Instrumentation for surface geothermal data acquisition aiming at sustainable heat exchangers

This work discusses the development of a standard multisensor arrangement on a five-meter long rod to be vertically buried underground, using digital temperature sensors. With this purpose, it was assembled a dedicated data acquisition board to allow continuous measurements of the vertical temperatures underground profile of the soil in Santa Maria-RS from Sep 2013 to Jul 2014. It was observed that the soil temperature decreases as the depth increases. In addition, the temperature of the soil tends to become constant with an increasing depth, converging to the average value of the temperature for the location in analysis. The results show that the soil temperature at the depth of five meters, measured in the experimental campus CEESP, varies between 19 °C and 22 °C. During this period, extremes of the ambient temperatures were below 0 °C and above 40 °C and them presented phase delays along the year.