Microchannel Heat Exchanger Header for Uniform Refrigerant Distribution
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Solution Overview
Problem
Microchannel heat exchangers in air conditioners face challenges with non-uniform refrigerant distribution due to density and viscosity differences between gas and liquid phases, leading to inefficient heat exchange and system fluctuations.
Innovation Solution
The air conditioner design incorporates a separator with gas and liquid distribution pipe groups to ensure equal mass and flow rates of gas-phase and liquid-phase refrigerants, using a separator cavity with baffles and partition plates to prevent separation during flow, and a header structure with communicating chambers to distribute refrigerant uniformly across flat tubes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a microchannel heat exchanger is used to improve heat exchange efficiency and reduce refrigerant charge, then material cost and heat flux density are improved, but refrigerant distribution becomes non-uniform due to density and viscosity differences between gas and liquid phases
Solution Approach 1:
The header is divided into multiple independent cavities by partition plates, with each cavity serving a specific function (inflow, outflow, loop spaces). This segmentation allows independent control of refrigerant flow paths for different phases, preventing mixing and ensuring uniform distribution to multiple flat tubes without gravitational separation
Solution Approach 2:
The separator acts as an intermediary device between the refrigerant source and the flat tubes. It uses partition plates to create distinct gas and liquid flow paths, mediating the refrigerant distribution to eliminate the harmful separation effect caused by density and viscosity differences
2Reliability
If gravity and viscous force act on two-phase refrigerant flow in flat tubes, then phase separation occurs due to density and viscosity differences, but this causes non-uniform refrigerant distribution and system fluctuations
Solution Approach 1:
The loop space structure creates equipotential flow paths where refrigerant can circulate at equal pressure levels. The partition plates ensure that both gas and liquid phases experience equivalent flow conditions, eliminating gravitational separation effects and ensuring uniform distribution
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution improves refrigerant distribution uniformity, enhancing heat exchange efficiency and stability in the air conditioning system by preventing separation and ensuring consistent flow rates across all tubes.
Implementation Method 1
due to a difference in density and viscosity between the gas phase and the liquid phase, the flowing refrigerant is easily separated under action of gravity and viscous force
Implementation Method 2
The function of the heat pump air conditioner is to transfer heat from an outdoor environment to an indoor environment
Implementation Method 3
The microchannel heat exchanger includes flat tubes, fins, headers and end caps
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
An air conditioner. A heat exchanger is provided on a heat exchange loop. The heat exchanger comprises flat tubes (11), a second collecting main (02), a third collecting main (03), and a connecting tube (09). The second collecting main (02) communicates with the third collecting main (03) by means of the connecting tube (09). The second collecting main (02) communicates with the flat tube (11) in a downstream flow of the heat exchanger. The third collecting main (03) communicates with the flat tube (11) in an upstream flow of the heat exchanger. The second collecting main (02) comprises a cavity portion (021), a channel portion (022), and a turbulent flow portion (023). The cavity portion (021) communicates with the connecting tube (09). One end of the channel portion (022) communicates with the cavity portion (021), and the other end communicates with the flat tube (11). The turbulent flow portion (023) is provided in the cavity portion (021), thereby preventing an eddy current from causing a flow blind region in the cavity portion (021), disturbing a flow path of a refrigerant in the cavity portion (021), and facilitating mixing of refrigerants in a high-pressure region and a low-pressure region in the cavity portion (021). Therefore, refrigerants entering different channel portions (022) are evenly distributed, and flow rates of refrigerants in different mind a low-pressure region in the cavity portion (crochannels in the same flat tube (11) and in different flat tubes (11) in the same flow are uniform.