基于能量桩现场试验的土体综合热导率系数研究

Study of soil comprehensive thermal conductivity coefficient based on field test of energy pile

能量桩技术兼具支撑上部荷载和浅层地热能换热器双重功能;作为一种节能减排技术,近年来在国内外获得了一定的发展。然而,目前简单套用基于传统地埋管换热器获得的土体综合热导率系数,无法准确计算能量桩换热效率。依托河南理工大学某低承台3×3能量桩群桩工程应用,开展基于能量桩的土体综合热导率系数测试现场试验和数值模拟研究,分析加热时长、加热功率、流速及桩长等因素对土体综合热导率系数的影响规律,继而探讨能量桩在群桩中的布置形式对土体综合热导率系数的影响规律。研究结果表明,基于传统地源热泵测试所发展起来的土体综合热导率系数线热源分析方法,并不适用于分析基于能量桩现场实测所获得的相关数据;有必要推导一套考虑桩径影响的、适用于能量桩的土体综合热导率系数测试与计算分析方法。

Energy pile is an energy-saving and emission-reduction technology, combining the functions of structure load supporter and shallow geothermal heat exchanger. There has been application in the world in recent years. Normally, the comprehensive thermal conductivity coefficient of soil is measured through ground source heat pump technique. However, this value is unsuitable to calculate the heat exchange efficiency of energy pile accurately. Field tests and numerical simulations on the soil thermal conductivity coefficient were obtained in energy pile group with low cap located on Henan Polytechnic University. The influence of heating time, heating power, flow rate, pile length and the arrangement of energy pile in groups on the soil comprehensive thermal conductivity coefficient are analyzed. It shows that the line heat source analysis method, based on the ground source heat pump testing, is unsuitable for the calculation of soil comprehensive thermal conductivity coefficient. Hence, it is necessary to develop one testing and analyzing method which can considering pile diameter, etc.