Hybrid Thermal Pressure Sensor Flow Rate Calibration
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Solution Overview
Problem
Thermal mass flow sensors are slow to respond to changes in fluid flow rate due to their inherent time constant, leading to inaccurate mass flow rate calculations during fluctuations, and existing devices rely solely on thermal measurements without combining thermal and pressure-based measurements.
Innovation Solution
A system and method that combines thermal and pressure sensor signals to determine fluid flow rate, using thermal sensors to generate a thermal sensor-based mass flow rate and pressure sensors to generate a pressure sensor-based mass flow rate, with calibration factors adjusting the pressure sensor-based rate to improve accuracy during stable and fluctuating conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If thermal mass flow sensors are used to measure fluid flow rate, then measurement accuracy is maintained during stable conditions, but response time is slow (2-4 seconds time constant) causing inaccurate measurements during flow fluctuations
Solution Approach 1:
The patent combines a thermal mass flow sensor with a pressure sensor to create a hybrid measurement system. The thermal sensor provides accurate measurements during stable conditions, while the pressure sensor provides rapid response during flow fluctuations. The electronics process both signals together to generate a corrected mass flow rate that maintains accuracy across all operating conditions.
Solution Approach 2:
The pressure sensor acts as an intermediary that detects flow changes rapidly and provides signal information that complements the thermal sensor's accurate but slow measurements. The electronics use the pressure sensor signal to correct and accelerate the thermal sensor's response, effectively using the pressure sensor as a mediator to bridge the response time gap.
2Speed
If mathematical acceleration techniques are applied to thermal mass flow sensor signals, then response time is reduced, but noise in the thermal sensor signal increases
Solution Approach 1:
The pressure sensor serves as an intermediary that provides clean, noise-free signal information about flow changes. Instead of applying noisy mathematical acceleration to the thermal sensor signal, the system uses the pressure sensor's rapid response as a clean reference to correct the thermal sensor output, avoiding the introduction of additional noise.
Solution Approach 2:
The electronics process the pressure sensor signal and use it to generate a correction signal that is fed back to adjust the thermal sensor's mass flow rate output. This feedback mechanism allows the system to respond quickly to flow changes while maintaining signal quality, as the correction is based on the clean pressure sensor measurements rather than noisy mathematical operations.
3Device complexity
If only thermal based flow measurement is used, then device complexity is low, but measurement accuracy deteriorates during fluctuating flow conditions
Solution Approach 1:
The patent merges a thermal mass flow sensor with a pressure sensor into a single integrated measurement system. The electronics combine signals from both sensors to produce a corrected mass flow rate that maintains accuracy during both stable and fluctuating conditions. This combination resolves the limitation of thermal-only systems while adding only moderate 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
The combined approach provides accurate mass flow rate measurements during both stable and fluctuating conditions, enhancing the responsiveness and accuracy of fluid flow rate determination compared to relying solely on thermal sensors.
Implementation Method 1
thermal mass flow sensors determine mass flow via a measurement of heat transfer or energy consumption during a transfer of heat
Implementation Method 2
one particular type of thermal mass flow sensor determines flow rate by heating or cooling a fluid as it flows through a conduit and measuring a temperature change in the fluid
Implementation Method 3
The at least one pressure sensor generates a pressure sensor signal, which indicates the pressure of the fluid
Data Source
AI summary
The present invention relates to a system, method, and computer program product for determining the flow rate of a fluid. The system, method, and computer program product generate a thermal sensor based mass flow rate for the fluid, where the thermal sensor based mass flow rate is determined at least in part from the thermal sensor signal (36). The system, method, and computer program product generate a pressure sensor based mass flow rate for the fluid, wherein the pressure sensor based mass flow rate is determined at least in part from the pressure sensor signal (51a). The system, method, and computer program product generate at least one calibration factor (ψ) using the thermal sensor based mass flow rate and the pressure sensor based mass flow rate. The system, method, and computer program product may generate a calibrated pressure sensor based mass flow rate by using the at least one calibration factor (ψ) to modify the pressure sensor based mass flow rate. The system, method, and computer program product may generate a calibrated thermal sensor based mass flow rate by using the at least one calibration factor (ψ) to modify the thermal sensor based mass flow rate.