To mitigate the potential significant impact on our society due to the continued reliance on high-cost diesel hydrocarbon fuel and the implementation of increasingly strict emission controls, an apparatus is disclosed which provides the means for extracting additional heat from an internal combustion engine while providing the cooling needed to meet stricter emissions standards. The present disclosure describes an apparatus operating on a Rankine cycle for recovering waste heat energy from an internal combustion engine, the apparatus including a closed loop for a working fluid with a single shared low pressure condenser serving a pair of independent high pressure circuits each containing zero or more controlled or passive fluid splitters and mixers, one or more pressure pumps, one or more heat exchangers, and one or more expanders, and the means for controlling said apparatus.