초록 ▼

A new adiabatic scanning calorimeter allows the thermal mass of a high-pressure reaction vessel to be dynamically compensated during a test. This allows the effective Φ factor for the experiment to be reduced to 1.0 without the use of complex pressure balancing equipment. Endothermic events can

A new adiabatic scanning calorimeter allows the thermal mass of a high-pressure reaction vessel to be dynamically compensated during a test. This allows the effective Φ factor for the experiment to be reduced to 1.0 without the use of complex pressure balancing equipment. Endothermic events can be quantified and sample specific heats can be measured. The time required for test completion is much shorter than for conventional adiabatic calorimeters, thus considerably improving apparatus productivity. The sensitivity to exotherm detection is at least as good as existing adiabatic calorimeters employing the Heat-Wait-Search strategy, but does depend on the temperature-scanning rate. In addition, the heat of reaction is obtained without reference to the heat capacity of the sample, pressure is measured continuously, reactants may be injected into the test vessel and the sample can be mixed during the test.

대표청구항 ▼

The invention claimed is: 1. A method, for use in an adiabatic scanning calorimeter, for removing the influence of the mass of a bomb from the measurement of the thermal properties of a sample undergoing an exothermic or endothermic reaction, comprising the steps of: a) placing a sample in a bomb;

The invention claimed is: 1. A method, for use in an adiabatic scanning calorimeter, for removing the influence of the mass of a bomb from the measurement of the thermal properties of a sample undergoing an exothermic or endothermic reaction, comprising the steps of: a) placing a sample in a bomb; b) initially heating the sample at a predetermined rate of temperature increase, by adjusting the power output of a sample heater; c) calculating the rate of heat loss to the bomb from the sample; d) adjusting the sample heater power output to equal the heat loss rate to the sample bomb; e) adjusting the power input to one or more guard heaters to prevent the loss of heat from the exterior surface of the bomb; and f) calculating the amount of heat absorbed or evolved from the sample to change the sample temperature by a defined amount, by subtracting the heat supplied by the sample heater from the change in the sensible heat of the sample and the sample bomb. 2. The use of the method of claim 1 to calculate the heat capacity of a sample, in a temperature range in which there are no sample exotherms or endotherms, comprising the additional steps of (g) establishing the heat capacity of said bomb (h) calculating the amount of energy used by the sample heater to raise the temperature of the bomb; (i) subtracting the energy used to heat the bomb from the total energy supplied to find the heat energy absorbed by the sample, and (j) dividing the heat absorbed by the sample by the sample mass to obtain the heat capacity of a sample. 3. The use of the method of claim 1 for determining the amount of energy absorbed by a sample during an endotherm, the method comprising the additional steps of: (g) selecting a predetermined rate of temperature rise that is sufficiently slow to maintain essentially isothermal conditions within the bomb; (h) increasing power to the sample heater as required to maintain the predetermined rate of temperature rise; and (i) calculating the amount of energy absorbed by a sample during the endotherm as the integral of the increase in the sample heater power output above the power applied by the sample heater prior to the start of the endotherm. 4. The use of the method of claim 1 to determine the sample energy release rate or absorption rate by subtracting the sample heater power output from the sum of the rates of change of the sensible energies of the sample and the sample bomb, by the use of the equation description="In-line Formulae" end="lead" dW/dt=(MsCs+MbC b)(dTw/dt)-Pdescription="In-line Formulae" end="tail" or an equation functionally equivalent thereto, where (dW/dt) is the sample energy release rate, P is the sample heater power and (M sCs+MbCb)(dTw/dt) is the rate of change of the sensible energy of the sample and the sample bomb, wherein the rate of change of the sensible energy of the sample and the sample bomb are obtained from the method of claim 1 together with the measured rate of temperature rise of the sample and the sample bomb. 5. The use of the method of claim 4 to calculate the total energy released or absorbed by the sample during an exotherm or endotherm, the method comprising the additional step of integrating the equation in method 17 between the temperature limits at the beginning of the reaction and the end of the reaction. 6. A method, for use in an adiabatic scanning calorimeter, for determining the heat capacity of a sample at a temperature in a certain range, the range characterized in the absence of exotherms and endotherms, the method comprising the steps of: a) establishing the heat capacity of a bomb b) placing the sample in the bomb; c) heating the sample at a constant rate using a sample heater; d) preventing heat loss from the bomb using one or more guard heaters; e) calculating the amount of energy used by the sample heater to raise the temperature of the bomb; f) subtracting the energy used to heat the bomb from the total energy supplied to find the heat energy absorbed by the sample, and g) dividing the heat absorbed by the sample by the sample mass to obtain the heat capacity. 7. A method, for use in an adiabatic scanning calorimeter, for determining the amount of energy absorbed by a sample during an endotherm, the method comprising the steps of: a) placing a sample in a sample bomb, the sample bomb having a known mass and heat capacity; b) heating the sample using a sample heater at a constant rate of applied power, the rate being selected to be sufficiently slow to maintain essentially isothermal conditions within the bomb; c) preventing heat loss from the external surface of the bomb using one or more guard heaters; d) calculating the amount of energy absorbed by the sample during the endotherm from the measured change in the rate of temperature decrease of the sample and bomb and the known heat capacity and mass of the sample bomb and the known power applied to the sample by the sample heater. 8. A method, for use in an adiabatic scanning calorimeter, for determining the amount of energy released or absorbed by a sample during an exothermic or endothermic reaction, the method comprising the steps of: a) placing a sample in a sample bomb; b) heating the sample using a sample heater at a constant rate of temperature increase, the rate being selected to be sufficiently slow to maintain essentially isothermal conditions within the bomb; c) preventing heat loss from the external surface of the bomb using one or more guard heaters; d) decreasing or increasing the power to the sample heater as required to maintain the pre-selected rate of temperature rise; and e) calculating the amount of energy released or absorbed by the sample during the reaction from the difference between the power required to maintain the selected rate of temperature rise, and the power that would have been required to maintain said rate of temperature rise of the sample and the sample bomb if no reaction had occurred in the sample. 9. A method, for use in an adiabatic scanning calorimeter having two or more sample bombs, for determining the amount of energy released or absorbed by multiple samples during a chemical or physical change, the method comprising the steps of: a) placing the samples in the sample bombs; b) heating the samples using sample heaters at a constant rate of temperature increase, the rate being pre-selected to be sufficiently slow to maintain essentially isothermal conditions within the bombs; c) preventing heat loss from the external surfaces of the bombs using one or more guard heaters; d) decreasing or increasing the power to the sample heaters as required to maintain the pre-selected rate of temperature rise within the samples; and e) calculating the amount of energy released or absorbed by the samples during the reactions from the difference between the power required to maintain the selected rate of temperature rise, and the power that would have been required to maintain said rate of temperature rise of the samples and the sample bombs if no reaction had occurred in the samples. 10. A method, for use in an adiabatic calorimeter, for determining the energy release or absorption rate of a sample, the method comprising the steps of a) placing a sample in a bomb; b) heating the sample and the bomb at a constant power input using a sample heater; c) preventing heat loss from the bomb and sample using one or more guard heaters; d) calculating the sample energy release or absorption rate from the measurement of the rate of temperature change of the system and the constant power output from the heater by the use of the equation description="In-line Formulae" end="lead" dW/dt=P0[{(dTw/dt)/(dT 0/dt)}-1]description="In-line Formulae" end="tail" or an equation functionally equivalent thereto, where (dW/dt) is the sample energy release (or absorption) rate; (dT0/dt) is the initial rate of temperature rise of the system due to the constant power input, P0, and (dTw/dt) is the rate of temperature rise of the sample and the sample bomb. 11. The use of the method of claim 10 to calculate the total energy released or absorbed by the sample during an exothermic or endothermic reaction, the method comprising the additional step of integrating the equation in method 19 between the temperature limits at the beginning of the reaction and the end of the reaction.