Advantages and processing methods of parallel flow condenser

Condenser is an important part in the refrigeration system of air conditioning equipment. Its quality directly affects the performance of air conditioning equipment. According to relevant literature analysis, the heat loss of condenser should account for 35.5% of the heat loss of the whole air conditioning equipment. Therefore, it is of great significance to improve the energy efficiency ratio of air conditioner, reduce its energy consumption, improve the structure of condenser and strengthen its heat transfer. The condensers used in automobile air conditioning system mainly include sleeve type condenser, tube type condenser and flow type condenser.
1) Sleeve condenser is composed of copper tube and aluminum fin. After a period of work, the internal stress between the pipe and the fin will decrease, and the contact stress will decrease correspondingly, which will lead to the reduction of heat exchange efficiency. This is especially true for the automobile air conditioning, because of the car's turbulence and vibration, the internal stress is more prone to fatigue under such conditions, causing the micro loosening between the pipe and the fin. The holes on the fin will also be expanded under strong vibration because of the different vibration frequency of the tube and the fin, which will generate relative motion between each other, which will further aggravate the reduction of heat transfer efficiency, and also bring the increase of working noise and shorten the service life.
2) Tubular condenser uses round flat tube, whose contact circumference between the tube and the refrigerant is much larger than that of the round tube. Therefore, the heat transfer inside the tube is greatly improved. Flat tube has small windward area, favorable flow pattern, good gas dynamic performance and small eddy current zone on the leeward side. Moreover, its structure is compact, and the flat tube fin occupies a small area under the same number of tube clusters. In this way, flat tubes can significantly increase the heat transfer area at the same external dimensions. At the same time, the pipe and fin are aluminum, light weight, low cost, and simplified processing process, reduced coal joint reliability. According to old literature 2], under the same temperature difference and air flow conditions, using elliptical flat tube instead of round tube can increase the heat exchange by 20 ~ 40%, and the size and weight of condenser can be reduced by 18 ~ 40%.
3) Flat tubes are also used in flat-flow condensers. The refrigerant enters the cylindrical manifold through the pipe joint, then shunt into the elliptical flat tube, flows parallel to the opposite manifold, and finally returns to the joint base through the cross-nozzle. The flat tubes are fitted with heat sinks. This condenser has the characteristics of small pressure loss on the air side and the refrigerant side, high heat transfer coefficient, light weight, compact structure and less refrigerant filling, etc., which is more suitable for R134a working medium. According to literature, compared with tubular condenser, under the condition of the same refrigerant, the side pressure drop of the flat-flow refrigerant is only 20% of that of the tubular condenser, and the heat transfer performance can be improved by about 70%.