Design Performance Analysis of Micro Gas Turbine-Organic Rankine Cycle Combined System

This study analyzes the design performance of a combined system of a recuperated cycle micro gas turbine (MGT) and a bottoming organic Rankine cycle (ORC) adopting refrigerant (R123) as a working fluid. In contrast to the steam bottoming Rankine cycle, the ORC optimizes the combined system efficiency at a higher evaporating pressure. The ORC recovers much greater MGT exhaust heat than the steam Rankine cycle (much lower stack temperature), resulting in a greater bottoming cycle power and thus a higher combined system efficiency. The optimum MGT pressure ratio of the combined system is very close to the optimum pressure ratio of the MGT itself. The ORC's power amounts to about of MGT power. For the MGT turbine inlet temperature of or higher, the combined system efficiency, based on shaft power, can be higher than .