A review of scroll expanders for organic Rankine cycle systems

•Several types of scroll expanders used in ORC systems are reviewed.•Some key factors that affect the expander efficiency are discussed.•Theoretical models for predicting the expander performance are summarized.•CFD can play a vital role in optimal design of scroll expanders.

In the field of low-grade heat energy utilization, organic Rankine cycle (ORC) has gained enough worldwide attention in recent years. Scroll expander has become a good candidate for micro and small-scale ORC applications because of its reliability, compact structure, fewer moving parts, lower level of noise and vibration. This paper reviews the relevant research studies for getting insight into the application and research status of the scroll expander applied to ORC, including its technical features, performances and the main technical limitations existing in application. Available simulation methods for investigating and optimizing the scroll expander performance are also summarized and discussed, which would be beneficial for designing high efficiency scroll expanders for ORC systems.