Where the inner diameter of the tube is very thin called "capillary tube". Usually refers to the inner diameter is equal to or less than 1 millimeter of the tube, because the diameter of the tube is as thin as a hair so called capillary tube. It is currently used in medicine and building materials.
Examples
Mercury thermometer, fountain pen tip slits, towels and ink blotting paper fibers between the gaps in the soil structure of the fine gaps, as well as plants, roots, stems, leaves, veins, etc., can be considered as capillary. Capillary electrochromatography is a new micro-separation analytical technique developed to integrate the advantages of capillary electrophoresis and micro-diameter column liquid chromatography, and to achieve its superior separation capability for samples with trace amounts of complex biological and chemical systems by applying a DC high-voltage electric field to both ends of the micro-diameter column column filled with micro-fine particles of liquid chromatographic packing.
Fine tube air conditioning: capillary network simulating leaf veins and human capillary mechanism, by the outer diameter of 3.5-5.0mm (wall thickness of 0.9mm or so) of the capillary tube and the outer diameter of 20mm (wall thickness of 2mm or 2.3mm) of the main trunk of the supply and return pipe constitutes the pipe network. Insulation layer, heat dissipation layer, and capillary network combined use, composite into a capillary network heat exchanger, greatly improving the capillary network of a single structure of the heat dissipation capacity and use of the purpose, to protect the capillary tube wall from damage. Plane radiation air-conditioning system of capillary network generally adopts a small cycle of large systems, and the use of special solutions as a medium, can avoid system blockage, easy to control. In order to achieve higher comfort requirements and avoid condensation, the room should also be equipped with humidity control and fresh air system. Capillary network production and application technology has previously been highly monopolized by German enterprises, Beijing Pulaifu Environmental Technology Co., Ltd. has broken the monopoly of foreign enterprises, research and development and production of domestic capillary network heat exchanger, applied for a number of invention patents and utility model patents, and has entered the mass production stage.
May 2007, the product in the China Academy of Building Research Air Conditioning (National Air Conditioning Equipment Quality Supervision and Inspection Center) for testing. To a node of the test as an example, the results are as follows:
1, in the experimental pressure of 1.5Mpa, no leakage;
2, in the water supply temperature of 45 ℃, the return temperature of 40 ℃, the base temperature of 20 ℃, △ T = 22.5 ℃, converted to samples of the unit area of the heat dissipation of Qdr = 240.88W/m2;
3, in the water supply temperature 15 ℃, return water temperature of 20 ℃, the base temperature of 26 ℃, △ T8.5 ℃, folding sample unit area cooling capacity Qdl = 122.84W/m2.
Tubing use
Capillary tube is generally used in small Freon refrigeration units of less than 20kW. The capillary tube is made of copper tube
Capillary tube
Composed of 1~6m in length and 0.5~2mm in inner diameter, the various combinations of length and diameter can make it meet the requirements of different working conditions and refrigerant devices with different cooling capacity, but the capillary tube can not be changed according to the load change after it has been selected and installed, and the design working conditions are very important and representative, so it is important to select the design working conditions that are representative and representative. In order to make the refrigeration unit operate efficiently most of the time, it is very important to select representative design conditions. [1]?
Capillary phenomenon
Edit
Definition: When an object containing a fine gap is in contact with a liquid, the liquid rises or penetrates along the gap in the case of wetting, and falls along the gap in the case of non-wetting. In the case of wetting, the finer the gap, the higher the liquid rises. It means that the liquid rises upward on the inside of a fine tubular object because of cohesion as well as differences in adhesion, overcoming the force of gravity.
Introduction
Capillary phenomenon (also known as capillary action) is the phenomenon in which a liquid rises or falls on the inside of a fine tubular object because of differences in cohesion as well as adhesion, overcoming the force of gravity.
Objects containing fine pores are in contact with a liquid so that that liquid rises or
capillary effect
falls along the pores. When the adhesion between the liquid and the solid (tube wall) is greater than the cohesion of the liquid itself, the capillary phenomenon (rise) occurs; conversely, when the adhesion between the liquid and the solid (tube wall) is less than the cohesion of the liquid itself, the capillary phenomenon (fall) occurs. This phenomenon is caused by the concave or convex shape of the liquid surface when the liquid is in a vertical tube, as well as by the ability of porous objects to absorb liquids. Capillary action occurs because of the viscous nature of water - the property of water molecules to stick to each other and to other objects, which can be glass, cloth, organ tissue or soil. Mercury, on the other hand, undergoes capillarity (falling) because of the extreme cohesion between its atoms.
The finer the capillary the less pronounced is the effect of air pressure on the absorption of water, so the finer the capillary the greater the degree of absorption of water perpendicular to the surface of the water.? [2]?
Influencing factors
The absorbency of the paper itself, the size and shape of the paper and the height of the water all affect the capillary phenomenon and produce many different results. And the temperature of the water will also affect the capillary phenomenon. The higher the temperature of the water, the faster the water rises, and vice versa. Therefore, the properties of the liquid itself are the main reason for capillary phenomena. Moreover, the increase in water temperature produces a large amount of water vapor, and therefore, water vapor also accelerates the capillary phenomenon. In addition when the cohesion of the liquid molecules is less than the attraction between them and the paper (or other substances) will also produce capillary phenomena (rise). Different liquids or paper, the capillary phenomenon will have the degree of difference. For example, mercury undergoes capillarity (falling) because of the strong cohesion between its atoms.? [2]?
Common examples
Water absorbed by plant roots can rise via the vascular bundles within the stem.
Plants absorb water
Submerge a paper towel in a cup of water and the water climbs up the paper towel until it is unable to overcome the Earth's gravity (gravity). Because water is viscous, when the water in your cup splashes onto your desktop, it doesn't run onto the floor, but forms a small, curved spot of water on the desktop.
Production Applications
While capillary action is extremely helpful for water absorption in plants, the capillary phenomenon can also have a negative impact in agricultural production. Soil is full of capillaries, and water from the ground often rises to the surface along these capillaries. If you want to conserve moisture underground, you should hoe the soil above ground to break up the capillaries at the soil's surface to minimize water evaporation.
When a house is built, the capillaries in a solid foundation are so numerous and fine that they draw moisture up from the soil, making the room damp. Laying linoleum on top of the foundation when building a house is to prevent moisture caused by the capillary phenomenon.? [2]?
Capillary electrophoresis
Editorial
Capillary electrophoresis (CE), also known as high performance capillary electrophoresis (HPCE), is a class of electrophoresis in which capillaries are used as the separation channel and high voltage DC fields are used as the separation channel. HPCE is a new type of liquid-phase separation technology that uses capillary as the separation channel and high voltage direct current electric field as the driving force. Capillary electrophoresis actually contains electrophoresis, chromatography and its cross content, which enables analytical chemistry to enter the nanoliter level from the microliter level, and makes single-cell analysis and even single-molecule analysis possible. The separation and analysis of biological macromolecules such as proteins, which has long been a problem for us, has thus taken a new turn.
Capillary electrophoresis is usually performed using flexible (polyimide) coated fused silica tubes with an inner diameter of 25-100 μm. Standard capillary tubes have an outer diameter of 375 μm, and some tubes have an outer diameter of 160 μm. The characteristics of capillary tubes are: small volume (a 100 cm × 75 μm tube has a volume of only 4.4 μL); large side/cross-sectional area ratio, which results in fast heat dissipation and can withstand high electric fields (100-1,000 V/cm); the ability to use free solution, gel, etc. as a support medium; and the ability to produce a plane-shape electroosmotic flow in a solution medium. shaped electroosmotic flow under solution medium.
The advantages of capillary electrophoresis are as follows:
(1) the number of high-efficiency plates is 105-106 plates/m, and the number of plates can be more than 107 plates/m when CGE is used in capillary electrophoresis chromatograms;
(2) the separation can be completed quickly within ten minutes;
(3) the sample volume required for microinjection is nL;
(4) the sample volume is nL;
(5) the sample volume is nL;
(6) the sample volume is nL; and the sample volume is nL.
(4) Multi-mode can be selected according to the needs of different separation modes and only one instrument is required;
(5) Economical experiments consume only a few milliliters of buffer solution, the maintenance cost is very low;
(6) Automatic CE is the current high degree of automation of the separation method.
The disadvantages of capillary electrophoresis are:
(1) poor preparative capacity due to small injection volume;
(2) small diameter of the capillary makes the optical path too short, and the sensitivity is lower when using some detection methods (e.g., UV absorption spectrometry);
(3) electroosmosis can vary depending on the composition of the sample, which in turn affects the separation reproducibility.
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