With the advent of the 5G Internet of Everything era, the demand for high-performance and high-density computing has accelerated, and the problem of data center energy consumption has become increasingly prominent.

How much do you know about liquid-cooled heat dissipation? Which liquid cooling method should I choose? What should I choose for the freezing liquid?

1 The trend of liquid cooling technology has become established

As we all know, if the heat dissipation is poor, the high temperature will not only reduce the stability of the chip, but also because of the temperature difference between the internal and external environment of the module

Thermal stress affects the electrical performance, operating frequency, mechanical strength and reliability of the chip. The failure rate of electronic components increases exponentially with the increase in operating temperature, and the reliability of the system will be reduced by 50% for every 10 degrees increase in the temperature of a single semiconductor component.

Dealing with the "power wall" of big data and ultra-dense computing, and using liquid coolant instead of air to cool computer equipment, is a technological revolution in the future data center. /b14> According to ResearchAndMarkets, the global liquid-cooled data center market size will reach $4.55 billion by 2023, with a compound annual growth rate of 27.7%. 

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

- Heat takes away more: Liquids of the same volume take away nearly 3,000 times more heat than the same volume of air.

- Faster temperature transfer: Liquids conduct heat 25 times more than air.

- Better noise quality: The level of liquid cooling noise is 20-35 decibels lower than that of air cooling noise.

- Power consumption and energy saving: the liquid cooling system saves about 30%-50% more electricity than the air cooling system.

2 classification of liquid cooling

The so-called liquid cooling does not simply refer to water. It refers to the use of a liquid with a high specific heat capacity as a transmission medium to take away the heat generated by IT equipment or servers and cool it. At present, there are three main deployment methods of liquid cooling technology, namely immersion, cold plate and spraying.

Cold plate type:

The liquid cold plate is fixed to the main heating device of the server, and the liquid flowing through the cold plate is relied on to take the heat away to achieve the purpose of heat dissipation. Cold plate liquid cooling solves the heat dissipation of devices with large heat generation in the server, and other heat dissipation devices have to rely on air cooling. Therefore, the server using cold plate liquid cooling is also called a gas-liquid dual-channel server. The liquid of the cold plate does not contact the cooled device, and the heat transfer plate is used in the middle, which is highly safe.

Spray type:

In the reservoir top reservoir and open hole, according to the position of the heating element and the size of the heat generation, let the coolant spray the heating body to achieve the purpose of cooling the equipment. The sprayed liquid is in direct contact with the cooled device, and the cooling efficiency is high; however, the liquid will encounter high-temperature objects during the spraying process, and the fog droplets and gas will be emitted to the outside of the chassis along the holes and gaps in the chassis, causing the cleanliness of the machine room environment to decrease or affect other equipment.

Immersion:

The heating element is directly submerged in the coolant, relying on the flow cycle of the liquid to take away the heat generated by the operation of equipment such as servers. Immersion liquid cooling is typical of direct contact liquid cooling. Due to the direct contact between the heating element and the coolant, the heat dissipation efficiency is higher and the noise is lower, which can solve the mystery of high heat resistance. Immersion liquid cooling is divided into two-phase liquid cooling and single-phase liquid cooling, and the heat dissipation method can be in the form of dry cooler and cooling tower.

- Two-phase liquid cooling

The coolant undergoes a phase change in circulating heat dissipation. Two-phase liquid-cooled heat transfer is more efficient, but the control is relatively complex. Pressure changes during phase change, placing high demands on the vessel and making the coolant susceptible to contamination during use.

- Single-phase liquid cooling

The coolant always maintains the liquid state during the circulating heat dissipation process, and no phase change occurs, so the boiling point of the coolant is required to be higher, so that the coolant volatilization loss control is relatively simple, and the components of the IT equipment are more compatible, but compared with the two-phase liquid cooling, its efficiency is lower. Depending on the actual application scenario, a dry cooler or cooling tower can be used to dissipate heat.

3 Coolant

water

Liquid cooling is the most direct and the lowest cost. Water is not an insulator and can only be applied to indirect contact liquid cooling. Once a leak occurs, damage to IT equipment such as servers can be very fatal.

mineral oil

Mineral oil is also an inexpensive coolant. Single-phase mineral oil is non-toxic, tasteless and not volatile. The viscosity is high and it is easy to form residues on the surface of the equipment. Although the ignition point is high, it is still possible to burn under certain conditions.

Fluorinated solution

The biggest feature is insulation and non-combustible. It is the most secure of liquid cooling technologies in data centers. At present, it is the most widely used. But the price is high.

Liquid cooling technology is mainly used in the field of high-performance computing. With the development of data centers to high density and high power, traditional air cooling technology can no longer fully meet its heat dissipation needs. These are the main factors contributing to the sinking of liquid-cooled technology. Liquid cooling technology can significantly reduce energy consumption in data centers. For example, the PUE of many immersive liquid-cooled data centers can even reach a staggering 1.03-1.05. However, the same size of the air-cooled system data center, its PUE value is still between 1.3-1.5.

In addition to the traditional large-scale data centers, with the advent of the edge computing era, about 20% of edge data centers will also use liquid cooling technology. Data centers that apply liquid cooling systems can recover their investment in refrigeration systems within two to three years of completion, and the electricity costs saved later can be seen as their benefits. And the larger the data center, the better it works.

4 Rack-mounted liquid cooling solutions

Rackmount GPU liquid cooled servers can accommodate as many GPU graphics cards as possible in tight spaces. By customizing the Blue Ocean Brain's high-quality liquid cooling system, graphics cards and processors can achieve higher boost clock rates. The density of hardware packaging for each server rack is maximized, bringing up the best performance of the hardware even under continuous loads without worrying about any thermal issues. Widely used in 3D rendering, visual deep learning, AI computing, 3D CAD, scientific computing (astronomy, geology, weather, etc.) and so on. Blue Ocean Brain has provided liquid cooling solutions for a number of customers, helping customers achieve efficient heat dissipation, energy saving and consumption reduction, rapid deployment, etc.

Product form

- The compact cooling solution is perfectly adapted to the user's needs, with clever design and reliable performance

- Rackmount design, plug and play. Quick and easy to put into use

- All components maintain the maximum possible cycle without throttling due to high temperatures

- Supports up to 9 GPU graphics cards and 2 CPU processors

- Continuous and quiet thermal transition with minimal downtime

- Meets the requirements of supercomputers. All graphics cards run 100% permanently and will not shorten the runout cycle due to overheating. Significantly reduce volume and heat generation.

- The rack's storage space can be greatly expanded and can be used for cloud storage services

- Compared with air cooling, liquid cooling systems are denser, more energy-efficient, and have better anti-noise effect