Common Terms in Liquid Ultrasonic Treatment

Six commonly used terms in liquid ultrasonic treatment: ultrasonic amplitude, power, frequency, power intensity, power density, and treatment rate. The use of ultrasonic treatment to manufacture nano lotion, grind drug crystals, degas, extract vegetable oil, manufacture biofuels, disperse pigments, destroy cells and enhance chemical processes requires familiarity with several general terms.

The efficiency of an ultrasonic processor is directly related to the intensity, uniformity, and magnitude of the cavitation field generated in the liquid. At present, it can be said that the main goal of tracking ultrasonic amplitude, power, frequency, power intensity, and power density is to ensure the optimal cavitation field distribution for a given task, thereby achieving the highest processing rate target product quality.

Ultrasonic Amplitude

Common units: micrometers or micrometers (µ m).

 

The ultrasonic tool head is a component that transmits ultrasonic vibrations to the liquid being treated with ultrasound and is responsible for generating cavitation. The amplitude of the tool head vibration surface is defined as the distance between the positions of the tool head in fully extended and fully contracted states, measured in micrometers (µ m). The amplitude can be adjusted from the control panel of the generator, and each horn has a specific maximum amplitude. The amplitude is set to a specific level in%, which corresponds to values in micrometers that can be identified using the calibration certificate of the tool head. Once the amplitude is set, it will remain at the same level throughout the entire process, regardless of all other conditions (such as the car's cruise control, which keeps the speed at a predetermined level).

 

The amplitude and intensity of cavitation are directly related. If you operate under low amplitude settings, the ultrasound treatment and related effects will be 'weak', while if you operate under high amplitude settings, the ultrasound treatment and related effects will be 'strong'.

 

Power : 

 

Common units: watts (W) or kilowatts (kW).

 

Power is a measure of the energy per unit time transmitted from the generator to the ultrasonic treatment liquid. It is measured in watts (W) or kilowatts (KW) and displayed in real-time on the screen of the generator. Power cannot be directly set as it is the result of multiple parameters, including amplitude, liquid viscosity, and pressure in the reaction chamber (for flow configuration) or tool head immersion depth (for batch configuration).

 

The generator automatically adjusts its power based on principles similar to those used in car cruise control. When going uphill, the engine power output will automatically increase to maintain a constant speed (in our example, amplitude). If the power required for ultrasonic treatment exceeds the power that the generator can provide, an overload error will be reported and ultrasonic output will be disabled.

 

Frequency:

Unit: Hertz (Hz) or Kilohertz (kHz).

The frequency measured in Hertz is the number of occurrences of repeated events per second.

 

 

The operating frequency of most high-power ultrasonic liquid processors is about 20kHz, which means their tool heads complete 20000 vibration cycles per second. Most complex processors are capable of automatically adjusting the frequency within the 19-21 kHz window based on the natural (resonant) frequency of the tool head. The tool head is a "resonant" device that operates only on "resonance", just like the strings of a guitar. The resonant frequency of the tool head is tracked and automatically adjusted by the generator during operation to compensate for any changes caused by temperature fluctuations. In some models, real-time frequency information is displayed on the generator screen.

 

Power Density:

Common units: watts per cubic centimeter (W/cm ^ 3) or kilowatts per liter (kW/L).

Power density is the amount of power transmitted per unit volume of ultrasound treated liquid. For constant volume modes, such as batch mode (e.g. liquid in a beaker) and circulation mode, power intensity and power density are directly related and can be used to represent cavitation intensity and the effectiveness of ultrasonic treatment. However, for one-way flow arrangements, the total volume of liquid passing through the cavitation zone during processing must be considered. In this mode, the power density is inversely proportional to the flow rate of the processed liquid through the reaction chamber and the total processing time.

 

Processing Speed:

Common units: milliliters per minute (ml/min), liters per minute [L/min], or cubic meters per hour (m ^ 3/h).

How many products can be produced per unit time using a given ultrasonic processor for processing speed. Maximizing processing speed while maintaining the required product quality is usually the main objective of optimizing the above parameters. After the optimization is completed, a curve similar to the example here is obtained (for the production of translucent nano lotion), where the product quality (in this case, the average droplet size) is related to the treatment rate, allowing final setting decisions. If higher processing speed is required for the same product quality, the process series can be expanded by switching to a larger processor (while ensuring that no optimization parameters are changed) or by using multiple processors in parallel or in parallel.