Multichannel Heat Exchanger Manifolds for Even Refrigerant Distribution
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Solution Overview
Problem
In multichannel heat exchangers, the separation of liquid and vapor refrigerant due to density differences and gravity leads to inefficient heat transfer, as vapor-rich tubes absorb less heat, reducing overall efficiency.
Innovation Solution
A heat exchanger design featuring a distributor within the inlet manifold that divides it into an inlet section and a tube distribution section, creating distribution chambers to evenly distribute refrigerant among multichannel tubes, promoting mixed phase flow and preventing preferential flow to certain tubes, thereby enhancing heat transfer efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If refrigerant flows through multichannel tubes in a conventional heat exchanger, then heat transfer occurs, but liquid and vapor refrigerant separate due to density differences and gravity causing uneven distribution and reduced efficiency
Solution Approach 1:
The inlet manifold is segmented into multiple distribution chambers by distributors, with each chamber serving a specific group of multichannel tubes. This segmentation ensures that refrigerant is distributed evenly to each tube group, preventing vapor-rich tubes from forming and maintaining uniform heat transfer efficiency across all tubes.
Solution Approach 2:
Different regions of the inlet manifold are given different functions through the distributors: the first distributor divides refrigerant into different distribution chambers, while the second distributor further distributes refrigerant within each chamber. This local differentiation ensures optimal refrigerant distribution to each tube group based on its specific location and requirements.
2Ease of operation
If vapor refrigerant separates from liquid refrigerant in vertical manifolds, then some tubes receive mostly vapor, but this results in those tubes being unable to absorb much heat
Solution Approach 1:
The distributors are positioned in the inlet manifold to preliminarily distribute refrigerant into different distribution chambers before the refrigerant enters the multichannel tubes. This preliminary action prevents vapor-liquid separation from causing uneven distribution, ensuring that each tube receives an appropriate mix of liquid and vapor refrigerant before entering the tubes, thereby maintaining heat absorption capacity.
3Productivity
If multichannel tubes are used in heat exchangers, then heat transfer is achieved, but preferential flow to certain tubes reduces overall efficiency
Solution Approach 1:
The inlet manifold is divided into multiple distribution chambers by distributors, with each chamber dedicated to supplying refrigerant to a specific group of multichannel tubes. This segmentation prevents preferential flow by ensuring that each tube group receives an equal and appropriate amount of refrigerant, optimizing overall heat transfer efficiency.
Solution Approach 2:
The distributors act as intermediary devices between the inlet manifold and the multichannel tubes. They mediate the refrigerant flow by dividing it into appropriate distribution chambers and further distributing it within each chamber, ensuring even refrigerant distribution among all tubes and preventing preferential flow patterns.
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 design ensures more even distribution of refrigerant across all tubes, improving heat transfer efficiency by preventing vapor-rich tubes from absorbing less heat, thus enhancing the overall performance of the heat exchanger.
Implementation Method 1
a distributor disposed within the first manifold to longitudinally divide the first manifold into an inlet section and a tube distribution section
Implementation Method 2
the refrigerant changes phases while flowing through heat exchangers in which evaporation and condensation occur
Implementation Method 3
Heat exchangers transfer heat by circulating a refrigerant through a cycle of evaporation and condensation
Implementation Method 4
the refrigerant may enter an evaporator heat exchanger as a liquid and exit as a vapor
Implementation Method 5
the refrigerant may enter a condenser heat exchanger as a vapor and exit as a liquid
Implementation Method 6
in heat exchangers containing vertical manifolds, gravity may promote separation of the liquid and vapor refrigerant
Implementation Method 7
Because the vapor refrigerant has a lower density than the liquid refrigerant, the vapor refrigerant tends to separate from the liquid refrigerant
Data Source
AI summary
The present disclosure is directed to heat exchangers with flow distribution manifolds divided into an inlet section and a distribution section by a distributor. The inlet section may have a relatively small cross-sectional area that promotes mixed phase flow of liquid and vapor refrigerant. The manifolds may be used with multichannel tubes with flow path inlet sections that allow refrigerant to enter the flow paths through an outer wall of the tubes. In certain embodiments, a portion of the outer wall is removed to expose the flow paths to a distribution chamber within the inlet manifold. The multichannel tubes extend into the distribution section to partition the distribution section into a series of distribution chambers defined by a pair of adjacent tubes, the distributor, and the inlet manifold. Within each distribution chamber, the refrigerant may be directed into the multichannel tubes through the inlet sections of the multichannel tubes.