Virtual Superheat Measurement Sensor for Refrigeration Cycle

A method for determining superheat for an air-conditioning system or a heat pump system using a virtual superheat measurement system. The method includes a obtaining a compressor efficiency; acquiring concurrent noninvasive measurements of a suction, a discharge, and a condensing temperature; determining a discharge pressure as a saturated pressure corresponding to the condensing temperature; determining a first discharge enthalpy and a discharge entropy as functions of the discharge temperature and the calculated discharge pressure; for all possible values of suction pressure: guessing the suction pressure; determining a suction enthalpy and a suction entropy as functions of guessed suction pressure and suction temperature; determining a second discharge enthalpy as a function of the discharge pressure and the calculated suction entropy; and determining a second compressor efficiency as the difference between the second discharge enthalpy and the suction enthalpy divided by the difference between the first discharge enthalpy and the suction enthalpy.