A Rankine cycle system comprising: (a) a first heater configured to transfer heat from a first waste heat-containing stream to a first working fluid stream to produce a first vaporized working fluid stream and a second waste heat-containing stream; (b) a first expander configured to receive the first vaporized working fluid stream to produce therefrom mechanical energy and an expanded first vaporized working fluid stream; (c) a first heat exchanger configured to transfer heat from the expanded first vaporized working fluid stream to a first condensed working fluid stream to produce therefrom a second vaporized working fluid stream; (d) a second expander configured to receive the second vaporized working fluid stream to produce therefrom mechanical energy and an expanded second vaporized working fluid stream; (e) a second heat exchanger configured to transfer heat from the expanded second vaporized working fluid stream to a second condensed working fluid stream, to produce therefrom a first stream of the working fluid having greater enthalpy than the second condensed working fluid stream; (f) a second heater configured to transfer heat from a waste heat-containing stream to a third condensed working fluid stream to produce a second stream of the working fluid having greater enthalpy than the third condensed working fluid stream; and (g) a working fluid stream combiner configured to combine the first stream of the working fluid having greater enthalpy than the second condensed working fluid stream with the second stream of the working fluid having greater enthalpy than the third condensed working fluid stream, to produce the first working fluid stream. (a) a first heater configured to transfer heat from a first waste heat-containing stream to a first working fluid stream to produce a first vaporized working fluid stream and a second waste heat-containing stream; (b) a first expander configured to receive the first vaporized working fluid stream to produce therefrom mechanical energy and an expanded first vaporized working fluid stream; (c) a first heat exchanger configured to transfer heat from the expanded first vaporized working fluid stream to a first condensed working fluid stream to produce therefrom a second vaporized working fluid stream; (d) a second expander configured to receive the second vaporized working fluid stream to produce therefrom mechanical energy and an expanded second vaporized working fluid stream; (e) a second heat exchanger configured to transfer heat from the expanded second vaporized working fluid stream to a second condensed working fluid stream, to produce therefrom a first stream of the working fluid having greater enthalpy than the second condensed working fluid stream; (f) a second heater configured to transfer heat from a waste heat-containing stream to a third condensed working fluid stream to produce a second stream of the working fluid having greater enthalpy than the third condensed working fluid stream; and (g) a working fluid stream combiner configured to combine the first stream of the working fluid having greater enthalpy than the second condensed working fluid stream with the second stream of the working fluid having greater enthalpy than the third condensed working fluid stream, to produce the first working fluid stream.