Thermal Gas Property Sensor for Differential Pressure Compensation
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Solution Overview
Problem
Calorimetric-type thermal flow sensors face limitations in measuring differential pressure due to sensitivity to varying gas properties, particularly when gas composition changes uncontrollably, requiring compensation for accurate measurements.
Innovation Solution
A thermal gas property sensor system that generates a reference overpressure in a cavity connected to a flow channel, using flow-sensitive elements and a processing unit to determine gas flow parameters, allowing for compensation of differential pressure measurements based on physical properties and ambient conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If thermal flow sensors are used to measure differential pressure, then pressure measurement capability is provided, but sensitivity to varying gas properties causes measurement inaccuracy when gas composition changes
Solution Approach 1:
The patent employs feedback by measuring the actual gas flow through the channel using flow-sensitive elements, then using this measurement to compensate for the differential pressure reading. The system continuously monitors gas flow parameters and adjusts the pressure measurement accordingly, creating a closed-loop system that maintains accuracy despite gas composition changes.
Solution Approach 2:
The invention changes the measurement parameters by not only measuring pressure difference but also measuring gas flow rate, temperature, and other gas properties. By measuring multiple parameters simultaneously and using them together in compensation calculations, the system transforms a single-parameter measurement into a multi-parameter measurement system that can account for gas composition variations.
2Measurement precision
If thermal sensing elements are used to detect gas flow, then gas flow parameter measurement is enabled, but temperature gradients induced by flow cause sensitivity to ambient temperature variations
Solution Approach 1:
Temperature is measured as one of the parameters by the sensing elements, and this temperature measurement is fed back into the compensation algorithm. The system uses the measured temperature to correct the gas flow and pressure readings, eliminating the error introduced by ambient temperature variations.
Solution Approach 2:
The thermal sensing elements serve multiple functions: they detect gas flow through temperature gradients, measure ambient temperature, and provide data for compensating both pressure and flow measurements. This multi-functional approach allows a single sensing element to address multiple sources of measurement error.
3Adaptability or versatility
If gas correction factors are introduced for different gases, then operation at different gases becomes possible, but uncontrollable gas composition variations during operation cannot be compensated
Solution Approach 1:
Instead of relying on pre-programmed correction factors for known gases, the system continuously measures actual gas flow parameters and uses this real-time feedback to compensate measurements. This approach adapts to any gas composition automatically, whether known or unknown, by measuring the actual behavior of the gas rather than assuming it matches a predetermined profile.
Solution Approach 2:
The measurement system serves itself by using its own measurements of gas flow, temperature, and other parameters to compensate for gas composition variations. The system does not require external information about gas identity or pre-configured correction factors; it autonomously adapts to the actual gas conditions through self-measurement and self-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 measurement of gas properties and compensated differential pressure, reducing the adverse effects of varying gas compositions and ambient conditions on sensor responses.
Implementation Method 1
A reference overpressure of a gas is generated and/or may be determined in a cavity pneumatically connected to the thermal flow sensor with a flow channel
Implementation Method 2
thermal sensing elements can be located in micro channels formed in a semiconductor die or sensor package. The thermal sensors can be sensitive to gas flow in the channels due to temperature gradients in the sensing area induced by flow of the gas
Data Source
Figure 1
Figure 2A~2C
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AI summary
The present disclosure provides thermal gas property sensors and compensated differential pressure sensors, as well as methods for measuring a physical property of a gas and methods for compensating differential pressure sensors. A reference overpressure of a gas is generated in a cavity. Based on the flow of the gas from the cavity through a channel, properties of the gas are identified.