The challenge of liquid cooling for data center cooling is changing. High-performance computing (HPC), artificial intelligence applications, and cryptocurrency mining generate more heat than traditional computer servers and need advanced solutions to manage the heat load effectively and efficiently. 
Traditional liquid cooling for data center design includes the use of cold air to dissipate heat. The server rack and room air handler (CRAH) units are positioned to form the "hot aisle" and "cold aisle". By using an elevated floor air supply room, the CRAH unit provides cold air for the cold aisle. The fan blows air through the server, transfers heat from the server to the air, and then discharges the hot air into the hot aisle.
This method has been successfully implemented for decades, even though the thermal density has been increasing. But now, with the exponential growth of generative artificial intelligence, high-performance computing, and other ultra-intensive computing applications, the industry has reached a critical threshold.
Just a few years ago, the average heat output of a typical server rack was between 5 and 10 kilowatts, and in some extreme cases, it was as high as 12 kilowatts. However, with the arrival of a new application wave, the thermal density of each rack has soared to 50-100 kilowatts. The "tried and tested" cooling technology in the past simply cannot withstand these extreme loads. It is generally believed that liquid cooling is the gold standard in the future.
Liquid cooling can take several forms, including but not limited to back door heat exchanger, immersion cooling, and direct-to-chip cooling (sometimes called cold plate cooling). Each application has its unique flow control challenges.
Showed great interest in the field of liquid cooling for data centers and developed innovative solutions to simplify and optimize the transition to liquid cooling and support its continuous operation. By integrating measurement technology and advanced computing power into standard mechanical valves, takes the lead in developing smarter valves, providing functions far beyond basic position control.
Traditionally, control valves have relied on position control technology, which relates control signals to the opening geometry of the valve. This basic technology determines how much cross-sectional area is exposed to allow fluid to pass through the valve. Similar to controlling airflow by adjusting the opening of windows, this method can be challenging. Because the flow rate depends not only on the exposed cross-sectional area but also on the pressure difference, it is difficult to control it accurately.
Flow control is a more advanced technology, which refers to the behavior of valves independent of pressure. Different from the traditional methods of controlling valve opening and relying on appropriate pressure to achieve the required flow, the flow control valve directly adjusts the flow, usually regardless of pressure and valve position. Electronic pressure-independent (PI) valves are especially suitable for liquid cooling in the data centers industry. More details about the electronic PI valve solution for liquid cooling applications will be discussed in an upcoming blog post.
Power control is based on flow control by measuring the flow and temperature difference (Δ t) through the heat transfer device. Using these data, the valve can interpret the control signal from the building automation system (BAS) as the power demand. According to the measured δ T of water, it can adjust the flow rate to exchange a specified amount of heat energy, whether expressed in BTUh, ton, KW, or other units.
Differential pressure control is a completely different method. According to physics, the flow rate (Cv) is directly proportional to the flow rate, rising and falling at the same time. By maintaining a fixed pressure difference (DP) in the loop, the valve can adjust the flow to match the change in flow requirements. When the components are taken out of the circuit, for example, when the server is taken out of the rack for maintenance, the valve will reduce the flow accordingly to maintain a fixed DP.