Strength Tests of Hardened Cement Slurries for Energy Piles, with the Addition of Graphite and Graphene, in Terms of Increasing the Heat Transfer Efficiency

Śliwa, T.; Sapińska-Śliwa, Aneta; Wysogląd, Tomasz; Kowalski, T.; Konopka, Izabela

doi:10.3390/en14041190

Cited by 6 publications

(3 citation statements)

References 53 publications

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“…In addition, an enhanced conductivity of 3 Wm −1 K −1 for a mixture of bentonite with graphite (percentage not mentioned) was reported by Hellström et.al, 1998 [44]. Graphite and graphene have also been found to increase cement's thermal conductivity by more than 11% when added to cement slurry in an energy pile construction [45]. A 68% increase in cement slurry's thermal conductivity (from 0.69 to 1.17 Wm −1 K −1 ) was achieved by adding 45% magnesium powder [46].…”

Section: Grouting Materialsmentioning

confidence: 84%

A Critical Review on the Use of Shallow Geothermal Energy Systems for Heating and Cooling Purposes

Ahmed

Assadi

Mehrjerdi³

et al. 2022

Energies

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The reduction of CO2 emissions has become a global concern. In this regard, the EU intends to cut CO2 emissions by 55% by 2030 compared to those of 1990. The utilization of shallow geothermal energy (SGE) in EU countries is considered the most effective measure for decarbonizing heating and cooling. SGE systems utilize heat energy collected from the earth’s crust to provide secure, clean, and ubiquitous energy. This paper provides a literature review on the use of SGE for heating and cooling purposes. The latest advances in materials, new innovative structures, and techno-economic optimization approaches have been discussed in detail. Shallow geothermal energy’s potential is first introduced, and the innovative borehole structures to improve performance and reduce installation cost is outlined. This is followed by an extensive survey of different types of conventional and thermally enhanced collectors and grouts. Attention is mainly given to the techno-economic analysis and optimization approaches. In published case studies, the least economic break-even point against fossil fuel-based heating systems occurs within 2.5 to 17 years, depending on the local geological conditions, installation efficiency, energy prices, and subsidy. Ground source heat pumps’ cost-effectiveness could be improved through market maturity, increased efficiency, cheap electricity, and good subsidy programs.

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Section: Grouting Materialsmentioning

confidence: 84%

A Critical Review on the Use of Shallow Geothermal Energy Systems for Heating and Cooling Purposes

Ahmed

Assadi

Mehrjerdi³

et al. 2022

Energies

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“…As the axial constraint increased, the axial thermal stress of the energy pile in clay also increased. To improve the heat transfer effect, bearing capacity, and thermal storage properties of energy piles, many scholars [9][10][11] have started to prepare innovative high-performance concrete as pile materials.…”

Section: Introductionmentioning

confidence: 99%

Study on the thermal response of spiral energy piles based on field test

et al. 2023

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Field tests of spiral energy piles under the combined effect of temperature and loading are relatively few. Based on the field test, the heat transfer efficiency, pile strain, axial force and shaft friction of two spiral energy piles were studied. The major findings of the experimental studies were as follows: First, when the double spiral energy pile was heated, the temperature distribution was more uniform; the total heat transfer and the heat transfer rate were higher than those of the single spiral energy pile. Second, the pile strain distribution was such that smaller values were noticed at both pile ends while larger values were in the middle part of the pile. The additional tensile stresses of the two piles generated during cooling reached 4.06 MPa and 4.75 MPa, which exceeded the tensile strength of concrete. Finally, during heating, the shaft friction was negative in the middle and upper pile and positive in the middle and lower pile. The single spiral energy pile showed two neutral points. The downward load generated by the single spiral energy pile was about 885 kN higher than that generated by the double one. The above changes should be focused on in the actual project.

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“…The heat from the rock mass by means of borehole heat exchangers [10][11][12][13][14][15] or energy piles [16][17][18][19][20]; -Hot Dry Rocks (HDR systems) [21][22][23][24] and Enhanced Geothermal System (EGS) [21,[24][25][26]; -Salt domes [27,28]; -Water from drainage, e.g., underground or opencast mines [29][30][31]; -Closed mines [27,32]; -Waters accompanying the multi-phase exploitation of hydrocarbons [33].…”

Section: Introductionmentioning

confidence: 99%

Research on Fresh and Hardened Sealing Slurries with the Addition of Magnesium Regarding Thermal Conductivity for Energy Piles and Borehole Heat Exchangers

et al. 2021

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Currently, renewable energy is increasingly important in the energy sector. One of the so-called renewable energy sources is geothermal energy. The most popular solution implemented by both small and large customers is the consumption of low-temperature geothermal energy using borehole heat exchanger (BHE) systems assisted by geothermal heat pumps. Such an installation can operate regardless of geological conditions, which makes it extremely universal. Borehole heat exchangers are the most important elements of this system, as their design determines the efficiency of the entire heating or heating-and-cooling system. Filling/sealing slurry is amongst the crucial structural elements. In borehole exchangers, reaching the highest possible thermal conductivity of the cement slurry endeavors to improve heat transfer between the rock mass and the heat carrier. The article presents a proposed design for such a sealing slurry. Powdered magnesium was used as an additive to the cement. The approximate cost of powdered magnesium is PLN 70–90 per kg (EUR 15–20/kg). Six different slurry formulations were tested. Magnesium flakes were used in designs A, B, C, and magnesium shavings in D, E and F. The samples differed in the powdered magnesium content BWOC (by weight of cement). The parameters of fresh and hardened sealing slurries were tested, focusing mainly on the thermal conductivity parameter. The highest thermal conductivity values were obtained in design C with the 45% addition of magnesium flakes BWOC.

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Strength Tests of Hardened Cement Slurries for Energy Piles, with the Addition of Graphite and Graphene, in Terms of Increasing the Heat Transfer Efficiency

Cited by 6 publications

References 53 publications

A Critical Review on the Use of Shallow Geothermal Energy Systems for Heating and Cooling Purposes

A Critical Review on the Use of Shallow Geothermal Energy Systems for Heating and Cooling Purposes

Study on the thermal response of spiral energy piles based on field test

Research on Fresh and Hardened Sealing Slurries with the Addition of Magnesium Regarding Thermal Conductivity for Energy Piles and Borehole Heat Exchangers

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