A method for controlling ejector capacity in a vapour compression system
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Vapour compression systems face inefficiencies in managing ejector capacity and refrigerant flow, particularly in distributing capacity among different types of ejectors to optimize energy efficiency and handle liquid refrigerant flow effectively.
Innovation Solution
A method that adjusts ejector capacity based on parameter values representing liquid refrigerant flow rates and operating conditions, shifting between low and high pressure ejectors to match system requirements and ensure efficient operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If liquid ejectors are used to handle liquid refrigerant flow, then the pressure difference between primary inlet and outlet is small, but the pressure lift capability is high
Solution Approach 1:
The system dynamically switches between liquid ejectors and gas ejectors based on real-time operating conditions. The controller monitors parameters such as refrigerant flow rate, pressure, and temperature to determine when to activate each ejector type, optimizing energy efficiency across varying system demands
Solution Approach 2:
The invention changes the operational parameters by switching between different ejector types (liquid vs. gas) with distinct pressure-lift characteristics. Liquid ejectors operate with small pressure differences when high pressure lift is needed, while gas ejectors operate with larger pressure differences when energy efficiency is prioritized
2Loss of energy
If gas ejectors are used to provide high pressure lift, then larger pressure difference is required, but energy efficiency is high
Solution Approach 1:
The system dynamically switches between liquid ejectors and gas ejectors based on real-time operating conditions. The controller monitors parameters such as refrigerant flow rate, pressure, and temperature to determine when to activate each ejector type, optimizing energy efficiency across varying system demands
Solution Approach 2:
The invention changes the operational parameters by switching between different ejector types (liquid vs. gas) with distinct pressure-lift characteristics. Liquid ejectors operate with small pressure differences when high pressure lift is needed, while gas ejectors operate with larger pressure differences when energy efficiency is prioritized
3Productivity
If ejector capacity is increased to handle liquid refrigerant removal, then liquid refrigerant can be removed from return pipe, but power consumption increases
Solution Approach 1:
The system dynamically switches between liquid ejectors and gas ejectors based on real-time operating conditions. The controller monitors parameters such as refrigerant flow rate, pressure, and temperature to determine when to activate each ejector type, optimizing energy efficiency across varying system demands
Solution Approach 2:
The ejectors utilize the kinetic energy of the motive fluid (refrigerant) to create the suction effect needed to remove liquid refrigerant from the return pipe. The high-velocity motive fluid creates a low-pressure zone at the secondary inlet, automatically drawing in liquid refrigerant without requiring additional mechanical work or power input
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
This method enhances energy efficiency by optimizing ejector capacity distribution, effectively handling liquid refrigerant flow and ensuring that the most suitable type of ejector is used under prevailing conditions, thereby reducing power consumption and improving system performance.
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 (or secondary inlet) of the ejector by means of a motive fluid supplied to a motive inlet (or primary inlet) of the ejector
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A method for controlling ejector capacity in a vapour compression system (1) is disclosed. A parameter value being representative for a flow rate of liquid refrigerant from the evaporator(s) (8, 10) and into a return pipe (12, 13) is obtained, and the capacity of the ejector(s) (6) is adjusted based on the obtained parameter value. Ejector capacity may be shifted between low pressure ejectors (liquid ejectors) (6a, 6b, 6c, 6d) and high pressure ejectors (gas ejectors) (6e, 6f).