Ice fraction estimation for ice slurries through impedance measurements

A new approach to ice concentration measurement for ice slurries is proposed and investigated in this work. The technique is based on in-line measuring of the impedance of an ice slurry flow. An impedance sensor was designed and built to conduct experiments. The sensor measures the impedance of the ice slurry flow in a frequency domain ranging from 20 to 120 kHz. Using this broad range of measurements, multiple parameters are determined which are then linked to the ice concentration. Ethanol is utilized as freezing point depressant. The initial ethanol concentration was varied from 3 to 6 wt-% and ice fractions from 0 to 50 wt-% were used. The ice concentration was also determined using temperature, density and calorimetric measurement. These other techniques were used as a reference and compared to the proposed impedance measurement technique. The measurement accuracy was shown to be at odds with the accuracy of the other measuring techniques. Other advantages of the proposed measuring method are the possibility to perform the measurement in-line and the low cost of the sensor