Approximate analysis of the economic advantage of a dual source ORC system over two single ORC systems in the conversion of dual low and mid grade heat energy to electricity.

An approximate economic analysis reported in this paper shows that in a novel dual source ORC system where a low-grade heat source is used to preheat and vapourise the working fluid and mid-grade heat source is used to provide the superheating, the payback period is very much smaller than when the two heat sources are used separately to drive a single ORC system. The simulation results shows that on the same waste heat basis, the size of the heat exchangers and the quantity of working fluid used for the dual source ORC is smaller than the cumulative heat exchangers size and refrigerant quantity used for the two single ORC systems.