Variable-Exit Ejector Nozzle for Overexpansion Loss 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 associated losses in refrigeration efficiency, particularly when the throat area is reduced, resulting in up to 20% loss in efficiency.
Innovation Solution
The introduction of a mechanism to vary the effective area of the exit of the motive nozzle, in addition to controlling the throat area, using a needle that moves along a range of motion to adjust the area ratio, thereby compensating for the inefficiencies caused by throat area reduction and maintaining optimal expansion ratios for efficient refrigeration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the throat area of the motive nozzle is reduced to control high-side pressure, then the compressor power consumption is reduced, but the refrigeration efficiency is reduced by up to 20%
Solution Approach 1:
The patent applies the dynamics principle by making the nozzle geometry adjustable through a needle valve mechanism. The needle valve can dynamically modify both the throat area and exit area of the motive nozzle, allowing the system to adapt to varying operating conditions. This dynamic adjustment enables optimization of the area ratio to maintain efficient refrigeration cycles while controlling compressor power consumption.
Solution Approach 2:
The patent implements parameter changes by modifying the physical dimensions of the nozzle - specifically the throat area and exit area. By changing these geometric parameters through needle valve adjustment, the system can control the expansion ratio and area ratio of the refrigerant flow. This allows optimization of the refrigeration cycle efficiency while managing the compressor power requirements.
2Use of energy by moving object
If the area ratio of the nozzle is large, then the expansion is enhanced, but overexpansion occurs leading to efficiency losses
Solution Approach 1:
The patent uses the dynamics principle to make the nozzle area ratio adjustable. The needle valve mechanism allows dynamic modification of both throat and exit areas, enabling the system to maintain an optimal area ratio that prevents overexpansion while still achieving sufficient expansion for efficient refrigeration. This dynamic control adapts to varying system conditions to avoid energy losses.
Solution Approach 2:
The patent applies parameter changes by modifying the geometric parameters of the nozzle - specifically adjusting the relationship between throat area and exit area. By changing these dimensions through needle valve control, the system optimizes the area ratio to achieve efficient expansion without overexpansion, thereby maximizing energy utilization while minimizing losses.
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 approach allows for partial compensation of efficiency losses by adjusting the exit area, optimizing the expansion ratio and maintaining high efficiency in refrigeration systems, particularly in transcritical cycles, by reducing the high-side pressure and enhancing cooling capacity while minimizing compressor power consumption.
Implementation Method 1
The motive nozzle accelerates the flow and decreases the pressure of the flow
Implementation Method 2
The resulting combined flow is a liquid/vapor mixture and decelerates and recovers pressure in the diffuser
Data Source
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).