A method for controlling a variable capacity ejector unit
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Solution Overview
Problem
Refrigeration systems with ejectors face challenges in maintaining a desired pressure level while minimizing power consumption, as the presence of an ejector can cause the pressure of refrigerant leaving the heat rejecting heat exchanger to decrease undesirably.
Innovation Solution
A method for controlling a variable capacity ejector unit in a refrigeration system by generating an ejector control signal based on the temperature and pressure of refrigerant leaving the heat rejecting heat exchanger, allowing for adjustments to the ejector unit's capacity to maintain an appropriate pressure level and maximize refrigerant flow, thereby reducing power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If an ejector is arranged in the refrigerant path to reduce power consumption, then power consumption is reduced, but the pressure of refrigerant leaving the heat rejecting heat exchanger decreases to an undesired low level
Solution Approach 1:
The ejector unit is designed with variable capacity, allowing the ejector's operation to be dynamically adjusted based on system conditions. The control method monitors the pressure of refrigerant leaving the heat rejecting heat exchanger and adjusts the ejector capacity accordingly, enabling the system to maintain desired pressure levels while utilizing the ejector's power-saving benefits when conditions permit.
Solution Approach 2:
The invention changes the operational parameters of the ejector by controlling its capacity variation. By adjusting the ejector's capacity based on measured pressure and temperature conditions, the system optimizes the balance between power consumption reduction and maintaining adequate refrigerant pressure in the high pressure part of the refrigeration system.
2Productivity
If the capacity of the ejector unit is increased to maximize refrigerant flow and power savings, then power consumption decreases, but the pressure level in the high pressure part of the system may drop below desired levels
Solution Approach 1:
The control method implements a feedback mechanism where the pressure and temperature of refrigerant leaving the heat rejecting heat exchanger are continuously monitored. Based on this feedback, the control method adjusts the ejector unit's capacity to maintain optimal system performance, ensuring that pressure levels remain adequate while maximizing the refrigerant flow through the ejector for power savings.
Solution Approach 2:
The ejector unit's capacity is made dynamically adjustable rather than fixed. The control method varies the ejector capacity based on real-time system conditions, allowing the system to adapt between maximizing refrigerant flow through the ejector and maintaining sufficient pressure levels in the high pressure part of the system.
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 method ensures that the refrigeration system maintains a desired pressure level while minimizing power consumption by optimizing the capacity of the ejector unit, ensuring that a large portion of refrigerant performs work without risking an undesirable pressure drop.
Implementation Method 1
An ejector is a type of pump which uses the Venturi effect to increase the pressure energy of fluid at a suction inlet of the ejector by means of a motive fluid supplied to a motive inlet of the ejector.
Data Source
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AI summary
A method for controlling a variable capacity ejector unit (7) arranged in a refrigeration system (1) is disclosed. An ejector control signal for the ejector unit (7) is generated, based on an obtained temperature and an obtained pressure of refrigerant leaving a heat rejecting heat exchanger (3), or on the basis of a high pressure valve control signal for controlling an opening degree of a high pressure valve (6) arranged fluidly in parallel with the ejector unit (7). The ejector control signal indicates whether the capacity of the ejector unit (7) should be increased, decreased or maintained. The capacity of the ejector unit (7) is controlled in accordance with the generated ejector control signal. The power consumption of the refrigeration system (1) is reduced, while the pressure of the refrigerant leaving the heat rejecting heat exchanger (3) is maintained at an acceptable level.