At present air-conditioning are gradually miniaturized, high performance, high-life direction. The air-conditioning heat exchanger corresponding to the thin film and high-intensity direction. 1980 heat film thickness of 0.15-0.2ram, and today only the thickness of between 0.09 to 0.15mm. In addition, in order to improve the life of air conditioning to reduce energy consumption, improve quality and enhance the cooling effect of ventilation, they have developed a heat exchanger with a variety of functional coating film, a typical piece of anti-corrosion heat exchanger, heat transfer surface hydrophilic properties films, heat transfer film and surface hydrophobic properties and self-lubricating film mold heat exchanger tablets.
Classification of air foil:
1, non-coated aluminum foil
Non-coated foil is annealed after rolling, the surface is not subject to any form of treatment foil. China 10 years ago, about 15 years ago, foreign films for air-conditioning heat exchangers are non-coated aluminum foil. Even now, the heat exchanger used in developed countries about 50% is still a non-film-coated aluminum foil, while in China, this ratio is about 60%.
2, coated aluminum foil
The so-called non-coated aluminum foil is coated on the foil surface re-treatment, it has some special features. In Japan, Germany and other rapid technological development of countries, the use of foil-coated more than 15 years of history. In China, the use of coated aluminum foil no more than 10 years.
3, corrosion-resistant aluminum
Corrosion-resistant aluminum surface of the product has a certain anti-corrosion protection layer, air conditioning with heat exchanger made of the product film applied to the more poor, and can significantly improve the life of air conditioning. At the same time as the improvement of corrosion resistance of heat transfer film, greatly reducing the generation of surface corrosion powder, thereby improving the quality of ventilation, air-conditioned indoor air purification.
4, the hydrophilic aluminum foil
Hydrophilic aluminum foil has a strong hydrophilic surface. The quality of the hydrophilic properties of the water stick to the foil surface, the angle formed by the size of the decision, as shown in Figure 1. a smaller angle is better hydrophilic properties, hydrophilic properties and vice versa worse. In general, a angle less than 35. That is hydrophilic properties. Hydrophilic aluminum foil is generally used in air conditioning condenser. Its main function is to heat the water in the heat exchanger in the air condenses into water droplets when the chip easy to spread out and go down to the downstream sheet. This prevents water drops due to heat transfer between the film "bypass" and affect the heat exchanger ventilation, air conditioning heat exchange to improve the rate of cooling capacity in the same condition can also save energy. Currently, the market in general has good hydrophilic aluminum foil in addition to the hydrophilic surface, but also the high corrosion resistance, making air conditioning more optimized performance.
5, hydrophobic aluminum foil
Called hydrophobic hydrophobic aluminum foil, aluminum foil hydrophilic surface properties and the exact opposite. The condensed water condensed to the surface with aluminum foil the foil into a larger contact angle, usually 75. Or more. The exclusion of water the greater the angle the better the performance. The ultimate goal of using hydrophobic and hydrophilic aluminum foil aluminum foil same as that retained in the heat exchanger to prevent condensation of water between the pieces. The difference is, is water-repellent foil and heat transfer through the condensate film to increase the contact angle, so that the formation of condensed water droplets easily slipped in between films to achieve the removal of condensation heat transfer purposes.
6, self-lubricating aluminum foil
Air conditioning heat exchanger in the processing of film production process is generally first in lubricating the surface, and then punching flanging, TCE will last and then wash away the oil. Because TCE are harmful, so in order to reduce this process, gave rise to the corresponding self-lubricating aluminum foil. Self-lubricating aluminum foil name suggests, is in the red when the system does not require separate processing lubricating the lubrication system for its red foil surface by the pre-treatment of the membrane to bear. Since no special lubricating, therefore eliminating the need for subsequent cleaning and drying processes trichlorethylene.
7, mold aluminum foil
Mold aluminum foil is mainly used for air conditioning and some of the indoor unit, its main function is to prevent the use of heat transfer film or place a long time and produce surface mold, thereby significantly improving the quality of air conditioning and ventilation, prevent abnormal smell, effective improve the indoor air environment.
Third, the non-coated air foil of the main technical indicators:
1, the chemical composition:
Heat transfer sheet with aluminum foil alloy grades are 1100,1200,8011,8006 and so on. On the use of point of view, air conditioning, aluminum heat sink on the chemical composition is not strictly required. No surface treatment in the case, 3A21 aluminum alloy is relatively good corrosion resistance, mechanical strength and elongation properties of high hardness is also large. Choice of which depends on alloy material can reach the final mechanical properties and ease of ant process. Such as high purity 1100 aluminum rolling easier, and 8011 alloys are more difficult.
2, the mechanical properties:
Mainly refers to the mechanical properties of aluminum foil tensile strength, elongation and Erichsen value. From the use of perspective, I hope these three indicators as high as possible, but the material itself, these three indicators and contradictory, that is, when a relatively high tensile strength aluminum foil, the elongation index will decline; and aluminum foil to improve the extension rate, would lead to a decline in tensile strength. Therefore, in practice, generally the mechanical properties of intermediate values, and specific strength and ductility values and film processing and heat transfer of punching die for. General heat transfer sheet punching process is divided into tension-type and two kinds of stretching. Stretched requirements of the mold punching of plastic foil better, that is, high elongation, the relative intensity values can be slightly less; without the mold with the required tensile strength of higher aluminum foil, plastic is a secondary target. Factors affecting the mechanical properties of aluminum foil large, mainly aluminum foil chemical composition and processing. On the strength and ductility for aluminum foil, or by adjusting the chemical composition changes in process flow and parameters, you can make within a certain range or intensity of the plastic material to keep the party in the case of constant change to the other. In other words, the chemical composition and processing through the adjustment can be limited to changes in aluminum foil mix of strength and ductility values.
Heat transfer film according to the requirements for mechanical properties, the current state of the main uses of aluminum foil, there are three: H22, H24, H26. Each state corresponds to a certain degree of strength and plastic range. From the current status of the domestic aluminum industry point of view, for the range of mechanical properties of each state there is no uniform standard. At the same time in the practical application range of the mechanical properties of each state is too wide, can not control the mechanical properties, in order to achieve that degree of user satisfaction. Table 1 is a typical heat exchanger Used for aluminum alloys and mechanical properties of the state value.
Fourth, the coated air foil of the main technical indicators:
Foil is coated on the basis of non-coated aluminum foil formed after surface treatment, in addition to non-coated aluminum foil with the requirements of the chemical composition, mechanical properties and geometry and other performance indicators, should have a good plate and coating performance.
1, aluminum foil plate:
First, the coating of aluminum foil aluminum foil production process have a good plate, which is a prerequisite for the production of coated aluminum foil. Indicators to measure plate unit is I. General coating of the plate production equipment requirements are less than 20-40I, if greater than this value, you need equipment in front of a tension coating straightening system. Aluminum coating equipment, the general run of its routes are longer, the treatment process and the guide roller is greater. Therefore, if not equipped with tension straightening system, once the plate is not good it is easy to play in the run off, resulting in no production. Air conditioning of the production process of aluminum foil plate have higher requirements. Average heat transfer sheet punching production line are conducted using a vacuum suction transfer foil, aluminum foil plate is not good if the surface is not flat, it will lead foil vacuum suction delivery method does not work correctly. Therefore, the plate is not only coated aluminum foil, coated aluminum foil is also an important non-technical indicators.
2, coating performance:
As mentioned above with the coating film heat exchanger has many kinds of aluminum foil on the market today is mainly used in coating aluminum foil hydrophilic aluminum foil, so far as here, hydrophilic aluminum foil coating performance indicators discussed.
3, the coating thickness:
Foil surface coating thickness is not a hard requirement, generally in the 3/1m below. Because the price is generally more expensive paint, so to meet the performance requirements under the premise of the more thin film thickness control, lower production costs. Directly affect the coating thickness of the coating performance, thus requiring foil surface coating thickness uniform.
4, coating adhesion:
Coating adhesion is coated with aluminum foil adhesive fastness indicators. If the coating adhesion is too small, then the coated aluminum foil and use in further processing, surface coating is easy to fall off, which would seriously affect the weight of aluminum coating, thus requiring the stronger the better coating adhesion. Coating adhesion is generally only qualitative testing, the main detection methods abrasion test, cross-cut test and cupping method.
5, the hydrophilic properties:
Hydrophilic aluminum foil in use for some time, because by leaving the role of various environmental factors affect the surface of the hydrophilic properties. Therefore, the hydrophilic properties are generally divided into hydrophilic and resistant to the initial test of the hydrophilic properties of the environment. The quality of the hydrophilic properties mainly to measure the size of a corner. General product requirements of the initial hydrophilic a<100, resistance to environmental test requirements of hydrophilic a <250. Contact angle measurements can choose a specific contact angle measuring instrument; can also be a certain amount of volume of water droplets on the surface of aluminum foil the size of the occupied area calculated.
6, the corrosion resistance:
Corrosion resistance is mainly reflected in three aspects: First, alkali resistance, due to heat transfer surface of the sheet after punching alkaline detergent to remove oil required, so the requirements of aluminum foil surface coating must have a certain function of alkali , generally requires a 20% NaOH solution soak 3 minutes without foaming; second is resistant to salt spray corrosion, usually in the experimental conditions of 35 oC, 3% of the salt spray environment can not have the required 500 hours corrosion spots . Salt spray corrosion resistance, good or bad life is directly related to the length of heat transfer film. In coastal areas, due to the high salinity in the air, so the heat sink has a higher corrosion resistance to salt spray requirements; third is heat-resistant properties, which in a certain temperature and humidity for a long time to place a certain resistance to corrosion of. The performance is the ability to measure heat transfer film resistance is an important indicator of climate.