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Heat convection!? That's how it turns out

In the natural heat exchange process, heat will be transferred from high temperature to low temperature. This phenomenon is called heat transfer. The heat transfer methods include heat conduction, heat convection, and heat radiation. Among them, thermal convection refers to the movement of molecules inside the fluid, which often occurs in the fluid or when there is a temperature difference between the fluid and the solid.

Because the difference in temperature will cause the density of the fluid to be different, when the liquid or gaseous substance is heated, the volume expands to reduce the density, and the substance gradually rises. The original position is supplemented by the low temperature and high density substance, and the substance rises again when heated. , The surrounding material is replenished again, so that the circulation spreads the heat from the fluid to everywhere, which is heat convection.

 

In heat transfer, convection is divided into natural convection and forced convection. Natural convection refers to the phenomenon that occurs when there is a temperature difference between fluids. For example, hot air rises and cold air falls (because the density of hot air is lower than that of cold air, it will rise, while the density of cold air is higher than that of hot air, so it will drop) . Forced convection refers to the convection phenomenon caused by the fluid being pushed by an external force (such as a pump or fan). For example: electric fan heater, when the wind blows over the heating element, the air is heated. Or when a person blows at the food, because the temperature of the gas is lower, the temperature of the food is lowered, and forced convection is used.

 

Local heat flux can be written as

 

Among them, h is the thermal convection coefficient, the higher the h, the better the thermal convection effect.

The factors that affect the thermal convection coefficient include: fluid motion state (flow rate and direction), fluid type and its physical properties, shape and surface state of heat transfer solids, etc.

For heat dissipation fins, fins with a closer fin spacing have better heat dissipation effects, but if the fin spacing is too small, so that air cannot enter the fins for heat exchange, the heat dissipation effect will be reduced.

The best fin spacing can be found through thermal simulation.

Generally speaking, heat sources below 10W use natural convection, which can be solved by increasing air convection through heat dissipation fins and matching the openings of the housing, while heat sources above 10W need to use forced convection to dissipate heat.

 

 

Editorial staff T-Global Marketing


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T-Global R&D team

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A team of professional heat flow engineers, with independent and innovative research and development, provides customers with preliminary thermal simulation planning and institutional heat dissipation design consulting. In the face of evolving market trends, they can quickly respond and continue to provide innovative anti-heat solutions.

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