Organic Rankine Cycle

The objective is to study the operating characteristics of Organic Rankine Cycle to recover low grade waste heat based on experimental measurements, and computational fluid dynamics (CFD) simulations. Furthermore, study on the selection of working fluid is included.

Design system of Organic Rankine Cycle:

- Operating characteristics of ORC system to recover low grade waste heat: Parametric study of organic Rankine cycle for low-grade heat with temperature below 80oC and small-scale waste heat below 10 kW has been conducted to analyze the effect of operating conditions on the work and efficiency. R245fa was used as a working fluid, and scroll expander was selected as power-generation device. In this study, we present system power and thermal efficiency under various operating conditions, experimentally; evaporating pressure and mass flow rate are main parameters influencing system power and efficiency.

- Expander design: The performance of ORC can be determined depending on the performance of power generation device, i.e. expander. Researchers usually use scroll type expander for small-scale ORC system, and turbo type expander for large-scale ORC system. However, we need to continue to study expander design to increase the performance of the system. We designed rotary engine type expander, and enlarged the operating range.

- Selection of working fluid: The selection of proper working fluid has a great influence on the system operation, and energy efficiency. Due to environmetal reasion, use of hydro-fluorocarbon (HFC) refrigerants was limited, as well. Therefore, it is necessary to find proper working fluid to increase the performance of ORC system.