Fluid Distributor Cavities for Microchannel Heat Exchanger Mal-Distribution
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Solution Overview
Problem
Mal-distribution of working fluid in microchannel heat exchangers (MCHX) leads to imbalances in thermal characteristics and reduced heat transfer efficiency, particularly in systems with vertical headers where gravity causes vapor-liquid separation.
Innovation Solution
A fluid distributor for heat exchangers featuring a header with compartments, a distribution tube with longitudinal cavities and ports, and a supply tube connected to the distribution tube, optionally including a flow restrictor and a swirl generator to ensure uniform fluid distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a conventional fluid distribution system is used in microchannel heat exchangers, then the structure is simple, but the working fluid distribution is non-uniform leading to reduced heat transfer efficiency
Solution Approach 1:
The distribution tube is segmented into multiple cavities (first cavity, second cavity, etc.) that are radially arranged around the central axis. Each cavity independently distributes fluid to different sets of microchannel tubes, ensuring uniform flow distribution across all tubes while maintaining a relatively simple overall structure.
Solution Approach 2:
The invention transitions from a conventional single-channel distribution approach to a multi-cavity radial distribution system. The cavities are arranged radially around the central axis of the distribution tube, creating a three-dimensional distribution pattern that improves fluid uniformity across the heat exchanger tubes.
2Volume of moving object
If vertical headers are used in heat exchangers, then the installation space is optimized, but vapor-liquid separation occurs due to gravity causing mal-distribution
Solution Approach 1:
The distribution tube with multiple radially arranged cavities is positioned upstream in the vertical header to pre-distribute the fluid before vapor-liquid separation can occur. This preliminary distribution action ensures that all microchannel tubes receive uniform fluid flow even in vertical configurations where gravity causes phase separation.
Solution Approach 2:
Different cavities in the distribution tube serve different local regions of the heat exchanger. Each cavity is optimized to distribute fluid to specific sets of tubes, ensuring that local fluid distribution requirements are met despite the vertical orientation and gravitational effects on vapor-liquid separation.
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
The fluid distributor achieves a more uniform distribution of working fluid across microchannel tubes, enhancing overall thermal performance and capacity by minimizing mal-distribution and vapor-liquid separation issues.
Implementation Method 1
the fluid distributor comprises a flow restrictor configured within the supply tube or between the supply tube and the distribution tube, wherein the flow restrictor is an annular member having a central opening that is configured in line with the distribution tube and having a predefined gap therebetween
Implementation Method 2
the swirl generator is configured to cause the working fluid, supplied by the supply tube, to move in a swirl motion
Data Source
AI summary
A fluid distributor for a heat exchanger is disclosed. The fluid distributor comprises a header having compartments. A plurality of MCHX tubes associated with a heat exchange section of the heat exchanger are fluidically connected to at least one of the compartments. The fluid distributor further comprises a distribution tube extending longitudinally along the compartments through the walls. The distribution tube comprises a plurality of cavities extending longitudinally along the length of the distribution tube and configured radially around a central axis of the distribution tube. Each cavity comprises ports opening in a compartment. Further, the fluid distributor comprises a supply tube fluidically connected to the distribution tube or to a supply tube compartment of header and configured to supply a fluid into the distribution tube.