Differential scanning calorimeter accounting for heat leakage
AssigneeWaters Investments Limited
InventorRobert Danley
Life of this patent
Estimating the term…
Abstract
A method and system for calculating a heat flow to a sample in a differential scanning calorimeter (DSC). The DSC has a sensor within an enclosure comprising an absolute temperature measurement detector for measuring the temperature of a base position on the sensor, a first differential temperature detector for measuring the temperature difference between a sample position and the base position, and a second differential temperature detector for measuring the temperature difference between a reference position and a sample position. Thermal resistances and heat capacities of the DSC are calibrated. The DSC is operated, and the heat flow to the sample is calculated using a method that accounts for the leakage heat flows.
Claims16
1-57. (canceled)
A differential scanning calorimeter (DSC) system comprising:
- a sensor within an enclosure comprising:
- an absolute temperature measurement detector for measuring temperature of a base position on the sensor,
- a first differential temperature detector for measuring a temperature difference between a sample position and the base position, and
- a second differential temperature detector for measuring a temperature difference between a reference position and a sample position,
- means for calibrating the DSC to account for heat leakages between the sample and reference and the enclosure, wherein calibration is performed when the DSC is empty and a first leakage resistance Rlc is added in parallel to a measuring thermal resistance of a sample Rs and a second leakage resistance Rlc is added in parallel to a measuring thermal resistance of a reference Rr, thereby decreasing an effectiv resistance of the measuring thermal resistance;
- operating the DSC;
- and
- means for calculating the heat flow to the sample in accordance with the calibration of the DSC.
A differential scanning calorimeter having a sensor within an enclosure comprising an absolute temperature measurement detector for measuring a temperature of a base position on the sensor, a first differential temperature detector for measuring a temperature difference between a sample position and the base position, and a second differential temperature detector for measuring a temperature difference between a reference position and a sample position, further comprising:
- means for calibrating the DSC by accounting for heat leakage between the sample and reference and the enclosure, wherein calibration is performed with first and second calibration samples without pans placed on respective sample and reference sides of the DSC, and a leakage thermal resistance Rlr between the first calibration sample and an enclosure is added in parallel to a measuring thermal resistance of the sample calorimeter, and a leakage thermal resistance Rls between the second calibration sample and an enclosure is added in parallel to a measuring thermal resistance of the reference calorimeter;
- and
- means for calculating the heat flow to the sample in accordance with the calibration of the DSC.
A method for determining thermal properties of a sample using a differential scanning calorimeter (DSC) comprising a sensor having a base position, a sample position and a reference position, comprising the steps of:
- placing the sample on the sample position;
- measuring a sample heat flow qs , measuring a reference heat flow qs , measuring a thermal resistance between a sample pan and a sensor Rps , measuring a thermal resistance between a reference pan and the sensor Rpr, measuring a thermal resistance for heat leakage for the sample pan Rls , measuring a thermal resistance for heat leakage for the reference pan Rlr;
- and
- calculating the heat flow to the sample according to:
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- and its mathematical equivalents;
- wherein ΔT0 is the temperature difference between the sample position and the base position;
- ΔT is the temperature difference between the sample position and the reference position;
- and
- dTps/dt and dTpr/dt are the derivatives with respect to time of the temperature of the sample position and the temperature of the reference position, respectively.
Dependencies are inferred from the claim text.