Determination of acoustic properties of paraffin oil mixed with activated coal nanoparticles or SPAN80 using only BAW time delay measurement

An important aspect of controlling the properties of liquids relates to their use in modern engines powered by composite materials. In this context, controlling the properties of industrial fluids containing micro- and nanoscale particles is essential. Understanding the temperature-dependent behavior of fluid density and elasticity is crucial for proper engine operation. Seven physical parameters of pure paraffin oil, paraffin oil with varying concentrations of activated coal nanoparticles or sorbitane monooleate (SPAN 80) were simultaneously determined using only BAW time delay measurement in the single experimental run. This technique relies on propagating LBAW through the test fluid and measuring the time delay and amplitude of these waves at different temperatures. By calculating temperature coefficients for velocity, density, time delay, and expansion using well-established formulas the physical properties of fluids under study were determined. The frequency of the LBAW used in the experiment was 13 MHz. The length of the liquid sample in the propagation direction of LBAW was ∼ 5 mm. The experiments were carried out within a temperature range of −20 °C to +90 °C. The volume of the test sample was around 1 milliliter. The comparison of the physical properties of different suspensions under these conditions allows us to demonstrate the dependence of the measured properties on the type and composition of the medium tested.