Integrated design of ORC process and working fluid for transient waste-heat recovery from heavy-duty vehicles

Abstract

Organic Rankine Cycles (ORC) transform low- and medium-temperature heat into mechanical power. One promising application of ORCs is the recovery of exhaust gas heat from heavy-duty vehicles. To utilize the full potential of the transient exhaust gas heat, both, the ORC process and working fluid have to be designed. To integrate the working fluid design into the process design, we developed the so-called 1-stage CoMT-CAMD approach, which allows us to identify the optimal combination of ORC process and working fluid. However, 1-stage CoMT-CAMD is limited to steady-state heat input preventing the consideration of the transient exhaust gas behavior. In this work, we propose an iterative algorithm combining 1-stage CoMT-CAMD with time-series aggregation to tackle the challenge of transient exhaust gas behavior, so-called time-resolved 1-stage CoMT-CAMD. By using time-series aggregation, the transient exhaust gas behavior can be represented with sufficient accuracy by a few time steps serving as quasi-steady-state input for 1-stage CoMT-CAMD. The presented algorithm efficiently identifies the optimal working fluid and ORC process while capturing the transient exhaust gas behavior.