Thermodynamic analysis and optimization of organic Rankine cycles based on radial-inflow turbine design
Thermodynamic analysis and optimization of organic Rankine cycles based on radial-inflow turbine design
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DOI：
10.1016/j.applthermaleng.2020.116277
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发表时间：
2020-11
影响因子：
6.4
通讯作者：
Yunyuan Li;Wenyu Li;Xinyue Gao;X. Ling
中科院分区：
文献类型：
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作者：
Yunyuan Li;Wenyu Li;Xinyue Gao;X. Ling
近年来，热源温度超过300 °C的高温有机朗肯循环（ORC）引起了人们的兴趣，从工业角度来看，它具有广泛的应用前景。然而，很少有研究人员关注高温ORC系统和径向流入涡轮机（RIT）的耦合设计和优化。在这项工作中，ORC系统和RIT的耦合设计的热源入口温度为300，350和400 °C的开发使用非支配排序遗传算法。引入ORC热效率和涡轮机性能因子（PF）作为优化目标。两种混合物的硅氧烷，七个纯硅氧烷和九个纯烃被认为是工作流体的候选人。此外，硅氧烷的混合物和纯工质之间的热力学比较。此外，研究了涡轮机入口总温度、总静态膨胀比和比转速对ORC热效率、涡轮机性能和涡轮机尺寸的影响。结果表明，膨胀比对涡轮机输出功率和循环热效率影响较大，而涡轮机尺寸对涡轮机进口总温和比转速影响较大。此外，PF随涡轮机进口总温、膨胀比和比转速的升高而增大。此外，与纯工作流体相比，硅氧烷的混合物具有更高的效率，但是更大的涡轮机和热交换器尺寸。具有更高PF和更小尺寸的涡轮机和换热器的环己烷、甲苯、间二甲苯和己烷在优选紧凑型涡轮机和换热器的应用中是有希望的工作流体，例如车辆废热回收。
In recent years, high-temperature organic Rankine cycle (ORC) with a heat source temperature over 300 °C has attracted interests, which has wide range of applications from industrial point of view. However, few researchers have focused on the coupled design and optimization of the high-temperature ORC system and radial-inflow turbine (RIT). In this work, a coupled design of the ORC system and RIT with the heat source inlet temperatures of 300, 350 and 400 °C is developed using non-dominated sorting genetic algorithm. The ORC thermal efficiency and turbine performance factor (PF) are introduced as optimization objectives. Two mixtures of siloxanes, seven pure siloxanes and nine pure hydrocarbons are considered as working fluid candidates. In addition, the thermodynamic comparison between mixtures of siloxanes and pure working fluids is presented. Moreover, the influences of the turbine inlet total temperature, total-to-static expansion ratio, and specific speed on the ORC thermal efficiency, turbine performance, and turbine size are investigated. The results show that the turbine power output and cycle thermal efficiency are more sensitive to the expansion ratio while turbine size is more sensitive to the turbine inlet total temperature and specific speed. In addition,PFincreases with the rise of the turbine inlet total temperature, expansion ratio and specific speed. Moreover, compared with pure working fluids, mixtures of siloxanes have higher efficiencies, but larger turbine and heat exchanger size. Cyclohexane, toluene, m-xylene and hexane with higherPFand smaller size of turbine and heat exchanger are promising working fluids in applications where the compact turbine and heat exchanger is preferred, such as vehicle waste heat recovery.