Expander design procedures and selection criterion for small rated organic rankine cycle systems

The particular aspect of this work is the new approach to expander design procedurefor small rated ORC. In fact, once all the calculation procedures have been defined,they have been implemented in Matlab code. This code, once the design process iscomplete, provides an indication of the optimal expander configuration to adoptingto that specific system. For these reasons, this paper aims to analyze all the preliminaryexpanders' design procedures, both dynamic and volumetric. The reasons lie inthe development of low-enthalpy heat recovery systems (systems that allow simultaneousproduction of electrical and thermal energy made available in the form ofwater at a temperature of 60-90°C), with the aim of optimizing any energy system.Within these energy systems, the expander is the main component, responsible forpower generation. It is, therefore, necessary and useful to analyze in detail everyexpander configuration, highlighting the different features. For each component willbe described the theory on which is based the choice and its design and a possiblesoftware implementation is supplied. Finally, a criterion for the choice of the optimalexpander is proposed, based on some operational considerations and other constructionand structural constraints, such as overall dimensions and weight, lubrication,MTBF, feasibility, reliability, and coupling with the electric generator