The heat exchange system of automobile includes air conditioner, radiator of water tank, oil cooler, intermediate cooler and heater. They are located at the front part of the car body, and are polluted by the salt and exhaust from the rain, the road, and the pollution from the gravel, dust and mud. They are also subjected to repeated thermal and cyclic vibrations. These have put forward severe challenges to the selection of heat exchanger, antisepsis and combination technology. The traditional heat exchange system is made with copper, however, with the accelerated process of automotive lightweight, energy saving and emission reduction, and reduce the fuel consumption rate increased and alleviate the pressure of environmental pollution, at the same time due to the manufacturing technology and assembly technology, the aluminum gradually replaced copper, widely used in the manufacture of automotive heat exchanger system components.
The aluminum alloys for heat exchangers include 1 series, 3 series, 4 series, 5 series and 6 series alloys. The aluminum materials are: strip and foil (including composite material), extruded pipes and profiles, forgings and bars.
1. Heat shield aluminum sheet plate
In the car's power transmission line, most of the heat shield, more than 60% of the car is equipped with one, and more than 5-6. Usually 0.5mm aluminum alloy plate is used. The most commonly used alloy is 5182 alloy. The other alloys have 1050, 3003, 3004 and 5052 alloy, and aluminum alloy plate is used for making insulation board, which has strong competitiveness.
2. Heat exchange aluminum material
The most aluminum material used in cars is the heat exchanger system, that is, HVAC=heater ventilaton and air conditioning, namely heating, ventilation and air conditioning. The aluminum content of the heat exchange system of each car and light truck is about 15KG. In fact, the heat sink (radiator), the condenser (condenser), the evaporator (evaporator) and the radiator core (heater core) have all been made of aluminum alloy.
3. Tank radiator aluminum material
Radiator is an indispensable part of the cooling system of the automotive water-cooled engine. Its function is to heat the excess heat carried by the cooling medium in the engine jacket through two heat exchanges, and to send it to the atmosphere under the forced air flow. Therefore, the performance of the cooling system radiator is directly related to the performance of the automobile engine, and even whether the engine can work normally, and whether it can drive safely. At present, the radiator is developing towards the direction of thin wall, light weight, high strength, high efficiency and economy.
The aluminum water tank is made up of liquid conduit and radiator fins. The conduit is made of aluminum alloy composite belt by high frequency welding pipe machine. The pipe is welded into a whole through cooling medium, pipe and fins, forming the main body of the water tank. Automatic soldering tank at about 600 ℃ high temperature special furnace, welding tube and fin tube should be stable, deformation at high temperature, otherwise it will produce weld or sealing, unfavorable to the cooling effect. Therefore, the quality of the composite aluminum alloy tape used in the manufacture of ducts has a direct effect on the quality of the water tank.
Usually, the ability to resist gravity and natural droop of aluminum alloy strip during brazing is called the droop resistance of materials, and the natural drooping distance is called droop. It is one of the main indexes to measure the performance of composite materials.
4. Air conditioning radiator aluminum
Radiator used in aluminum composite pipe and fin radiator aluminum foil, including automotive air conditioning evaporator and condenser, the raw material is for 8 x 1mm or 3003 pure aluminum alloy tube and fin aluminum foil, the extruded porous flat tube fin and foil.
4.1 Evaporator aluminum tube
The evaporator aluminum pipe, 1060, 1070, 1050 by 1070A, 1100 of industrial pure aluminum, can also use 3003 alloy by extrusion and drawing processes, mature production technology, the tube size is for 8 * 1mm, you can use ordinary extrusion, can also be used in continuous extrusion machine production, materials for the O or H112 state, the size deviation of ordinary class and high grade atmosphere.
4.2 Condenser tube
The porous flat tube of the condenser is often called the harmonica tube, which is used as a fluid conduit in the heat exchanger and is used in the tube to flow through the cooling medium. The empty number of the tube is generally 5~25 holes. Of course, there are more holes. The wall thickness is 0.6 to 0.8mm, and it can be thinner. The height is 5~6. The harmonica tube is not only thin wall, Kong Duo, but also difficult to squeeze. But between the channels is relatively closed, without breaking the weld defect free, cold deformation, can withstand the pressure of 8 - N/mm.
5. Composite heat dissipating plate, belt, foil
The automotive heat exchanger includes radiator, intercooler, oil cooler, condenser and evaporator. The composite aluminum strip, ribbon and foil are the core materials for their production. Composite radiator aluminum sheet, strip and foil is developed with the development of vacuum brazing technology, can brazing in nitrogen atmosphere in the furnace, the technology is characterized in that the requirements of the radiating fin surface of the composite layer brazing alloy, the melting point of the matrix Aluminum Alloy its low 50 ℃ Celsius, so thermal insulation heat exchanger is arranged on the assembly time good about 600 ℃ after the furnace, the fin base alloy melts as Al-Si alloy solder coating melt left after cooling will put them firmly into one brazing.
Composition of brazing composite material is composed of matrix Aluminum Alloy one side or both sides of composite brazing alloy has low melting point alloy Al-Si or Al-Si-Zn, the thickness of the coating is usually about 10% of the total thickness of composite materials, (core layer) of the matrix alloy melting point of 630 to 660 ℃, coating the melting point of 577 ~ 610 ℃.
The composite heat exchange material aluminum plate, belt and foil can be double layer (base + single layer cortex), three layers (core layer + double layer cortex), four layers (core layer + two layers cortex + one water contact layer), five layers (core layer + upper and lower two layers of cortex).
Automotive cooling composite material is a high-tech product: the thickness of the composite layer should be uniform, the surface without composite layer off, the matrix alloy after brazing, high strength, strong corrosion resistance, good solderability and so on.
The automotive heat exchange materials include composite materials for radiator of water tanks and composite materials used for air conditioning radiators. The tube type radiator is 2.8KG/ with aluminum compound foil, and the air conditioner is 4KG/ with three layers of aluminum alloy foil.