Geothermal energy in loess

Abstract

Ground-source heat pump (GSHP) systems efficiently heat and cool buildings by using sustainable geothermal energy accessed by way of ground heat exchangers (GHEs). Loess covers vast parts of the world, about 10% of the landmass; therefore, the use of piles or 'micropiles' is extensive in these areas, particularly where the thickness of loessic soils is significant. These deep foundations have the potential to be used as 'energy piles' in GSHP systems, with a minimal additional cost. This paper presents a case study of a representative real building in Córdoba, Argentina, where foundations are also used as GHEs. The thermal properties of local soils were experimentally measured and used in recently developed detailed state-of-the-art finite-element models. Results from the realistic simulations show that the partial substitution of electrical heating and cooling systems with geothermal systems could significantly reduce energy consumption and the size of associated infrastructure, despite the relatively low thermal conductivity of local loess. Moreover, the effects of surface air temperature fluctuations, which are routinely ignored in GHE design, are accounted for in these simulations. This case study shows the potential of GSHP technology in loessic environments and gives incentives to engineers to start considering the technology in their designs and practices.

Thermal Response Testing of Large Diameter Energy Piles

“…A validated transient numerical model developed at the University of Melbourne is used [51][52][53]. The model is built and solved using the finite element software package COMSOL Multiphysics.…”

Carrier fluid temperature data in vertical ground heat exchangers with a varying pipe separation

“…The data were generated using a validated finite element numerical methodology, and applied through the software COMSOL Multiphysics, which was developed at the University of Melbourne [2] , [3] , [4] . This methodology models the conduction and convection heat transfer processes taking place during the operation of a shallow geothermal system (see for example [5] , [6] for a detailed description of these systems).…”

Long-term thermo-mechanical behaviour of energy piles in clay

“…In spite of various studies on the thermo-mechanical behaviour of energy piles, few works have investigated their long-term behaviour. Actually, to deal with this aspect, some studies investigated the mechanical behaviour of energy piles subjected to numerous thermal cycles, which represent the seasonal pile temperature variations (Ng et al, 2014;Pasten and Santamarina, 2014;Suryatriyastuti et al, 2014;Di Donna and Laloui, 2015;Olgun et al, 2015;Saggu and Chakraborty, 2015;Ng et al, 2016;Bidarmaghz et al, 2016;Vieira and Maranha, 2016;Nguyen et al, 2017). In these studies, numerical methods are usually used and experimental methods are mainly based on physical modelling.…”