Papers presented to the 11th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, South Africa, 20-23 July 2015.
Organic Rankine cycles (ORC) are considered a mature
technology in waste heat recovery applications. Yet, many of
the commercially available implementations have comparable
design characteristics. They operate under subcritical regime
and only few working fluids are considered. In this work, three
ORC configurations are analyzed on thermodynamic and
technical grounds. The cycles under consideration are the
subcritical cycle (SCORC), the transcritical cycle (TCORC)
and the partial evaporation cycle (PEORC). Technical design
constraints on the expander generally limit the cycles which can
be considered feasible. Yet, their impact on the optimization
process is not clear. Therefore, in this work, the technical
performance criteria are optimized in conjunction with
maximization of the net power output. Thus the investigation
results in a multi-objective optimization strategy. The proposed
strategy is performed on two representative but distinctive
waste heat recovery cases. The results of the investigation are
particularly useful for manufacturers of ORCs. The
thermodynamic performance of the cycles is compared under
equal boundary conditions, expander criteria are taken into
account, actual cases are used and a ranking is created.
