Employing Micro-Turbine Components in Integrated Solar-MGT-ORC Power Plants

The authors propose in this paper the integration of a combined power plant, with a micro gas turbine (MGT) and an ORC system, and a solar field that allows a temperature increase of the air at the MGT recuperator inlet. Consequently, an increase is also obtained for the exhausts and this leads to an enhanced heat recovery in the ORC boiler and a greater availability of thermal energy. The purpose of the authors’ work is to analyze the effectiveness of the above proposal under several aspects, therefore, under a preliminary thermodynamic study of the plant set-up in CHP mode, the attention is paid to the choice of the organic fluid expander with a low-cost objective. Classical similarity criteria are helpful for a first estimate of the adaptability of a radial flow turbine from the down-sized turbocharger technology to an organic working fluid. A CFD validation of such choice is then carried out and this phase also determines the characteristic curves of the radial flow turbine. Basing on the availability of the characteristic maps of all the rotating components, a reliable off-design analysis of the solar-assisted CHP plant is performed under several load levels and environmental conditions, the latter strongly influencing the solar irradiance on the parabolic trough collectors. Finally, since the examples refer to both natural gas and biogas fuelling, a CFD analysis of the reacting flow through the MGT combustor checks the combustion effectiveness under challenging variations of the boundary condition