Ann: VHD Technology - Thermal Performance Breakthrough, page-65

Diffusivity is a difficult concept to get one’s head around

one way of thinking about it is:

imagine a heat sink you need to quickly take away excess heat energy generated by CPU.
The heat sink acts like a pipe between the CPU (hot face) and cooling fins to maximise offloading excess heat energy to the environment quickly (cold face).

The tricky bit is that

1) The CPU only has a very small surface available from where the heat can be extracted, so the heat sink must be able to move a large amount of heat energy though a small ‘pipe’ from the hot CPU surface to the cooling fins. The larger the heat flow capacity of the sink material,the better.

2) The heat sink itself needs to stay cool while transferring the heat energy to the cooling fins, so the smaller the heatstored by the heat sink material, the better.

The ratio of heat transfer capacity and heat storage capacity looks like this:

Heat energy flowing through the material , passing from
source to environment

----------------------------------------------------------------

Heat stored by the material through which
the heat energy is conducted

That ratio is the thermal diffusivity

The value of thermal diffusivity is a characteristic of the heat sink material. it is the ratio of the capacity to transfer heat through the material( thermalconductivity) and of the volumetric capacity to store heat, (specific heatcapacity x density) .

The higher the thermal diffusivity the better
DYOR
Hoping for a better day tomorrow