潘梦绮, 黄权中, 冯榕, 黄冠华. 采用不同监测数据组合反演饱和均质石英砂水热运移参数[J]. 农业工程学报, 2020, 36(10): 75-82. DOI: 10.11975/j.issn.1002-6819.2020.10.009
    引用本文: 潘梦绮, 黄权中, 冯榕, 黄冠华. 采用不同监测数据组合反演饱和均质石英砂水热运移参数[J]. 农业工程学报, 2020, 36(10): 75-82. DOI: 10.11975/j.issn.1002-6819.2020.10.009
    Pan Mengqi, Huang Quanzhong, Feng Rong, Huang Guanhua. Estimation of water and heat transfer parameters of saturated silica sand by using different types of data[J]. Transactions of the Chinese Society of Agricultural Engineering (Transactions of the CSAE), 2020, 36(10): 75-82. DOI: 10.11975/j.issn.1002-6819.2020.10.009
    Citation: Pan Mengqi, Huang Quanzhong, Feng Rong, Huang Guanhua. Estimation of water and heat transfer parameters of saturated silica sand by using different types of data[J]. Transactions of the Chinese Society of Agricultural Engineering (Transactions of the CSAE), 2020, 36(10): 75-82. DOI: 10.11975/j.issn.1002-6819.2020.10.009

    采用不同监测数据组合反演饱和均质石英砂水热运移参数

    Estimation of water and heat transfer parameters of saturated silica sand by using different types of data

    • 摘要: 土壤及含水层的水力参数与热参数对于定量描述土壤水、地下水迁移规律及其伴生的热运移过程十分重要。为探讨不同监测数据类型组合对多孔介质水热参数估计的影响,该研究基于热示踪方法,开展了3种不同粒径条件下的饱和均质石英砂的热示踪试验,并结合HYDRU-2D模型对介质的饱和导水率、导热系数和纵向、横向热弥散度进行反演。参数估计时分别设置3种情景对介质水热参数进行估计:仅采用观测点温度(R1)、观测点温度+水流通量(R2)、观测点温度+水流通量+热量损失(R3)。并对R1情景设置3种不同参数反演组合,即同时对2组参数(饱和导水率和导热系数)、3组参数(饱和导水率、纵向和横向热弥散度)和4组参数(饱和导水率、导热系数、纵向和横向热弥散度)进行估计。研究结果表明:同时对介质饱和导水率、导热系数与热弥散度进行估计,有利于提高介质水热参数的估计精度;对导热系数的合理估计可减小R1情景中介质饱和导水率的估计误差。4组参数中饱和导水率是敏感性最高的参数,增加用于参数反演的水流运动和热量传递信息时,粗砂、中砂、细砂的累积流量相对误差分别减少了9.74、6.65和12.53个百分点,显著提高了介质饱和导水率的反演精度。饱和导水率的估计值随介质粒径增大而增大,而纵向热弥散度随粒径的变化则呈相反的变化规律,横向热弥散度估值基本不变。增加水流和热量传递信息还能显著提高中砂的导热系数反演精度,导热系数的估计值随着介质孔隙度增大而逐渐降低。研究可为基于不同数据类型的均质介质参数反演提供。

       

      Abstract: The hydraulic and thermal parameters of soil and aquifer are very important for quantitative description of soil water, groundwater migration and its accompanying heat and salt transport. In order to investigate the influence of different types of data on the hydraulic and thermal parameter estimation, three heat tracing experiments packed with saturated homogeneous silicon sand of three different particle size (coarse, medium and fine sands) were conducted under steady state. Twenty T-thermocouple probes were installed uniformly in the sandbox to record the temperature of the silicon sand. Two additional T-thermocouple probes were installed in the inflow and outflow chambers to record the water temperature. And then, the measured temperatures of silicon sand and water were applied for the inverses model of HYDRUS-2D software to estimate the saturated hydraulic conductivity, the thermal conductivity and the longitudinal and transverse thermal dispersivity of three saturated silicon sands. In this study, three scenarios based on different types of data were designed to estimate these parameters, i.e. R1 (including the measured temperature at the observation point alone), R2 (including the measured temperature at the observation point and the cumulated outflow) and R3 (including the measured temperature at the observation point, the cumulated outflow and the heat loss). In the addition, three more scenarios under scenario R1 consisted of different numbers of parameters were set, i.e. S1 (the thermal dispersivities were known and the empirical parameters of thermal conductivity and the saturated hydraulic conductivity were estimated); S2 (the thermal conductivities were known and the thermal dispersivity and the saturated hydraulic conductivity were estimated); S3 (the empirical parameters of thermal conductivity, thermal dispersivities and saturated hydraulic conductivity were estimated). The results showed that the thermal conductivity, the longitudinal and transverse thermal dispersivities and the saturated hydraulic conductivity of silicon sand estimated at the same time could significantly improve the accuracy of parameter estimation, and the accuracy of the saturated hydraulic conductivity was improved when the thermal conductivity was reasonable under scenario R1. The saturated hydraulic conductivity was the parameter with the highest sensitivity in parameter estimation, followed by the thermal conductivity and the longitudinal thermal dispersivity. When the simulated temperatures were consistent with the measured temperatures at observation points, there was still 10%-15% estimated error of cumulated outflow. When considering heat loss, wall flow may be the main reason for the estimated error of cumulated outflow. The additional information of water flow and heat loss was helpful to reduce the estimated error of saturated hydraulic conductivity, and then the relative error of cumulated outflow was significantly decreased for coarse, medium and fine sands. The estimated value of saturated hydraulic conductivity increased with the increasing of particle size of silicon sands while the longitudinal thermal dispersivity showed the opposite trend. And the value of transverse thermal dispersivity was same for all the sands. The additional information of water flow and heat loss improved the estimation of thermal conductivity of medium sand as well. The estimated value of thermal conductivity decreased with increasing particle size of silicon sands. This study can help for parameter estimation of homogeneous porous media based on different type of data.

       

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