Dielectric spectroscopic sensing of fine liquid droplets in an airstream

Authors

  • Safal Kshetri Agricultural and Biosystems Engineering, Iowa State University, Ames, IA, USA
  • Brian L. Steward Agricultural and Biosystems Engineering, Iowa State University, Ames, IA, USA http://orcid.org/0000-0002-3842-9908
  • Stuart J Birrell Agricultural and Biosystems Engineering, Iowa State University, Ames, IA, USA

DOI:

https://doi.org/10.1080/14399776.2017.1376999

Keywords:

Dielectric sensor, dielectric constant, dielectric spectroscopy, pneumatics, principal component analysis, linear discriminant analysis

Abstract

Contamination of compressed air can reduce its utility and lead to costly failure of pneumatic components. Monitoring contaminants in the compressed air could help take preventive measures to maintain usefulness of the pneumatic systems. Dielectric spectroscopy has good potential as a viable commercial sensor technology for pneumatic systems as it can differentiate dielectric properties of the air with and without contaminants. It could also be used to detect the presence of oil mist, required for lubricating pneumatic components. Two tests were performed using a sensor capable of measuring the dielectric spectrum of the fluid mixture. The objective was to investigate the efficacy of dielectric spectroscopy in detecting the presence of deionised water and light lubricant oil in an airstream. These liquids were atomised using industrial spray nozzles, then entrained in an airstream and passed through the sensor. Spectroscopic measurements were acquired and multivariate classifiers were developed using principal component analysis and linear discriminant analysis to investigate the sensor’s performance in differentiating the presence and absence of liquid droplets in the airstream. The classifier was able to separate the two cases suggesting dielectric spectroscopy could be used to detect these two liquids in an airstream.

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Author Biographies

Safal Kshetri, Agricultural and Biosystems Engineering, Iowa State University, Ames, IA, USA

Safal Kshetri is a PhD student in Agricultural and Biosystems Engineering at Iowa State University. He received his BS in Biological and Agricultural Engineering from the University of Idaho and his MS in Agricultural and Biosystems Engineering from Iowa State University. His research interests include mechatronics, automation and computational intelligence.

Brian L. Steward, Agricultural and Biosystems Engineering, Iowa State University, Ames, IA, USA

Brian L. Steward is a professor of Agricultural and Biosystems Engineering at Iowa State University. He received his BS and MS in Electrical Engineering from South Dakota State University, and his PhD in Agricultural Engineering from the University of Illinois at Urbana-Champaign. His research and teaching areas include
dynamic systems modelling and simulation, fluid power engineering and technology, computational intelligence and sustainable engineering.

Stuart J Birrell, Agricultural and Biosystems Engineering, Iowa State University, Ames, IA, USA

Stuart J Birrell is a Kinze Manufacturing professor of Agricultural and Biosystems Engineering at Iowa State University. His degrees, all in Agricultural Engineering, include BS from the University of Natal (1984), MS (1987) and PhD (1995) from the University of Illinois. His research focuses on harvest technologies, biomass harvesting
and logistics and sensor development for advanced machinery control and in precision agriculture.

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Published

2018-03-01

Issue

Section

Original Article