1 ，heat conduction
The process of heat transfer from the part with higher temperature to the part with lower temperature or to another object with lower temperature in contact with it is called heat conduction. Features: there is no macro displacement between materials, only a heat transfer mode in static materials.
2，Thermal convection (also called convection)
Convective heat transfer refers to the heat transfer process caused by the relative displacement between different parts of the fluid and the mixing of cold and hot fluids due to the macroscopic movement of the fluid. The relative displacement of particles in fluid causes heat exchange. Convective heat transfer only occurs in the fluid, so it is closely related to the flow state of the fluid. In convective heat transfer, there must be heat conduction between fluid particles.
3，Thermal radiation
The transmission process of electromagnetic wave caused by temperature difference in space is called radiative heat transfer, or thermal radiation. As shown in the figure below:
