This paper investigates the design and thermodynamic optimisation of both sub- and transcritical organic Rankine cycle (ORC) power systems featuring radial turbines via performance calculations using mean-line models. The emphasis is on rapid performance predictions for a given turbine geometry, as well as geometric optimisation for a given heat source. From three specified quantities, which are the turbine inlet temperature, inlet pressure and mass flow rate, the other flow properties (e.g., outlet pressure and temperature) are computed, together with derived quantities which are required for cycle- or system-level assessments, such as the isentropic efficiency of the turbine. Experimental investigations from the open literature suitable for validation purposes are summarised and analysed with respect to their strengths and weaknesses. Similar computational fluid dynamic (CFD) simulations are also used to complement the available experimental data. The main contributions of this paper are that it provides a comprehensive overview of radial turbine performance modelling, and that it proposes a detailed framework that can be used for the improved development of efficient thermodynamic power systems based on a unified mean-line model that is validated against experimental data and supported by CFD results. Specifically, predictions from the mean-line model show good accuracy over a wide range of operating conditions for different turbine designs and fluids with compressibility factors from 0.6 - 1.0. Finally, in order to demonstrate its efficacy, the integrated radial turbine and ORC system design framework is used in a case study of a nominally 400-kW power system with propane as the working fluid in low-grade waste-heat application, where the turbine inlet temperature is fixed at 150 ° C and the condenser temperature is fixed at 15 ° C. The novelty of this work arises from the optimisation of the turbine nozzle vane position at off-design conditions. This feature, along with multi-stage radial turbine designs are shown to allow high-performance operation over a wide range of off-design conditions. Specifically, good efficiencies are demonstrated over a wide range of heat-source fluid flow rates when employing an adjustable nozzle geometry, as is the ability of radial turbines to achieve efficiencies that are not constrained by the pressure ratio across them by replacing single-stage designs with multi-stage designs.

本文通过使用均线模型进行性能计算，研究了具有径向涡轮的亚临界和跨临界有机朗肯循环（ORC）电力系统的设计和热力学优化。重点是针对给定的涡轮几何形状的快速性能预测，以及给定热源的几何优化。根据三个指定的量，即涡轮机入口温度，入口压力和质量流量，计算其他流量特性（例如，出口压力和温度），以及进行循环或系统级评估所需的导出量，例如涡轮的等熵效率。总结并分析了公开文献中适合验证目的的实验研究的优缺点。类似的计算流体动力学（CFD）模拟也用于补充可用的实验数据。本文的主要贡献在于，它提供了径向涡轮机性能建模的全面概述，并提出了一个详细的框架，该框架可用于经过验证的统一均线模型，以改进高效热力动力系统的开发。根据实验数据并得到CFD结果的支持。具体而言，根据平均线模型的预测表明，对于不同的涡轮机设计和可压缩系数为0.6-1.0的流体，在各种工况下均具有良好的精度。最后，为了证明其功效，集成的径向涡轮机和ORC系统设计框架用于标称400 kW电力系统的案例研究，该系统以丙烷为低等级废热应用的工作流体，其中涡轮机入口温度固定在150°C，冷凝器温度固定在15°C。这项工作的新颖之处在于优化了非设计条件下的涡轮喷嘴叶片位置。该功能以及多级径向涡轮机设计可在各种非设计条件下实现高性能运行。具体而言，当采用可调喷嘴几何形状时，在宽范围的热源流体流速下都表现出良好的效率，