Thermal and physical characteristics of soils in Cyprus for use in shallow geothermal energy applications

Ramos, Robert Sala; Aresti, Lazaros; Yiannoukos, Loukas; Tsiolakis, Efthymios; Pekris, Joseph; Vieira, A.; Florides, Georgios A.; Christodoulides, Paul

doi:10.1007/s40974-019-00137-2

Cited by 6 publications

(5 citation statements)

References 24 publications

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“…This selection is based on the fact that the highest loads are observed during those months. Furthermore, the ground characteristics of the case study in Lefkosia are considered [51]. The ground examined consisted of marl, chalk, and gravel, with the complete model material properties described in Table 5.…”

Section: Energy Pilesmentioning

confidence: 99%

Residential Buildings’ Foundations as a Ground Heat Exchanger and Comparison among Different Types in a Moderate Climate Country

et al. 2020

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Shallow Geothermal Energy Systems (SGESs) constitute Renewable Energy Systems (RES), which find application in the residential sector through the use of Ground Source Heat Pumps (GSHPs). GSHPs are associated with Ground Heat Exchangers (GHEs), whereby heat is gained/lost through a network of tubes into the ground. GSHPs have failed to flourish in the RES market due to their high initial costs and long payback periods. In this study, the use of Energy Geo-Structure (EGS) systems, namely, the foundation (or energy) piles and the foundation bed of a residential building in Cyprus, was computationally modeled in the COMSOL Multiphysics software. First, the single-houses’ trend in number of units and area in Cyprus was examined and a theoretically typical house with nearly Zero Energy Building (nZEB) characteristics was considered. The heating and cooling loads were estimated in the TRNSYS software environment and used as inputs to investigate the performance of the GSHP/GHE systems. Both systems were shown to exhibit steady performance and high Coefficient of Performance (COP) values, making them an alternative RES solution for residential building integration. Next, the systems were economically evaluated through a comparison with a convectional Air Source Heat Pump (ASHP) system. The economic analysis showed that the cost of the suggested conversions of the foundation elements into GHEs had short payback periods. Consequently, either using the foundation piles or bed as a GHE is a profitable investment and an alternative to conventional RES.

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Section: Energy Pilesmentioning

confidence: 99%

Residential Buildings’ Foundations as a Ground Heat Exchanger and Comparison among Different Types in a Moderate Climate Country

et al. 2020

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“…In PVT systems using shallow soil layers, special attention should be paid to the thermophysical properties of the soil being used. The most important of these properties are the soil’s heat capacity, thermal conductivity, thermal diffusion, water content, and soil permeability . Furthermore, these properties are formed depending on the soil material origin, the climate of the region, and the soil moisture .…”

Section: Introductionmentioning

confidence: 99%

“…The most important of these properties are the soil’s heat capacity, thermal conductivity, thermal diffusion, water content, and soil permeability. 23 Furthermore, these properties are formed depending on the soil material origin, the climate of the region, and the soil moisture. 24 Finding these parameters greatly affects the design of geothermal energy pumps as well as soil-cooled PVT systems.…”

Section: Introductionmentioning

confidence: 99%

Cooling of a PVT System Using an Underground Heat Exchanger: An Experimental Study

Majeed,

Abdul-Zahra,

Mutasher

et al. 2023

ACS Omega

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In the recent decades, the researchers have been focused on the use of photovoltaic thermal (PVT) systems that provide the best performance and cooling for the photovoltaic panels. In this study, a PVT system consisting of a monocrystalline PV panel and a spiral heat exchanger was connected to an underground heat exchanger that is buried at a depth of 4 m below the surface of the earth. The procedure of the current study can be considered the first of its kind in the Middle East and North Africa region (based on the researchers' knowledge). The study was carried out on agricultural land in Baghdad-Iraq during months of July and August-2022, which are considered the harshest weather conditions for this city. The heat exchanger consists of a copper tube with a length of 21 m and formed in the shape of 3U, and it was buried in the earth and connected with a PVT system. The results of the study showed that the site chosen to bury the heat exchanger (4 m deep) has a stable soil temperature at 22.5 °C. From various volumetric flow rates, a flow rate of 0.18 l/s was selected which is considered the highest flow rate that can show vibration in the PVT system which may harm the system. The practical measurements showed that the largest difference in the surface temperatures of standalone PV and PVT was around 20 °C in favor of the latter. The electrical efficiency of the studied PVT system also increased to outperform the standalone PV system by 127.3%. By comparing the results of the current study with studies of water-cooled PVT systems from the literature, it is clear that the proposed system is feasible and has an acceptable efficiency in such harsh weather conditions tested during the experiment.

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“…Pebble beds have gained considerable traction in recent years for thermal storage and energy systems (Figure ). A breadth of benefits can be gained by using solid pebble beds for photovoltaics, wind energy, and nuclear energy storage systems, including reduced cost, increased safety, and operable working temperatures compared to liquid heat storage systems. − In addition, advanced next-generation pebble bed reactors (PBRs) have been highly rated for their safety and thermal efficiencies. − PBRs provide the option of being gas-cooled or molten salt-cooled, which can further increase their performance. , Pebble bed scenarios are also important for geothermal applications where discerning thermal properties is critical for efficiency in energy conversion, sustainability, environmental impact, economic viability, and structural performance. , In any case, developing models and measurement techniques for thermal properties and accurately depicting thermal transport in these pebble beds is crucial for their continued advancement (Table ).…”

Section: Introductionmentioning

confidence: 99%

“…6,8 Pebble bed scenarios are also important for geothermal applications where discerning thermal properties is critical for efficiency in energy conversion, sustainability, environmental impact, economic viability, and structural performance. 9,10 In any case, developing models and measurement techniques for thermal properties and accurately depicting thermal transport in these pebble beds is crucial for their continued advancement (Table 1).…”

Section: ■ Introductionmentioning

confidence: 99%

Analysis of Near-Wall Pebble Bed Thermal Conductivity for Energy Applications

Wada,

Eixenberger,

Stout

et al. 2023

ACS Omega

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Pebble beds have been employed in thermal storage and energy systems, where they are typically used to promote heat exchange in high-temperature environments. Understanding the heat conduction of the entire pebble bed could aid in the material selection of the pebbles themselves and structural components, system design, and safety monitoring. However, the thermal conductivity of pebble beds can change significantly near geometric boundaries. Using a complex multilayer analytical model in conjunction with a line source probe, we found a substantial increase in the thermal conductivity of a sintered bauxite pebble bed in the near-wall region (7.6 W m −1 K −1 ) compared to the bulk (0.59 W m −1 K −1 ). We investigated this difference by comparing porosity results, acquired with micro-CT, of 33.18 and 33.31% at approximately one pebble width surrounding the probe (near-wall) and the bulk of the pebble bed, suggesting that the thermal conductivity is largely altered by thermal contact resistance in the nearwall regime.

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Thermal and physical characteristics of soils in Cyprus for use in shallow geothermal energy applications

Cited by 6 publications

References 24 publications

Residential Buildings’ Foundations as a Ground Heat Exchanger and Comparison among Different Types in a Moderate Climate Country

Residential Buildings’ Foundations as a Ground Heat Exchanger and Comparison among Different Types in a Moderate Climate Country

Cooling of a PVT System Using an Underground Heat Exchanger: An Experimental Study

Analysis of Near-Wall Pebble Bed Thermal Conductivity for Energy Applications

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