地埋管地源热泵水泥基回填材料导热系数预测模型

Prediction model of thermal conductivity of cement-based grouts for ground source heat pump

针对水泥基材料导热系数模型的研究较少的现状,为了给水泥基材料的开发与研究提供一种可应用的导热系数计算方法,根据水泥基材料的成分组成和物理结构,应用傅里叶导热定律,建立了固-液-气三相导热系数预测模型。并基于地埋管地源热泵水泥基回填材料进行了参数识别,得到了适用于水泥基回填材料的参数取值方法和取值组合。该模型可以预测骨料含量(砂灰比)、水灰比(孔隙率)、饱和度、单相成分导热性能等多因素对导热系数的影响。在常见配比范围内,不同孔隙率下的导热系数预测误差在1.49%~5.94%之间,饱和状态不同砂灰比(骨料含量)下的导热系数预测误差在1.49%~15.26%之间。总体上预测精度较高,涵盖了较大范围配比,满足工程应用和科研需求;同时,该模型预测精度显著高于两种经典的导热系数计算模型,且可通过参数识别得到不同用途水泥基材料的最优参数取值,具有更好的普适性。

For the current situation of less research on thermal conductivity model of cement-based material,in order to provide an applicable method to calculate the thermal conductivity of cement-based materials,the solid-liquid-gas three-phase thermal conductivity prediction model was established according to the composition and the physical structure of the material and using the Fourier’s Law.And parameters were identified based on the cement-based grouts for ground source heat pump,and the parameters and combination of parameters suitable for cement-based grouts were obtained.This model can predict the influence of aggregate content(sand-cement ratio),water-cement ratio(porosity),saturation,thermal conductivity of single-phase components and other factors on thermal conductivity.In the range of common mix ratio,the prediction error of thermal conductivity under different porosity ranges from 1.49%to 5.94%,and the prediction error under different sand-cement ratio in saturated condition is between 1.49%and 15.26%.On the whole,the prediction accuracy is relatively high,covering a wide range of mix ratios,meeting the needs of engineering applications and scientific research.At the same time,the prediction accuracy of this model is significantly higher than that of the classical thermal conductivity calculation models,and the optimal parameter values of cement-based materials for different uses can be obtained through parameter identification,so it has better universality.