Design, modelling and optimisation of a small-scale Solar Organic Rankine Cycle system for rural power generation
Abstract This research study develops the design and model of a Solar Organic Rankine Cycle (SORC) coupled to a bio-digester for small-scale generation in rural areas, in Betulia, Colombia. Moreover, the model is optimised employing a Genetic Algorithm with the software Matlab and the thermodynamic library CoolProp. The objective variables were the mass flow rate of the working fluid, the pressure and temperature of the expander inlet, the solar collectors’ type and the temperature of the water circuit for the bio-digester. The results indicate an overall efficiency between 8.42 and 9.45% with a Levelized Cost of Energy (LCE) between 3.85 and 5.63 £/W. Additionally, the power output is directly related to the mass flow rate of the working fluid. Likewise, increasing the scale of the SORC decreases the LCE. Finally, the results suggest that a superheated fluid reduces the efficiency and the LCE and can deliver more heat to the bio-digester. It is advisable the utilisation of a scroll expander and a counter-flow plate exchanger with a Direct Vapour Generation configuration. The model is a flexible tool capable of integrating more equations and components, with the evaluation of different fitness functions.