Micro humid air turbine cycle – energy and exergy analyses and optimization

Gas turbine applications have an important role in contemporary and
future energy systems. Especially small-scale and alternative fuel fired gas
turbines have high potential. The electric output of a gas turbine cycle can be
increased by adding water after compressor, thereby increasing the flow through
the turbine. Adding water allows for using less combustion air and recuperating
more exhaust heat. On the other hand, significant amount of energy is lost with
water vapour in the exhaust. In this paper, the humid air microturbine concept
with water injection to the saturation tower is evaluated. The aim is to study
how water injection affects the performance and which air and water mass flow
rates should be used for optimized operation. The work is complemented
conducting energy and exergy analyses on the optimized system. Energy analysis
reveals the mechanism of energy recycling, while exergy analysis allows pinpointing
the components that convert useful energy into useless low-level heat.