| 摘要 |
<p>The intensity of a ray passed through the mixture is measured at ambient temperature to calculate the value of a property which varies as a function of temperature and of gas concentration. The value of this property at a reference temperature other than ambient is determined using the temperature function, and the gas concentration value is determined using the gas concentration function The function varying with concentration is determined during a preliminary calibration stage during which a number of values of the property are found for different gas concentrations at the reference temperature. The property is the transmission coefficient T(N,t) of the gaseous mixture defined as T(N,t) = U(N,t)/U(0,t), where T(N,t) is the transmission coefficient at temperature t with a concentration N of the gas, and U(N,t) and U(0,t) represent the intensity of an electrical signal from detectors (16, 18) at temperature t when the mixture contains a concentration N and a zero concentration of the gas respectively. U(0,t) is found during the calibration stage. The transmission coefficient at the reference temperature is determined using T(N,tref) = T(N,ta) (LnT(N0,tref)/LnT(N0,ta) or T(N,tref) = 1-(1- T(N,ta))(1-T(N0,tref)/(1-T(N0,ta)), where T(N,tref) and T(N,ta) represent the transmission coefficient for a concentration M of gas at reference and ambient temperatures, and T(N0,tref) and T(N0,ta) represent the transmission coefficient for a zero concentration of gas at reference and ambient temperatures. During calibration, the electrical signal for concentration N0 at different temperatures is measured, including at reference and ambient temperatures. The transmission coefficient for each measurement is calculated. Device to carry out the above process with an optical analysis cell (12) containing means (14) of emitting the ray across the cell and means (16, 18) of detecting the ray, connected to means (34) of calculating the gas concentration at various temperatures.</p> |
