The Impact on Brazing Ring Manufacturering of HETA Distributor Using Smaller Copper OD than 5.0mm
HETA Distributor Project Background
The application of small-diameter air-conditioning technology not only reduces the amount of copper and material costs for air-conditioning, but also reduces the refrigerant charge, making it possible for new environmentally-friendly working fluids (such as R290 and R32) to be applied to air conditioners. Small pipe diameter air conditioners (pipe diameters ≤ 5mm) usually adopt heat exchangers with multiple flow paths arranged in parallel to avoid excessive pressure drop and performance degradation. However, the multi-flow path arrangement will cause uneven refrigerant distribution in each path. In the branch with less liquid refrigerant distribution, the working medium quickly evaporates to gas, and the heat exchange area cannot be effectively used. In the branch with large liquid refrigerant distribution, the overheating of the working medium outlet is very small, even There may be un-evaporated liquid, which deteriorates the heat exchange capacity of the air-conditioning system, thereby reducing energy efficiency. Therefore, a distributor with excellent performance is required to ensure that the refrigerant is evenly distributed to each branch of the heat exchanger.
Research surface: The smaller the dryness of the inlet is, the larger the mass flow is, which is more conducive to uniform flow distribution. The reflective distributor has excellent distribution performance even when installed obliquely, and the best distribution performance when the gas-liquid two-phase flow reaches misty flow. The flow pattern is a circular flow, which is beneficial to the uniform distribution of branch flow at each end. At present, the research on the influencing factors of distribution performance mainly focuses on external factors, such as inlet mass flow, dryness, tilt angle, two-phase flow pattern, etc., and the flow distribution rule under the influence of internal factors such as the type and structure of distributors, and small tubes The structural optimization method of the diameter air-conditioning distributor is studied.
HETA Splitter Project Technology Roadmap
Test surface of the whole machine: No matter the small air volume or large air volume, the heat transfer capacity of the improved sample with small diameter copper tube is the largest. Among them, the heat transfer capacity of the improved model with a small air volume was increased by 2.2% compared with the prototype, and the heat transfer capacity of the sample two with a large air volume was increased by 2.7% compared with the sample one. With the same system power consumption, the COP increased by 2.2% and 2.7%, respectively. The results of the whole machine experiment show that compared with the prototype, the distributor designed by using the optimization method on the air conditioning system can effectively improve the energy efficiency.
Impact of small-diameter copper pipes on the production of copper brazing rings
Because the diameter of the copper pipe is less than 5mm, the inner diameter of the corresponding brazing ring will also become smaller than 5.0mm. Considering the filling amount required for brazing, the diameter of the raw copper wire cannot be reduced significantly. In the case where the wire diameter is basically maintained, the smaller the outer diameter of the ring, the more difficult it is to form and level the traditional spring-type ring, and even exceed the forming limit of the process equipment.
For this reason, the formation of brazing rings requires more consideration to adopt the process of cut-to-length and then forming a ring. But the inherent disadvantage of this process is that the roundness of the finished brazing ring is not good enough, which may affect the assembly of the brazing ring and the subsequent process. Therefore, it is necessary to consider the introduction of additional shaping (rounding and leveling) equipment and processes, resulting in rising costs.
However, as a supplier, the responsibility of the copper brazing ring manufacturer is to overcome difficulties and find a new way, and cooperate with air-conditioning manufacturers to produce products that meet production requirements.
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Note: The article refers to an article published by the Technical Alliance of Refrigeration and Air Conditioner Heat Exchangers on 2019-12-25
