Auxiliary Header Layout for Uniform Refrigerant Distribution

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Solution Overview

Problem

Existing refrigerant distribution and charge management strategies in heat exchangers, particularly in microchannel heat exchangers, result in refrigerant imbalance leading to performance drops and system shutdowns, exacerbated by the use of microchannel coils with smaller internal volumes.

Innovation Solution

A refrigerant distribution and charge balancing system comprising an auxiliary header fluidically coupled to the first header of the heat exchanger using tube stubs, facilitating even refrigerant distribution and compensating for charge imbalances without significant pressure drop.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If refrigerant is supplied directly to the first header in conventional heat exchangers, then the system structure is simple, but refrigerant distribution is uneven causing performance drops and system shutdowns

Engineering Contradiction:

Improverefrigerant distribution uniformityVSAvoidheader structure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The single first header is segmented into a first header and a second header, with multiple tube stubs distributed across the headers. This segmentation allows refrigerant to be distributed through multiple pathways (supply tube to first header, supply tube to second header, and tube stubs connecting both headers), ensuring uniform refrigerant distribution to all microchannel tubes while maintaining structural simplicity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The tube stubs act as intermediary elements connecting the first header and second header. These stubs provide additional refrigerant distribution pathways, allowing refrigerant to reach all microchannel tubes uniformly. The intermediaries (tube stubs) resolve the distribution imbalance problem without requiring a completely complex new header design.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Volume of moving object

If microchannel coils with smaller internal volumes are used, then the heat exchanger size is reduced, but refrigerant charge imbalance is exacerbated leading to performance drops

Engineering Contradiction:

Improveheat exchanger sizeVSAvoidrefrigerant charge balance

Core Design Contradiction:

Volume of moving objectVSReliability

Solution Approach 1:

The header system is segmented into first and second headers with multiple tube stubs, creating multiple refrigerant distribution pathways. This segmentation compensates for the smaller internal volume of microchannel coils by ensuring balanced refrigerant charge distribution, preventing charge imbalance even in compact heat exchanger designs.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the header system (first header, second header, tube stubs) are designed with specific local characteristics to optimize refrigerant distribution. The tube stubs are positioned and dimensioned to provide appropriate local refrigerant flow rates, ensuring uniform distribution across all microchannel tubes despite the overall compact size.

Inventive Principle:

Principle #3Local quality

3Reliability

If an auxiliary header is added to improve refrigerant distribution, then refrigerant distribution uniformity improves, but pressure drop increases

Engineering Contradiction:

Improverefrigerant distribution uniformityVSAvoidpressure drop

Core Design Contradiction:

ReliabilityVSStress or pressure

Solution Approach 1:

The header system is segmented into first and second headers with distributed tube stubs, creating multiple parallel refrigerant flow pathways. This segmentation reduces the length and resistance of individual flow paths compared to a single long header, thereby reducing overall pressure drop while achieving uniform refrigerant distribution.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The tube stubs extend in a direction perpendicular to the main header axis, creating a three-dimensional distribution network. This dimensional change allows refrigerant to reach all microchannel tubes through shorter, more direct pathways, reducing the total flow path length and associated pressure drop while maintaining uniform distribution.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Data Source

PatentUS12523434B2Refrigerant distribution and charge balancing system for heat exchangers

Publication Date: 2026.01.13 CARRIER CORP

AI summary

A refrigerant distribution and charge balancing system for a heat exchanger and heat pump is disclosed. The system comprises an auxiliary header that is adapted to be fluidically coupled to a first header of the heat exchanger using one or more tube stubs. The auxiliary header is configured at a predefined distance from the first header. The auxiliary header is adapted to be fluidically coupled to a supply tube associated with a refrigerant line of the heat exchanger.