As environmental regulations continue to improve the requirements of major engine manufacturers to optimise the SCR system (Selective Catalytic Reduction Technology selective catalytic reduction technology) to meet the requirements of the environmental protection department.SCR programme in the diesel exhaust emissions treatment system has obvious advantages, and automotive urea is the necessary additives for the SCR programme Urea is an essential additive for the SCR programme.
Automotive urea is an organic compound consisting of carbon, nitrogen, oxygen and hydrogen. The urea solution used for aftertreatment is a high-purity solution containing 32.5% urea and 67.5% deionised water, which decomposes into ammonia (NH3) and water when heated to 160°C. The urea is used for the treatment of diesel exhaust emissions. Automotive urea plays a key role in vehicle power, fuel consumption and exhaust emissions. Urea quality sensors are installed in urea tanks to monitor the quality of urea in real time, and ultrasonic measurement is currently the more mature solution on the market.
How can ultrasonic sensors analyse the quality of urea?
The main principle: the use of ultrasound in different media propagation speed difference for urea identification and urea concentration detection. At a fixed distance, the flight time of ultrasonic waves varies in different media and for different urea concentrations.
Corresponding curves of propagation speed and temperature in different media (water, coolant, air, urea solution, etc.) are fitted to the corresponding functional equation, which shows that ultrasonic propagation speed is inconsistent in different media, and that the time of flight is inconsistent in a fixed distance to identify water and urea.
Corresponding curves were established for different urea concentrations and propagation speeds, and the corresponding functional equations were fitted. The graphs show that the ultrasonic waves propagate at inconsistent speeds in different concentrations of urea, and identify different concentrations of urea by different flight times within a fixed distance. An ultrasonic probe (transceiver) was utilised to send out acoustic pulses to a reflective baffle and then reflected back to the probe. The average Time of Flight (TOF) is calculated over a number of cycles and is almost constant at a fixed temperature and at a urea concentration of 32.5%.
Audiowell introduces the urea quality sensor HQ0084-000, which monitors the quality and concentration of urea by testing the time of flight in the medium (urea).
Features:
Good consistency
- High reliability
- Accuracy <1% (with matching circuit)
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