System and method for map-interpolation based control of ejectors in an ejector refrigeration circuit
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Solution Overview
Problem
Existing control systems for ejector refrigeration circuits face efficiency losses due to reverse flow, which reduces compressor efficiency and energy usage.
Innovation Solution
A map-interpolation based control system for ejectors, where a controller generates maps based on predefined conditions and temperatures, predicts the opening percentage of each ejector through interpolation, and adjusts it to optimize performance and prevent reverse flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If existing control systems dynamically control the ejectors, then the ejectors can operate in the refrigeration circuit, but reverse flow occurs causing large loss of compressor efficiency
Solution Approach 1:
The control system performs preliminary actions by generating multiple pre-calculated maps showing optimal ejector opening percentages for different heat rejecting heat exchanger temperatures and refrigerant flow rates. Before operating conditions cause reverse flow, the system has already determined the appropriate corrective ejector opening from the pre-generated maps, allowing preventive control rather than reactive control.
Solution Approach 2:
The system continuously monitors the heat rejecting heat exchanger temperature and refrigerant flow rate, compares current conditions against the pre-generated maps, and dynamically adjusts ejector opening percentages based on this feedback. This closed-loop control ensures the ejectors operate optimally across varying conditions while preventing reverse flow that would reduce compressor efficiency.
2Ease of operation
If the high pressure fluid and outlet fluid flow back to the secondary low pressure inlet, then the ejector continues to operate, but a large loss of compressor efficiency results
Solution Approach 1:
The system generates multiple maps in advance that show the optimal opening percentage for each ejector under various operating conditions (different heat rejecting heat exchanger temperatures and refrigerant flow rates). These pre-calculated maps enable the control system to determine the correct ejector opening before reverse flow occurs, allowing continuous operation while preventing efficiency loss.
Solution Approach 2:
The control system dynamically changes the opening percentage parameter of the ejectors based on real-time monitoring of heat rejecting heat exchanger temperature and refrigerant flow rate. By adjusting this key parameter according to pre-generated maps, the system maintains optimal operation across varying conditions and prevents the high pressure and outlet fluids from flowing back to the secondary low pressure inlet.
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
The system enhances machine performance by optimizing ejector operation, reducing energy consumption, and minimizing reverse flow, thereby improving overall compressor efficiency.
Implementation Method 1
the ejectors improve efficiency in the refrigeration system by utilizing a high pressure to help compress a low pressure gas
Implementation Method 2
The ejectors include a primary high pressure inlet, a secondary low pressure inlet, and an outlet. When an ejector is used as part of the refrigeration system, the cooled refrigerant from the heat rejecting heat exchanger enters each of the ejectors at the high pressure inlet and is expanded to a lower pressure at the outlet of each of the ejectors.
Implementation Method 3
Each of the plurality of maps is associated with a corresponding temperature of a heat rejecting heat exchanger
Data Source
Figure 1A
Figure 1B
Figure 2A
AI summary
A system (101) for map-interpolation based control of ejectors (101) in an ejector refrigeration circuit includes a controller (104) coupled to each of the ejectors and adapted to generate maps (200, 200A, 200B, 200C) based on predefined conditions. The controller identifies a first map (200A) associated with a first temperature of a heat rejecting heat exchanger (105) and a second map (200B) associated with a second temperature of the heat rejecting heat exchanger. The controller predicts an opening percentage of the first ejector from at least one of opening percentages indicated in the first map and opening percentages indicated in the second map. Finally, the controller adjusts the opening percentage of the first ejector based on the predicted opening percentage.