A method for fault tolerant control of a vapour compression system
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Solution Overview
Problem
Vapour compression systems face challenges in obtaining reliable ambient temperature measurements due to solar heating of ambient temperature sensors, leading to non-optimal operation and increased energy consumption.
Innovation Solution
A method that selects a time period when the ambient temperature sensor is unexposed to solar heating, allowing for reliable measurements to be obtained. These measurements are then used to derive model parameters that correlate ambient temperature with other system parameters, enabling the system to operate optimally even when the sensor is exposed to solar heating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the ambient temperature sensor is positioned in direct sunlight or near solar-heated surfaces, then the sensor can be easily installed and accessed, but the sensor measurements become faulty indicating ambient temperature above actual ambient temperature
Solution Approach 1:
The system performs preliminary calibration during a selected time period when the sensor is unexposed to solar heating, establishing accurate model parameters before the sensor becomes faulty. This preliminary action allows the system to later compensate for solar heating effects even when the sensor is exposed to sunlight during operation.
Solution Approach 2:
The system changes the operational parameters by selecting specific time periods for calibration when solar heating is absent, and uses derived model parameters to adjust and correct temperature readings during periods when the sensor is exposed to solar heating, thereby maintaining measurement accuracy despite environmental conditions.
2Productivity
If the ambient temperature sensor is exposed to solar heating, then the sensor remains continuously operational, but the measurements become non-optimal leading to non-optimal system operation and increased energy consumption
Solution Approach 1:
The system uses feedback from the derived model parameters to continuously correct and adjust the ambient temperature readings. By comparing actual sensor measurements against the model predictions during operation, the system can identify and compensate for solar heating effects, maintaining reliable measurements throughout continuous operation.
Solution Approach 2:
The patent introduces an intermediary mathematical model that mediates between the faulty sensor measurements and the control system. This model acts as a translator, converting the unreliable raw sensor data into accurate ambient temperature information that can be used for optimal system operation.
3Extent of automation
If the system uses ambient temperature measurements for calculating setpoint values, then the system can be controlled efficiently, but faulty measurements lead to non-optimal setpoint values and non-optimal operation
Solution Approach 1:
The system performs preliminary calibration during a selected time period when the sensor is unexposed to solar heating, establishing accurate model parameters before the sensor becomes faulty. This preliminary action allows the system to later compensate for solar heating effects even when the sensor is exposed to sunlight during operation.
Solution Approach 2:
The system uses feedback from the derived model parameters to continuously correct and adjust the ambient temperature readings. By comparing actual sensor measurements against the model predictions during operation, the system can identify and compensate for solar heating effects, maintaining reliable measurements throughout continuous operation.
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
Ensures reliable operation of vapour compression systems by providing accurate ambient temperature values, even under conditions where the sensor is faulty due to solar heating, thereby maintaining optimal performance and energy efficiency.
Implementation Method 1
an ambient temperature sensor arranged to measure an ambient temperature
Implementation Method 2
If the ambient temperature sensor is positioned in direct sunlight, or near a surface which is heated by solar radiation
Implementation Method 3
there is a risk that the ambient temperature sensor is heated
Data Source
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AI summary
A method for controlling a vapour compression system (1) is disclosed, the vapour compression system (1) comprising an ambient temperature sensor (8) arranged to measure an ambient temperature. A time period during which the ambient temperature sensor (8) is unexposed to solar heating is selected. During the selected time period, measurements of the ambient temperature are obtained by means of the ambient temperature sensor (8), and measurements of at least one further parameter related to the vapour compression system (1) are obtained, while operating the vapour compression system (1). Model parameters for a model of at least a part of the vapour compression system (1) are derived, based on the obtained measurements, the model providing correlation between the ambient temperature and the at least one further parameter. Subsequently, the vapour compression system (1) is operated based on measurements of the at least one further parameter and based on ambient temperatures derived by means of the model including the derived model parameters.