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A Double Transducer for High Precision Ultrasonic Time-Domain Reflectometry Measurements.

Stade S, Hakkarainen T, Kallioinen M, Mänttäri M, Tuuva T - Sensors (Basel) (2015)

Bottom Line: A double transducer described in this study eliminates the need for a separate reference transducer because in the double transducer the reference measurement is included in the design of the transducer holder.Two sensors in the same holder require less space.Other advantage is that the double transducer can be placed near the measurement target and hence the local sonic velocity can be determined.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Separation Technology, School of Engineering Science, Lappeenranta University of Technology, P.O. Box 20, Lappeenranta FI-53851, Finland. stade@lut.fi.

ABSTRACT
Membrane fouling, where unwanted particles accumulate on the membrane surface and reduce its permeability, causes problems in membrane filtration processes. With ultrasonic time-domain reflectometry (UTDR) it is possible to measure the extent of membrane fouling and hence take actions to minimize it. However, the usability of UTDR is very limited to constant filtration conditions if the sonic velocity, which has a great impact on UTDR measurement accuracy, is unknown. With a reference transducer the actual sonic velocity can be measured. This requires another transducer to be installed in the module, where there may be only limited space or the module dimensions may not be suitable for the reference transducer. A double transducer described in this study eliminates the need for a separate reference transducer because in the double transducer the reference measurement is included in the design of the transducer holder. Two sensors in the same holder require less space. Other advantage is that the double transducer can be placed near the measurement target and hence the local sonic velocity can be determined.

No MeSH data available.


Maximum measurement errors caused by changes in the sonic velocity due to temperature changes. Calculated from an empirical model made by Belogol’skii et al. [16] Temperature = 25 °C.
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sensors-15-15090-f001: Maximum measurement errors caused by changes in the sonic velocity due to temperature changes. Calculated from an empirical model made by Belogol’skii et al. [16] Temperature = 25 °C.

Mentions: The measurement setup may greatly affect the measurement accuracy in practice [15]. The module has to be robust so that pressure or temperature changes does not affect its dimensions. High precision UTDR measurements with a reference transducer favor short distances where the ultrasonic path of the distance measurement is as representative as possible with the path of the reference transducer measurement. Even small differences in sonic velocities in those paths may cause an error when the operation conditions vary. For example a 1 °C temperature change for 25 °C water, when the measurement distance is 17.8 mm, leads to a 32 μm error. If the measurement distance were to be as short as 5 mm the error would be ~9 μm. The same error is valid for UTDR measurements where the sonic velocity is assumed to be constant. Figure 1 shows how the measurement distance and temperature change of water affect the measurement error.


A Double Transducer for High Precision Ultrasonic Time-Domain Reflectometry Measurements.

Stade S, Hakkarainen T, Kallioinen M, Mänttäri M, Tuuva T - Sensors (Basel) (2015)

Maximum measurement errors caused by changes in the sonic velocity due to temperature changes. Calculated from an empirical model made by Belogol’skii et al. [16] Temperature = 25 °C.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4541822&req=5

sensors-15-15090-f001: Maximum measurement errors caused by changes in the sonic velocity due to temperature changes. Calculated from an empirical model made by Belogol’skii et al. [16] Temperature = 25 °C.
Mentions: The measurement setup may greatly affect the measurement accuracy in practice [15]. The module has to be robust so that pressure or temperature changes does not affect its dimensions. High precision UTDR measurements with a reference transducer favor short distances where the ultrasonic path of the distance measurement is as representative as possible with the path of the reference transducer measurement. Even small differences in sonic velocities in those paths may cause an error when the operation conditions vary. For example a 1 °C temperature change for 25 °C water, when the measurement distance is 17.8 mm, leads to a 32 μm error. If the measurement distance were to be as short as 5 mm the error would be ~9 μm. The same error is valid for UTDR measurements where the sonic velocity is assumed to be constant. Figure 1 shows how the measurement distance and temperature change of water affect the measurement error.

Bottom Line: A double transducer described in this study eliminates the need for a separate reference transducer because in the double transducer the reference measurement is included in the design of the transducer holder.Two sensors in the same holder require less space.Other advantage is that the double transducer can be placed near the measurement target and hence the local sonic velocity can be determined.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Separation Technology, School of Engineering Science, Lappeenranta University of Technology, P.O. Box 20, Lappeenranta FI-53851, Finland. stade@lut.fi.

ABSTRACT
Membrane fouling, where unwanted particles accumulate on the membrane surface and reduce its permeability, causes problems in membrane filtration processes. With ultrasonic time-domain reflectometry (UTDR) it is possible to measure the extent of membrane fouling and hence take actions to minimize it. However, the usability of UTDR is very limited to constant filtration conditions if the sonic velocity, which has a great impact on UTDR measurement accuracy, is unknown. With a reference transducer the actual sonic velocity can be measured. This requires another transducer to be installed in the module, where there may be only limited space or the module dimensions may not be suitable for the reference transducer. A double transducer described in this study eliminates the need for a separate reference transducer because in the double transducer the reference measurement is included in the design of the transducer holder. Two sensors in the same holder require less space. Other advantage is that the double transducer can be placed near the measurement target and hence the local sonic velocity can be determined.

No MeSH data available.