A Comprehensive Review of Backfill Materials and Their Effects on Ground Heat Exchanger Performance

Geothermal energy systems can help in achieving an environmentally friendly and more efficient energy utilization, as well as enhanced power generation and building heating/cooling, thereby making energy systems more sustainable. The role of the backfill material, which fills the space between a pipe and the surrounding soil, is important in the operation of ground heat exchangers. Among the review articles on parameters affecting ground heat exchanger performance published over the past eight years, only two discuss types of backfill materials, even though the importance of these materials is significant. However, no review has yet been published exclusively on the kinds of backfill materials used in ground heat exchangers. This article addresses this need by providing a comprehensive review of a variety of types of backfill materials and their effects on ground heat exchanger performance. For organizational purposes, the backfill materials are divided into two categories: conventional backfill materials (pure and mixed materials) and modern backfill materials (improved phase change materials). Both categories are described in detail. It is shown that bentonite has been used considerably as a conventional backfill material in ground heat exchangers, followed by silica sand and coarse/fine sand. Moreover, acid and shape-stabilized phase change materials have been applied mostly as modern backfill materials in ground heat exchangers. It is observed, generally, that conventional backfill materials are used more than modern backfill materials in ground heat exchangers. It should be noted that the data covered in this study are not from all the articles published in the last eight years, but rather from a subset based on specific criteria (i.e., English-language papers published in reputable journals). These articles were published by authors from numerous countries. The results may, as a consequence, have some corresponding limitations, but these are likely to be minor.

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Evaluation and Improvement of Thermal Energy of Heat Exchangers with SWCNT, GQD Nanoparticles and PCM (RT82)

Journal of Advanced Research in Fluid Mechanics and Thermal Sciences ◽

10.37934/arfmts.79.1.153168 ◽

2020 ◽

Vol 79 (1) ◽

pp. 153-168

Author(s):

Mohammadreza Hasandust Rostami ◽

Gholamhassan Najafi ◽

Ali Motevalli ◽

Nor Azwadi Che Sidik ◽

Muhammad Arif Harun

Keyword(s):

Energy Storage ◽

Heat Exchanger ◽

Heat Exchange ◽

Phase Change ◽

Thermal Energy ◽

Thermal Efficiency ◽

Heat Exchangers ◽

Phase Change Materials ◽

Single Wall Carbon Nanotubes ◽

In Series

Today, due to the reduction of energy resources in the world and its pollutants, energy storage methods and increase the thermal efficiency of various systems are very important. In this research, the thermal efficiency and energy storage of two heat exchangers have been investigated in series using phase change materials (RT82) and single wall carbon nanotubes (SWCNT) and graphene quantum dot nanoparticles (GQD) In this research, two heat exchangers have been used in combination. The first heat exchanger was in charge of storing thermal energy and the second heat exchanger was in charge of heat exchange. The reason for this is to improve the heat exchange of the main exchanger (shell and tube) by using heat storage in the secondary exchanger, which has not been addressed in previous research. The results of this study showed that using two heat exchangers in series, the thermal efficiency of the system has increased. Also, the heat energy storage of the double tube heat exchanger was obtained using phase change materials in the single-walled carbon nanotube composition of about 3000 W. The average thermal efficiency of the two heat exchangers as the series has increased by 52%. In general, the effect of the two heat exchangers on each other was investigated in series with two approaches (energy storage and energy conversion) using fin and nanoparticles, which obtained convincing results.

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Analysis of Yearly Effectiveness of a Diaphragm Ground Heat Exchanger Supported by an Ultraviolet Sterilamp

Energies ◽

10.3390/en13112804 ◽

2020 ◽

Vol 13 (11) ◽

pp. 2804

Author(s):

Sławomir Rabczak ◽

Paweł Kut

Keyword(s):

Heat Exchanger ◽

Ultraviolet Radiation ◽

Heat Exchangers ◽

Ground Heat Exchanger ◽

Atmospheric Air ◽

Ground Heat Exchangers ◽

Air Handling Unit ◽

Operational Costs ◽

Uv C

Ground heat exchangers supplement ventilation systems and provide notable power gains by heating ventilated air during winter and cooling it in summer. Additionally, they prevent recuperator exchangers from freezing. In atmospheric air, there are many types of contaminants and microorganisms that significantly affect the quality of ventilated air. The air that flows through the system of pipes of the heat exchanger may also become contaminated. In order to remove contamination from ventilated air, ultraviolet radiation may be used. This article presents a concept of using a UV-C (ultraviolet with a wavelength of 200–280 nm) lamp in the air duct in front of the air handling unit connected to the ground heat exchanger. The UV-C lamp, apart from clearing the air, may also decrease operational costs thanks to eliminating contamination that forms bacterial jelly on heat exchanger elements.

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Determination of Optimum Design Parameters of Horizontal Parallel Pipe and Vertical U-Tube Ground Heat Exchangers

Volume 1: Heat Transfer in Energy Systems; Thermophysical Properties; Heat Transfer Equipment; Heat Transfer in Electronic Equipment ◽

10.1115/ht2009-88206 ◽

2009 ◽

Author(s):

Hakan Demir ◽

Ahmet Koyun ◽

S¸. O¨zgu¨r Atayılmaz

Keyword(s):

Thermal Conductivity ◽

Energy Consumption ◽

Heat Exchanger ◽

Objective Function ◽

Heat Exchangers ◽

Ground Heat Exchanger ◽

Ground Source Heat Pump ◽

Soil Thermal Conductivity ◽

Ground Heat Exchangers ◽

Ground Source

The most important part of a ground source heat pump (GSHP) is the ground heat exchanger (GHE) that consists of pipes buried in the soil and is used for transferring heat between the soil and the heat exchanger of the ground source heat pump. Soil composition, thermal properties and water content affect the length of ground heat exchanger. Another parameter affects the size of the ground heat exchanger is the shape. There are two basic ground heat exchanger configurations: vertical U-tube and horizontal parallel pipe. There are plenty of works on ground source heat pumps and ground heat exchangers in the literature. Most of the works on ground heat exchangers are based on the heat transfer in the soil and temperature distribution around the coil. Some of the works for thermo-economic optimization of thermal systems are based on thermodynamic cycles. This study covers comparative thermo-economical analysis of horizontal parallel pipe and vertical u-tube ground heat exchangers. An objective function has been defined based on heating capacity, investment and energy consumption costs of ground heat exchanger. Investment and energy consumption costs were taken into account as total cost in the objective function. The effects of the soil thermal conductivity, number of pipes, thermal capacity of ground heat exchanger, pipe diameter and the burial depth on the objective function were examined. The main disadvantage of U-tube ground heat exchanger is higher borehole cost that makes installation cost higher than parallel pipe ground heat exchanger. To make reference functions equal for both type of ground heat exchangers, the borehole cost must be under 20 $/m (now 55 $/m) for a given heating or cooling capacity. The performance of ground heat exchangers depends on the soil characteristics especially the soil thermal conductivity.

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Research on the Initial Operating Performance of Ground Heat Exchangers

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.448-453.2897 ◽

2013 ◽

Vol 448-453 ◽

pp. 2897-2902

Author(s):

Xue Ting Huang ◽

Yan Ling Guan ◽

Chao Jiang

Keyword(s):

Heat Exchanger ◽

Heat Exchangers ◽

Heat Transfer Performance ◽

Cfd Simulation ◽

Operating Performance ◽

Operating Time ◽

Three Dimensional ◽

Ground Heat Exchanger ◽

Initial Operation ◽

Ground Heat Exchangers

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.

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The Analysis on the Effect of the Loading Capacity of the Pile with Buried Tubes

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.243-249.2889 ◽

2011 ◽

Vol 243-249 ◽

pp. 2889-2892

Author(s):

Wen Wang ◽

Rui Han ◽

Man Xia Wu ◽

Chun Mei Zheng

Keyword(s):

Heat Exchanger ◽

Heat Exchangers ◽

Engineering Practice ◽

Loading Capacity ◽

Tube Model ◽

Ground Heat Exchanger ◽

Engineering Applications ◽

Spiral Tube ◽

Energy Pile ◽

Ground Heat Exchangers

The pile ground heat exchanger is devised to overcome the shortcomings in configuration of existing ground heat exchangers. In view of its engineering applications of the spiral tubes ground heat exchanger inside foundation piles, the effects of them on the loading capacity features of the pile are studied. Firstly, a spiral tube model is proposed for the energy pile system and the model is proved correctly compared with engineering practice of the piles.Then，in the FEM software the model is applied in the comparasion between the piles with and without buried tubes .As a result, the effects of buried tubes on the loading capacity features of the piles are found.

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Geothermal Energy Use for the Additional Heat Supply of a Residential Building

Slovak Journal of Civil Engineering ◽

10.2478/sjce-2020-0026 ◽

2020 ◽

Vol 28 (4) ◽

pp. 15-22

Author(s):

Oleksandra Kuzmenko ◽

Kostiantyn Dikarev ◽

Daniil Rodionov ◽

Oleksandra Martysh ◽

Anar Iskenderov ◽

...

Keyword(s):

Heat Exchanger ◽

Heat Exchangers ◽

Heat Recovery ◽

Energy Use ◽

Residential Building ◽

Ground Heat Exchanger ◽

Ground Heat Exchangers ◽

Recovery System ◽

Heat Recovery System ◽

Building Ventilation

AbstractTo ensure low-energy consumption in new generation energy-efficient houses, the technology of a ground heat exchanger with a heat recovery system is used almost everywhere. However, this technology has not been widely disseminated in Ukraine. The work is aimed at presenting insights from research on the combination of ground heat exchangers with a heat recovery system for building ventilation by analyzing the operational and techno-economic indicators obtained. Current studies permit revealing the optimal configuration of a ground heat exchanger with a heat recovery system for ventilation in a residential building in order to analyze the efficiency of ground heat exchangers with a heat recovery system for ventilation of a residential building in comparison with several conventional ventilation options to assess the main price/ performance ration of the process of constructing a ground heat exchanger with a heat recovery system and to determine the duration of the technological process, the labor-intensive characteristics, and the estimated cost of the technology.

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Soil Profile and Ground Properties Influence on Vertical Ground Heat Exchanger Efficiency

Proccedings of 10th International Conference "Environmental Engineering" ◽

10.3846/enviro.2017.253 ◽

2017 ◽

Cited By ~ 1

Author(s):

Michał Chwieduk ◽

Artur Rusowicz ◽

Hanna Jędzrzejuk

Keyword(s):

Heat Exchanger ◽

Soil Profile ◽

Heat Exchangers ◽

Heat Pumps ◽

Symmetric Model ◽

Ground Heat Exchanger ◽

Ground Heat Exchangers ◽

Calculation Results ◽

Vertical Ground ◽

The Impact

Soil properties have a significant impact on the performance of ground heat exchangers. Exchangers cooperating with heat pumps are a reliable and efficient source of renewable energy. In the article concentric vertical ground heat exchanger is analysed, which is a common application cooperating with heat pumps. Soil and ground properties have great im-portance during sizing the system, i.e.: determining the length, configuration and deployment of ground heat exchangers. With the depth the soil/ground type and its properties can change significantly. In addition, occurrence of a ground water can influence physical and thermal properties. Determination of soil type present at different depths in a specific location is possible by performing a soil profile. The article presents an analysis of the impact of two soil profiles on the efficien-cy of the vertical ground heat exchanger. The analysis was performed based on the model of a single heat exchanger made using CFD (Computational Fluid Dynamics) program. The model is divided into two parts: model of heat ex-changer together with grout filling the borehole, second: axis-symmetric model of the ground surrounding the exchanger. Both models are coupled by first-type boundary condition. Simulations of ground heat exchanger work are made for a part of heating season period. The calculation results were compared to reference one with uniform ground profiles. Dif-ference in heat rejected form ground in two analysed does not show high influence of ground layers on ground heat ex-changer performance. On the other hand, results strongly depends on analysed soil profile.

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