scholarly journals Field test on thermal response characteristics of an energy pile in underground row piles

2020 ◽  
Vol 205 ◽  
pp. 05011
Author(s):  
Gangqiang Kong ◽  
Yang Zhou ◽  
Di Wu ◽  
Gaoxiang Yin ◽  
Hefu Pu
Keyword(s):  
Thermal Response ◽  
Field Tests ◽  
Mechanical Analysis ◽  
Input Power ◽  
Underground Structures ◽  
Energy Pile ◽  
Response Characteristics ◽  
Energy Piles ◽  
Shallow Geothermal Energy ◽  
Temperature Strain

Underground row piles are usually used in excavation of underground structures and abandoned after structural construction. The heat exchanger tubes embedded in the underground row piles can be severed as energy piles, which can exchange shallow geothermal energy. The construction process of the energy pile in the underground row piles was introduced. Compared with the traditional single energy pile, there is a special characteristic of the energy pile in underground row piles: piles are linked as a whole by the top beam at the top of the row pile. Field tests on the thermal response and thermo-mechanical characteristics of the energy pile in underground row piles were performed. The stable input power of 2.07 kW. The distribution of temperature, strain, and stress of pile body along depth were measured and discussed. It shows that the measured comprehensive thermal conductivity coefficient of soil is 3.72W/(m×K). In the thermo-mechanical analysis after heating, due to the end restrains by the top beam and toe in stiff rock, the rate of thermal stress to temperature change at the top and toe are -0.101 MPa/℃ (34% of fully restrain) and -0.061 MPa/℃ (20% of fully restrain).

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.

scholarly journals Thermo-Mechanical Performance of a Phase Change Energy Pile in Saturated Sand

Symmetry ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 1781
Author(s):  
Ting Du ◽  
Yubo Li ◽  
Xiaohua Bao ◽  
Waiching Tang ◽  
Hongzhi Cui
Keyword(s):  
Heat Transfer ◽  
Numerical Model ◽  
Phase Change ◽  
Thermal Loading ◽  
Plastic Material ◽  
Thermal Response ◽  
Thermal Loads ◽  
Saturated Sand ◽  
Energy Pile ◽  
Energy Piles

To reduce the thermal response and improve the heat storage capacity of energy piles, a phase change (PC) energy pile was proposed. This innovative PC pile is made of concrete containing macro-encapsulated PCM hollow steel balls (HSB) as coarse aggregates. A numerical model was developed to simulate the thermo-mechanical behaviors of the PC pile under thermal cycles and sustained loading. The computational model is a three-dimensional model that is symmetrical for the two horizontal directions in geometry. Heat transfer process follows conservation laws of energy. The numerical model was validated by the experiments conducted on the PC pile and the results show that the model can reproduce the major thermo-mechanical effects. Then, the model was used to compare the performance between the ordinary concrete pile and the PC pile in saturated sand under the same experimental conditions, where the piles were considered to be thermo-elastic in nature and the sand was considered as a Mohr–Coulomb elastic-plastic material. The thermo-mechanical response of the PC pile under different thermal loads was analyzed. The results show that at the end of heating, the temperature, strain, and displacement of the PC pile were lower than those of the ordinary pile. As the thermal loading increased, the range of temperature change in the soil around the PC pile increased, as well as the strain and displacement of the pile. The residual strain and plastic displacement after the temperature cycles also increased with the increase of thermal loading. Therefore, when designing phase change energy piles, full consideration should be given to the matching of thermal loads and PC temperature, so as to balance the heat transfer rate of the pile and the thermal response.

scholarly journals Field Test and Numerical Simulation on the Long-Term Thermal Response of PHC Energy Pile in Layered Foundation

Sensors ◽  
2021 ◽  
Vol 21 (11) ◽  
pp. 3873
Author(s):  
Guozhu Zhang ◽  
Ziming Cao ◽  
Yiping Liu ◽  
Jiawei Chen
Keyword(s):  
Thermal Conductivity ◽  
Heat Exchange ◽  
Temperature Variation ◽  
Thermal Response ◽  
Ground Temperature ◽  
Short Term ◽  
Energy Pile ◽  
Backfill Soil ◽  
Short And Long Term

Investigation on the long-term thermal response of precast high-strength concrete (PHC) energy pile is relatively rare. This paper combines field experiments and numerical simulations to investigate the long-term thermal properties of a PHC energy pile in a layered foundation. The major findings obtained from the experimental and numerical studies are as follows: First, the thermophysical ground properties gradually produce an influence on the long-term temperature variation. For the soil layers with relatively higher thermal conductivity, the ground temperature near to the energy pile presents a slowly increasing trend, and the ground temperature response at a longer distance from the center of the PHC pile appears to be delayed. Second, the short- and long-term thermal performance of the PHC energy pile can be enhanced by increasing the thermal conductivity of backfill soil. When the thermal conductivities of backfill soil in the PHC pile increase from 1 to 4 W/(m K), the heat exchange amounts of energy pile can be enhanced by approximately 30%, 79%, 105%, and 122% at 1 day and 20%, 47%, 59%, and 66% at 90 days compared with the backfill water used in the site. However, the influence of specific heat capacity of the backfill soil in the PHC pile on the short-term or long-term thermal response can be ignored. Furthermore, the variation of the initial ground temperature is also an important factor to affect the short-and-long-term heat transfer capacity and ground temperature variation. Finally, the thermal conductivity of the ground has a significant effect on the long-term thermal response compared with the short-term condition, and the heat exchange rates rise by about 5% and 9% at 1 day and 21% and 37% at 90 days as the thermal conductivities of the ground increase by 0.5 and 1 W/(m K), respectively.

Experimental Investigation and Analysis on Dynamic Strain of Leading Trailing Shoe Drum Brake

2017 ◽  
Author(s):  
Xiaoying Wang ◽  
Zijie Fan ◽  
Jia Li ◽  
LiangJin Gui
Keyword(s):  
Optimization Design ◽  
Test Procedure ◽  
Mechanical Analysis ◽  
Dynamic Strain ◽  
Wireless Data ◽  
Drum Brake ◽  
Wireless Data Acquisition ◽  
Drum Brakes ◽  
Temperature Strain ◽  
Temperature Time

The research on the dynamic strain of drum brakes is of great significance in performance evaluation, structure optimization and fatigue prediction. Based on current research of strain experiments and measuring technology, a new test procedure is proposed to investigate strain and temperature information of a working drum. Wireless data acquisition system and high-temperature strain gauges are applied. The strain-time and temperature-time curves are studied on the conditions of emergency brake and continuous brake. A tribological and thermo-mechanical analysis are conducted by using software ABAQUS. Results show that the strain is uneven when the drum contacts different zones of friction plates. Seasonal variation is another feature and a set of four wave crests repeats during the rotation. Meanwhile, thermal effect is proved important to strain. The simulation results coincide well with experiments, proving that this method provides a practical way to verify the calculation. The study also lays the foundation for the following fatigue analysis and optimization design.

scholarly journals Investigations of dynamic characteristics of a tall industrial chimney due to light wind and solar radiation

2013 ◽  
Vol 12 (2) ◽  
pp. 087-094 ◽  
Author(s):  
Peter Breuer ◽  
Tadeusz Chmielewski ◽  
Piotr Górski ◽  
Eduard Konopka ◽  
Lesław Tarczyński
Keyword(s):  
Solar Radiation ◽  
Dynamic Characteristics ◽  
Field Tests ◽  
Power Station ◽  
Temperature Variations ◽  
Response Characteristics ◽  
Modal Damping ◽  
Wind Response ◽  
Satellite Signal ◽  
Air Temperature Variations

The present paper describes field tests conducted on the 300 m tall industrial chimney, located in the power station of Bełchatów (Poland), where the GPS rover receivers were installed at three various levels. The objectives of these GPS tests were to investigate the deformed vertical profile of this chimney, and its dynamic characteristics, i.e. the first natural frequency and the modal damping ratios. The results for the satellite signal receptions, the synopsis of recorded baselines and their ambiguity solutions, drifts of the chimney due to solar radiation and air temperature variations and dynamic wind response characteristics are presented.

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.

A composite cylindrical model and its application in analysis of thermal response and performance for energy pile

2014 ◽  
Vol 84 ◽  
pp. 324-332 ◽  
Author(s):  
Pingfang Hu ◽  
Jing Zha ◽  
Fei Lei ◽  
Na Zhu ◽  
Tianhua Wu
Keyword(s):  
Thermal Response ◽  
Energy Pile ◽  
Cylindrical Model ◽  
And Performance

Analysis of Hybrid Electric/Thermofluidic Control for Wet Shape Memory Alloy Actuators

2009 ◽  
Author(s):  
Leslie Flemming ◽  
Stephen Mascaro
Keyword(s):  
Control Strategies ◽  
Fluid Dynamic ◽  
Thermal Response ◽  
Electric Heating ◽  
Electrical Heating ◽  
Linear Contraction ◽  
Heating And Cooling ◽  
The Wire ◽  
Temperature Strain ◽  
Strain Model

A wet SMA actuator is characterized by an SMA wire embedded within a compliant fluid-filled tube. Heating and cooling of the SMA wire produce a linear contraction and extension of the wire. Thermal energy can be transferred to and from the wire using combinations of resistive heating and free/forced convection using hot and cold fluid. The goal of this paper is to analyze the speed and efficiency of wet SMA actuators using a variety of control strategies involving different combinations of electrical and thermofluidic inputs. A computational fluid dynamic model is used in conjunction with a temperature-strain model to simulate the thermal response of the wire and compute strains, contraction/extension times and efficiency. The simulations produce cycling rates of up to 5 Hz for electrical heating and fluidic cooling, and up to 2 Hz for fluidic heating and cooling. The results demonstrate efficiencies up to 0.5% for electric heating and up to 0.2% for fluidic heating.

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