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USING EGRT TO IMPROVE PERFORMANCE AND EFFICIENCY

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Over the last few months, GEOTER has been working on selecting the most suitable way to monitor underground temperature and the communication and connection systems as part of WP4: Concept and Impact Validation. It will enable us to know, with time, the evolution of the geothermal resources, according to the demand of the buildings. In this context, GEOTER have developed the Enhanced Geothermal Response Test (EGRT) based on usage of a new equipment setup for the realisation of an on-site thermal conductivity test and continuous monitoring of the geothermal probes. It will provide us with geothermal field sizing optimisation and provide us the necessary data oriented to the MPC controller to decide the thermal management of the buildings.

The main advantages of the EGRT against current tests are that we can obtain:

 

1-Depth-Temperature profile. 2-Information about the depth where the most efficient part will be regarding the performance of the geothermal probe. 3-Measuring the influence of the groundwater. 4-To get information about the regeneration process of the subsoil. 5-Information about the grouting process. 6-To get information about the change of the thermal conductivity of the geothermal field while the HVAC system of the building is working.

 

GEOTER has used the EGRT system in two different areas: Móstoles (Madrid, Spain) and in Madrid Barajas Airport. The first test was carried out during 21-24 March 2017 in a borehole 127 metres depth, and the second 23-26 January 2018 in a borehole 127 metres depth. These were executed with the aim of determine the total thermo-physical characterisation of the sub-soil. The interpretation of these EGRTs has allowed us to establish the effective thermal conductivity and thermal resistance of the boreholes. Following the analysis of all the data collected, we could know the thermal conductivity variation of the sub-soil along the depth of the probe, cm per cm.

 

The thermal conductivity describes the heat transference through the conductivity principle in the subsoil.  This will be influenced by the different existing layers along the lithological column and its water saturation content.  This information about conductivity along the complete geothermal probe through the EGRT allows us to make a very accurate calculation of the geothermal field with the performance of an energy simulation. It will simulate the thermal loads of the building that will be constructed along with the description of the complete HVAC production and distribution system that will be carried out.

 

Thus, we are convinced that the use of this data is of a great importance and we will be able to make a better-optimised geothermal capitation field because we have obtained a better understanding about the behaviour of the soil. The ability to monitor the evolution of the range of temperatures, the thermal conductivity and resistances in the boreholes remotely and continuously with this device reduces the possible problems of measurement and later studies.  Finally, this would also be a way to minimise cost, effort and time.