Thermal Mass Flow Meter Temperature Pressure Correction
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Solution Overview
Problem
Conventional mass flow meters face challenges in accurately measuring mass flow rates of fluids with varying thermal physical properties due to temperature and pressure changes, as they often rely on reference signals and correction coefficients that do not account for fluid-specific changes in these conditions.
Innovation Solution
A capillary heating type thermal mass flow meter equipped with temperature and pressure sensors, which calculates a corrected mass flow rate using temperature and pressure coefficients stored in a data storage device, applying the formula Fc=Fm(1+α×ΔT+β×ΔP) to account for deviations from calibration conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional mass flow meters use reference signals and correction coefficients for temperature and pressure compensation, then measurement accuracy is improved, but device complexity and data storage requirements increase
Solution Approach 1:
The patent changes the parameters stored in memory from extensive correction coefficient tables to simple temperature and pressure coefficients (α and β). The correction formula Fc=Fm(1+α×ΔT+β×ΔP) uses these two parameters to compensate for temperature and pressure variations, significantly reducing data storage requirements while maintaining measurement accuracy across different operating conditions.
Solution Approach 2:
The patent extracts only the essential temperature and pressure coefficients from the complex correction system, separating them from the full correction coefficient tables. This extraction allows the system to maintain accuracy by accounting for the most significant environmental variations while eliminating the need to store and process extensive correction data for all possible conditions.
2Measurement precision
If mass flow meters store extensive correction data for different temperatures and pressures, then measurement accuracy across varying conditions is improved, but data storage capacity and calculation load increase
Solution Approach 1:
The patent reduces the quantity of stored data by changing from storing extensive correction coefficient tables to storing only two parameters: temperature coefficient (α) and pressure coefficient (β). This parameter reduction maintains the ability to correct measurements under varying conditions while dramatically decreasing the data storage capacity required in the flow meter's memory.
3Device complexity
If conventional systems use fixed correction coefficients, then device simplicity is maintained, but measurement accuracy deteriorates when fluid thermal physical properties change with temperature and pressure
Solution Approach 1:
The patent introduces dynamic correction by using temperature and pressure coefficients that allow the correction factor to vary with operating conditions. The formula Fc=Fm(1+α×ΔT+β×ΔP) dynamically adjusts the mass flow rate based on actual temperature and pressure deviations from calibration conditions, enabling accurate measurement of fluids whose thermal properties change with temperature and pressure while maintaining relative system simplicity.
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 method allows for accurate and simple measurement of mass flow rates across different temperatures and pressures, reducing measurement errors and eliminating the need for extensive data storage and calculation loads, while maintaining high accuracy even for fluids with non-constant temperature and pressure coefficients.
Implementation Method 1
when the pair of sensor wires is made to generate heat by applying a predetermined electric voltage (or a predetermined electric current)
Implementation Method 2
heat generated from the sensor wires is removed (drawn) by a fluid which flows through the sensor tube
Implementation Method 3
electrical resistance value of the sensor wire on the upstream side becomes lower than an electrical resistance value of the sensor wire on the downstream side
Data Source
AI summary
In a capillary heating type thermal type mass flow meter comprising a sensor configured to detect temperature and pressure of a fluid and a correction means configured to correct a mass flow rate based on said temperature and said pressure, change rates of the mass flow rate of the fluid with respect to temperature and pressure have been previously acquired, and the mass flow rate is corrected based on said temperature and said pressure as well as these change rates. Thereby, the mass flow rate can be measured accurately and simply even when the temperature and/or pressure of the fluid, whose mass flow rate is to be measured, change.