热管型地热系统气液分离器外部流场结构优化

Optimization of External Flow Field Structure of Gas-liquid Separator in Geothermal System Heat Pipe

超长重力热管开采地热能的过程中,热管中下降的冷凝液与上升的热蒸汽易相互碰撞而引发蒸汽带液情况,通过在绝热段增设气液分离器可有效预防这一问题。介绍了新型热管型地热系统中气液分离结构(气液分离器)的特点,采用计算流体力学方法,建立了气液分离器有限元模型并对其外部流场进行模拟。通过在分离器外部空腔内设置螺旋导流板,调节气液分离器入口管高度、偏心距及螺旋导流板板螺数、螺距,进行优化分析研究。设置螺旋导流板后,液体在分离器出口处的流动更加稳定,冷凝水入口与气液分离器出口距离与压降成正比关系,入口管偏心距与内管内壁面切应力成反比关系。螺旋导流板螺数为5、螺距为200 mm时分离器出口液体的均匀性和稳定性最优。

In the process of exploiting geothermal energy using a super-long gravity heat pipe,the descending condensate and ascending hot vapor in the heat pipe are prone to collide with each other and cause liquid carryover.This issue can be effectively prevented by adding a gas-liquid separator in the adiabatic section.The characteristics of the gas-liquid separation structure(gas-liquid separator)in the new heat pipe-type geothermal system were introduced,the finite element model of the gas-liquid separator was established and its external flow field was simulated by using computational fluid dynamics method.Optimization analysis was carried out by setting a spiral deflector in the external cavity of the separator and adjusting the height and eccentricity of the inlet tube of the gas-liquid separator,as well as the number and pitch of screws of the spiral deflector plate.After setting the spiral deflector,the liquid flow at the outlet of the separator is more stable,the distance between the condensate inlet and the outlet of the gas-liquid separator is proportional to the pressure drop,and the eccentricity of the inlet tube is inversely proportional to the shear force on the inner wall of the inner tube.The uniformity and stability of the liquid at the outlet of the separator are optimal when the number of screws of the spiral deflector is 5 and the pitch is 200 mm.