Vibronic Mass Flow Transducer Temperature Gradient Compensation
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Solution Overview
Problem
Vibronic measuring systems face significant measurement errors, particularly in fluids with low specific heat capacity and rapidly changing temperatures, leading to inaccuracies in mass flow rate measurements, especially at low Reynolds numbers and mass flow rates below 1 kg/h.
Innovation Solution
The system employs a transducer device with two temperature sensors positioned at different points along the tube to account for temperature gradients, generating mass flow measurement values that are independent of temperature differences, ensuring accuracy across varying conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single temperature sensor is used in the transducer device, then the device complexity is reduced, but measurement precision deteriorates due to inability to account for temperature gradients along the tube
Solution Approach 1:
The temperature sensing function is segmented into multiple independent sensors positioned at different locations along the tube. Specifically, a first temperature sensor is positioned at a first location and a second temperature sensor is positioned at a second location, allowing each sensor to independently measure temperature at its specific position. This segmentation enables the system to detect temperature gradients along the tube, which is critical for accurate mass flow rate measurement in fluids with low specific heat capacity.
2Measurement precision
If temperature compensation is not implemented, then the device complexity is reduced, but measurement precision deteriorates under rapidly changing temperature conditions
Solution Approach 1:
The system implements feedback-based temperature compensation by continuously monitoring temperature at multiple locations using the temperature sensors and using this information to correct mass flow rate measurements. The measured temperature values from the first and second temperature sensors are fed back into the measurement system to compensate for temperature-induced errors, ensuring accurate mass flow rate determination even under rapidly changing temperature conditions.
3Adaptability or versatility
If the tube is exposed to rapidly changing temperatures, then the adaptability of the measuring system is improved, but measurement precision deteriorates due to temperature gradients affecting the measurement
Solution Approach 1:
The system applies local quality by positioning temperature sensors at specific locations along the tube where temperature gradients are most significant. The first temperature sensor is positioned at a first location and the second temperature sensor is positioned at a second location, allowing each sensor to locally measure temperature conditions at its specific position. This localized temperature measurement approach enables the system to adapt to rapidly changing temperature conditions while maintaining measurement precision through location-specific temperature 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
This approach reduces measurement errors to less than 0.05% and 1 kg/h, maintaining high accuracy even under challenging conditions such as low specific heat capacity fluids and rapidly changing temperatures.
Implementation Method 1
a first temperature sensor which is thermally conductively coupled to the wall of the first tube and which is positioned less far from the first end of the first tube than from the second end of said first tube and which is provided to sense a first measuring point temperature
Implementation Method 2
a second temperature sensor which is thermally conductively coupled to the wall of the first tube and which is positioned less far from the second end of the first tube than from the first end of said first tube and which is provided to sense a second measuring point temperature
Implementation Method 3
the first tube which comprises a lumen surrounded by a wall and which extends from an inlet-side first end to an outlet-side second end and which is provided to be flowed through by at least a partial volume of the fluid from the inlet-side first end toward the outlet-side second end and in the process is caused to vibrate
Implementation Method 4
a first vibration sensor for sensing mechanical vibrations of the first tube, which sensor is positioned less far from the first end of the first tube than from the second end of said first tube and which sensor is provided to sense vibration movements of the first tube at an inlet-side first vibration measuring point formed by means of said vibration sensor and to generate a first vibration signal representing said vibration movements
Data Source
AI summary
A measuring system includes a measuring and operation electronic unit (ME) and a transducer device electrically coupled thereto. The transducer device (MW) has at least one tube, through which fluid flows during operation and which is caused to vibrate meanwhile, a vibration exciter, two vibration sensors for generating vibration signals, and two temperature sensors for generating temperature measurement signals (θ1, θ2). The temperature sensors are coupled to a wall of the tube in a thermally conductive manner. The ME is designed to feed electrical power into the at least one vibration exciter to cause mechanical vibrations of the tube by an electrical excitation signal. The ME generates a mass flow sequence representing the instantaneous mass flow rate (m) of the fluid, so that, at least for a reference mass flow rate, the mass flow measurement values are independent of the temperature difference.