花岗岩单裂隙渗流传热特性试验

基于岩石裂隙渗流传热试验系统，以蒸馏水为换热工质，针对预制平滑裂隙与粗糙裂隙的花岗岩岩样，开展不同试验温度与水流条件下的单裂隙对流换热特性试验研究。试验结果表明：①同一温度水平下，对流换热系数的量值与流量呈正相关关系，但对流换热系数的增幅大于流量的增幅，随岩石基质温度的升高，相同流量水平下的对流换热系数呈增大趋势；②与平滑裂隙试验结果相比，粗糙裂隙面的对流换热强度有所提高，但增幅不大；③沿渗流路径，裂隙面局部对流换热强度的演化呈现多波峰的非线性特征，其中粗糙裂隙的非线性更加强烈。但二者均存在由进水口至出水口，换热强度逐渐减弱的特征。④努塞尔数与普朗特数1/3次方的商与雷诺数较好地满足幂指数关系，随着试验温度的升高，这种关系逐渐向线性转变。

Experiment on convection heat transfer characteristics in a single granite fracture

Convection heat transfer in a single granite fracture was experimentally investigated in this work. Distilled water was used as working medium for heat transfer in manmade smooth and rough fractures of granite samples. The influence of fracture roughness on heat transfer intensity was analyzed. The evolution of external surface temperatures of rock samples was monitored using resistance temperature detectors during seepage heat transfer to study the local heat transfer characteristics along the seepage path. Subsequently, the heat transfer correlations were summarized on the basis of the experimental results. Main conclusions are as follows: (1) under a given temperature level, the convection heat transfer coefficient features a positive correlation with flow rates. The increase rate of heat transfer coefficient is greater than the flow rates. Under a given flow rate, the convection heat transfer coefficient increases with the increase of experimental temperature. (2) the roughness of rock fracture increases the local heat transfer intensity to a certain extent, but the enlargement is not big. (3) the external surface temperatures exhibit nonlinear characteristic with multiple peaks, the temperature evolution history of rough fracture are more complicated than smooth fracture. For both smooth and rough fracture, the heat transfer intensity decreases with the distance to the inlet. (4) the quotient of Nusselt number and the 1/3 power of Prandtl number is close to a power function of Reynolds number under the experimental conditions in this work. With the increase of experimental temperature, the relationship gradually tends to be linear.