Spatiotemporal variability of ground thermal properties in glacial sediments and implications for horizontal ground heat exchanger design

Shawn Naylor, Kevin M. Ellett and Andrew R. Gustin

Renewable Energy, 2015, vol. 81, issue C, 21-30

Abstract: Thorough characterization of the spatiotemporal variability in soil thermal properties can facilitate better designs for horizontal geothermal heat pump (HGHP) systems by reducing ground heat exchanger (GHEX) costs. Results are presented from a new monitoring network installed across a range of glaciated terrains in Indiana (USA), including the first known observations of the dynamic range of thermal conductivity that occurs at the depth of horizontal GHEX installations. In situ thermal conductivity data can vary significantly on a seasonal basis in coarse-grained outwash sediments (0.8–1.4 W m−1 K−1), whereas clay- and silt-dominated moraine sediments have a dampened seasonal range within 10% of the annual mean. Thermal conductivity across the network ranges from 0.8 to 2.0 W m−1 K−1 depending on soil parent material, climatic setting, and particularly, soil-moisture variability. Results indicate that the standard industry practice to estimate thermal properties from soil type often leads to suboptimal GHEX design (i.e., GHEX design lengths were 44–52% longer than necessary to meet performance specifications). This research suggests that expanding the characterization of soil thermal properties in specific settings where HGHPs are targeted will improve understanding of the dynamic aspects of ground heat exchange and lead to more optimal HGHP system designs.

Keywords: Soil thermal properties; Geothermal heat pump; Thermal conductivity; Ground temperature; Soil moisture (search for similar items in EconPapers)
Date: 2015
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (14)

Downloads: (external link)
http://www.sciencedirect.com/science/article/pii/S0960148115001883
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:81:y:2015:i:c:p:21-30

DOI: 10.1016/j.renene.2015.03.006

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 ().