Vapour Compression System Control During Gas Bypass Valve Malfunction
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Solution Overview
Problem
Vapour compression systems, such as refrigeration and heat pump systems, often malfunction due to a stuck gas bypass valve, leading to instability and the inability to provide required cooling or heating capacity, resulting in costly shutdowns.
Innovation Solution
A method to control the vapour compression system by registering and comparing the actual opening degree of the gas bypass valve to a target opening degree, adjusting the mass flow of gaseous refrigerant to match the actual capacity, thereby allowing continued operation despite valve malfunction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the gas bypass valve is controlled to provide required cooling or heating capacity, then the system can meet system requirements and adapt to ambient conditions, but the system becomes unstable or incapable of providing required capacity when the valve malfunctions and is stuck
Solution Approach 1:
The control method continuously monitors the actual opening degree of the gas bypass valve and compares it to the target opening degree. When a malfunction is detected (actual opening degree differs from target), the system adjusts other parameters to compensate and maintain stability. This closed-loop feedback mechanism allows the system to adapt to the malfunctioned valve position while maintaining reliable operation.
Solution Approach 2:
When the gas bypass valve is stuck at an incorrect opening degree, the control method changes other system parameters (such as compressor speed, expansion valve opening degree, or heat exchanger parameters) to compensate for the valve malfunction. This parameter adjustment allows the system to maintain required cooling or heating capacity despite the valve being stuck, thereby maintaining both adaptability and reliability.
2Productivity
If the vapour compression system continues operating with a malfunctioning gas bypass valve, then operational continuity is maintained, but the system becomes unstable and may shut down
Solution Approach 1:
The control method implements continuous monitoring of the gas bypass valve opening degree and system performance parameters. When instability is detected or the valve malfunction is identified, the system immediately adjusts operating parameters to restore stability, allowing continuous operation without shutdown while maintaining reliability.
Solution Approach 2:
The control method detects valve malfunction and compensates for it before system instability occurs. By proactively adjusting other parameters when a valve sticking is detected, the system prevents instability and shutdown events, ensuring both operational continuity and reliability.
3Productivity
If the gas bypass valve opening degree is varied to meet system requirements, then cooling or heating capacity is provided, but the malfunctioning valve stuck at a fixed position cannot match the desired opening degree
Solution Approach 1:
When the gas bypass valve is stuck at a fixed opening degree that does not match the desired position, the control method changes other system parameters (such as compressor capacity, expansion device opening degree, or heat exchanger parameters) to achieve the required cooling or heating capacity. This compensatory parameter adjustment maintains productivity while adapting to the valve's fixed position.
Solution Approach 2:
The control method continuously compares the actual valve opening degree with the target opening degree and uses feedback to adjust other system parameters. This ensures that the required cooling or heating capacity is maintained despite the valve being stuck, preserving both productivity and adaptability.
Data Source
AI summary
A method for controlling a vapour compression system (1) is disclosed. Malfunctioning of a gas bypass valve (8) is registered. An actual opening degree of the gas bypass valve (8) is derived, and a target opening degree of the gas bypass valve (8) is derived, based on one or more control parameters of the vapour compression system (1). The actual opening degree is compared to the target opening degree, and the vapour compression system (1) is controlled based on the comparison, and in order to match a mass flow of gaseous refrigerant through the gas bypass valve (8) to the actual opening degree of the gas bypass valve (8).