Add to ORKGSophisticated designs of thermal systems may be evaluated, quickly and inexpensively, with the support of computer based system simulation techniques; i.e. CAD for thermal systems. Furthermore, the response of a thermal system to predicted periodic and transient loads and the resulting interactions between system components may be assessed. A thermal energy system simulation code is utilized and expanded to predict the performance of an industrial Rankine cycle (steam turbine) cogeneration plant having mutually varying electrical, process steam and space heating loads. Results are presented to show the effect of variation in the electricity-to-steam ratio and extraction pressure for process steam requirements on system performance