Multi-Gas Flow Rate Control with Primary Pressure Compensation
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Solution Overview
Problem
In multi-gas flow controllers, existing technologies fail to accurately control flow rates regardless of fluid types due to primary pressure fluctuations, leading to measurement errors.
Innovation Solution
A pressure insensitive flow rate control system that includes a flow rate sensor, a pressure sensor, a pressure insensitive calibration value determination unit, and a drive control circuit, which determines and applies a calibration value based on fluid physical properties to correct flow rate measurements and maintain a set flow rate value.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional flow rate controller is used, then the device structure is simple, but the flow rate measurement precision deteriorates due to primary pressure fluctuations
Solution Approach 1:
A pressure sensor is introduced as an intermediary component to measure primary pressure fluctuations. The measured pressure data is then used by a correction unit to compensate flow rate measurements, thereby eliminating the harmful effect of pressure variations without fundamentally changing the flow controller structure
Solution Approach 2:
The system changes the measurement parameters by introducing pressure as an additional measured variable. By measuring both pressure and flow rate, and then correcting the flow rate based on pressure data, the system achieves higher measurement precision while maintaining relatively simple device structure
2Measurement precision
If a pressure insensitive flow rate controller is introduced, then the flow rate measurement precision is improved, but the device complexity increases due to additional sensors and correction mechanisms
Solution Approach 1:
The pressure sensor and flow rate sensor are merged into a single control system with a unified correction mechanism. The correction unit integrates both measurement data streams and applies compensation together, reducing overall system complexity compared to having separate independent systems
Solution Approach 2:
A feedback mechanism is implemented where the pressure sensor continuously monitors primary pressure and feeds this information to the correction unit, which then adjusts the flow rate measurement in real-time. This closed-loop feedback approach achieves high precision without requiring complex open-loop compensation structures
3Adaptability or versatility
If the flow rate controller is designed for multi-gas application, then the adaptability is improved, but the measurement precision deteriorates due to varying physical properties of different fluids
Solution Approach 1:
The flow rate controller is designed with universal functionality to handle multiple gas types. The pressure correction mechanism serves all fluid types universally, applying the same correction principle regardless of the specific gas being measured, thereby maintaining precision across different applications
Solution Approach 2:
The system accounts for varying physical properties of different fluids by using pressure as a universal correction parameter. Since pressure effects are fundamental to all gases, the same pressure-based correction approach works universally across different gas types, maintaining measurement precision while achieving multi-gas adaptability
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 system accurately controls flow rates across different fluid types by compensating for pressure fluctuations, ensuring precise flow rate maintenance regardless of fluid types.
Implementation Method 1
a flow rate sensor measuring the flow rate of the fluid... (where the flow rate sensor may be a thermal mass flow sensor)
Implementation Method 2
a pressure sensor measuring a pressure of a primary side of the flow rate controller
Implementation Method 3
a correction unit correcting an estimated flow rate, estimated by the flow rate sensor, based on the pressure insensitive calibration value and a measured value of the pressure sensor
Data Source
AI summary
A flow rate control system including a flow rate controller controlling a flow rate of a fluid supplied to a controlled object to keep a desired flow rate set value is provided, and includes a flow rate sensor, a pressure sensor measuring a pressure of a primary side of the flow rate controller, a PI calibration value determination unit determining a PI calibration value based on at least a physical property coefficient according to a physical property value of the fluid, a correction unit correcting an estimated flow rate, based on the PI calibration value and a measured value, and a drive control circuit adjusting an opening of a valve supplying the fluid to the controlled object based on the estimated value and controlling the flow rate of the fluid. A flow rate is accurately calculated regardless of types of a fluid in the pressure insensitive type flow rate controller.