An electromagnetic sensor and method for extraction of transient vapor fraction in dynamic systems.

The capture of transient steam quality provides valuable insight into the operational conditions needed for process control and design of saturated steam systems. Acquisition of accurate fluid phase or composition before the system reaches steady-state operation poses technical challenges preventing the use of most existing commercial and experimental methods. An electromagnetic sensing method in the microwave frequency band enables this capture of compositional data at over 200 samples per second. The planar microwave sensing element allows for the in-situ measurement of a two species fluid to be taken, without the usual requirement of laminar flow found in many density-based approaches. Harsh environmental conditions presented in typical saturated steam processes dictated special design considerations to enable survivability of the sensor. Effective medium models for both pure and polluted saturated steam were implemented to compensate for contamination of the working fluid to provide estimated bounds for a mass fraction of the liquid to vapor content. The addition of pressure and temperature data enables an estimate of enthalpy made for saturated fluid cases and applications.