Toward a Sustainable Indoor Environment: Coupling Geothermal Cooling with Water Recovery Through EAHX Systems

Cristina Baglivo, Alessandro Buscemi, Michele Spagnolo, Marina Bonomolo, Valerio Lo Brano () and Paolo Maria Congedo
Additional contact information
Cristina Baglivo: Department of Engineering for Innovation, University of Salento, 73100 Lecce, Italy
Alessandro Buscemi: Department of Engineering, University of Palermo, 90128 Palermo, Italy
Michele Spagnolo: Department of Engineering for Innovation, University of Salento, 73100 Lecce, Italy
Marina Bonomolo: Department of Engineering, University of Palermo, 90128 Palermo, Italy
Valerio Lo Brano: Department of Engineering, University of Palermo, 90128 Palermo, Italy
Paolo Maria Congedo: Department of Engineering for Innovation, University of Salento, 73100 Lecce, Italy

Energies, 2025, vol. 18, issue 9, 1-19

Abstract: This study presents a preliminary analysis of an innovative system that combines indoor air conditioning with water recovery and storage. The device integrates Peltier cells with a horizontal Earth-to-Air Heat Exchanger (EAHX), exploiting the ground stable temperature to enhance cooling and promote condensation. Warm, humid air is pre-cooled via the geothermal pipe, then split by a fan into two streams: one passes over the cold side of the Peltier cells for cooling and dehumidification, while the other flows over the hot side and heats up. The two airstreams are then mixed in a water storage tank, which also serves as a thermal mixing chamber to regulate the final air temperature. The analysis investigates the influence of soil thermal conditions on condensation within the horizontal pipe and the resulting cooling effect in indoor spaces. A hybrid simulation approach was adopted, coupling a 3D model implemented in COMSOL Multiphysics ® with a 1D analytical model. Boundary conditions and meteorological data were based on the Typical Meteorological Year (TMY) for Palermo. Two scenarios were considered. In Case A, during the hours when air conditioning is not operating (between 11 p.m. and 9 a.m.), air is circulated in the exchanger to pre-cool the ground and the air leaving the exchanger is rejected into the environment. In Case B, the no air is not circulated in the heat exchanger during non-conditioning periods. Results from the June–August period show that the EAHXs reduced the average outdoor air temperature from 27.81 °C to 25.45 °C, with relative humidity rising from 58.2% to 66.66%, while maintaining nearly constant specific humidity. The system exchanged average powers of 102 W (Case A) and 96 W (Case B), corresponding to energy removals of 225 kWh and 212 kWh, respectively. Case A, which included nighttime soil pre-cooling, showed a 6% increase in efficiency. Condensation water production values range from around 0.005 g/s with one Peltier cell to almost 0.5 g/s with seven Peltier cells. As the number of Peltier cells increases, the cooling effect becomes more pronounced, reducing the output temperature considerably. This solution is scalable and well-suited for implementation in developing countries, where it can be efficiently powered by stand-alone photovoltaic systems.

Keywords: earth-to-air heat exchanger system (EAHXs); peltier cells; geothermal cooling; finite element method (FEM) (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2025
References: Add references at CitEc
Citations:

Downloads: (external link)
https://www.mdpi.com/1996-1073/18/9/2297/pdf (application/pdf)
https://www.mdpi.com/1996-1073/18/9/2297/ (text/html)

Related works:
This item may be available elsewhere in EconPapers: Search for items with the same title.

Export reference: BibTeX RIS (EndNote, ProCite, RefMan) HTML/Text

Persistent link: https://EconPapers.repec.org/RePEc:gam:jeners:v:18:y:2025:i:9:p:2297-:d:1646600

Access Statistics for this article

Energies is currently edited by Ms. Agatha Cao

More articles in Energies from MDPI
Bibliographic data for series maintained by MDPI Indexing Manager ().