Variable-Area Ejector Nozzle for Overexpansion Control
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Solution Overview
Problem
Ejector refrigeration systems face inefficiencies due to large area ratios in controllable nozzles leading to overexpansion and loss of efficiency, particularly when the throat area is reduced, resulting in reduced refrigeration effect and increased power consumption.
Innovation Solution
The introduction of a controllable ejector design with a variable effective area at the exit of the motive nozzle, using a needle valve to adjust the area ratio, allowing for partial compensation of throat area reductions and maintaining optimal expansion ratios for efficient refrigeration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If the throat area of the motive nozzle is reduced to control high-side pressure, then the high-side pressure is reduced, but the area ratio increases causing overexpansion and loss of refrigeration effect
Solution Approach 1:
The patent applies dynamics by making the nozzle geometry adjustable through a needle valve that can vary the throat area and exit area independently. This allows the system to adapt the area ratio dynamically to match operating conditions, preventing overexpansion losses while maintaining pressure control.
Solution Approach 2:
The patent changes physical parameters by introducing a controllable variable area ratio through the needle valve mechanism. By independently adjusting throat area and exit area, the system optimizes the area ratio parameter to prevent overexpansion while maintaining the desired high-side pressure, thereby resolving the contradiction between pressure control and refrigeration effect.
2Stress or pressure
If the area ratio of the motive nozzle is increased to reduce high-side pressure, then the pressure control is improved, but the expansion ratio becomes too high causing overexpansion and efficiency loss
Solution Approach 1:
The needle valve mechanism enables dynamic adjustment of the nozzle geometry, allowing the area ratio to be optimized in real-time based on operating conditions. This dynamic control prevents overexpansion while maintaining effective pressure control, thereby preserving system efficiency.
Solution Approach 2:
The patent introduces a controllable area ratio parameter through the needle valve, allowing independent variation of throat and exit areas. This parameter change enables the system to maintain optimal expansion ratios across different operating conditions, resolving the contradiction between pressure control capability and system efficiency.
3Device complexity
If a fixed geometry ejector is used, then the device complexity is low, but the system cannot adapt to varying operating conditions leading to suboptimal performance
Solution Approach 1:
The patent transforms the fixed geometry ejector into a dynamic system by incorporating a needle valve that can adjust the throat and exit areas. This adds adaptability to varying operating conditions while maintaining relatively simple device complexity through the use of a single adjustable component.
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 design enhances the efficiency of the ejector refrigeration system by reducing energy losses associated with overexpansion, optimizing refrigeration effect, and minimizing power consumption, while allowing for adaptable operation across varying conditions.
Implementation Method 1
The primary refrigerant flow enters the inlet and then passes into a convergent section of the motive nozzle. It then passes through a throat section and an expansion (divergent) section through an outlet (exit) of the motive nozzle. The motive nozzle accelerates the flow and decreases the pressure of the flow.
Implementation Method 2
The pressure reduction caused to the primary flow by the motive nozzle helps draw the secondary flow into the outer member.
Implementation Method 3
The resulting combined flow is a liquid/vapor mixture and decelerates and recovers pressure in the diffuser while remaining a mixture.
Data Source
Figure 1~2
Figure 3~3A
Figure 4~4A
AI summary
An ejector (200; 300; 320; 340; 400; 430; 460; 480) has a primary inlet (40), a secondary inlet (42), and an outlet (44). A primary flowpath extends from the primary inlet (40) to the outlet (44) and a secondary flowpath extends from the secondary inlet (42) to the outlet (44), merging with the primary flowpath. A motive nozzle (100) surrounds the primary flowpath upstream of a junction with the secondary flowpath. The motive nozzle (100) has a throat (106) and an exit (110). The ejector (200; 300; 320; 340; 400; 430; 460; 480) further has a means (204, 210; 304; 322; 342; 402; 432; 462; 482) for varying an effective area of the exit (110) or simultaneously varying the effective area of the exit (110) and an effective area of the throat (106).