Evaporator is one of the key components in refrigeration systems such as refrigerators and freezers. The traditional evaporator pipes are all copper pipes, which have low leakage rate but high production cost. In recent years, in order to reduce the production cost, many refrigeration enterprises have gradually changed the traditional all-copper tube into copper-aluminum tube or all-aluminum tube. However, due to the activity of aluminum, the thin corrosion-resistant oxide film on the surface, and the influence of other factors such as the use environment, such products are prone to copper-aluminum pipe leakage and aluminum pipe corrosion during use, which in turn leads to internal leakage of the evaporator, resulting in the overall failure or even scrapping of refrigerators and freezers, which brings serious losses to manufacturers and consumers. At the initial stage of popularizing the technology of replacing copper with aluminum, there were many leakage faults in copper-aluminum joints. After the patent technology of casing extrusion resistance welding was introduced, the leakage failure of copper-aluminum joint gradually decreased, but the corrosion problem of aluminum pipe was not effectively solved, and it was aggravated. Judging from the information available at present, a few documents only made a preliminary analysis of the causes of internal leakage of aluminum tubes in evaporators, without in-depth study of the serious influence of environmental media on the corrosion mechanism of aluminum tubes, and rarely put forward targeted and effective solutions. Therefore, it is of great significance to analyze the corrosion mechanism of aluminum tube of evaporator for fundamentally solving the internal leakage problem of evaporator.
What kind of refrigerator evaporator is good?
There are five kinds of evaporators commonly used in refrigerators: fin coil type, aluminum plate inflatable type, steel wire coil type and single-ridge fin tube type.
1, finned coil evaporator.
Fin-coil evaporator is an indirect cooling evaporator. It is only suitable for indirect cooling refrigerators. In this device, aluminum tubes or copper tubes with a diameter of 8- 12 mm are mostly used as tubular parts, and aluminum sheets (or copper sheets) with a thickness of 0. 15-3 mm are used as fin parts, and the fin spacing is 8- 12 mm. The tubular part of this evaporator is used for the circulation of refrigerants, and the fin part is used for absorbing the heat of refrigerating and freezing rooms. Fin-coil evaporator is widely used because of its high heat transfer coefficient, small occupied space, firmness, reliability and long service life.
2. Aluminum plate inflatable evaporator.
It adopts printing pipes between two aluminum plates, calendering and hot pressing the unprinted parts into a whole, and then inflating at high pressure to form a bamboo road. This evaporator is used in L-flash single-door refrigerator freezer, double-door refrigerator freezer and small address double-door refrigerator freezer, and is installed in the upper part of the back wall of the refrigerator in the form of a flat plate.
3. Tube plate evaporator.
It is made by bending a copper tube or an aluminum tube (generally 8mm in diameter) into a certain shape and then bonding (or brazing) it with a composite aluminum plate. Among them, the copper tube is used for the circulation of refrigerant; Aluminum plate is used to increase the conductive area. This evaporator is often used for direct cooling of freezer evaporator and direct cooling refrigerator.