“Heat Tube Technology” -The working principle of thermal pipe


“Heat Tube Technology” -The working principle of thermal pipe

The basic working principle of the heat pipe is shown in the figure below.

Thermal pipe work principle diagram

The typical heat pipe consists of tube shell, suction liquid core, and end cover, and pump into the tube into the negative pressure of 0.00013 ~ 0.13Pa. Seal. One end of the tube is the evaporation section (heating section), and the other end is the condensed section (cooling section). According to the application needs, the thermal insulation section can be arranged in the middle of the two sections.

When one end of the heat pipe is heated, the liquid evaporation and vaporization in the hair core, the steam flows to the other end to the other end, and the heat is condensed into a liquid. With such a cycle, the heat was passed from one end of the thermal tube to the other end.

In the process of achieving this heat transfer, the thermal pipe contains the following six main processes of interrelated associations:

(1) The heat source is transmitted from the thermal source through the thermal pipe wall and the liquid core full of working liquid to the liquid stereotype interface;

(2) The liquid evaporates on the liquid and vapor division interface in the evaporation section;

(3) The steam in the steam cavity flows from the evaporation section to the condensed section;

(4) Steam condense on the steam solution interface in the condensation section;

(5) The calorie is passed to the cold source from the fluid split interface through the fluid core, liquid and tube wall;

(6) Due to the capsule in the absorbent core, the liquid after condensed returns to the evaporation section.

According to the working principle of the thermal pipe, the thermal pipe technology can be divided into the following parts.

(1) Temperature flattening

The temperature is also called the average temperature technology, that is, using the temperature of the thermal tube itself, the temperature field exhibition with uneven temperature is flattened into a uniform temperature field.

There is a cylindrical body with an uneven temperature field, which has a large temperature difference between the positive and negative sides of the cylindrical body, but if it is trying to arrange a certain amount of ring heating tube on the surface of the cylindrical body, the surface temperature of the cylindrical body will become very Small.

Another example is that in the chemical industry, it is often encountered in the chemical reactor’s unequal temperature problems, especially the temperature of the fixed bed catalytic reactor will affect the yield and quality of chemical products.

If we control the chemical reaction thermal equilibrium with heat pipes, we may obtain a more uniform temperature field.

The average temperature technology has important applications in spacecraft and electronic equipment instrument panels.

(2) Huiyuan separation

The so -called Huiyuan separation refers to the use of heat pipes to separate heat sources and heat exchange (cold source) in two places for heat exchange. This technology is of great significance in the heat exchange of continuous production.

Generally, the heat exchanges of the wall. At this time, if there is a small leak on the tube wall, the hot and cold fluids will immediately mix each other, forcing production to park. However, the use of heat tube heat exchanges, the two fluids of the source and sinks will no longer be mixed.

(3) Change the density of heat flow

The heat pipe can input heat in a smaller heating area, and the heat outputs heat with a large cooling area. On the contrary, it can also input heat in a larger heating area and output heat with a smaller cooling area. In this way, the heat flow on the unit of heating and cooling heat transfer can change.

The heat flow density transformation has an important application in engineering, such as controlling the temperature of the tube wall to avoid dew point corrosion.

(4) Thermal control (variable heat guide)

The variable heat conductor is a thermal tube that can be changed by thermal resistance, which can be used for temperature control. The graph is an inflatable variable heat conductor, and the condensation section of the heat pipe has a certain amount of non -condensed gas. When the thermal pipe is working, there are two areas in the heat pipe ① and ②, and ① are the saturated steam zone of the working liquid. Costuring gas zone.


The interface position of the two districts can be changed. When the temperature of the heat source of the evaporative section is higher than the rated value, the input heat will increase, the intraopea saturated steam pressure increases, the non -condensed gas is compressed, the interface is facing the right to the right to the right. Movement, the heat transfer area of ​​the condensate section increases, and the heat output also increases. The pressure of the intra naphtia steam decreases, and the interface position position is left to the left until the balance is reached.

When the temperature of the heat source is lower than the rated value, the heat input of the evaporation segment decreases, the intraoperative saturation steam pressure decreases, the non -condensed gas swells, the interface is moved to the left, the heat transfer area of ​​the condensed section is reduced, the heat output is reduced, and the inside of the tube will be reduced. Inside the tube The saturated steam pressure rises, and the interface is shifted to the right to maintain a balance when reaching the rated value.

Therefore, the heat input increases, the heat output also increases, the heat input decreases, and the heat output decreases. This can keep the working temperature of the thermal pipe unchanged.

Project variable thermal guidance technology can be used to control the temperature of heat sources or heat exchange.

(5) One -way guide thermal (thermal diode)

Using the principle of heat transfer of gravity heat pipes, the heat tube can be regarded as one -way thermal conductivity, as shown in the figure.

Heat diode working principle

In the picture (a) is below the condensation section, the heat pipe can work normally; (b) is below the evaporation section, while the thermal tube cannot work.

The principle of thermal diode has an important application in the solar and land permanent freezing project.

(6) The heat transfer of the rotating element (rotating thermal tube)

Generally, the heat pipe is a static heat transfer element, and the rotating thermal tube is an element of heat transfer in the rotation movement. The principle is that the liquid in the heat pipe relies on the centrifugal force in the rotation to return from the condensation section to the evaporation section, or the liquid position is poor. Gravity generated.

Rotating thermal pipe work principle diagram

The rotating thermal tube can be used as a heat transfer element for high -speed rotating shafts in the project, such as the cooling equipment such as motor shaft, high -speed drill bit, and turning equipment such as plastic fiber and plastic film processing.

(7) Micro heat pipe technology

With the rapid development of electronics and electrical engineering, the heat dissipation of micro -electronic devices and components has become an important problem. The research of micro -heat pipes is developed to this requirement.

The concept of miniature heat pipe is different from the concept of conventional thermal tube. Its capacity is not produced by the liquid core but provided by the bending moon surface of the liquid seam around the steam channel.

The cross -section of the steam channel has various shapes, including triangles, rectangles, squares, trapezoidal, etc. There is no absorbent core in the tube.

Micro heat pipes have important applications in the heat dissipation of semiconductor chips, integrated circuit boards, and laptop CPUs.

(8) High -temperature thermal pipe technology

Under the heat exchange conditions with a temperature of more than 700 ° C, there will be many difficulties using ordinary heat exchangers, such as non -temperature difference stress, high temperature creeping material, and high temperature corrosion.

High -temperature heat pipes can bring great convenience, such as small temperature difference stress, simple structure, not vulnerable to high temperature damage, single thermal tube damage does not affect the overall performance of the equipment.

The working liquid of high -temperature heat pipes is liquid metal (sodium, potassium, lithium, 铯, etc.). It is characterized by low pressure of saturated steam. Therefore, under high temperature conditions, the heat pipe of the work only withstand high temperature and does not withstand high pressure in the tube.

High -temperature thermal pipes have important uses in nuclear engineering, solar power stations, Sterling engines, high -temperature thermal air furnaces, high -temperature slag mouths, and red thermal body heating.

Product Recommendation: Chemical Reactor