Refrigerant distributor of micro-channel heat exchanger
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Solution Overview
Problem
In HVAC systems, micro-channel heat exchangers face challenges in evenly distributing refrigerant to their tubes, leading to reduced thermal performance and increased pressure drop, especially in long tubes, which affects heat exchange efficiency.
Innovation Solution
A refrigerant distribution structure with internal orifices and flow valves positioned inside the header of the micro-channel heat exchanger, allowing for optimized refrigerant distribution by controlling the flow of liquid refrigerant into the tubes, potentially eliminating the need for an expansion valve and improving evenness of distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If refrigerant is distributed into micro-channel tubes from a header without an internal distribution structure, then the device complexity is reduced, but the refrigerant distribution uniformity deteriorates
Solution Approach 1:
The header is segmented into multiple distribution regions with individually controllable orifices. Each orifice can be independently adjusted to optimize refrigerant flow to different tube sections, achieving uniform distribution without requiring complete structural redesign of the entire header system.
Solution Approach 2:
Different sections of the header are equipped with orifices having different sizes, shapes, or flow resistance characteristics tailored to local requirements. This local customization compensates for variations in tube length, distance from refrigerant source, and thermal load distribution along the heat exchanger.
2Manufacturing precision
If the number of orifices in the refrigerant distributor is increased, then the refrigerant distribution uniformity is improved, but the device complexity increases
Solution Approach 1:
A single refrigerant distributor component integrates multiple orifices of varying configurations within one structure. This multi-functional design allows the distributor to handle different refrigerant flow requirements for multiple tubes simultaneously, reducing the total number of separate components needed.
Solution Approach 2:
Multiple orifice functions are merged into a single distributor body that can be installed as one unit in the header. The combined structure achieves comprehensive refrigerant distribution control without requiring multiple separate devices or complex assembly procedures.
3Manufacturing precision
If orifices are positioned farther from the refrigerant inlet, then the refrigerant distribution uniformity is improved, but the pressure drop increases
Solution Approach 1:
The orifices are designed with variable parameters including different diameters, shapes, and flow resistance characteristics. By adjusting these parameters, the system compensates for the increased pressure drop associated with longer flow paths, maintaining both uniform distribution and acceptable pressure levels.
Solution Approach 2:
Orifices positioned at different distances from the inlet are designed with asymmetric characteristics - those farther away have larger effective flow areas or lower resistance to compensate for the longer path. This asymmetric design balances the pressure distribution across all tubes despite varying distances from the refrigerant source.
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 enhances the thermal performance of micro-channel heat exchangers by ensuring even refrigerant distribution, reducing pressure drops, and improving heat exchange efficiency, particularly in heating and cooling cycles.
Implementation Method 1
The internal structure may include at least one orifice. The refrigerant distribution structure may be configured to receive refrigerant in a liquid state and deliver the liquid refrigerant to the orifice to distribute into the header of the MCHEX.
Implementation Method 2
The flow valve may have an open state and a closed state, where the open state may be configured to generally allow refrigerant to flow through the flow valve and the closed state may be configured to generally prevent a refrigerant flow through the flow valve.
Implementation Method 3
A typical MCHEX may include micro-channel tubes running in parallel between two headers. The adjacent tubes generally have fan-fold fins brazed in between. Refrigerant can be distributed into the micro-channel tubes from one of the headers. Outer surfaces of the micro-channel tubes and the fins may help heat exchange between the refrigerant in the micro-channel tubes and the environment.
Implementation Method 4
The two-phase refrigerant is then typically directed into an evaporator, where the two-phase refrigerant exchanges heat with air in a room to be cooled. During the heat exchanging process, the two-phase refrigerant usually absorbs heat and is vaporized in the evaporator.
Implementation Method 5
The condenser may be configured to facilitate heat exchange between the compressed refrigerant and the environment and condense the compressed refrigerant vapor into liquid refrigerant.
Data Source
AI summary
Embodiments of a refrigerant distributor for a micro-channel heat exchanger (MCHEX) are described. The refrigerant distributor may be configured to have orifices and/or a flow valve that are inside a header of the MCHEX. The MCHEX can be used as an evaporator in a cooling cycle, where refrigerant is distributed into the header(s) through the orifices and the flow valve may be generally in a closed state that generally prevents a refrigerant flow through the flow valve. In a heating cycle, the flow valve of the refrigerant distributor may be configured to be in an open state that allows the refrigerant to flow into the refrigerant distributor and to be directed out of the MCHEX through the refrigerant distributor. In some embodiments, the refrigerant distributor may be configured to receive liquid refrigerant, so as to eliminate the need of an expansion valve in a HVAC system.