Loading patent…
AssigneeAgence Nationale de Valorisation de la Recherche (ANVAR)
InventorLeon Ter-Minassian
Estimating the term…
A calorimeter includes an adiabatic enclosure surrounding a tube for supporting a sample. In the enclosure is a control chamber in thermal contact with the sample-carrier tube and containing a substantially perfect gas. The temperature of the sample is kept constant during a change of state by varying the pressure of this gas. A differential gas thermometer provides an indication of the difference between the temperature of the sample and that of a thermally insulated reference body which is initially at the same temperature as the sample. An automatic control system varies the pressure of the gas in the control chamber in the sense which tends to cancel any temperature variations detected by the differential gas thermometer. The gas pressure is varied by means of a vertical passage which has its upper end connected to the control chamber and its lower end connected to receive hydraulic liquid from a volumetric pump actuated by the control system. The cross-section of the vertical passage decreases towards the top in such a way that the level of the liquid in the passage is in substantially linear relationship to the pressure of the gas. The quantity of thermal energy given out or taken up by the sample during the change of state is determined by measuring the variation in the pressure of the gas in the control chamber. The reference body is located coaxially around the sample-carrier tube and is coaxially surrounded by a cylindrical baffle at a thermostatically controlled temperature. The adiabatic enclosure is evacuated, and has reflective inside walls.
A calorimetry process for determining the quantity of thermal energy given out or taken up by a sample during an isothermal change of state between two physico-chemical states, wherein said sample is maintained at a constant temperature during said change of state by varying the pressure of a gas contained in a control chamber which is in thermal contact with said sample, the quantity of thermal energy given out or taken up being determined by measuring the variation of the pressure of said gas.
A calorimeter, comprising an adiabatic enclosure for receiving a sample, temperature sensing means in said enclosure responsive to the temperature of said sample, a control chamber in said enclosure, in thermal contact with said sample and containing a gas, means external to said enclosure for varying the pressure of said gas, means external to said enclosure for sensing the pressure of said gas, and a control system adapted to actuate said pressure varying means in response to temperature variations detected by said temperature sensing means, to vary the pressure of said gas in the sense required to reduce said temperature variations to zero, the quantity of thermal energy given out or taken up by said sample during an isothermal change between two physico-chemical states being determined by measuring the variation of the pressure of said gas.
Dependencies are inferred from the claim text.