In-Situ Thermometer Calibration via Phase Transformation
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Solution Overview
Problem
Current thermometer calibration methods require removal from the measuring point, leading to disadvantages such as reduced dynamic range and potential damage from escaping fixed point substances, and reference elements are prone to aging and sensor drift.
Innovation Solution
A device with a temperature sensor and a reference element composed of materials experiencing phase transformations at specific temperatures, utilizing dynamic excitation signals to detect phase transformations without releasing latent heat, allowing for in-situ calibration and validation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a miniaturized fixed point cell is provided in a thermometer for in-situ calibration, then calibration can be performed in the installed state, but the dynamic range of the sensor is lessened and response time to temperature change is deteriorated
Solution Approach 1:
The invention extracts the calibration function from a separate fixed point cell and integrates it into the temperature sensor itself. The temperature sensor is designed to detect the phase transformation temperature of the substance directly at the measuring point, eliminating the need for a separate calibration cell that would restrict dynamic range and slow response time.
Solution Approach 2:
The invention merges the temperature sensing function and the calibration reference function into a single integrated device. The temperature sensor both measures the process temperature and detects the phase transformation temperature of the calibration substance, combining two functions that were previously separate into one compact unit.
2Ease of operation
If a fixed point cell is provided in a thermometer for in-situ calibration, then calibration can be performed in the installed state, but the fixed point substance could escape from the cell leading to damage or destruction of the thermometer
Solution Approach 1:
The invention extracts the calibration substance from an enclosed cell structure and places it directly in contact with the temperature sensor at the measuring point. This eliminates the cell containment structure that could fail and release the fixed point substance, while still allowing the sensor to detect the phase transformation temperature.
Solution Approach 2:
The temperature sensor performs self-calibration by detecting the phase transformation temperature of a substance that is present at the measuring point. The sensor uses its own detection capability to identify the calibration temperature without requiring external calibration equipment or enclosed calibration cells.
3Ease of operation
If reference elements are used for in-situ calibration based on characteristic lines or curves, then calibration can be performed in the installed state, but the characteristic lines or curves are subject to aging effects and sensor drift
Solution Approach 1:
The invention uses the phase transformation temperature of a substance as the calibration reference. Phase transformation temperatures are fundamental physical properties that remain constant over time and are not subject to aging or drift like electronic reference elements. The temperature sensor detects this invariant temperature point to perform calibration.
Solution Approach 2:
The invention replaces expensive, drift-prone electronic reference elements with a simple, stable physical reference based on phase transformation. This physical reference does not degrade over time like electronic components, providing long-term stability without requiring replacement or recalibration of the reference element itself.
4Measurement precision
If calibration is performed in calibration baths or ovens, then accurate calibration can be achieved, but the thermometer must be deinstalled from the measuring point
Solution Approach 1:
The invention extracts the calibration reference (phase transformation temperature) from external calibration equipment and brings it to the measuring point. This allows the temperature sensor to be calibrated in-situ by detecting the phase transformation temperature of a substance present at the measurement location, eliminating the need to remove the sensor from the process.
Solution Approach 2:
The invention uses a phase transformation substance as an intermediary to transfer the calibration reference temperature to the temperature sensor at the measuring point. This intermediary enables accurate calibration without requiring direct contact with external calibration equipment or removal of the sensor from the process environment.
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, drift-free calibration and validation of temperature sensors by utilizing phase transformations in solid-phase materials, ensuring measurement integrity and stability.
Implementation Method 1
the reference element is composed at least partially of a material, in the case of which at least one phase transformation occurs at at least a first predetermined phase transformation temperature
Data Source
AI summary
The present disclosure relates to a device for determining and/or monitoring temperature of a liquid, comprising a temperature sensor, a reference element for in-situ calibration and/or validation of a temperature sensor and an electronics unit, wherein the reference element is composed at least partially of a material, in the case of which at least one phase transformation occurs at at least a first predetermined phase transformation temperature in a temperature range relevant for calibrating the temperature sensor, in which phase transformation the material remains in the solid phase. According to the present disclosure, the electronics unit is embodied to supply the reference element with a dynamic excitation signal. Furthermore, the present disclosure relates to a method for calibration and/or validation of a temperature sensor based on a device of the invention.