Articoli di riviste: "Vertical ground heat exchanger"

1

Hu, Ying Ning, Ban Jun Peng, Shan Shan Hu e Jun Lin. "Experimental Study of Heating-Cooling Combined Ground Source Heat Pump System with Horizontal Ground Heat Exchanger". Advanced Materials Research 374-377 (ottobre 2011): 398–404. http://dx.doi.org/10.4028/www.scientific.net/amr.374-377.398.

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A hot-water and air-conditioning (HWAC) combined ground sourse heat pump(GSHP) system with horizontal ground heat exchanger self-designed and actualized was presented in this paper. The heat transfer performance for the heat exchanger of two different pipe arrangements, three layers and four layers, respectively, was compared. It showed that the heat exchange quantity per pipe length for the pipe arrangement of three layers and four layers are 18.0 W/m and 15.0 W/m. The coefficient of performance (COP) of unit and system could remain 4.8 and 4.2 as GSHP system for heating water, and the COP of heating and cooling combination are up to 8.5 and 7.5, respectively. The power consumption of hot-water in a whole year is 9.0 kwh/t. The economy and feasibility analysis on vertical and horizontal ground heat exchanger were made, which showed that the investment cost per heat exchange quantity of horizontal ground heat exchanger is 51.4% lower than that of the vertical ground heat exchanger, but the occupied area of the former is 7 times larger than the latter's.

2

Basok, Borys, Borys Davydenko, Hanna Koshlak e Volodymyr Novikov. "Free Convection and Heat Transfer in Porous Ground Massif during Ground Heat Exchanger Operation". Materials 15, n. 14 (12 luglio 2022): 4843. http://dx.doi.org/10.3390/ma15144843.

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Heat pumps are the ideal solution for powering new passive and low-energy buildings, as geothermal resources provide buildings with heat and electricity almost continuously throughout the year. Among geothermal technologies, heat pump systems with vertical well heat exchangers have been recognized as one of the most energy-efficient solutions for space heating and cooling in residential and commercial buildings. A large number of scientific studies have been devoted to the study of heat transfer in and around the ground heat exchanger. The vast majority of them were performed by numerical simulation of heat transfer processes in the soil massif–heat pump system. To analyze the efficiency of a ground heat exchanger, it is fundamentally important to take into account the main factors that can affect heat transfer processes in the soil and the external environment of vertical ground heat exchangers. In this work, numerical simulation methods were used to describe a mathematical model of heat transfer processes in a porous soil massif and a U-shaped vertical heat exchanger. The purpose of these studies is to determine the influence of the filtration properties of the soil as a porous medium on the performance characteristics of soil heat exchangers. To study these problems, numerical modeling of hydrodynamic processes and heat transfer in a soil massif was performed under the condition that the pores were filled only with liquid. The influence of the filtration properties of the soil as a porous medium on the characteristics of the operation of a soil heat exchanger was studied. The dependence of the energy characteristics of the operation of a soil heat exchanger and a heat pump on a medium with which the pores are filled, as well as on the porosity of the soil and the size of its particles, was determined.

3

Bertagnolio, Stephane, Michel Bernier e Michaël Kummert. "Comparing vertical ground heat exchanger models". Journal of Building Performance Simulation 5, n. 6 (novembre 2012): 369–83. http://dx.doi.org/10.1080/19401493.2011.652175.

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Huang, Xue Ting, Yan Ling Guan e Chao Jiang. "Research on the Initial Operating Performance of Ground Heat Exchangers". Applied Mechanics and Materials 448-453 (ottobre 2013): 2897–902. http://dx.doi.org/10.4028/www.scientific.net/amm.448-453.2897.

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Focus on the unfavorable effects of initial operation to the performance of ground heat exchangers, a three-dimensional CFD simulation of full-scale ground heat exchanger under dynamic load was established to investigate the heat transfer performance of a 120-meter vertical U-Tube ground heat exchanger under different initial operating time. The results show that initial operation has influence on the performance of ground heat exchangers.

5

Hanuszkiewicz-Drapała, Małgorzata, e Jan Składzień. "Heating system with vapour compressor heat pump and vertical U-tube ground heat exchanger". Archives of Thermodynamics 31, n. 4 (1 ottobre 2010): 93–110. http://dx.doi.org/10.2478/v10173-010-0031-8.

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Heating system with vapour compressor heat pump and vertical U-tube ground heat exchangerIn the paper a heating system with a vapour compressor heat pump and vertical U-tube ground heat exchanger for small residential house is considered. A mathematical model of the system: heated object - vapour compressor heat pump - ground heat exchanger is presented shortly. The system investigated is equipped, apart from the heat pump, with the additional conventional source of heat. The processes taking place in the analyzed system are of unsteady character. The model consists of three elements; the first containing the calculation model of the space to be heated, the second - the vertical U-tube ground heat exchanger with the adjoining area of the ground. The equations for the elements of vapour compressor heat pump form the third element of the general model. The period of one heating season is taken into consideration. The results of calculations for two variants of the ground heat exchanger are presented and compared. These results concern variable in time parameters at particular points of the system and energy consumption during the heating season. This paper presents the mutual influence of the ground heat exchanger subsystem, elements of vapour compressor heat pump and heated space.

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Tarrad, Ali H. "A 3-Dimensional Numerical Thermal Analysis for A Vertical Double U-Tube Ground-Coupled Heat Pump". International Journal of Chemical Engineering and Applications 12, n. 2 (giugno 2021): 12–16. http://dx.doi.org/10.18178/ijcea.2021.12.2.789.

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The ground heat exchanger plays a major role in the thermal performance and economic optimization of the ground-coupled heat pump. The present study focuses on the effect of the borehole size and the grout and soil thermal properties on the thermal assessment of these heat exchangers. A double U-tube heat exchanger was studied numerically by the COMSOL Multiphysics 5.4 software in a 3-dimensional discretization model. The double U-tube was circuited as a parallel flow arrangement and situated in a parallel configuration (PFPD) deep in the borehole. The grout and ground thermal conductivities were selected in the range of (0.73-2.0) W/m.K and (1.24-2.8) W/m.K respectively. The results revealed that the ground thermal conductivity showed a more pronounced influence on the thermal performance of the ground heat exchanger and with less extent for the grouting one. Increasing the grout filling thermal conductivity from (0.73) W/m.K to (2.0) W/m.K at a fixed ground thermal conductivity of (2.4) W/m.K has augmented the heat transfer rate by (10) %. The heat transfer rate of the ground heat exchanger exhibited marked enhancement as much as double when the ground thermal conductivity was increased from (1.24) W/m.K to (2.8) W/m.K at fixed grout thermal conductivity range of (0.78-2.0) W/m.K. It has been verified that increasing the borehole size has a negligible effect on the ground heat exchanger thermal performance when a grout with a high thermal conductivity was utilized in the ranged of examined configurations. The steady-state numerical analysis model outcomes of the present work could be implemented for the preliminary borehole design for a ground heat exchanger.

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Hu, Ping Fang, Zhong Yi Yu, Fei Lei, Na Zhu, Qi Ming Sun e Xu Dong Yuan. "Performance Evaluation of a Vertical U-Tube Ground Heat Exchanger Using a Numerical Simulation Approach". Advanced Materials Research 724-725 (agosto 2013): 909–15. http://dx.doi.org/10.4028/www.scientific.net/amr.724-725.909.

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A vertical U-tube ground heat exchanger can be utilized to exchange heat with the soil in ground source heat pump systems. The outlet temperature of the working fluid through the U-tube not only accounts for heat transfer capacity of a ground heat exchanger, but also greatly affects the operational efficiency of heat pump units, which is an important characteristic parameter of heat transfer process. It is quantified by defining a thermal effectiveness coefficient. The performance evaluation is performed with a three dimensional numerical model using a finite volume technique. A dynamic simulation was conducted to analyze the thermal effectiveness as a function of soil thermal properties, backfill material properties, separation distance between the two tube legs, borehole depth and flow velocity of the working fluid. The influence of important characteristic parameters on the heat transfer performance of vertical U-tube ground heat exchangers is investigated, which may provide the references for the design of ground source heat pump systems in practice.

8

Yang, Lian, Yong Hong Huang e Liu Zhang. "Study on Engineering Construction with Three-Dimensional Heat Transfer Modeling for Double U-Tube Heat Exchangers in Ground-Source Heat Pump Systems". Advanced Materials Research 700 (maggio 2013): 231–34. http://dx.doi.org/10.4028/www.scientific.net/amr.700.231.

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There are many ground source heat pumps in engineering construction application. However, Research on heat exchanger models of single-hole buried vertical ground source heat pump mostly focuses on single U-tube ground heat exchangers other than double U-tube ones in China currently. Compared with single U-tubes, double U-tubes have the heat transfer particularity of asymmetry. Therefore, the use of the traditional single tube models would have large error in the simulation of the actual double U-tube heat exchangers. This paper frames a three-dimensional heat transfer model for the vertical single-hole buried double u-tube heat exchanger in a ground source heat pump system. The model considers the performance of U-bube material and uses a dual coordinate system and makes the control elemental volumes superimposed.

9

Sagia, Zoi, Athina Stegou e Constantinos Rakopoulos. "Borehole Resistance and Heat Conduction Around Vertical Ground Heat Exchangers". Open Chemical Engineering Journal 6, n. 1 (4 maggio 2012): 32–40. http://dx.doi.org/10.2174/1874123101206010032.

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Borehole thermal resistance in Ground Heat Exchanger (GHE) installations is affected by several parameters such as geometrical attributes of heat exchanger in the borehole, pipes' characteristics and grout’s thermal conductivity. A study is carried out to compare the values computed by Ground Loop Design (GLD) Software, GLD 2009, with three ana-lytical solutions for U-shaped tubes. The analysis is focused on dimensionless ratios of borehole geometrical parameters (borehole diameter to outside pipe diameter and shank spacing to borehole diameter) and pipes according to Standard Di-mension Ratio (SDR) and on eight common grouts. Finally, the effect of heat conduction in the borehole is examined by means of finite element analysis by Heat Transfer Module of COMSOL Multiphysics. A two-dimensional (2-D) steady-state simulation is done assuming working fluid temperatures for winter and summer conditions and typical Greek undis-turbed ground temperature in a field of four ground vertical U-tube heat exchangers surrounded by infinite ground. The temperature profile is presented and the total conductive heat flux from the pipe to the borehole wall per meter of length of ground heat exchanger is computed for pipes SDR11 (the outside diameter of the pipe is 11 times the thickness of its wall), SDR9 and SDR17 for summer working conditions and three different configurations. It is attempted to reach to comparative results for borehole thermal resistance value through different types of analysis, having considered the major factors that affect it and giving trends for the influence of each factor to the magnitude of its value.

10

Zhang, Dan, Fa Hui Wang, Bo Lei, Yan Ping Yuan e Xiao Ling Cao. "Study on Heat Transfer Capacity Calculation of Multi-Hole Heat Source for Vertical U-Tube Ground Heat Exchangers". Applied Mechanics and Materials 71-78 (luglio 2011): 94–99. http://dx.doi.org/10.4028/www.scientific.net/amm.71-78.94.

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By studying the features of vertical u-tube ground heat exchangers, with the consideration of the mutual interference between heat exchanger wells on heat transfer, this thesis puts forward the numerical model and calculation method for the heat exchange study of the well group, on the basis of analyzing heat exchange for single well. The paper adopts a nine-well model which is convenient and represents the general patterns of the heat exchange between well groups. The amount of the heat exchange between well groups can be calculated through testing the heat exchange of the single well by means of the heat exchange correction coefficient.

11

Cadelano, Gianluca, Alessandro Bortolin, Eloisa Di Sipio, Giovanni Ferrarini, Paolo Bison, Adriana Bernardi, Giorgia Dalla Santa e Antonio Galgaro. "Laboratory assessment of corrosion rate of carbon steel ground heat exchangers". Advances in Geosciences 58 (11 novembre 2022): 41–46. http://dx.doi.org/10.5194/adgeo-58-41-2022.

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Abstract. The materials used in the manufacture of geothermal heat exchangers for shallow geothermal applications play an important role in the overall system performance, especially if grout is not being used to seal the boreholes in which the heat exchanger is installed. The subject of this study is the durability evaluation of a vertical coaxial ground heat exchanger made of steel that is coupled directly to the ground. This solution minimizes the thermal resistance between the heat exchanger and the ground, but presents the important drawback of removing any protection toward the surrounding environment Among the materials proposed for manufacturing such vertical geothermal heat exchanger, carbon steel is suitable and have potential, due to its low cost and high thermal conductivity. The main disadvantage of this material is that it is strongly subject to corrosive attack, according to the chemo-physical properties of the underground. This study investigated the corrosion behaviour of carbon steel used in an experimental underground heat exchanger and assessed its durability over time. Corrosion rate of steel samples were measured in the laboratory by weight loss method after exposure over a specified period in a selected ground medium. Different ground conditions were tested, resulting in different densities and moisture contents of ground samples collected on the field. Based on the results, the corrosion rate of carbon steel is evaluated as a function of water content and rate of ground compaction. This information has allowed to advance more accurate quantitative forecast of the expected operational life of installed geothermal exchangers and their safety over time.

12

Bezrodnyi, M. K., N. A. Prytula e M. A. Gobova. "OPTIMAL WORKING CONDITIONS OF THE GROUND SOURCE HEAT PUMP FOR HEAT SUPPLY". Energy Technologies & Resource Saving, n. 1 (20 marzo 2017): 19–26. http://dx.doi.org/10.33070/etars.1.2017.02.

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The method of determination of optimal working conditions of vertical ground heat exchanger for heat pump low temperature water heating system, providing minimum energy cost for heat production is presented in this article. It was determined that there is an optimum speed of a heat carrier to which minimum total cost of electricity for heating system in a whole corresponds when using vertical probes for heat pump heating system. The correlation between the characteristics of vertical ground heat exchanger (depth of the well, the intensity of selection of heat from the soil pipe diameter, the velocity of a heat carrier) in its optimal working conditions was found. It is shown that the optimum velocity of a heat carrier in the lower circuit depends on the depth of the well, the heat exchanger tube diameter, and is almost independent of temperature conditions works of heat pump systems. It is found that the higher velocity observed at the beginning of the heating period in view of energy storage in the ground. Optimum coolant velocity should decrease until the end of the heating season to ensure minimum specific energy expenditure at HPS. Also noted that an optimum velocity increases with increasing depth of the well and with decreasing diameter of the heat exchanger tube. The established correlation may be used when determining the optimum operating conditions of the vertical ground heat pump heat exchanger low-temperature heating systems with a plan to maximize their energy efficiency. Bibl. 8, Fig. 7.

13

Qi, Zi Shu, Qing Gao, Yan Liu, Y. Y. Yan e Jeffrey D. Spitler. "Analysis and Research on the Performance of the Ground Source Heat Pump System in Different Areas of China". Applied Mechanics and Materials 148-149 (dicembre 2011): 1137–40. http://dx.doi.org/10.4028/www.scientific.net/amm.148-149.1137.

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In the paper, it is to describe the performance of the vertical ground heat exchangers (GHE) in different areas of China. The energy consumption of ground source heat pump (GSHP) system is based on the instantaneous fluid temperature at the heat pump inlet. This temperature defines the GSHP coefficient of performance and hence the electricity consumption required in order to fulfill the energy demands of the building. A mathematical model for simulation of vertical ground heat exchanger system is built based on long time-step theory. The design methodology is based on a simulation that predicts the temperature response of the ground heat exchanger to hourly heating and cooling loads demand in 20 years. This paper presents GSHP system can achieve energy performance in buildings that heating and cooling loads all the year round in different areas.

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Cullin, J. R., J. D. Spitler, C. Montagud, F. Ruiz-Calvo, S. J. Rees, S. S. Naicker, P. Konečný e L. E. Southard. "Validation of vertical ground heat exchanger design methodologies". Science and Technology for the Built Environment 21, n. 2 (13 febbraio 2015): 137–49. http://dx.doi.org/10.1080/10789669.2014.974478.

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Kim, Kwonye, Jaemin Kim, Yujin Nam, Euyjoon Lee, Eunchul Kang e Evgueniy Entchev. "Analysis of Heat Exchange Rate for Low-Depth Modular Ground Heat Exchanger through Real-Scale Experiment". Energies 14, n. 7 (29 marzo 2021): 1893. http://dx.doi.org/10.3390/en14071893.

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A ground source heat pump system is a high-performance technology used for maintaining a stable underground temperature all year-round. However, the high costs for installation, such as for boring and drilling, is a drawback that prevents the system to be rapidly introduced into the market. This study proposes a modular ground heat exchanger (GHX) that can compensate for the disadvantages (such as high-boring/drilling costs) of the conventional vertical GHX. Through a real-scale experiment, a modular GHX was manufactured and buried at a depth of 4 m below ground level; the heat exchange rate and the change in underground temperatures during the GHX operation were tracked and calculated. The average heat exchanges rate was 78.98 W/m and 88.83 W/m during heating and cooling periods, respectively; the underground temperature decreased by 1.2 °C during heat extraction and increased by 4.4 °C during heat emission, with the heat pump (HP) working. The study showed that the modular GHX is a cost-effective alternative to the vertical GHX; further research is needed for application to actual small buildings.

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Shang, Shao Wen, Pei Pei Li e Dong Wen Fang. "Simulation Study on Heat Transferring Performance of Vertical T-Tube Ground Heat Exchangers". Advanced Materials Research 805-806 (settembre 2013): 547–51. http://dx.doi.org/10.4028/www.scientific.net/amr.805-806.547.

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In the Ground Source Heat Pump system, the vertical U-tube is the most common ground heat exchanger. The heat transfer between the U-tube and the soil is affected by many factors. For analyzing the influence of these factors on heat transfer of the U-tube, I use GAMBIT software to establish a physical model who is used to simulated the heat exchanging of single U-tube heat exchanger and the surrounding soil physical. and mesh it. On the base, we take advantage of FLUENT software to make numerical simulation. After finishing analysis, we got some conclusions as follows: Under different tube wells depths and different inlet water temperature conditions, with the pipe inlet velocity increases, the heat exchanger performance improves, but the temperature difference between the import and the export will decreases. In addition to improve the inlet temperature of the U-tube, we can significantly increase the transferring heat of the ground heat exchanger.

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Sutton, Matthew G., Darin W. Nutter e Rick J. Couvillion. "A Ground Resistance for Vertical Bore Heat Exchangers With Groundwater Flow". Journal of Energy Resources Technology 125, n. 3 (29 agosto 2003): 183–89. http://dx.doi.org/10.1115/1.1591203.

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A new ground resistance was developed for use in existing vertical bore heat exchanger VBHEx design algorithms. The new ground resistance accounts for the added heat transfer mode of convection due to groundwater flow by using as its foundation the solution for a moving line heat source. The combined ground resistance is presented in terms of the dimensionless Fourier and Peclet parameters. Results show that significant convection heat transfer may occur within a variety of hydrogeological regimes, particularly when the Peclet number is larger than 0.01. Since the new model captures the influence of groundwater flow, the resulting ground resistance differs markedly from the conduction-only ground resistance currently used in many vertical borehole heat exchanger design algorithms.

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Basok, B. I., B. V. Davydenko, V. G. Novikov, H. V. Koshlak e A. M. Pavlenko. "INFLUENCE OF SOIL FILTRATION PROPERTIES ON THE WORKING CHARACTERISTICS OF THE VERTICAL GROUND HEAT EXCHANGER". Thermophysics and Thermal Power Engineering 44, n. 1 (12 maggio 2022): 74–83. http://dx.doi.org/10.31472/ttpe.1.2022.9.

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Introduction. The purpose of these studies is to determine the effect of the filtration properties of soil as a porous medium on the performance of soil heat exchangers. Ground heat exchangers are important elements of heat pumps widely used to extract low potential heat from ground masses. In the over whelming majority of scientific works related to the numerical modeling of the operation of ground heat exchangers, the soil is considered as a continuous medium and heat transfer in it occurs only by thermal conductivity. In reality, soil is a porous medium, the pores of which can be filled with air and liquid. In this regard, in addition to thermal conductivity, heat transfer in the soil can also occur by convection of liquids or gas in a porous medium. Results. This paper presents the results of numerical modeling of the temperature regime of the soil U-tube heat exchanger, taking into account the free convective movement of the medium filling the pores of the soil. The system of equations describing this process consists of the equations of fluid dynamics in a porous medium and the energy equation. Attached to them is the heat transfer equation in a U-tube heat exchanger. Based on the results of solving this system of equations, the distributions of velocity and temperature in the porous soil medium, as well as the change in the temperature of the heating agent in the heat exchanger, are determined. It has been determined that the maximum velocity of the free convection flow of water in the pores under the observed conditions is of the order of ~ 10-6 m/s. Evaluation of the energy performance of the ground heat exchanger depending on the size of soil particles and its porosity showed that a larger volume of recoverable heat is provided with a smaller particle size and lower porosity. It is also shown that when the pores of the soil are filled with water, a larger volume of heat is extracted from the soil in comparison with the case of filling the pores with air.

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Bezrodny, M., e S. Oslovskyi. "THERMODYNAMIC EFFICIENCY OF HEAT PUMP AIR CONDITIONING SYSTEM BASED ON VERTICAL GROUND HEAT EXCHANGER". Energy and automation 2023, n. 3 (2023): 74–89. http://dx.doi.org/10.31548/energiya3(67).2023.074.

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An analysis of literary sources in which heat pump heating and air conditioning systems were studied over the past 10 years was carried out. It was determined that research for heat pumps using vertical soil heat exchangers was conducted more in the empirical plane. The authors analyzed the effectiveness of using existing systems that work for heating and air conditioning in different countries. The results of many studies are given, which show that, in fact, the use of ground heat pumps in a temperate climate only in the heating mode entails the exhaustion of the thermal potential and the impossibility of its use in the future. Theoretical studies at the system design stage are not sufficiently presented, and the issue of predictioning the efficiency of the use of such systems is not disclosed. In this regard, it is proposed to investigate the energy efficiency of the heat-pump air conditioning system based on vertical soil heat exchangers. A heat pump air conditioning system based on a vertical soil heat exchanger is considered. Two research tasks were defined: analysis of efficiency in active and passive modes of conditioning. A thermodynamic analysis of the efficiency of the proposed scheme was carried out. The main operating parameters of the system at nodal points are defined. With the help of balance equations, the framework of the system's operation in passive and active modes according to the main parameters is determined. Graphical dependences of energy efficiency indicators on the determining parameters of the system were constructed and analyzed. It is shown at which parameter values the system has optimal operating costs. The results of the study are compared with those for the split system. The advantages and disadvantages of using the proposed solution are determined. It was determined that the heat pump system using soil heat for air conditioning with a vertical soil heat exchanger has stricter requirements for the thermal insulation of the air conditioning object than the system based on the air heat pump.

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Jalaluddin, Akio Miyara, Rustan Tarakka e Muhammad Anis Ilahi Ramadhani. "Experimental Performance Analysis of Shallow Spiral-tube Ground Heat Exchangers in Series and Parallel Configurations". E3S Web of Conferences 130 (2019): 01017. http://dx.doi.org/10.1051/e3sconf/201913001017.

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Ground source cooling system (GSCS) uses a ground heat exchanger (GHE) for exchanging heat with the ground. A spiral-tube GHE is gaining interest in recent year. This study presents an experimental analysis of thermal performance of shallow spiral-tube ground heat exchanger (GHE) installed in the ground at 3 m depth in series and parallel configurations. These GHE configurations offer a compromise between the conventional vertical and horizontal GHEs. The spiral-tube GHE which is consist of spiral pipe installed in the borehole provides a better performance in application of GSCS. The thermal performances ofspiraltube GHE in series and parallel configurations were investigated under actual condition. Inlet and outlet temperatures of the both configurations were measured and periodically recorded. The average heat exchange rates of the GHEs are 122.4 W m –1 in parallel configuration and 86.2 W m –1in series configuration. Heat exchange rate of the spiral-tube GHEs in parallel configuration provides a better performance than that of in series configuration. The spiral-tube GHE in shallow depth can be applied in the GSCS.

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Zhu, Huiyuan. "Numerical simulation of temperature field around buried pipes of ground source heat pumps based on mathematical models". Thermal Science 28, n. 2 Part B (2024): 1441–48. http://dx.doi.org/10.2298/tsci2402441z.

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The author established a physical and mathematical model for the heat exchange of a ground source heat pump buried heat exchanger under the co-operation of heat and seepage, including the soil and fluid inside the pipe surrounding the heat exchanger. Using ANSYS finite element APDL language for programming, based on the line heat source model, simulate the temperature field around the vertical double U-tube underground heat exchanger, the effects of soil thermophysical properties, temperature outside the pipe, soil type and backfill material on soil temperature field were obtained through simulation analysis. The experimental results indicate that, the changes in soil temperature are also significant with different backfill materials. Therefore, it is necessary to conduct serious research and optimization on backfill materials, develop new types of backfill materials, improve backfill construction techniques, and conduct in-depth research by combining theoretical analysis with practical engineering to ultimately find efficient and economical backfill materials. The change in equivalent pipe diameter has little effect on soil temperature, and the linear heat source model is used for calculation without causing significant errors. It has been proven that the soil itself has strong resilience and has reference value for the design of buried heat exchangers in practical engineering.

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Lee, Chulho, Hujeong Gil, Hangseok Choi e Shin-Hyung Kang. "Numerical characterization of heat transfer in closed-loop vertical ground heat exchanger". Science in China Series E: Technological Sciences 53, n. 1 (gennaio 2010): 111–16. http://dx.doi.org/10.1007/s11431-009-0414-8.

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Jaundālders, S., P. Stanka e D. Rusovs. "Seasonal performance for Heat pump with vertical ground heat exchanger in Riga". IOP Conference Series: Materials Science and Engineering 251 (ottobre 2017): 012057. http://dx.doi.org/10.1088/1757-899x/251/1/012057.

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Rynkowski, Piotr. "The Solar-Assisted Vertical Ground Source Heat Pump System in Cold Climates—A Case Study". Proceedings 51, n. 1 (5 agosto 2020): 24. http://dx.doi.org/10.3390/proceedings2020051024.

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In this paper, experimental studies were performed for a solar ground source heat pump system (SGSHPS) with a vertical ground heat exchanger (VGHE). The experiment was operated during the summer in 2018. The heat from the solar collector was monitored by measuring the inlet and outlet temperatures and flow rate of the heat transfer fluids. An energy equilibrium balance carried out indicates heat extraction from the solar collector to the ground heat exchanger. It has been established that clear impact is achieved within a radius of 5 m. The average temperature of the actively regenerated borehole was higher than that of the undisturbed profile, which has a direct impact on the significant benefits of the coefficient of performance (COP) of the ground source heat pump system (GSHPS) and effectively helps soil regeneration. The average efficiency ratio of the heat transferred from solar radiation to soil in the SGSHPS was 42.3%.

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Du, Zhen Yu. "Simulation of Temperature Field of Soil Inside Drilling around a Vertically Buried Single-U-Tube Ground Heat Exchanger". Advanced Materials Research 393-395 (novembre 2011): 943–46. http://dx.doi.org/10.4028/www.scientific.net/amr.393-395.943.

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In this paper, the mathematical physical model of the heat and moisture transfer, which is about a vertical single-U-tube heat exchanger of a ground source heat pump (GSHP), is used to simulate the soil temperature fields inside drilling around a vertical single-U-tube ground source heat exchanger. The soil temperature fields inside drilling in the GSHP project running for one year are computed numerically. It shows that soil structure, cooling and heating load, cooling and heating period, and convalescence period have been determined by practical engineering conditions, the distance in the plane between drillings have a huge influence on heat transfer effect, only when the distance is designed reasonably, can it be possible to make sure normal heat transfer efficiency.

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Liang, Shao Qing. "Ground Source Heat Pump Air Conditioning System of Vertical Geothermal Heat Exchangers Heat Transfer Process and Design Calculation Method". Applied Mechanics and Materials 291-294 (febbraio 2013): 1728–34. http://dx.doi.org/10.4028/www.scientific.net/amm.291-294.1728.

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Geothermal heat exchanger is an important part of the GSHP air-conditioning system and different from other traditional air-conditioning systems. This article through to the geothermal heat exchanger heat transfer performance analysis and the design, derived from the geothermal heat exchanger length calculation formula, for actual engineering construction to provide a scientific basis.

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Álvarez Gómez, Pascual, Ismael Rodríguez Maestre, F. Javier González Gallero e J. Daniel Mena Baladés. "The Influence of Outer Weather Conditions on the Modelling of Vertical Ground Heat Exchangers". Applied Mechanics and Materials 361-363 (agosto 2013): 276–80. http://dx.doi.org/10.4028/www.scientific.net/amm.361-363.276.

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Policies for energy saving and carbon dioxide emission reduction have enouraged the use of efficient technologies in building thermal conditioning, like geothermal source heat pumps [. Most of the thermal models used to simulate the performance of vertical ground heat exchangers do not consider the effect of outer weather conditions, except for the setting of the initial ground temperature [. This paper shows a study to assess the effect of outer weather conditions on the outlet fluid temperature, especially during the upper part of the exchanger. Different depths for typical configurations of ground heat exchangers have been analysed. Detailed simulations have been developed for a full year of performance using a commercial finite volume computational fluid dynamics (CFD) code (©ANSYS-CFX). Outer weather conditions have been set by using synthetic hourly weather data and considering all of the heat transfer phenomena involved. Errors in outlet fluid temperature and surface borehole temperature have been estimated for the whole year of simulation.

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Eswiasi, Adel, e Phalguni Mukhopadhyaya. "Performance of Conventional and Innovative Single U-Tube Pipe Configuration in Vertical Ground Heat Exchanger (VGHE)". Sustainability 13, n. 11 (4 giugno 2021): 6384. http://dx.doi.org/10.3390/su13116384.

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A ground source heat pump system (GSHP) with a ground heat exchanger (GHE) is a renewable and green technology used for heating and cooling residential and commercial buildings. An innovative U-Tube pipe configuration is suggested to enhance the heat transfer rate in the vertical ground heat exchanger (VGHE). Laboratory experiments are conducted to compare the thermal efficiency of VGHEs with two different pipe configurations: (1) an innovative U-Tube pipe configuration (single U-Tube with two outer fins) and (2) a single U-Tube. The results show that the difference between the inlet and outlet temperatures for the innovative U-Tube pipe configuration was 0.7 °C after 60 h, while it was 0.4 °C for the single U-Tube after the same amount of time. The borehole thermal resistance for the innovative U-Tube pipe configuration was 0.680 m·K/W, which is 29.22% lower than that of the single U-Tube. The heat exchange rate in the innovative U-Tube pipe configuration is increased by 57.95% compared to the conventional single U-Tube. Measured ground temperatures indicate that compared to single U-Tube pipe configuration, the innovative U-Tube pipe configuration has superior heat transfer performance. Based on the experimental results presented in this paper, it was concluded that increasing the surface area significantly by introducing external fins to the U-Tube enhances the heat transfer rate, resulting in increased thermal efficiency of the VGHE.

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Gao, Yi Ke, Yan Gao, Yong Yu e Xin Xing Lin. "Numerical Simulation and Experimental Validation of a Vertical U-Tube Ground Heat Exchanger". Advanced Materials Research 860-863 (dicembre 2013): 709–14. http://dx.doi.org/10.4028/www.scientific.net/amr.860-863.709.

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Vertical U-tube ground heat exchanger (GHE) is a key component in geothermal energy utilization systems like ground source heat pump (GSHP). This paper used a two-dimensional transient mathematical model for predicting the heat extraction rate of a vertical U-tube GHE, which also took into account the temperature distribution under the ground. Furthermore the modelling predictions were validated using experimental data. The experimental validation on the model was performed in a GSHP system with a double U-tube GHE, which was of 55m depth. For temperature distribution under the ground, the absolute error and relative error between experiment and simulation are within 0.62°C and 3.71 %. Simulation results agreed well with the experimental results that validate the feasibility of the mathematical model.

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Sailer, Eleonora, David M. G. Taborda, Lidija Zdravkovic e David M. Potts. "Assessing the impact of vertical heat exchangers on the response of a retaining wall". E3S Web of Conferences 92 (2019): 16001. http://dx.doi.org/10.1051/e3sconf/20199216001.

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Shallow geothermal energy systems, e.g. borehole heat exchangers or thermo-active structures, provide sustainable space heating and cooling by exchanging heat with the ground. When installed within densely built urban environments, the thermo-hydro-mechanical (THM) interactions occurring due to changes in ground temperature, such as soil deformation and development of excess pore water pressures, may affect the mechanical behaviour of adjacent underground structures. This paper investigates the effects of vertical heat exchangers installed near a deep basement by performing fully coupled THM finite element analyses using the Imperial College Finite Element Program. Different heat exchanger configurations are considered and their influence on the response of the basement wall is assessed in two-dimensional plane strain analyses, where different methods of modelling the heat sources in this type of analysis are employed to evaluate their effect on the temperature field and the non-isothermal soil response.

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Koohi-Fayegh, Seama, e Marc A. Rosen. "Modeling of vertical ground heat exchangers". International Journal of Green Energy 18, n. 7 (24 marzo 2021): 755–74. http://dx.doi.org/10.1080/15435075.2021.1880913.

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32

Boban, Luka, Dino Miše, Stjepan Herceg e Vladimir Soldo. "Application and Design Aspects of Ground Heat Exchangers". Energies 14, n. 8 (11 aprile 2021): 2134. http://dx.doi.org/10.3390/en14082134.

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With the constant increase in energy demand, using renewable energy has become a priority. Geothermal energy is a widely available, constant source of renewable energy that has shown great potential as an alternative source of energy in achieving global energy sustainability and environment protection. When exploiting geothermal energy, whether is for heating or cooling buildings or generating electricity, a ground heat exchanger (GHE) is the most important component, whose performance can be easily improved by following the latest design aspects. This article focuses on the application of different types of GHEs with attention directed to deep vertical borehole heat exchangers and direct expansion systems, which were not dealt with in detail in recent reviews. The article gives a review of the most recent advances in design aspects of GHE, namely pipe arrangement, materials, and working fluids. The influence of the main design parameters on the performance of horizontal, vertical, and shallow GHEs is discussed together with commonly used performance indicators for the evaluation of GHE. A survey of the available literature shows that thermal performance is mostly a point of interest, while hydraulic and/or economic performance is often not addressed, potentially resulting in non-optimal GHE design.

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Yu, Ming Zhi, Lei Zhang, Xiao Fei Yu e Zhao Hong Fang. "Numerical Heat Transfer Model of Buried Pipe and Ground Thermal Conductivity Measurement". Applied Mechanics and Materials 99-100 (settembre 2011): 112–15. http://dx.doi.org/10.4028/www.scientific.net/amm.99-100.112.

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A two dimensional numerical heat transfer model of buried geothermal heat exchanger has been established by finite element method. This model is used to analyse the heat transfer between buried vertical pipes and the ground, and determine the ground thermal properties together with parameters estimation method. The ground thermal conductivity of an actual project was measured and the analysis shows that the results can be used for engineering design.

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Javed, Saqib, e Jeffrey D. Spitler. "Vertical ground heat exchanger pressure loss – Experimental comparisons and calculation procedures". Geothermics 105 (novembre 2022): 102546. http://dx.doi.org/10.1016/j.geothermics.2022.102546.

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35

Beauchamp, B., L. Lamarche e S. Kajl. "A dynamic model of a vertical direct expansion ground heat exchanger". Renewable Energy and Power Quality Journal 1, n. 06 (marzo 2008): 545–51. http://dx.doi.org/10.24084/repqj06.364.

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Beier, Richard A. "Vertical temperature profile in ground heat exchanger during in-situ test". Renewable Energy 36, n. 5 (maggio 2011): 1578–87. http://dx.doi.org/10.1016/j.renene.2010.10.025.

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Cao, Xiaoling, Yanping Yuan, Liangliang Sun, Bo Lei, Nanyang Yu e Xiaojiao Yang. "Restoration performance of vertical ground heat exchanger with various intermittent ratios". Geothermics 54 (marzo 2015): 115–21. http://dx.doi.org/10.1016/j.geothermics.2014.12.005.

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Erol, Selçuk, e Bertrand François. "Multilayer analytical model for vertical ground heat exchanger with groundwater flow". Geothermics 71 (gennaio 2018): 294–305. http://dx.doi.org/10.1016/j.geothermics.2017.09.008.

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Moghanni, Reza, e Ali Hakkaki-Fard. "Optimizing vertical ground heat exchanger modelling through GPU-accelerated computation strategies". Renewable Energy 221 (febbraio 2024): 119790. http://dx.doi.org/10.1016/j.renene.2023.119790.

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GYOUTOKU, Toshiki, Koutaro TSUBAKI e Akio MIYARA. "414 Flow and heat transfer characteristics of heat transfer fluid in vertical ground heat exchanger". Proceedings of the Symposium on Environmental Engineering 2013.23 (2013): 312–13. http://dx.doi.org/10.1299/jsmeenv.2013.23.312.

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41

Michopoulos, A., T. Zachariadis e N. Kyriakis. "Operation characteristics and experience of a ground source heat pump system with a vertical ground heat exchanger". Energy 51 (marzo 2013): 349–57. http://dx.doi.org/10.1016/j.energy.2012.11.042.

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42

Tang, Ying Chun, Xiao Duo Ou e Bao Tian Wang. "Experimental Study on the Heat Transfer in Rock Layers with the Vertical Downhole Heat Exchanger". Advanced Materials Research 168-170 (dicembre 2010): 2243–48. http://dx.doi.org/10.4028/www.scientific.net/amr.168-170.2243.

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Through the in situ experiment of the ground-source heat pump (abbreviated as “GSHP”) system in Nanning Guangxi, this article has observed the temperature variation rules of the rock layers, by the temperature sensors buried in different depths and different locations from the Heat Exchanger. In addition, this article has also tried to explore the thermal environment of the rocks by analyzing the heat transfer of the soil layers acted under the thermal load in Southwest China regions where the ground water is abundant.

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Pater, Sebastian, e Włodzimierz Ciesielczyk. "Mathematical modelling of thermal and flow processes in vertical ground heat exchangers". Chemical and Process Engineering 38, n. 4 (1 dicembre 2017): 523–33. http://dx.doi.org/10.1515/cpe-2017-0041.

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Abstract The main task of mathematical modelling of thermal and flow processes in vertical ground heat exchanger (BHE-Borehole Heat Exchanger) is to determine the unit of borehole depth heat flux obtainable or transferred during the operation of the installation. This assignment is indirectly associated with finding the circulating fluid temperature flowing out from the U-tube at a given inlet temperature of fluid in respect to other operational parameters of the installation. The paper presents a model of thermal and flow processes in BHE consisting of two analytical models separately-handling processes occurring inside and outside of borehole. A quasi-three-dimensional model formulated by Zeng was used for modelling processes taking place inside the borehole and allowing to determine the temperature of the fluid in the U-tube along the axis of BHE. For modelling processes occurring outside the borehole a model that uses the theory of linear heat source was selected. The coupling parameters for the models are the temperature of the sealing material on the outer wall of the borehole and the average heat flow rate in BHE. Experimental verification of the proposed model was shown in relation to BHE cooperating with a heat pump in real conditions.

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Kim, Minsung, Gilbong Lee, Young-Jin Baik e Ho-Sang Ra. "Performance Evaluation of Geothermal Heat Pump With Direct Expansion Type Vertical Ground Heat Exchanger". Heat Transfer Engineering 36, n. 12 (21 gennaio 2015): 1046–52. http://dx.doi.org/10.1080/01457632.2015.981076.

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45

Salhein, Khaled, C. J. Kobus e Mohamed Zohdy. "Control of Heat Transfer in a Vertical Ground Heat Exchanger for a Geothermal Heat Pump System". Energies 15, n. 14 (21 luglio 2022): 5300. http://dx.doi.org/10.3390/en15145300.

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This paper presents a mathematical model of heat transfer behavior between the liquid inside vertical underground geothermal pipes and the surrounding ground for heating (in the winter) and cooling (in the summer) modes in a ground heat exchanger (GHE) that can optimize its output temperature. The GHE’s output temperature reaches the appropriate value when the water velocity is lowered enough. Subsequently, the proposed model was applied to a case study of a 400-ton geothermal heat pump system (GHPS) at Oakland University, in both the heating and cooling modes, to assess its validity and improve the GHE’s performance. The model was implemented in MATLAB using an ordinary differential equation (ODE) solver. Four different water velocities were used to demonstrate the significant effect of velocity on the loop exit temperature. Model predictive control (MPC) was designed to optimize the GHE’s output temperature by controlling the water velocity, which could reduce the energy consumption used for heat and water circulating pumps. The results reveal that the acceptable range of the water velocity for Oakland University’s GHE was between 0.35 and 0.45 m/s, which ensured that the heat pump system delivered the proper temperature to provide the Human Health Building (HHB) with a comfortable temperature regardless of the season. The suggested water velocity ranges in vertical single U-tube pipes with diameters of De 25 mm, De 32 mm, and De 40 mm are between 0.33 and 0.43 m/s, 0.35 to 0.45 m/s, and 0.38 to 0.48 m/s, respectively.

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Bi, Yuehong, Linger Chen e Chih Wu. "Measured performance of a solar-ground source heat pump system with vertical double spiral coil ground heat exchanger". International Journal of Ambient Energy 22, n. 1 (gennaio 2001): 3–11. http://dx.doi.org/10.1080/01430750.2001.9675381.

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47

Zhou, Hong, Jian Lv e Tailu Li. "Applicability of the pipe structure and flow velocity of vertical ground heat exchanger for ground source heat pump". Energy and Buildings 117 (aprile 2016): 109–19. http://dx.doi.org/10.1016/j.enbuild.2016.02.028.

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48

Mitchell, Matt S., e Jeffrey D. Spitler. "An Enhanced Vertical Ground Heat Exchanger Model for Whole-Building Energy Simulation". Energies 13, n. 16 (5 agosto 2020): 4058. http://dx.doi.org/10.3390/en13164058.

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This paper presents an enhanced vertical ground heat exchanger (GHE) model for whole-building energy simulation (WBES). WBES programs generally have computational constraints that affect the development and implementation of component simulation sub-models. WBES programs require models that execute quickly and efficiently due to how the programs are utilized by design engineers. WBES programs also require models to be formulated so their performance can be determined from boundary conditions set by upstream components and environmental conditions. The GHE model developed during this work utilizes an existing response factor model and extends its capabilities to accurately and robustly simulate at timesteps that are shorter than the GHE transit time. This was accomplished by developing a simplified dynamic borehole model and then exercising that model to generate exiting fluid temperature response factors. This approach blends numerical and analytical modeling methods. The existing response factor models are then extended to incorporate the exiting fluid temperature response factor to provide a better estimate of the GHE exiting fluid temperature at short simulation timesteps.

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Cui, Ping, Changliang Sun, Nairen Diao e Zhaohong Fang. "Simulation Modelling and Design Optimization of Vertical Ground Heat Exchanger-GEOSTAR Program". Procedia Engineering 121 (2015): 906–14. http://dx.doi.org/10.1016/j.proeng.2015.09.048.

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Chwieduk, Michal. "New global thermal numerical model of vertical U-tube ground heat exchanger". Renewable Energy 168 (maggio 2021): 343–52. http://dx.doi.org/10.1016/j.renene.2020.12.069.

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