Dear Munshi,

Yes you can. There is a quartz crystal microbalance based method for measuring the viscosity and density of various liquids. You may check the following articles: Martin S. J., Frye G. C. and Wessendorf K. O. “Sensing liquid properties with thickness shear mode resonators”, Sens. and Act. A, Vol. 44, no. 3, 1994, pp. 209-218.; Doy N., McHale G. and Newton M. I. “Separate density and viscosity determination of room temperature ionic liquids using dual quartz crystal microbalances”, IEEE Sens. Conf., 2009, pp. 287-290.

Sincerely,

Karekin

Hi Munshi and Karekin

I have not read the above material but I am guessing that these are active methods that rely on a source that excites the fluid and response is measured as a transfer function and modal parameters are derived from the response? The examples I have seen for other applications used separate chambers for the measurements though I imagine that it should be possible to use also acoustic cross section modes and a live flow. 

I would like to draw your attention also to passive methods.

One can use piezocables and pulsation that is naturally generated by the flow. Resonance frequency, loss factors and similar can then be derived using so called Operational Modal Analysis. 

http://qringtech.com/2014/01/28/how-to-measure-pulsation/

http://qringtech.com/2017/05/20/slugging-pulsating-pressure-source-characteristic-measurement/

Sincerely

Claes

Dear Claes, 

       The quartz crystal microbalance (QCM) is a disk-shaped quartz crystal mounted between two electrodes (typically gold for liquid applications). The electrodes are used to excite a mechanical deformation in the crystal, due to the converse piezoelectric effect, and then generate an electric signal at the output due to the direct piezoelectric effect. In order to generate any signal, the device should be connected to an appropriate electronic interface (could be network analyzer or sensor oscillator with frequency counter), which provides continuous readings of the resonance frequency oscillations (these oscillations are inversely proportional to the QCM's thickness). Once a liquid is deposited on the QCM's surface, a resonance frequency shift occurs proportionally to the viscosity/density product of the liquid, as a result of wave propagation within the liquid and partial dissipation of the acoustic energy (the acoustic impedance mismatch between both media). So, the above mentioned articles demonstrate very intelligent way of separating the influence of viscosity and density of the liquid-of-interest on the sensor signal. 

       p.s. The waves generated by the QCM are of electromechanical origin, but since the wave velocity in the crystal approaches that of the sound in solids, researchers have started calling them "acoustic waves". 

Sincerely,

Karekin

Hi Karekin

Thanks for the system description. More or less, it is the kind of system I envisaged. Some use an exciter and a receiver, some combine exciter/receiver.

In my world, it is similar to impact or shaker testing for Experimental Modal Analysis.

For what it is worth, I believe that you can derive the same properties using also a passive approach with externally applied sensors using e.g. Operational Modal Analysis and piezocables.

There may be differences in observability that stem from system dimensions versus material characteristics, i.e. the disc you describe may operate at frequencies that better highlight some properties than would be possible when monitoring a large diameter process flow and, naturally, the situation may well be a reverse. Also, the passive approach would be more of a field approach while the method you describe seems more like a precision/lab method.

One can do fun things with piezochrystals. One guy I know used it to sort particles using acoustic streaming.

Sincerely

Claes

Dear Mr. Rasel,

Your best bet is to follow the literature that colleague Esmeryan fittingly suggested.

For the sake of completeness, additional reading should include two papers by Diethelm Johannsmann and coworkers, in which the advantages of nanoporous alumina are reported [1] for the determination of liquid density and viscosity. Furthermore, in [2] QCM and torsional resonators are jointly used for the determination of liquid viscosity and dielectric properties, as well as for the quantitation of viscoelastic effects.

Temperature regulation of the liquid phase is a prerequisite, which extends beyond the necessary adjustments in the experimental setup. AT-cut quartz constants ε22, e26, c66 and quartz density ρq are temperature dependent, hence their values need to be adjusted accordingly in the models suggested in the literature. Recent work [3] has shown that temperature adjustment of ε22, e26, c66 fully accounts for inherent physical and energy dissipation effects in commercial QCM sensors.

Regards,

Thanasis

[1] Goubaidoulline, I., Reuber, J., Merz, F., Johannsmann, D., "Simultaneous determination of density and viscosity of liquids based on quartz-crystal resonators covered with nanoporous alumina", J. Appl. Phys. 98 (2005) 014305 (4pp.)

[2] Johannsmann, D., Bucking, W., Bode, B., Petri, J., "Simple frequency-based sensing of viscosity and dielectric properties of a liquid using acoustic resonators", IEEE Trans. Ultrason. Ferroelectr. Freq. Contr. 57 (3) (2010) 677-683.

[3] Kakalis, A., Panayiotou, C., "The temperature effect of AT-cut input quartz parameters on QCM effective properties calculated with equivalent circuit models", J. Electroceram. (2017) in press.

Dear all

It seems we are discussing very different ways to derive similar properties.

Just to clarify.

A Quartz Crystal Microbalance (QCM) is a tiny device that operates at MHz, whereas I am discussing use of externally sensors on the actual process piping that can operate at Hz to kHz.

I looked the method up here

https://en.wikipedia.org/wiki/Quartz_crystal_microbalance

A bit like comparing a micrometer with a sledge.

A key difference between the ideas, as best I understand them, is that the QCM relies on molecules attaching to its surface while use of a pipe relies on acoustic waves propagating in the flow of the media flowing through the pipe.

Also, as the QCM operates with one side free, it is  easier there to detect density than it is using wave propagation.

The QCM was new for me though the signal identification part is old hat. For what it is worth. If there is any advantage in doing so, the identification of data can be improved using methods from Experimental Modal Analysis, e.g. to incorporate multiple modes of operation rather than single peaks/tones. Also, one can use forced excitation rather than decay measurements to improve signal to noise. 

That said, I do believe that similar properties can be identified using both approaches. As the time scale differs greatly, i.e. MHz versus Hz or kHz - my approach will likely have a lower precision or require longer time spans in detecting differences, simply as it has to operate with smaller shifts in frequency.

Then - again - sometimes, there is an advantage to operate at particular frequency ranges as viscosity/damping is not always a single number as it may very with differences in relaxation time, e.g. as is the case for viscoelastic materials.

https://en.wikipedia.org/wiki/Time%E2%80%93temperature_superposition

Now - Munshi - what is it that you refer to as acoustic sensors for your application?

Is it a device like the QCM or a direct measurement on the piping or in the flow for a production flow - both methods, or is it something else?

Sincerely

Claes

Hi Munshi,

Either ways presented by Karekin and Athanasios OR Claes can be used for the measurement of viscosity and density of fluid. What is the scope of your measurement? Industrial/academic research/fun project? What reliability would you expect for the measurement? If you are running a low budget project and you do not need a very high reliability, go for QCM. It is a piezo-sensor with a very simple measurement technique. See the articles suggested by Karekin and Athanasios. I want to point out that the QCM sensor is very sensible to not only the viscosity and density of the fluid but also on its other properties such as viscoelastic nature, hydrophobicity with the sensor electrode surface etc. Therefore, the accuracy is sometimes poor for say non-Newtonian liquids. If you need very high accuracy measurement go for the other option.

Dear Acharya,

     I disagree that the accuracy of the QCM approach is low. The quartz crystal microbalance is a sophisticated device that can measure and "catch" almost anything with a very high resolution and precision, but the operator has to be qualified enough to use it. Indeed, the QCM is sensitive to thermal drifts, as well as the value of the solid-liquid interfacial tension. However, if one knows how to operate with the device and eliminate all other effects, then, one will have a very versatile tool to perform high-quality research in almost any field e.g. biofouling assays, determination of anti-icing properties, measuring viscoelasticity of various membranes, etc. Also, most of the pragmatic ideas nowadays rely on the requirement for cost-efficiency. It is easy to work when you have high financial budget and far more difficult to doing research that can optimize the total amount of expenses. Last but not least, in years of global financial crisis most of the companies are trying to reduce the cost of their products. What better way of doing this when one is withdrawing conclusions for processes that can be monitor with an inexpensive equipment? 

Sincerely,

Karekin