What are the advantages of liquid-cooled servers over ordinary servers?

As we all know, if the heat dissipation is poor, the high temperature will not only reduce the stability of the chip's work, but also because of the temperature difference between the module's internal and external environments and generate excessive thermal stress, affecting the chip's electrical properties, operating frequency, mechanical strength and reliability.

With the development of data centre to high density and high power, the traditional air-cooling technology can not fully meet its cooling needs. Liquid cooling technology can significantly reduce the energy consumption of data centres.

Liquid cooling technology has the following obvious advantages over traditional air-cooling technology: 

- More heat removal: the same volume of liquid removes nearly 3,000 times more heat than the same volume of air.

- Faster temperature transfer: Liquid has 25 times the thermal conductivity of air.

- Better noise quality: at the same level of heat dissipation, the noise level of liquid cooling is 20-35 dB lower than that of air cooling.

- More energy saving: Liquid cooling system saves about 30%-50% of electricity compared to air-cooled system.

Immersion:

Submerge the heating element directly in the coolant, relying on the flow of liquid circulation to take away the heat generated by the operation of servers and other equipment. Submerged liquid cooling is a typical direct contact liquid cooling. Due to the direct contact between the heating element and the cooling liquid, the heat dissipation efficiency is higher, the noise is lower, and the anti-high-heat riddle can be solved. Submerged liquid cooling is divided into two-phase liquid cooling and single-phase liquid cooling, heat dissipation can be used in the form of dry cooler and cooling tower.

- Two phase liquid cooling

The phase change of the coolant occurs in the circulation of heat dissipation. Two phase liquid cooling heat transfer efficiency is higher, but the control is relatively complex. The pressure will change in the process of phase change, high requirements for the container, the use of the coolant is easy to be contaminated.

- Single-phase liquid cooling

The coolant always maintains the liquid state in the heat dissipation process, and no phase change occurs, so the boiling point of the coolant is required to be higher, so that the control of coolant evaporation and loss is relatively simple, and the compatibility with the components of the IT equipment is better, but compared with the two-phase liquid cooling, its efficiency is lower. According to the actual application scenario, dry cooler or cooling tower can be used to dissipate heat.

Coolant type:

Water

Liquid cooling is the most direct and least expensive. Water is not an insulator and can only be applied to indirect contact type liquid cooling. In case of leakage, the damage to IT equipment such as servers will be very fatal.

Mineral Oil

Mineral oil is also an inexpensive coolant. Single-phase mineral oil is non-toxic, odourless and non-volatile. It is highly viscous and tends to form a residue on equipment surfaces. Although it has a high ignition point, it has the potential to burn under certain specific conditions.

Fluorinated fluids

The best feature is that it is insulating and non-flammable. It is the safest of the liquid cooling technologies in data centres. Currently the most widely used. But the price is high.