Organic rankine cycle modelling and the ORCmKit library: analysis of R1234ze(Z) as drop-in replacement of R245fa for low-grade waste heat recovery

Due to the wide interest in organic Rankine cycles (ORCs) as a sustainable technology and the importance of numerical analyses and optimization procedures while considering such systems, we created a dedicated open-source library named “ORC modelling Kit” (ORCmKit). The comprehensive library includes single com-ponents and overall models for subcritical, transcritical and supercritical ORCs. Three main programming environments are currently supported: Matlab, Python and EES (Engineering Equation Solver). A detailed steady-state cycle model of a small-scale regenerative ORC with a single-screw expander is used to evalu-ate the performance influence of R1234ze(Z) as a drop-in replacement of R245fa currently used in the installation. The ORC system is used to recover low-grade waste heat with a temperature range between 90°C and 120°C. A thermal oil heater is used to simulate the heat source. A parametric study is carried out to in-vestigate the performance of the system throughout the range of interest in order to optimize the ORC with R1234ze(Z)

Steady-state and dynamic validation of a parabolic trough collector model using the ThermoCycle Modelica library

© 2018 Elsevier Ltd Small-capacity (<200 kWel) concentrated solar power plants has been recognized as a promising technology for micro power applications. In particular, parabolic trough collectors have been identified as the most promising focusing technology. In this context, physics-based dynamic model of parabolic trough constitutes a significant tool for the further development of the technology, allowing to evaluate and optimize response times during transients, or to implement and test innovative control strategies. In this contribution, the dynamic model of a parabolic trough line based on the ThermoCycle Modelica library is validated against steady-state and transient experimental results from the parabolic trough test loop available at the Plataforma Solar de Almería, Spain. The simulation results are in good agreement with the measurements, both in steady-state and in transient conditions. The validated model is readily usable to investigate demanding dynamics-based problems for low capacity solar power systems.status: publishe