mixedcycle

Mixedcycle is a term used to describe systems that employ two or more thermodynamic cycles within a single plant, process, or equipment to utilize energy more efficiently. The phrase is not standardized across industries, and its precise meaning can vary depending on the field and author. In general, a mixed-cycle configuration seeks to combine the strengths of distinct cycles to improve overall performance, flexibility, or fuel efficiency.

In power generation, mixed-cycle configurations often involve coupling a high-temperature cycle, such as a gas-turbine Brayton cycle, with a lower-temperature cycle, such as a steam Rankine cycle, through a heat-recovery interface. In many cases this is essentially a combined-cycle plant; elsewhere the term is used to denote additional bottoming cycles, such as an organic Rankine cycle (ORC) or a secondary refrigeration loop, integrated to extract residual heat or drive auxiliary processes. The objective is to convert a larger portion of the fuel's energy into electrical or mechanical power across a wider load range.

Outside power plants, mixed-cycle concepts appear in refrigeration, chemical processing, and energy systems where multiple cycles are concurrently run to recover waste heat, optimize temperature bands, or enable fuel flexibility. For example, multi-cycle refrigeration or mixed refrigerant cycles mix elements of different thermodynamic loops to achieve desired cooling characteristics.

Benefits of mixed-cycle approaches include higher overall efficiency, better part-load performance, and reduced emissions. Drawbacks can include increased capital cost, more complex control and maintenance, and higher sensitivity to component matching and heat-exchanger design.

See also: combined cycle, heat recovery, organic Rankine cycle, waste heat recovery, multi-cycle systems.