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US 6,431,747 B1Granted
Heat flux differential scanning calorimeter sensor
AssigneeTA Instruments, Inc.
InventorRobert L. Danley
Life of this patent
Estimating the term…
Abstract
A sensor for a heat flux differential scanning calorimeter in which one absolute temperature measurement and two differential temperature measurements are used. The sensor is calibrated and used based on a four-term model heat flow equation. The calibration is carried out in two experiments which are used to calculate the sensor thermal resistance for the sample and reference positions, respectively, and the sensor heat capacity for the sample and reference positions, respectively. Differential scanning calorimeters using this sensor exhibit improved resolution, improved baseline performance and improved dynamic response.
Claims83
A sensor in an oven of a heat flux differential scanning calorimeter comprising:
- (a) an absolute temperature detector which measures one of a base temperature, a sample temperature and a reference temperature as an absolute temperature;
- (b) a first differential temperature detector which measures one of the difference between the sample temperature and the base temperature, the difference between the reference temperature and the base temperature and the difference between the sample temperature and the reference temperature as a first differential temperature;
- (c) a second differential temperature detector which measures another one of the difference between the sample temperature and the reference temperature, the difference between the sample temperature and the base temperature and the difference between the reference temperature and the base temperature as a second differential temperature;
- wherein the base temperature is measured directly or is determined from at least one of the absolute temperature, the first differential temperature and the second differential temperature;
- wherein the base temperature is used to control the power to the oven;
- and
- wherein the sensor is calibrated by running a first experiment with a first calibration set, said first calibration set comprising a first sample calibration sample on a sample position of the differential scanning calorimeter and a first reference calibration sample on a reference position of the differential scanning calorimeter, and then running a second experiment with a second calibration set comprising a second sample calibration sample on the sample position of the differential scanning calorimeter and a second reference calibration sample on the reference position of the differential scanning calorimeter.
4 more elements
A sensor for an oven of a heat flux differential scanning calorimeter comprising:
- (a) an absolute temperature detector measuring a base temperature at a base of the sensor;
- (b) a first differential temperature detector measuring the difference between a sample temperature at a sample position and the base temperature;
- (c) a second differential temperature detector measuring the difference between the sample temperature and a reference temperature at a reference position;
- wherein the sensor is calibrated by running a first experiment with an empty differential scanning calorimeter cell and a second experiment with a sample calibration sample in the sample position and a reference calibration sample in the reference position.
1 more element
A method for calibrating a sensor for a heat flux differential scanning calorimeter having an absolute temperature measurement detector, a first differential temperature measurement detector and a second differential temperature measurement detector comprising:
- (a) placing a first sample calibration sample on a sample position of the differential scanning calorimeter and a first reference calibration sample on a reference position of the differential scanning calorimeter;
- (b) running a first experiment comprising a first isothermal segment, a second constant heating rate segment and a third isothermal segment, and measuring an absolute temperature with the absolute temperature detector, a first differential temperature using the first differential temperature measurement detector and a second differential temperature using the second differential temperature measurement detector;
- (c) placing a second sample calibration sample on a sample position of the differential scanning calorimeter and a second reference calibration sample on a reference position of the differential scanning calorimeter;
- (d) running a second experiment comprising the first isothermal segment, the second constant heating rate segment and the third isothermal segment, and measuring the absolute temperature with the absolute temperature detector, the first differential temperature using the first differential temperature measurement detector and the second differential temperature using the second differential temperature measurement detector;
- and
- (e) calculating the sensor sample thermal resistance, the sensor reference thermal resistance, the sensor sample thermal capacitance and the sensor reference thermal capacitance,
- wherein the sensor is calibrated by calculating the sensor sample thermal resistance, the sensor reference thermal resistance, the sensor sample thermal capacitance and the sensor reference thermal capacitance.
4 more elements
A method for operating a heat flux differential scanning calorimeter having a sensor 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 the sample position, comprising:
- (a) the step of calibrating the sensor;
- and
- (b) operating the differential scanning calorimeter.
A method for calibrating a sensor for a heat flux differential scanning calorimeter having an absolute temperature measurement detector, a first differential temperature measurement detector and a second differential temperature measurement detector comprising:
- (a) running a first experiment comprising a first isothermal segment, a second constant heating rate segment and a third isothermal segment with an empty differential scanning calorimeter cell, and measuring a first differential temperature using the first differential temperature measurement detector and a second differential temperature using the second differential temperature measurement detector;
- (b) placing a sample calibration sample on a sample position of the differential scanning calorimeter and a reference calibration sample on a reference position of the differential scanning calorimeter;
- (c) running a second experiment comprising a fourth isothermal segment, a fifth constant heating rate segment and a sixth isothermal segment, and simultaneously measuring the first differential temperature using the first differential temperature measurement detector and the second differential temperature using the second differential temperature measurement detector;
- and
- (d) calculating a sensor sample thermal resistance, a sensor reference thermal resistance, a sensor sample thermal capacitance and a sensor reference thermal capacitance.
2 more elements
A sensor for a heat flux differential scanning calorimeter comprising:
- (a) a sample platform mounted on the top of a sample cylindrical tube, said tube having a cylindrical wall thickness;
- (b) a reference platform mounted on the top of a reference cylindrical tube, said tube having a cylindrical wall thickness;
- (c) a base attached to the bottom of the sample cylindrical tube and the bottom of the reference cylindrical tube;
- and
- (d) a base thermocouple for measuring an absolute temperature at a base position on the base, a first differential thermocouple configuration for measuring a sample/base differential temperature at the sample platform with respect to the base, and a second differential thermocouple configuration for measuring a sample/reference differential temperature at the sample platform with respect to the reference platform.
2 more elements
A method for calibrating a heat flux differential scanning calorimeter having a base temperature detector measuring the temperature at a base position, a first differential temperature detector measuring the temperature difference between a sample position and the base position, and a second differential temperature detector measuring the temperature difference between the sample position and reference position comprising:
- (a) running a first experiment comprising a first isothermal segment, a second constant heating rate segment and a third isothermal segment with an empty differential scanning calorimeter cell, and measuring a first differential temperature using the first differential temperature measurement detector and a second differential temperature using the second differential temperature measurement detector;
- (b) placing a sample calibration sample on a sample position of the differential scanning calorimeter and a reference calibration sample on a reference position of the differential scanning calorimeter;
- (c) running a second experiment comprising a fourth isothermal segment, a fifth constant heating rate segment and a sixth isothermal segment, and simultaneously measuring the first differential temperature using the first differential temperature measurement detector and the second differential temperature using the second differential temperature measurement detector;
- and
- (d) calculating a sensor sample thermal resistance, a sensor reference thermal resistance, a sensor sample thermal capacitance and a sensor reference thermal capacitance, wherein the differential scanning calorimeter is calibrated by calculating the sensor sample thermal resistance, the sensor reference thermal resistance, the sensor sample thermal capacitance and the sensor reference thermal capacitance.
2 more elements
A calorimeter having an oven, a sample position and a reference position comprising:
- (a) an absolute temperature detector which measures one of a base temperature, a sample temperature and a reference temperature as an absolute temperature;
- (b) a first differential temperature detector which measures one of the difference between the sample temperature and the base temperature, the difference between the reference temperature and the base temperature and the difference between the sample temperature and the reference temperature as a first differential temperature;
- and
- (c) a second differential temperature detector which measures another one of the difference between the sample temperature and the reference temperature, the difference between the sample temperature and the base temperature and the difference between the reference temperature and the base temperature as a second differential temperature;
- wherein the base temperature is measured directly or is determined from at least one of the absolute temperature, the first differential temperature and the second differential temperature,
- wherein the base temperature is used to control power to the oven, and wherein the sample position is effectively independent from the reference position.
3 more elements
A method of calibrating a calorimeter having a reference position and a sample position for a predetermined operating temperature range comprising the steps of:
- (a) running a first experiment with nothing on the sample position or on the reference position, said first experiment comprising the steps of:
- (i) sensing at least one absolute temperature and two differential temperatures;
- (ii) maintaining a steady temperature below the operating temperature range;
- (iii) heating the calorimeter at a first constant heating rate to a temperature above the predetermined operating range;
- (iv) determining at least one time constant;
- (b) running a second experiment with a calibration sample on at least one of the sample position and the reference position comprising the steps of:
- (i) sensing at least one absolute temperature and two differential temperatures;
- (ii) maintaining a steady temperature below the operating temperature range;
- (iii) heating the calorimeter at a second constant heating rate to a temperature above the predetermined operating range;
- and
- (iv) determining at least one capacitance and at least one resistance, wherein the calorimeter is calibrated by determining the at least one time constant, the at least one capacitance and the at least one resistance.
8 more elements
A method of calibrating a calorimeter having an oven, a reference position and a sample position for a predetermined operating temperature range comprising the steps of:
- (a) running a first experiment with a sample calibration sample on the sample position and a reference calibration sample on the reference position, said first experiment comprising the steps of:
- (i) sensing an absolute temperature and two differential temperatures;
- (ii) maintaining a steady temperature below the predetermined operating temperature range;
- (iii) heating the calorimeter at a first constant heating rate to a temperature above the predetermined operating range;
- (iv) determining at least one time constant of the reference and sample time constants;
- (b) running a second experiment with the sample calibration sample on the sample position and the reference calibration sample on the reference position comprising the steps of:
- (i) sensing an absolute temperature and two differential temperatures;
- (ii) maintaining a steady temperature below the predetermined operating temperature range;
- (iii) heating the calorimeter at a second constant heating rate to a temperature above the predetermined operating range;
- and
- (iv) determining at least one sensor capacitance and at least one sensor resistance,
- wherein the first constant heating rate differs substantially from the second constant heating rates and wherein the calorimeter is calibrated by determining the at least one time constant, the at least one sensor capacitance and the at least one sensor resistance.
9 more elements
A method for reducing relative errors in absolute temperature measurements due to differences in temperature sensors used in a heat flux differential scanning calorimeter containing a sample position, a reference position, and a base, the method comprising the steps of:
- (a) measuring a temperature of the base;
- (b) measuring a differential temperature between the sample position and the base;
- (c) measuring a differential temperature between the sample position and the reference position;
- (d) determining at least one time constant, at least one thermal resistance and at least one thermal capacitance based upon a four-term heat flow equation, and
- (e) using the at least one time constant, at least one thermal resistance and at least one thermal capacitance to reduce the relative errors in absolute temperature measurements.
2 more elements
A heat flux differential scanning calorimeter comprising:
- (a) a base having a base top side and a base underside;
- (b) a sample cylindrical tube attached to the base top side;
- (c) a reference cylindrical tube attached to the base top side;
- (d) a sample platform mounted on top of the sample cylindrical tube, the sample platform having a sample platform top side and a sample platform underside;
- (e) a reference platform mounted on top of the reference cylindrical tube, the reference platform having a reference platform top side and a reference platform underside;
- (f) a sample area temperature detector attached to the sample platform underside, wherein the sample area temperature detector is thermoelectrically positive;
- (g) a reference area temperature detector attached to the reference platform underside, wherein the reference area temperature detector is thermoelectrically positive;
- and
- (h) a thermocouple attached to the base, wherein the thermocouple has a positive element and a negative element,
- wherein the differential scanning calorimeter measures a ΔT voltage between the sample area temperature detector and the reference area temperature detector,
- wherein the differential scanning calorimeter measures a ΔTo voltage between the sample area temperature detector and the positive element of the thermocouple, and
- wherein the differential scanning calorimeter measures a To voltage between the positive element and the negative element.
9 more elements
A calorimeter having a sample position and a reference position comprising:
- (a) an absolute temperature detector which obtains an absolute temperature measurement by measuring one of a base temperature, a sample temperature and a reference temperature;
- (b) a first differential temperature detector which obtains a first differential temperature measurement by measuring one of the difference between the sample temperature and the base temperature, the difference between the reference temperature and the base temperature and the difference between the sample temperature and the reference temperature;
- and
- (c) a second differential temperature detector which obtains a second differential temperature measurement by measuring another one of the difference between the sample temperature and the reference temperature, the difference between the sample temperature and the base temperature and the difference between the reference temperature and the base temperature,
- wherein the calorimeter determines the heat flow to the sample from the absolute temperature detector measurement, the first differential temperature detector measurement and the second differential temperature detector measurement,
- and wherein the sample position is effectively independent from the reference position.
3 more elements
Dependencies are inferred from the claim text.