High Precision UTDR Measurements by Sonic Velocity Compensation with Reference Transducer

Sensors

Sam Stade¹  Mari Kallioinen¹  Mika Mänttäri¹ 

[1] Laboratory of Separation Technology, LUT Chemtech, Lappeenranta University of Technology, P.O. Box 20, Lappeenranta FI-53851, Finland; E-Mails:

关键词: ultrasonic time-domain reflectometry;    time-of-flight measurement;    reference transducer;    environmental compensation;    flat-sheet membrane module;   

DOI  :  10.3390/s140711682

来源: mdpi

【 摘 要 】

An ultrasonic sensor design with sonic velocity compensation is developed to improve the accuracy of distance measurement in membrane modules. High accuracy real-time distance measurements are needed in membrane fouling and compaction studies. The benefits of the sonic velocity compensation with a reference transducer are compared to the sonic velocity calculated with the measured temperature and pressure using the model by Belogol'skii, Sekoyan et al. In the experiments the temperature was changed from 25 to 60 °C at pressures of 0.1, 0.3 and 0.5 MPa. The set measurement distance was 17.8 mm. Distance measurements with sonic velocity compensation were over ten times more accurate than the ones calculated based on the model. Using the reference transducer measured sonic velocity, the standard deviations for the distance measurements varied from 0.6 to 2.0 μm, while using the calculated sonic velocity the standard deviations were 21–39 μm. In industrial liquors, not only the temperature and the pressure, which were studied in this paper, but also the properties of the filtered solution, such as solute concentration, density, viscosity, etc., may vary greatly, leading to inaccuracy in the use of the Belogol'skii, Sekoyan et al. model. Therefore, calibration of the sonic velocity with reference transducers is needed for accurate distance measurements.

【 授权许可】

CC BY   
© 2014 by the authors; licensee MDPI, Basel, Switzerland.