A waste heat recovery system is disclosed. The waste heat recovery system may include a turbine expander. The turbine expander may include a turbine blade rotatably coupled to a shaft and the shaft may be rotatably engaged with a nozzle ring. The nozzle ring may include a de Laval-nozzle. The waste heat recovery system may additionally include a pressure sensor. The pressure sensor may be located fluidly upstream of the de Laval-nozzle and fluidly downstream of an evaporator. The pressure sensor may be configured to measure pressure of a working fluid and transmit a working fluid pressure signal. Further, the waste heat recovery system may include an electronic controller. The electronic controller may be configured to receive the working fluid pressure signal and transmit a working fluid flowrate adjustment signal in response to the working fluid pressure signal.