Paper Title
Evaluation of Ultrasonic Propagation to Measure Concentrations of Urea Solution

Abstract
In order to convert the harmful exhaust gas emitted from diesel engine vehicles into harmless substances, it is necessary to add a catalyst reducing configured by urea and deionized water, and it is very important to monitor the urea concentration in real time to keep the high reaction efficiency. Therefore the aim of this study attempts to measure the urea concentration by self-made high-frequency ultrasonic transducers by using the echo method to measure the ultrasonic properties under different concentrations of urea solution, and find the correlations between concentration and propagation velocity / power attenuation coefficient. The results show that the concentration measurement using the high-frequency ultrasonic measurement system of this study can achieve a very high linear correlation between the propagation velocity and urea concentration, thus achieving high-resolution, high-accuracy concentration measurement requirements. Keywords - Urea solution, Concentration, Ultrasonic velocity, Power attenuation, Ultrasonic transducer