In technique scheme, a kind of in sol-gel method, pickling process, spraying method, chemical Vapor deposition process and the magnetron sputtering method adopted in the coating of described nano coating.
The present invention is at heating surface anticorrosive coating successively and hydrophilic layer, and for the enhance heat transfer effect, the present invention can also apply heat transfer layer between preservative coat and hydrophilic layer.After apply accomplishing, the heat exchange surface 1h after filming with UV-irradiation causes TiO
2The film surface structure changes, and inspires very strong wetting ability, makes nano-TiO
2The contact angle of film coated surface and moisture film is reduced to below 5 °, even can reach 0 °.After stopping rayed, Superhydrophilic still can keep 2～3 days, slowly returned to the preceding hydrophobic state of rayed then.After adding the uv ray irradiation again, recover Superhydrophilic again.Adopt the UV-light intermittent irradiation, just can make the surface have ultra water-wet behavior all the time.
Described preservative coat can adopt general nano anti-corrosive material, sodium phosphate for example, and the method for coating can adopt existing method in common, and the thickness of coating is 2-15nm; Described hydrophilic layer adopts the nano-TiO of doping Ag
2, the thickness of coating is 8-35nm; Increasing between preservative coat and the hydrophilic layer under the situation of heat transfer layer, heat-transfer effect was best when said heat transfer layer thickness was 2-10nm, and heat transfer layer can adopt general heat-transfer matcrial, for example contains the fused solution of metallic zinc.The coating method of all coatings can be existing method in common, for example sol-gel method, pickling process, spraying method, chemical Vapor deposition process and magnetron sputtering method etc.
Compared with prior art, the invention has the beneficial effects as follows:
(1) existence of hydrophilic layer; Increased moisture film heat exchanging wetting of surfaces performance; The contraction that the moisture film that suppresses to be heated causes owing to the surface tension difference in the decline evaporative process on heat transfer sheet improves the fraction of coverage of moisture film, the caloic transmission area between increase wall-moisture film-air three;
(2) it is poor to have reduced solid-liquid interfacial tension, has increased spreading area and the renewal speed of moisture film on heat exchange surface, has reduced water film thickness, and then has increased the film heat transfer coefficient of water film surface;
(3) can make moisture film at the contact angle of heat exchange surface less than 5 °, thereby make spray water can effectively encase all surface of heat transfer tube, eliminate " dry spot " phenomenon, make water, air and intraductal working medium carry out effectively sufficient heat exchange;
(4) contain preservative coat in the nano-hydrophilic coating, eliminate and slowed down the corrosion of water, improved work-ing life tubing;
(5) contain heat transfer layer in the nano-hydrophilic coating, can improve the heat conductivility of tubing, heat transfer coefficient is able to increase, thereby improves heat-transfer effect;
(6) under equal heat interchanging area and identical operations condition, nano-hydrophilic coating heat transfer tube can improve heat exchange efficiency 15～30%.
Description of drawings
Fig. 1 plate evaporation formula condensing surface contour structures synoptic diagram
Wherein: 1-heat exchanger plates pipe, 2-water distribution system, 3-aerofoil fan, 4-shelves water plate, 5-housing, 6-circulating water line, 7-water circulating pump, 8-water collecting basin, 9-air-inlet grille
Fig. 2 is the structural representation of the heat exchanger plates pipe group among Fig. 1
Fig. 3 is the A-A sectional view of single heat exchanger plates pipe among Fig. 2
Wherein: 1-heat exchanger plates pipe, 1-1 preservative coat, 1-2 heat transfer layer, 1-3 hydrophilic layer
Embodiment
For understanding the present invention better, below in conjunction with accompanying drawing and embodiment the present invention is done further description, but the embodiment of part is not limit so.
As shown in Figure 1, be the contour structures of plate evaporation formula condensing surface, the plate bundle of mainly forming by heat exchanger plates pipe 1, top water collector 2, aerofoil fan 3, water eliminator 4, housing 5, circulating water line 6, water pump 7, water leg 8, air intake grid 9 constitutes.The heat exchanger plates pipe is installed between top water collector 6 and the air-inlet grille 9, walks condensing agent in the pipe, the outer airflow that spray water and forced-flow are arranged of pipe, and tube-surface covers water membrane, forms the unsaturation evaporation.
As shown in Figure 2, be the heat exchanger plates pipe, cast is a waved plate, plate The selection of pipe stainless steel.After two layers of the needs apolegamys or three-decker according to reality, apolegamy nano-hydrophilic coating solution.Zinc adds in the nano-hydrophilic coating can have improved corrosion resistant coating in the generation of parent tube surface; Parent tube has zinc-plated provide protection simultaneously; The thermal conductivity of zinc is big than some metal such as carbon steel, and is far longer than the thermal conductivity of organic substance, has strengthened heat transfer to a certain extent.
Before the applying coating, at first preferably add the acidity or the alkalis of some metal-salt or metal acid-salt and handle the heat exchanger plates pipe, then adopt chromic acid chromic salts, Plessy's green hydrochlorate or chromium-free treatment machine to carry out antirust processing.At last, adopt sol-gel method, pickling process, spraying method and chemical Vapor deposition process or magnetron sputtering method, exchange hot plate tube-surface carries out the processing of nano-hydrophilic property.Select for use the Prepared by Sol Gel Method coating to have the purity height, simple to operate and reaction conditions is easy to advantages such as control.After the hydrophilic treatment, be cooled to room temperature, can obtain the heat exchanger plates pipe of surface-coated nano-hydrophilic coating,, excite the Superhydrophilic of coating at ultra violet lamp coating 1h at 400～500 ℃ of temperature lower calcination 10～60min.
Embodiment 1
The preparation hydrophilic layer: with butyl(tetra)titanate, absolute ethyl alcohol and methyl ethyl diketone, Silver Nitrate, deionized water with 1.0: 30: 1.0: after 0.05: 2.0 volumetric molar concentration is configured to solution, stirred 15 minutes, with pH value to 5～6 of nitric acid regulator solution, restir is even; It is the sodium radio-phosphate,P-32 solution of 1.2mol/kg that preservative coat is selected concentration for use; Heat transfer layer is selected the fused solution that contains metallic zinc for use;
Adopt stainless steel ripple heat exchanger plates pipe, apply and obtain coating structure shown in Figure 3, wherein the thickness of hydrophilic layer 1-3nm gets 8,15 and 35nm respectively, and the thickness of preservative coat 1-1 gets 2,10 and 15nm respectively, and the thickness of heat transfer layer 1-2 gets 2,5 and 10nm respectively.The total thickness of the three-decker coating that obtains is 12,30 and 60nm.Selecting wavelength for use is that 365nm, power are the ultra violet lamp coating 1h of 10W.
Experiment shows, has adopted unsaturation evaporation heat transfer nano surface hydrophilic coating to handle heat exchanger plates pipe later, and the contact angle of surface hydrophilic film is reduced to 4 °, 2 ° and 3 ° respectively by 42 °, 36 ° and 39 ° of original heat exchanger plates pipe.The heat exchanger plates pipe that evaporative condenser adopts this routine coating to handle, water saving is respectively 18%, 30% and 27%, and heat transfer property raising relatively is respectively 23%, 35% and 27%.
Claims (3)
1. a nano coating that is used for unsaturation evaporation heat transfer surface comprises and covers preservative coat and hydrophilic layer, it is characterized in that, described nano coating is preparation like this:
1) prepare the coating working solution: the aqueous phosphate solution that with the volumetric molar concentration is 1.2mol/kg is as the preservative coat working solution; Again with butyl(tetra)titanate, absolute ethyl alcohol and methyl ethyl diketone, Silver Nitrate, deionized water with 1.0: 30: 1.0: after 0.05: 2.0 volumetric molar concentration is configured to solution; Stirred 15 minutes; With pH value to 5～6 of nitric acid regulator solution, continue down to stir 12 hours in 60 ℃, obtain the hydrophilic layer working solution;
2) coating applies: adopt the working solution of step 1) preparation, anticorrosive coating and hydrophilic layer successively on heat exchange surface; Heat exchange surface 1h after filming with UV-irradiation again makes the contact angle of film coated surface and moisture film be reduced to 0 °～5 °, and wherein the coating thickness of preservative coat is 2-15nm, and the coating thickness of hydrophilic layer is 8-35nm; The UV-light intermittent irradiation is adopted at every interval 2～3 days, keeps the wetting ability of film coated surface.
2. the nano coating that is used for unsaturation evaporation heat transfer surface as claimed in claim 1; It is characterized in that; Described nano coating is preparation like this: between described preservative coat and hydrophilic layer, apply a heat transfer layer; The working solution of heat transfer layer is the fused solution that contains metallic zinc, and coating thickness is 2-10nm.
3. the nano coating that is used for unsaturation evaporation heat transfer surface as claimed in claim 1 is characterized in that, a kind of in sol-gel method, pickling process, spraying method, chemical Vapor deposition process and the magnetron sputtering method adopted in the coating of described nano coating.
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| Application Number | Priority Date | Filing Date | Title |
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| CN2011104074829A CN102492322A (en) | 2011-12-09 | 2011-12-09 | Nano-coating for unsaturated evaporation heat transfer surface |
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| CN2011104074829A CN102492322A (en) | 2011-12-09 | 2011-12-09 | Nano-coating for unsaturated evaporation heat transfer surface |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107490206A (en) * | 2017-09-26 | 2017-12-19 | 重庆重通智远空调设备有限公司 | Transpiration-cooled centrifugal refrigerating machines and its system |
| CN111072084A (en) * | 2019-12-17 | 2020-04-28 | 桂林理工大学 | Seawater desalination system |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1584483A (en) * | 2004-05-24 | 2005-02-23 | 华南理工大学 | Nanometer coating on coiler surface of heat exchanger |
| CN1686890A (en) * | 2005-04-07 | 2005-10-26 | 武汉理工大学 | One-step treatment process of sol filming for preparing toughening self-cleaning glass with film of titanium dioxide |
| CN1916235A (en) * | 2006-09-06 | 2007-02-21 | 浙江大学 | Method for preparing composite film of silver Nano granule / titanium dioxide |
-
2011
- 2011-12-09 CN CN2011104074829A patent/CN102492322A/en active Pending
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1584483A (en) * | 2004-05-24 | 2005-02-23 | 华南理工大学 | Nanometer coating on coiler surface of heat exchanger |
| CN1686890A (en) * | 2005-04-07 | 2005-10-26 | 武汉理工大学 | One-step treatment process of sol filming for preparing toughening self-cleaning glass with film of titanium dioxide |
| CN1916235A (en) * | 2006-09-06 | 2007-02-21 | 浙江大学 | Method for preparing composite film of silver Nano granule / titanium dioxide |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107490206A (en) * | 2017-09-26 | 2017-12-19 | 重庆重通智远空调设备有限公司 | Transpiration-cooled centrifugal refrigerating machines and its system |
| CN111072084A (en) * | 2019-12-17 | 2020-04-28 | 桂林理工大学 | Seawater desalination system |
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Application publication date: 20120613 |