Cascade Use of Low Enthalpy Geothermal Water at the University of Oradea

Abstract

The geothermal well located in the campus of the University of Oradea has the following characteristics: well head temperature about 85°C, artesian flow rate about 30 l/s; pumped flow rate 55 l/s. Considering a reference temperature of 20°C, the available heating power is about 8 MWth. The university campus extended during the last years by the construction of new buildings (library, student hostels, gymnasium), and by the transfer to the university of some buildings previously used by the army. Given the need to supply, in the near future, also the thermal energy demand of the new buildings of the University of Oradea, the possibilities of cascading the use of the energy from geothermal water from this well has been analyzed. For a complete and efficient use of the energy available from geothermal water produced from the existing well, it is necessary to use a complex system that would allow exploitation of the thermal energy down to the lowest possible temperature of the geothermal water. The proposed system will provide space heating for some buildings using existing cast iron radiators requiring higher inlet temperature (3.685 kWth), the outflow being used for other buildings which will have floor heating (1.300 kWth), the outflow from which will further used for heat pumps to supply other buildings with floor heating (1.400 kWt). Sanitary hot water (750 kWth) will also be supplied. The last use, before disposal in the nearby stream, will be snow melting (700 kWt). Implementing this cascade system will increase use of the thermal energy available from the borehole and will decrease the cost, as the university is invoiced for the geothermal used water, not energy.