Experimental investigation of an organic Rankine cycle with multiple expanders used in parallel

•A novel ORC with multi expanders in parallel (PE-ORC) was proposed for varied heat.•The proposed PE-ORC were experimentally evaluated with two parallel expanders.•Higher performances was achieved in PE-ORC than in a BORC when heat input was low.•Dynamic test led to several control techniques for performance improvement.•The PE-ORC could be one of the competitive design options for large heat variation.

A novel organic Rankine cycle (ORC) with multiple expanders used in parallel (PE-ORC) is proposed for the efficient recovery of waste heat in applications in which there are typically large variations in the amount of heat produced, such as in heavy vehicles and in distributed energy systems with multiple internal combustion engines. The feasibility and the fundamental characteristics of the proposed PE-ORC were experimentally evaluated by establishing an ORC loop with two parallel expanders and testing the performance of the system in different operating modes and in dynamic tests. The PE-ORC was found to be capable of achieving a higher efficiency and a higher total power output than was achieved using a basic ORC configuration when conditions changed from those for which the basic ORC was designed, but the PE-ORC operating mode was changed to suit the new conditions. The proposed PE-ORC could therefore be a better design than is currently available for ORCs that are subject to large variations in the amounts of waste heat produced.