Thermal Flow Sensor Condensation Detection
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Solution Overview
Problem
Thermal flow measuring devices face errors in measuring gas flow due to aggregate state changes such as condensation or desublimation, which alter heat transfer and result in inaccurate flow measurements, limiting accurate measurement of non-dry gas flows.
Innovation Solution
A method to recognize and monitor aggregate state changes by determining phase boundary lines using temperature, chemical composition, and pressure data, analyzing disturbances in temperature difference and heating power signals to differentiate between mass flow and state changes, employing signal processing techniques to detect and correct measurement signal disturbances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If thermal flow measurement is used for gas flow measurement, then flow measurement capability is provided, but measurement accuracy deteriorates due to aggregate state changes such as condensation or desublimation
Solution Approach 1:
The patent converts the harmful effect of aggregate state changes into a useful measurement signal. By detecting temperature differences and heating power variations caused by condensation or desublimation, the system identifies these state changes and compensates for their impact on flow measurement accuracy, transforming a previously harmful interference into a detectable and correctable phenomenon
Solution Approach 2:
The system continuously monitors temperature differences between sensors and heating power requirements, using this feedback to detect aggregate state changes in real-time. This feedback mechanism allows the system to identify when condensation or desublimation occurs and adjust measurements accordingly, maintaining accuracy despite changing aggregate states
2Reliability
If conventional thermal flow measuring devices are used, then simple flow measurement is achieved, but measurement reliability deteriorates in the presence of condensation or desublimation
Solution Approach 1:
The patent transforms the harmful alteration of heat transfer during aggregate state changes into a beneficial diagnostic signal. By monitoring how heat transfer patterns change during condensation or desublimation, the system detects these events and compensates for their impact, converting a reliability-threatening factor into a useful detection mechanism
Solution Approach 2:
The system introduces temperature difference measurements and heating power monitoring as intermediary parameters that mediate between the aggregate state changes and the final flow measurement. These intermediaries provide early warning signals of state changes before they significantly corrupt the flow measurement, allowing for timely compensation
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
Enables accurate monitoring and correction of aggregate state changes, ensuring precise flow measurement even in the presence of condensation or desublimation, effectively addressing the limitations of conventional thermal flow measuring devices.
Implementation Method 1
The cooling rate caused thereby is a measure for the flow velocity
Implementation Method 2
heat is transported away from the heated temperature sensor by the flowing medium
Implementation Method 3
the temperature sensor itself is a resistance element, e.g. an RTD (Resistance Temperature Device) sensor, which is heated by conversion of electrical power
Implementation Method 4
The dependence of the heat transfer coefficient on the mass flow of the medium through the measuring tube, or through the pipeline, is utilized in thermal, flow measuring devices for determining the mass flow
Data Source
AI summary
A method for determining and/or monitoring aggregate state changes on a thermal, flow measuring device of at least a first part of a measured medium, wherein, as a result of the temperature of the medium being measured, as a result means of the chemical composition of the medium being measured and as a result of the partial pressure of the at least first part of the medium being measured and/or as a result of the total pressure of the medium being measured, at least one phase boundary line of the at least first part of the medium being measured is ascertained. At least a first measurement signal is provided from a temperature difference between a first temperature sensor and a second temperature sensor of the thermal, flow measuring device and/or from a heating power supplied the medium being measured, wherein, in the case of a state of the at least first part of the medium being measured in the region of the phase boundary line of the first part of the medium being measured, disturbances of predetermined type in the measurement signal are detected as aggregate state changes on the thermal flow device of the at least first part of the medium being measured.