地热能全流发电用两相单螺杆膨胀机理论膨胀过程热力特性研究  

Study on the Thermal Characteristics of a Two-Phase Single-Screw Expander for Total-Flow Geothermal Power Generation

作　　者：聂涛[1] 周宏洋 邵华 王增丽[1] NIE Tao;ZHOU Hongyang;SHAO Hua;WANG Zengli(College of New Energy,China University of Petroleum(East China),Qingdao,Shandong 266580,China)

机构地区：[1]中国石油大学(华东)新能源学院,山东青岛266580

出　　处：《西安交通大学学报》2024年第5期190-199,共10页Journal of Xi'an Jiaotong University

基　　金：国家自然科学基金资助项目(52376020,52176029);山东省自然科学基金资助项目(ZR2022ME114)。

摘　　要：针对地热能发电技术存在的系统效率与热源利用率低的问题,对全流循环发电系统中替代传统汽轮机使用的单螺杆膨胀机进行了热力特性分析。基于质量守恒方程、能量守恒方程与湿蒸汽维里状态方程,建立了考虑液体闪蒸与气液平衡的单螺杆膨胀机理论全流膨胀过程的热力学模型,探索了进气温度与干度对气液两相工质状态及膨胀机热力特性的影响机理。结果表明:当进气温度由140℃升高至170℃时,湿蒸汽工质的质量、压力和温度均得到提升,单螺杆膨胀机的输出功率也由210 kW提升至约260 kW,等熵效率在进气温度为160℃时取得77%的最佳值;进气干度的提高会减少进入工作腔湿蒸汽工质质量,进而导致膨胀结束后介质压力与温度的降低,但显著促进了膨胀机的性能参数包括输出功率和等熵效率的提高,当进气干度为0.3时,单螺杆膨胀机的输出功率超过了500 kW,等熵效率也可达76.5%。上述研究结果对应用于地热能全流发电的两相单螺杆膨胀机的热力特性分析与改善以及全流发电技术的优化有一定的参考意义。In response to the low system efficiency and heat source utilization in geothermal power generation technology,the thermal characteristics of a single-screw expander used in a total-flow cycle power generation system as an alternative to the traditional steam turbine are analyzed.Based on the mass and energy conservation equations and wet-steam virial equation of state,a thermodynamic model is formulated for the total-flow expansion involving liquid flash and vapor-liquid equilibrium.The influence of inlet temperature and dryness on the state of vapor-liquid two-phase working medium and the thermal characteristics of the expander is examined.The results show that elevating the inlet temperature from 140℃to 170℃enhances the mass,pressure,and temperature of the wet steam working medium,and the output power of the single-screw expander rises from 210 kW to about 260 kW,with the isentropic efficiency becoming optimal at 77%at the inlet temperature of 160℃.Improving the inlet steam dryness diminishes the quality of the working medium of the wet steam entering the working chamber,causing a subsequent reduction in medium pressure and temperature after the expansion.However,this significantly boosts expander performance parameters,including output power and isentropic efficiency.With an inlet steam dryness of 0.3,the output power of the single screw expander exceeds 500 kW,and the isentropic efficiency reaches 76.5%.The study outcomes provide reference for the analysis and improvement of thermal characteristics of a two-phase single-screw expander used for geothermal energy total-flow power generation,as well as the optimization of total-flow power generation technology.

关 键 词：地热能 两相湿蒸气 单螺杆膨胀机 热力特性 

分 类 号：TB653[一般工业技术—制冷工程]