1. What is an automotive heat exchanger
A heat exchanger refers to a device that transfers heat from a hot fluid to a cold fluid, and is used in automobiles and construction machinery vehicles Extensive, there are many varieties of heat exchangers on automobiles, including radiators (commonly known as water tanks), intercoolers, oil coolers, automotive air conditioning condensers and evaporators, warm air radiators, exhaust gas recirculation system (EGR) coolers , hydraulic oil cooler, etc., which belong to the engine, gearbox, body and hydraulic system on the car.
Second, the structure of automobile heat exchangers
There are many kinds of automobile heat exchangers, but the structure can be roughly divided into four types:
1. Tube fin type
The tube fin structure is a conventional structure that combines aluminum fins and copper tubes, and the aluminum fins are in the process of expanding the tube. Adhesion to each other with copper pipes. The advantages are simple processing, mature technology and low cost. The disadvantage is that the vibrations caused by the movement of the car cause loosening between the segments. At the same time, the alternating temperature changes result in different degrees of thermal expansion and contraction of the tubes and fins, resulting in poor contact between the fins, thereby increasing thermal resistance and reliability, and reducing performance and life. At the same time, when applied to an evaporator, if the tube wall temperature is lower than the dew point temperature of the air, the air passing through the surface of the evaporator tube will condense on the surface, and the appearance of condensed water will also increase the thermal resistance. Inadequate drainage also limits their use in automotive air conditioners. At present, heat exchangers with this structure are not used in automobile air conditioning systems, and mainly some large passenger and engineering vehicles use evaporators.
2. Tube and strip type
The tube and strip structure is developed on the basis of the original tube slice structure, using mechanical methods to process aluminum alloy materials into Tubular structures, transformed into equidistant meandering tubes, using machining methods to connect the tube sheet structure, and finally forming a permanent connection foam. This type of heat exchanger connection method guarantees the needs in the automotive forming process, has a longer working time than the segment type, and further improves the heat exchanger performance. However, this structure has poor heat exchanger performance in use, and the process of manufacturing the multi-channel tubes is more complicated. Therefore, tube-and-belt heat exchangers are rarely used in actual automotive air conditioners.
3. Parallel flow
The structure of the parallel flow heat exchanger is designed to be based on a tube-and-belt condenser in one or both directions The refrigerant is changed in series, or in parallel in two directions for multiple inflows and outflows. Flat tube extrusion technology, shutter fin forming technology and vacuum welding technology are also used. Parallel flow condensers consist of shunt tubes, flat tubes and manifolds. The refrigerant for each process flows through the manifold, enters multiple flat tubes for heat exchange (each flat tube has multiple channels), enters the manifold at the end of the flat tubes, and then redistributes to the next process will be done. Due to the slow cooling, the volume flow of refrigerant is reduced, so the number of flat tubes in each row is gradually reduced. The cross section of the flat tube flow channel is rectangular, triangular or circular, and the inner wall is a smooth tube or inner fin. Between the flat tubes are corrugated fins with baffles. As the third generation of automotive air conditioning heat exchangers, the development of automotive air conditioning systems is remarkable.
4. Cascaded
Cascaded heat exchangers retain the working characteristics of tube-fin heat exchangers and tube heat exchangers. On this basis, the U-shaped plate heat exchanger is designed to form a new type of air conditioning heat exchanger system. During processing, this type of heat exchanger is corrugated on the plate. This ensures the cooling performance of the air conditioning system and allows it to exchange heat with the air inside the vehicle during operation. Various shapes of aluminum fins, such as corrugated fins and perforated fins, are also being designed in the car company’s ongoing designs.
Three, what is the working principle of automobile heat exchanger
The structure of automobile heat exchanger is diverse, but the basic working principle is the same:
What is the working principle of automobile heat exchanger
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When working, the compressor compresses the refrigerant into a high-pressure saturated gas (ammonia or freon), and this gaseous refrigerant is condensed by the condenser of the car, throttled through the throttling device, and then passed to the evaporator In the medium, the medium to be cooled is cooled and heat exchanged; and the refrigerant in the coiled tube of the evaporator after heat exchange becomes a low-pressure vapor and returns to the compressor, and then is compressed by the compressor. The principle of heating and refrigeration is the same, that is, the reverse Carnot cycle. The difference from the refrigeration principle is the exchange of the condenser and the evaporator, namely: compressor-evaporator-throttle device-condenser.
