In response to the high-density heat dissipation demands, liquid cooling technology has developed multiple approaches, mainly including cold plate liquid cooling, immersion liquid cooling, and spray liquid cooling. Among these, cold plate liquid cooling is currently the mainstream mature technology solution, which can be divided into single-phase cold plate liquid cooling and two-phase cold plate liquid cooling.
Architecture and Compatibility of Liquid Cooling Systems
Compared to immersion liquid cooling, cold plate liquid cooling has better compatibility with traditional server architectures and does not significantly change the overall weight, which means it does not impose high requirements on the load-bearing capacity of data centers. It is suitable for upgrading and renovating existing data centers and is more conducive to later upgrading from single-phase cold plates to two-phase cold plates.
Additionally, cold plate liquid cooling has lower modification requirements for CPUs/GPUs, with minimal changes needed for the supporting electrical racks. The cooling liquid does not come into direct contact with electrical components, which can help avoid many compatibility issues. Furthermore, under the same heat dissipation conditions, the pump drive energy consumption of two-phase cold plate liquid cooling systems is lower compared to that of single-phase cold plates and immersion liquid cooling circulation systems.
Cost-effectiveness
In the low-pressure phase change cooling liquid circulation process, aluminum can replace copper to avoid the use of high-cost metals like stainless steel and copper in the piping, thereby reducing the system piping costs. Compared to immersion liquid cooling, which uses large amounts of electronic fluorinated liquids or mineral oils, the quantity of cooling liquid used in cold plate liquid cooling systems and the losses during regular maintenance are much lower than those in immersion liquid cooling, resulting in reduced initial investment.
Cooling Liquid Properties
Electronic fluorinated liquids/refrigerants have very low electrical conductivity and are commonly used for cleaning electrical components. Even in the event of a leak, they do not cause damage to electrical components. Electronic fluorinated liquids/refrigerants are pure substances, so there is no need to add inhibitors or biocides during the system circulation, ensuring the cleanliness of the system and reducing the risk of corrosion. Thanks to the mature technology of traditional refrigeration systems, the system can maintain cleanliness for an extended period after installing a drying filter, significantly reducing the probability of clogging and corrosion in the piping.
The boiling heat transfer efficiency generated during the phase change of the cooling liquid is approximately 3 to 10 times that of single-phase convective heat transfer efficiency, which can meet high-density heat dissipation demands. Additionally, the heat capacity of the phase change cooling liquid is higher than the sensible heat of single-phase cooling liquids, allowing the system to meet heat dissipation requirements at low flow rates, thereby reducing the power consumption of the circulation pump.
This cooling method utilises the process of evaporating a liquid fluid (typically a refrigerant) into a vapor to remove heat from electronic components. The process involves pumping a refrigerant into a heat exchanger or cold plate that is located directly on the chip. Because there is phase change to the fluid, it is more efficient than keeping the fluid in a same state. This is called latent heat exchange.
Although two-phase cold plate liquid cooling systems have a series of advantages, most domestic suppliers are still in the research and development stage, with few mass production projects, and they still face some technical challenges:
Even though two-phase cold plate liquid cooling technology still has a long way to go, it will eventually secure a place in the liquid cooling market as the demand for high-density heat dissipation increases or as the need for low-version chips to perform overclocking operations under low-temperature conditions rises.
As a pioneer in the field of motion and control, Parker Hannifin is actively pursuing cutting-edge technology exploration in data center cooling systems. The company is collaborating with several international server and thermal management system suppliers to explore two-phase cold plate liquid cooling technology, aiming to work together with customers for mutual benefit and to safeguard the future computing power market for information technology, intelligence, and commercialization!