Ejector Mixing Passage Configuration to Limit Volume Growth
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Solution Overview
Problem
Ejectors in vapor compression refrigeration cycles face challenges in maintaining efficiency and compact size due to the configuration of refrigerant passages, leading to reduced pressure increase and increased volume, especially when the mixing passage is on the outer peripheral side of the passage formation member.
Innovation Solution
The ejector design incorporates a conical passage formation member with a shape that increases in cross-sectional area, limiting the axial growth of the diffuser passage and ensuring the mixing passage has a constant or gradually reduced cross-sectional area, preventing droplet adherence and enhancing the mixing of ejection and suction refrigerants.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the mixing passage is disposed on the outer peripheral side of the passage formation member, then the ejector efficiency is improved, but the ejector volume increases
Solution Approach 1:
The patent positions the mixing passage on the outer peripheral side of the passage formation member rather than along the axial direction, utilizing the radial dimension to improve mixing efficiency without significantly increasing the overall ejector volume. This spatial reconfiguration allows the mixing passage to be disposed in a different dimensional orientation, achieving better performance within the same volume constraints.
2Productivity
If the diffuser portion has a relatively small spread angle, then the ejector efficiency is improved, but the axial length of the nozzle portion increases
Solution Approach 1:
The patent reduces the spread angle of the diffuser portion to improve ejector efficiency while compensating for the increased axial length by reconfiguring the mixing passage in the radial direction. This allows the diffuser to be more compact axially when combined with the radially disposed mixing passage, achieving both improved efficiency and controlled length.
Solution Approach 2:
The patent combines the diffuser portion and mixing passage into an integrated structure where the mixing passage is disposed on the outer peripheral side of the passage formation member. This merging allows the two components to share space and function together, reducing the overall axial length requirement while maintaining the benefits of a small spread angle diffuser.
3Productivity
If a two-stage nozzle is used to depressurize refrigerant, then the nozzle efficiency is improved, but the device complexity increases
Solution Approach 1:
The patent implements a two-stage nozzle structure with a first nozzle and a second nozzle arranged in series along the refrigerant flow direction. The first nozzle depressurizes the refrigerant to an intermediate pressure, and the second nozzle further depressurizes it to the final low pressure. This segmentation of the depressurization process into two stages improves nozzle efficiency by reducing shock losses and improving expansion control, while the modular design keeps the added complexity manageable.
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 configuration restricts the increase in ejector volume, maintains high kinetic energy conversion to pressure energy, and limits efficiency reduction, even when the mixing passage is on the outer peripheral side, ensuring effective mixing and efficient operation.
Implementation Method 1
a nozzle passage, which functions as a nozzle that depressurizes and ejects the refrigerant
Implementation Method 2
a diffuser passage, which functions as a diffuser that converts a kinetic energy of mixed refrigerants into a pressure energy
Implementation Method 3
draws the fluid by a suction action of an ejection fluid ejected at high speed
Data Source
AI summary
In an ejector, a passage formation member is disposed inside a body forming a space therein. Provided between an inner peripheral surface of the body and the passage formation member are a nozzle passage functioning as a nozzle, a mixing passage in which an ejection refrigerant ejected from the nozzle passage and a suction refrigerant drawn through a suction passage are mixed together, and a diffuser passage that converts a kinetic energy of the refrigerant that has flowed out of the mixing passage into a pressure energy. The mixing passage has a shape gradually reducing in cross-sectional area toward a downstream side in the refrigerant flow.