Technicality

  • What is mixing?
  • Super-Mix Series
  • Calorimeter

What is mixising

There are probably only a few people who can readily understand the meaning of mixing. But it is no exaggeration to say that mixing is in some way involved in everything we see and touch. A mixing machine of course refers to a machine used for mixing. Or more accurately, it may be easier for you to understand if we call it a mixer, or agitator, as it is called elsewhere.

Mixing of coffee
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Let us begin our explanation of mixing by describing a simple and familiar activity.

What would you do after adding milk and sugar to your daily cup of coffee or after pouring water into a tank tub to reduce the temperature of water that is too hot? You always stir your coffee or hot water in the tub, don't you? Yes, this very mixing action of adjusting the taste of coffee or equalizing the temperature of hot water is what we call mixing.

Mixing refers to achieving a specific purpose by this action. We have expressed the meaning of mixing using only a few words. But the reasons for mixing vary greatly. There are countless reasons why substances are mixed and mixing actions vary to a great extent. These actions become more complex as they vary from small instances of mixing, for example, in a cup of coffee, to mixing that takes place in a large tank of several square meters in size, or in a square tank, a round tank, a long and thin tank, mixing of water and other substances of low viscosity, or sticky substances such as starch syrup, mixing of different liquids, mixing of solids and liquids, gaseous bodies and liquids, and the mixing of many elements combined. Accordingly, mixing may be regarded as the "behind the scene" player that supports our daily lives by helping us make all kind of things.

Now, we will give you a more detailed explanation about what is happening inside a tank.
To effect mixing of substances in a tank, we need two types of mixing actions, namely convection and diffusion. Convection is particularly important for mixing things. Mixing plays a role of positioning elements uniformly in a space by efficiently dividing or expanding different substances in the tank. On the other hand, diffusion refers to an aspect where various elements mix spontaneously through molecular motion. Compared with convection, things can be mixed thoroughly to a finer level by diffusion since it takes place at the molecular level. But diffusion takes longer before a completely mixed state is reached.

Now, we will use a pattern diagram to look at convective mixing, which is an important part of the mixing process.

1

State (1) shows two elements, A and B existing in separation. Supposing that the abundance ratio for the two elements is 1:1, concentration of element B in the total will be 1/2.

2

State (2) shows the two elements in a finely segmented state.

3

State (3) shows the two elements repositioned at random.Contact areas for mutual elements increase during the advanced state of mixing. It is still not complete, however, and the local concentration of element B in a portion enclosed by dotted lines reads 1/4 and 5/9 respectively. Mixing advances as the segmentation in (2) and repositioning in (3) are repeated.

To segment both elements to a finer level, deformation and relative displacement (elongation, shearing, division, superposition, rotation, dispersion, etc.) as shown in the following (4) to (7) will be necessary.

4

State (4) is the aforementioned State (1) extended to the left and right and made finer. This process can increase the contact areas for both elements.

5

Superposing both elements in State (4) by rotation produces State (5), State (6) by folding back, or State (7) by shearing and overlaying. As before, the local concentration of element B in a portion enclosed by dotted lines reads 2/3 and 2/4 respectively.

6

7

Mixing advances as the process (4) to (7) is repeated.
Now, let us apply this pattern diagram to actual phenomena.

Mixing liquids fluidizes solid substances in the liquid, causing them to disperse evenly. In other words, the key to dissolving solids in liquid lies in how to fluidize them. Mixing ingredients for preparing soup is the former while dissolving salt and miso (bean curd) in water falls under the dispersion and repositioning of (1) to (3).

Agitating solids and fluids
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Liquids tend to mix spontaneously due to their coming in contact with each other. Agitating them promotes mixing by expanding their areas of contact through forcible elongation and division. Mixing coffee and milk or hot water and cold water is an example, which falls under the shearing, elongation and superposition of (4) to (7).

Agitating fluids of different sort
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Water and oil never mix mutually. Only by agitating them is it possible to finely disperse droplets of oil in the water. It may be a little difficult to understand, but shaking a bottle of dressing before using it is an example of this action.

Agitating water and oil
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To agitate the contents of a tank, we have to start a flow in the tank. With an actual mixing device, a motor-driven impeller rotates to create the flow.

There are various impellers designed in different shapes for a variety of applications. Some impellers has strong shearing (destructive) force while others have weaker force. Some impellers create fast flows while others create slow flows, and characteristics vary according to the form of the flow. The basis for everything lies in this flow. By utilizing the flow skillfully, we can achieve various aims of mixing different liquids, dissolving solids or gaseous bodies into liquid, equalizing the temperature of substances, or dispersing substances without destroying them.

Satake provides you with technology to meet all your mixing requirements through the concentration of our efforts on the development of better impellers.

Aspect of the flow
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