Streambed Thermal Property Instrument

James Alwel Dayie, Utah State University

This work made publicly available electronically on May 27, 2012.


The purpose of this research, the Streambed thermal Property Instrument (SPI) is to determine the applicability of this instrument for in situ thermal (conductivity and diffusivity) and porous flow (magnitude and direction) measurements. Currently, no such thermal instrument exists for such in situ measurements and the reason for developing this unique instrument, the SPI to fill the technology gap in sediment thermal property measurement devices. Prior to testing the instrument under controlled laboratory conditions to determine its functionality through a series of static and flow tests, the instrument was designed and built. A lab-sized version of an actual river called a flow cell with a gravity-driven flow was also built, making it possible for testing the SPI under controlled lab conditions .The instrument was tested in the flow case by fixing the instrument in two orientations in the saturated porous media (glass particles). Results from the static tests indicated that these bulk thermal measurements (diffusivity and conductivity) can be off the expected value by as much as 15% while the porous flow measurements (magnitude and direction) displayed more variability in results for the two orientations of the probe for the flow rate range considered. This variability in flow measurements has been partly attributed to the movement of the offset probes during insertion and rotation and the large size of the center probe of the SPI. The findings from this research has made it possible for more advanced research in this field by using computer simulations to make possible, accurate porous flow measurements using a large scale thermal probe such as the SPI.