Differential Scanning Calorimeter Temperature Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Thermo-analytical instruments using the classic heat flux principle face issues with sample temperature deviation from the set program temperature, non-linear temperature changes, and sensitivity to inaccuracies in thermal properties, leading to erroneous measurement results, especially for small-scale instruments like chip-type calorimeters.
Innovation Solution
An enhanced heat flux mode is implemented in a thermo-analytical instrument, where the heating power is controlled to actively follow the measured sample temperature, reducing temperature deviations and improving the accuracy of heat flow measurements by directly controlling the sample temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the classic heat flux principle is used with a common heater and reference position control, then the instrument structure is simple and easy to manufacture, but the sample temperature deviates substantially from the set program temperature and shows non-linear behavior during thermal events
Solution Approach 1:
The patent divides the heating system into separate heaters for the sample position and reference position, rather than using a single common heater. This segmentation allows independent control of each position's temperature, enabling the sample temperature to follow the programmed temperature profile accurately while the reference position can be controlled separately for heat flow measurement.
Solution Approach 2:
Instead of controlling the reference position temperature as in classic heat flux instruments, the patent inverts the control approach by actively controlling the sample position temperature to follow the programmed profile. The reference position becomes the measurement position where heat flow is determined, reversing the traditional roles.
2Device complexity
If the heating power is controlled by reference position temperature in heat flux mode, then the control system is simple, but the sample temperature can be essentially non-linear with respect to time during thermal events
Solution Approach 1:
The patent implements a feedback control system where the actual sample temperature is continuously measured and used to adjust the heating power to the sample position. This feedback loop ensures that the sample temperature follows the programmed temperature profile linearly, even during thermal events, by compensating for heat flow changes in real-time.
Solution Approach 2:
The control system transitions from a static reference-based control to a dynamic sample-based control. The heating power is continuously adjusted based on the actual sample temperature and the desired temperature profile, allowing the system to adapt to changing thermal conditions during measurements.
3Measurement precision
If the net sample heat flow is determined from temperature signals with high accuracy requirements, then measurement sensitivity is high, but inaccuracies in thermal properties lead to erroneous measurement results
Solution Approach 1:
The patent introduces the temperature difference between sample and reference positions as an intermediary measurement parameter. Instead of directly measuring heat flow with high sensitivity to thermal property inaccuracies, the system measures the temperature difference which is then used to calculate heat flow through well-defined thermal conductivity paths, reducing sensitivity to property uncertainties.
Solution Approach 2:
The patent changes the measurement parameter from direct heat flow measurement to temperature difference measurement. By measuring temperature difference and using the known thermal conductivity of the support structure, the system calculates heat flow in a way that is less sensitive to inaccuracies in sample thermal properties.
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 thermal lag, enhances the steepness of the phase transition peak, and results in faster relaxation and more accurate heat flow measurements, improving the reproducibility and accuracy of results.
Implementation Method 1
a first sensor for measuring a sample temperature at the sample position
Implementation Method 2
a second sensor for measuring a reference temperature at the reference position
Implementation Method 3
heating means associated with the sample position and the reference position
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
Thermo-analytical instrument, in particular a differential scanning calorimeter, and a method for controlling the thermo-analytical instrument. Said thermo-analytical instrument comprising a sample position (201, 401) for receiving a sample (206), a reference position (202, 402), heating means associated with the sample position (201, 401) and the reference position (202, 402), means for setting a predetermined temperature program of nominal values of temperature versus time, a first sensor (407) for measuring a sample temperature (TS) at the sample position (201, 401), and further comprising a controller, which controls the heating power of said heating means, characterized in that the heating power of said heating means (203, 403, 204, 404) is controlled so as to cause said measured sample temperature (TS) to essentially follow said predetermined temperature program.