Microchannel Heat Exchanger Uniform Fluid Distribution
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Solution Overview
Problem
Existing microchannel heat exchangers face challenges in achieving uniform fluid distribution across all microchannel tubes, leading to inefficiencies in heat transfer due to airflow maldistribution and pressure field maldistribution.
Innovation Solution
The proposed heat exchanger design includes a V-coil configuration of microchannel tubes with an external distributor and feeder pipes that supply fluid to the inlet header, and an auxiliary header fluidically coupled to the outlet header via tube stubs, which helps in uniform fluid distribution and pressure management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional microchannel heat exchanger design is used, then the structure is simple, but uniform fluid distribution across microchannel tubes cannot be achieved
Solution Approach 1:
The inlet header is divided into multiple compartments (first compartments) that are separated by partition walls. Each compartment receives fluid from specific outlet ports of the distributor through dedicated feeder pipes, enabling independent control and uniform distribution of fluid to different sections of microchannel tubes.
Solution Approach 2:
Feeder pipes act as intermediary components connecting the distributor outlet ports to the inlet header compartments. These feeder pipes are strategically positioned along the inlet header to mediate fluid transport and ensure uniform distribution across all microchannel tubes by controlling flow paths and pressure drops.
2Manufacturing precision
If fluid is supplied directly to inlet header without distributor, then the device complexity is reduced, but airflow maldistribution and pressure field maldistribution occur
Solution Approach 1:
The distributor is designed with non-uniform outlet ports having different sizes and configurations tailored to specific locations. Outlet ports at different positions along the inlet header have varying dimensions to compensate for pressure drops and ensure uniform fluid distribution across all microchannel tubes despite their different distances from the inlet.
Solution Approach 2:
The feeder pipes have non-uniform diameters and lengths that are optimized based on their positions along the inlet header. By varying these geometric parameters, the pressure drop across each feeder pipe is controlled to achieve uniform fluid distribution and eliminate pressure field maldistribution in the microchannel tubes.
3Productivity
If outlet header collects fluid from all microchannel tubes, then the fluid collection is complete, but airflow maldistribution affects heat transfer efficiency
Solution Approach 1:
The microchannel tubes are arranged in a V-coil configuration that introduces a spatial dimension to the flow path. The tubes extend between the inlet and outlet headers in a curved pattern, creating a more uniform distribution of airflow across the heat exchange surface and improving thermal contact with the fluid flowing through the tubes.
Solution Approach 2:
The outlet header is designed with multiple outlet ports positioned at different locations to create equipotential conditions for fluid collection. By strategically placing outlet ports and using tube stubs of appropriate lengths, the system ensures uniform pressure distribution and complete collection of fluid from all microchannel tubes, eliminating maldistribution effects.
4Ease of manufacture
If inlet header and outlet header are positioned at same vertical height, then the installation is simplified, but the V-coil configuration requires adequate space
Solution Approach 1:
The microchannel tubes are configured in a V-coil pattern with smooth curved bends instead of sharp angles. This curved configuration allows the tubes to efficiently navigate the space between the inlet and outlet headers positioned at the same vertical height, achieving compact arrangement while maintaining uniform flow distribution and adequate heat exchange surface area.
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 design enhances the thermal performance of the heat exchanger by ensuring uniform fluid distribution across all microchannel tubes, mitigating airflow and pressure maldistribution issues, and improving overall heat transfer efficiency.
Implementation Method 1
a plurality of microchannel tubes extending between and in fluidic connection with an inlet header and an outlet header
Implementation Method 2
mixing of an incoming airflow coming from a bottom side of the plurality of microchannel tubes
Implementation Method 3
the feeder pipes have non-uniform diameters and lengths such that a target pressure drop is achieved in the feeder pipes
Implementation Method 4
one or more tube stubs protruding from the outlet header and extending up to the auxiliary header
Data Source
AI summary
The heat exchanger comprises a plurality of microchannel tubes in fluidic connection with an inlet header and an outlet header, and an external distributor that comprises an inlet port and a plurality of outlet ports, wherein a plurality of feeder pipes is configured between the outlet ports of the first distributor and positioned along a length of the inlet header to enable flow of volumes of fluid from the distributor into the inlet header. Further, an auxiliary header is fluidically coupled to the outlet header using tube stubs. The auxiliary header is configured at a distance from the outlet header with the tube stubs protruding from the outlet header and extending up to the auxiliary header forming an angle from a horizontal plane of the outlet header, wherein the auxiliary header is configured to receive and collect the fluid received in the outlet header.