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Aluminum alloy heat exchanger on the car

Aluminum is the material of choice for heat exchangers on various vehicles, and is popular because of its low cost, high heat transfer efficiency, and long life. A modern high-performance passenger car has seven individual heat exchangers, which are mainly used to meet the special needs of the car and can be divided into several categories according to the usage. Taking engine and transmission coolers as an example, including radiators and oil coolers, several designs of the devices are as follows:

1.Mechanically assembled heat sink

The tubes in this type of radiator are round or oval and made of common alloys. Mechanically assembled heat sinks are less expensive to produce, but work less efficiently due to the geometrical limitations of the heat sink itself. This type of radiator is generally used in cars that work in close quarters.

2.Brazed radiator

The tube of the brazed radiator is shoulder-shaped. One side is a clad brazing plate that is rolled and seam-welded. The heat sink is not covered, and it is made by folding the tape with a machine and then drilling heat dissipation holes. Brazed radiators may consist of one or more rows of tubes with a total core thickness not greater than 20mm.

3.Oil cooler

It can be made in many ways, but the two most commonly used are deep-drawn ring and serpentine brazed structures.

4.Climate controller

Heated core. The heater core is actually a simple small radiator, which can be made by brazing or mechanical assembly.

5.Swallow hair dryer

The cooling device in the automobile air-conditioning system can be made by brazing or mechanical assembly, but it is gradually developing in the direction of brazing. Brazed evaporators come in two basic forms:

(1) serpentine tube type

The tube is extruded from a common alloy, yet bent into a serpentine shape, inserted into corrugated fins made of two hundred clad brazeable sheets, and then brazed to form a cooler.

(2) deep drawing ring plate type

It consists of a brazable sheet clad on both sides, the ends of which are deep-drawn into rings. When brazing, the annular part of the plate is the two ends of the evaporator. A large amount of coolant between the ends can flow on the corrugated surface on both sides of the brazing plate. The fins are made of uncovered corrugated, vented strip.

(3) An evaporator made of plate fins and tubes

The front end of the evaporator is fitted with a tube with a return bend (like a “hairpin”) to allow the coolant to circulate.

Among the automotive heat exchangers, the first aluminum components are heat sinks, which are mainly used in mechanically assembled plate/copper tube condensers and evaporators in air conditioning systems. Copper tubes will eventually be replaced by aluminum tubes. replace.

Manufacture of car radiators

The first brazed aluminum heat exchangers for automobiles were produced using the salt dip brazing method. This method involves immersing the entire heat exchanger in a molten salt bath, which acts both as a flux and at the same time increases the temperature (~600°C) during brazing of the assembly. The main disadvantage of this method is that the flux residue must be completely removed, because the residue is corrosive.

The problems in the salt solution immersion brazing method have prompted the research and development of other brazing methods, of which the vacuum brazing method is the most widely used. The radiator is located at the front end of the vehicle and is subjected to a very harsh road environment, including rainwater, salt volatilized from the road surface, exhaust fumes from cars, sand, dust and mud pollution. The radiator contains cooling water and is in contact with miscellaneous metals that may contain components that are detrimental to the corrosion of aluminum, and the entire radiator system is subjected to repeated thermal cycles and vibrations during service life. These pose serious challenges to both materials and welding methods. Practice has proved that vacuum brazing is of extremely high quality and can produce high-quality car coolers.

The brazing furnace selected in vacuum brazing is a crucial factor to ensure the quality of the finished product. The RHVB vacuum high-temperature brazing furnace produced by SIMUWU has the advantages of good temperature control accuracy and high heating uniformity, and is an excellent product for handling high-temperature brazing processes. Under the premise of selecting appropriate process parameters, high-quality vacuum brazing can be realized.