FUNDAMENTAL STUDIES ON ORGANIC RANKINE CYCLE EXPANDERS (NextORC)

商业蒸汽发电厂对水加压加热以产生蒸汽，然后蒸汽膨胀以产生电力。然而，使用有机流体可以使低温热源（通常在80到350摄氏度之间）比蒸汽更经济地转化为机械动力。因此，有机朗肯循环（ORC）具有巨大的潜力，可以为英国的低碳技术组合做出贡献，这些技术具有前景广阔的应用，如热电联产、集中太阳能发电、往复式发动机的废热回收以及其他利用废热流的工业过程。然而，尽管orc在工业规模应用方面成功商业化，但在实现其潜力之前，需要在商业和家庭规模上进行更多的发展。更具体地说，在这些小规模中，挑战在于设计效率高但成本低的系统。实现这一目标的一种方法是开发在一系列不同条件下有效运行的系统。这将使ORC系统的大批量、低成本生产成为可能，从而显著提高规模经济效益。此外，在这种规模下，可以考虑不同的膨胀器技术，如涡轮膨胀器和螺旋膨胀器，以及系统架构。然而，目前尚不清楚哪种扩展器技术或系统架构是实现规模经济所需改进的最佳选择。为了回答这个问题，重要的是要提高对不同ORC膨胀器在各种操作条件下的表现的理解，并研究这些系统如何响应工作流体的变化。本提案的重点是进行原创性研究，以提高对两种不同类型的ORC膨胀机（涡轮膨胀机和螺杆膨胀机）性能的基本认识。计算和实验方法将用于研究这些膨胀器在各种操作条件下和各种有机流体中的性能。这些研究必须考虑到有机流体的复杂性，这些有机流体表现出在空气和蒸汽等常规流体中观察不到的复杂流体行为，此外还要考虑高速流动和涡轮膨胀机和螺旋膨胀机中预期的两相条件。最终，这些研究的结果将改进现有的科学认识，并将促进这些膨胀器的新性能预测方法的发展。了解这些方面不仅可以改进性能预测，还可以改进将来的组件设计。在这个项目中，新的预测方法将用于调查和比较不同ORC系统架构中不同扩展器的性能。这些比较的结果将能够确定可以在广泛的操作条件下运行的最佳系统，从而最好地促进小规模ORC系统规模经济的改进。本研究的主要成果将是提高对ORC膨胀器性能的基本理解，并验证涡轮和螺杆膨胀器的性能模型。此外，还将就最适当的系统配置提出建议，以改善规模经济，从而加强今后小型ORC技术的商业化。因此，该项目有可能刺激投资，并在低碳能源市场创造新的就业机会，同时对英国现有的涡轮机械和螺旋膨胀机研究组合做出积极贡献。

Commercial steam power plants pressurise and heat water to produce steam which is then expanded to produce electricity. However, using an organic fluid permits low temperature heat sources, typically between 80 and 350 degrees Celsius, to be converted into mechanical power more economically than steam. Organic Rankine Cycles (ORC) therefore have a great potential to contribute to the UK's mix of low carbon technologies with promising applications such as combined heat and power, concentrated solar power and waste heat recovery from reciprocating engines and other industrial processes with waste heat streams. However, despite successful commercialisation of ORCs for industrial scale applications, more development is required at the commercial and domestic scales before its potential can be realised. More specifically, at these small-scales, the challenge lies in the design of systems that are efficient but are also low cost. One approach to achieving this is to develop systems that operate efficiently over a range of different conditions. This will enable the high-volume, low-cost production of ORC systems, enabling significant improvements in the economy-of-scale. Furthermore, at this scale, different expander technologies, such as turbo and screw expanders, and system architectures can be considered. However, it is not clear which expander technology or system architecture is the optimal choice to achieve the desired improvements in the economy-of-scale. To answer this question it is important to improve the understanding of how different ORC expanders perform across a wide range of operating conditions, and to investigate how these systems respond to changes in the working fluid.The focus of this proposal is to conduct original research to improve the fundamental understanding on the performance of two different types of ORC expander, namely turbo and screw expanders. Computational and experimental methods will be used to investigate the performance of these expanders across a wide range of operating conditions and with a variety of organic fluids. These studies must account for the complexities of using organic fluids that exhibit complex fluid behaviour not observed in conventional fluids such as air and steam, in addition to considering the high speed flows, and two-phase conditions that are expected in turbo and screw expanders respectively. Ultimately, the results from these studies will improve the existing scientific understanding, and will facilitate the development of new performance prediction methods for these expanders. Understanding these aspects will not only lead to improved performance prediction, but could also lead to improved component design in the future. Within this project the new prediction methods will be used to investigate and compare the performance of different expanders within different ORC system architectures. The results from these comparisons will enable the identification of the optimal systems that can operate across a wide range of operating conditions, and therefore best facilitate improvements in the economy-of-scale of small-scale ORC systems.The primary outcomes of this research will be improved fundamental understanding of the performance of ORC expanders and validated performance models for turbine and screw expanders. Furthermore, recommendations will be made on the most appropriate system configurations that offer improvements in the economy-of-scale, thus enhancing the future commercialisation of small-scale ORC technology. Therefore this project has the potential to stimulate investment and create new jobs within the low carbon energy market, whilst positively contributing to the UK's existing research portfolio in turbomachinery and screw expanders.