Definition
Shear emulsification mixer is a type of laboratory equipment used for mixing, dispersing, and emulsifying processes. It exerts strong mechanical and hydraulic shear forces on the fluid material through the synergy between the rotor and the stator at high speed, so as to achieve the refinement, homogenization and emulsification of the material. The equipment has a wide range of application values in chemical, food, cosmetics and materials science.
Principle
The core working mechanism of the shear emulsifying mixer is based on the rotor-stator structure. The rotor rotates at high speed driven by a motor, drawing the material from the bottom of the container into the working chamber. In the narrow gap between the rotor and the stator, the material is subjected to strong shear, impact and turbulence, resulting in particles or droplets being broken into smaller sizes. At the same time, the material undergoes high-frequency circulation within the chamber, further promoting the uniformity of mixing. The whole process can be regarded as a combination of mechanical energy and hydraulic energy, and its shear rate is closely related to the rotor line speed, clearance size and other parameters.
Measurement and evaluation methods
The performance of a shear emulsifying mixer is usually indirectly evaluated by the characteristics of the treated material. Particle size distribution is a key measure of emulsification or dispersion and can be measured using a laser particle size analyzer. Changes in viscosity can be monitored by a rotary viscometer to assess changes in rheological properties. For emulsified systems, stability can be assessed by centrifugation acceleration experiments or by long-term standing observation of stratification. In addition, the temperature rise during the processing process needs to be monitored in real time using temperature sensors to avoid overheating affecting the material properties.
Influencing factors
The treatment effect of shear emulsifying mixer is affected by multiple factors. The rotor speed directly affects the shear strength, and usually the higher the speed, the smaller the dispersion particle size. The geometry and clearance size of the rotor and stator determine the characteristics of the shear flow field. The length of processing time should be optimized according to the initial state of the material and the target particle size. Physical properties such as viscosity, solids content and proportion of materials can also significantly affect energy transfer efficiency. In addition, the control of operating temperature is particularly important for the handling of heat-sensitive materials.
Applications
In the food industry, this equipment is used for the preparation of sauces, dairy products and the emulsification and homogenization of beverages. It is commonly used in the cosmetics sector to produce creams, lotions, and to achieve a delicate texture. The chemical industry uses it for nanomaterial dispersion, polymer blending, and dye grinding. In biotechnology, it can be used for cell disruption or media mixing. Sample preparation in environmental analysis sometimes involves the use of small shear emulsifiers.
Selection considerations
When selecting, the nature of the material being processed and the production requirements should be comprehensively considered. For high-viscosity materials, choose a model with sufficient torque and pay attention to heat transfer design. The throughput determines the matching of the working chamber volume with the motor power. Material compatibility is critical, especially for components that come into contact with corrosive or high-purity materials, stainless steel or special coatings should be used. The accuracy and functions of the control system, such as speed adjustment range, timing and temperature monitoring, can affect the repeatability of the operation. The easy-to-disassemble design and ease of cleaning are also important considerations in daily laboratory use.