Analysis and study of different grouting materials in vertical geothermal closed-loop systems

Blázquez, Cristina Sáez; Martín, Arturo Farfán; Nieto, Ignacio Martín; García, Pedro Carrasco; Pérez, Luis Santiago Sánchez; González‐Aguilera, Diego

doi:10.1016/j.renene.2017.08.011

Cited by 46 publications

(14 citation statements)

References 23 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…A vertical borehole, consisting of a single-U polyethylene heat exchanger, a grouting high conductive material, and an external cylindrical polyethylene structure. The grouting material was selected from previous research results [29] and consisted of an aluminum cement, water, and silica sand mixture in portions of 25/25/50. Working fluid that eased the heat-exchange throughout the system.…”

Section: Description Of the Experimental Setupmentioning

confidence: 99%

Novel Experimental Device to Monitor the Ground Thermal Exchange in a Borehole Heat Exchanger

et al. 2020

Self Cite

View full text Add to dashboard Cite

Ground source heat pump (GSHP) systems are becoming popular in space heating and cooling applications. Despite this fact, in most countries, the role of this energy is not as important as it should be nowadays according to its capabilities for energy generation without CO2 emissions, mainly due to the lack of technical knowledge about GSHP performance. The analysis of the physical processes that take part in the geothermal exchanges is necessary to allow the optimal exploitation of the geothermal resources. For all the above, an experimental geothermal device was built in the laboratory to control the phenomena that take place in a borehole heat exchanger (BHE). A 1-m high single-U heat exchanger was inserted in the center of a polyethylene container which also included granular material (surrounding ground) and the grouting material. Temperature sensors were situated in different positions of the experimental setup. Physical processes are evaluated to finally validate the model. Numerous applications can be developed from the experimental BHE. In this research, the determination of the thermal conductivity of the material used as medium was carried out. Results of this parameter were also compared with the ones obtained from the use of the KD2 Pro device.

show abstract

Section: Description Of the Experimental Setupmentioning

confidence: 99%

Novel Experimental Device to Monitor the Ground Thermal Exchange in a Borehole Heat Exchanger

et al. 2020

Self Cite

View full text Add to dashboard Cite

show abstract

“…Additionally, they have a high thermal conductivity value, that is, they have an excellent capacity to conduce the heat. After preparing mixtures constituted by materials commonly used as grouts, some particular thermal and mechanical tests were carried out [29]. One of these tests, that stands out because of its importance is the measuring "in situ" of the thermal conductivity parameter [30,31].…”

Section: Grouting Materialsmentioning

confidence: 99%

Efficiency Analysis of the Main Components of a Vertical Closed-Loop System in a Borehole Heat Exchanger

et al. 2017

Self Cite

View full text Add to dashboard Cite

Abstract:In vertical closed-loop systems, it is common to use single or double U-tube heat exchangers separated by longitudinal spacers. In addition, the helical-shaped pipe is another configuration that requires lower drilling lengths but it is less used. The aim of the present research is to study the influence of these components on the total efficiency of a borehole heat exchanger (BHE). Thus, the differences between using single/double U-tubes (with or without spacers) and helical pipes are analysed in terms of efficiency. Through different laboratory tests, a small vertical closed-loop system was simulated in order to analyse all these possible configurations. The grouting materials and the temperatures of the ground were modified at the same time in these tests. Regarding the heat exchange process between the ground and the heat carrier fluid, it must be highlighted that the best results were obtained for the helical-shaped pipe configuration. Some of the improvements offered by this heat exchanger typology with respect to the vertical configuration is that a lower drilling depth is required even it requires a larger diameter. This leads to significant economic savings in the performing drilling process. Finally, it is also worth noting the importance of using spacers in vertical U-tubes and that no improvements have been found regarding the use of single or double configuration of U-tubes. Thanks to the laboratory results derived from this study it is possible to establish the optimum behaviour pattern for the entire vertical closed-loop systems.

show abstract

“…Given the depletion of fossil energy and the need to reduce the carbon footprint, interest in new and renewable energy techniques has increased worldwide. Of the various renewable energy systems currently available, ground source heat pump (GSHP) systems have been widely used because of their efficiency, energy conservation, and low-level emissions [1][2][3]. Worldwide, GSHP capacity increased 1.52-fold from 2010 to 2015 at a compound annual rate of 8.69% [4].…”

Section: Introductionmentioning

confidence: 99%

Optimizing the Design of a Vertical Ground Heat Exchanger: Measurement of the Thermal Properties of Bentonite-Based Grout and Numerical Analysis

Kim

2018

Sustainability

View full text Add to dashboard Cite

We prepared bentonite-based grouts for use in the construction of vertical ground heat exchangers (GHEs) using various proportions of silica sand as an additive, and measured the thermal conductivity (TC) and specific heat capacity (SHC) of the grouts under saturated conditions. Furthermore, we performed numerical simulations using the measured thermal properties to investigate the effects of grout-SHCs, the length of the high-density polyethylene (HDPE) pipe, the velocity of the working fluid, and the operation time and off-time during intermittent operation on performance. Experimentally, the grout TCs and SHCs were in the ranges 0.728–1.127 W/(mK) and 2519–3743 J/(kgK), respectively. As the proportions of bentonite and silica sand increased, the TC rose and the SHC fell. Simulation showed that, during intermittent operation, not only a high grout TC but also a high SHC improved GHE performance. Also, during both continuous and intermittent operation, GHE performance improved as the working fluid velocity increased, and there was a critical working fluid velocity that greatly affected the performance of the vertical GHE, regardless of operation mode, high-density polyethylene (HDPE) pipe length, or grout thermal properties; this value was 0.3 m/s. Finally, during intermittent operation, depending on the operation time and off-time, critical periods were evident when the ground temperature had been almost completely restored and any beneficial effect of intermittent operation had almost disappeared.

show abstract

Analysis and study of different grouting materials in vertical geothermal closed-loop systems

Cited by 46 publications

References 23 publications

Novel Experimental Device to Monitor the Ground Thermal Exchange in a Borehole Heat Exchanger

Novel Experimental Device to Monitor the Ground Thermal Exchange in a Borehole Heat Exchanger

Efficiency Analysis of the Main Components of a Vertical Closed-Loop System in a Borehole Heat Exchanger

Optimizing the Design of a Vertical Ground Heat Exchanger: Measurement of the Thermal Properties of Bentonite-Based Grout and Numerical Analysis

Contact Info

Product

Resources

About