Heat Exchanger Flow Distributor for Two-Phase Maldistribution Control
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Solution Overview
Problem
Conventional parallel flow heat exchangers, particularly those with multi-channel tubes, suffer from fluid maldistribution due to differences in densities of liquid and vapor phases in two-phase fluid flow, leading to performance degradation in refrigeration and air conditioning systems.
Innovation Solution
A longitudinally elongated distributor manifold with a distributor body having discrete flow passages, including longitudinally and transversely extending passages, is used to distribute fluid uniformly among heat exchange tubes, ensuring equal fluid flow to each tube by adjusting pressure drop and flow communication through discharge ports and slots.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional parallel flow heat exchangers with multi-channel tubes are used, then the heat exchanger structure is simple and easy to manufacture, but fluid maldistribution occurs leading to performance degradation
Solution Approach 1:
The distributor is segmented into a manifold portion and a separate distributor body with discrete flow passages. The distributor body is divided into multiple flow passages (first, second, third flow passages) that independently control fluid distribution to different tubes, allowing precise flow control while maintaining manufacturing simplicity.
Solution Approach 2:
The distributor acts as an intermediary component between the manifold and the heat exchange tubes. It mediates the two-phase fluid flow by providing a structured distribution mechanism that equalizes flow among tubes, preventing maldistribution without requiring complex system-level modifications.
2Productivity
If two-phase fluid flow is delivered to the fluid chamber for distribution amongst tubes, then the heat exchanger can perform refrigeration/air conditioning functions, but density differences between liquid and vapor phases cause flow maldistribution
Solution Approach 1:
Each flow passage in the distributor is designed with specific local characteristics (different cross-sectional areas, lengths, and configurations) to compensate for the density differences between liquid and vapor phases. The first, second, and third flow passages have tailored geometries that locally adjust flow resistance to achieve uniform distribution despite the two-phase nature of the fluid.
Solution Approach 2:
The distributor utilizes changes in flow parameters (pressure drop, flow velocity, phase distribution) across different passages to achieve uniform distribution. By designing passages with varying hydraulic resistances, the system compensates for density differences and maintains reliable fluid distribution throughout the heat exchanger.
3Reliability
If an elongated distributor tube is inserted within the inlet manifold to reduce two-phase flow maldistribution, then flow distribution improves, but the device complexity increases and manufacturing becomes more difficult
Solution Approach 1:
Rather than using a single complex elongated distributor tube, the invention segments the distribution function into a manifold portion and a separate distributor body with discrete flow passages. This segmentation simplifies manufacturing by allowing each component to be produced independently using standard techniques, then assembled together.
Solution Approach 2:
Instead of inserting a complex tube into the manifold, the invention inverts the approach by having the distributor body with pre-formed flow passages interface with the manifold. The flow passages are created within the distributor body structure itself rather than requiring insertion of a separate tube, simplifying both manufacturing and assembly.
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 minimizes maldistribution of liquid and vapor phases, enhancing heat exchanger performance, improving the coefficient of performance, reducing power consumption, and allowing for smaller and lighter evaporators in refrigeration and air conditioning units.
Implementation Method 1
ensuring equal fluid flow to each tube by adjusting pressure drop and flow communication through discharge ports and slots
Implementation Method 2
a plurality of spaced parallel passages for conveying a first fluid in heat exchange relationship with a second fluid
Implementation Method 3
gravity forces may separate the liquid and vapor phases as the two-phase mixture passes along the length of the manifold
Implementation Method 4
flow maldistribution in two-phase flow heat exchangers may primarily be attributed to the difference in densities of liquid phase and the vapor phase
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
A heat exchanger includes a distribution manifold, a plurality of longitudinally spaced tubes having inlet ends opening into the manifold, and a longitudinally extending distributor body disposed within the manifold. The distributor body has a first surface juxtaposed in spaced relationship with the inlet ends of the plurality of tubes and a second surface interfacing with the manifold inner wall. A plurality of discrete flow passages extend from an inlet end of the distributor body and open through the first surface of the distributor body. The plurality of discrete flow passages includes a plurality of longitudinally extending flow passages formed by channels or grooves extending along the interface of the second surface of the distributor body with the inner wall of the distributor manifold.