Dynamic modeling and optimization of an ORC unit equipped with plate heat exchangers and turbomachines

In the current research activity, a dynamic model of an ORC system was developed in a commercial 1D Computer Aided Engineering software platform. Sub-models of the two plate heat exchangers and of the multi-stage centrifugal pump were developed and calibrated using performance data of industrial components at design and off-design conditions. On the other hand, the R245fa radial turbine design was accomplished using a design procedure that provided geometrical and performance data for the mapping of the device by means of a 1D tool. A steady-state off-design analysis at different operating conditions at the evaporator was further carried out optimizing pump and turbine speeds to maximize the net power output. Furthermore, the thermal inertial effects at the evaporator were assessed with reference to a sample heat load profile of the water hot source and at different time scales.