EGS (Enhanced Geothermal System) is a potential way to utilize geothermal energy efficiently. In present work, a three-dimensional physical model, a single fracture with undulated surface morphology in hot dry rock is constructed. Supercritical CO₂ is used as working fluid, and its convection heat transfer characteristics in fracture is numerically investigated. The influence of flow rate, inlet temperature, and reservoir pressure on convection heat transfer are probed. The results indicate that the local convection heat transfer coefficients at upper wall and lower wall of fracture show opposite variation trend at corresponding positions, and it varies with the undulation of surface morphology. In addition, the local convection heat transfer coefficients rise with the decrease of flow rate, the increase of pressure and inlet temperature. Furthermore, the correlation of normalized convection coefficient Nusselt number of supercritical CO₂ in fracture is obtained.

EGS（增强型地热系统）是有效利用地热能的一种潜在方法。在目前的工作中，建立了一个三维物理模型，即热干岩石中具有起伏表面形态的单个裂缝。超临界CO ₂将其用作工作流体，并对其在裂缝中的对流传热特性进行了数值研究。探讨了流速，入口温度和储层压力对流传热的影响。结果表明，裂缝上壁和下壁的局部对流换热系数在相应位置呈相反的变化趋势，并随表面形态的波动而变化。另外，局部对流换热系数随着流量的减小，压力和入口温度的增加而增加。此外，获得了裂缝中超临界CO ₂的标准化对流系数Nusselt数的相关性。