scholarly journals Thermal Effect on Structural Interaction between Energy Pile and Its Host Soil

2017 ◽  
Vol 2017 ◽  
pp. 1-9
Author(s):  
Qingwen Li ◽  
Lu Chen ◽  
Lan Qiao
Keyword(s):  
Thermal Stresses ◽  
Heat Transfer Process ◽  
Structural Element ◽  
Energy Pile ◽  
Structural Interaction ◽  
Comprehensive Method ◽  
Green Power ◽  
Energy Piles ◽  
Distribution Of Stress ◽  
Peak Value

Energy pile is one of the promising areas in the burgeoning green power technology; it is gradually gaining attention and will have wide applications in the future. Because of its specific structure, the energy pile has the functions of both a structural element and a heat exchanger. However, most researchers have been paying attention to only the heat transfer process and its efficiency. Very few studies have been done on the structural interaction between the energy pile and its host soil. As the behavior of the host soil is complicated and uncertain, thermal stresses appear with inhomogeneous distribution along the pile, and the peak value and distribution of stress will be affected by the thermal and physical properties and thermal conductivities of the structure and the host soil. In view of the above, it is important to determine thermal-mechanical coupled behavior under these conditions. In this study, a comprehensive method using theoretical derivations and numerical simulation was adopted to analyze the structural interaction between the energy pile and its host soil. The results of this study could provide technical guidance for the construction of energy piles.

Realistic Modeling of Edge Effect Stresses in Bimaterial Elements

1990 ◽  
Vol 112 (1) ◽  
pp. 16-23 ◽  
Author(s):  
J. W. Eischen ◽  
C. Chung ◽  
J. H. Kim
Keyword(s):  
Thermal Loading ◽  
Thermal Stresses ◽  
Theory Of Elasticity ◽  
Shear Stresses ◽  
Strength Of Materials ◽  
Approximate Methods ◽  
Interfacial Stresses ◽  
Distribution Of Stress ◽  
Laminated Structures ◽  
Peak Value

A classic paper by Timoshenko in 1925 dealt with thermal stresses in bimetal thermostats and has been widely used for designing laminated structures, and in contemporary studies of stresses in electronic devices. Timoshenko’s analysis, which is based on strength of materials theory, is unable to predict the distribution of the interfacial shear and normal stresses known to exist based on more sophisticated analyses involving the theory of elasticity (Bogy (1970) and Hess (1969)). Suhir (1986) has recently provided a very insightful approximate method whereby these interfacial stresses are estimated by simple closed-form formulas. The purpose of the present paper is to compare three independent methods of predicting the interfacial normal and shear stresses in bimaterial strips subjected to thermal loading. These are: 1.) Theory of elasticity via an eigenfunction expansion approach proposed by Hess, 2.) Extended strength of materials theory proposed by Suhir, 3.) Finite element stress analysis. Two material configurations which figure prominently in the electronics area have been studied. These are the molydeneum/aluminum and aluminum/silicon material systems. It has been discovered that when the two layers are nearly the same thickness, the approximate methods adequately predict the peak values of the interfacial stresses but err in a fundamental manner in the prediction of the distribution of stress. This may not be of concern to designers who are interested mainly in maximum stress alone. However, it has been shown that if one layer is relatively thin compared to the other, the approximate methods have difficulty in predicting both the peak value of stress and its associated distribution.

scholarly journals Analytical solution and process analysis of energy pile’s heat transfer rate

2020 ◽  
Vol 205 ◽  
pp. 05026
Author(s):  
Jun Yang ◽  
Zhenguo Yan ◽  
Zhengwei Zhang ◽  
Shu Zeng
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Rate ◽  
Transfer Rate ◽  
Heat Transfer Performance ◽  
Heat Transfer Process ◽  
Transfer Performance ◽  
Energy Pile ◽  
Energy Piles ◽  
The Difference ◽  
Surrounding Soil

With the ever-increasing energy demand and implications of climate change, the use of energy piles to absorb shallow geothermal energy to regulate room temperature of buildings is considered the best sustainable energy technology, especially in China, and the use of this technology is becoming increasingly popular. At present, studies generally uses the temperature field to analyze the heat transfer performance of the energy pile, which cannot represent the heat transfer rate distribution intuitively. In this study, we used mathematical models to provide an analytical solution to determine the heat transfer rate distribution between the energy pile and surrounding soil. Analysis of the heat transfer process of concrete piles in clay showed that the difference in thermal properties between the energy pile and the surrounding soil affected the whole heat transfer process, especially in the initial stage. The time required to reach the quasi-steady state mainly depended on the pile’s volume heat capacity, the thermal diffusivity of the pile and the surrounding soil. In engineering practice, to enhance the heat transfer performance of energy piles, the following measures can be taken: reduce the difference in thermal properties between the energy pile and surrounding soil and increase the distance between energy piles to improve the heat transfer conditions.

scholarly journals Effect of nearby piles and soil properties on the thermal behaviour of a field-scale energy pile

2020 ◽  
Author(s):  
Aria Moradshahi ◽  
Mohammed Faizal ◽  
Abdelmalek Bouazza ◽  
John S. McCartney
Keyword(s):  
Thermal Conductivity ◽  
Thermal Expansion ◽  
Elastic Modulus ◽  
Soil Properties ◽  
Thermal Expansion Coefficient ◽  
Thermal Stresses ◽  
Thermal Response ◽  
Soil Thermal Conductivity ◽  
Energy Pile ◽  
Energy Piles

The thermal response of an energy pile that is part of a pair of energy piles spaced at 3.5 m, was examined experimentally and numerically. The field tests included: (1) heating of the energy pile alone; (2) heating of both energy piles simultaneously, and (3) heating of the other energy pile while the considered energy pile was not heated. Parametric studies of the validated numerical model was performed to understand the effects of varying soil thermal conductivity, thermal expansion coefficient, and elastic modulus on the thermal response of the considered energy pile. The numerical results confirmed the field results that radial thermal stresses were insignificant compared to axial thermal stresses. The impact of the soil elastic modulus was more significant on the thermal stresses of the energy pile compared to the effects of soil thermal conductivity and thermal expansion coefficient. The thermal stresses of the considered energy pile were not significantly affected when both energy piles were heated simultaneously, even though ground temperature changes between the energy piles were more significant due to thermal interaction. Only minor thermal effects on the non-thermal pile were observed during heating of one of the energy piles for different soil properties.

Numerical Study on the Effect of Inner Tube Position on Heat Transfer Process in Self-Recuperative Radiant Tube

2011 ◽  
Vol 228-229 ◽  
pp. 676-680 ◽  
Author(s):  
Ye Tian ◽  
Xun Liang Liu ◽  
Zhi Wen
Keyword(s):  
Heat Transfer ◽  
Transfer Process ◽  
Numerical Study ◽  
Flame Temperature ◽  
Three Dimensional ◽  
Mathematic Model ◽  
Heat Transfer Process ◽  
Bulk Temperature ◽  
Radiant Tube ◽  
Peak Value

A three-dimensional mathematic model is developed for a 100kw single-end recuperative radiant tube and the simulation is performed with the CFD software FLUENT. Also it is used to investigate the effect of distance between combustion chamber exit and inner tube on heat transfer process. The results suggest that the peak value of combustion flame temperature drops along with the increasing of distance, which leads to low NOX discharging. Also radiant tube surface bulk temperature decreases, which causes radiant tube heating performance losses.

Laboratory-scale pull-out tests on a geothermal energy pile in dry sand subjected to heating cycles

2020 ◽  
Vol 57 (11) ◽  
pp. 1754-1766
Author(s):  
Rehab Elzeiny ◽  
Muhannad T. Suleiman ◽  
Suguang Xiao ◽  
Mu’ath Abu Qamar ◽  
Mohammed Al-Khawaja
Keyword(s):  
Load Transfer ◽  
Pressure Sensors ◽  
Temperature Sensors ◽  
Heat Pumps ◽  
Laboratory Model ◽  
Ground Source Heat Pumps ◽  
Energy Pile ◽  
Pull Out ◽  
Energy Piles ◽  
Dry Sand

Ground source heat pumps coupled with energy piles operate intermittently, subjecting the piles to temperature cycles throughout their lifetime. The research presented in this paper focuses on studying the thermomechanical behavior of energy piles subjected to heating cycles. Laboratory model tests were performed at the soil-structure interaction (SSI) facility at Lehigh University. A fully instrumented model energy pile, embedded in dry sand, was subjected to different number of heating cycles followed by axial pull-out loading. Baseline (room temperature), five heating cycles (5HC), and 100 heating cycles (100HC) tests are reported in this paper. The soil was instrumented with temperature sensors and pressure sensors, while the pile was instrumented with temperature sensors, strain gauges, and pressure sensors. The test results showed that the peak pull-out loads for the baseline, 5HC, and 100HC were 2794 N, 3633 N (30% higher than baseline), and 3559 N (27% higher than baseline), respectively. It was also found that subjecting the pile to large number of daily heating cycles induced small degradation in the load transfer or the peak pull-out load in dry sand.

Thermomechanical Behavior of Energy Piles and Interactions within Energy Pile–Raft Foundations

2020 ◽  
Vol 146 (9) ◽  
pp. 04020079
Author(s):  
Jincheng Fang ◽  
Gangqiang Kong ◽  
Yongdong Meng ◽  
Lehua Wang ◽  
Qing Yang
Keyword(s):  
Thermomechanical Behavior ◽  
Energy Pile ◽  
Energy Piles ◽  
Raft Foundations

Flapping-Wing Fluid–Structural Interaction Analysis Using Corotational Triangular Planar Structural Element

AIAA Journal ◽  
2016 ◽  
Vol 54 (8) ◽  
pp. 2265-2276 ◽  
Author(s):  
Haeseong Cho ◽  
JunYoung Kwak ◽  
SangJoon Shin ◽  
Namhun Lee ◽  
Seungsoo Lee
Keyword(s):  
Interaction Analysis ◽  
Flapping Wing ◽  
Structural Element ◽  
Structural Interaction

scholarly journals Thermo-mechanical performance of a proposed energy pile system in cold regions

2020 ◽  
Author(s):  
Maryam Saaly ◽  
Pooneh Maghoul ◽  
Hartmut Hollaender ◽  
Ali Fatolahzadeh
Keyword(s):  
Urban Areas ◽  
Mechanical Response ◽  
Axial Stress ◽  
Cold Climate ◽  
Thermal Loads ◽  
Foundation Soil ◽  
Cold Regions ◽  
Energy Pile ◽  
Energy Piles ◽  
Thermal Imbalance

Energy piles are bi-functional structural elements that are used to support the structural loads of a building and to operate as a geo-heat exchanger for shallow geothermal energy systems. In urban areas, energy piles can eventually be used to harvest the heat loss through the basement enclosure and re-inject the energy to the building for the heating and cooling purposes. In spite of a higher thermal profile beneath the buildings due to energy loss through the below-grade envelope, an underground thermal imbalance may still occur due to the application of energy piles in cold regions. This paper aims to study the structural performance of an energy pile in cold regions considering the potential occurrence of thermal imbalance in the foundation soil through a Thermo-Mechanical (TM) analysis. This will be the first step of adoption of such a technology in Canadian cold climate. Results showed a safe margin between the pile settlement and the allowable settlement. However, the axial stress applied to the pile increased by 9% due to thermal loads. In addition, a maximum decrease of 9% in mobilized shaft friction along the pile-soil interface was recorded due to the thermal loads. To consider the energy piles as an alternative for buildings energy supply in cold regions, further considerations should be made to keep the mechanical response of the energy piles in the admissible range.

scholarly journals Energy-Pile Model Verification

2020 ◽  
Author(s):  
Ondřej Šikula ◽  
◽  
Richard Slávik ◽  
Jan Eliáš ◽  
Jakub Oravec ◽  
...  
Keyword(s):  
Heat Conduction ◽  
Low Cost ◽  
Energy Performance ◽  
Model Verification ◽  
Transient Phenomenon ◽  
Conduction Model ◽  
Energy Pile ◽  
Heating And Cooling ◽  
Energy Piles ◽  
Pile Model

Equipping the foundation piles with a liquid circuit pipeline makes it possible to use the advantageous ther-mal capacity of the soil for heating and cooling buildings at low cost. The energy performance of the energy-pile in a soil is a transient phenomenon dependent on many parameters, which could be investigate by a computational model. The contribution deals with the description and verification of a new numerical computational software based on a simplified 2D and 2D rotational symmetrical heat conduction model being developed for energy-piles modeling.

scholarly journals The mechanisms underlying long-term shaft resistance enhancement of energy pile in clays

2020 ◽  
Author(s):  
Saeed Yazdani ◽  
Sam Helwany ◽  
Guney Olgun
Keyword(s):  
Normal Load ◽  
Comprehensive Analysis ◽  
Normal Stresses ◽  
Lateral Stress ◽  
Energy Pile ◽  
Shaft Resistance ◽  
Energy Piles ◽  
Constant Normal Stiffness ◽  
Constant Normal Load

Although there are several studies indicating that heating increases the long-term shaft resistance of energy piles, the mechanisms by which heating causes this increase have not been adequately evaluated yet. This article aims to perform comprehensive analysis and discussion to assess the important factors contributing to this increase by integrating the findings from three recently published papers studying the thermo-mechanical behavior of clay and clay-pile interface. In these three studies, reconstituted kaolin clay was used, and cyclic and monotonic heat ranging between 24° C and 34°C were applied to the clay and interface. The interface was sheared under two stiffness boundary conditions; Constant Normal Stiffness (CNS) and Constant Normal Load (CNL), where the normal stresses varied between 100 kPa and 300 kPa. The analysis performed in this article reveals that the increase in strength of interface under CNL condition is primarily attributed to clay stiffening at interface. However, the increase in shaft resistance under CNS condition is primarily attributed to the heating-induced increase of effective lateral stress, although clay stiffening at interface also partially contributes to the total increase of shaft resistance.

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