Thermal Flowmeter Circumferential Detection Segmentation
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Solution Overview
Problem
Thermal flowmeters face challenges in measuring flow rates with high precision when the velocity distribution of liquids is nonuniform, particularly due to flexible flow passage tubes that can bend, leading to variations in measured flow rates based on the bonding position of detection substrates.
Innovation Solution
A thermal flowmeter with multiple detection sections, each equipped with a heating resistor and temperature detecting resistor, are placed at predetermined intervals around the circumference of the measurement tube, allowing the control section to calculate flow rates from signals in multiple directions, thereby averaging or weighting these signals to cancel out velocity distribution nonuniformities and improve measurement precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single detection section is used to simplify the device structure, then the device complexity is reduced, but the measurement precision deteriorates when velocity distribution is nonuniform
Solution Approach 1:
The detection function is segmented into multiple detection sections (first, second, third, and fourth detection sections) positioned at different circumferential locations around the measurement tube. Each detection section independently measures flow rate based on local velocity, and the control section combines these measurements to calculate the overall flow rate, thereby achieving accurate measurement under nonuniform velocity distribution conditions.
2Measurement precision
If multiple detection sections are added to improve measurement precision under nonuniform flow, then the measurement precision is improved, but the device complexity increases
Solution Approach 1:
Multiple detection sections are merged into a single integrated measurement system where the control section performs unified calculation processing. The control section combines signals from all detection sections using a calculation formula to determine the overall flow rate, effectively merging the functions of multiple sensors into a coordinated measurement system that achieves high precision without proportionally increasing system complexity.
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 approach enables precise measurement of flow rates even with nonuniform velocity distributions, reduces variations in flow rate calculations, and allows for detection of abnormal installation states, enhancing overall measurement accuracy and reliability.
Implementation Method 1
a heating resistor and a temperature detecting resistor bonded to a measurement tube along a flowing direction of a liquid, and measures a flow rate of the liquid flowing in the measurement tube from a timing of heating the liquid by the heating resistor
Implementation Method 2
a heating resistor and a temperature detecting resistor bonded to a measurement tube along a flowing direction of a liquid
Data Source
AI summary
A thermal flowmeter including a measurement tube that has an inflow port into which a liquid flows and an outflow port that allows the liquid which flows in from the inflow port to flow out, and has an internal flow passage where the liquid flows formed to extend along an axis, and a plurality of detection sections each of which has a heating resistor and a temperature detecting resistor along the axis and is provided at the measurement tube, and a control section that calculates a flow rate of the liquid flowing through the internal flow passage based on signals from the plurality of detection sections, wherein the plurality of detection sections are respectively provided with predetermined intervals left in a circumferential direction with the axis as a center.