Variable-Nozzle Ejector for Changing Refrigeration Conditions
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Solution Overview
Problem
Conventional ejector refrigeration systems face inefficiencies due to changing operating conditions, which lead to increased friction and mixing losses, reducing pressure recoveries and system performance.
Innovation Solution
A controllable ejector design with a motive nozzle that can be dynamically shifted relative to the convergent section, using an actuator to optimize the position based on sensed operational parameters, thereby maximizing system efficiency and coefficient of performance (COP).
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the motive nozzle position is fixed in conventional ejectors, then the structure is simple, but the pressure recovery and system performance decrease under changing operating conditions due to increased friction and mixing losses
Solution Approach 1:
The patent applies the dynamics principle by making the motive nozzle position adjustable rather than fixed. The actuator mechanism enables the motive nozzle to move axially relative to the mixing section, allowing the ejector geometry to dynamically adapt to changing operating conditions. This dynamic adjustment optimizes the interaction between primary and secondary flows, reducing friction and mixing losses while maintaining structural feasibility through a controlled degree of freedom.
2Productivity
If the motive nozzle is dynamically adjusted, then pressure rise and system efficiency are optimized, but the device complexity and control requirements increase
Solution Approach 1:
The patent applies parameter changes by adjusting the geometric parameter of the motive nozzle position to optimize system performance. The actuator mechanism changes the axial position parameter of the motive nozzle relative to the mixing section, thereby modifying the flow interaction parameters. This allows the ejector to adapt to varying operating conditions and maintain optimal pressure rise and efficiency without requiring complete redesign of the system architecture.
Solution Approach 2:
The patent applies feedback control by using sensors to detect operating conditions and feeding this information back to the actuator mechanism. The controller processes the sensor signals and adjusts the motive nozzle position accordingly, creating a closed-loop control system. This feedback mechanism enables the ejector to automatically optimize its performance in response to changing operating conditions while maintaining manageable control complexity through automated regulation.
3Stress or pressure
If the motive nozzle position is optimized for specific conditions, then pressure recovery is maximized, but the ejector performance degrades when operating conditions change
Solution Approach 1:
The patent resolves this contradiction by implementing a dynamic adjustment mechanism that allows the motive nozzle position to change in response to varying operating conditions. Rather than being optimized for a single fixed condition, the actuator-enabled motive nozzle can continuously adapt its position to maintain optimal pressure recovery across a range of operating scenarios, thereby achieving both high pressure recovery and adaptability.
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 adaptive optimization of the ejector's performance, ensuring peak pressure rise and system efficiency by iteratively adjusting the motive nozzle position in response to changing conditions, thus enhancing the refrigeration system's overall performance and reducing energy consumption.
Implementation Method 1
The primary refrigerant flow 103 enters the inlet 40 and then passes into a convergent section 104 of the motive nozzle 100. It then passes through a throat section 106 and an expansion (divergent) section 108 through an outlet 110 of the motive nozzle 100. The motive nozzle 100 accelerates the flow 103 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 112 into the outer member.
Implementation Method 3
The outer member includes a mixer having a convergent section 114 and an elongate throat or mixing section 116. As the flow 103 exits the outlet 110, it begins to mix with the flow 112 with further mixing occurring through the mixing section 116 which provides a mixing zone.
Implementation Method 4
The outer member also has a divergent section or diffuser 118 downstream of the elongate throat or mixing section 116. The resulting combined flow 120 is a liquid/vapor mixture and decelerates and recovers pressure in the diffuser 118 while remaining a mixture.
Data Source
AI summary
An ejector has a primary inlet (40), a secondary inlet (42), and an outlet (44). A primary flowpath extends from the primary inlet to the outlet. A secondary flowpath extends from the secondary inlet to the outlet. A mixer convergent section (114; 300; 400) is downstream of the secondary inlet. A motive nozzle (100) surrounds the primary flowpath upstream of a junction with the secondary flowpath. The motive nozzle has a throat (106) and an exit (110). An actuator (204) is coupled to the motive nozzle to drive a relative streamwise shift of the exit and convergent section.