scholarly journals Heat Transfer of Helix Energy Pile: Part 1: Traditional Cylinder Helix Energy Pile

2018 ◽  
Author(s):  
Guangqin Huang ◽  
Yajiao Liu ◽  
Xiaofeng Yang ◽  
Chunlong Zhuang
Keyword(s):  
Heat Transfer ◽  
Energy Pile

scholarly journals Improvement on the Calculation of Heat Transfer Rate for a New Type of Geothermal Energy Pile

IFCEE 2021 ◽  
2021 ◽  
Author(s):  
Yong Zou ◽  
Jie Huang ◽  
Fei Wang ◽  
John S. McCartney ◽  
Elahe Jafari
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Rate ◽  
Geothermal Energy ◽  
Transfer Rate ◽  
Energy Pile ◽  
New Type

Analytical Solution for Solid Cylindrical Heat Source Model With Convective Boundary Condition

2019 ◽  
Vol 141 (12) ◽  
Author(s):  
Yang Zhou ◽  
Cheng Xu ◽  
David Sego ◽  
Dong-hai Zhang
Keyword(s):  
Heat Transfer ◽  
Boundary Condition ◽  
Analytical Solution ◽  
Heat Source ◽  
Groundwater Flow ◽  
Convective Boundary Condition ◽  
Convective Boundary ◽  
Energy Pile ◽  
Special Cases ◽  
Scs Model

Abstract The energy pile technology has been widely used, and the solid cylindrical heat source (SCS) model is usually adopted to describe the heat transfer process between the energy pile and the surrounding soil. This paper investigates the SCS model with a convective boundary condition (SCS-3 model), and realistic conditions such as transversely isotropic ground and groundwater flow are all included in the model. An analytical solution for the problem is established using Green's function method and the theory of moving heat sources. Solutions for the SCS model with a boundary condition of the first kind (SCS-1 model) and for the line source (LS) model with a convective boundary condition (LS-3 model) are recovered as special cases of the solution in this paper. Computational examples are presented, and comparisons between different models are made. First, the SCS-1 model is compared with the SCS-3 model, showing the error caused by neglecting the surface convective effect. Second, the LS-3 model is compared with the SCS-3 model, showing the error associated with neglecting the size of heat source. The effects of groundwater flow velocity and convective heat transfer coefficient on the temporal and spatial variations of these errors are also investigated.

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 Simulation of the thermo-hydraulic response of energy piles in unsaturated soils

2020 ◽  
Vol 205 ◽  
pp. 05002
Author(s):  
Fatemah Behbehani ◽  
John S. McCartney
Keyword(s):  
Heat Transfer ◽  
Unsaturated Soils ◽  
Cumulative Effect ◽  
Degree Of Saturation ◽  
Soil Layers ◽  
Energy Pile ◽  
Axial Capacity ◽  
Coupled Heat Transfer ◽  
Heating And Cooling ◽  
Energy Piles

This paper focuses on the simulation of the coupled heat transfer and water flow in unsaturated soil layers surrounding a solitary energy pile undergoing heating and cooling cycles typical of a field-scale energy pile. The results indicate that heating leads to drying of the soil surrounding the energy pile, which has been shown in previous studies to result in an increase in axial capacity. During cooling, the degree of saturation was observed to recover to the value present before the start of heating initially, however, it will not recover in the following years. Which will lead to a cumulative effect after several cycles of heating and cooling. Heating and cooling cycles lead to an overall reduction in the thermal conductivity of the subsurface, reducing the heat transfer from the energy pile but also leading to greater storage of heat in the subsurface surrounding the pile.

scholarly journals Enhanced Heat Transfer Characteristics of Graphite Concrete and Its Application in Energy Piles

2018 ◽  
Vol 2018 ◽  
pp. 1-12 ◽  
Author(s):  
Qingwen Li ◽  
Lu Chen ◽  
Haotian Ma ◽  
Chung-Ho Huang
Keyword(s):  
Heat Transfer ◽  
High Heat ◽  
Transfer Efficiency ◽  
Heat Transfer Characteristics ◽  
Enhanced Heat Transfer ◽  
Energy Pile ◽  
Transfer Characteristics ◽  
Heat Transfer Efficiency ◽  
High Heat Transfer ◽  
Energy Piles

The latest research on energy piles demonstrates that most scholars are focusing their attention on optimization by designing more efficient heat exchanger coils, analyzing the heat pump matching parameters, and so on. However, after more than 20 years of development, these traditional methods for improving the heat transfer efficiency of energy piles have reached a bottleneck, and a new approach for the continued enhancement of this technology must be investigated. In this study, powdered graphite with high heat transfer characteristics was included in a concrete mix to create graphite concrete piles with enhanced heat transfer characteristics. The results from theoretical analysis, laboratory testing, and numerical simulation indicate that using graphite to improve the heat transfer efficiency of a concrete material is an effective method for enhancing the thermal efficiency of an energy pile system. The research results also show that the heat transfer coefficient of the concrete exhibits greater improvement when the graphite content is greater than 15% under the same environmental temperature. After studying the performance of the proposed graphite concrete energy pile under different environmental temperatures (10°C, 20°C, 30°C, and 40°C), the results indicate that the working efficiency of the energy pile is better in the summer than in the winter. Finally, parameters such as the cast-in pipe configuration and pile spacing are optimized.

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.

A novel 2-D equivalent numerical model of helix energy pile based on heat transfer characteristics of internal heat convection

Geothermics ◽  
2021 ◽  
Vol 95 ◽  
pp. 102150
Author(s):  
Ziming Liao ◽  
Guangqin Huang ◽  
Chunlong Zhuang ◽  
Hongyu Zhang ◽  
Shengbo Li ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Numerical Model ◽  
Internal Heat ◽  
Heat Convection ◽  
Heat Transfer Characteristics ◽  
Energy Pile ◽  
Transfer Characteristics
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