花岗岩导热系数对裂隙热-流耦合热交换效率的影响研究

The Influence of Thermal Conductivity of Granite on the Heat Exchange Efficiency of Fracture Heat-flow Coupling

针对花岗岩裂隙通道内热-流耦合换热问题,利用有限元软件COMSOL建立二维数值模型,模拟研究花岗岩导热系数对裂隙通道内换热效率的影响,换热效率用换热系数表示。结果显示,随花岗岩导热系数的增大,岩体温度场的变化逐渐变小;随着导热系数的增大,出口水温会越来越高,当出口水温接近热源温度时,变化的趋势逐渐平缓;换热系数随导热系数的增长而变化的过程中存在一个阈值,当导热系数小于阈值时,随着导热系数的增大,换热系数也会增大,当导热系数大于阈值时,随着导热系数的增大,换热系数反而会减小。

Aiming at the heat exchange efficiency of heat-flow coupling in single fracture of granite,a two-dimensional numerical model was established by finite element software COMSOL to simulate the effect of thermal conductivity of granite on the heat exchange efficiency.The heat exchange efficiency was expressed by heat transfer coefficient.The results showed that with the increase of thermal conductivity of granite,the change of temperature field of rock mass decreased gradually.With the increase of thermal conductivity,the water temperature at outlet increased gradually.When the water temperature at outlet was close to the temperature of heat source,the change trend gradually became gentle.The heat exchange coefficient had a threshold value as the thermal conductivity increased.When the thermal conductivity was lower than the threshold,the heat exchange coefficient increased with the increase of thermal conductivity.When the thermal conductivity was greater than the threshold,the heat transfer coefficient decreased with the increase of thermal conductivity.