Category: Transient Plane Source
Author(s): Bjorn Palm, Cke Melinder, JosC) AcuC1a, Monika Ignatowicz
Keywords: Borehole heat exchanger, Denaturing agents, Ethanol, Ground source heat pump, Pressure drop, Secondary fluid, Thermal Conductivity, Thermophysical properties, Transient Plane Source, Transient plane source (TPS) method
Abstract: Borehole heat exchangers are used in conjunction with ground source heat pumps in Nordic countries. Aqueous ethanol solutions are commonly used with other secondary fluids such as water in borehole heat exchangers to decrease the freezing point of the liquid. However, ethanol based mediums contain denaturing agents that can affect the thermal properties of the secondary fluids. In this study, a Thermal Constants Analyzer used the Transient Plane Source method to measure the thermal conductivity of a secondary fluid field sample, pure ethanol 20wt-%, and ethanol 20wt-% including denaturing additives. According to the results, the thermal conductivity increased as the temperature of each sample heightened, but the sample of ethanol 20wt-% with additives had the highest thermal conductivity other than the original field sample and distilled water.
Reference: Proceedings World Geothermal Congress (2015) 1-10