Talking about the thermal design in LED light source products

1.1 Heat conduction

When there is a temperature difference in the static medium, whether the medium is solid or liquid, heat transfer occurs in the medium. This process is heat conduction, and heat conduction is the transfer of energy due to the temperature difference.

1.2 Convection

When a surface and a moving fluid are at different temperatures, the heat transfer between them is convective.

1.3 Thermal radiation

On all variable surfaces with temperature, energy is emitted in the form of electromagnetic waves. This process is called thermal radiation.

1.4 Heat flux density

The heat flux density is a vector with directionality equal to the amount of heat flowing per unit time over the vertical unit area in that direction, in units of W/m2.

1.5 convective heat transfer coefficient

It represents the heat exchange capacity per unit time unit heat exchange area under the unit temperature difference, and thus can be used to measure the difference in heat transfer performance of various convective heat transfer processes. The unit is W/m2.K.

The following is a convective heat transfer coefficient comparison reference table

1.6 Thermal conductivity (thermal conductivity)

The thermal conductivity refers to the heat of 1m thick material under stable heat transfer conditions. The temperature difference between the two sides is 1 degree. In 1 hour, the heat transferred through the area of ​​1 square meter is in W/mk. The thermal conductivity is The physical properties inherent in the material of the object are related to the composition, structure, density, pressure and temperature of the material.

1.7 Thermal resistance

Thermal resistance is the ability of a material per unit area and unit thickness to block heat flow in units of W/°C. For a single homogeneous material, the thermal resistance of the material is proportional to the thickness of the material; for non-single materials, the general trend is that the thermal resistance of the material increases as the thickness of the material increases.

1.8 thermal impedance

Thermal impedance is defined as the product of the thermal resistance between the heat transfer area and the contact surface in W/°C.m2.

2. Common heat dissipation methods and corresponding theoretical calculation methods

2.1 Thermal conductivity (heat conduction) theoretical calculation method

Fourier heat conduction law:

A is the cross-sectional area perpendicular to the direction of heat flow; λ is the thermal conductivity of the material, in units of W/(m?K), which is a physical property parameter that characterizes the thermal conductivity of the material.