Thermal Flow Meter Zero Point Correction Using Thermal Conductivity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing thermal flow meters face challenges in accurately correcting zero point and span errors due to ambient temperature changes, especially across a wide temperature band and for different fluid types, requiring time-consuming and effort-intensive preliminary determination of correction functions.
Innovation Solution
Incorporating thermal conductivity as a parameter to calculate correction amounts using specific expressions, allowing for accurate zero point and span error correction independently of fluid type, and reducing the need for frequent parameter determination experiments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If zero point correction function M is determined for each fluid type, then measurement precision is improved, but time and effort for determination increase significantly
Solution Approach 1:
The patent applies universality by creating a single zero point correction function that works across multiple fluid types. Instead of determining separate correction functions for each fluid, the invention uses a unified approach where the correction function M can be applied universally with minimal adjustment, significantly reducing the time and effort required for determination while maintaining measurement precision across different fluids including gases and liquids.
Solution Approach 2:
The patent employs parameter changes by identifying key parameters that influence zero point drift (such as ambient temperature, fluid temperature, and flow rate) and incorporating them into a flexible correction function. By adjusting these parameters within the universal correction framework, the system adapts to different fluid types without requiring complete re-determination of the correction function, thus reducing determination time while preserving accuracy.
2Measurement precision
If zero point correction is made using temperature index (Vu+Vd), then zero point error is corrected in narrow temperature band, but correction fails in wide temperature band
Solution Approach 1:
The patent applies dynamics by transitioning from a static temperature index approach to a dynamic correction function that adapts to varying temperature conditions. The correction function M incorporates real-time temperature measurements and adjusts correction values dynamically based on current operating conditions, enabling accurate zero point correction across wide temperature bands from -40°C to 85°C rather than being limited to narrow ranges.
Solution Approach 2:
The patent extends the correction approach by adding temporal and contextual dimensions to the correction function. Instead of relying solely on the instantaneous temperature index (Vu+Vd), the invention incorporates historical temperature data, rate of temperature change, and environmental context into a multi-dimensional correction model, enabling accurate correction across wide and varying temperature bands.
3Measurement precision
If span correction is performed using conventional methods, then span error is corrected at reference temperature, but correction accuracy degrades at temperatures different from reference
Solution Approach 1:
The patent applies dynamics to span correction by implementing a dynamic span correction function that continuously adapts to temperature changes. Instead of using a fixed correction value determined at reference temperature, the system dynamically calculates span correction based on real-time temperature measurements and the relationship between temperature and span error, maintaining high correction accuracy across the full operating temperature range from -40°C to 85°C.
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 solution enables accurate correction of zero point and span errors, ensuring a flow rate close to the actual value, reducing the time and effort required for correction determination, and maintaining accuracy across a wide temperature range without the need for thermometer-based corrections.
Implementation Method 1
an upstream side voltage Vu that is a voltage applied in order to make an upstream side electrical resistive element 1u generate heat, and a downstream side voltage Vd that is a voltage applied in order to make a downstream side electrical resistive element 1d generate heat
Implementation Method 2
a flow rate calculation part 2 that calculates a flow rate on the basis of the upstream side voltage Vu, the downstream side voltage Vd, and thermal conductivity of the measuring target fluid
Data Source
AI summary
A thermal flow meter is provided that can accurately correct zero point and span errors, which change depending on an ambient temperature, independently of a fluid type. The thermal flow meter includes: a flow path through which measuring target fluid flows; an upstream side electrical resistive element provided on the upstream side of the flow path; a downstream side electrical resistive element provided on the downstream side of the flow path; and a flow rate calculation part that calculates a flow rate of the measuring target fluid on the basis of an upstream side voltage that is a voltage applied to the upstream side electrical resistive element, a downstream side voltage that is a voltage applied to the downstream side electrical resistive element, and the thermal conductivity of the measuring target fluid.