Determination of ground thermal properties for energy piles by thermal response tests

Ground source heat pump (GSHP) systems exchange heat with the ground, often through a closed-loop, vertical, borehole heat exchanger (BHE). The performance of the BHE depends on the thermal properties of the ground formation, as well as soil or backfill in the borehole. The design and economic probability of GSHP systems need the thermal conductivity of geological structure and thermal resistance of BHE. Thermal response test (TRT) method allows the in-situ determination of the thermal conductivity (λ) of the ground formation in the vicinity of a BHE, as well as the effective thermal resistance (Rb) of this latter. Thermal properties measured in laboratory experiments do not comply with data of in-situ conditions. The present article describes the results of thermal properties of the BHE whose depth is 100m in Yancheng City, Jiangsu Province, China. As shown in these results, λ and Rb of borehole are determined as 1.84(W·m-1·K-1) and 0.121 (m·K·W-1) respectively.

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Determination of the thermal properties of leaves by non-invasive contact‑free laser probing

Journal of Biotechnology ◽

10.1016/j.jbiotec.2015.11.008 ◽

2016 ◽

Vol 217 ◽

pp. 100-108 ◽

Cited By ~ 13

Author(s):

J.F. Buyel ◽

H.M. Gruchow ◽

N. Tödter ◽

M. Wehner

Keyword(s):

Thermal Properties ◽

Non Invasive ◽

Laser Probing ◽

Contact Free

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Continental vs. Global Niche-Based Modelling of Freshwater Species’ Distributions: How Big Are the Differences in the Estimated Climate Change Effects?

Water ◽

10.3390/w13060816 ◽

2021 ◽

Vol 13 (6) ◽

pp. 816

Author(s):

Danijela Markovic ◽

Jörg Freyhof ◽

Oskar Kärcher

Keyword(s):

Climate Change ◽

Thermal Properties ◽

Safety Margin ◽

Thermal Response ◽

Future Climate Change ◽

Freshwater Species ◽

Response Curves ◽

Preferred Temperature ◽

Continental Scale ◽

Management Actions

Thermal response curves that depict the probability of occurrence along a thermal gradient are used to derive various species’ thermal properties and abilities to cope with warming. However, different thermal responses can be expected for different portions of a species range. We focus on differences in thermal response curves (TRCs) and thermal niche requirements for four freshwater fishes (Coregonus sardinella, Pungitius pungitius, Rutilus rutilus, Salvelinus alpinus) native to Europe at (1) the global and (2) European continental scale. European ranges captured only a portion of the global thermal range with major differences in the minimum (Tmin), maximum (Tmax) and average temperature (Tav) of the respective distributions. Further investigations of the model-derived preferred temperature (Tpref), warming tolerance (WT = Tmax − Tpref), safety margin (SM = Tpref − Tav) and the future climatic impact showed substantially differing results. All considered thermal properties either were under- or overestimated at the European level. Our results highlight that, although continental analyses have an impressive spatial extent, they might deliver misleading estimates of species thermal niches and future climate change impacts, if they do not cover the full species ranges. Studies and management actions should therefore favor whole global range distribution data for analyzing species responses to environmental gradients.

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Multidisciplinary Approaches for Assessing a High Temperature Borehole Thermal Energy Storage Facility at Linköping, Sweden

Energies ◽

10.3390/en14144379 ◽

2021 ◽

Vol 14 (14) ◽

pp. 4379

Author(s):

Max Hesselbrandt ◽

Mikael Erlström ◽

Daniel Sopher ◽

Jose Acuna

Keyword(s):

Thermal Properties ◽

High Temperature ◽

Energy Storage ◽

Thermal Energy ◽

Thermal Energy Storage ◽

Thermal Response ◽

Site Investigation ◽

Thermal Response Test ◽

Response Test ◽

Crystalline Bedrock

Assessing the optimal placement and design of a large-scale high temperature energy storage system in crystalline bedrock is a challenging task. This study applies and evaluates various methods and strategies for pre-site investigation for a potential high temperature borehole thermal energy storage (HT-BTES) system at Linköping in Sweden. The storage is required to shift approximately 70 GWh of excess heat generated from a waste incineration plant during the summer to the winter season. Ideally, the site for the HT-BTES system should be able to accommodate up to 1400 wells to 300 m depth. The presence of major fracture zones, high groundwater flow, anisotropic thermal properties, and thick Quaternary overburden are all factors that play an important role in the performance of an HT-BTES system. Inadequate input data to the modeling and design increases the risk of unsatisfactory performance, unwanted thermal impact on the surroundings, and suboptimal placement of the HT-BTES system, especially in a complex crystalline bedrock setting. Hence, it is crucial that the subsurface geological conditions and associated thermal properties are suitably characterized as part of pre-investigation work. In this study, we utilize a range of methods for pre-site investigation in the greater Distorp area, in the vicinity of Linköping. Ground geophysical methods, including magnetic and Very Low-Frequency (VLF) measurements, are collected across the study area together with outcrop observations and lab analysis on rock samples. Borehole investigations are conducted, including Thermal Response Test (TRT) and Distributed Thermal Response Test (DTRT) measurements, as well as geophysical wireline logging. Drone-based photogrammetry is also applied to characterize the fracture distribution and orientation in outcrops. In the case of the Distorp site, these methods have proven to give useful information to optimize the placement of the HT-BTES system and to inform design and modeling work. Furthermore, many of the methods applied in the study have proven to require only a fraction of the resources required to drill a single well, and hence, can be considered relatively efficient.

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