System and method for detection and correction of reverse flow in an ejector refrigeration circuit

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Solution Overview

Problem

Reverse flow in ejector refrigeration circuits leads to significant losses in compressor efficiency, necessitating a system for detection and correction to maintain optimal operation.

Innovation Solution

A system comprising sensors and a controller that measure superheat differences across ejectors, identify reverse flow affected components, and adjust opening percentages to enhance refrigerant flow rates, thereby correcting reverse flow and maintaining efficient operation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If ejectors are operated in the refrigeration circuit, then compressor efficiency is improved by utilizing high pressure to compress low pressure gas, but reverse flow of refrigerant back to the secondary low pressure inlet causes large loss of compressor efficiency

Engineering Contradiction:

Improvecompressor efficiencyVSAvoidreverse flow detection

Core Design Contradiction:

Loss of energyVSReliability

Solution Approach 1:

The system implements feedback control by continuously monitoring superheat at the ejector suction port and comparing it with the evaporator outlet superheat. When reverse flow is detected through superheat difference analysis, the controller adjusts the expansion valve opening to correct the flow direction, ensuring stable compressor operation and preventing efficiency losses

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent replaces traditional mechanical reverse flow prevention mechanisms with a sensor-based detection system. By using temperature sensors to measure superheat and a controller to analyze the superheat difference, the system substitutes mechanical complexity with electronic monitoring and control, achieving more precise and reliable reverse flow detection

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Reliability

If reverse flow detection system is implemented, then reverse flow can be detected, but system complexity increases due to additional sensors and control mechanisms

Engineering Contradiction:

Improvereverse flow detection accuracyVSAvoiddetection system complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The detection system utilizes the existing temperature sensors already present in the refrigeration circuit for other monitoring purposes. By making these sensors serve the dual function of both temperature monitoring and reverse flow detection, the system achieves reliable reverse flow detection without adding dedicated sensors, thus minimizing the increase in system complexity

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The system uses the refrigerant's own thermal properties (superheat) as the detection medium. By measuring the natural superheat difference that occurs during reverse flow without requiring additional detection media or complex measurement mechanisms, the system achieves accurate detection while maintaining simplicity

Inventive Principle:

Principle #25Self-service

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 detects and corrects reverse flow, minimizing efficiency losses and maintaining consistent motive flow and high pressure within the refrigeration circuit, optimizing overall performance.

Implementation Method 1

Each of the plurality of first sensors is adapted to measure an ejector suction superheat of a refrigerant at the secondary low pressure input port of a corresponding ejector

Methodology Applied

Scientific EffectSuperheat measurement:

Implementation Method 2

The controller increases the opening percentage of the first ejector and reduces the opening percentage of the second ejector to increase a refrigerant flow rate of the first ejector

Methodology Applied

Scientific EffectFluid flow control:

Implementation Method 3

The ejectors improve efficiency in the refrigeration system by utilizing a high pressure to help compress a low pressure gas

Methodology Applied

Scientific EffectEjector compression: Jet

Data Source

PatentEP4484860A1System and method for detection and correction of reverse flow in an ejector refrigeration circuit

Publication Date: 2025.01.01 CARRIER CORP

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Figure 2A
Figure 2B

AI summary

A system (100) for detection and correction of reverse flow in an ejector refrigeration circuit, includes ejectors (101), first sensors (102) for measuring an ejector suction superheat of a refrigerant at a secondary low pressure input port (101b) of each of the ejectors (101), and a second sensor (103) for measuring a superheat of the refrigerant upstream relative to the secondary low pressure input port (101b). A controller (104) receives the ejector suction superheats and the refrigerant superheat and determines whether a superheat difference between each of the ejector suction superheats and the refrigerant superheat falls below a threshold superheat difference. The controller (104) identifies a first ejector (101') as a reverse flow affected ejector based on the determined superheat difference. The controller (104) compares opening percentages of the ejectors to determine a second ejector (101") having the largest opening percentage and controls the first ejector (101') and the second ejector (101") to increase a refrigerant flow rate of the first ejector (101').