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 the capacity of 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 still achieving power consumption reduction benefits.
Solution Approach 2:
The control method changes the operational parameters of the ejector unit by adjusting its capacity based on measured pressure and temperature conditions. By varying the ejector capacity parameter in response to system state, the method optimizes the balance between power consumption reduction and maintaining adequate refrigerant pressure.
2Productivity
If the capacity of the ejector unit is increased to maximize refrigerant flow and reduce power consumption, then power consumption is reduced, but the pressure control becomes difficult to maintain
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 measured. Based on this feedback, the ejector capacity is automatically adjusted to maintain desired pressure levels while maximizing refrigerant flow through the ejector unit.
Solution Approach 2:
The patent replaces complex mechanical pressure control mechanisms with a control method that uses sensors and electronic control signals. The controller generates ejector control signals based on measured parameters, substituting automated electronic control for manual or purely mechanical pressure regulation systems.
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 pressure of refrigerant leaving the heat rejecting heat exchanger is maintained at an appropriate level, minimizing power consumption by optimizing the refrigerant flow through the ejector unit without risking a decrease in pressure, and is implemented in a simple and easy-to-control manner.
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
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.