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Dynamic test and verification of model-guided ORC system

Zhang, Ying, Deng, Shuai, Zhao, Li, Lin, Shan, Bai, Mengjie, Wang, Wei, Zhao, Dongpeng
Energy conversion and management 2019 v.186 pp. 349-367
computer software, dynamic models, evaporation, heat, mass flow, simulation models, temperature, uncertainty
This paper aims to reveal the coupling correlation of the ORC related system, and verify the boundaries and feasibilities of the system-level modeling. A kW-scale ORC test rig with a self-made expansion valve is set up for the dynamic test under three common freedoms, namely the mass flow rate of working fluid, heat source and cooling source. By imposing the same real-time experimental conditions, the system-level dynamic simulation is performed on the Modelica/Dymola software. The test rig and dynamic model are of high-accuracy and reliable after examining the heat balances and error propagation of the measurement uncertainties, as well as calibrating with theoretical analysis. Results show that the internal disturbance of mass flow rate of working fluid significantly affect the states parameters. The external disturbance of mass flow rate of cooling source has a less effect on the states parameter, while the states parameters are insensitive to the external disturbance of mass flow rate of heat source. The simulation results are in agreement with the experimental results. The average overshoot of the outlet temperature of cooling source is 0.7 °C, and the average overshoot of the evaporation pressure is 48 kPa, which coincide with the results from the experiment under the disturbance of working fluid mass flow rate. It shows the potential of such simulation model to be a guided model, which also predicts that the maximum desired power output of the ORC test rig is about 1874.7 W, with the thermal efficiency of 6.94%.