Packed-Manifold Heat Exchanger for Stable Two-Phase Flow
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Solution Overview
Problem
Conventional heat exchangers, particularly in low-temperature and cryogenic refrigeration systems, face inefficiencies due to poor phase distribution in two-phase flow environments, leading to reduced heat transfer coefficients, increased pressure drop, and freeze-out conditions, especially in compact designs like plate-type heat exchangers.
Innovation Solution
A heat exchanger design incorporating a packed distributor within the manifold, utilizing various packing elements such as spherical balls, ellipsoidal, or ring elements, to improve flow distribution and reduce pressure drop, while maintaining a high heat transfer coefficient, specifically optimized for refrigeration systems operating below 200K.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If plate type heat exchangers are used to achieve better surface area to volume ratio and compactness, then the heat exchanger becomes more compact, but phase distribution becomes poor leading to reduced heat transfer coefficients and increased pressure drop
Solution Approach 1:
A packed distributor is introduced as an intermediary component within the manifold of the plate type heat exchanger. This distributor, filled with packing elements, acts as a mediator to improve two-phase flow distribution into the heat transfer channels, thereby resolving the poor phase distribution issue while maintaining the compact plate type design
Solution Approach 2:
The packed distributor utilizes porous packing elements (such as random packing or structured elements) that allow fluid to pass through while promoting better phase distribution. The porous structure of the packing elements helps to evenly distribute two-phase flow into the heat transfer channels, addressing the distribution problems in compact plate type heat exchangers
2Reliability
If conventional distributors are used in plate type heat exchangers to improve phase distribution, then heat transfer coefficient improves, but pressure drop increases significantly (greater than 18 psi)
Solution Approach 1:
The invention changes the physical parameters of the distributor by using packed elements with specific size ranges (0.5-2 inches for random packing, or structured elements with controlled geometry). This parameter optimization allows achieving good phase distribution while limiting pressure drop to no more than 5 psi, significantly lower than conventional distributors
3Stress or pressure
If tubular heat exchangers are used to achieve low pressure drop and inexpensive construction, then pressure drop decreases and cost reduces, but surface area per unit volume becomes low requiring long tubing extensions
Solution Approach 1:
The invention transitions from the tubular geometry (one-dimensional flow path) to a plate type geometry with packed distributor (multi-dimensional flow distribution). This dimensional change allows achieving both compactness with high surface area density and low pressure drop through the optimized packed distributor design
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 packed distributor design achieves a pressure drop of no more than 5 psi and enhances the overall heat transfer coefficient by at least 2%, improving system efficiency and stability across different operating modes, including cool, standby, and defrost modes.
Implementation Method 1
A fluid entering the fluid inlet manifold may comprise at least two phases, which may be vapor and liquid
Implementation Method 2
a plurality of heat transfer channels configured to communicate with the fluid inlet manifold and the fluid outlet manifold
Data Source
AI summary
Aspects of the invention are found in a heat exchanger. The heat exchanger includes a fluid inlet manifold, a fluid outlet manifold, a plurality of heat transfer channels configured to communicate with the fluid inlet manifold and the fluid outlet manifold, and packing located within the fluid inlet manifold. Further aspects of the invention are found in a refrigeration system. The refrigeration system includes a compressor and at least one heat exchanger coupled to the compressor. The at least one heat exchanger includes a header, packing located in the header, and a heat transfer channel. The heat transfer channel is configured to receive fluid passing through the header and the packing.