Sensorless condenser regulation for power optimization for ORC systems

A method for regulating a condenser in a thermal cycle apparatus, wherein the thermal cycle apparatus comprises a feed pump for conveying liquid working medium with an increase in pressure to an evaporator, the evaporator for evaporating the working medium with a supply of heat, an expansion machine for generating mechanical energy by expansion of the evaporated working medium, a generator for at least partially converting the mechanical energy into electrical energy, and the condenser for condensing the expanded working medium, and wherein the method comprises the following steps:

• determining a rotational speed of the generator or of the expansion machine;
• determining, without the use of a temperature sensor, a temperature of cooling air supplied from the condenser;
• determining from the determined generator or expansion machine rotational speed and the determined cooling air temperature, a condensation setpoint pressure at which a net electrical power of the thermal cycle apparatus is at a maximum;
• and
• controlling or regulating a condensation pressure, with the condensation setpoint pressure as a target value by adjusting a condenser fan rotational speed,
• wherein determining the temperature of cooling air supplied from the condenser further comprises one of (i) calculating the temperature of cooling air from the determined rotational speed of the generator or of the expansion machine, a determined rotational speed of the condenser fan and a determined condensation pressure, or (ii) sampling the temperature of cooling air from a predetermined table dependent upon the determined rotational speed of the generator or of the expansion machine, a determined rotational speed of the condenser fan and a determined condensation pressure.