Design, improvements and applications of dual-pressure evaporation organic Rankine cycles: A review

Renewable energy utilization and waste heat recovery are important ways to achieve the carbon neutral goal. However, lots of renewable energy and waste heat belong to medium-to-low temperature (<350 °C) thermal energy, and conventional power technologies are not applicable. Organic Rankine cycle (ORC) is a new power technology with low-boiling organic fluid as working fluid, achieving an efficient heat-power conversion for medium-to-low temperature thermal energy. High conversion efficiency is crucial to the commercial promotion of ORC technology. As an emerging cycle type of ORC, dual-pressure evaporation cycle can further substantially increase conversion efficiency. Meanwhile, it has better applicability to heat sources with complex heat release characteristics and substantial fluctuations. Its outstanding advantages have attracted lots of scholars, and related papers are proliferating in recent years. However, scattered researches seriously hinder the systematic cognition of scholars and the progress of dual-pressure evaporation ORC. This paper systematically reviews the research status of dual-pressure evaporation ORC. System arrangements, process characteristics, component layouts, and suitable scenarios of typical dual-pressure evaporation ORCs are introduced. Cycle structure improvement approaches and potential application fields are summarized, and the off-design operation characteristics are also analyzed. On this basis, future research focuses of dual-pressure evaporation ORC are discussed. This review can promote the theoretical development and practical applications of dual-pressure evaporation ORC, accelerating the large-scale development of renewable energy and waste heat.