Active cooling

With active cooling , the thermal energy is transported away from the component to be cooled with the help of a fan or a pump . In terms of performance, it is far superior to passive cooling .

construction

As a rule, active cooling consists of the following components:

The coolant can consist of air, water or a special coolant , which usually also ensures that the components are lubricated.
A fan or a pump generates a flow of coolant that flows through the heat-transferring radiator and cools the cooling medium down to its starting temperature, or else directly cools the component to be cooled using the air flow.

Performance comparison

The following table shows the structure of the anode and the maximum specific load capacity using the example of transmitter tubes for different types of cooling.

Type of cooling	Anode type	Max. specific load capacity
radiation	Graphite, molybdenum	10 W / cm²
Compressed air	External anode made of Cu with cooling fins	50 W / cm²
Water or oil cooling	External anode made of Cu, surrounded by coolant	100 W / cm²
Evaporative cooling	External anode made of Cu, water is evaporated	500 W / cm²

By far the greatest load capacity results from evaporative cooling. A great deal of energy is used to evaporate the liquid cooling medium in order to be able to deliver a high power density to the coolant (mostly water).

Functional principle of liquid cooling

Main article water cooling

The cooling medium (water, coolant) is conveyed with the help of a pump through various lines to the component to be cooled. There it either flows directly around the component or flows through a special attachment on the component to be cooled (e.g. processor in a PC water cooling system ).

The coolant absorbs the heat from the component and transports it away as it continues to flow. The coolant then flows (with only one component to be cooled) through the radiator , which can be designed either actively with a fan or passively without a fan - but with a larger surface.

The cooling medium can release the heat into the environment through the radiator . A temperature gradient is always necessary for this; the greater the temperature gradient, the greater the amount of heat that can be transferred per unit of time and area.