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 increases energy consumption.
Innovation Solution
A map-interpolation based control system that uses a controller to generate maps associated with different temperatures of a heat rejecting heat exchanger, predicting the opening percentage of ejectors through linear interpolation, and adjusting these settings to prevent reverse flow and optimize performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If ejectors are operated to improve compressor efficiency, then energy consumption is reduced, but reverse flow occurs causing loss of compressor efficiency
Solution Approach 1:
The control system performs preliminary actions by generating multiple maps associated with different temperatures of the heat rejecting heat exchanger before operation. These maps contain pre-calculated opening percentages that prevent reverse flow conditions from occurring in the first place, rather than reacting after reverse flow has started
Solution Approach 2:
The system continuously monitors the actual temperature of the heat rejecting heat exchanger and uses this feedback to identify the appropriate map and select the correct opening percentage for the ejectors. This closed-loop feedback ensures the ejectors operate in conditions that prevent reverse flow while maintaining energy efficiency
2Productivity
If ejector opening percentage is increased to handle higher flow rates, then refrigeration capacity is improved, but reverse flow is more likely to occur
Solution Approach 1:
The system applies local quality by creating different maps with different opening percentage recommendations for different operating conditions (temperatures). Instead of using a single uniform control strategy, the control system selects the appropriate local opening percentage from the relevant map based on current temperature conditions, preventing reverse flow while maximizing capacity
Solution Approach 2:
The invention changes the control parameter from a fixed opening percentage to a variable opening percentage that depends on the temperature parameter of the heat rejecting heat exchanger. By dynamically adjusting the opening percentage based on temperature conditions, the system prevents reverse flow while maintaining optimal refrigeration capacity
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 effectively prevents reverse flow in ejectors, enhancing compressor efficiency and reducing energy consumption by optimizing the opening percentages of ejectors based on real-time temperature and flow rate conditions.
Implementation Method 1
The step of predicting the opening percentage includes identifying a first opening percentage from the plurality of opening percentages indicated in the first map and a second opening percentage from the plurality of opening percentages indicated in the second map. Then, the step includes performing a linear interpolation to fit a line between the identified first opening percentage and the identified second opening percentage.
Implementation Method 2
The ejectors improve efficiency in the refrigeration system by utilizing a high pressure to help compress a low pressure gas, instead of relying solely on a compressor.
Implementation Method 3
Each of the plurality of maps is associated with a corresponding temperature of a heat rejecting heat exchanger
Data Source
AI summary
A system for map-interpolation based control of ejectors in an ejector refrigeration circuit includes a controller coupled to each of the ejectors and adapted to generate maps based on predefined conditions. The controller identifies a first map associated with a first temperature of a heat rejecting heat exchanger and a second map 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.