Method for handling fault mitigation in a vapour compression system
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Solution Overview
Problem
Vapour compression systems, such as refrigeration and heat pump systems, face inefficiencies and instability when a sensor malfunctions, leading to potential shutdowns and increased energy consumption, as existing methods do not ensure optimal energy-efficient operation without direct sensor input.
Innovation Solution
A method that estimates the mass flow of gaseous refrigerant using some operational sensors and derives refrigerant pressure or temperature values, allowing the system to operate reliably even with malfunctioning sensors, by using calculations, look-up tables, or models, and comparing derived values with actual measurements to evaluate sensor reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the vapour compression system continues operating with a malfunctioning sensor, then system availability is improved, but energy efficiency deteriorates and system stability worsens
Solution Approach 1:
The patent introduces an intermediary estimation mechanism that uses mathematical models and available sensor data to infer the state of malfunctioning sensors. This intermediary layer allows the system to continue operating with acceptable energy efficiency by compensating for missing sensor inputs through calculated estimates rather than direct measurements.
Solution Approach 2:
The patent creates a virtual copy of the malfunctioning sensor's function by using mathematical models to estimate what the sensor would read if it were working. This copied information allows the control system to maintain proper energy efficiency without relying on the actual malfunctioning sensor.
2Reliability
If the vapour compression system continues operating with a malfunctioning sensor, then system availability is improved, but system stability deteriorates
Solution Approach 1:
The patent implements feedback mechanisms where the estimated sensor values are continuously compared with actual measurements from working sensors. This feedback loop allows the system to detect inconsistencies and adjust operations to maintain stability, preventing the system from becoming unstable due to reliance on malfunctioning sensor data.
Solution Approach 2:
The patent employs dynamic adjustment of control parameters based on the estimated sensor values and system state. By continuously adapting control strategies according to real-time conditions and confidence levels in sensor data, the system maintains stability even when operating with incomplete or potentially inaccurate sensor information.
3Reliability
If traditional sensor fault handling methods are used, then system safety is improved, but device complexity increases
Solution Approach 1:
The patent creates a universal fault handling framework that can accommodate various types of sensor failures and system configurations through a single mathematical modeling approach. This multi-functional method reduces overall system complexity by providing a unified solution that works across different sensor types and failure modes, rather than requiring separate complex handling mechanisms for each scenario.
4Stability of the object's composition
If the vapour compression system shuts down immediately upon sensor malfunction, then system stability is improved, but productivity deteriorates
Solution Approach 1:
The patent prepares cushioning measures in advance by implementing mathematical models and estimation algorithms that can take over when sensors fail. This prior preparation allows the system to maintain stability and continue operating without immediate shutdown, thereby preserving productivity while ensuring system safety through pre-established fallback mechanisms.
Data Source
AI summary
A method for controlling a vapour compression system (1) is disclosed. A mass flow of refrigerant along a part of the refrigerant path is estimated, based on measurements performed by one or more pressure sensors (10, 12, 13) for measuring a refrigerant pressure at selected positions along the refrigerant path and one or more temperature sensors (11, 14) for measuring a refrigerant temperature at selected positions along the refrigerant path. A refrigerant pressure or a refrigerant temperature at a selected position a pressure sensor (10, 12, 13) or temperature sensor (11, 14) along the refrigerant path is derived, based on the estimated mass flow. The vapour compression system (1) is allowed to continue operating, even if a sensor (10, 11, 12, 13, 14) is malfunctioning or unreliable.