Laboratory Experimental Investigation of Heat Transport in 1 Fractured Media

9 Low enthalpy geothermal energy is a renewable resource that is still underexploited nowadays, in 10 relation to its potential for development in the society worldwide. Most of its applicabilities have 11 already been investigated, such as: heating and cooling of private and public buildings, roads defrost, 12 cooling of industrial processes, food drying systems, desalination. 13 One of the major limitations related to the choice of installing low enthalpy geothermal power plants 14 regards the initial investment costs. 15 In order to increase the optimal efficiency of installations which use groundwater as geothermal 16 resource, flow and heat transport dynamics in aquifers need to be well characterized. Especially in 17 fractured rock aquifers these processes represent critical elements that are not well known. Therefore 18 there is a tendency to oversize geothermal plants. 19 In literature there are very few studies on heat transport especially in fractured media. 20 This study is aimed to deepen the understanding of this topic through heat transport experiments in 21 fractured network and their interpretation. 22 The heat transfer tests have been carried out on the experimental apparatus previously employed to 23 perform flow and tracer transport experiments, which has been modified in order to analyze heat 24 transport dynamics in a network of fractures. In order to model the obtained thermal breakthrough 25 curves, the Explicit Network Model (ENM) has been used, which is based on an adaptation of a 26 Tang’s solution for the transport of the solutes in a semi-infinite single fracture embedded in a porous 27 matrix. 28 Parameter estimation, time moment analysis, tailing character and other dimensionless parameters 29 have permitted to better understand the dynamics of heat transport and the efficiency of heat exchange 30 Nonlin. Processes Geophys. Discuss., doi:10.5194/npg-2016-54, 2016 Manuscript under review for journal Nonlin. Processes Geophys. Published: 10 October 2016 c © Author(s) 2016. CC-BY 3.0 License.