Deterministic Global Optimization of the Design of a Geothermal Organic Rankine Cycle

Herein, a framework for deterministic global optimization of process flowsheets is adapted to the design of an organic Rankine cycle for geothermal power generation. A case study using isobutane as working fluid is considered for the optimal sizing of components and selection of operating conditions at different ambient temperatures. The framework can provide the global optimum in reasonable calculation times within tight tolerances. In contrast, most local solvers applied are found to be inadequate. The CPU times are substantially smaller compared to a state-of-the-art global solver. For the case considered, recuperation can increase net power output but not necessarily economics.