What Information About High-Pressure Thermophysical Properties of Liquids Can Provide Low-Intensity Ultrasonic Waves

In many technological processes liquids are subjected to high pressures (up to 800 MPa), e.g., in high pressure preservation of liquid foodstuffs. Similarly., in modern fuel injection systems for diesel engines., biofuels are subjected to pressures up to 300 MPa. In such severe conditions., thermophysical properties of liquid change considerably. Conventional methods for measuring thermophysical properties of liquids completely fail at high pressure conditions. Hence, these methods are of no use in real industrial conditions, during on-line monitoring of industrial processes. Thus, there exist a strong demand for industrial grade measurements methods, which can be used to monitor on-line the actual parameters of liquids. A very promising solution is offered by ultrasonic techniques which are particularly suitable for measurements of thermophysical properties of liquids at high pressures. In addition, the ultrasonic methods (that use low-intensity ultrasonic waves)are totally non-destructive and can be fully automated in real time.