Dew point measurement using dual quartz crystal resonator sensor

In order to solve the problem that the quartz crystal resonator (QCR) dew point sensor in the measurement process cannot effectively eliminate the effect of temperature on the frequency, a new sensor based on the dual quartz crystal resonator (D-QCR) has been developed. The sensor combined Peltier module with two QCRs and the two QCRs were cooled by the same Peltier. One of these two QCRs only provides a reference frequency without gas contact and the other QCR is used for measuring dew point with gas contact. The frequency difference was calculated between the frequency difference of two QCRs at the initial state and the frequency difference of two QCR when condensation occurs. The observed value was used as the calibration value of dew point recognition. The calibration experiment proved that the 159 Hz can be used as the calibration value for the dew point identification. The nine groups of dew point environments in the range of −3.7 °C to 17 °C DP were selected to be measured. During the experiments, the maximum measurement error was less than 0.47 °C DP when compared with the MICHELL S4000 dew point meter. The results show that this method can effectively eliminate the measurement error caused by temperature. It proved that the sensor is high accurate and has a good and long-term stability.