The ORC systems are typically designed with two heat transfer stages and use a high molecular mass organic working fluid such as butane or pentane. Organic fluid has, compare to water: a lower boiling point, higher vapor pressure, higher molecular mass, and higher mass flow. Together, these features enable higher turbine efficiencies than those offered by a steam system.
- Lower Waste heat source temperature from 150°C (300°F).
- ORCs operate at relatively low pressure: they can operate unattended and fully automated.
- The organic fluid properties avoid blade erosion in the turbine.
- Can utilize air-cooled condensers without negatively impacting the performances of the system.
- ORC equipment is smaller, and the power generation process consists in fewer stages.
- In general, ORC systems are well-matched with small- to medium-size, high-efficiency kilns or kilns with elevated raw material moisture content.
FLOW Diagram of ORC-based power generation system: The first stage transfers heat from the waste gases to an intermediate heat transfer fluid (e.g., thermal transfer oil). The second stage transfers heat from the intermediate heat transfer fluid to the organic working fluid.