A waste heat recovery system includes a closed fluid circuit through which an organic motive fluid flows, and a heat exchanger for transferring heat from waste heat gases to the motive fluid. A first flashing unit flashes the motive fluid which exits the heat exchanger into a high pressure flashed vapor portion. Another flashing unit flashes liquid non-flashed motive fluid, producing a low pressure flashed vapor portion. A high pressure turbine module receives the high pressure flashed vapor portion to produce power, and a low pressure turbine module receives a combined flow of motive fluid vapor comprising the low pressure flashed vapor portion and discharge vapor from the high pressure turbine module whereby additional power is produced.