Influences on the thermal efficiency of energy piles
Influences on the thermal efficiency of energy piles
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DOI：
10.1016/j.energy.2015.02.001
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发表时间：
2015-03-15
期刊：
影响因子：
9
通讯作者：
Loveridge, Fleur A.
中科院分区：
文献类型：
--
作者：
Cecinato, Francesco;Loveridge, Fleur A.
能源桩最近已经成为一种可行的替代埋管换热器，但其能源效率迄今为止几乎没有看到研究。在这项工作中，有限元数值模型的准确的三维分析瞬态扩散和对流热交换现象发生在地热结构。该模型是通过再现的测试桩上进行的热响应测试的结果，和线性热源解析解的平均响应进行验证。然后，该模型进行了参数分析，以确定在最大限度地提高桩能源效率的关键因素。结果表明，最有影响的设计参数是管道的数量，可以更方便地增加，在合理的范围内，相比，增加桩的尺寸。改变桩长，混凝土导电性，桩直径和混凝土保护层的影响也进行了讨论，根据其能量的含义。与工程直觉相反，只要足以确保湍流，流体流量在能源效率中并不那么重要。本文提出的模型可以很容易地适用于其他类型的地热结构的详细研究。(C)2015爱思唯尔有限公司版权所有。
Energy piles have recently emerged as a viable alternative to borehole heat exchangers, but their energy efficiency has so far seen little research. In this work, a finite element numerical model is developed for the accurate 3D analysis of transient diffusive and convective heat exchange phenomena taking place in geothermal structures. The model is validated by reproducing both the outcome of a thermal response test carried out on a test pile, and the average response of the linear heat source analytical solution. Then, the model is employed to carry out a parametric analysis to identify the key factors in maximising the pile energy efficiency. It is shown that the most influential design parameter is the number of pipes, which can be more conveniently increased, within a reasonable range, compared to increasing the pile dimensions. The influence of changing pile length, concrete conductivity, pile diameter and concrete cover are also discussed in light of their energetic implications. Counter to engineering intuition, the fluid flowrate does not emerge as important in energy efficiency, provided it is sufficient to ensure turbulent flow. The model presented in this paper can be easily adapted to the detailed study of other types of geothermal structures. (C) 2015 Elsevier Ltd. All rights reserved.