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Aluminum Heat Sink & Profile Manufacturing

address:No. 51 Luming Road Heavy River Management District - Qing Town Dongguan City

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Telephone:+86 13827205356

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Heat dissipation method and heat dissipation efficiency

time:2021-01-10 16:46 author:Heat sink design click:

Design different heat dissipation methods of heat sink
The way of heat dissipation refers to the main way of dissipating heat of the heat sink. In thermodynamics, heat dissipation is heat transfer, and there are three main ways of heat transfer: heat conduction, heat convection and heat radiation.
The heat dissipation efficiency of the heat sink is related to the thermal conductivity of the material, the heat capacity of the heat dissipation medium, and the effective heat dissipation area.

The material itself or when the material contacts the material, the transfer of energy is called heat conduction, which is the most common way of heat transfer. For example, the direct contact between the CPU heat sink base and the CPU to take away heat is heat conduction. Thermal convection refers to the heat transfer method by which a flowing fluid (gas or liquid) transfers the heat away. The "forced heat convection" cooling method in which the cooling fan drives the air flow is more common in the cooling system of the computer case. Thermal radiation refers to rely ray radiation heat transfer, the most common is the daily solar radiation. The three cooling methods are not isolated, in the daily heat transfer, the three cooling methods are simultaneous, joint works.

In fact, any type of heat sink basically uses the above three heat transfer methods at the same time, but the focus is different. For example, a common CPU heat sink, the CPU heat sink is in direct contact with the CPU surface, and the heat on the CPU surface is transferred to the CPU heat sink through thermal conduction; The cooling fan generates airflow to take away the heat from the surface of the CPU heat sink through thermal convection; The air flow in the chassis also takes away the heat of the air around the CPU heat sink through thermal convection until it reaches the outside of the chassis; At the same time, all parts with high temperature will radiate heat to parts with low surrounding temperature.

According to the way of removing heat from the heat sink, the heat sink can be divided into active heat dissipation and passive heat dissipation. The air-cooled radiator is common in the former, and the heat sink is common in the latter. The heat dissipation methods are further subdivided into air cooling, heat pipe, liquid cooling, semiconductor refrigeration and compressor refrigeration, etc.

Heat conduction method of heat sink
Air-cooled heat dissipation is the most common, and very simple, is to use a fan to take away the heat absorbed by the radiator. It has the advantages of relatively low price and simple installation, but it is highly dependent on the environment. For example, the heat dissipation performance will be greatly affected when the temperature rises and overclocking.

The heat pipe is a heat transfer element with extremely high thermal conductivity. It transfers heat through the evaporation and condensation of the liquid in the fully enclosed vacuum tube. It uses fluid principles such as hair suction to achieve a cooling effect similar to a refrigerator compressor. It has a series of advantages such as extremely high thermal conductivity, good isothermal property, the heat transfer area on both sides of the cold and heat can be changed arbitrarily, heat can be transferred over a long distance, and temperature can be controlled. In addition, the heat exchanger composed of heat pipes has the advantages of high heat transfer efficiency, compact structure, and small fluid resistance loss. Due to its special heat transfer characteristics, the tube wall temperature can be controlled to avoid dew point corrosion.

Liquid cooling is the use of liquid forced to circulate under the drive of a pump to remove heat from the radiator. Compared with air cooling, it has the advantages of quietness, stable cooling, and less dependence on the environment. However, the price of heat pipes and liquid cooling is relatively high, and installation is relatively troublesome.

When choosing a radiator, you can choose according to your actual needs and economic conditions, and the principle is enough.

Ambient heat exchange of heat sink
When the heat is transferred to the top of the radiator, it is necessary to dissipate the transferred heat to the surrounding environment as soon as possible. For air-cooled radiators, it is necessary to exchange heat with the surrounding air. At this time, heat is transferred between two different media. The formula to follow is Q=α X A X ΔT, where ΔT is the temperature difference between the two media, that is, the temperature difference between the radiator and the surrounding air; And α is the thermal conductivity of the fluid, which is a fixed value after the material of the heat sink and the air composition are determined; The most important A is the contact area between the heat sink and the air. Under the premise that other conditions remain the same, such as the volume of the radiator, there is generally a limit, and the space in the case is limited, which will increase the difficulty of installation. By changing the shape of the radiator, increasing its contact area with air, and increasing the heat exchange area, it is an effective means to improve heat dissipation efficiency. To achieve this, the surface area is generally increased by using a fin design supplemented by surface roughening or threads.