Microwave Flow-Rate Measurement Using Microstrip Heating
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Solution Overview
Problem
Existing flow-rate measuring methods using thermal markers have limited sensitivity and accuracy due to the wide heat distribution from external heaters, resulting in a restricted measurable flow-rate range of 10 ml/min or lower, with a limited difference between the upper and lower limits.
Innovation Solution
A flow-rate measuring method employing a microwave heating unit to generate a thermal marker within the fluid, using a microstrip or coaxial transmission line to intensively heat the fluid from outside the tube, allowing for a larger temperature difference and a clearly distinguishable thermal marker, which can be detected over a greater distance, thereby increasing the measurable flow-rate range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an external heater is used to heat the fluid from outside the tube, then the fluid can be heated without direct contact, but the heat transmission causes a wide heated region and reduces measurement precision
Solution Approach 1:
The patent replaces the conventional external heater (thermal conduction system) with a laser beam (optical system) to heat the fluid. The laser beam directly irradiates the fluid through the tube wall, substituting thermal conduction through the tube wall with optical energy absorption by the fluid, thereby achieving localized heating without the wide heat distribution caused by external heaters
Solution Approach 2:
The patent applies local quality by concentrating the heating action to a specific microscopic region of the fluid through laser beam irradiation. The laser beam creates a localized thermal marker with a narrow width corresponding to the beam diameter, rather than heating a wide region, thus improving the precision of flow-rate measurement by maintaining a sharp thermal gradient
2Measurement precision
If a laser beam is used to directly heat the fluid, then the thermal marker is localized and measurement accuracy is improved, but the low-output lasers available limit the measurable flow-rate range to 10 ml/min or lower
Solution Approach 1:
The patent changes the key parameter of laser output power by selecting a laser beam with higher output power than conventional low-output lasers. This parameter change enables the thermal marker to produce sufficient temperature change even in fluids flowing at higher rates (up to 100 ml/min), thereby expanding the measurable flow-rate range while maintaining the localization benefits of laser heating
Solution Approach 2:
The patent employs periodic (pulsed) laser irradiation to generate the thermal marker. By using pulsed action rather than continuous heating, the system can create sharp thermal markers that are detectable even when the fluid is flowing at higher rates, effectively expanding the measurable flow-rate range while maintaining measurement precision
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 method achieves a wider measurable flow-rate range, up to 100 ml/min, with enhanced usability by localizing the heating and minimizing heat absorption at the external surface, allowing for more accurate flow-rate measurements.
Implementation Method 1
the heating unit heats the fluid by a microwave heating technique, and microwaves are applied to the fluid by using a transmission line
Implementation Method 2
a heating unit that heats the fluid flowing through the tube from the outside thereof so as to generate a heated portion
Implementation Method 3
the thermal-marker detecting unit uses, for example, a laser beam as detection light for detecting a change in the absorbance of light of a specific wavelength in the fluid
Data Source
AI summary
A measurable flow-rate range is increased to enhance usability. A flow-rate measuring method for measuring the flow rate of a fluid inside a tube is provided. This method uses a thermal-marker generator that heats the fluid flowing through the tube from the outside thereof to generate a thermal marker in the fluid inside the tube and a thermal-marker detector disposed downstream of the thermal-marker generator and configured to detect the thermal marker in the fluid inside the tube generated by the thermal-marker generator, so as to measure the flow rate on the basis of the distance between the thermal-marker generator and the thermal-marker detector, a time period between a point at which the thermal marker in the fluid inside the tube is generated by the thermal-marker generator and a point at which the thermal marker is detected by the thermal-marker detector, and the cross-sectional area of the tube. In this method, the thermal-marker generator heats the fluid by a microwave heating technique, and microwaves are applied to the fluid by using a microstrip line.