I am currently working on turbine design for small scale ORC system to produce power from low-enthalpy heat source. In ORC, turbine inlet pressure and flow rate are controlled by pump, and turbine inlet temperature is determined by evaporator when the flow rate of refrigerant and enthalpy of heat source are constant. During turbine operation, I am curious about how to control turbine outlet pressure (condenser inlet pressure) and rotational speed. Is the outlet pressure controlled by turbine, condenser or buffer tank? How to change turbine speed?