Modelling of Thermal and Energy Systems Research Group

Design and evaluation of descarbonisation strategies to achieve near zero emissions indoor swimming pools assisted by renewable energies - nZEPools (2022-2025)

This is a project funded by the Ministry of Science and Innovation, Spain and the support of the European Regional Development Fund and NextGenerationEU Fund (TED2021-131173B-I00).

The objective of this proposal is to develop and show in a pilot project, the performances of a CO2 heat pump prototype able to provide thermal energy at different temperature levels swimming pool heating (27ºC), direct hot water for the changing rooms (60ºC), and if possible room-heating (70ºC) assisted by a photovoltaic enerergy system to satisfy the 30% of the annual thermal energy demand of an indoor swimming pool that could complement the 75% provided by a solar thermal system to reach a nZEPool. This also seeks to develop a numerical model that coupled with the pool demand could evaluate de performance of the solution under different operative and climatic conditions. It is expected to be validated by means of the data obtained in the pilot plant. Other objectives are:

• Analyse theoretically different types of heat pumps configurations using CO2 and/or other refrigerants of type A1 and with low GWP and select the most efficient solution to provide the different levels of hot water temperature required.

• Build a prototype of the HP solution proposed. Initially model it by developing a numerical dynamic model in TRNSYS to simulate the thermal and energy performance of the heat pump alone and coupled with the solar thermal system, a photovoltaic facility and a possible hot-water storage under different conditions.

• Optimise the hot-water storage tank with new water filling strategies depending on the demand profile (maximum energy storage vs maximum stratification) to maximize the system COP.

• Perform a Pilot Project. Operation the heat pump prototype in the indoor swimming pool of La Aljorra, which belongs to the Cartagena Municipality. This pool already has a solar thermal energy installation.

• Validation and evaluation of the sustainability of the solution by means of carbon footprint evaluation, energy selfsufficiency and profitability analysis.

For disemmination purposes, several deliverables were forseen:

• Deliverable 1. Report on the theoretical evaluation, by means of simple numerical models, of the use of different heat pumps configurations and refrigerants type A1 with low GWP in order to select the most efficient option to provide the different levels of hot water temperature required ( d1.pdf ).

• Deliverable 2. Description of the numerical dynamic model devoloped in TRNSYS to simulate the thermal and energy performance of the heat pump working alone, in the swimming pool, and coupled with a solar photovoltaic plant ( d2.pdf).

• Deliverable 3. Report on the optimisation of the hot-water storage tank with new water filling strategies depending on the indoor swimming pool demand profile (maximum energy storage vs maximum stratification) to maximise the system COP).

• Deliverable 4. Description of the prototype installed in the swimming pool (d4.pdf).

• Deliverable 5. Report evaluating the sustainability of the solution adopted by means of carbon footprint evaluation, energy self-sufficiency and profitability analysis. Providing GHGE and energy savings.

A webinar is going to be developed at the end of the project showing the main outcomes of this.