Development of Viscosity Real-Time Measurement System Based on Capillary Method

Based on the horizontal capillary method, a real-time measurement system of the fluid viscosity is developed in this work. The system includes the flow process adjustment module and the viscosity online detection module, and the temperature measurement range is 293.15–333.15 K. The system is calibrated using alcohols and hydrocarbons with known viscosity as reference substances. The measurement model of the system is established by the relationship between viscosity and differential pressure, and it is applicable for viscosity measurement in the range of 0.23–7.42 mPa
$\cdot \text{s}$
. The accuracy of the system is verified by measuring the viscosities of three kinds of fluids (including alcohol, hydrocarbon, and ester). Furthermore, the expanded uncertainty is obtained within 4.32% by evaluating all the impact factors for the viscosity measurement. For the convenience of application, a calculation method of viscosity is proposed based on an improved Cano-Gómez (ICG) model. The average absolute relative deviations (AARDs) of the ICG model, the original CG (OCG) model, and the rough hard sphere (RHS) model are 0.96%, 0.98%, and 0.99%, respectively.