At the beginning of this year, the sci-fi movie "The Wandering Earth 2" was released, and the popularity remained high. A series of cutting-edge technologies in the film aroused heated discussions among the audience, and the intelligent quantum computer that plays a key role in the plot pushed the plot to a climax.

No matter what kind of electronic products, heating is always a major problem for users. In the movie, the user soaks the computer in a liquid to cool it. This cooling method of "bathing" has caused heated discussions among netizens for a while.

Why should computers "take a bath"? Is it feasible to "bathe" the computer? Let us reveal the secret to you today -

Computers "overheat" to "strike"

As we all know, the chip is the "brain" of the computer, responsible for computing and processing tasks. Like the human brain, the efficiency of a chip is affected by its own state.

As the performance of the chip continues to increase, its power consumption continues to rise, and the power consumption of some commercial server processors can even reach a staggering 700 watts, which is almost equivalent to the power consumption of a 1 horsepower conditioner. Imagine that a small chip works with extremely high power consumption, and in a short period of time, the chip "body temperature" will rise sharply.

The chip "body temperature" mentioned here is actually the shell temperature on the surface of the chip. Generally speaking, the shell temperature on the surface of the chip should be controlled within 85 °C to ensure the normal operation of the chip. If the waste heat generated by the work cannot be dissipated, the "body temperature" of the chip will "cross the safety line" in a short period of time, and a series of abnormal symptoms will appear.

This symptom is somewhat similar to that of a human fever. "Hot heads" can lead to "listlessness" of chips and reduced work efficiency. If the heat is not dissipated in time, the chip temperature will further rise, and it will not take long to "get a high fever". At this time, the power consumption of the chip increases, and the internal components will also be heated and expanded, causing different components to squeeze each other, so that the chip will crack, and may even stimulate high-energy carriers to break down the transistor, seriously reducing the service life of the chip or causing the chip to be scrapped.

In addition, overheating of the chip will also cause the peripheral resistance-capacitor components to be abnormal, resulting in an increase in the supply voltage and supply current of the chip at the same time. If you do not dissipate heat in time at this time and continue to work under heavy load for a long time, a lot of heat will be generated, and the chip may catch fire due to high heat, posing a serious threat to the safety of property and staff.

Therefore, in data centers with a large number of computers working at the same time, there are often one or more sets of efficient and perfect chip cooling solutions to ensure that the chip can work efficiently for a long time at "healthy temperature".

It is urgent for computers to "reduce fever"

At first, due to the low power consumption of computers, the heat generated by the chips inside the computer could be dissipated only by natural convection. Therefore, computer engineers do not need to pay attention to cooling technology.

With the continuous advancement of chip technology, the degree of integration continues to increase, and the power consumption of chips increases sharply, and it is no longer possible to solve the problem of heat dissipation by relying only on natural cooling. As a result, engineers began to introduce forced convection air-cooled heat dissipation technology, which uses highly thermally conductive metal fins to export heat, and then dissipate it through the high-speed rotation of fans - which is why we often hear computers making "humming" sounds.

With its advantages of simple structure and high reliability, air-cooled technology has occupied the mainstream of the market for a long time. However, when the power consumption of the chip becomes high, even reaching 300 watts, the use of air cooling technology will make the volume of the radiator and fan larger, and the noise caused by the high-speed rotation of the fan will be unbearable.

To this end, engineers have proposed a second path: liquid cooling technology.

Liquid cooling technology, with its high specific heat capacity, can take away more heat than air cooling technology through direct or indirect contact with the heat source. At present, the supercomputer Frontier of the United States, China's supercomputer Sunway Taihu Light, and Japan's supercomputer Fugaku all use cold plate liquid cooling technology with water as the cooling medium. In many aspects such as system performance, chip power, assembly density, and operating noise, the application of liquid cooling technology has brought great improvements to data centers and supercomputing.

Of course, cold plate liquid cooling technology also has its disadvantages: on the one hand, water is used as the cooling medium, once leakage, it will damage electronic components; On the other hand, if you want to achieve heat dissipation of all components inside the computer, the cold plate structure will become extremely complex and extremely difficult to design.

Driven by market demand, an immersion liquid cooling technology began to emerge. This technology dissipates heat from all components by immersing the entire motherboard directly in coolant with good cooling performance and insulating characteristics. In December 2022, Iceotope, a global leader in precision immersion liquid cooling, announced a new study in collaboration with Meta. Research confirms the efficiency, practicality, and effectiveness of rack-scale liquid cooling technology to meet the cooling requirements of high-density storage disks that are widely deployed and used in hyperscale data centers. The study also successfully demonstrated that precision immersion cooling is more effective than conventional cold plate liquid cooling.

It is understood that liquid cooling technology is becoming a new technology direction for the development of global data centers. IBM, Google, Intel and other international giants have launched a layout in this field. IBM released a related liquid-cooled supercomputer, which can reduce energy consumption by more than 40% and reduce carbon emissions by 85%; Google adopts liquid cooling technology in its data centers and continues to promote the transformation of data center cooling methods to liquid cooling; Alibaba Zhejiang Cloud Computing Renhe Data Center, the world's largest immersion liquid-cooled data center, has been put into use immersion liquid cooling technology in 2020, which can save more than 70% energy for data centers.

The future of liquid cooling technology is promising

Nowadays, cooling technology has become a hot area of scientific and technological competition in various countries: some engineers have developed jet impact liquid cooling technology, which can achieve about 1 watts of heat dissipation on a chip of 1100 square centimeter; In 2019, Nature magazine announced a microfluidic channel cooling technology integrated inside the chip, which can achieve about 1 watts of heat dissipation on a 1700 square centimeter chip, or will become an effective technical means to achieve ultra-high power chip cooling in the future; There are also engineers who propose boiling immersion liquid cooling technology, which has almost no additional electrical energy input in the entire heat dissipation process, and is expected to achieve "zero energy consumption" cooling...

Sun Ninghui, an academician of the Chinese Academy of Engineering, once said: "When a country's computing power index reaches more than 40 points, every 1 point increase in the index will increase the pull of GDP growth to 1.5 times." "The advancement of liquid cooling technology has promoted the stable output of computing power and efficient improvement of computing performance of server equipment, which in turn has had a positive impact on many fields.

In the military field, liquid cooling technology is also playing an increasing role.

On the battlefield, liquid cooling technology is applied to the command post computer system, which can greatly improve the degree of system integration. Especially in the field or tunnels, liquid cooling technology makes the command post computer have stronger performance, longer endurance and better concealment, so as to better ensure command decisions.

In terms of equipment, laser weapons use liquid cooling technology, which can improve the laser output power density and beam quality, increase the lethal performance of laser weapons and have a smaller volume, which is conducive to improving the rapid deployment capability of weapon systems; Active phased array radar adopts liquid cooling technology, which can greatly improve the radar power, so that the radar detection distance is longer, and the detection accuracy and reliability are higher.

Powerful fire systems are also inseparable from liquid cooling technology. To ensure a stable output of the fire system for a long time, many weapons and equipment are directly equipped with liquid cooling systems. For example, the famous Maxim heavy machine gun uses liquid cooling technology to ensure the high-speed and stable output of bullets.

In addition, liquid cooling technology has entered people's daily lives. Some technology companies apply liquid cooling technology to customized personal computers, which greatly improves the performance of computers and enables users to have a better experience. A domestic electric vehicle company applied liquid cooling technology to electric vehicle motors, and the unique liquid cooling method not only solved the industry's "old and difficult" demagnetization endurance, but also solved the problems of motor rust and easy demagnetization in one stop, which is a subversive innovation for the electric vehicle industry. In the field of superconductivity, superconducting cables can be immersed in extremely low temperature liquids such as liquid helium to achieve zero-loss power transmission, and related technologies are expected to be applied to high-voltage power transmission.

All in all, liquid cooling technology is one of the indispensable and important technologies for computer systems after the performance of chips is improved. In the environment where governments pay more and more attention to data center energy consumption indicators, more air-cooled data centers will be eliminated in the future, and liquid cooling technology is gradually replacing the former as the mainstream technology at home and abroad. In the future, it is possible to achieve full liquid cooling and heat dissipation from supercomputer systems to small personal computers. In a future where humans and information devices become more and more connected, liquid cooling technology will provide more and more quality services for our lives.

Lu Xinyi Deng Zeng, Gao Lihua