Long-term performance of a shallow borehole heat exchanger installed in a geothermal field of Alsace region

Fujiao Tang and Hossein Nowamooz

Renewable Energy, 2018, vol. 128, issue PA, 210-222

Abstract: Seasonal hydrothermal variations on the land surface affect temperature as well suction profile in soil at shallow zones. For a Shallow Borehole Heat Exchanger (SBHE) buried not deep enough in the unsaturated soil, neglecting seasonal metrological conditions on the land surface may lead to design errors that may result in losing public's confidence. In this paper, an appropriate hydrothermal numerical analysis is used to predict seasonal hydrothermal fluctuations and SBHE performance of a site with a multi-layered soil system. The capacity of the numerical model is initially validated by the measured data from the thermal and humidity probes instrumented in a field located at Illkirch in the Alsace region (France). The results illustrate that the soil hydraulic conditions, as well as the soil thermal properties depend highly on the unsaturated soil properties in different layers. Then, the model is used to explore the performance of a SBHE installed in the same place over a year considering two different scenarios: constant inlet temperature and seasonal heat load. It has been found that the heat pump Coefficient of Performance (COP) in constant inlet temperature scenario remains almost stable during the service period. While in the case of seasonal heat load scenario, heat pump COP depends strongly on heat load and shows more variance. Eventually, the performance of the SBHE is estimated for the 5-year period considering the constant inlet temperature scenario. It has been found that the yearly Total Extracted Energy (TEE) decreases annually, while this reduction becomes less significant after the fourth year. The phenomenon illustrates that the SBHE is capable of outputting stable energy after reaching the equilibrium stage.

Keywords: Shallow borehole heat exchanger; Hydrothermal properties; In-situ investigation; Numerical modeling (search for similar items in EconPapers)
Date: 2018
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (9)

Downloads: (external link)
http://www.sciencedirect.com/science/article/pii/S0960148118305949
Full text for ScienceDirect subscribers only

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:eee:renene:v:128:y:2018:i:pa:p:210-222

DOI: 10.1016/j.renene.2018.05.073

Access Statistics for this article

Renewable Energy is currently edited by Soteris A. Kalogirou and Paul Christodoulides

More articles in Renewable Energy from Elsevier
Bibliographic data for series maintained by Catherine Liu ().