Ejector system and methods of operation
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Solution Overview
Problem
Ejector refrigeration systems face inefficiencies at normal operating conditions due to ejectors being sized for maximum flow rates, leading to suboptimal performance and potential damage from high pressures, necessitating a solution to manage pressure and improve efficiency.
Innovation Solution
Incorporating a bypass flowpath that bypasses the ejector motive nozzle and rejoins the primary flowpath upstream of the separator, with a control system to manage flow and pressure, allowing for unloading of the ejector and optimizing performance by varying the fraction of flow through the bypass path based on sensed pressures and temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the ejector is sized for maximum flow rates, then it can handle peak pressure conditions, but it operates suboptimally at normal operating conditions
Solution Approach 1:
The ejector system incorporates a movable control needle that can adjust the flow area dynamically. The needle moves between a first position (normal operation) and a second position (pressure relief), allowing the system to adapt its characteristics to match different operating conditions rather than being fixed for maximum flow rates only
Solution Approach 2:
The control needle changes the effective flow parameters of the ejector by adjusting its position. This modifies the flow area and pressure characteristics, enabling the ejector to operate efficiently at normal conditions while still handling peak pressures when needed
2Object-affected harmful factors
If the ejector is sized for maximum flow rates, then it can relieve high pressures, but efficiency is reduced at normal conditions
Solution Approach 1:
The control needle provides partial action by opening only as much as needed to relieve pressure. Instead of fully opening the pressure relief path, the needle can be positioned to provide just enough relief to maintain safe operating conditions, minimizing energy loss while still protecting against high pressure damage
3Reliability
If a bypass flowpath is added to unload the ejector, then pressure management is improved, but device complexity increases
Solution Approach 1:
The bypass flowpath serves multiple functions: it provides pressure relief when needed, allows the ejector to operate at optimal efficiency during normal conditions, and can be integrated with existing system components. The control needle mechanism also serves dual purposes by controlling both the pressure relief and the flow distribution
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 enhances efficiency by allowing the ejector to operate more efficiently at normal conditions, reduces the risk of damage from high pressures, and improves heat transfer performance by stabilizing flow conditions entering the separator.
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 of the motive nozzle. The motive nozzle accelerates the flow and decreases the pressure of the flow.
Implementation Method 2
Upon entering the separator, the flow is separated back into the flows and . The flow passes as a gas through the compressor suction line as discussed above. The flow passes as a liquid to the expansion valve.
Data Source
Figure 1~2
Figure 3~3A
Figure 4
AI summary
A vapor compression system (200; 300; 400) comprising: a compressor (22); a first heat exchanger (30); a second heat exchanger (64); an ejector (38); separator (48); and an expansion device (70). A plurality of conduits are positioned to define a first flowpath sequentially through: the compressor; the first heat exchanger; the ejector from a motive flow inlet through (40) an outlet (44); and the separator, and then branching into: a first branch returning to the compressor; and a second branch passing through the expansion device and second heat exchanger to a secondary flow inlet (42). The plurality of conduits are positioned to define a bypass flowpath (202; 302; 402) bypassing the motive flow inlet and rejoining the first flowpath at essentially separator pressure but away from the separator.