System and method for detecting the presence of bubbles in aqueous solutions
A system for detecting the presence of bubbles in a solution includes an ultrasonic receiver, receiving a pair of signals having different frequencies after passage through the solution, and a computing unit. The computing unit computes a signal value for each of the signals, the signal value representing a defined signal property, compares the signal values for the signals with each other and/or each with a predefined reference value, and computes a deviation of the signal values from each other and/or between the signal values and the predefined reference value. The computing unit generates a bubble confirmation signal that confirms the presence of bubbles in the solution if the deviation is greater than a predefined threshold value.
1. A system for detecting the presence of bubbles in a solution, comprising:
an ultrasonic receiver receiving a pair of signals having different frequencies after passage through the solution; and
a computing unit computing a signal value for each of the signals, the signal value representing a defined signal property, comparing the signal values for the signals with each other and/or each with a predefined reference value, computing a deviation of the signal values from each other and/or between the signal values and the predefined reference value, and generating a bubble confirmation signal that confirms the presence of bubbles in the solution if the deviation is greater than a predefined threshold value.
2. The system of claim 1 , wherein the solution is an aqueous solution.
3. The system of claim 2 , wherein the aqueous solution is a urea solution.
4. The system of claim 1 , further comprising an ultrasonic transmitter generating the pair of signals.
5. The system of claim 4 , further comprising an ultrasonic transducer in which the ultrasonic transmitter and the ultrasonic receiver are combined.
6. The system of claim 1 , further comprising a reflector spaced apart from and arranged opposite to the ultrasonic receiver, the reflector reflecting the pair of signals to the ultrasonic receiver.
7. The system of claim 1 , wherein the signal value is at least one of a signal amplitude, a time of flight, and a frequency at which a frequency spectrum has a maximum.
8. A method for detecting the presence of bubbles in a solution, comprising:
receiving a pair of ultrasonic signals having different frequencies after passage through the solution;
computing a signal value for each of the ultrasonic signals, the signal value representing a defined signal property;
comparing the signal values for the ultrasonic signals with each other and/or each with a predefined reference value;
computing a deviation of the signal values from each other and/or between the signal values and the predefined reference value; and
generating a bubble confirmation signal that confirms the presence of bubbles in the solution if the deviation is greater than a predefined threshold value.
9. The method of claim 8 , wherein the ultrasonic signals having different frequencies are emitted into the solution prior to receiving the ultrasonic signals.
10. The method of claim 8 , wherein a time of flight for each of the ultrasonic signals is computed and used as the signal value.
11. The method of claim 10 , wherein an envelope is calculated for each of the ultrasonic signals and used for computing the time of flight.
12. The method of claim 8 , wherein an amplitude of each of the ultrasonic signals is computed and used as the signal value.
13. The method of claim 12 , wherein the amplitude of each of the ultrasonic signals is referenced using a predefined reference value for each of the ultrasonic signals before the comparing step.
14. The method of claim 8 , wherein a frequency spectrum is computed for each of the ultrasonic signals.
15. The method of claim 14 , wherein a frequency at which the frequency spectrum has a maximum is used as the signal value.
16. The method of claim 15 , wherein a fast Fourier transformation is used for computing the frequency spectrum.
17. A urea sensor system for measuring a property of a urea solution in a volume, comprising:
a system including an ultrasonic receiver receiving a pair of signals having different frequencies after passage through the urea solution and a computing unit computing a signal value for each of the signals, the signal value representing a defined signal property, comparing the signal values for the signals with each other and/or each with a predefined reference value, computing a deviation of the signal values from each other and/or between the signal values and the predefined reference value, and generating a bubble confirmation signal that confirms the presence of bubbles in the urea solution if the deviation is greater than a predefined threshold value.
18. The urea sensor system of claim 17 , wherein the urea sensor system is used to measure a speed of sound in the urea solution.