Geothermal energy in the Vallbona de les Monges Monastery

The Monastery of Santa Maria de Vallbona, located in the Catalan region of Urgel, has Ecoforest geothermal heat pumps for the air conditioning of its rooms.

The production of DHW and the support of high temperature heating is possible thanks to two ecoGEO B4 5-22Kw HTR EH pumps, which have a total rated thermal power of 44 kW. Together with the power of the existing pumps, the output was increased to 170 kW.

OPERATION OF THE EQUIPMENT

The two Ecoforest pumps, linked together in parallel and electronically as master and slave, will work as one, allowing the power range to be modulated from 4 to 44 kW. The new unit will work for the production of hot water over the existing heat exchanger that heats the 1000 L DHW tank. Once the set point is reached, the existing 500 l hot water tank will be heated. Once the hot water has been heated, the machine can be used to support the heating system over the 500 l buffer tank in the geothermal room or to heat the air conditioning of the gothic rooms by heating the new 800 l buffer tank located underneath them in the collector room.

With the installation of the Ecoforest e-manager, the surplus photovoltaic energy is managed. In winter, if available, they are used for DHW production or heating support. In summer for DHW production and cooling of the gothic rooms, if there is a surplus, the 800 l buffer tank that feeds the fan coils in the gothic room is cooled to provide cooling.

COLLECTION SYSTEM

This is a collection circuit consisting of 19 wells of 125 ml with a double 32 mm probe.

According to the ground thermal response test (TRT) carried out in the first of the wells by the company Sialtec geotermia and following the German VDI regulations, the ground could extract a power of between 46.2 – 48.5 W/m if no water was found, as was the case in this first well. In the rest of the wells, where water was found and according to the same study, the power to be extracted could be between 51.5 – 53.4 W/m. In the most favourable case, observing the reaction of the wells over the two winters the installation has worked, the power that can be dissipated by the wells is 53.4 W/m, therefore 126,825 W. The temperature graphs of the wells during this time show that the temperature does not drop below 9ºC, which means that the real performance of the wells is higher than that calculated by the TRT carried out in the third phase.

If we increase the thermal demand by 44 kW, we obtain the simulation of temperatures in the wells over the next three years. With these simulations we can guarantee over 25 years that the ground is capable of dissipating the energy exchanged each year and with the parameters approximately the same as the initial ones. The following graph shows the temperatures of the wells over the next 3 years:

ENGINE ROOM

The engine room was designed to meet minimum safety requirements for people and the building in which it is located, as well as to facilitate maintenance and driving operations. In particular, the current regulations on fire protection conditions have been taken into account. In accordance with the provisions of the UNE 100020 standard, a ventilation system was installed.