The fundamental effect of heat transfer is that the particles of one substance flow with the particles of another substance. The most energetic substance usually loses internal energy (i.e. cold) while the least energetic substance gains internal energy (i.e. heat).

Friction causes. Friction is a force that resists the relative movement between two objects or materials. The causes of this resistive force are molecular adhesion, surface roughness and deformations. Adherence is the molecular force resulting from the entry in close contact between two materials.

1. Conventional heat transfer coefficient on the side of the cold fluid (which in turn depends on the flow, turbulent, fluid viscositis, surface geometry, etc.) 2. Conventional heat transfer coefficient on the side of the heat fluid (which in turn depends on the flow, turbulent, fluid viscositis, surface geometry, etc.)

Factors affecting the heat flow rate include material conductivity, temperature difference between material, material thickness and material surface. Different materials have a higher or lower resistance to heat transfer, making them better insulation or better conductors.

The increase in temperature increases the reaction rates due to the disproportionate increase in the number of high-energy collisions. Only these collisions (at least the reaction activation energy) cause a reaction.