Two-phase expansion
This Royal Academy of Engineering funded research project is exploring next generation waste-heat recovery technologies based on two-phase expansion.
Key project details
- Title: Next-generation waste-heat recovery based on two-phase expansion
- Funder: Royal Academy of Engineering
- Duration: 2019—2024
- Amount: £519,000
- Team: Dr Martin White (Principal Investigator)
Currently, a significant amount of heat is wasted from industrial processes and rejected to the environment. The recovery of this wasted energy would help in improving energy efficiency and achieving net zero. The organic Rankine cycle (ORC) is one of the most promising technologies to convert this wasted energy into electricity. However, the technology is associated with relatively poor thermodynamic performance and high costs.
In conventional ORC systems, the turbine is designed to operate with superheated vapour. This is because the presence of liquid droplets within the turbine could cause damage or erosion. However, power generation from ORC technology could be enhanced by up to 30% if the turbine is operated with a mixture of liquid and vapour. This requires the identification of a suitable turbine that can tolerate two-phase conditions.
- Power improvement due to two-phase expansion (text version)
The image shows the possible improvement in power output when using two-phase expansion for heat source temperatures of 150, 200 and 250 degress Celsius. Improvements can be as high as 30%, but reduce as heat source temperature increases.
Waste-heat recovery power systems can improve energy efficiency, but currently suffer from high costs. This research will explore a novel cycle and turbine design that could lead to a 30% improvement in performance.” Dr Martin White
Senior Lecturer in Mechanical Engineering & RAEng Research Fellow
This project is exploring the possibility of two-phase turbomachinery for this application. This is being completed through a combination of numerical and experimental investigations of two-phase expansion processes, and system optimisation of thermodynamic systems involving two-phase expansion. The aim of this research is to confirm the feasibility of the concept, and to develop understanding of high-speed two-phase expansion processes at a fundamental level.