废旧轮胎-砂颗粒轻质填料导热特性及预测模型

Thermal conductivity and prediction model of waste tire-sand particle lightweight filler

为了研究废旧轮胎-砂颗粒轻质填料的导热系数特性,降低废旧轮胎颗粒对地下散热构筑物的热量累积影响,采用室内热探针测试技术与电镜扫描技术,分析了含砂率、含水率、干密度和粒径对废旧轮胎-砂轻质填料导热系数的影响,以及废旧轮胎-砂轻质填料的微观传热机理,提出了简化的废旧轮胎-砂导热系数多元线性回归预测模型.结果表明:废旧轮胎-砂轻质填料导热系数随含水率增加可分为增长区和稳定区,且临界含水率(质量分数)达到6%;砂粒径越大,废旧轮胎-砂轻质填料导热系数越大;当含砂率(体积分数)小于40%时,废旧轮胎-砂轻质填料导热系数随干密度增加呈抛物线增长;当含砂率大于60%时,废旧轮胎-砂轻质填料导热系数随干密度增加呈线性增长;废旧轮胎-砂颗粒轻质填料的主导传热连,随着含砂量的增加,由橡胶-橡胶传热链向砂-砂传热链转变.废旧轮胎-砂颗粒轻质填料导热系数回归预测模型具有良好的精度,能够为轻质回填料中的热构筑物周围温度场的分析提供更加合理的热学参数.

In order to study the thermal conductivity of waste tire-sand lightweight fillers and reduce the influence of waste tire particles on the heat accumulation of underground heat dissipating structures,the effects of sand content,moisture content,dry density and particle size on the thermal conductivity of waste tire-sand lightweight fillers and the micro-heat transfer mechanism were analyzed by the indoor thermal probe test technology and electron microscope scanning technology.A simplified multivariate linear regression model for predicting the thermal conductivity of waste tire-sand lightweight fillers was proposed.The results show that the thermal conductivity of waste tire-sand lightweight filler can be divided into the growth zone and stable zone with the increase in moisture content,and the critical moisture content reaches 6%;the larger the sand size,the higher the thermal conductivity of waste tire-sand lightweight filler;when the sand content is less than 40%,the thermal conductivity of waste tire-sand lightweight filler is observed to be a parabolic increase with the increase in dry density;when the sand content exceeds 60%,the thermal conductivity of waste tire-sand lightweight filler is observed to be a linear increase with the increase in dry density;the dominant heat transfer chain of the waste tire-sand particle lightweight filler changes from the rubber-rubber heat transfer chain to the sand-sand heat transfer chain with the increase in sand content.The regression prediction model of thermal conductivity of the waste tire-sand particle lightweight filler shows good accuracy,which can provide more reasonable thermal parameters for the analysis of temperature field around thermal structures in lightweight backfills.